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Cellular metabolism can be envisaged by fluorescence lifetime imaging of fluorophores sensitive to specific intracellular factors such as [H+], [Ca2+], [O2], membrane potential, temperature, polarity of the probe environment, and alterations in the conformation and interactions of macromolecules. Lifetime measurements of the probes allow the quantitative determination of the intracellular factors. Fluorescence microscopy taking advantage of time-correlated single photon counting is a novel method that outperforms all other techniques with its single photon sensitivity and picoseconds time resolution. In this work, a time- and space-correlated single photon counting system was established to investigate the behavior of 2-(4-(dimethylamino)styryl)-1-methylpyridinium iodide (DASPMI) in living cells. DASPMI is known to selectively stain mitochondria in living cells. The uptake and fluorescence intensity of DASPMI in mitochondria is a dynamic measure of membrane potential. Hence, an endeavour was made to elucidate the mechanism of DASPMI fluorescence by obtaining spectrally-resolved fluorescence decays in different solvents. A bi-exponential decay model was sufficient to globally describe the wavelength dependent fluorescence in ethanol and chloroform. While in glycerol, a three-exponential decay model was necessary for global analysis. In the polar low-viscous solvent water, a mono-exponential decay model fitted the decay data. The sensitivity of DASPMI fluorescence to solvent viscosity was analysed using various proportions of glycerol/ethanol mixtures. The lifetimes were found to increase with increasing solvent viscosity. The negative amplitudes of the short lifetime component found in chloroform and glycerol at the longer wavelengths validated the formation of new excited state species from the initially excited state. Time-resolved emission spectra in chloroform and glycerol showed a biphasic increase of spectral width and emission maxima. The spectral width had an initial fast increase within 150 ps and a near constant thereafter. A two-state model based on solvation of the initially excited state and further formation of TICT state has been proposed to explain the excited state kinetics and has been substantiated by the de-composition of time-resolved spectra. The knowledge of DASPMI photophysics in a variety of solvents now provides the means of deducing complex physiological parameters of mitochondria from its behavior in living cells. Spatially-resolved fluorescence decays from single mitochondria or only very few organelles of XTH2 cells signified distinctive three-exponential decay kinetics of viscous environment. Based on DASPMI photophysics in a variety of solvents, these lifetimes have been attributed to the fluorescence from locally excited state (LE), intramolecular charge transfer state (ICT) and twisted intramolecular charge transfer (TICT) state. A considerable variation in lifetime among mitochondria of different morphology and within single cell was evident corresponding to the high physiological variations within single cells. Considerable shortening of the short lifetime component (τ1) under high membrane potential condition, such as in the presence of ATP and/or substrate, was similar to quenching and dramatic decrease of lifetime in polar solvents. Under these conditions τ2 and τ3 increased with decreasing contribution. Upon treatment with ionophore nigericin, hyperpolarization of mitochondria resulted in remarkable shortening of τ1 from 159 ps to 38 ps. Inhibiting respiration by cyanide resulted in notable increase of mean lifetime and decrease of mitochondrial fluorescence. Increase of DASPMI fluorescence on conditions elevating mitochondrial membrane potential has been attributed to uptake according Nernst distributions, to de-localisation of π electrons, quenching processes of the methyl pyridinium moiety and restricted torsional dynamics at the mitochondrial inner membrane. Accordingly, determination of anisotropy in DASPMI stained mitochondria in living XTH2 cells, revealed dependence of anisotropy on membrane potential. Such changes in anisotropy attributed to restriction of the torsional dynamics about the flexible single bonds neighboring the olefinic double bond revealed the previously known sub-mitochondrial zones with higher membrane potential along its length. Membrane-potential-dependent changes in anisotropy have further been demonstrated in senescent chick embryo fibroblasts. In conclusion, spectroscopic observations of excited-state kinetics of DASPMI in solvents and its behavior in living cells had revealed for the first time its localisation, mechanism of voltage sensitive fluorescence and its membrane-potential-dependent anisotropy in living cells. The simultaneous dependence of DASPMI photophysics on mitochondrial inner membrane viscosity and transmembrane potential has been highlighted.
Maize and rice constitute some of the most important cereals cultivated in the world, being used as staple food for people especially in Africa. The rice moth, Corcyra cephalonica, and the maize weevil, Sitophilus zeamais, are major pests of stored grains in the tropics. The use of parasitoids in biological pest control is already common in different agricultural and horticultural fields. At present, grain managers tend to look at alternatives to chemicals to control insects in stored grain. Lariophagus distinguendus (Förster) is a synovigenic, solitary larval and pupal ectoparasitoid of several beetle species that infest stored goods. The ability for long-range host finding of this parasitoid mediated by volatiles has been shown (Steidle & Schöller 1997). Habrobracon hebetor (Say) is a gregarious ectoparasitoid of many lepidopterous pests. This wasp occurs naturally in the stored grain ecosystem (Keever & al. 1985) where it attacks several pyralid moths, including the rice moth, Corcyra cephalonica. The present study was conducted to assess the host finding of the two parasitoids H. hebetor and L. distinguendus.
Jüdische Grabsteinepigraphik: R. Yosef Trani (1568-1639), R. Akiva Eger (d. 1837), R. David Hoffmann (d. 1921)
The enigmatic R. David Lida
(2008)
Chemical ozone loss in winter 1991–1992 is recalculated based on observations of the HALOE satellite instrument, Version 19, ER-2 aircraft measurements and balloon data. HALOE satellite observations are shown to be reliable in the lower stratosphere below 400 K, at altitudes where the measurements are most likely disturbed by the enhanced sulfate aerosol loading, as a result of the Mt.~Pinatubo eruption in June 1991. Significant chemical ozone loss (13–17 DU) is observed below 380 K from Kiruna balloon observations and HALOE satellite data between December 1991 and March 1992. For the two winters after the Mt. Pinatubo eruption, HALOE satellite observations show a stronger extent of chemical ozone loss towards lower altitudes compared to other Arctic winters between 1991 and 2003. In spite of already occurring deactivation of chlorine in March 1992, MIPAS-B and LPMA balloon observations indicate that chlorine was still activated at lower altitudes, consistent with observed chemical ozone loss occurring between February and March and April. Large chemical ozone loss of more than 70 DU in the Arctic winter 1991–1992 as calculated in earlier studies is corroborated here.
During the APE-THESEO mission in the Indian Ocean the Myasishchev Design Bureau stratospheric research aircraft M55 Geophysica performed a flight over and within the inner core region of tropical cyclone Davina. Measurements of total water, water vapour, temperature, aerosol backscattering, ozone and tracers were made and are discussed here in comparison with the averages of those quantities acquired during the campaign time frame. Temperature anomalies in the tropical tropopause layer (TTL), warmer than average in the lower part and colder than average in the upper TTL were observed. Ozone was strongly reduced compared to its average value, and thick cirrus decks were present up to the cold point, sometimes topped by a layer of very dry air. Evidence for meridional transport of trace gases in the stratosphere above the cyclone was observed and perturbed water distribution in the TTL was documented. The paper discuss possible processes of dehydration induced by the cirrus forming above the cyclone, and change in the chemical tracer and water distribution in the lower stratosphere 400–430 K due to meridional transport from the mid-latitudes and link with Davina. Moreover it compares the data prior and after the cyclone passage to discuss its actual impact on the atmospheric chemistry and thermodynamics.
Appropriate precautions in the case of flood occurrence often require long lead times (several days) in hydrological forecasting. This in turn implies large uncertainties that are mainly inherited from the meteorological precipitation forecast. Here we present a case study of the extreme flood event of August 2005 in the Swiss part of the Rhine catchment (total area 34 550 km2). This event caused tremendous damage and was associated with precipitation amounts and flood peaks with return periods beyond 10 to 100 years. To deal with the underlying intrinsic predictability limitations, a probabilistic forecasting system is tested, which is based on a hydrological-meteorological ensemble prediction system. The meteorological component of the system is the operational limited-area COSMO-LEPS that downscales the ECMWF ensemble prediction system to a horizontal resolution of 10 km, while the hydrological component is based on the semi-distributed hydrological model PREVAH with a spatial resolution of 500 m. We document the setup of the coupled system and assess its performance for the flood event under consideration. We show that the probabilistic meteorological-hydrological ensemble prediction chain is quite effective and provides additional guidance for extreme event forecasting, in comparison to a purely deterministic forecasting system. For the case studied, it is also shown that most of the benefits of the probabilistic approach may be realized with a comparatively small ensemble size of 10 members.
The main objective of the study presented in this paper was to develop an evaluation scheme which is suitable for spatially explicit groundwater vulnerability assessment according to the Water Framework Directive (WFD). Study area was the Hase river catchment, an area of about 3 000 km2 in north-west Germany which is dominated by livestock farming, in particular pig and poultry production. For the Hase river catchment, the first inventory of the WFD led to the conclusion that 98% of the catchment area is "unclear/unlikely" to reach a good groundwater status due to diffuse nitrogen emissions from agriculture. The groundwater vulnerability assessment was embedded in the PartizipA project ("Participative modelling, Actor and Ecosystem Analysis in Regions with Intensive Agriculture", www.partizipa.net), within which a so-called actors´ platform was established in the study area. The objective of the participatory process was to investigate the effects of the WFD on agriculture as well as to discuss groundwater protection measures which are suitable for an integration in the programme of measures. The study was conducted according to the vulnerability assessment concept of the Intergovernmental Panel on Climate Change, considering sensitivity, exposure and adaptive capacity. Sensitivity was computed using the DRASTIC index of natural groundwater pollution potential. Exposure (for a reference scenario) was computed using the STOFFBILANZ nutrient model. Several regional studies were analysed to evaluate the adaptive capacity. From these studies it was concluded that the adaptive capacity in the Hase river catchment is very low due to the economic importance of the agricultural sector which will be significantly affected by groundwater protection measures. As a consequence, the adaptive capacity was not considered any more in the vulnerability assessment. A groundwater vulnerability evaluation scheme is presented which enjoys the advantage that both exposure and sensitivity can be operationalized in a spatially resolved manner (500×500 m grid) by the two models mentioned above. The evaluation scheme was applied in the Hase river catchment. 21% of the catchment was classified as highly vulnerable, another 73% as medium vulnerable. Only 6% of the Hase river catchment has low vulnerability. Grid cells of the high vulnerability class are considered as priority areas for groundwater protection measures in the programme of measures of the WFD. Measures will be particularly effective in the north-eastern part of the catchment where groundwater vulnerability is mainly due to high nitrogen emissions.
Strong perturbations of the Arctic stratosphere during the winter 2002/2003 by planetary waves led to enhanced stretching and folding of the vortex. On two occasions the vortex in the lower stratosphere split into two secondary vortices that re-merged after some days. As a result of these strong disturbances the role of transport in and out of the vortex was stronger than usual. An advection and mixing simulation with the Chemical Lagrangian Model of the Stratosphere (CLaMS) utilising a suite of inert tracers tagging the original position of the air masses has been carried out. The results show a variety of synoptic and small scale features in the vicinity of the vortex boundary, especially long filaments peeling off the vortex edge and being slowly mixed into the mid latitude environment. The vortex folding events, followed by re-merging of different parts of the vortex led to strong filamentation of the vortex interior. During January, February, and March 2003 flights of the Russian high-altitude aircraft Geophysica were performed in order to probe the vortex, filaments and in one case the merging zone between the secondary vortices. Comparisons between CLaMS results and observations obtained from the Geophysica flights show in general good agreement. Several areas affected by both transport and strong mixing could be identified, allowing explanation of many of the structures observed during the flights. Furthermore, the CLaMS simulations allow for a quantification of the air mass exchange between mid latitudes and the vortex interior. The simulation suggests that after the formation of the vortex was completed, its interior remaind relatively undisturbed. Only during the two re-merging events were substantial amounts of extra-vortex air transported into the polar vortex. When in March the vortex starts weakening additional influence from lower latitudes becomes apparent in the model results. In the lower stratosphere export of vortex air leads only to a fraction of about 5% polar air in mid latitudes by the end of March. An upper limit for the contribution of ozone depleted vortex air on mid-latitude ozone loss is derived, indicating that the maximum final impact of dilution is on the order of 50%.
From July 2002 to March 2004 the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) aboard the European Space Agency´s Environmental Satellite (Envisat) measured nearly continuously mid infrared limb radiance spectra. These measurements are utilised to retrieve the global distribution of the chlorofluorocarbon CFC-11 by applying a new fast forward model for Envisat MIPAS and an accompanying optimal estimation retrieval processor. A detailed analysis shows that the total retrieval errors of the individual CFC-11 volume mixing ratios are typically below 10% in the altitude range 10 to 25 km and that the systematic components dominate. Contribution of a priori information to the retrieval results are less than 5 to 10% and the vertical resolution of the observations is about 3 to 4 km in the same vertical range. The data are successfully validated by comparison with several other space experiments, an air-borne in-situ instrument, measurements from ground-based networks, and independent Envisat MIPAS analyses. The retrieval results from 425 000 Envisat MIPAS limb scans are compiled to provide a new climatological data set of CFC-11. The climatology shows significantly lower CFC-11 abundances in the lower stratosphere compared with the Reference Atmospheres for MIPAS (RAMstan V3.1) climatology. Depending on the atmospheric conditions the differences between the climatologies are up to 30 to 110 ppt (45 to 150%) at 19 to 27 km altitude. Additionally, time series of CFC-11 mean abundance and variability for five latitudinal bands are presented. The observed CFC-11 distributions can be explained by the residual mean circulation and large-scale eddy-transports in the upper troposphere and lower stratosphere. The new CFC-11 data set is well suited for further scientific studies.
Global distributions of profiles of sulphur hexafluoride (SF6) have been retrieved from limb emission spectra recorded by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat covering the period September 2002 to March 2004. Individual SF6 profiles have a precision of 0.5 pptv below 25 km altitude and a vertical resolution of 4–6 km up to 35 km altitude. These data have been validated versus in situ observations obtained during balloon flights of a cryogenic whole-air sampler. For the tropical troposphere a trend of 0.230±0.008 pptv/yr has been derived from the MIPAS data, which is in excellent agreement with the trend from ground-based flask and in situ measurements from the National Oceanic and Atmospheric Administration Earth System Research Laboratory, Global Monitoring Division. For the data set currently available, based on at least three days of data per month, monthly 5° latitude mean values have a 1 o standard error of 1%. From the global SF6 distributions, global daily and monthly distributions of the apparent mean age of air are inferred by application of the tropical tropospheric trend derived from MIPAS data. The inferred mean ages are provided for the full globe up to 90° N/S, and have a 1 o standard error of 0.25 yr. They range between 0 (near the tropical tropopause) and 7 years (except for situations of mesospheric intrusions) and agree well with earlier observations. The seasonal variation of the mean age of stratospheric air indicates episodes of severe intrusion of mesospheric air during each Northern and Southern polar winter observed, long-lasting remnants of old, subsided polar winter air over the spring and summer poles, and a rather short period of mixing with midlatitude air and/or upward transport during fall in October/November (NH) and April/May (SH), respectively, with small latitudinal gradients, immediately before the new polar vortex starts to form. The mean age distributions further confirm that SF6 is destroyed in the mesosphere to a considerable degree. Model calculations with the Karlsruhe simulation model of the middle atmosphere (KASIMA) chemical transport model agree well with observed global distributions of the mean age only if the SF6 sink reactions in the mesosphere are included in the model.
This study presents an evaluation of a pulse height condensation particle counter (PH-CPC) and an expansion condensation particle counter (E-CPC) in terms of measuring ambient and laboratory-generated molecular and ion clusters. Ambient molecular cluster concentrations were measured with both instruments as they were deployed in conjunction with an ion spectrometer and other aerosol instruments in Hyytiälä, Finland at the SMEAR II station between 1 March and 30 June 2007. The observed cluster concentrations varied and ranged from some thousands to 100 000 cm -3. Both instruments showed similar (within a factor of ~5) concentrations. An average size of the detected clusters was approximately 1.8 nm. As the atmospheric measurement of sub 2-nm particles and molecular clusters is a challenging task, we conclude that most likely we were unable to detect the smallest clusters. Nevertheless, the reported concentrations are the best estimates to date for minimum cluster concentrations in a boreal forest environment.
We report the first atmospheric observations of the Chlorofluorocarbons (CFCs) trifluorochloroethene, 3-chloropentafluoropropene and 4,4-dichlorohexafluoro-1-butene by means of Gas Chromatography with Electron Capture and Mass Spectrometric detection (GC-ECD-MS) in air samples taken at the Taunus Observatory operated by the University of Frankfurt (Main) and the Jungfraujoch High Altitude Research Station in Switzerland. These substances belong to a class of CFCs containing a double bond and are suspected to originate from the production and thermal degradation of widely used fluoropolymers like polychlorotrifluoroethene (PCTFE). Their atmospheric lifetimes are expected to be rather short. A quantitative calibration could only be derived for trifluorochloroethene but not for the other species by now. Thus, we use a relative sensitivity method to get a first indication of the observed atmospheric abundances. Identification was possible because of an air plume containing high concentrations of these substances. We suggest that the abundances found on this occasion originated from a local source. However, we have also observed the novel CFCs in air masses representative of background conditions, though with much lower concentrations. These species and some of their degradation products are toxic and could also be relevant for stratospheric and tropospheric ozone depletion.
Assessment of ecologically relevant hydrological change in China due to water use and reservoirs
(2008)
As China’s economy booms, increasing water use has significantly affected hydro-geomorphic processes and thus the ecology of surface waters. A large variety of hydrological changes arising from human activities such as reservoir construction and management, water abstraction, water diversion and agricultural land expansion have been sustained throughout China. Using the global scale hydrological and water use model WaterGAP, natural and anthropogenically altered flow conditions are calculated, taking into account flow alterations due to human water consumption and 580 large reservoirs. The impacts resulting from water consumption and reservoirs have been analyzed separately. A modified “Indicators of Hydrologic Alteration” approach is used to describe the human pressures on aquatic ecosystems due to anthropogenic alterations in river flow regimes. The changes in long-term average river discharge, average monthly mean discharge and coefficients of variation of monthly river discharges under natural and impacted conditions are compared and analyzed. The indicators show very significant alterations of natural river flow regimes in a large part of northern China and only minor alterations in most of southern China. The detected large alterations in long-term average river discharge, the seasonality of flows and the inter-annual variability in the northern half of China are very likely to have caused significant ecological impacts.
Transcriptional activation involves the ordered recruitment of coactivators via direct interactions between distinct binding domains and recognition motifs. The p160/SRC/NCoA coactivator family comprises three members (NCoA-1, -2 and -3), which are organized in multiprotein coactivator complexes. We had identified the PAS-B domain of NCoA-1 as an LXXLL motif binding domain. Here we show that NCoA family members are able to interact with other full-length NCoA proteins via their PAS-B domain and they specifically interact with the CBP-interaction domain (CID/AD1) of NCoA-1. Peptide competition, binding experiments and mutagenesis of LXXLL motifs point at distinct binding motif specificities of the NCoA PAS-B domains. NMR studies of different NCoA-1-PAS-B/LXXLL peptide complexes revealed similar although not identical binding sites for the CID/AD1 and STAT6 transactivation domain LXXLL motifs. In mechanistic studies, we found that overexpression of the PAS-B domain is able to disturb the binding of NCoA-1 to CBP in cells and that a CID/AD1 peptide competes with STAT6 for NCoA-1 in vitro. Moreover, the expression of an endogenous androgen receptor target gene is affected by the overexpression of the NCoA-1 or NCoA-3 PAS-B domains. Our study discloses a new, complementary mechanism for the current model of coactivator recruitment to target gene promoters.
In a combined NMR/MD study, the temperature-dependent changes in the conformation of two members of the RNA YNMG-tetraloop motif (cUUCGg and uCACGg) have been investigated at temperatures of 298, 317 and 325 K. The two members have considerable different thermal stability and biological functions. In order to address these differences, the combined NMR/MD study was performed. The large temperature range represents a challenge for both, NMR relaxation analysis (consistent choice of effective bond length and CSA parameter) and all-atom MD simulation with explicit solvent (necessity to rescale the temperature). A convincing agreement of experiment and theory is found. Employing a principle component analysis of the MD trajectories, the conformational distribution of both hairpins at various temperatures is investigated. The ground state conformation and dynamics of the two tetraloops are indeed found to be very similar. Furthermore, both systems are initially destabilized by a loss of the stacking interactions between the first and the third nucleobase in the loop region. While the global fold is still preserved, this initiation of unfolding is already observed at 317 K for the uCACGg hairpin but at a significantly higher temperature for the cUUCGg hairpin.
In Western Europe pedunculate oak (Quercus robur L.) is the forest tree with the highest number of phytophagous insect species (Yela & Lawton 1997). One of these, the green oak leaf roller Tortrix viridana L. is an oligophagous herbivorous moth with a host range limited to the genus Quercus (Hunter 1990, Du Merle 1999). During outbreaks, T. viridana often leads to defoliation of oaks in spring. The abundance of T. viridana is subject to the population size fluctuations typical for herbivorous insects, where periods of small population sizes (latent periods) alternate with periods of high population sizes (outbreak) (e.g. Schütte 1957, Horstmann 1984). Apart from many experimental studies on population dynamics of the moth (e.g. Hunter 1990, Du Merle 1999, Ivashov & al. 2002) so far little attention has been paid to the genetic variation within the species as an important aspect of the genetics of this host-parasite interaction. Simchuk & al. (1999) found changes in the heterozygosity level of different isozyme loci during outbreaks in T. viridana and molecular markers for T. viridana have been developed for analyses of genetic variation within and among populations (Schroeder & Scholz 2005). But, investigations of genetic variation within and among populations of forest pest species are important to predict future pest outbreaks. So far the processes outbreaks based on are not entirely clarified, however it is known that migration plays a major role. Using molecular markers investigations of the genetic variation are possible and offer the opportunity to analyse distribution events. In this paper first results are presented concerning the genetic variation of the green oak leaf roller at three geographic scales: (1) among trees within a population, (2) among populations at a small spatial scale of about 150 km and (3) among populations at a broader geographic scale up to 3000 km. Furthermore results of the genetic variation of oaks at the small spatial scale are represented.
Since the late 1990s, the oak processionary moth, Thaumetopoea processionea (L.), has been occurring at high population densities in eastern Austria. Particularly, infestations in areas of human settlement have created increasing interest in this insect due to health problems caused by the urticating hairs of the larvae. New methods for biological control are desirable. Like essentially all forest Lepidoptera, T. processionea is host for entomopathogenic microsporidia. These obligatory parasitic protists have been evaluated as biocontrol agents against an other oak pest, Lymantria dispar (Weiser & Novotny, 1987; Jeffords & al., 1988). Life history traits of T. processionea make this insect an even more promising target for the use of microsporidia. The larvae are highly gregarious and stay together in nests made of larval silk for resting periods and molting. Microsporidia utilize several pathways for horizontal transmission that would be aided by these features: spores can be released after host death from cadavers as well as from living larvae via silk or feces. Additionally, many microsporidia are vertically transmitted (summarized in Maddox & al., 1998). In this project, T. processionea larvae from various regions in eastern Austria were screened for the natural occurrence of microsporidia. One isolate, Endoreticulatus sp., was further studied and mass produced in a laboratory host, L. dispar, that is easy to rear and does not pose a health hazard for people working with the insects. An inoculative release was attempted on isolated trees infested with T. processionea.
Cantharidin, which is mainly found in blister beetles (Coleoptera: Meloidae), is one of the most intensively studied natural products of insect (Dettner, 1997; McCormick & Carrel, 1987). The involvement of cantharidin in courtship behaviour has been already confirmed for certain canthariphilous insects (Eisner & al. 1996a,b; Frenzel & Dettner 1994; Frenzel & al. 1992; Schütz & Dettner, 1992; Hemp & al. 1999). The function and intrinsinc role of cantharidin in the courtship behaviour of Meloids has been never fully established. McCormick & Carrel (1987) only suggested that cantharidin might be used by female meloids when selecting a mate at close range. Pinto (1974, 1975) was, in fact, the first to consider male cuticular pores as being involved in the courtship behaviour of species from the genus Linsleya and Tegrodera (Meloidae). Based on morphology and chemical analyses of Cyaneolytta sp. (Coleoptera: Meloidae), we have hereby provided some further evidences that cantharidin may act as an infochemical in courtship behaviour of meloid beetles.
Sexual deception of male bees is one of the most remarkable mechanisms of pollination (Ackermann 1986, Proctor & al. 1996). Flowers of the orchid genus Ophrys mimic females of their pollinator species, usually bees and wasps, to attract males, which try to copulate with the flowers. During this so-called “pseudocopulation” the male removes the pollinia and transfers them to another flower to ensure pollination. Apart from visual and tactile cues, floral scent was shown to be most important for eliciting mating behaviour in males (Kullenberg 1961, Schiestl & al. 1999, Ayasse & al. 2003). Pollination in Ophrys is highly specific and usually each Ophrys species attracts only one pollinator species (Paulus & Gack 1990). The high degree of specialization provides the means of reproductive isolation between the intercrossable Ophrys-species (Ehrendorfer 1980). The complex odour-bouquets released by the flowers are species-specific and often consist of more than 100 different chemical compounds (Borg-Karlson & al. 1985, Ayasse 2006). Speciation in Ophrys-orchids may be brought about by changes in the pollinator attracting floral scent. The attraction of a new pollinator may act as a pre-zygotic isolation barrier (Stebbins 1970, Paulus & Gack 1990, Soliva & al. 2001). We investigated three sympatrically occuring Ophrys-species on Sardinia. O. chestermanii and O. normanii are endemic and are both pollinated by males of the bumblebee B. vestalis. O. tenthredinifera is pollinated by Eucera nigrilabris. There are different opinions concerning the taxonomic status of O. normanii. It has been described as an actual hybrid between O. chestermanii and O. tenthredinifera (Wood 1983). Paulus & Gack (1995) suggested that it is an own species, that either has developed from a hybrid between O. chestermanii and O. normanii or that has evolved by radiation from O. tenthredinifera. By conducting behavioural-tests with B. vestalis males, performing gas chromatographic analyses and electrophysiological studies we wanted to identify pollinator attracting scent and to clarify the taxonomic status of O. normanii.
The orchid genus Epipactis is represented by 25 species in Europe (Richards 1982). Epipactis helleborine (L.) Crantz is the most common and widely distributed species of the genus (Wiefelspütz 1970), and is a prime example for wasp-flowers, because it is mainly pollinated by social wasps (Hymenoptera: Vespidae), like Vespula vulgaris and V. germanica (Müller 1873). Darwin (1888) already noticed that E. helleborine is almost exclusively ignored by bees and bumblebees, an observation that was confirmed in recent investigations (Keppert 2001). The flowers of E. helleborine show morphological, physiological and phenological adaptations to the visit and the pollination by Vespidae (Keppert 2001). They possess a reddish-brown or dirty purple coloration of the inflorescence (Keppert 2001), have relatively small, mostly bulbous blossoms with a broad entrance and bulbous widened, nectar-rich juice holders (Müller 1873, 1881; Schremmer 1962). Although there is much reported about wasp-pollinated flowers there is little known about the signals that are responsible for the attraction of wasps. Wiefelspütz (1970) proclaimed the statement that only the visual stimulus is responsible for the wasp attraction. Recently studies, however, assumed that odour is involved in the wasp attraction (Keppert 2001). Hölzler (2003) showed that the main attraction of the wasp-flower Epipactis for pollinators is its olfactory stimulus. It remains an unanswered question why E. helleborine flowers almost exclusively attracts social wasps, as opposed to bees and bumblebees. In this study we analysed the role of floral volatiles which are responsible for the specific attraction of social wasps. We supposed a mimicry-system in E. helleborine for the specific attraction of pollinators for the following reasons. So-called “green leaf volatiles” (GLVs) are emitted by plants while herbivorous insects, for example caterpillars, feed on them. GLVs thereby attract predators or parasitoids of the herbivorous insects (Dicke & Sabelis 1988; Turlings & al. 1990, 1995; Dicke & Vet 1999). Among the GLVs so far identified in former studies there are aldehydes, compounds that were also found in flower extracts of E. helleborine (Hölzler 2003). Therefore, we postulated that E. helleborine flowers produce GLVs in order to attract prey hunting social wasps for pollination. We performed bioassays and analysed flower odour gained to headspace-sampling using gas chromatography (GC), mass spectrometry (GC-MS) and gas chromatography coupled with electrophysiological analysis (GC-EAD) to investigate the hypothesis that E. helleborine flowers mimic “green leaf volatiles” (GLVs) to attract their pollinators.
Solitary bees are important pollinators of flowers. Besides nectar they collect pollen at flowers mainly to provide their larvae with food. Many bee species collect pollen only on a few closely related plant species (oligolecty) (Müller & al. 1997). Little is known about the visual and olfactorial signals they use for host-plant finding (Wcislo & Cane 1996). However, bees can olfactorily distinguish between different pollen species (von Frisch 1923), and a species-specific chemistry of pollen odour is known for some plant species (Bergström & al. 1995, Dobson & al. 1999). Further, it was shown that naïve oligolectic bees recognize their host-plant on the basis pollen volatiles (Dobson & Bergström 2000) and that flower-experienced bees could use pollen odours to assess pollen availability (Dobson & al. 1999). Besides scent, also visual cues are of relevance for host-plant finding, and bees orientate especially spectral contrasts. Biotests with dummy flowers revealed that colour contrast and not intensity and dominant wavelengths are influencing innate behavioural responses (Lunau 1990). Further it was shown that naïve bumblebees were most motivated to land on a flower when visual stimuli from the antheres are combined with olfactorial stimuli from the pollen (1992). We choose Osmia adunca P., which is highly specialized on Echium L., as a model to investigate the importance of floral cues for an oligolectic bee. Because bees learn to associate odours with reward more rapidly than visual cues (Menzel 1985), we hypothesize that scent plays a major role in attraction flower-experienced O. adunca females. We used gas chromatography to compare the scent of three Echium species with the scent of a closely related Anchusa species, and a spectrometer to compare the colour of the three Echium species. Additionally we conducted a biotest to determine the importance of visual and olfactorial signals of Echium for host-plant finding of experienced O. adunca females.
In agroecological research it has been appreciated only fairly recently that plant-insect interactions and other ecological processes depend on scales much larger than a single habitat (Wiens et al. 1997). Crop-pest interactions have mainly been studied on single pest species by focusing either on the impact of field parameters or on landscape structure but only rarely included both factors (Östman et al. 2001). Here we investigated how the abundances of three major insect pest species in oilseed rape (OSR) responded to field parameters and landscape characteristics at various spatial scales. Pest species considered in the current study include (i) ceutorhynchid stem weevils that lay eggs in leaf petioles or midribs of OSR plants while the larvae tunnel in the stems; (ii) pollen beetles that feed on pollen and destroy flower buds and (iii) brassica pod midge that lay eggs into OSR pods where the hatched larvae consume the seeds as well as tissue of the pod walls and cause the pods to split prematurely (Alford et al. 2003). Studying these different groups of pests is especially important because they attack different parts of the crop, use different habitats as overwintering sites and also differ in their mobility; with the exception of pollen beetles these pest species have never been studied in a landscape context. The specific objectives of this study were to determine (i) whether the major OSR pest species differ in their relation to field and landscape characteristics and (ii) at which spatial scales landscape variables are effective.
Agricultural intensification is a major threat to biological diversity worldwide. Land management activities enhancing landscape diversity are therefore regarded as a key strategy to halt species loss in cultural landscapes. Diverse and abundant communities of predatory arthropods, e.g. spiders (Araneae), have a high potential to suppress pest populations (Symondson et al. 2002) and could therefore contribute to allow reductions of pesticide use. Crop fields alone are usually not able to sustain diverse and individual-rich populations of predatory arthropods, because agricultural management results in disturbances and habitat deteriorations (harvest, soil cultivation, pesticide application) that kill or drive away large parts of the populations. Therefore semi-natural and perennial habitats in agricultural landscapes are considered to be of great importance for beneficial arthropods. On the one hand they offer refuge habitats in times when arable fields are hostile, e.g. fields with bare grounds during winter (Schmidt & Tscharntke 2005). On the other hand, viable populations of predatory arthropods in semi-natural habitats can serve as sources for (re-) colonisation of arable fields (Schmidt & Tscharntke 2005). Because of these exchanges between crop and non-crop areas it is important to include the surrounding landscape when investigating field-scale processes. We investigated the relations between spider assemblages in arable fields and the surrounding landscape in 29 fields of winter oilseed rape (OSR) in an agricultural landscape in eastern Austria. The objectives of this study were to estimate (1) how much spider assemblages in oilseed rape fields are influenced by the surrounding landscape, (2) the relative influence of landscape variables compared to field-scale variables and (3) at which spatial scales landscape variables are effective.
The lower wood-feeding Australian termite Mastotermes darwiniensis Froggatt (Fig. 1) is the only living member of the family Mastotermitidae. The complex symbiotic hindgut flora consists of protozoa (formerly named Archaezoa; Cleveland & Grimstone 1964; Brugerolle & al. 1994; Berchtold & König 1995; Fröhlich & König 1999a, b), bacteria (Berchtold & König 1996; Berchtold & al. 1999), archaea (Fröhlich & König 1999a, b) and yeasts (Prillinger & al. 1996; Schäfer & al. 1996). The digestive system of Mastotermes darwiniensis consists of the foregut with the crop and the gizzard, the midgut, and the hindgut (Noirot & Noirot-Timothée 1969; 1995). The hindgut consists of five segments (P1 – P5): the proctodeal segment, the enteric valve, the paunch, the colon and the rectum. The paunch is the main microbial fermentation chamber, but the colon also contains microorganisms. The paunch is subdivided into a dilated thin-walled region (P3a) and a thick walled more tubular region (P3b) (Fig. 1c). In the case of Mastotermes darwiniensis oxygen diffusion gradients could be detected up to 100 μm below the epithelium (Berchtold & al., 1999).
In our present-day landscape in Central Europe major parts of the xylobiontic especially of the saproxylic beetle fauna belong to the group of endangered species assemblages (Speight 1989, Geiser 1994). Oaks, in Central Europe mainly Quercus robur and Q. petraea, are well known for their large number of associated insect species and harbour the highest beetle diversity, especially for dead wood inhabiting species, of all broadleaved tree species in this region (e.g. Palm 1959). A characteristic species associated with oaks in its life-cycle is the endangered Great Capricorn Cerambyx cerdo. C. cerdo is one of the protected species explicitly named in the Habitats Directive of the European Union with the goal of maintaining existing populations and establishing long-term survival (Council of the European Communities 1992). The last remaining colonised areas of this longhorn beetle in Central Europe are well known for the enormous number of very rare xylobiontic beetle species. Thus, we are interested in the following research questions: 1) Are there typical species associated with C. cerdo? 2) If so, what kind of relationship do these associated species have to C. cerdo from a nature conservation point of view?
A high-precision pressure probe is described which allows non-invasive online-monitoring of the water relations of intact leaves. Real-time recording of the leaf water status occurred by data transfer to an Internet server. The leaf patch clamp pressure probe measures the attenuated pressure, Pp, of a leaf patch in response to a constant clamp pressure, Pclamp. Pp is sensed by a miniaturized silicone pressure sensor integrated into the device. The magnitude of Pp is dictated by the transfer function of the leaf, Tf, which is a function of leaf patch volume and ultimately of cell turgor pressure, Pc, as shown theoretically. The power function Tf=f(Pc) theoretically derived was experimentally confirmed by concomitant Pp and Pc measurements on intact leaflets of the liana Tetrastigma voinierianum under greenhouse conditions. Simultaneous Pp recordings on leaflets up to 10 m height above ground demonstrated that changes in Tf induced by Pc changes due to changes of microclimate and/or of the irrigation regime were sensitively reflected in corresponding changes of Pp. Analysis of the data show that transpirational water loss during the morning hours was associated with a transient rise in turgor pressure gradients within the leaflets. Subsequent recovery of turgescence during the afternoon was much faster than the preceding transpiration-induced water loss if the plants were well irrigated. Our data show the enormous potential of the leaf patch clamp pressure probe for leaf water studies including unravelling of the hydraulic communication between neighbouring leaves and over long distances within tall plants (trees).
Chloroplast function depends on the translocation of cytosolically synthesized precursor proteins into the organelle. The recognition and transfer of most precursor proteins across the outer membrane depend on a membrane inserted complex. Two receptor components of this complex, Toc34 and Toc159, are GTPases, which can be phosphorylated by kinases present in the hosting membrane. However, the physiological function of phosphorylation is not yet understood in detail. It is demonstrated that both receptors are phosphorylated within their G-domains. In vitro, the phosphorylation of Toc34 disrupts both homo- and heterodimerization of the G-domains as determined using a phospho-mimicking mutant. In endogenous membranes this mutation or phosphorylation of the wild-type receptor disturbs the association of Toc34, but not of Toc159 with the translocation pore. Therefore, phosphorylation serves as an inhibitor for the association of Toc34 with other components of the complex and phosphorylation can now be discussed as a mechanism to exchange different isoforms of Toc34 within this ensemble.
Gene trapping is used to introduce insertional mutations into genes of mouse embryonic stem cells (ESCs). It is performed with gene trap vectors that simultaneously mutate and report the expression of the endogenous gene at the site of insertion and provide a DNA tag for rapid identification of the disrupted gene. Gene traps have been employed worldwide to assemble libraries of mouse ESC lines harboring mutations in single genes, which can be used to make mutant mice. However, most of the employed gene trap vectors require gene expression for reporting a gene trap event and therefore genes that are poorly expressed may be under-represented in the existing libraries. To address this problem, we have developed a novel class of gene trap vectors that can induce gene expression at insertion sites, thereby bypassing the problem of intrinsic poor expression. We show here that the insertion of the osteopontin enhancer into several conventional gene trap vectors significantly increases the gene trapping efficiency in high-throughput screens and facilitates the recovery of poorly expressed genes.
Comparative studies suggest that at least some bird species have evolved mental skills similar to those found in humans and apes. This is indicated by feats such as tool use, episodic-like memory, and the ability to use one´s own experience in predicting the behavior of conspecifics. It is, however, not yet clear whether these skills are accompanied by an understanding of the self. In apes, self-directed behavior in response to a mirror has been taken as evidence of self-recognition. We investigated mirror-induced behavior in the magpie, a songbird species from the crow family. As in apes, some individuals behaved in front of the mirror as if they were testing behavioral contingencies. When provided with a mark, magpies showed spontaneous mark-directed behavior. Our findings provide the first evidence of mirror self-recognition in a non-mammalian species. They suggest that essential components of human self-recognition have evolved independently in different vertebrate classes with a separate evolutionary history.
Ribosome biogenesis in eukaryotes requires the participation of a large number of ribosome assembly factors. The highly conserved eukaryotic nucleolar protein Nep1 has an essential but unknown function in 18S rRNA processing and ribosome biogenesis. In Saccharomyces cerevisiae the malfunction of a temperature-sensitive Nep1 protein (nep1-1ts) was suppressed by the addition of S-adenosylmethionine (SAM). This suggests the participation of Nep1 in a methyltransferase reaction during ribosome biogenesis. In addition, yeast Nep1 binds to a 6-nt RNA-binding motif also found in 18S rRNA and facilitates the incorporation of ribosomal protein Rps19 during the formation of pre-ribosomes. Here, we present the X-ray structure of the Nep1 homolog from the archaebacterium Methanocaldococcus jannaschii in its free form (2.2 Å resolution) and bound to the S-adenosylmethionine analog S-adenosylhomocysteine (SAH, 2.15 Å resolution) and the antibiotic and general methyltransferase inhibitor sinefungin (2.25 Å resolution). The structure reveals a fold which is very similar to the conserved core fold of the SPOUT-class methyltransferases but contains a novel extension of this common core fold. SAH and sinefungin bind to Nep1 at a preformed binding site that is topologically equivalent to the cofactor-binding site in other SPOUT-class methyltransferases. Therefore, our structures together with previous genetic data suggest that Nep1 is a genuine rRNA methyltransferase.
Bency Eichorn learns in kollel and, on the side, has been researching about various segulos. For his wedding he authored a book, Simchas Zion, discussing the segulah of keeping the afikomom from year-to-year. The post below is a small part of a much larger project on this segulah and has been adapted for the blog.
Market uptake of pegylated interferons for the treatment of hepatitis C in Europe : meeting abstract
(2008)
Introduction and Objectives Hepatitis C virus (HCV) infection is a leading cause of chronic liver disease with life threatening sequelae such as end-stage liver cirrhosis and liver cancer. It is estimated that the infection annually causes about 86,000 deaths, 1.2 million disability adjusted life years (DALYs), and ¼ of the liver transplants in the WHO European region. Presently, only antiviral drugs can prevent the progression to severe liver disease. Pegylated interferons combined with ribavirin are considered as current state-of-the-art treatment. Objective of this investigation was to assess the market uptake of these drugs across Europe in order to find out whether there is unequal access to optimised therapy. Material and Methods We used IMS launch and sales data (April 2000 to December 2005) for peginterferons and ribavirin for 21 countries of the WHO European region. Market uptake was investigated by comparing the development of country-specific sales rates. For market access analysis, we converted sales figures into numbers of treated patients and related those to country-specific hepatitis C prevalence. To convert sales figures into patient figures, the amount of active pharmaceutical ingredients (API) sold was divided by average total patient doses (ATPD), derived by a probability tree-based calculation algorithm accounting for genotype distribution, early stopping rules, body weight, unscheduled treatment stops and dose reductions Ntotal=APIPegIFNalpha-2a/ATPDPegIFNalpha-2a+APIPegIFN&alpha-2b/ATPDPegIFNalpha-2b For more concise result presentation the 21 included countries were aggregated into four categories: 1. EU founding members (1957): Belgium, France, Germany, Italy and Netherlands; 2. Countries joining EU before 2000: Austria (1995), Denmark (1973), Finland (1995), Greece (1981), Republic of Ireland (1973), Spain (1986), Sweden and UK (1973) 3. Countries joining EU after 2000: Czech Republic (2004), Hungary (2004), Poland (2004) and Romania (2007); 4. EU non-member states: Norway, Russia, Switzerland and Turkey. Results Market launch and market uptake of the investigated drugs differed considerably across countries. The earliest, most rapid and highest increases in sales rates were observed in the EU founding member states, followed by countries that joined the EU before 2000, countries that joined the EU after 2000, and EU non-member states. Most new EU member states showed a noticeable increase in sales after joining the EU. Market access analysis yielded that until end of 2005, about 308 000 patients were treated with peginterferon in the 21 countries. Treatment rates differed across Europe. The number of patients ever treated with peginterferon per 100 prevalent cases ranged from 16 in France to less than one in Romania, Poland, Greece and Russia. Discussion Peginterferon market uptake and prevalence adjusted treatment rates were found to vary considerably across 21 countries in the WHO European region suggesting unequal access to optimised therapy. Poor market access was especially common in low-resource countries. Besides budget restrictions, national surveillance and prevention policy should be considered as explanations for market access variation. Although our results allowed for the ranking of countries in order of market access, no final conclusions on over- or undertreatment can be drawn, because the number of patients who really require antiviral treatment is unknown. Further research based on pan-European decision models is recommended to determine the fraction of not yet successfully treated but treatable patients among those ever diagnosed with HCV. ...
Many new gene copies emerged by gene duplication in hominoids, but little is known with respect to their functional evolution. Glutamate dehydrogenase (GLUD) is an enzyme central to the glutamate and energy metabolism of the cell. In addition to the single, GLUD-encoding gene present in all mammals (GLUD1), humans and apes acquired a second GLUD gene (GLUD2) through retroduplication of GLUD1, which codes for an enzyme with unique, potentially brain-adapted properties. Here we show that whereas the GLUD1 parental protein localizes to mitochondria and the cytoplasm, GLUD2 is specifically targeted to mitochondria. Using evolutionary analysis and resurrected ancestral protein variants, we demonstrate that the enhanced mitochondrial targeting specificity of GLUD2 is due to a single positively selected glutamic acid-to-lysine substitution, which was fixed in the N-terminal mitochondrial targeting sequence (MTS) of GLUD2 soon after the duplication event in the hominoid ancestor ~18–25 million years ago. This MTS substitution arose in parallel with two crucial adaptive amino acid changes in the enzyme and likely contributed to the functional adaptation of GLUD2 to the glutamate metabolism of the hominoid brain and other tissues. We suggest that rapid, selectively driven subcellular adaptation, as exemplified by GLUD2, represents a common route underlying the emergence of new gene functions.
C2-symmetric bisamidines : chiral Brønsted bases catalysing the Diels-Alder reaction of anthrones
(2008)
C2-symmetric bisamidines 8 have been tested as chiral Brønsted bases in the Diels- Alder reaction of anthrones and N-substituted maleimides. High yields of cycloadducts and significant asymmetric inductions up to 76% ee are accessible. The proposed mechanism involves proton transfer between anthrone and bisamidine, association of the resulting ions and finally a cycloaddition step stereoselectively controlled by the chiral ion pair.
Oscillatory activity in human electro- or magnetoencephalogram has been related to cortical stimulus representations and their modulation by cognitive processes. Whereas previous work has focused on gamma-band activity (GBA) during attention or maintenance of representations, there is little evidence for GBA reflecting individual stimulus representations. The present study aimed at identifying stimulus-specific GBA components during auditory spatial short-term memory. A total of 28 adults were assigned to 1 of 2 groups who were presented with only right- or left-lateralized sounds, respectively. In each group, 2 sample stimuli were used which differed in their lateralization angles (15° or 45°) with respect to the midsagittal plane. Statistical probability mapping served to identify spectral amplitude differences between 15° versus 45° stimuli. Distinct GBA components were found for each sample stimulus in different sensors over parieto-occipital cortex contralateral to the side of stimulation peaking during the middle 200–300 ms of the delay phase. The differentiation between "preferred" and "nonpreferred" stimuli during the final 100 ms of the delay phase correlated with task performance. These findings suggest that the observed GBA components reflect the activity of distinct networks tuned to spatial sound features which contribute to the maintenance of task-relevant information in short-term memory.
Cytotoxic T-lymphocytes play an important role in the protection against viral infections, which they detect through the recognition of virus-derived peptides, presented in the context of MHC class I molecules at the surface of the infected cell. The transporter associated with antigen processing (TAP) plays an essential role in MHC class I–restricted antigen presentation, as TAP imports peptides into the ER, where peptide loading of MHC class I molecules takes place. In this study, the UL49.5 proteins of the varicelloviruses bovine herpesvirus 1 (BHV-1), pseudorabies virus (PRV), and equine herpesvirus 1 and 4 (EHV-1 and EHV-4) are characterized as members of a novel class of viral immune evasion proteins. These UL49.5 proteins interfere with MHC class I antigen presentation by blocking the supply of antigenic peptides through inhibition of TAP. BHV-1, PRV, and EHV-1 recombinant viruses lacking UL49.5 no longer interfere with peptide transport. Combined with the observation that the individually expressed UL49.5 proteins block TAP as well, these data indicate that UL49.5 is the viral factor that is both necessary and sufficient to abolish TAP function during productive infection by these viruses. The mechanisms through which the UL49.5 proteins of BHV-1, PRV, EHV-1, and EHV-4 block TAP exhibit surprising diversity. BHV-1 UL49.5 targets TAP for proteasomal degradation, whereas EHV-1 and EHV-4 UL49.5 interfere with the binding of ATP to TAP. In contrast, TAP stability and ATP recruitment are not affected by PRV UL49.5, although it has the capacity to arrest the peptide transporter in a translocation-incompetent state, a property shared with the BHV-1 and EHV-1 UL49.5. Taken together, these results classify the UL49.5 gene products of BHV-1, PRV, EHV-1, and EHV-4 as members of a novel family of viral immune evasion proteins, inhibiting TAP through a variety of mechanisms.
The degradation of the poly(A) tail is crucial for posttranscriptional gene regulation and for quality control of mRNA. Poly(A)-specific ribonuclease (PARN) is one of the major mammalian 3’ specific exo-ribonucleases involved in the degradation of the mRNA poly(A) tail, and it is also involved in the regulation of translation in early embryonic development. The interaction between PARN and the m7GpppG cap of mRNA plays a key role in stimulating the rate of deadenylation. Here we report the solution structures of the cap-binding domain of mouse PARN with and without the m7GpppG cap analog. The structure of the cap-binding domain adopts the RNA recognition motif (RRM) with a characteristic a-helical extension at its C-terminus, which covers the b-sheet surface (hereafter referred to as PARN RRM). In the complex structure of PARN RRM with the cap analog, the base of the N7-methyl guanosine (m7G) of the cap analog stacks with the solvent-exposed aromatic side chain of the distinctive tryptophan residue 468, located at the C-terminal end of the second b-strand. These unique structural features in PARN RRM reveal a novel cap-binding mode, which is distinct from the nucleotide recognition mode of the canonical RRM domains.
We performed a bioinformatical analysis of protein export elements (PEXEL) in the putative proteome of the malaria parasite Plasmodium falciparum. A protein family-specific conservation of physicochemical residue profiles was found for PEXEL-flanking sequence regions. We demonstrate that the family members can be clustered based on the flanking regions only and display characteristic hydrophobicity patterns. This raises the possibility that the flanking regions may contain additional information for a family-specific role of PEXEL. We further show that signal peptide cleavage results in a positional alignment of PEXEL from both proteins with, and without, a signal peptide.
While the adaptor SKAP-55 mediates LFA-1 adhesion on T-cells, it is not known whether the adaptor regulates other aspects of signaling. SKAP-55 could potentially act as a node to coordinate the modulation of adhesion with downstream signaling. In this regard, the GTPase p21ras and the extracellular signal-regulated kinase (ERK) pathway play central roles in T-cell function. In this study, we report that SKAP-55 has opposing effects on adhesion and the activation of the p21ras -ERK pathway in T-cells. SKAP-55 deficient primary T-cells showed a defect in LFA-1 adhesion concurrent with the hyper-activation of the ERK pathway relative to wild-type cells. RNAi knock down (KD) of SKAP-55 in T-cell lines also showed an increase in p21ras activation, while over-expression of SKAP-55 inhibited activation of ERK and its transcriptional target ELK. Three observations implicated the p21ras activating exchange factor RasGRP1 in the process. Firstly, SKAP-55 bound to RasGRP1 via its C-terminus, while secondly, the loss of binding abrogated SKAP-55 inhibition of ERK and ELK activation. Thirdly, SKAP-55−/− primary T-cells showed an increased presence of RasGRP1 in the trans-Golgi network (TGN) following TCR activation, the site where p21ras becomes activated. Our findings indicate that SKAP-55 has a dual role in regulating p21ras-ERK pathway via RasGRP1, as a possible mechanism to restrict activation during T-cell adhesion.
Diabrotica virgifera virgifera LeConte, in its original North American habitat also known as western corn rootworm beetle, actively continues its expansion to new territories and uses Homo sapiens as its prime vector. It took only 15 years to spread to and occupy the southeastern and central parts of Europe, so far with the exception of Denmark where it has not been documented as of 2007. Economic thresholds have been reached and surpassed only in Southeast European countries like Slovakia, Hungary, Serbia, Eastern Croatia, Romania and Northern Italy. But both, the area affected and the severity of symptoms are increasing. Model calculations by a number of authors (Baufeld & Enzian, 2005 a and b; Hongmei Li & al. 2006, CLIMEX model) indicate a definitive propensity of D. v. virgifera to expand its currently occupied territory to regions with moderate temperatures and Zea mays cultivation. East Africa and Eastern Asia are included in the list of potential candidates for future inadvertent introduction. In most discussions it is tacitly and erroneously assumed that Z. mays is the only or the only important host of D. v. virgifera. Our recent observations in Eastern Slovenia on the oil pumpkin Cucurbita pepo indicate, however, that this simplifying assumption is notlonger strictly valid. It has to be modified in light of new evidence. Here, we report a few field experiments conducted in August of 2006 clarifying the host status of C. pepo in a European country.
The codling moth, Cydia pomonella (Lep., Tortricidae), is a significant pest of orchard crops such as apple and pear in Southern Germany, and can cause severe economic damage to apple crops. Due to resistance to conventional pesticides and the growing market for organic fruit, Cydia pomonella Granulovirus (CpGV) has been used to control C. pomonella in Germany for over 10 years. Recently, populations exhibiting resistance to CpGV have been reported. In this study, we have used amplified fragment length polymorphism (AFLP) markers to estimate genetic variations between eight different C. pomonella populations, which were obtained from different locations exhibiting varying levels of resistance to CpGV. Three different AFLP primer combinations generated a total of 194 AFLP fragments, ranging from 57.84 to 424.11 bp, with an average of 59.23 amplified fragments per primer combination. The total number of segregating fragments ranged from 181 to 115 and resulted in a high loci polymorphism of 100% in most cases, except for two populations, where it was found to be 88.1% and 93.3%. An analysis of genetic variation based on the obtained AFLP markers resulted in high gene diversity (Hj) values, ranging between 0.2884 to 0.3508. Hj values also indicated a loss in gene diversity within a population over time. The Wright Fixation Index (FST) values indicated a low to moderate genetic differentiation in the populations. The cluster analysis (UPGMA), based on genetic distance values, showed that the majority of C. pomonella populations from different locations were clearly distributed into distinct groups and showed a large genetic variability.
The bee fauna of Taiwan was studied intensively in the first half of last century and was based in large parts on the extensive material collected by Hans Sauter between 1902 and 1914. Subsequent studies on bees of Taiwan have only been sporadic. Within a cooperation between the above mentioned institutions the bee fauna was reinvestigated. It was shown how insufficiently the bee fauna of Taiwan had been investigated so far, in particular, the higher mountain regions. Now about 150 species of bees, belonging to 32 different genera, are known from Taiwan, ten of which have been described or recognized as new for science by the recent cooperation.
Taxonomic, systematic, and biogeography knowledge on the Palaearctic species of Pristaulacus Kieffer 1900 is summarized. Twenty-one valid species are recognized. The most important morphological characters taken into consideration are: shape, cuticular sculpture, and pubescence of head; index length/width of antennomeres; shape, sculpture and cuticular processes of mesosoma, especially of pronotum and mesonotum; number and shape of teeth on claw; shape and sculpture of metasoma; ovipositor length compared with wing and antenna length; and colour pattern (e.g., the dark spots on fore wing, and the colour of hind tarsus). Several characters of the genital capsule of the male were proved to be very useful for species identification, e.g., the shape of the paramere, volsella, cuspis, and digitus. Based on analysis of twenty-five morphological characters, eight species groups are recognized. The critical revision of the chorological data, including many new records, introduced relevant changes of the geographical distribution pattern of most species. Twelve species are restricted to the western part of the Palaearctic Region and eight species are restricted to its eastern part; only one species, P. gibbator, has a wider distribution, including both western and eastern parts of the Palaearctics.
Rising atmospheric CO2 is regarded as the main driver of global warming (Crowley, 2000). While temperature changes directly affect plants and animals (Root et al., 2003; Parmesan, 2006), the effects of CO2 on herbivores are mediated through changes in nutrient quality. Elevated concentrations of atmospheric CO2 are likely to increase photosynthetic activity and thus provide more C-based compounds which may alter plant chemical profiles and plant–herbivore–natural enemy interactions. There are several scenarios how insects will react when confronted with a different food quality. A nutrient poor diet, induced by nitrogen dilution, may result in compensatory feeding with either no adverse effects on insect performance or with negative effects on insect growth due to low digestibility of plant structural compounds (e.g. lignin) or toxic effects of secondary metabolites (e.g. tannins). Here we present data from on-tree feeding trials with larvae of the generalist herbivore Lymantria dispar and one of its natural enemies, the hymenopteran endoparasitoid Glyptapanteles liparidis, studied in 2005. The experiments were conducted at the Swiss free-air CO2 enrichment (FACE) site near Basel, in an approximately 80-100-yr-old, mixed-species forest. The data link changes in foliar chemistry of three tree species (Quercus petraea, Fagus sylvatica, Carpinus betulus) exposed to 540 ppm CO2 with herbivore and parasitoid performance.
The impact of European integration on the German system of pharmaceutical product authorization
(2008)
The European Union has evolved since 1965 into an influential political player in the regulation of pharmaceutical safety standards. The objective of establishing a single European market for pharmaceuticals makes it necessary for member-states to adopt uniform safety standards and marketing authorization procedures. This article investigates the impact of the European integration process on the German marketing authorization system for pharmaceuticals. The analysis shows that the main focal points and objectives of European regulation of pharmaceutical safety have shifted since 1965. The initial phase saw the introduction of uniform European safety standards as a result of which Germany was obliged to undertake “catch-up” modernization. From the mid-1970s, these standards were extended and specified in greater detail. Since the mid-1990s, a process of reorientation has been under way. The formation of the European Agency for the Evaluation of Medicinal Products (EMEA) and the growing importance of the European authorization procedure, combined with intensified global competition on pharmaceutical markets, are exerting indirect pressure for EU member-states to adjust their medicines policies. Consequently, over the past few years Germany has been engaged in a competition-oriented reorganization of its pharmaceutical product authorization system the outcome of which will be to give higher priority to economic interests.
We study the responses of residential property and equity prices, inflation and economic activity to monetary policy shocks in 17 countries, using data spanning 1986-2006, using single-country VARs and panel VARs in which we distinguish between groups of countries depending on their financial systems. The effect of monetary policy on property prices is about three times as large as its impact on GDP. Using monetary policy to guard against financial instability by offsetting asset-price movements thus has sizable effects on economic activity. While the financial structure influences the impact of policy on asset prices, its importance appears limited.
This paper explores the role of trade integration—or openness—for monetary policy transmission in a medium-scale New Keynesian model. Allowing for strategic complementarities in price-setting, we highlight a new dimension of the exchange rate channel by which monetary policy directly impacts domestic inflation. Although the strength of this effect increases with economic openness, it also requires that import prices respond to exchange rate changes. In this case domestic producers find it optimal to adjust their prices to exchange rate changes which alter the domestic currency price of their foreign competitors. We pin down key parameters of the model by matching impulse responses obtained from a vector autoregression on U.S. time series relative to an aggregate of industrialized countries. While we find evidence for strong complementarities, exchange rate pass-through is limited. Openness has therefore little bearing on monetary transmission in the estimated model.
Bayesian learning provides the core concept of processing noisy information. In standard Bayesian frameworks, assessing the price impact of information requires perfect knowledge of news’ precision. In practice, however, precision is rarely dis- closed. Therefore, we extend standard Bayesian learning, suggesting traders infer news’ precision from magnitudes of surprises and from external sources. We show that interactions of the different precision signals may result in highly nonlinear price responses. Empirical tests based on intra-day T-bond futures price reactions to employment releases confirm the model’s predictions and show that the effects are statistically and economically significant.
The popular Nelson-Siegel (1987) yield curve is routinely fit to cross sections of intra-country bond yields, and Diebold and Li (2006) have recently proposed a dynamized version. In this paper we extend Diebold-Li to a global context, modeling a potentially large set of country yield curves in a framework that allows for both global and country-specific factors. In an empirical analysis of term structures of government bond yields for the Germany, Japan, the U.K. and the U.S., we find that global yield factors do indeed exist and are economically important, generally explaining significant fractions of country yield curve dynamics, with interesting differences across countries.
Measuring financial asset return and volatilty spillovers, with application to global equity markets
(2008)
We provide a simple and intuitive measure of interdependence of asset returns and/or volatilities. In particular, we formulate and examine precise and separate measures of return spillovers and volatility spillovers. Our framework facilitates study of both non-crisis and crisis episodes, including trends and bursts in spillovers, and both turn out to be empirically important. In particular, in an analysis of nineteen global equity markets from the early 1990s to the present, we find striking evidence of divergent behavior in the dynamics of return spillovers vs. volatility spillovers: Return spillovers display a gently increasing trend but no bursts, whereas volatility spillovers display no trend but clear bursts.
Research with Keynesian-style models has emphasized the importance of the output gap for policies aimed at controlling inflation while declaring monetary aggregates largely irrelevant. Critics, however, have argued that these models need to be modified to account for observed money growth and inflation trends, and that monetary trends may serve as a useful cross-check for monetary policy. We identify an important source of monetary trends in form of persistent central bank misperceptions regarding potential output. Simulations with historical output gap estimates indicate that such misperceptions may induce persistent errors in monetary policy and sustained trends in money growth and inflation. If interest rate prescriptions derived from Keynesian-style models are augmented with a cross-check against money-based estimates of trend inflation, inflation control is improved substantially.
Religious conversion has become a dangerous social and individual problem. In Latin America, a traditional Catholic area, Protestant sects are successfully con-verting more and more Catholics into their own communities. Therefore the Pope demands a strict control of these activities. In India e.g., the Catholic hierarchy is critizising the Indian governments which have forbidden conversion on non-spiritual reasons. Hindu organizations have started even very successfully to re-convert Indian Christians particularly of Dalit and tribal background. Buddhists are very successful in indirect and even direct conversion of many Westerners. Wah-habit missionaries spread their Neo-Islam in the Muslim societies and get more and more even non-Muslim converts. We should add the forcible and sometimes ex-tremely cruel conversions the atheistic states had executed since the last century. ...
In the course of the ME period, HAVE began to encroach on territory previously held by BE. According to Rydén and Brorström (1987); Kytö (1997), this occurred especially in iterative and durational contexts, in the perfect infinitive and modal constructions. In Early Modern English (henceforth EModE), BE was increasingly restricted to the most common intransitives come and go, before disappearing entirely in the 18th and 19th centuries. This development raises a number of questions, both historical and theoretical. First, why did HAVE start spreading at the expense of BE in the first place? Second, why was the change conditioned by the factors mentioned by Rydén and Brorström (1987) and Kytö (1997)? Third, why did the change take on the order of 800 years to go to completion? Fourth, what implications does the change have for general theories of auxiliary selection? In this paper we’ll try to answer the first question by focusing on one the earliest clearly identifiable advance of HAVE onto BE territory – its first appearance with the verb come, which for a number of reasons is an ideal verb to focus on. First, come is by far the most common intransitive verb, so we get large enough numbers for statistical analysis. Second, clauses containing the past participle of come with a form of BE are unambiguous perfects: they cannot be passives, and they did not continue into modern English with a stative reading like he is gone. Third, and perhaps most importantly, come selected BE categorically in the early stages of English, so the first examples we find with HAVE are clear evidence for innovation. We will present evidence from a corpus study showing that the first spread of HAVE was due to a ban on auxiliary BE in certain types of counterfactual perfects, and will propose an account for that ban in terms of Iatridou’s (2000) Exclusion theory of counterfactuals.
Verbs, nouns and affixation
(2008)
What explains the rich patterns of deverbal nominalization? Why do some nouns have argument structure, while others do not? We seek a solution in which properties of deverbal nouns are composed from properties of verbs, properties of nouns, and properties of the morphemes that relate them. The theory of each plus the theory of howthey combine, should give the explanation. In exploring this, we investigate properties of two theories of nominalization. In one, the verb-like properties of deverbal nouns result from verbal syntactic structure (a “structural model”). See, for example, van Hout & Roeper 1998, Fu, Roeper and Borer 1993, 2001, to appear, Alexiadou 2001, to appear). According to the structural hypothesis, some nouns contain VPs and/or verbal functional layers. In the other theory, the verbal properties of deverbal nouns result from the event structure and argument structure of the DPs that they head. By “event structure” we mean a representation of the elements and structure of a linguistic event, not a representation of the world. We refer to this view as the “event model”. According to the event model hypothesis, all derived nouns are represented with the same syntactic structure, the difference lying in argument structure – which in turn is critically related to event structure, in the way sketched in Grimshaw (1990), Siloni (1997) among others. In pursuing these lines of analysis, and at least to some extent disentangling their properties, we reach the conclusion that, with respect to a core set of phenomena, the two theories are remarkably similar – specifically, they achieve success with the same problems, and must resort to the same stipulations to address the remaining issues that we discuss (although the stipulations are couched in different forms).
Class features as probes
(2008)
In this article, we adress (i) the form and (ii) the function on inflection class features in minimalist grammar. The empirical evidence comes from noun inflection systems involving fusional markers in German, Greek, and Russian. As for (i), we argue (based on instances of transparadigmatic syncretism) that class features are not privative; rather, class information must be decomposed into more abstract, binary features. Concerning (ii), we propose that class features qualify as the very device that brings about fusional infection: They are uninterpretable in syntax and actas probes on stems, with matching inflection markers as goels, and thus trigger morphological Agree operations that merge stem and inflection marker before syntax is reached.
Background: Polymorphisms within the insulin gene can influence insulin expression in the pancreas and especially in the thymus, where self-antigens are processed, shaping the T cell repertoire into selftolerance, a process that protects from ß-cell autoimmunity.
Methods: We investigated the role of the -2221Msp(C/T) and -23HphI(A/T) polymorphisms within the insulin gene in patients with a monoglandular autoimmune endocrine disease [patients with isolated type 1 diabetes (T1D, n = 317), Addison´s disease (AD, n = 107) or Hashimoto´s thyroiditis (HT, n = 61)], those with a polyglandular autoimmune syndrome type II (combination of T1D and/or AD with HT or GD, n = 62) as well as in healthy controls (HC, n = 275).
Results: T1D patients carried significantly more often the homozygous genotype "CC" -2221Msp(C/T) and "AA" -23HphI(A/T) polymorphisms than the HC (78.5% vs. 66.2%, p = 0.0027 and 75.4% vs. 52.4%, p = 3.7 × 10-8, respectively). The distribution of insulin gene polymorphisms did not show significant differences between patients with AD, HT, or APS-II and HC.
Conclusion: We demonstrate that the allele "C" of the -2221Msp(C/T) and "A" -23HphI(A/T) insulin gene polymorphisms confer susceptibility to T1D but not to isolated AD, HT or as a part of the APS-II.
Poster presentation A central problem in neuroscience is to bridge local synaptic plasticity and the global behavior of a system. It has been shown that Hebbian learning of connections in a feedforward network performs PCA on its inputs [1]. In recurrent Hopfield network with binary units, the Hebbian-learnt patterns form the attractors of the network [2]. Starting from a random recurrent network, Hebbian learning reduces system complexity from chaotic to fixed point [3]. In this paper, we investigate the effect of Hebbian plasticity on the attractors of a continuous dynamical system. In a Hopfield network with binary units, it can be shown that Hebbian learning of an attractor stabilizes it with deepened energy landscape and larger basin of attraction. We are interested in how these properties carry over to continuous dynamical systems. Consider system of the form Math(1) where xi is a real variable, and fi a nondecreasing nonlinear function with range [-1,1]. T is the synaptic matrix, which is assumed to have been learned from orthogonal binary ({1,-1}) patterns ξμ, by the Hebbian rule: Math. Similar to the continuous Hopfield network [4], ξμ are no longer attractors, unless the gains gi are big. Assume that the system settles down to an attractor X*, and undergoes Hebbian plasticity: T´ = T + εX*X*T, where ε > 0 is the learning rate. We study how the attractor dynamics change following this plasticity. We show that, in system (1) under certain general conditions, Hebbian plasticity makes the attractor move towards its corner of the hypercube. Linear stability analysis around the attractor shows that the maximum eigenvalue becomes more negative with learning, indicating a deeper landscape. This in a way improves the system´s ability to retrieve the corresponding stored binary pattern, although the attractor itself is no longer stabilized the way it does in binary Hopfield networks.
Introduction To investigate the predictive value of clinical and biological markers for a pathological complete remission after a preoperative dose-dense regimen of doxorubicin and docetaxel, with or without tamoxifen, in primary operable breast cancer. Methods Patients with a histologically confirmed diagnosis of previously untreated, operable, and measurable primary breast cancer (tumour (T), nodes (N) and metastases (M) score: T2-3(>= 3 cm) N0-2 M0) were treated in a prospectively randomised trial with four cycles of dose-dense (bi-weekly) doxorubicin and docetaxel (ddAT) chemotherapy, with or without tamoxifen, prior to surgery. Clinical and pathological parameters (menopausal status, clinical tumour size and nodal status, grade, and clinical response after two cycles) and a panel of biomarkers (oestrogen and progesterone receptors, Ki-67, human epidermal growth factor receptor 2 (HER2), p53, bcl-2, all detected by immunohistochemistry) were correlated with the detection of a pathological complete response (pCR). Results A pCR was observed in 9.7% in 248 patients randomised in the study and in 8.6% in the subset of 196 patients with available tumour tissue. Clinically negative axillary lymph nodes, poor tumour differentiation, negative oestrogen receptor status, negative progesterone receptor status, and loss of bcl-2 were significantly predictive for a pCR in a univariate logistic regression model, whereas in a multivariate analysis only the clinical nodal status and hormonal receptor status provided significantly independent information. Backward stepwise logistic regression revealed a response after two cycles, with hormone receptor status and lymph-node status as significant predictors. Patients with a low percentage of cells stained positive for Ki-67 showed a better response when treated with tamoxifen, whereas patients with a high percentage of Ki-67 positive cells did not have an additional benefit when treated with tamoxifen. Tumours overexpressing HER2 showed a similar response to that in HER2-negative patients when treated without tamoxifen, but when HER2-positive tumours were treated with tamoxifen, no pCR was observed. Conclusion Reliable prediction of a pathological complete response after preoperative chemotherapy is not possible with clinical and biological factors routinely determined before start of treatment. The response after two cycles of chemotherapy is a strong but dependent predictor. The only independent factor in this subset of patients was bcl-2. Trial registration number NCT00543829
Background This study was carried out to compare the HRQoL of patients in general practice with differing chronic diseases with the HRQoL of patients without chronic conditions, to evaluate the HRQoL of general practice patients in Germany compared with the HRQoL of the general population, and to explore the influence of different chronic diseases on patients HRQoL, independently of the effects of multiple confounding variables. Methods A cross-sectional questionnaire survey including the SF-36, the EQ-5D and demographic questions was conducted in 20 general practices in Germany. 1009 consecutive patients aged 15–89 participated. The SF-36 scale scores of general practice patients with differing chronic diseases were compared with those of patients without chronic conditions. Differences in the SF-36 scale/summary scores and proportions in the EQ-5D dimensions between patients and the general population were analyzed. Independent effects of chronic conditions and demographic variables on the HRQoL were analyzed using multivariable linear regression and polynomial regression models. Results The HRQoL for general practice patients with differing chronic diseases tended to show more physical than mental health impairments compared with the reference group of patients without. Patients in general practice in Germany had considerably lower SF-36 scores than the general population (P < 0.001 for all) and showed significantly higher proportions of problems in all EQ-5D dimensions except for the self-care dimension (P < 0.001 for all). The mean EQ VAS for general practice patients was lower than that for the general population (69.2 versus 77.4, P < 0.001). The HRQoL for general practice patients in Germany seemed to be more strongly affected by diseases like depression, back pain, OA of the knee, and cancer than by hypertension and diabetes. Conclusion General practice patients with differing chronic diseases in Germany had impaired quality of life, especially in terms of physical health. The independent impacts on the HRQoL were different depending on the type of chronic disease. Findings from this study might help health professionals to concern more influential diseases in primary care from the patient´s perspective.
Background: This article reports on the relationship between cultural influences on life style, coping style, and sleep in a sample of female Portuguese immigrants living in Germany. Sleep quality is known to be poorer in women than in men, yet little is known about mediating psychological and sociological variables such as stress and coping with stressful life circumstances. Migration constitutes a particularly difficult life circumstance for women if it involves differing role conceptions in the country of origin and the emigrant country.
Methods: The study investigated sleep quality, coping styles and level of integration in a sample of Portuguese (N = 48) and Moroccan (N = 64) immigrant women who took part in a structured personal interview.
Results: Sleep quality was poor in 54% of Portuguese and 39% of Moroccan women, which strongly exceeds reports of sleep complaints in epidemiologic studies of sleep quality in German women. Reports of poor sleep were associated with the degree of adoption of a German life style. Women who had integrated more into German society slept worse than less integrated women in both samples, suggesting that non-integration serves a protective function. An unusually large proportion of women preferred an information-seeking (monitoring) coping style and adaptive coping. Poor sleep was related to high monitoring in the Portuguese but not the Moroccan sample.
Conclusion: Sleep quality appears to be severely affected in women with a migration background. Our data suggest that non-integration may be less stressful than integration. This result points to possible benefits of non-integration. The high preference for an information-seeking coping style may be related to the process of migration, representing the attempt at regaining control over an uncontrollable and stressful life situation.
In this paper we compare the distribution of PPs introducing external arguments in nominalizations with PPs introducing external arguments in the verbal domain. We show that several mismatches exist between the behavior of PPs in nominalizations and PPs in the verbal domain. This leads us to suggest that while PPs in the verbal domain are licensed by functional structure alone, within the nominal domain, PPs can also be licensed via an interplay of the encyclopaedic meaning of the root involved and the properties of the preposition itself. This second mechanism kicks in in the absence of functional structure.
Structuring participles
(2008)
In this paper we discuss three types of adjectival participles in Greek, ending in -tos and –menos, and provide a further argument for the view that finer distinctions are necessary in the domain of participles (Kratzer 2001, Embick 2004). We further compare Greek stative participles to their German (and English) counterparts. We propose that a number of semantic as well as syntactic differences shown by these derive from differences in their respective morpho-syntactic composition.
In this paper we investigate the distribution of PPs related to external arguments (agent, causer, instrument, causing event) in Greek. We argue that their distribution supports an analysis, according to which agentive/instrument and causer PPs are licensed by distinct functional heads, respectively. We argue against a conceivable alternative analysis, which links agentivity and causation to the prepositions themselves. We furthermore identify a particular type of Voice head in Greek anticausative realised by non-active Voice morphology.
On the role of syntactic locality in morphological processes : the case of (Greek) derived nominals
(2008)
The paper is structured as follows. In section 2, I briefly summarize the facts on English and Greek nominalizations. In section 3, I discuss English nominal derivation in some detail. In section 4, I turn to the question of licensing of AS in nominals. In section 5, I turn to the issue of the optionality of licensing of AS in the nominal system.
This paper deals with the variable position of adjectives in the Romanian DP. As all other Romance languages, Romanian allows for adjectives to appear in both prenominal and post-nominal position. In addition, however, Romanian has a third pattern: the so-called cel construction, in which the adjective in the post-nominal position is preceded by a determiner-like element, cel. This pattern is superficially similar to Determiner Spreading in Greek. In this paper we contrast the cel construction to Greek DS and discuss the similarities and differences between the two. We then present an analysis of cel as involving an appositive specification clause, building on de Vries (2002). We argue that the same structure is also involved in the context of nominal ellipsis, the second environment in which cel is found.
Pulsed electron-electron double resonance (PELDOR) is a well established method concerning nanometer distance measurements involving two nitroxide spin-labels. In this thesis the applicability of this method to count the number of spins is tested. Furthermore, this work explored the limits, up to which PELDOR data obtained on copper(II)-nitroxide complexes can be quantitatively interpreted. Spin counting provides access to oligomerization studies – monitoring the assembly of homo- or hetero-oligomers from singly labeled compounds. The experimental calibration was performed using model systems, which contain one to four nitroxide radicals. The results show that monomers, dimers, trimers, and tetramers can be distinguished within an error of 5% in the number of spins. Moreover, a detailed analysis of the distance distributions in model complexes revealed that more than one distance can be extracted from complexes bearing several spins, as for example three different distances were resolved in a model tetramer – the other three possible distances being symmetry related. Furthermore, systems exhibiting mixtures of oligomeric states complicate the analysis of the data, because the average number of spin centers contributes nonlinearly to the signal and different relaxation behavior of the oligomers has to be treated explicitly. Experiments solving these problems are proposed in the thesis. Thus, for the first time spin counting has been experimentally calibrated using fully characterized test systems bearing up to four spins. Moreover, the behavior of mixtures was quantitatively interpreted. In addition, it has been shown that several spin-spin distances within a molecule can be extracted from a single dataset. In the second part of the thesis PELDOR experiments on a spin-labeled copper(II)-porphyrin have been quantitatively analyzed. Metal-nitroxide distance measurements are a valuable tool for the triangulation of paramagnetic metal ions. Therefore, X-band PELDOR experiments at different frequencies have been performed. The data exhibits only weak orientation selection, but a fast damping of the oscillation. The experimental data has been interpreted based upon quantitative simulations. The influence of orientation selection, conformational flexibility, spin-density distribution, exchange interaction J, as well as anisotropy and strains of the g-tensor has been examined. An estimate of the spin-density delocalization has been obtained by density functional theory calculations. The dipolar interaction tensor was calculated from the point-charge model, the extension of the point-dipole approximation to several spin bearing centers. Even assuming asymmetric spin distributions induced by an ensemble of asymmetrically distorted porphyrins the effect of delocalization on the PELDOR time trace is weak. The observed damping of dipolar oscillations has been only reproduced by simulations, if a small distribution in J was assumed. It has been shown that the experimental damping of dipolar modulations is not solely due to conformational heterogeneity. In conclusion the quantitative interpretation of PELDOR data is extended to copper-nitroxide- and multi-spin-systems. The influence of the mean distance, of the number of coupled spins, of the conformational flexibility, of spin-density distribution and of the electronic structure of the spin centers has been analyzed using model systems. The insights on model compounds mimicking spin-labeled biomacromolecules – in oligomeric or metal bound states – calibrate the method with respect to the information that can be deduced from the experimental data. The resulting in-depth understanding allows correlating experimental results (from for example biological systems) with models of structure and dynamics. It also opens new fields for PELDOR as for example triangulation of metal centers and oligomerization studies. In general, this thesis has demonstrated that modern pulsed electron paramagnetic resonance techniques in combination with quantitative data analysis can contribute to a detailed insight into molecular structure and dynamics.
Extracts of Boswellia serrata, also known as Indian frankincense, have been used to treat inflammatory diseases in the Indian ayurvedic medicine or Chinese traditional medicine (TCM) for over 3000 years, but the molecular mechanisms of the anti-inflammatory effects are still not well understood. It is obvious that the boswellic acids, the major compounds in the extracts, are responsible for the efficacy. This work employed a protein fishing technique to identify putative targets of boswellic acids at different stages within the inflammatory cascade. For fishing experiments, boswellic acids were immobilized to sepharose and incubated with cell lysates. After washing and boiling, fished proteins were separated by SDS-PAGE and analysed by MALDI-TOF-MS. CatG, DNA-PK and the protein kinase Akt were identified by protein pulldowns with immobilised BAs and characterised as selective and important targets for BAs with an IC50 in the range of physiologically achievable plasma levels up to 5 microM. In addition, the influence on several signal transductions by BAs was tested. Calcium influx, arachidonic acid release, platelet aggregation and TNFalpha-release were assayed to reveal further pharmacological effects of BAs. Celecoxib is a well-known selective COX-2 inhibitor that is in clinical use. In this work, it is demonstrated that celecoxib is also a highly potent direct 5-LO inhibitor. Celecoxib is used in arthritis and its gastro-intestinal side effects are reduced compared to non-selective NSAIDs. In patients with a familiar disposition to polyp forming, celecoxib reduced polyps and the incidence of colon cancer. Because of lowered leukotriene levels in patients under celecoxib therapy it was plausible to test whether celecoxib interferes with 5-LO. Here it is shown that the activity of 5-LO is inhibited in PMNL and cell-free assays with IC50 of 8 microM in intact cells, 20 microM with supplemented arachidonic acid and 30 microM in cell-free systems. Thus, celecoxib is a dual inhibitor of COX-2 and 5-LO. Since 2006, celecoxib has been approved as an orphan drug for the treatment of familial adenomatous polyposis. Aside from this indication, it could be useful for treatment of asthma and other diseases where 5-LO is implicated.
A graph theoretical approach to the analysis, comparison, and enumeration of crystal structures
(2008)
As an alternative approach to lattices and space groups, this work explores graph theory as a means to model crystal structures. The approach uses quotient graphs and nets - the graph theoretical equivalent of cells and lattices - to represent crystal structures. After a short review of related work, new classes of cycles in nets are introduced and their ability to distinguish between non-isomorphic nets and their computational complexity are evaluated. Then, two methods to estimate a structure’s density from the corresponding net are proposed. The first uses coordination sequences to estimate the number of nodes in a sphere, whereas the second method determines the maximal volume of a unit cell. Based on the quotient graph only, methods are proposed to determine whether nets consist of islands, chains, planes, or penetrating, disconnected sub-nets. An algorithm for the enumeration of crystal structures is revised and extended to a search for structures possessing certain properties. Particular attention is given to the exclusion of redundant nets and those, which, by the nature of their connectivity, cannot correspond to a crystal structure. Nets with four four-coordinated nodes, corresponding to sp3 hybridised carbon polymorphs with four atoms per unit cell, are completely enumerated in order to demonstrate the approach. In order to render quotient graphs and nets independent from crystal structures, they are reintroduced in a purely graph-theoretical way. Based on this, the issue of iso- and automorphism of nets is reexamined. It is shown that the topology of a net (that is the bonds in a crystal) constrains severely the symmetry of the embedding (that is the crystal), and in the case of connected nets the space group except for the setting. Several examples are studied and conclusions on phases are drawn (pseudo-cubic FeS2 versus pyrite; α- versus β- quartz; marcasite- versus rutile-like phases). As the automorphisms of certain quotient graphs stipulate a translational symmetry higher than an arbitrary embedding of the corresponding net would show, they are examined in more detail and a method to reduce the size of such quotient graphs is proposed. Besides two instructional examples with 2-dimensional graphs, the halite, calcite, magnesite, barytocalcite, and a strontium feldspar structures are discussed. For some of the structures it is shown that the quotient graph which is equivalent to a centred cell is reduced to a quotient graph equivalent to the primitive cell. For the partially disordered strontium feldspar, it is shown that even if it could be annealed to an ordered structure, the unit cell would likely remain unchanged. For the calcite and barytocalcite structures it is shown that the equivalent nets are not isomorphic.
In this work data of the NA49 experiment at CERN SPS on the energy dependence of multiplicity fluctuations in central Pb+Pb collisions at 20A, 30A, 40A, 80A and 158A GeV, as well as the system size dependence at 158A GeV, is analysed for positively, negatively and all charged hadrons. Furthermore the rapidity and transverse momentum dependence of multiplicity fluctuations are studied. The experimental results are compared to predictions of statistical hadron-gas and string-hadronic models. It is expected that multiplicity fluctuations are sensitive to the phase transition to quark-gluon-plasma (QGP) and to the critical point of strongly interacting matter. It is predicted that both the onset of deconfinement, the lowest energy where QGP is created, and the critical point are located in the SPS energy range. Furthermore, the predictions for the multiplicity fluctuations of statistical and string-hadronic models are different, the experimental data might allow to distinguish between them. The used measure of multiplicity fluctuations is the scaled variance omega, defined as the ratio of the variance and the mean of the multiplicity distribution. In the NA49 experiment the tracks of charged particles are detected in four large volume time projection chambers (TPCs). In order to remove possible detector effects a detailed study of event and track selection criteria is performed. Naively one would expect Poisson fluctuations in central heavy ion collisions. A suppression of fluctuations compared to a Poisson distribution is observed for positively and negatively charged hadrons at forward rapidity in Pb+Pb collisions. At midrapidity and for all charged hadrons the fluctuations are larger than the Poisson ones. The fluctuations seem to increase with decreasing system size. It is suggested that this is due to increased relative fluctuations in the number of participants. Furthermore, it was discovered that omega increases for decreasing rapidity and transverse momentum. A hadron-gas model predicts different values of omega for different statistical ensembles. In the grand-canonical ensemble, where all conservation laws are fulfilled only on the average, not on an event-by-event basis, the predicted fluctuations are the largest ones. In the canonical ensemble the charges, namely the electrical charge, the baryon number and the strangeness, are conserved for each event. The scaled variance in this ensemble is smaller than for the grand-canonical ensemble. In the micro-canonical ensemble not only the charges, but also the energy and the momentum are conserved in each event, the predicted $omega$ is the smallest one. The grand-canonical and canonical formulations of the hadron-gas model over-predict fluctuations in the forward acceptance. In contrast to the experimental data no dependence of omega on rapidity and transverse momentum is expected. For the micro-canonical formulation, which predicts small fluctuations in the total phase space, no quantitative calculation is available yet for the limited experimental acceptance. The increase of fluctuations for low rapidities and transverse momenta can be qualitatively understood in a micro-canonical ensemble as an effect of energy and momentum conservation. The string-hadronic model UrQMD significantly over-predicts the mean multiplicities but approximately reproduces the scaled variance of the multiplicity distributions at all measured collision energies, systems and phase-space intervals. String-hadronic models predict for Pb+Pb collisions a monotonous increase of omega with collision energy, similar to the observations for p+p interactions. This is in contrast to the predictions of the hadron-gas model, where omega shows no energy dependence at higher energies. At SPS energies the predictions of the string-hadronic and hadron-gas models are in the same order of magnitude, but at RHIC and LHC energies the difference in omega in the full phase space is much larger. Experimental data should be able to distinguish between them rather easily. Narrower than Poissonian (omega < 1) multiplicity fluctuations measured in the forward kinematic region (1<y(pi)<y_{beam}) can be related to the reduced fluctuations predicted for relativistic gases with imposed conservation laws. This general feature of relativistic gases may be preserved also for some non-equilibrium systems as modeled by the string-hadronic approaches. A quantitative estimate shows that the predicted maximum in fluctuations due to a first order phase transition from hadron-gas to QGP is smaller than the experimental errors of the present experiment and can therefore neither be confirmed nor disproved. No sign of increased fluctuations as expected for a freeze-out near the critical point of strongly interacting matter is observed.
In the first part of this study, we have identified the two steroid hormones progesterone and norgestimate as novel TRPC channel blockers. Both substances blocked TRPC-mediated Ca2+ influx with micromolar activities in fluorometric measurements. TRPC channel inhibition did not seem to be a general steroid effect since another progestin, the norgestimate metabolite levonorgestrel, was not effective. Norgestimate was 4- to 5-fold more active on the TRPC3/6/7 subfamily compared to TRPC4/5, whereas progesterone was similarly potent. This selectivity of norgestimate was confirmed by patch clamp recordings. As norgestimate blocked channels directly gated by DAG with a fast kinetic, we assume the compound acts on the channel protein itself. This view was further substantiated by the lack of effects on IP3R-mediated Ca2+ release from the endoplasmic reticulum, which is activated in parallel with TRPCs by Gq/11-coupled receptor stimulation. Norgestimate did not only block ectopically expressed TRPC channels but also native, TRPC-mediated currents in rat aortic smooth muscle cells with similar activity. The usefulness of norgestimate as a tool compound for the investigation of physiological TRPC functions was tested in isolated vessel rings. Consistent with TRPC6 being an essential component of the alpha-1-adrenoceptor-activated cation channel, we demonstrated a direct vasorelaxant, endothelium-independent effect of norgestimate on rat aortic rings precontracted with phenylephrine. Thus, our results provide further experimental support for a role of TRPC6 in alpha-1-adrenergic vessel constriction. In the second part of this study, we screened a human aorta cDNA-library for novel TRPC4-interacting proteins with a modified yeast two-hybrid (Y2H) system in which the TRPC4-C-terminus was expressed as tetrameric bait protein, thereby mimicking the native channel conformation. Of the eleven interacting proteins found SESTD1 was chosen for further analyses since it contains a phospholipid-binding Sec14p-like domain and thus could be involved in regulation of TRPC channels by phospholipids. After the biochemical validation of the found interaction, the first spectrin domain of SESTD1 was then identified to interact with the CIRB domain of TRPC4 in directed Y2H tests. SESTD1 also co-immunoprecipitated with the closely related TRPC5 protein in which the SESTD1-binding domain is highly conserved. Independent of the CIRB site, co-immunoprecipitation with TRPC6 and the distantly related TRPM8 channel was observed indicating the existence of other sites in these channel proteins that mediate interaction with SESTD1. Analysis of SESTD1 gene expression in human tissues showed that its transcripts are ubiquitously expressed and tissues with significant coexpression with TRPC4 and -5 were identified. We have generated two polyclonal antisera directed against SESTD1 that consistently detected SESTD1 protein in brain, aorta, heart, and in smooth muscle and endothelial cells. The functional consequences of the found interaction were investigated by examination of the TRPC5-mediated Ca2+ influx in a clonal HM1 cell line stably expressing the channel. Since SESTD1 overexpression had no detectable effects on TRPC5-mediated Ca2+ influx, most likely due to expression of endogenous SESTD1, we knocked-down the native protein with specific siRNA. This procedure reduced TRPC5-mediated Ca2+ influx following receptor stimulation by 50%. Parallel biotinylation experiments did not reveal any differences in cell surface expressed TRPC5-protein, suggesting that reduction of TRPC5 activity resulted from a loss of a direct SESTD1 effect on the channel. In addition, in immunofluorescence experiments we observed that reduced SESTD1 protein levels resulted in a redistribution of the multifunctional protein ß-catenin from the plasma membrane to the cytosol. This result may point to an involvement of SESTD1 in formation and maintenance of adherens junctions. SESTD1 contains a phospholipid-binding Sec14p-like domain and we were the first to demonstrate its Ca2+-dependent binding to phosphatidic acid and all physiological phosphatidylinositol mono- and bisphosphates in vitro. The physiological function of this binding activity is not known at present, but it could play a role in regulation of associated TRPC channels. TRPC4 and -5 channels are activated by phospholipid hydrolysis and also bind phospholipids directly. The identification of SESTD1 as novel TRPC-interacting protein could thus be an important step forward in the investigation and better comprehension of the complex molecular mechanisms of TRP channel regulation by lipids.
Writing against the odds : the south’s cultural and literary struggle against progress and modernity
(2008)
Die Literatur und Kultur der Südstaaten ist entscheidend geprägt von ihrer Orientierung an der eigenen Geschichte und Vergangenheit. Die düstere Vergangenheit, die die Gegenwart überschatten und die Zukunft determiniert ist ein Südstaatenthema par exellence und allgegenwärtig in ihrer Kultur und Literatur. Nach dem Bürgerkrieg und der Reconstruction Era ist der Süden kulturell und ökonomisch ausgeblutet, am Boden und isoliert. Nach dem Krieg weitet sich die Kluft zwischen Nord- und Südstaaten immer weiter aus, ein Prozess, der jedoch schon so alt ist wie die Vereinigten Staaten selbst und bereits im beginnenden 18. Jahrhundert seinen Anfang nimmt. Die Isolation ist gleichzeitig gewollt und ungewollt, bewusst und unbewusst. Die Scham des verlorenen Krieges und die Marginalisierung sind die Katalysatoren für die Kultivierung und das Bestreben nach Erhalt der Besonderheiten der Südstaaten, mit ihrer vermeintlich überlegenen Kultur und Moral. Es beginnt die kommerzialisierte, hoch ideologisierte Konstruktion der Geschichte und Identität der Südstaaten, die in alle Lebensbereiche strahlt. Der melancholische Blick in die Vergangenheit als wichtigste Referenz und kulturellen Fluchtpunkt ersetzt den Eintritt in die Moderne und Modernität mit ihrer Schnelllebigkeit, Austauschbarkeit und die Aufgabe der Tradition für eine rasante Gegenwart. Das Individuum der Südstaaten sieht sich statt mit einer Flut an Wahlmöglichkeiten und Optionen, mit einer einengenden Gesellschaft konfrontiert, die wenig Spielraum für Abweichungen übriglässt und ein harsches Kontrollsystem hat. Es ist eine einzigartige Mischung aus Stolz, Scham und einem Gefühl der gleichzeitigen Unter- und Überlegenheit, die einen besonders guten literarischen Nährboden hervorbringt. In dieser Arbeit wird den historischen, kulturellen, und literarischen Wurzeln der Südstaatenliteratur seit der Southern Renaissance nachgegegangen, um dann die ständig perpetuierten formalen und inhaltlichen Strukturen darzustellen, die wenig Veränderungen erfahren haben. Diese Perpetuierung resultiert aus der einzigartigen Situation der Südstaaten, aus der historischen Last, die unvermindert aktuell bleibt und längst nicht verarbeitet ist. Südstaatenautoren konnten und können nicht die traditionellen Formen und Themen ablegen, solange diese konstituierende Bestandteile der Kultur und Identität der Südstaaten bleiben. Die Südstaaten verweigern sich der Modernität und empfinden Fortschritt und die moderne Massengesellschaft nicht nur als Bedrohung, sondern als Einfluss aus den Nordstaaten, der die eigene Kultur bedroht und eine Einmischung von außen ist, die es abzuwenden gilt. Traditionsbewusste, reaktionäre Tendenzen und Elemente ziehen sich selbst durch vermeintlich progressive, moderne Entwicklungen und Phänomene. Ich kombiniere identitätskonstituierende, isolierende und melancholische Elemente und beleuchte sie historisch, kulturell und literarisch, um eine mehrschichtige Perspektive zu erlangen. Das Verständnis dieser historischen Last und deren unverminderte Bedeutung und Auswirkung auf die Literatur und Kultur der Südstaaten ist essentiell für eine tiefere Einsicht in deren Strukturen und Bedeutung.
The German Working Group on Vegetation Databanks has held annual meetings since 2002 with financial support by the German Federal Agency for Nature Conservation. Ca. 215 members are regularly informed through a mailing-list. The 2008 meeting was hosted by University of Oldenburg’s Landscape Ecology Group and was attended by 72 participants from 15 countries. Software demonstrations of vegetation databanks Turboveg and VegetWeb as well as plant trait databanks LEDA and BiolFlor opened the workshop. There were lecture sessions on trait databanks, recalibration of ecological indicator values and new developments in the field of vegetation databanks. Working groups were devoted to an initiative to build a meta-databank of existing vegetation databanks in Germany and to mathematical modelling of species habitats. In 2009 the 8th workshop will be held on "Vegetation Databanks and Biodindication" at the University of Greifswald.
Naturalness is one of the most important criteria in nature conservation. This paper examines the fundamental concepts underlying the definition and assessment of naturalness. Its role in nature conservation and forest management under conditions of global change is also discussed. The degree of naturalness may be defined in ordinal classes. The “static” concept of the potential natural vegetation (pnV), developed in the 1950ies, is mostly used as the reference state. In other cases, its reversed concept, the hemeroby (degree of articifiality) is assessed, based on the intensity and frequency of human impacts. Since the 1970ies, more attention has been given to natural dynamics than in earlier approaches, e.g. in forest succession models. At the end of the 1980ies, the previous importance was increasingly stressed of natural browsing by large herbivores and the role of predators. These large herbivors are extinct today in most cultural European landscapes. It is assumed, that they open up the canopy, and create park-like forest structures which contain a diversity of habitats for other types of organism (birds, insects). Changed and permanently changing environments and altering patterns of competition between species continue to modify natural processes today. Some of the more conspicuous effects are the extinction of native species and immigration of species to new regions. Long-lived ecosystems like forests are however not able to adapt quickly to such changes and may be unable to find a new balance with the environment. Today, such changes occur very rapidly, and are reducing the original naturalness of ecosystems. Because of this, the criterion “naturalness” must be downweighted. Conversely, more importance should be attached to other criteria: particularly originality (= original naturalness) and restorability. Forestry is contributing to this accelerated change of biocoenoses by increasing disturbances and introducing exotic tree species. Naturalisation of some exotic tree species modifies the natural processes and creates a “new allochthonous naturalness”. Because of this, forest planning should try to preserve or restore stands with attributes of the “original forest”. Exotic species should not be planted, or only in a very restricted way.
Objectives To examine the dose-response relationship between cumulative exposure to kneeling and squatting as well as to lifting and carrying of loads and symptomatic knee osteoarthritis (OA) in a population-based case-control study. Methods In five orthopedic clinics and five practices we recruited 295 male patients aged 25 to 70 with radiographically confirmed knee osteoarthritis associated with chronic complaints. A total of 327 male control subjects were recruited. Data were gathered in a structured personal interview. To calculate cumulative exposure, the self-reported duration of kneeling and squatting as well as the duration of lifting and carrying of loads were summed up over the entire working life. Results The results of our study support a dose-response relationship between kneeling/squatting and symptomatic knee osteoarthritis. For a cumulative exposure to kneeling and squatting > 10.800 hours, the risk of having radiographically confirmed knee osteoarthritis as measured by the odds ratio (adjusted for age, region, weight, jogging/athletics, and lifting or carrying of loads) is 2.4 (95% CI 1.1-5.0) compared to unexposed subjects. Lifting and carrying of loads is significantly associated with knee osteoarthritis independent of kneeling or similar activities. Conclusions As the knee osteoarthritis risk is strongly elevated in occupations that involve both kneeling/squatting and heavy lifting/carrying, preventive efforts should particularly focus on these "high-risk occupations".
The moderate halophile Halobacillus halophilus is the paradigm for chloride dependent growth in prokaryotes. Recent experiments shed light on the molecular basis of the chloride dependence that is reviewed here. In the presence of moderate salinities Halobacillus halophilus mainly accumulates glutamine and glutamate to adjust turgor. The transcription of glnA2 (encoding a glutamine synthetase) as well as the glutamine synthetase activity were identified as chloride dependent steps. Halobacillus halophilus switches its osmolyte strategy and produces proline as the main compatible solute at high salinities. Furthermore, Halobacillus halophilus also shifts its osmolyte strategy at the transition from the exponential to the stationary phase where proline is exchanged by ectoine. Glutamate was found as a second messenger" essential for proline production. This observation leads to a new model of sensing salinity by sensing the physico-chemical properties of different anions.
Increasingly, individuals are in charge of their own financial security and are confronted with ever more complex financial instruments. However, there is evidence that many individuals are not well-equipped to make sound saving decisions. This paper demonstrates widespread financial illiteracy among the U.S. population, particularly among specific demographic groups. Those with low education, women, African-Americans, and Hispanics display particularly low levels of literacy. Financial literacy impacts financial decision-making. Failure to plan for retirement, lack of participation in the stock market, and poor borrowing behavior can all be linked to ignorance of basic financial concepts. While financial education programs can result in improved saving behavior and financial decision-making, much can be done to improve these programs’ effectiveness.
Traditionally, aggregate liquidity shocks are modelled as exogenous events. Extending our previous work (Cao & Illing, 2007), this paper analyses the adequate policy response to endogenous systemic liquidity risk. We analyse the feedback between lender of last resort policy and incentives of private banks, determining the aggregate amount of liquidity available. We show that imposing minimum liquidity standards for banks ex ante are a crucial requirement for sensible lender of last resort policy. In addition, we analyse the impact of equity requirements and narrow banking, in the sense that banks are required to hold sufficient liquid funds so as to pay out in all contingencies. We show that such a policy is strictly inferior to imposing minimum liquidity standards ex ante combined with lender of last resort policy.
Modern macroeconomics empirically addresses economy-wide incentives behind economic actions by using insights from the way a single representative household would behave. This analytical approach requires that incentives of the poor and the rich are strictly aligned. In empirical analysis a challenging complication is that consumer and income data are typically available at the household level, and individuals living in multimember households have the potential to share goods within the household. The analytical approach of modern macroeconomics would require that intra-household sharing is also strictly aligned across the rich and the poor. Here we have designed a survey method that allows the testing of this stringent property of intra-household sharing and find that it holds: once expenditures for basic needs are subtracted from disposable household income, household-size economies implied by the remainder household incomes are the same for the rich and the poor.
Antibiotic resistance of pathogenic bacteria is a major worldwide problem. Bacteria can resist antibiotics by active efflux due to multidrug efflux pumps. The focus of this study has been the mycobacterial multidrug transporter TBsmr because it belongs to the small multidrug resistance (SMR) family whose members are a paradigm to study multidrug efflux due to their small size. SMR proteins are typically 11-12 kDa in size and have a four-transmembrane helix topology. They bind cationic, lipophilic antibiotics such as ethidium bromide (EtBr) and TPP+, and transport them across the membrane in exchange for protons. To understand the molecular mechanism of multidrug resistance, we have to gain information about the structure and function of these proteins. The research described in this thesis aimed to deduce details about the topology, transport cycle and key residues of TBsmr using biophysical techniques. Solid-state NMR (ssNMR) can provide detailed insight into structural organization and dynamical properties of these systems. However, a major bottleneck is the preparation of mg amounts of isotope labeled protein. In case of proteoliposomes, the problem is compounded by the presence of lipids which have to fit into the small active volume of the ssNMR rotor. In Chapter 3, an enhanced protein preparation is described which yields large amounts of TBsmr reconstituted in a native lipid environment suitable for further functional and structual studies. The achieved high protein-to-lipid ratios made a further characterization by ssNMR feasible. The transport activity and oligomeric state of the reconstituted protein in different types of lipid was studied as shown in Chapter 4. The exact oligomeric state of native SMR proteins is still uncertain but a number of biochemical and biophysical studies in detergent suggest that the minimal functional unit capable of binding substrate is a dimer. However, binding assays are not ideal since a protein may bind substrate without completing the transport cycle which can only be shown for reconstituted protein in transport assays.By combining functional data of a TPP+ transport assay with information about theoligomeric state of reconstituted TBsmr obtained by freeze-fracture electron microscopy, it could be shown that lipids affect the function and the oligomeric state of the protein, and that the TBsmr dimer is the minimal functional unit necessary for transport. The transport cycle must involve various conformational states of the protein needed for substrate binding, translocation and release. A fluorescent substrate will therefore experience a significant change of environment while being transported, which influences its fluorescence properties. Thus the substrate itself can report intermediate states that form during the transport cycle. In Chapter 5, the existence of such a substrate-transporter complex for the TBsmr and its substrate EtBr could be shown. The pH gradient needed for antiport has been generated by co-reconstituting TBsmr with bacteriorhodopsin. The measurements have shown the formation of a pH-dependant, transient substrate-protein complex between binding and release of EtBr. This state was further characterized by determining the Kd, by inhibiting EtBr transport through titration with non-fluorescent substrate and by fluorescence anisotropy measurements. The findings support a model with a single occluded intermediate state in which the substrate is highly immobile. Liquid-state NMR is a useful tool to monitor protein-ligand interactions by chemical shift mapping and thus identify and characterize important residues in the protein which are involved in substrate binding. In agreement with previous studies (Krueger-Koplin et al., 2004), the detergent LPPG was found to be highly suitable for liquid-state NMR studies of the membrane protein TBsmr and 42% of the residues could be assigned, as reported in Chapter 6. However, no specific interactions with EtBr were found. This observation was confirmed by LILBID mass spectrometry which showed that TBsmr was predominantly in the non-functional monomeric state. Functional protein was prepared in proteoliposomes which can be investigated by solidstate NMR (Chapter 7). Besides the essential E13, the aromatic residues W63, Y40, and Y60 have been shown to be directly involved in drug binding and transport. Different isotope labeling strategies were evaluated to improve the quality of the NMR spectra to identify and characterize these key residues. In a single tryptophan mutant of reconstituted TBsmr W30A, the binding of ethidium bromide could be detected by 13C solid-state NMR. The measurements have revealed two populations of the conserved W63 residue with distinct backbone structures in the presence of substrate. There is a controversy about the parallel or anti-parallel arrangement of the protomers in the EmrE dimer (Schuldiner, 2007) but this structural asymmetry is consistent with both a parallel and anti-parallel topology.
After the pioneering German “Aktiengesetz” of 1965 and the Brazilian “Lei das Sociedades Anónimas” of 1976, Portugal has become the third country in the world to enact a specific regulation on groups of companies. The Code of Commercial Companies (“Código das Sociedades Comerciais”, abbreviately hereinafter CSC), enacted in 1986, contains a unitary set of rules regulating the relationships between companies, in general, and the groups of companies, in particular (arts. 481° to 508°-E CSC). With this set of rules, the Portuguese legislator has dealt with one of the major topics of modern Company Law. While this branch of law is traditionally conceived as the law of the individual company, modern economic reality is characterized by the massive emergence of large-scale enterprise networks, where parts of a whole business are allocated and insulated in several legally independent companies submitted to an unified economic direction. As Tom HADDEN put it: “Company lawyers still write and talk as if the single independent company, with its shareholders, directors and employees, was the norm. In reality, the individual company ceased to be the most significant form of organization in the 1920s and 1930s. The commercial world is now dominated both nationally and internationally by complex groups of companies”. This trend, which is now observable in any of the largest economies in the world, holds also true for small markets such as Portugal. Although Portuguese economy is still dominated by small and medium-sized enterprises, the organizational structure of the group has always been extremely common. During the 70s, it was estimated that the seven largest groups of companies owned about 50% of the equity capital of all domestic enterprises and were alone responsible for 3/4 of the internal national product. Such a trend has continued and even highlighted in the next decades, surviving to different political and economic scenarios: during the 80s, due to the process of state nationalization of these groups, an enormous public group with more than one thousand controlled companies has been created (“IPE - Instituto de Participações do Estado”); and during the 90s until today, thanks to the reprivatisation movement and the opening of our national market, we assisted to the re-emergence of some large private groups, composed of several hundred subsidiaries each, some of which are listed in foreign stock exchange markets (e.g., in the banking sector, “BCP – Banco Comercial Português”, in the industrial area, “SONAE”, and in the media and communication area, “Portugal-Telecom”).
Reform of the securities class action is once again the subject of national debate. The impetus for this debate is the reports of three different groups – The Committee on Capital Market Regulation, The Commission on the Regulation of U.S. Capital Markets In the 21st Century, and McKinsey & Company. Each of the reports focuses on a single theme: how the contemporary regulatory culture places U.S. capital markets at a competitive disadvantage to foreign markets. While multiple regulatory forces are targeted by each report’s call for reform, each of the reports singles out securities class actions as one of the prime villains that place U.S. capital markets at a competitive disadvantage. The reports’ recommendations range from insignificant changes to drastic curtailments of private class actions. Surprisingly, these current-day cries echo calls for reform heeded by Congress in the not too distant past. Major reform of the securities class action occurred with the Private Securities Litigation Reform Act of 1995.5 Among the PSLRA’s contributions is the introduction of procedures by which the court chooses from among competing petitioners a lead plaintiff for the class. The statute commands that the petitioner with the largest financial loss suffered as a consequence of the defendant’s alleged misrepresentation is presumed to be the most adequate plaintiff. Thus, the lead plaintiff provision supplants the traditional “first to file” rule for selecting the suit’s plaintiff with a mechanism that seeks to harness to the plaintiff’s economic self interest to the suits’ prosecution. Also, by eliminating the race to be the first to file, the lead plaintiff provision seeks to avoid “hair trigger” filings by overly eager plaintiffs’ counsel which Congress believed too frequently gave rise to incomplete and insubstantially pled causes of action. The PSLRA also introduced for securities class actions a heightened pleading requirement8 as well as a bar to the plaintiff obtaining any discovery prior to the district court disposing of the defendants’ motions to dismiss. By introducing the requirement that allegations involving fraud must be plead not only with particularity, but also that the pled facts must establish a “strong inference” of fraud, the PSLRA cast aside, albeit only for securities actions, the much lower notice pleading requirement that has been a fixture of American civil procedure for decades. Substantive changes to the law were also introduced by the PSLRA. With few exceptions, joint and several liability was replaced by proportionate liability so that a particular defendant’s liability is capped by that defendant’s relative degree of fault. Similarly, contribution rights among co-violators are also based on proportionate fault of each defendant. Three years after the PSLRA, Congress returned to the topic again by enacting the Securities Litigation Uniform Standards Act;13 this provision was prompted by aggressive efforts of plaintiff lawyers to bypass the limitations, most notably the bar to discovery and higher pleading requirement, of the PSLRA by bringing suit in state court. Post-SLUSA, securities fraud class actions are exclusively the domain of the federal court. In this paper, we examine the impact of the PSLRA and more particularly the impact the type of lead plaintiff on the size of settlements in securities fraud class actions. We thus provide insight into whether the type of plaintiff that heads the class action impacts the overall outcome of the case. Furthermore, we explore possible indicia that may explain why some suits settle for extremely small sums – small relative to the “provable losses” suffered by the class, small relative to the asset size of the defendantcompany, and small relative to other settlements in our sample. This evidence bears heavily on the debate over “strike suits.” Part I of this paper sets forth the contemporary debate surrounding the need for further reforms of securities class actions. In this section, we set forth the insights advanced in three prominent reports focused on the competitiveness of U.S. capital markets. In Part II we first provide descriptive statistics of our extensive data set, and thenuse multivariate regression analysis to explore the underlying relationships. In Part III, we closely examine small settlements for clues to whether they reflect evidence of strike suits. We conclude in Part IV with a set of policy recommendations based on our analysis of the data. Our goals in this paper are more modest than the Committee Report, the Chamber Report and the McKinsey Report, each of which called for wide-ranging reforms: we focus on how the PSLRA changed securities fraud settlements so as to determine whether the reforms it introduced accomplished at least some of the Act’s important goals. If the PSLRA was successful, and we think it was, then one must be somewhat skeptical of the need for further cutbacks in private securities class action so soon after the Act was passed.
The market reaction to legal shocks and their antidotes : lessons from the sovereign debt market
(2008)
This Article examines the market reaction to a series of legal events concerning the judicial interpretation of the pari passu clause in sovereign debt instruments. More generally, the Article provides insights into the reactions of investors (predominantly financial institutions), issuers (sovereigns), and those who draft bond covenants (lawyers), to unanticipated changes in the judicial interpretation of certain covenant terms.
How do fiscal and technology shocks affect real exchange rates? : New evidence for the United States
(2008)
Using vector autoregressions on U.S. time series relative to an aggregate of industrialized countries, this paper provides new evidence on the dynamic effects of government spending and technology shocks on the real exchange rate and the terms of trade. To achieve identification, we derive robust restrictions on the sign of several impulse responses from a two-country general equilibrium model. We find that both the real exchange rate and the terms of trade – whose responses are left unrestricted – depreciate in response to expansionary government spending shocks and appreciate in response to positive technology shocks.
Motivated by the prominent role of electronic limit order book (LOB) markets in today’s stock market environment, this paper provides the basis for understanding, reconstructing and adopting Hollifield, Miller, Sandas, and Slive’s (2006) (henceforth HMSS) methodology for estimating the gains from trade to the Xetra LOB market at the Frankfurt Stock Exchange (FSE) in order to evaluate its performance in this respect. Therefore this paper looks deeply into HMSS’s base model and provides a structured recipe for the planned implementation with Xetra LOB data. The contribution of this paper lies in the modification of HMSS’s methodology with respect to the particularities of the Xetra trading system that are not yet considered in HMSS’s base model. The necessary modifications, as expressed in terms of empirical caveats, are substantial to derive unbiased market efficiency measures for Xetra in the end.
We explore the pattern of elderly homeownership using microeconomic surveys of 15 OECD countries, merging 60 national household surveys on about 300,000 individuals. In all countries the survey is repeated over time, permitting construction of an international dataset of repeated cross-sectional data. We find that ownership rates decline considerably after age 60 in all countries. However, a large part of the decline depends on cohort effects. Adjusting for them, we find that ownership rates start falling after age 70 and reach a percentage point per year decline after age 75. We find that differences across country ownership trajectories are correlated with indicators measuring the degree of market regulations.
This paper introduces adaptive learning and endogenous indexation in the New-Keynesian Phillips curve and studies disinflation under inflation targeting policies. The analysis is motivated by the disinflation performance of many inflation-targeting countries, in particular the gradual Chilean disinflation with temporary annual targets. At the start of the disinflation episode price-setting firms’ expect inflation to be highly persistent and opt for backward-looking indexation. As the central bank acts to bring inflation under control, price-setting firms revise their estimates of the degree of persistence. Such adaptive learning lowers the cost of disinflation. This reduction can be exploited by a gradual approach to disinflation. Firms that choose the rate for indexation also re-assess the likelihood that announced inflation targets determine steady-state inflation and adjust indexation of contracts accordingly. A strategy of announcing and pursuing short-term targets for inflation is found to influence the likelihood that firms switch from backward-looking indexation to the central bank’s targets. As firms abandon backward-looking indexation the costs of disinflation decline further. We show that an inflation targeting strategy that employs temporary targets can benefit from lower disinflation costs due to the reduction in backward-looking indexation.
Monetary policy analysts often rely on rules-of-thumb, such as the Taylor rule, to describe historical monetary policy decisions and to compare current policy to historical norms. Analysis along these lines also permits evaluation of episodes where policy may have deviated from a simple rule and examination of the reasons behind such deviations. One interesting question is whether such rules-of-thumb should draw on policymakers "forecasts of key variables such as inflation and unemployment or on observed outcomes. Importantly, deviations of the policy from the prescriptions of a Taylor rule that relies on outcomes may be due to systematic responses to information captured in policymakers" own projections. We investigate this proposition in the context of FOMC policy decisions over the past 20 years using publicly available FOMC projections from the biannual monetary policy reports to the Congress (Humphrey-Hawkins reports). Our results indicate that FOMC decisions can indeed be predominantly explained in terms of the FOMC´s own projections rather than observed outcomes. Thus, a forecast-based rule-of-thumb better characterizes FOMC decision-making. We also confirm that many of the apparent deviations of the federal funds rate from an outcome-based Taylor-style rule may be considered systematic responses to information contained in FOMC projections.
Risk transfer with CDOs
(2008)
Modern bank management comprises both classical lending business and transfer of asset risk to capital markets through securitization. Sound knowledge of the risks involved in securitization transactions is a prerequisite for solid risk management. This paper aims to resolve a part of the opaqueness surrounding credit-risk allocation to tranches that represent claims of different seniority on a reference portfolio. In particular, this paper analyzes the allocation of credit risk to different tranches of a CDO transaction when the underlying asset returns are driven by a common macro factor and an idiosyncratic component. Junior and senior tranches are found to be nearly orthogonal, motivating a search for the whereabout of systematic risk in CDO transactions. We propose a metric for capturing the allocation of systematic risk to tranches. First, in contrast to a widely-held claim, we show that (extreme) tail risk in standard CDO transactions is held by all tranches. While junior tranches take on all types of systematic risk, senior tranches take on almost no non-tail risk. This is in stark contrast to an untranched bond portfolio of the same rating quality, which on average suffers substantial losses for all realizations of the macro factor. Second, given tranching, a shock to the risk of the underlying asset portfolio (e.g. a rise in asset correlation or in mean portfolio loss) has the strongest impact, in relative terms, on the exposure of senior tranche CDO-investors. Our findings can be used to explain major stylized facts observed in credit markets.
We show that the use of correlations for modeling dependencies may lead to counterintuitive behavior of risk measures, such as Value-at-Risk (VaR) and Expected Short- fall (ES), when the risk of very rare events is assessed via Monte-Carlo techniques. The phenomenon is demonstrated for mixture models adapted from credit risk analysis as well as for common Poisson-shock models used in reliability theory. An obvious implication of this finding pertains to the analysis of operational risk. The alleged incentive suggested by the New Basel Capital Accord (Basel II), amely decreasing minimum capital requirements by allowing for less than perfect correlation, may not necessarily be attainable.
The paper proposes a panel cointegration analysis of the joint development of government expenditures and economic growth in 23 OECD countries. The empirical evidence provides indication of a structural positive correlation between public spending and per-capita GDP which is consistent with the so-called Wagner´s law. A long-run elasticity larger than one suggests a more than proportional increase of government expenditures with respect to economic activity. In addition, according to the spirit of the law, we found that the correlation is usually higher in countries with lower per-capita GDP, suggesting that the catching-up period is characterized by a stronger development of government activities with respect to economies in a more advanced state of development.