The Zethus of Venezuela (Hymenoptera: Eumenidae)
Lionel A. Stange
- Thirty four species of Zethus are enumerated from Venezuela, providing known and new locality records. Six new species are described: Z. rubioi and Z. vincenti in the subgenus Zethusculus, Z. carpenteri and Z. milleri in the subgenus Zethoides, and Z. bolivarensis and Z. yepezi in the nominate subgenus. A key to the species of Venezuela is provided. The distribution patterns of Zethus are discussed.
Further description of Ananthidium Urban, with keys to the Argentine Anthidiini (Hymenoptera: Megachilidae)
Lionel A. Stange
- Additional descriptive information is given for the genus Ananthidium Urban with a key to species. Also, new geographical and floral records are given. A key to the genera of the Anthidiini of Argentina is provided. Bothranthidium Moure is considered a subgenus of Anthodioctes. A brief discussion of generic characters of the South American genera are given. Carlotica Moure & Urban is placed as a synonym of Epanthidium Moure. Also, Saranthidium Moore & Hurd is considered as a subgenus of Hypanthidiodes Moore.
Reclassification of the New World antlion genera formerly included in the tribe Brachynemurini (Neuroptera: Myrmeleontidae)
Lionel A. Stange
- A cladistic analysis of the New World tribe Brachynemurini has resulted in several new taxonomic designations. The tribe is divided into 3 tribes, 2 of which are newly described. The Brachynemurini S.S. now contains 12 genera of which Argentoleon, Atricholeon, Mexoleon and Venezueleon are newly described. The Gnopholeontini (NEW TRIBE) includes 4 North American genera whereas the Lemolemini (NEW TRIBE) contains 6 South American genera of which Ecualeon and Galapagoleon are newly described. Descriptions of genera in the 3 tribes, based on adults and known larvae, are given. Keys to the genera in each tribe are provided, as well as a key to the tribes of Myrmeleontidae.
Secondary organic aerosol formation from photooxidation of naphthalene and alkylnaphthalenes: implications for oxidation of intermediate volatility organic compounds (IVOCs)
Arthur Wing Hong Chan
Kathryn E. Kautzman
Puneet Singh Chhabra
Jason D. Surratt
Man N. Chan
John D. Crounse
Paul O. Wennberg
Richard C. Flagan
John H. Seinfeld
- Current atmospheric models do not include secondary organic aerosol (SOA) production from gas-phase reactions of polycyclic aromatic hydrocarbons (PAHs). Recent studies have shown that primary semivolatile emissions, previously assumed to be inert, undergo oxidation in the gas phase, leading to SOA formation. This opens the possibility that low-volatility gas-phase precursors are a potentially large source of SOA. In this work, SOA formation from gas-phase photooxidation of naphthalene, 1-methylnaphthalene (1-MN), 2-methylnaphthalene (2-MN), and 1,2-dimethylnaphthalene (1,2-DMN) is studied in the Caltech dual 28-m3 chambers. Under high-NOx conditions and aerosol mass loadings between 10 and 40 μg m, the SOA yields (mass of SOA per mass of hydrocarbon reacted) ranged from 0.19 to 0.30 for naphthalene, 0.19 to 0.39 for 1-MN, 0.26 to 0.45 for 2-MN, and constant at 0.31 for 1,2-DMN. Under low-NOx conditions, the SOA yields were measured to be 0.73, 0.68, and 0.58, for naphthalene, 1-MN, and 2-MN, respectively. The SOA was observed to be semivolatile under high-NOx conditions and essentially nonvolatile under low-NOx conditions, owing to the higher fraction of ring-retaining products formed under low-NOx conditions. When applying these measured yields to estimate SOA formation from primary emissions of diesel engines and wood burning, PAHs are estimated to yield 3–5 times more SOA than light aromatic compounds. PAHs can also account for up to 54% of the total SOA from oxidation of diesel emissions, representing a potentially large source of urban SOA.
Saharan dust and ice nuclei over Central Europe
Leonard A. Barrie
- Surface measurements of aerosol and ice nuclei (IN) at a Central European mountain site during an episode of dust transport from the Sahara are presented. Ice nuclei were sampled by electrostatic precipitation on silicon wafers and were analyzed in an isothermal static vapor diffusion chamber. The transport of mineral dust is simulated by the Eulerian regional dust model DREAM. Ice nuclei and mineral dust are significantly correlated, in particular IN number concentration and aerosol surface area. The ice nucleating characteristics of the aerosol as analyzed with respect to temperature and supersaturation are similar during the dust episode than during the course of the year. This suggests that dust may be a main constituent of ice nucleating aerosols in Central Europe.
On the correlation between hydrogen bonding and melting points in the inositols
Sándor L. Bekö
Martin U. Schmidt
Jacco van de Streek
- Inositol, 1,2,3,4,5,6-hexahydroxycyclohexane, exists in nine stereoisomers with different crystal structures and melting points. In a previous paper on the relationship between the melting points of the inositols and the hydrogen-bonding patterns in their crystal structures [Simperler et al. (2006[Simperler, A., Watt, S. W., Bonnet, P. A., Jones, W. & Motherwell, W. D. S. (2006). CrystEngComm, 8, 589-600.]). CrystEngComm 8, 589], it was noted that although all inositol crystal structures known at that time contained 12 hydrogen bonds per molecule, their melting points span a large range of about 170 °C. Our preliminary investigations suggested that the highest melting point must be corrected for the effect of molecular symmetry, and that the three lowest melting points may need to be revised. This prompted a full investigation, with additional experiments on six of the nine inositols. Thirteen new phases were discovered; for all of these their crystal structures were examined. The crystal structures of eight ordered phases could be determined, of which seven were obtained from laboratory X-ray powder diffraction data. Five additional phases turned out to be rotator phases and only their unit cells could be determined. Two previously unknown melting points were measured, as well as most enthalpies of melting. Several previously reported melting points were shown to be solid-to-solid phase transitions or decomposition points. Our experiments have revealed a complex picture of phases, rotator phases and phase transitions, in which a simple correlation between melting points and hydrogen-bonding patterns is not feasible.
CCDC references: 891302; 891303; 891304; 891305; 891307; 891309
The challenge of conserving amphibian megadiversity in Madagascar
Angus I. Carpenter
Louis du Preez
Joseph R. Mendelson III
Russell A. Mittermeier
Robin D. Moore
Nirhy H. C. Rabibisoa
Noromalala Rasoamampionona Raminosoa
Olga Ravoahangimalala Ramilijaona
Christopher J. Raxworthy
David R. Vieites
Adaptor SKAP-55 binds p21ras activating exchange factor RasGRP1 and negatively regulates the p21ras-ERK pathway in T-Cells
Christopher E. Rudd
- 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.
The plasmodium export element revisited
Jan Alexander Hiß
Jude Marek Przyborski
- 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.
The RRM domain of poly(A)-specific ribonuclease has a noncanonical binding site for mRNA cap analog recognition
- 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.