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Seit 12 Jahren werden von Mitgliedern der Eurasian Dry Grassland Group (EDGG) und deren Vorgängerorganisationen Grasland-Sonderteile in Tuexenia herausgegeben. Der diesjährige Sonderteil enthält fünf Artikel, die das Grasland verschiedener mitteleuropäischer Länder mit unterschiedlichen Zielen untersuchen. Der erste Artikel untersucht Auswirkungen von Weide und Mahd auf die Diversität des Graslands in Deutschland in Abhängigkeit von verschiedenen Umweltfaktoren, der zweite die Auswirkung kleiner Büsche auf den Artenreichtum von Gefäßpflanzen in beweideten Wiesensteppen in Ungarn. Der dritte Artikel fragt, ob sich ungarische Sandtrockenrasen mit Festuca vaginata von solchen mit F. pseudovaginata in ihrer Vegetation und ihren Standortsbedingungen unterscheiden; die letztere war erst kürzlich beschrieben worden. Der vierte Artikel modelliert Auswirkungen des Klimawandels auf geschützte Graslandbestände in Serbien und deren Arten während schließlich der fünfte Artikel die Initiative einer neuen Datenbank des deutschen Graslands (GrassVeg.DE) vorstellt und dazu aufruft, sich daran zu beteiligen. Insgesamt haben zu diesem 12. Grasland-Sonderteil 41 Autoren aus fünf Ländern (Dänemark, Deutschland, Italien, Schweiz, Serbien und Ungarn) beigetragen.
At the edge of the Harz Mountains in Lower Saxony a population of the hart's tongue fern (Asplenium scolopendrium) threatened by destruction by a gypsum quarry were transplanted into a dolina which was not populated by the species at that time, and the new population was followed over ten years. 90% of the 59 transplanted plants survived this period and grew larger during the first six years after transplantation. Progenies appeared in the third year after transplantation. Nowadays, in the tenth year after transplantation, there are 1110 progenies, 171 of which are reproducing. Overall, the population increased by 1781% in the ten years. Plants that were planted on a rocky slope or a boulder heap in the new habitat, where soil was available, grew better than plants in rock faces without soil. In contrast, in the rock faces, where substrate was not covered with autumn foliage, more juveniles established. The distance between juveniles and mother plants rarely exceeded three meters, which indicates a limited dispersal potential of the hart’s tongue fern and may explain together with low diaspore pressure as a result of local rarity of the species that the dolina had not been colonized spontaneously. We conclude that transplantations of adult plants or introduction of spores are a suitable measure for preserving hart’s tongue fern populations that are endangered by destruction. In the long run, however, such measures cannot compensate for ongoing destruction of natural habitats by mining activities in the gypsum karst region at the southern edge of the Harz Mountains.
Ribosome recycling orchestrated by the ATP binding cassette (ABC) protein ABCE1 can be considered as the final—or the first—step within the cyclic process of protein synthesis, connecting translation termination and mRNA surveillance with re-initiation. An ATP-dependent tweezer-like motion of the nucleotide-binding domains in ABCE1 transfers mechanical energy to the ribosome and tears the ribosome subunits apart. The post-recycling complex (PRC) then re-initiates mRNA translation. Here, we probed the so far unknown architecture of the 1-MDa PRC (40S/30S·ABCE1) by chemical cross-linking and mass spectrometry (XL-MS). Our study reveals ABCE1 bound to the translational factor-binding (GTPase) site with multiple cross-link contacts of the helix–loop–helix motif to the S24e ribosomal protein. Cross-linking of the FeS cluster domain to the ribosomal protein S12 substantiates an extreme lever-arm movement of the FeS cluster domain during ribosome recycling. We were thus able to reconstitute and structurally analyse a key complex in the translational cycle, resembling the link between translation initiation and ribosome recycling.
The endoplasmic reticulum–mitochondria encounter structure (ERMES) connects the mitochondrial outer membrane with the ER. Multiple functions have been linked to ERMES, including maintenance of mitochondrial morphology, protein assembly and phospholipid homeostasis. Since the mitochondrial distribution and morphology protein Mdm10 is present in both ERMES and the mitochondrial sorting and assembly machinery (SAM), it is unknown how the ERMES functions are connected on a molecular level. Here we report that conserved surface areas on opposite sides of the Mdm10 β-barrel interact with SAM and ERMES, respectively. We generated point mutants to separate protein assembly (SAM) from morphology and phospholipid homeostasis (ERMES). Our study reveals that the β-barrel channel of Mdm10 serves different functions. Mdm10 promotes the biogenesis of α-helical and β-barrel proteins at SAM and functions as integral membrane anchor of ERMES, demonstrating that SAM-mediated protein assembly is distinct from ER-mitochondria contact sites.
In the lower siliceous uplands of Central Europe, various types of nutrient-poor grasslands are widespread and grow intermingled. These species-rich grasslands, often dominated by taxa of the Festuca ovina aggregate, comprise various phytosociological classes. They are remnants of a historic rural lands - cape and are of conservation importance. Few studies on such grasslands are available and there has been disagreement in assigning them to appropriate habitat types or syntaxa. We investigated such nutrient-poor grasslands in the lower Aar valley (Middle Hesse, Rhenish Massif). We surveyed 104 vegetation plots distributed throughout the valley and identified syntaxa to (sub)association level. We carried out supervised classification combining cluster analysis, a priori assignment to classes based on prevailing diagnostic species, and regional refinement based on phi-value maximisation of the units. As a result, we classified five associations within four classes: Polytricho piliferi-Festucetum tenuifoliae/Galio harcynici-Deschampsietum flexuosae and Festuco rubrae-Genistelletum sagittalis (Calluno- Ulicetea), Jasiono montanae-Festucetum ovinae (Koelerio-Corynephoretea), Gentiano-Koelerietum pyramidatae (Festuco-Brometea) and Arrhenatheretum elatioris (Molinio-Arrhenatheretea). Ecologically, soil acidity (resulting from Ca concentrations of the bedrock) was the main cause of floristic dissimilarity of the grasslands and thus community differentiation. Many stands grew on soils with intermediate pH and showed a peculiar mixture of basiphilous and acidophilous species. We conclude that (i) our approach of supervised classification yields convincing reproducible results when a syntaxonomic system is adapted top-down to a geographically restricted area, (ii) nutrient-poor siliceous grasslands dominated by taxa of the Festuca ovina aggregate can be well assigned to ecologically meaningful syntaxa, and (iii) the nutrient-poor siliceous grasslands of the Lahn-Dill Highlands are of high conservation relevance and in urgent need of protection.
Molecular analysis of the ribosome recycling factor ABCE1 bound to the 30S post-splitting complex
(2020)
Ribosome recycling by the twin-ATPase ABCE1 is a key regulatory process in mRNA translation and surveillance and in ribosome-associated protein quality control in Eukarya and Archaea. Here, we captured the archaeal 30S ribosome post-splitting complex at 2.8 Å resolution by cryo-electron microscopy. The structure reveals the dynamic behavior of structural motifs unique to ABCE1, which ultimately leads to ribosome splitting. More specifically, we provide molecular details on how conformational rearrangements of the iron–sulfur cluster domain and hinge regions of ABCE1 are linked to closure of its nucleotide-binding sites. The combination of mutational and functional analyses uncovers an intricate allosteric network between the ribosome, regulatory domains of ABCE1, and its two structurally and functionally asymmetric ATP-binding sites. Based on these data, we propose a refined model of how signals from the ribosome are integrated into the ATPase cycle of ABCE1 to orchestrate ribosome recycling.
Introduction: Prophylaxis with factor VIII (FVIII) concentrates in children with haemophilia A (HA) is current standard of care. The benefit of prophylactic treatment for adult HA patients is not commonly accepted.
Aim: To investigate the benefit of prophylaxis over on‐demand treatment in adult and elderly patients with severe or non‐severe HA in a real‐life setting.
Methods: Data from 163 patients comprising 1202 patient‐years were evaluated for 7.5 (±5.3) years. The effects on the annual bleeding rate (ABR, including spontaneous and traumatic bleeds) of treatment with a plasma‐derived FVIII concentrate, the patient's age and disease severity were investigated. The effect of changing the treatment from on demand to continuous prophylaxis on the patients’ ABRs was further analysed.
Results: Prophylaxis had the greatest effect on the ABRs of patients of any age with severe or non‐severe HA. The difference in ABR of all patients treated on demand (median 31.4; interquartile range (IQR) 27.6; N = 83) compared with those treated prophylactically (median 1.3; IQR 3.6; N = 122) was statistically significant (P < .05), even for patients with non‐severe HA (median 8.4; IQR 15.5; N = 11) vs median 1.5; IQR 4.2 (N = 17), P < .05). Patients, aged up to 88 years, switching from on demand to continuous prophylaxis showed the lowest median ABR (1.1; N = 51) after their regimen change.
Conclusion: Any (even low‐frequency) prophylaxis results in lower ABR than on‐demand treatment. Patients switching to prophylaxis benefitted the most, irrespective of age or HA severity. Prophylactic treatment—even tertiary—is the regimen of choice for patients of any age, including elderly patients, with severe or non‐severe HA.
The Transylvanian Plateau in Romania is well known to host large areas of a variety of dry grassland types, still traditionally managed by low-intensity mowing or grazing. While this natural heritage is now under threat from changes in agricultural practices, the diversity of Transylvanian dry grasslands is still little understood. There is a lack of both field data sampled with standardised methods and a syntaxonomic treatment with modern statistical methods and supra-regional perspective. Therefore, the European Dry Grassland Group (EDGG) carried out its first international Research Expedition in Transylvania 2009 to study syntaxonomy, vegetation-environment relationships, and biodiversity patterns of these communities. In various locations across Transylvania, we sampled 10-m² vegetation plots (n = 82) and nested-plot series from 0.0001 m² to 100 m² (n = 20), including all vascular plant, bryophyte, and lichen species, as well as structural and soil data. The vegetation classification was carried out with modified TWINSPAN, followed by determination of diagnostic species with phi values and a small-scale re-assignment of relevés with the aim of crispness maximisation. Both TWINSPAN and ordination revealed three major groups of syntaxa, which were matched to three orders from the class of basiphilous dry grasslands, Festuco-Brometea, represented by one alliance each: rocky dry grasslands (Stipo pulcherrimae-Festucetalia pallentis: Seslerion rigidae); xeric grasslands on deep soils (Festucetalia valesiacae: Stipion lessingianae) and meso-xeric grasslands on deep soils (Brachypodietalia pinnati: Cirsio-Brachypodion pinnati). We accepted nine association-level units plus two that potentially merit association status but were only represented by one relevé each. Most of the units could be identified with one or several previously described associations. To support nomenclatural stability, we provide a nomenclatural revision and designate nomenclatural types where previously there were none. Further, we used DCA ordination and analysis of variance to determine the main environmental drivers of floristic differentiation and to determine ecological and structural differences between the vegetation types. The strongest differentiation occurred along the aridity gradient with the dense, particularly diverse stands on more or less level sites on the one hand (Brachypodietalia pinnati) and the more open, less diverse stands on steep south-facing slopes on the other end of the gradient (Stipo pulcherrimae- Festucetalia pallentis, Festucetalia valesiacae). The two xeric orders were then separated along the second DCA axis, with the Stipo pulcherrimae-Festucetalia pallentis inhabiting the stone-rich sites at higher altitudes while the Festucetalia valesiacae occur on soft, deep substrata at lower altitudes. The analysed dry grassland communities have extraordinarily high -diversity at all spatial scales for all plants and for vascular plants, but are relatively poor in bryophytes and lichens. Some formerly mown stands of the Festuco sulcatae-Brachypodietum pinnati (Brachypodietalia pinnati) are even richer in vascular plant species than any other recorded vegetation type worldwide on the spatial scales of 0.1 m² (43) and 10 m² (98); the respective relevés are documented here for the first time. Also, the b-diversity of the grasslands was unexpectedly high, with a mean z-value of 0.275. Despite its limited extent, the methodological thoroughness of this study allows us to shed new light on the syntaxonomy of dry grasslands in Romania and to raise the awareness that Transylvania still hosts High Nature Value grasslands that are bio - diversity hotspots at a global scale but at the same time are highly endangered through changes in agricultural practices.
Background: Simultaneous pancreas kidney transplantation (SPK), pancreas transplantation alone (PTA) or pancreas transplantation after kidney (PAK) are the only curative treatment options for patients with type 1 (juvenile) diabetes mellitus with or without impaired renal function. Unfortunately, transplant waiting lists for this indication are increasing because the current organ acceptability criteria are restrictive; morbidity and mortality significantly increase with time on the waitlist. Currently, only pancreas organs from donors younger than 50 years of age and with a body mass index (BMI) less than 30 are allocated for transplantation in the Eurotransplant (ET) area. To address this issue we designed a study to increase the available donor pool for these patients.
Methods/Design: This study is a prospective, multicenter (20 German centers), single blinded, non-randomized, two armed trial comparing outcome after SPK, PTA or PAK between organs with the currently allowed donor criteria versus selected organs from donors with extended criteria. Extended donor criteria are defined as organs procured from donors with a BMI of 30 to 34 or a donor age between 50 and 60 years. Immunosuppression is generally standardized using induction therapy with Myfortic, tacrolimus and low dose steroids. In principle, all patients on the waitlist for primary SPK, PTA or PAK are eligible for the clinical trial when they consent to possibly receiving an extended donor criteria organ. Patients receiving an organ meeting the current standard criteria for pancreas allocation (control arm) are compared to those receiving extended criteria organ (study arm); patients are blinded for a follow-up period of one year. The combined primary endpoint is survival of the pancreas allograft and pancreas allograft function after three months, as an early relevant outcome parameter for pancreas transplantation.
Discussion: The EXPAND Study has been initiated to investigate the hypothesis that locally allocated extended criteria organs can be transplanted with similar results compared to the currently allowed standard ET organ allocation. If our study shows a favorable comparison to standard organ allocation criteria, the morbidity and mortality for patients waiting for transplantation could be reduced in the future.
Trial registered at: NCT01384006
In our contribution, we report on the 6th European Dry Grassland Meeting held from 31 August to 1 September 2009 in Halle (Saale), Germany. The meeting was attended by 40 participants, who gave 15 oral and 17 poster presentations. The rapid positive development of the European Dry Grassland Group (EDGG), the organiser of this conference, is mentioned: the inclusion of the EDGG in the International Association for Vegetation Science (IAVS) as a working group, the establishment of two new subgroups focussing on Mediterranean and South-East European dry grasslands, respectively, and the organisation of the first EDGG research expedition in 2010 belong to the most important events. In the last part of our contribution, we give a short introduction to the six articles of this Special Feature. Two of them deal with phytosociological classification of semi-natural grassland communities, one with vegetation- environment relationships. Two papers are concerned with conservational topics, one focussing on the population structure of endangered Pulsatilla patens, the other dealing with conservation of xeric grasslands in Transylvania. The last paper examines temporal changes in calcareous grasslands with regard to species diversity.