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21.
Axel Garboe 《Genetica》1929,11(6):465-490
Ohne Zusammenfassung 相似文献
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Ylenia Chiari Pablo Orozco-terWengel Miguel Vences David R. Vieites Augustin Sarovy Jasmin E. Randrianirina Axel Meyer Edward Louis Jr. 《Conservation Genetics》2006,7(4):473-482
Dyscophus antongilii and D. guineti are two morphologically very similar microhylid frogs from Madagascar of uncertain taxonomy. D. antongilii is currently included in Appendix I of the Convention on the International Trade in Endangered Species (CITES) and its exportation is banned completely. In contrast, D. guineti does not receive any legal protection and it is regularly exported. Field data on ecology and behaviour are to a large extent lacking. Here we report on a genetic survey of D. antongilii and D. guineti using nuclear and mitochondrial DNA markers. Sequences of a fragment of 501 bp of the mitochondrial cytochrome b gene from one population of D. antongilii and two populations of D. guineti resulted in a single haplotype network, without haplotype sharing among the populations. However, haplotypes of D.␣guineti were only 1–4 mutational steps from those of D. antongilii, and did not form a clade. The analysis of eight microsatellites newly developed and standardized for D. antongilii revealed an excess of homozygotes and the absence of Hardy–Weinberg equilibrium. The microsatellite data clearly distinguished between D. antongilii and D. guineti, and fixed differences were observed at one locus. Although confirmation of the status of Dyscophus antongilii and D. guineti as separate species requires further data, our study supports the definition of these two taxa as different evolutionary significant units under the adaptive evolutionary conservation concept. 相似文献
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Bernadette Schreiner Heike Westerburg Ignasi Forné Axel Imhof Walter Neupert Dejana Mokranjac 《Molecular biology of the cell》2012,23(22):4335-4346
The vast majority of mitochondrial proteins are synthesized in the cytosol and transported into the organelle in a largely, if not completely, unfolded state. The proper function of mitochondria thus depends on folding of several hundreds of proteins in the various subcompartments of the organelle. Whereas folding of proteins in the mitochondrial matrix is supported by members of several chaperone families, very little is known about folding of proteins in the intermembrane space (IMS). We targeted dihydrofolate reductase (DHFR) as a model substrate to the IMS of yeast mitochondria and analyzed its folding. DHFR can fold in this compartment, and its aggregation upon heat shock can be prevented in an ATP-dependent manner. Yme1, an AAA (ATPases associated with diverse cellular activities) protease of the IMS, prevented aggregation of DHFR. Analysis of protein aggregates in mitochondria lacking Yme1 revealed the presence of a number of proteins involved in the establishment of mitochondrial ultrastructure, lipid metabolism, protein import, and respiratory growth. These findings explain the pleiotropic effects of deletion of YME1 and suggest an important role for Yme1 as a folding assistant, in addition to its proteolytic function, in the protein homeostasis of mitochondria 相似文献
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Limestone-marl alternations represent a common type of fine-grained calcareous rhythmites during the entire Phanerozoic. Their diagenetic overprint, however, obliterates their value for palaeoenvironmental interpretations. The original mineralogical composition of the carbonate fraction (aragonite, high-Mg calcite, low-Mg calcite) would potentially yield important information on palaeoenvironmental conditions: for example shallow-water carbonate factories are usually characterised by extensive aragonite production, whereas pelagic carbonate production is dominated by calcitic organisms. Therefore, a reconstruction of the pre-diagenetic mineralogical composition of limestone-marl precursors would be desirable. A particularly conspicuous attribute of fine-grained calcareous rhythmites is the intercalation of two rock types that have undergone two entirely different diagenetic pathways (“differential diagenesis”). As indicated by earlier petrography work, in the interlayers selective aragonite dissolution has taken place, and the dissolved aragonite provided the cement for the limestones. Primary aragonite usually is not preserved in diagenetically mature fine-grained limestones. However, in a recently published paper a method is proposed to quantify the primary mineralogical composition of the precursor sediments of a fine-grained calcareous rhythmite. Here we apply this method to several published data sets from sections of Cambrian to Jurassic age. We try to answer the following questions: Where does the aragonite come from, especially during times of “calcite seas”? What is the impact of the enhanced pelagic carbonate production since the Late Jurassic on the formation of limestone-marl alternations? How much dissolved aragonite is lost to sea water during early marine burial diagenesis, i.e. how closed is the diagenetic system? As demonstrated for the five examples shown here, the new method for reconstructing primary mineralogy potentially provides insight into ancient depositional environments, surface productivity, and ocean chemistry. 相似文献
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Axel Kleidon 《Biologia》2006,61(19):S234-S239
The terrestrial biosphere shapes the exchange fluxes of energy and mass at the land surface. The diversity of plant form and functioning can potentially result in a wide variety of possible climatic conditions at the land surface and in the soil, which in turn feed back to more or less suitable conditions for terrestrial productivity. Here, I use sensitivity simulations to vegetation form and functioning with a global climate model to quantify this possible range of steady-states (“PROSS”) of the surface energy-and mass balances. The surface energy-and water balances over land are associated with substantial sensitivity to vegetation parameters, with precipitation varying by more than a factor of 2, and evapotranspiration by a factor of 5. This range in biologically possible climatic conditions is associated with drastically different levels of vegetation productivity. Optimum conditions for maximum productivity are close to the simulated climate of present-day conditions. These results suggest the conclusions that (a) climate does not determine vegetation form and function, but merely constrains it, and (b) the emergent climatic conditions at the land surface seem to be close to optimal for the functioning of the terrestrial biosphere. 相似文献
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