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871.
Mark Stettner Jennifer Zenker Fabian Klingler Fabian Szepanowski Hans-P. Hartung Anne K. Mausberg Christoph Kleinschnitz Roman Chrast Bernd C. Kieseier 《Cellular and molecular neurobiology》2018,38(2):487-496
The protein component of the myelin layer is essential for all aspects of peripheral nerves, and its deficiency can lead to structural and functional impairment. The presence of peripheral myelin protein 2 (P2, PMP2, FABP8, M-FABP) in Schwann cells has been known for decades and shown recently to be involved in the lipid homeostasis in the peripheral neural system. However, its precise role during de- and remyelination has yet to be elucidated. To this end, we assessed remyelination after sciatic nerve crush injury in vivo, and in an experimental de/remyelination ex vivo myelinating culture model in P2-deficient (P2 ?/? ) and wild-type (WT) animals. In vivo, the nerve crush paradigm revealed temporal structural and functional changes in P2 ?/? mice as compared to WT animals. Concomitantly, P2 ?/? DRG cultures demonstrated the presence of shorter internodes and enlarged nodes after ex vivo de/remyelination. Together, these data indicate that P2 may play a role in remyelination of the injured peripheral nervous system, presumably by affecting the nodal and internodal configuration. 相似文献
872.
Bärbel Wittel Till Vogel Heiko Scharl Sven Nerdinger Bernd Lehnemann Andreas Meudt Victor Snieckus 《Bioorganic & medicinal chemistry》2018,26(15):4583-4593
The use of two biphenyl sulfonic acid ligands for the catalytic C-N cross coupling of aryl halides with anilines, 3-aminopyridine, and secondary amines is reported. Our results represent a significant improvement compared to state of the art methods especially with regards to the removal of palladium. 相似文献
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Intraspecific trait variation and trade‐offs within and across populations of a toxic dinoflagellate 下载免费PDF全文
Karen M. Brandenburg Sylke Wohlrab Uwe John Anke Kremp Jacqueline Jerney Bernd Krock Dedmer B. Van de Waal 《Ecology letters》2018,21(10):1561-1571
Intraspecific trait diversity can promote the success of a species, as complementarity of functional traits within populations may enhance its competitive success and facilitates resilience to changing environmental conditions. Here, we experimentally determined the variation and relationships between traits in 15 strains of the toxic dinoflagellate Alexandrium ostenfeldii derived from two populations. Measured traits included growth rate, cell size, elemental composition, nitrogen uptake kinetics, toxin production and allelochemical potency. Our results demonstrate substantial variation in all analysed traits both within and across populations, particularly in nitrogen affinity, which was even comparable to interspecific variation across phytoplankton species. We found distinct trade‐offs between maximum nitrogen uptake rate and affinity, and between defensive and competitive traits. Furthermore, we identified differences in trait variation between the genetically similar populations. The observed high trait variation may facilitate development and resilience of harmful algal blooms under dynamic environmental conditions. 相似文献
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Martin Poot Oliver Groß Bernd Epe Michael Pflaum Holger Hoehn 《Experimental cell research》1996,222(2):262
Fanconi anemia (FA) is an autosomal recessive disorder involving progressive pancytopenia, skeletal malformations, and a predisposition to leukemia. Thein vitrogrowth of FA fibroblasts is impaired, due to a defective G2 phase traverse of the cell cycle. Analyzing the cell cycle of lymphoid cell lines (LCLs) obtained from peripheral blood of FA patients by transformation with Epstein–Barr virus, we found a similar G2 phase defect, which was dependent upon the oxygen concentration. In addition, FA cells exhibited hypersensitivity towardcis-dichlorodiammineplatinum and mitomycin C, and moderate sensitivity towardtrans-dichlorodiammineplatinum. FA cells, however, showed no elevated sensitivity toward paraquat, an intracellular generator of superoxide radicals, or cumene hydroperoxide, a model organic peroxide. Chelating iron with low concentrations ofo-phenanthrolin improved cell proliferation and G2 phase transit of FA cells at 20% oxygen, but little at 5% oxygen. LCL cultures from healthy subjects were inhibited in their proliferation rate at all concentrations ofo-phenanthrolin. Exposure to excess iron, on the other hand, was very toxic to FA cells at 20%, but less toxic at 5% oxygen. In conclusion, the FA mutation leads to a cell cycle defect, which is expressed in cultures of lymphoid cells from FA patients, and involves hypersensitivity toward bifunctional alkylating agents, oxygen, and iron. 相似文献
879.
Reactions between sulfur diimides R(NSN)R′ (R=R′=tBu (1a), SiMe3 (1b), SnMe3 (1c); R=tBu, R′=SnMe3 (1d); R=SiMez3, R′=SnMe3 (1e)) and various organoboranes were studied, and the products were characterized by multinuclear magnetic resonance data (1H, 11B, 13C, 15N, 29Si and 119Sn NMR). Tetraalkyldiboranes(6) (Et2BH2BEt2 (2), dimeric 9-borobicyclo[3,3.1]nonane (3)) react with 1a and 1b by 1,3-hydroboration to give the N-sulfanyl-dialkylaminoboranes 4 and 5 which are instable with respect to eliminatio of short-lived [R---NS]. Trialkylboranes (Et3B (8)) react only sluggishly with 1a, but more readily with 1b mainly via S-ethylation, formally a 1,2-ethyloboration, to give the diethylborylamido-imino-ethanesulfinic acid 9b decomposes slowly at room temperature via ethene elimination to give 4b, followed by further decomposition via [R---NS] elimination. The compounds 9 can be prepared independently from the reaction between the N-lithio-imino-ethanesulfinic acid amide 10 and diorganoboron halides. The molecular structure of the lithium amide 10a (R=R′=tBu) was determined by X-ray analysis as a dimer in which the four nitrogen, two sulfur and two lithium atoms adopt a boat conformation, in contrast with other known derivatives of this type. If the sulfur diimides bear at least one trimethylstannyl group (1c-e), their reactions with Et3B (8), iPr3B (12) or 9-iso-butyl-9-borabicyclo[3,3,1]nonane (13) lead to the novel aminoboranes 14–16. These are products of a 1,1,-organoboration, since the Me3Sn group moves from one nitrogen atom to the other, and both the boryl and an alkyl group end up at the same nitrogen atom. 相似文献
880.
Bernd Schäppi 《Oecologia》1996,106(1):93-99
Leaf expansion, population dynamics and reproduction under elevated CO2 were studied for two dominant and four subdominant species in a high alpine grassland (2500 above sea level, Swiss Central Alps). Plots of alpine heath were exposed to 335 l l-1 and 680 l l-1 CO2 in open-top chambers over three growing seasons. Treatments also included natural and moderately improved mineral nutrient supply (40 kg N ha-1 year-1 in an NPK fertilizer mix). Seasonal dynamics of leaf expansion, which was studied for the dominant graminoid Carex curvula only, were not affected by elevated CO2 during two warm seasons or during a cool season. Improved nutrient supply increased both the expansion rate and the duration of leaf growth but elevated CO2 did not cause any further stimulation. Plant and tiller density (studied in all species) increased under elevated CO2 in the codominant Leontodon helveticus and the subdominant Trifolium alpinum, remained unchanged in two other minor species Poa alpina and Phyteuma globulariifolium, and decreased in Carex curvula. In Potentilla aurea elevated CO2 compensated for a natural decline in shoot number. By year 3 the number of fertile shoots in Leontodon and individual seed weight in Carex were slightly increased under elevated CO2, indicating CO2 effects on sexual reproduction in these two dominant species. The results suggest that the effects of elevated CO2 on the population dynamics of the species studied were not general, but species-specific and rather moderate effects. However, the reduction of tiller density in Carex curvula, in contrast to the increases observed in Leontodon helveticus and Trifolium alpinum, indicates that elevated CO2 may negatively affect the abundance of the species most characteristic of this alpine plant community. 相似文献