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Oat (Avena sativa L.) mesophyll protoplasts were recently demonstrated to be capable of dedifferentiation, repeated divisions, and colony formation. Since the development of oat mesophyll protoplasts is decisively influenced by the nature of the used feeder culture (species, variety and concentration), we conducted a systematic study of this parameter. Generally, graminaceous feeders promoted protoplast proliferation, while dicot species repressed protoplast divisions. The beneficial effect of those feeders that promote divisions was counterbalanced by a factor that causes necrosis. The correct balance between promotion of divisions or necrosis depended on the nature of the feeder and its plating density. 相似文献
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Nora Wender Jan Hegermann Bettina Brunner Brigitte Nuscher Tim Bartels Armin Giese Klaus Beyer Stefan Eimer Konstanze F Winklhofer Christian Haass 《The EMBO journal》2010,29(20):3571-3589
Aggregation of α‐synuclein (αS) is involved in the pathogenesis of Parkinson's disease (PD) and a variety of related neurodegenerative disorders. The physiological function of αS is largely unknown. We demonstrate with in vitro vesicle fusion experiments that αS has an inhibitory function on membrane fusion. Upon increased expression in cultured cells and in Caenorhabditis elegans, αS binds to mitochondria and leads to mitochondrial fragmentation. In C. elegans age‐dependent fragmentation of mitochondria is enhanced and shifted to an earlier time point upon expression of exogenous αS. In contrast, siRNA‐mediated downregulation of αS results in elongated mitochondria in cell culture. αS can act independently of mitochondrial fusion and fission proteins in shifting the dynamic morphologic equilibrium of mitochondria towards reduced fusion. Upon cellular fusion, αS prevents fusion of differently labelled mitochondrial populations. Thus, αS inhibits fusion due to its unique membrane interaction. Finally, mitochondrial fragmentation induced by expression of αS is rescued by coexpression of PINK1, parkin or DJ‐1 but not the PD‐associated mutations PINK1 G309D and parkin Δ1–79 or by DJ‐1 C106A. 相似文献
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Heidi LandmesserAnke Stein Bettina BlüschkeMelanie Brinkmann Sabine HunkeErwin Schneider 《生物化学与生物物理学报:生物膜》2002,1565(1):64-72
The maltose ATP-binding cassette (ABC) transporter of Salmonella typhimurium is composed of a membrane-associated complex (MalFGK2) and a periplasmic substrate binding protein. To further elucidate protein-protein interactions between the subunits, we have studied the dissociation and reassembly of the MalFGK2 complex at the level of purified components in proteoliposomes. First, we optimized the yield in purified complex protein by taking advantage of a newly constructed expression plasmid that carries the malK, malF and malG genes in tandem orientation. Incorporated in proteoliposomes, the complex exhibited maltose binding protein/maltose-dependent ATPase activity with a Vmax of 1.25 μmol Pi/min/mg and a Km of 0.1 mM. ATPase activity was sensitive to vanadate and enzyme IIAGlc, a component of the enterobacterial glucose transport system. The proteoliposomes displayed maltose transport activity with an initial rate of 61 nmol/min/mg. Treatment of proteoliposomes with 6.6 M urea resulted in the release of medium-exposed MalK subunits concomitant with the complete loss of ATPase activity. By adding increasing amounts of purified MalK to urea-treated proteoliposomes, about 50% of vanadate-sensitive ATPase activity relative to the control could be recovered. Furthermore, the phenotype of MalKQ140K that exhibits ATPase activity in solution but not when associated with MalFG was confirmed by reassembly with MalK-depleted proteoliposomes. 相似文献
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Two euplanktonic ciliates, Urotricha psenneri n. sp. (Prostomatida) and Amphileptus piger (Vuxanovici, 1962) n. comb. (Pleurostomatida), were discovered in the surface plankton of the oligotrophic Lake Traunsee in Austria. Their morphology and infraciliature were studied in live cells as well as in specimens impregnated with protargol and silver nitrate. Urotricha psenneri is a small urotrichid, less than 50 microm length and with a single caudal cilium. It is unique in having (i) a massive oral basket projecting as a conspicuous bulge with cylindrical microfibrillar annulus and (ii) a curved brosse row 1 in the broad, barren circumoral area. Amphileptus piger (Vuxanovici, 1962) is about 55 x 13 microm in vivo, has two macronuclear nodules with a single micronucleus in between in the posterior body half, has a single contractile vacuole with a terminal excretory pore, and few, but thick and thus highly conspicuous extrusomes. The amphileptid ciliary pattern (spica) is difficult to recognise due to the widely spaced basal bodies. 相似文献
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Böttcher C von Roepenack-Lahaye E Schmidt J Schmotz C Neumann S Scheel D Clemens S 《Plant physiology》2008,147(4):2107-2120
Metabolomics is facing a major challenge: the lack of knowledge about metabolites present in a given biological system. Thus, large-scale discovery of metabolites is considered an essential step toward a better understanding of plant metabolism. We show here that the application of a metabolomics approach generating structural information for the analysis of Arabidopsis (Arabidopsis thaliana) mutants allows the efficient cataloging of metabolites. Fifty-six percent of the features that showed significant differences in abundance between seeds of wild-type, transparent testa4, and transparent testa5 plants could be annotated. Seventy-five compounds were structurally characterized, 21 of which could be identified. About 40 compounds had not been known from Arabidopsis before. Also, the high-resolution analysis revealed an unanticipated expansion of metabolic conversions upstream of biosynthetic blocks. Deficiency in chalcone synthase results in the increased seed-specific biosynthesis of a range of phenolic choline esters. Similarly, a lack of chalcone isomerase activity leads to the accumulation of various naringenin chalcone derivatives. Furthermore, our data provide insight into the connection between p-coumaroyl-coenzyme A-dependent pathways. Lack of flavonoid biosynthesis results in elevated synthesis not only of p-coumarate-derived choline esters but also of sinapate-derived metabolites. However, sinapoylcholine is not the only accumulating end product. Instead, we observed specific and sophisticated changes in the complex pattern of sinapate derivatives. 相似文献
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Jakub Horák Christopher Grefen Kenneth W Berendzen Achim Hahn York-Dieter Stierhof Bettina Stadelhofer Mark Stahl Csaba Koncz Klaus Harter 《BMC plant biology》2008,8(1):77