排序方式: 共有28条查询结果,搜索用时 203 毫秒
11.
Dyall SD Yan W Delgadillo-Correa MG Lunceford A Loo JA Clarke CF Johnson PJ 《Nature》2004,431(7012):1103-1107
Trichomonas vaginalis is a unicellular microaerophilic eukaryote that lacks mitochondria yet contains an alternative organelle, the hydrogenosome, involved in pyruvate metabolism. Pathways between the two organelles differ substantially: in hydrogenosomes, pyruvate oxidation is catalysed by pyruvate:ferredoxin oxidoreductase (PFOR), with electrons donated to an [Fe]-hydrogenase which produces hydrogen. ATP is generated exclusively by substrate-level phosphorylation in hydrogenosomes, as opposed to oxidative phosphorylation in mitochondria. PFOR and hydrogenase are found in eubacteria and amitochondriate eukaryotes, but not in typical mitochondria. Analyses of mitochondrial genomes indicate that mitochondria have a single endosymbiotic origin from an alpha-proteobacterial-type progenitor. The absence of a genome in trichomonad hydrogenosomes precludes such comparisons, leaving the endosymbiotic history of this organelle unclear. Although phylogenetic reconstructions of a few proteins indicate that trichomonad hydrogenosomes share a common origin with mitochondria, others do not. Here we describe a novel NADH dehydrogenase module of respiratory complex I that is coupled to the central hydrogenosomal fermentative pathway to form a hydrogenosomal oxidoreductase complex that seems to function independently of quinones. Phylogenetic analyses of hydrogenosomal complex I-like proteins Ndh51 and Ndh24 reveal that neither has a common origin with mitochondrial homologues. These studies argue against a vertical origin of trichomonad hydrogenosomes from the proto-mitochondrial endosymbiont. 相似文献
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Anske Van den Abbeele Sarah De Clercq Ariane De Ganck Veerle De Corte Berlinda Van Loo Sameh Hamdy Soror Vasundara Srinivasan Jan Steyaert Joël Vandekerckhove Jan Gettemans 《Cellular and molecular life sciences : CMLS》2010,67(9):1519-1535
RNA interference has tremendously advanced our understanding of gene function but recent reports have exposed undesirable
side-effects. Recombinant Camelid single-domain antibodies (VHHs) provide an attractive means for studying protein function without affecting gene expression.
We raised VHHs against gelsolin (GsnVHHs), a multifunctional actin-binding protein that controls cellular actin organization
and migration. GsnVHH-induced delocalization of gelsolin to mitochondria or the nucleus in mammalian cells reveals distinct
subpopulations including free gelsolin and actin-bound gelsolin complexes. GsnVHH 13 specifically recognizes Ca2+-activated gelsolin (K
d ~10 nM) while GsnVHH 11 binds gelsolin irrespective of Ca2+ (K
d ~5 nM) but completely blocks its interaction with G-actin. Both GsnVHHs trace gelsolin in membrane ruffles of EGF-stimulated
MCF-7 cells and delay cell migration without affecting F-actin severing/capping or actin nucleation activities by gelsolin.
We conclude that VHHs represent a potent way of blocking structural proteins and that actin nucleation by gelsolin is more
complex than previously anticipated. 相似文献
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贾巍巍 《山西师范大学学报:自然科学版》2004,18(3):6-11
本文讨论F4上n维线性空间的k维子空间W,这些子空间都有特定的自同构群(实际上是典型群GLn(F4)的一个子群),根据群中元素形式的不同可将子空间W分为两类,并对寻找n维空间中形如这两类的n/2维自对偶子空间提供了一种采用降低维数寻找的方法。 相似文献
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多梯度复杂图像的分割 总被引:1,自引:1,他引:0
图像分割是一种重要的图像分析技术,它不仅得到人们广泛的重视和研究,也在实际中得到大量的应用。本文针对一些经典分割算法对多梯度复杂图像分割边缘定位不准确,易受噪声干扰的特点,提出了一种利用图像边缘区域对多梯度复杂图像进行自适应阈值分割的算法。通过对各种算法的比较,本算法抗干扰能力较强,稳定性好,而且完全自动,不需预先设定任何参数。对多种图像的实验表明本文方法十分有效。 相似文献
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孤岛油田馆(1 2)砂层组属于河流相沉积,其纵向、横向相变迅速,砂体难以大面积追踪,本利用河流结构单元分析法、标准层与辅助标志层控制下的“旋回-厚度”对比法,很好地解决了馆(1 2)地层的划分对比问题,其中馆(1 2)砂层组内辅助标志层的发现为地层的划分对比提供了重要的保证.根据结构单元分析、砂体的岩性特征、粒度特征、河流砂体的空间展布形态以及河流曲率的计算,对馆(1 2)河流沉积的垂向旋回性及沉积模式进行了研究。对比Miall的16种河流分类方案,孤岛油田馆(1 2)砂层组属于细粒曲流河沉积. 相似文献
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G. A. Gerencser S. Y. Loo K. M. Cornette 《Cellular and molecular life sciences : CMLS》1982,38(8):956-957
Summary Stimulation of active Na+ transport in the toad skin by antidiuretic hormone (ADH) and p-chloromecuribenzoate (P-CMB) was blunted by the presence of silver (Ag+). Amiloride inhibited active Na+ transport, equivalently, whether Ag+ was present or not.This work was supported by the Nephrology Training grant from the National Institute of Arthritis and Metabolic Diseases (1-TO1-AM-05697-02 and –03) and by Whitehall Foundation grant No. 78-156 ck-1 DSR. 相似文献
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Summary A method is described that allows blood samples to be taken repeatedly from the suprarenal vein, without changing the circulation in the adrenal glands or eliciting reflexes which could interfere with the adrenalin secretion. The vasoconstrictor properties of the blood samples are tested on an isolated blood vessel preparation. 相似文献
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Mechanism of alkylation of nucleic acids by nitrosodimethylamine 总被引:6,自引:0,他引:6