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821.
Enrico D. Perini Ramona Schaefer Martin Stöter Yannis Kalaidzidis Marino Zerial 《Traffic (Copenhagen, Denmark)》2014,15(12):1366-1389
Early endosomes are organized in a network of vesicles shaped by cycles of fusion, fission, and conversion to late endosomes. In yeast, endosome fusion and conversion are regulated, among others, by CORVET, a hexameric protein complex. In the mammalian endocytic system, distinct subpopulations of early endosomes labelled by the Rab5 effectors APPL1 and EEA1 are present. Here, the function of mammalian CORVET with respect to these endosomal subpopulations was investigated. Tgfbrap1 as CORVET‐specific subunit and functional ortholog of Vps3p was identified, demonstrating that it is differentially distributed between APPL1 and EEA1 endosomes. Surprisingly, depletion of CORVET‐specific subunits caused fragmentation of APPL1‐positive endosomes but not EEA1 endosomes in vivo. These and in vitro data suggest that CORVET plays a role in endosome fusion independently of EEA1. Depletion of CORVET subunits caused accumulation of large EEA1 endosomes indicative of another role in the conversion of EEA1 endosomes into late endosomes. In addition, depletion of CORVET‐specific subunits caused alterations in transport depending on both the type of cargo and the specific endosomal subpopulation. These results demonstrate that CORVET plays distinct roles at multiple stages in the mammalian endocytic pathway. 相似文献
822.
Wu-Jie Su Bing Li Wei-De Shen Yan Wu Shan-Ying Zhu Ying Sun Wen-Bing Wang 《Biologia》2009,64(2):383-387
Bombyx mori nucleopolyhedrovirus (BmNPV) orf4 has been shown to be expressed at very early stage of Bm-NPV infection cycle. In this study, using transient expression experiment,
we demonstrated for the first time that orf4 promoter is an immediate early promoter, indicating that orf4 may play a role in the immediate-early stage of BmNPV infection. Moreover, with the recently developed Bac-to-Bac/BmNPV baculovirus
expression system and a modified pFast-Bac1 whose polyhedrin promoter was replaced with orf4 promoter, a recombinant bacmid baculovirus expressing enhanced green fluorescent protein (EGFP) under the control of orf4 promoter in Bombyx mori (Bm) cells was successfully constructed. The result not only showed that the polyhedrin promoter can be replaced easily with
other promoters to direct the expression of foreign genes by using this novel system but also laid the foundation for the
rescue experiment of orf4 deletion mutant. 相似文献
823.
824.
ANA RIESGO MANUEL MALDONADO 《Biological journal of the Linnean Society. Linnean Society of London》2009,97(2):413-426
The demosponge Crambe crambe shows a peculiar spermatogenesis, hard to be reconciled with the basal position of sponges in the animal phylogeny. Early spermatogenesis stages showed most of the simple features expected in sponges. However, spermiogenesis departed from the anticipated process. Spermatids lengthened remarkably, forming a deep cytoplasmic pit around the cilium insertion, with the proximal axoneme bending to produce a V-shaped spermatozoon surprisingly similar to that known in the phylum Phoronida. The cytology was unexpectedly complex, with a needle-like nucleus of helically condensed chromatin, a conical acrosome with a subacrosomal rod, and a mitochondrion connected to the basal body by striated rootlets. These findings establish that the spermatozoon of broad-casting demosponges occurs in two structural categories ('primitive' and 'modified' type). This dualistic condition must necessarily have pre-dated the evolutionary apparition of higher metazoans, if we are to keep regarding sponges as the most primitive animals. We hypothesize that internal fertilization in C. crambe – and incidentally other demosponges – may depart from the general model assumed for spermcasting sponges. The V-shape of this spermatozoon suggests a design to favour autonomous penetration through the dense mesohyl to reach the oocytes, rather than engulfment and transportation by carrier cells towards the oocyte. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 413–426. 相似文献
825.
826.
SANDRINE LADEVÈZE CHRISTIAN DE MUIZON 《Zoological Journal of the Linnean Society》2010,159(3):746-784
New metatherian petrosal bones from the mid to Late Palaeocene of Itaboraí, belonging to three morphotypes (VI, VII, and VII), are formally described and compared to fossil and extant taxa known by their auditory region. An attempt at assigning petrosal types to tooth‐based taxa from Itaboraí was made by combining parsimony and morphometric methods. The first large scale phylogenetic analysis of the Itaboraían metatherians, involving basicranial and dental characters in a larger number of taxa, is provided here and is at the basis of a systematic revision of the metatherians from Itaboraí. The combination of morphometric and cladistic analyses helps in understanding the affinities between the petrosals and the tooth‐based taxa. The metatherians from Itaboraí were taxonomically diverse, belonging to each of the most important radiations in marsupial evolutionary history (Didelphimorphia, Paucituberculata, Eometatheria). The inclusion of Palaeocene taxa in the crown group Marsupialia and above all in the Eometatheria radiation points to an early emergence of these clades in South America and corroborates the main molecular hypotheses. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 159 , 746–784. 相似文献
827.
828.
microRNA(miRNA)是一类自然形成的非编码小RNA,不少miRNA分子已被证实与癌症的生成有关联。近期的研究发现人血清中稳定存在一定水平的miRNA,并且血清miRNA表达谱的变化与多种肿瘤的发生、发展具有明确的相关性,说明血清miRNA可以作为肿瘤临床诊断和预后评估的分子标志物。因此,特定的血清miRNA表达谱可以构成识别癌症与其他疾病的"指纹",为癌症及其他疾病的诊断提供一种新的非侵入性的检测方法,同时,该技术还可用于肿瘤分类、预后判断、手术疗效监测及疾病复发预测等领域,并可能带来未来临床医学上的变革。 相似文献
829.
830.
Regulation of polyamine synthesis in human hepatocytes by hepatotrophic factor augmenter of liver regeneration 总被引:5,自引:0,他引:5
Dayoub R Thasler WE Bosserhoff AK Singer T Jauch KW Schlitt HJ Weiss TS 《Biochemical and biophysical research communications》2006,345(1):181-187
Different stages of liver regeneration are regulated by a variety of factors such as the liver growth associated protein ALR, augmenter of liver regeneration. Furthermore, small molecules like polyamines were proven to be essential for hepatic growth and regeneration. Therefore, using primary human hepatocytes in vitro we investigated the effect of ALR on the biosynthesis of polyamines. We demonstrated by HPLC analysis that recombinant ALR enhanced intracellular hepatic putrescine, spermidine, and spermine levels within 9-12h. The activation of polyamine biosynthesis was dose dependent with putrescine showing the strongest increase. Additionally, ALR treatment induced mRNA expression of ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase, both key enzymes of polyamine biosynthesis. Further, ALR induced c-myc mRNA expression, a regulator of ODC expression, and therefore we assume that ALR exerts its liver regeneration augmenting effects through stimulation of its signalling pathway leading in part to enhanced polyamine synthesis. 相似文献