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1.
Evidence for the presence of inhibitors of mitotic factors during G1 period in mammalian cells 总被引:6,自引:3,他引:3 下载免费PDF全文
Our earlier studies indicated that the mitotic factors, which induce germinal vesicle breakdown and chromosome condensation when injected into fully grown Xenopus oocytes, are preferentially associated with metaphase chromosomes and that they bind to chromatin as soon as they are synthesized during the G2 phase. In this study, we attempted to determine the fate of these factors as the cell completes mitosis and enters G1. Extracts from HeLa cells at different points during G1, S, and G2 periods were mixed with mitotic extracts in various proportions, incubated, and then injected into Xenopus oocytes to determine their maturation-promoting activity. The maturation-promoting activity of the mitotic extracts was neutralized by extracts of G1 cells during all stages of G1 but not by those of late S and G2 phase cells. Extracts of quiescent (G0) human diploid fibroblasts exhibited very little inhibitory activity. However, UV irradiation of G0 cells, which is known to cause decondensation of chromatin, significantly enhanced the inhibitory activity of extracts of these cells. These factors are termed inhibitors of mitotic factors (IMF). They seem to be activated, rather than newly synthesized, as the cell enters telophase when chromosomes begin to decondense. The IMF are nondialyzable, nonhistone proteins with a molecular weight of greater than 12,000. Since mitotic factors are known to induce chromosome condensation, it is possible that IMF, which are antagonistic to mitotic factors, may serve the reverse function of the mitotic factors, i.e., regulation of chromosome decondensation. 相似文献
2.
Digestion of fixed metaphase chromosomes by endonucleases (micrococcal nuclease and DNase II) under optimal digestion conditions followed by Giemsa staining produces sharp banding patterns identical to G-bands. In 3H-thymidine labeled, synchronized metaphase cells of the chinese hamster (CHO line), the band induction is accompanied by the removal of DNA. The single strand specific nuclease S1 and DNase I do not produce such banding patterns. 相似文献
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Mwanahamuntu MH Sahasrabuddhe VV Kapambwe S Pfaendler KS Chibwesha C Mkumba G Mudenda V Hicks ML Vermund SH Stringer JS Parham GP 《PLoS medicine》2011,8(5):e1001032
Groesbeck Parham and colleagues describe their Cervical Cancer Prevention Program in Zambia, which has provided services to over 58,000 women over the past five years, and share lessons learned from the program's implementation and integration with existing HIV/AIDS programs. 相似文献
5.
Ghantasala S Sameer Kumar Abhilash K Venugopal Anita Mahadevan Santosh Renuse H C Harsha Nandini A Sahasrabuddhe Harsh Pawar Rakesh Sharma Praveen Kumar Sudha Rajagopalan Keith Waddell Yarappa L Ramachandra Parthasarathy Satishchandra Raghothama Chaerkady T S Keshava Prasad K Shankar Akhilesh Pandey 《Clinical proteomics》2012,9(1):12
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Kapoor P Sahasrabuddhe AA Kumar A Mitra K Siddiqi MI Gupta CM 《The Journal of biological chemistry》2008,283(33):22760-22773
Leishmania actin was cloned, overexpressed in baculovirus-insect cell system, and purified to homogeneity. The purified protein polymerized optimally in the presence of Mg2+ and ATP, but differed from conventional actins in its following properties: (i) it did not polymerize in the presence of Mg2+ alone, (ii) it polymerized in a restricted range of pH 7.0-8.5, (iii) its critical concentration for polymerization was found to be 3-4-fold lower than of muscle actin, (iv) it predominantly formed bundles rather than single filaments at pH 8.0, (v) it displayed considerably higher ATPase activity during polymerization, (vi) it did not inhibit DNase-I activity, and (vii) it did not bind the F-actin-binding toxin phalloidin or the actin polymerization disrupting agent Latrunculin B. Computational and molecular modeling studies revealed that the observed unconventional behavior of Leishmania actin is related to the diverged amino acid stretches in its sequence, which may lead to changes in the overall charge distribution on its solvent-exposed surface, ATP binding cleft, Mg2+ binding sites, and the hydrophobic loop that is involved in monomer-monomer interactions. Phylogenetically, it is related to ciliate actins, but to the best of our knowledge, no other actin with such unconventional properties has been reported to date. It is therefore suggested that actin in Leishmania may serve as a novel target for design of new antileishmanial drugs. 相似文献
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The effect of trypsin on nuclease-resistant chromatin fragments 总被引:46,自引:0,他引:46
8.
A twinfilin‐like protein coordinates karyokinesis by influencing mitotic spindle elongation and DNA replication in Leishmania 下载免费PDF全文
Gaurav Kumar Lova P. Kajuluri Chhitar M. Gupta Amogh A. Sahasrabuddhe 《Molecular microbiology》2016,100(1):173-187
Twinfilin is an evolutionarily conserved actin‐binding protein, which regulates actin‐dynamics in eukaryotic cells. Homologs of this protein have been detected in the genome of various protozoan parasites causing diseases in human. However, very little is known about their core functions in these organisms. We show here that a twinfilin homolog in a human pathogen Leishmania, primarily localizes to the nucleolus and, to some extent, also in the basal body region. In the dividing cells, nucleolar twinfilin redistributes to the mitotic spindle and remains there partly associated with the spindle microtubules. We further show that approximately 50% depletion of this protein significantly retards the cell growth due to sluggish progression of S phase of the cell division cycle, owing to the delayed nuclear DNA synthesis. Interestingly, overexpression of this protein results in significantly increased length of the mitotic spindle in the dividing Leishmania cells, whereas, its depletion adversely affects spindle elongation and architecture. Our results indicate that twinfilin controls on one hand, the DNA synthesis and on the other, the mitotic spindle elongation, thus contributing to karyokinesis in Leishmania. 相似文献
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Docosahexaenoic acid up‐regulates both PI3K/AKT‐dependent FABP7–PPARγ interaction and MKP3 that enhance GFAP in developing rat brain astrocytes 下载免费PDF全文
10.
Xinyan Wu Muhammad Saddiq Zahari Santosh Renuse Nandini A. Sahasrabuddhe Min-Sik Kim Mary Jo Fackler Martha Stampfer Edward Gabrielson Saraswati Sukumar Akhilesh Pandey 《Clinical proteomics》2018,15(1):21