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Mitotic cytosol inhibits invagination of coated pits in broken mitotic cells 总被引:9,自引:3,他引:6 下载免费PDF全文
Receptor-mediated endocytosis is inhibited during mitosis in mammalian cells and earlier work on A431 cells suggested that one of the sites inhibited was the invagination of coated pits (Pypaert, M., J. M. Lucocq, and G. Warren. 1987. Eur. J. Cell Biol. 45: 23-29). To explore this inhibition further, we have reproduced it in broken HeLa cells. Mitotic or interphase cells were broken by freeze-thawing in liquid nitrogen and warmed in the presence of mitotic or interphase cytosol. Using a morphological assay, we found invagination to be inhibited only when mitotic cells were incubated in mitotic cytosol. This inhibition was reversed by diluting the cytosol during the incubation. Reversal was sensitive to okadaic acid, a potent phosphatase inhibitor, showing that phosphorylation was involved in the inhibition of invagination. This was confirmed using purified cdc2 kinase which alone could partially substitute for mitotic cytosol. 相似文献
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Identification of a Golgi-associated protein that undergoes mitosis dependent phosphorylation and relocation 总被引:2,自引:1,他引:1 下载免费PDF全文
By means of a monoclonal antibody (BH3), we have identified a 57-kD protein (p57) that in interphase is restricted largely to the perinuclear region of the cell. Double label immunofluorescence microscopy suggests localization of p57 to the Golgi complex and associated membranous structures. Protease protection experiments and chemical extractability indicate that p57 is a peripheral membrane protein exposed to the cytoplasm. p57 displays unique behavior during mitosis. At the end of G2 or in early prophase, p57 leaves the perinuclear region and accumulates very rapidly within the nucleus, at a time when the nuclear envelope is still intact and before nuclear lamina disassembly. This relocation of p57 coincides with its hyperphosphorylation on serine and threonine residues. After nuclear envelope breakdown p57 becomes uniformly distributed throughout the mitotic cytoplasm until in late telophase when it returns to its perinuclear location and is once again excluded from the nucleus. The behavior of p57 during mitosis suggests that it may play a role in the cellular reorganization evident during mitotic prophase. 相似文献
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Rates of DNA sequence evolution are not sex-biased in Drosophila melanogaster and D. simulans 总被引:2,自引:0,他引:2
To determine whether male- or female-biased mutation rates have affected
the molecular evolution of Drosophila melanogaster and D. simulans, we
calculated the male-to-female ratio of germline cell divisions ([symbol:
see text]) from germline generation data and the male-to-female ratio of
mutation rate ([symbol: see text]) by comparing chromosomal levels of
nucleotide divergence. We found that the ratio of germline cell divisions
changes from indicating a weak female bias to indicating a weak male bias
as the age of reproduction increases. The range of [symbol: see text]
values that we observed, however, does not lead us to expect much, if any,
difference in mutation rate between the sexes. Silent and intron nucleotide
divergence were compared between nine loci on the X chromosome and nine
loci on the second and third chromosomes. The average levels of nucleotide
divergence were not significantly different across the chromosomes,
although both silent and intron sites show a trend toward slightly more
divergence on the X. These results indicate a lack of sex- or
chromosome-biased molecular evolution in D. melanogaster and D. simulans.
相似文献
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Souter VL Parisi MA Nyholt DR Kapur RP Henders AK Opheim KE Gunther DF Mitchell ME Glass IA Montgomery GW 《Human genetics》2007,121(2):179-185
Traditionally twins are classified as dizygous or fraternal and monozygous or identical (Hall Twinning, 362, 2003 and 735-743). We report a rare case of 46,XX/46,XY twins: Twin A presented with ambiguous genitalia and Twin B was a phenotypically normal male. These twins demonstrate a third, previously unreported mechanism for twinning. The twins underwent initial investigation with 17-hydroxyprogesterone and testosterone levels, pelvic ultrasound and diagnostic laparoscopy. Cytogenetic analysis was performed on peripheral blood cells and skin fibroblasts. Histological examination and Fluorescence in situ hybridization studies on touch imprints were performed on gonadal biopsies. DNA analysis using more than 6,000 DNA markers was performed on skin fibroblast samples from the twins and on peripheral blood samples from both parents. Twin A was determined to be a true hermaphrodite and Twin B an apparently normal male. Both twins had a 46,XX/46,XY chromosome complement in peripheral lymphocytes, skin fibroblasts, and gonadal biopsies. The proportion of XX to XY cells varied between the twins and the tissues evaluated. Most significantly the twins shared 100% of maternal alleles and approximately 50% of paternal alleles in DNA analysis of skin fibroblasts. The twins are chimeric and share a single genetic contribution from their mother but have two genetic contributions from their father thus supporting the existence of a third, previously unreported type of twinning. 相似文献
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Lara Vojnov Sergio Carmona Clement Zeh Jessica Markby Debrah Boeras Marta R. Prescott Anthony L. H. Mayne Souleymane Sawadogo Christiane Adje-Toure Guoqing Zhang Mercedes Perez Gonzalez Wendy S. Stevens Meg Doherty Chunfu Yang Heather Alexander Trevor F. Peter John Nkengasong the DBS for VL Diagnostics Investigation Consortium 《PLoS medicine》2022,19(8)
BackgroundAccurate routine HIV viral load testing is essential for assessing the efficacy of antiretroviral treatment (ART) regimens and the emergence of drug resistance. While the use of plasma specimens is the standard for viral load testing, its use is restricted by the limited ambient temperature stability of viral load biomarkers in whole blood and plasma during storage and transportation and the limited cold chain available between many health care facilities in resource-limited settings. Alternative specimen types and technologies, such as dried blood spots, may address these issues and increase access to viral load testing; however, their technical performance is unclear. To address this, we conducted a meta-analysis comparing viral load results from paired dried blood spot and plasma specimens analyzed with commonly used viral load testing technologies.Methods and findingsStandard databases, conferences, and gray literature were searched in 2013 and 2018. Nearly all studies identified (60) were conducted between 2007 and 2018. Data from 40 of the 60 studies were included in the meta-analysis, which accounted for a total of 10,871 paired dried blood spot:plasma data points. We used random effects models to determine the bias, accuracy, precision, and misclassification for each viral load technology and to account for between-study variation. Dried blood spot specimens produced consistently higher mean viral loads across all technologies when compared to plasma specimens. However, when used to identify treatment failure, each technology compared best to plasma at a threshold of 1,000 copies/ml, the present World Health Organization recommended treatment failure threshold. Some heterogeneity existed between technologies; however, 5 technologies had a sensitivity greater than 95%. Furthermore, 5 technologies had a specificity greater than 85% yet 2 technologies had a specificity less than 60% using a treatment failure threshold of 1,000 copies/ml. The study’s main limitation was the direct applicability of findings as nearly all studies to date used dried blood spot samples prepared in laboratories using precision pipetting that resulted in consistent input volumes.ConclusionsThis analysis provides evidence to support the implementation and scale-up of dried blood spot specimens for viral load testing using the same 1,000 copies/ml treatment failure threshold as used with plasma specimens. This may support improved access to viral load testing in resource-limited settings lacking the required infrastructure and cold chain storage for testing with plasma specimens.Lara Vojnov and co-workers report on the use of dried blood spots for HIV viral load testing. 相似文献
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The establishment of the apical-basal axis is a critical event in plant embryogenesis, evident from the earliest stages onwards. Polarity is evident in the embryo sac, egg cell, zygote, and embryo-suspensor complex. In the embryo-proper, two functionally distinct meristems form at each pole, through the localized expression of key genes. A number of mutants, notably of the model genetic organism Arabidopsis thaliana, have revealed new gene functions that are required for patterning of the apical-basal axis. There is now increasing evidence that two particular modes of signalling, via auxin and cell wall components, play important roles in co-ordinating the gene expression programmes that define determinative roles in the establishment of polarity. 相似文献
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Tau is a microtubule‐associated protein whose function has been investigated primarily in neurons. Recently, tau expression has been correlated with increased drug resistance in various cancers of non‐neuronal tissues. In this report, we investigate the tau expressed in cancerous prostate lines ALVA‐31, DU 145, and PC‐3. Prostate cancer tau is heat‐stable and highly phosphorylated, containing many of the modifications identified in Alzheimer's disease brain tau. RT‐PCR and phosphatase treatment indicated that all six alternatively spliced adult brain tau isoforms are expressed in ALVA‐31 cells, and isoforms containing exon 6 as well as high molecular weight tau isoforms containing either exon 4A or a larger splice variant of exon 4A are also present. Consistent with its hyperphosphorylated state, a large proportion of ALVA‐31 tau does not bind to microtubules, as detected by confocal microscopy and biochemical tests. Finally, endogenous ALVA‐31 tau can interact with the p85 subunit of phosphatidylinositol 3‐kinase, as demonstrated by co‐immunoprecipitations and in vitro protein‐binding assays. Our results suggest that tau in prostate cancer cells does not resemble that from normal adult brain and support the hypothesis that tau is a multifunctional protein. J. Cell. Biochem. 108: 555–564, 2009. © 2009 Wiley‐Liss, Inc. 相似文献
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Nicola VL Serão Kristin R Delfino Bruce R Southey Jonathan E Beever Sandra L Rodriguez-Zas 《BMC medical genomics》2011,4(1):1-21