Abstract:
:Oocytes of Xenopus laevis in pachytene and early diplotene of meiosis have been studied using the Miller spreading technique. Transcription first appears in germinal vesicles 25-40 micrometers in diameter, when the oocyte is in early diplotene. Transcription at this stage consists of arrays of short RNP transcripts, irregularly distributed along the DNP axis. Linear regression analysis has shown that many of these arrays are transcription units (Type I) with the transcripts having a common point of origin. The lengths of these early transcription units (mean = 7.06 +/- 5.06 micrometers), calculated from the linear regression data, are comparable to the lengths of transcription units from later stages, including Dumont stage 3. The polymerase granules of Type I transcription units are widely and irregularly spaced, having a mean spacing of 505 +/- 748 nm. More advanced transcription units (Type II, mean length = 8.72 +/- 3.77 micrometer) are usually found in the same chromosome set as the Type I units. Type II transcription units have closer and more regularly spaced polymerase granules than Type I transcription units (mean spacing = 92 +/- 49 nm). Both Type I and II transcription units have comparatively short RNP transcripts, the mean values for the slopes of their regression lines being 0.1336 and 0.1440 respectively. By the time the germinal vesicles are about 50-60 micrometers in diameter the transcription units have a quite different morphology (Type III). The lengths of the Type III transcription units are comparable to the Type I and II units, the mean length being 6.34 +/- 4.03 micrometers. The spacing of the polymerase granules in the Type III units is closer and more regular than the earlier stages (70 +/- 40 nm). Another significant difference between Type III and Types I and II transcription units is a decrease in the foreshortening of the Type III RNP transcripts. The mean slope of the regression lines for Type III transcription units is 0.2439. The morphological appearance of the Type III transcription unit is virtually identical to that of the transcription units from Dumont stage 3 oocytes, both with respect to the length and the spacing of the polymerase granules. However, the transcripts in Type III transcription units are still more foreshortened than those of Dumont stage 3 oocytes, having mean regression slopes of 0.4728. From the data obtained in the present study, it has been concluded that the pattern of lampbrush-type transcription is virtually fully established by the time most germinal vesicles are about 50 micrometers in diameter.
journal_name
J Cell Scijournal_title
Journal of cell scienceauthors
Hill RS,Macgregor HCsubject
Has Abstractpub_date
1980-08-01 00:00:00pages
87-101eissn
0021-9533issn
1477-9137journal_volume
44pub_type
杂志文章abstract::Errors during the first meiotic division are common in our species, but virtually all occur during female meiosis. The reason why oogenesis is more error prone than spermatogenesis remains unknown. Normal segregation of homologous chromosomes at the first meiotic division (MI) requires coordinated behavior of the sist...
journal_title:Journal of cell science
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abstract::The microtubule-associated protein tau is a developmentally regulated family of neuronal phosphoproteins that promotes the assembly and stabilization of microtubules. The carboxy-terminal half of the protein contains three copies of an imperfectly repeated sequence; this region has been found to bind microtubules in v...
journal_title:Journal of cell science
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abstract::Myofibrillar proteins assemble to form the highly ordered repetitive contractile structural unit known as a sarcomere. Studies of myogenesis in vertebrate cell culture and embryonic developmental systems have identified some of the processes involved during sarcomere formation. However, isoform changes during vertebra...
journal_title:Journal of cell science
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doi:10.1242/jcs.01024
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abstract::According to the hypothesis of contact inhibition of movement, cells in a confluent monolayer are restrained from major overlapping by a directional inhibition of locomotion. This explanation of monolayering proposes that contact between 2 cells locally paralyses the locomotory function, preventing movement in the dir...
journal_title:Journal of cell science
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更新日期:1978-04-01 00:00:00
abstract::The end1 mutant belongs to a group of four vacuolar protein sorting mutants (class C vps) that lack a morphologically distinguishable and functional vacuole. These mutants share several other phenotypes, such as the inability to grow at 37 degrees C or on nonfermentable carbon sources. We show that, as in the case of ...
journal_title:Journal of cell science
pub_type: 杂志文章
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更新日期:1990-11-01 00:00:00
abstract::The HB2 cell line, developed from luminal epithelial cells cultured from milk, forms ball-like structures in collagen gels which show a uniform branching response to hepatocyte growth factor. The alpha2beta1 integrin is the major integrin expressed by luminal epithelial cells, and the role of this integrin in mammary ...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1998-02-01 00:00:00
abstract::It has been shown previously that whilst the rat type I integral membrane protein TGN38 (ratTGN38) is predominantly localised to the trans-Golgi network this protein does reach the cell surface from where it is internalised and delivered back to the trans-Golgi network. This protein thus provides a suitable tool for t...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1998-12-01 00:00:00
abstract::Chromatin is no longer considered to be a static structural framework for packaging DNA within the nucleus but is instead believed to be an interactive component of DNA metabolism. The ordered assembly of chromatin produces a nucleoprotein template capable of epigenetically regulating the expression and maintenance of...
journal_title:Journal of cell science
pub_type: 杂志文章,评审
doi:
更新日期:2000-08-01 00:00:00
abstract::Patients with myotonic dystrophy type 1 exhibit a diversity of symptoms that affect many different organs. Among these are cognitive dysfunctions, the origin of which has remained elusive, partly because of the difficulty in accessing neural cells. Here, we have taken advantage of pluripotent stem cell lines derived f...
journal_title:Journal of cell science
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abstract::Brain-derived neurotrophic factor (BDNF) is encoded by multiple mRNA variants whose differential subcellular distribution constitutes a 'spatial code' for local translation of BDNF and selective morphological remodeling of dendrites. Here, we investigated where BDNF translation takes place and what are the signaling p...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:10.1242/jcs.177626
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journal_title:Journal of cell science
pub_type: 杂志文章
doi:10.1242/jcs.051482
更新日期:2009-09-01 00:00:00
abstract::NADH:ubiquinone oxidoreductases catalyse the first step within the diverse pathways of mitochondrial NADH oxidation. In addition to the energy-conserving form commonly called complex I, fungi and plants contain much simpler alternative NADH:ubiquinone oxido-reductases that catalyze the same reaction but do not translo...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-07-01 00:00:00
abstract::5'AMP nucleotidase activity was localized by electron microscopy in Dictyostelium discoideum during cell differentiation. In addition, the activity was assayed by micro enzymic methods in sections dissected from specific cellular regions of lyophilized individuals. The results of the 2 procedures were in agreement, de...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1980-10-01 00:00:00
abstract::Serotonin receptors 5-HT(1A) and 5-HT(7) are highly coexpressed in brain regions implicated in depression. However, their functional interaction has not been established. In the present study we show that 5-HT(1A) and 5-HT(7) receptors form heterodimers both in vitro and in vivo. Foerster resonance energy transfer-bas...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:10.1242/jcs.101337
更新日期:2012-05-15 00:00:00
abstract::How cell fate becomes restricted during somatic cell differentiation is a long-lasting question in biology. Epigenetic mechanisms not present in pluripotent cells and acquired during embryonic development are expected to stabilize the differentiated state of somatic cells and thereby restrict their ability to convert ...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:10.1242/jcs.113019
更新日期:2012-12-15 00:00:00
abstract::The Tec kinases represent the second largest family of mammalian non-receptor tyrosine kinases and are distinguished by the presence of distinct proline-rich regions and pleckstrin homology domains that are required for proper regulation and activation. Best studied in lymphocyte and mast cells, these kinases are crit...
journal_title:Journal of cell science
pub_type: 杂志文章,评审
doi:
更新日期:2002-08-01 00:00:00
abstract::The Down syndrome critical region (DSCR) on Chromosome 21 contains many genes whose duplication may lead to the major phenotypic features of Down syndrome and especially the associated mental retardation. However, the functions of DSCR genes are mostly unknown and their possible involvement in key brain developmental ...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:10.1242/jcs.000703
更新日期:2007-06-01 00:00:00
abstract::In trypanosomes, the flagellum is rooted in the flagellar pocket, a surface micro-domain that is the sole site for endocytosis and exocytosis. By analysis of anterograde or retrograde intraflagellar transport in IFT88RNAi or IFT140RNAi mutant cells, we show that elongation of the new flagellum is not required for flag...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:10.1242/jcs.035626
更新日期:2008-11-15 00:00:00
abstract::Cancers arising in the oesophageal epithelium are among the most common fatal tumors in the world. Despite this, comparatively little is known about the cell biology and organization of this tissue. Recently, in vitro and in vivo techniques developed over the past 30 years for the study of the epidermis have been appl...
journal_title:Journal of cell science
pub_type: 杂志文章,评审
doi:
更新日期:2002-05-01 00:00:00
abstract::Circadian rhythms exist in most living organisms. The general molecular mechanisms that are used to generate 24-hour rhythms are conserved among organisms, although the details vary. These core clocks consist of multiple regulatory feedback loops, and must be coordinated and orchestrated appropriately for the fine-tun...
journal_title:Journal of cell science
pub_type: 杂志文章,评审
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更新日期:2011-02-01 00:00:00
abstract::Expression of actin was examined in a cultured rat embryonic cell line 3Y1 and transformed cell lines that originated from 3Y1. An alpha-actin in addition to cytoplasmic beta- and gamma-actins was detected in 3Y1 by two-dimensional gel electrophoresis. This alpha-actin was hardly detected at all in the transformants i...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1990-08-01 00:00:00
abstract::Intracellular signal transduction occurs through cascades of reactions involving dozens of proteins that transmit signals from the cell surface, through a crowded cellular environment filled with organelles and a filamentous cytoskeleton, to specific targets. Numerous signaling molecules are immobilized or transiently...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:10.1242/jcs.01122
更新日期:2004-06-01 00:00:00
abstract::Rabbit muscle myosin subfragment S1 decorates 6 nm diameter filaments in Drosophila wing epidermal cells in the arrowhead fashion characteristic of the binding of subfragment S1 to actin filaments. The filaments in question are concentrated between microtubules that are mostly composed of 15 protofilaments and form ce...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1988-11-01 00:00:00
abstract::Hepatocyte growth factor, also known as scatter factor, is a pleiotropic cytokine, which stimulates cell motility, invasion, proliferation, survival and morphogenesis, and induces the expression of specific genes by activating its receptor tyrosine kinase. In this work we have isolated, characterized and used as agoni...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1998-01-01 00:00:00
abstract::Rac1 and Rac3 are highly homologous regulatory proteins that belong to the small GTPases of the Rho family. Previously, we showed that Rac3 induces cell rounding and prevents neuronal differentiation, in contrast to its close relative Rac1, which stimulates cell spreading and neuritogenesis. To explain these opposing ...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:10.1242/jcs.039958
更新日期:2009-06-15 00:00:00
abstract::Glomerular basement membrane (GBM) and podocalyxin are essential for podocyte morphology. We provide evidence of functional interconnections between basement membrane components (collagen IV and laminin), the expression of podocalyxin and the morphology of human glomerular epithelial cells (podocytes). We demonstrated...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:10.1242/jcs.01163
更新日期:2004-07-01 00:00:00
abstract::Polarity of many cell types is controlled by a protein complex consisting of Bazooka/PAR-3 (Baz), PAR-6 and atypical protein kinase C (aPKC). In Drosophila, the Baz-PAR-6-aPKC complex is required for the control of cell polarity in the follicular epithelium, in ectodermal epithelia and neuroblasts. aPKC is the main si...
journal_title:Journal of cell science
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更新日期:2009-10-15 00:00:00
abstract::Accurate chromosome segregation requires the spindle assembly checkpoint to be active at the onset of mitosis, before being silenced following chromosome alignment. p31(comet) is a checkpoint antagonist in that its inhibition delays mitotic exit, whereas its overexpression overrides the checkpoint. How exactly p31(com...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:10.1242/jcs.093286
更新日期:2011-11-15 00:00:00
abstract::Members of the PAR-1/MARK kinase family play critical roles in polarity and cell cycle control and are regulated by 14-3-3 scaffolding proteins, as well as the LKB1 tumour suppressor kinase and atypical protein kinase C (PKC). In this study, we initially investigated the mechanism underlying the interaction of mammali...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:10.1242/jcs.03097
更新日期:2006-10-01 00:00:00
abstract::Beta-arrestin 1 and beta-arrestin 2 are well-known negative regulators of G-protein-coupled receptor (GPCR) signaling. Upon GPCR activation, beta-arrestins translocate to the cell membrane and bind to the agonist-occupied receptors. This uncouples these receptors from G proteins and promotes their internalization, thu...
journal_title:Journal of cell science
pub_type: 杂志文章,评审
doi:10.1242/jcs.03338
更新日期:2007-01-15 00:00:00