Abstract:
:Xenopus embryos initiate replication at random closely spaced sites until a certain concentration of nuclei is achieved within the embryo, after which fewer, more specific chromosomal sites are utilized as origins. We have examined the relationship between nucleo-cytosolic ratio and origin specification when Chinese hamster ovary (CHO) cell nuclei are introduced into Xenopus egg extracts. At concentrations of intact late-G1-phase nuclei that approximate early Xenopus embryos, the entire genome was duplicated nearly 4 times faster than in culture, accompanied by a de-localization of initiation sites at the dihydrofolate reductase (DHFR) locus. As the concentration of nuclei was increased, the number of initiation sites per nucleus decreased and initiation at the DHFR locus became localized to the physiologically utilized DHFR origin. Origin specification was optimal at nuclear concentrations that approximate the Xenopus mid-blastula transition (MBT). Higher concentrations resulted in an overall inhibition of DNA synthesis. By contrast, with intact early G1-phase nuclei, replication initiated at apparently random sites at all concentrations, despite an identical relationship between nucleo-cytosolic ratio and replicon size. Furthermore, permeabilization of late-G1-phase nuclei, using newly defined conditions that preserve the overall rate of replication, eliminated site-specificity, even at nuclear concentrations optimal for DHFR origin recognition. These data show that both nucleo-cytosolic ratio and nuclear structure play important but independent roles in the regulation of replication origin usage. Nucleo-cytosolic ratio clearly influences the number of replication origins selected. However, titration of cytosolic factors is not sufficient to focus initiation to specific sites. An independent mechanism, effecting changes within G1-phase nuclei, dictates which of many potential initiation sites will function as an origin.
journal_name
J Cell Scijournal_title
Journal of cell scienceauthors
Dimitrova DS,Gilbert DMsubject
Has Abstractpub_date
1998-10-01 00:00:00pages
2989-98eissn
0021-9533issn
1477-9137journal_volume
111 ( Pt 19)pub_type
杂志文章abstract::Endothelial integrity relies on a mechanical crosstalk between intercellular and cell-matrix interactions. This crosstalk is compromised in hemorrhagic vascular lesions of patients carrying loss-of-function mutations in cerebral cavernous malformation (CCM) genes. RhoA/ROCK-dependent cytoskeletal remodeling is central...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:10.1242/jcs.216093
更新日期:2018-08-13 00:00:00
abstract::Myofibroblasts, characterised by high expression of alpha-smooth muscle actin (alpha-SMA), are important and transient cells in normal wound healing but are found in increased number in various pathological conditions of the lung including asthma and pulmonary fibrosis. The mechanisms that regulate the myofibroblast p...
journal_title:Journal of cell science
pub_type: 杂志文章
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abstract::The large GTPase dynamin, long known for its role in endocytosis, has most recently been implicated as a facilitator of cell migration and invasion. Recent observations link dynamin to the cycle of membrane expansion and retraction essential for cell motility. Its role in actin polymerization, membrane deformation and...
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journal_title:Journal of cell science
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更新日期:2002-03-01 00:00:00
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journal_title:Journal of cell science
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journal_title:Journal of cell science
pub_type: 杂志文章
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pub_type: 杂志文章,评审
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更新日期:2018-04-09 00:00:00
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journal_title:Journal of cell science
pub_type: 杂志文章
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journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1997-01-01 00:00:00
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journal_title:Journal of cell science
pub_type: 杂志文章
doi:
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journal_title:Journal of cell science
pub_type: 杂志文章
doi:10.1242/jcs.129031
更新日期:2014-03-01 00:00:00
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journal_title:Journal of cell science
pub_type: 杂志文章
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更新日期:2015-02-01 00:00:00
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journal_title:Journal of cell science
pub_type: 杂志文章
doi:10.1242/jcs.116996
更新日期:2013-03-15 00:00:00
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journal_title:Journal of cell science
pub_type: 杂志文章,评审
doi:10.1242/jcs.01232
更新日期:2004-05-15 00:00:00
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journal_title:Journal of cell science
pub_type: 杂志文章
doi:10.1242/jcs.089672
更新日期:2011-11-01 00:00:00
abstract::Protrusion formation is the first step that precedes cell movement of motile cells. Spatial control of actin polymerization is necessary to achieve directional protrusion during cell migration. Here we show that the spatial coordinators p190RhoGEF and p190RhoGAP regulate actin polymerization during leading edge protru...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:10.1242/jcs.123547
更新日期:2013-08-01 00:00:00
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journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-11-01 00:00:00
abstract::Although many pathogenic copy number variations (CNVs) are associated with neuropsychiatric diseases, few of them have been functionally characterised. Here we report multiple schizophrenia cases with CNV abnormalities specific to unc-51-like kinase 4 (ULK4), a serine/threonine kinase gene. Deletions spanning exons 21...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:10.1242/jcs.137604
更新日期:2014-02-01 00:00:00
abstract::Dynamin-related GTPase proteins (DRPs) are main players in membrane remodelling. Conserved DRPs called mitofusins (Mfn1/Mfn2/Fzo1) mediate the fusion of mitochondrial outer membranes (OM). OM fusion depends on self-assembly and GTPase activity of mitofusins as well as on two other proteins, Ugo1 and Mdm30. Here, we de...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:10.1242/jcs.073080
更新日期:2011-04-01 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::Normal human foreskin keratinocytes (HFKs) and transformed HFKs (FEPE1L-8 cells) generated by the introduction of cloned human papillomavirus type 16 sequences were compared for the expression and function of a family of adhesion receptors termed integrins. Initially, cells were examined in conventional monolayer cult...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1992-11-01 00:00:00
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journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1994-06-01 00:00:00
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journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1998-12-01 00:00:00
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journal_title:Journal of cell science
pub_type: 杂志文章
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更新日期:2011-04-01 00:00:00
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journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1997-09-01 00:00:00
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journal_title:Journal of cell science
pub_type: 杂志文章
doi:
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journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1996-12-01 00:00:00
abstract::The Arabidopsis thaliana ASY1 gene is essential for homologous chromosome synapsis. Antibodies specific to Asy1 protein and its homologue BoAsy1 from the related crop species Brassica oleracea have been used to investigate the temporal expression and localization of the protein in both species. Asy1 is initially detec...
journal_title:Journal of cell science
pub_type: 杂志文章
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更新日期:2002-09-15 00:00:00
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journal_title:Journal of cell science
pub_type: 杂志文章
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更新日期:2017-04-01 00:00:00
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journal_title:Journal of cell science
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