Document Detail

Dinoflagellate chromosome behaviour during stages of replication.
MedLine Citation:
PMID:  10943399     Owner:  NLM     Status:  MEDLINE    
In most dinoflagellate species, chromosomes are characterized by an almost continuous condensation of the nucleofilaments throughout the cell cycle and the absence of longitudinal differentiation as Q, G, or C banding. Their supercoiled architecture is maintained by divalent cations and structural RNAs. Their chromatin is devoid of histones and nucleosomes and their DNA composition is distinctive: in several species, more than 60% of thymines are replaced by a rare base, hydroxymethyluracil. We report here an immunofluorescence (conventional and confocal laser scanning microscopy, CLSM) and immunogold transmission electron microscopy (TEM) analysis of some stages of the early replication process in Prorocentrum micans dinoflagellate cells, after long pulse incorporation (3, 6 or 9 days) with 50 micrograms/ml bromodeoxyuridine (BrdU) in the presence of 5-fluoro-2'-deoxyuridine (FUdR) and BrdU antibody technique (BAT) detection. The large DNA content (45 pg per nucleus) of P. micans cells is compacted on 100 chromosomes, 10 microns in length. In early S-phase, DNA replication sites are revealed as fluorescent domains organized in clusters, which appear in the periphery of the nucleus unlike other eukaryotes. In late S-phase, the number of labelled clusters increased; helically distributed, they did not appear synchronously in the whole chromosome. Under TEM, spherical domains of equivalent diameter appeared located all along the chromosomes after 6 days BrdU pulse. Replication occurs, but in our experimental conditions, segregation of daughter chromosomes was never observed. The blockade of the cell cycle after BrdU incorporation intervening just before the segregation of daughter chromosomes is discussed.
M O Soyer-Gobillard; B Gillet; M L Géraud; Y Bhaud
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  International microbiology : the official journal of the Spanish Society for Microbiology     Volume:  2     ISSN:  1139-6709     ISO Abbreviation:  Int. Microbiol.     Publication Date:  1999 Jun 
Date Detail:
Created Date:  2000-10-05     Completed Date:  2000-10-05     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9816585     Medline TA:  Int Microbiol     Country:  SPAIN    
Other Details:
Languages:  eng     Pagination:  93-102     Citation Subset:  IM    
Observatoire Océanologique de Banyuls, Laboratoire Arago, Université Paris 6, Banyuls-sur-mer, France.
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MeSH Terms
Bromodeoxyuridine / analysis
Cell Cycle
Chromosomes / physiology*,  ultrastructure
DNA Replication
DNA, Protozoan / genetics
Dinoflagellida / cytology,  genetics*,  ultrastructure
Microfilaments / physiology
Microscopy, Confocal
Microscopy, Electron
Microscopy, Fluorescence
Reg. No./Substance:
0/DNA, Protozoan; 59-14-3/Bromodeoxyuridine

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