Document Detail

The transition from conjugal development to the first vegetative cell division is dependent on RAD51 expression in the ciliate Tetrahymena thermophila.
MedLine Citation:
PMID:  11290715     Owner:  NLM     Status:  MEDLINE    
Rad51p, the eukaryotic homolog of the prokaryotic recA protein, catalyzes strand exchange between single- and double-stranded DNA and is involved in both genetic recombination and double-strand break repair in the ciliate Tetrahymena thermophila. We have previously shown that disruption of the Tetrahymena RAD51 somatic macronuclear locus leads to defective germline micronuclear division and that conjugation of two somatic rad51 null strains results in an early meiotic arrest. We have constructed Tetrahymena strains that are capable of RAD51 expression from their parental macronuclei and are homozygous, rad51 nulls in their germline micronuclei. These rad51 null heterokaryons complete all of the early and middle stages of conjugation, including meiosis, haploid nuclear exchange, zygotic fusion, and the programmed chromosome fragmentations, sequence eliminations, and rDNA amplification that occur during macronuclear development. However, the rad51 null progeny fail to initiate the first vegetative cell division following conjugal development. Coincident with the developmental arrest is a disproportionate amplification of rDNA, despite the maintenance of normal total DNA content in the developing macronuclei. Fusion of arrested rad51 null exconjugants to wild-type cells is sufficient to overcome the arrest. Cells rescued by cytoplasmic fusion continue to divide, eventually recapitulating the micronuclear mitotic defects described previously for rad51 somatic nulls.
T C Marsh; E S Cole; D P Romero
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Genetics     Volume:  157     ISSN:  0016-6731     ISO Abbreviation:  Genetics     Publication Date:  2001 Apr 
Date Detail:
Created Date:  2001-04-06     Completed Date:  2001-07-12     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0374636     Medline TA:  Genetics     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1591-8     Citation Subset:  IM    
Department of Pharmacology, Medical School, University of Minnesota, Minneapolis, Minnesota 55455, USA.
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MeSH Terms
Cell Division
DNA, Ribosomal
DNA-Binding Proteins / genetics,  physiology*
Gene Expression
Genome, Protozoan
Rad51 Recombinase
Tetrahymena thermophila / growth & development
Grant Support
Reg. No./Substance:
0/DNA, Ribosomal; 0/DNA-Binding Proteins; EC 2.7.7.-/Rad51 Recombinase

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