Genetics. Published Articles Ahead of Print: June 18, 2008, Copyright © 2008
doi:10.1534/genetics.107.083493


A more recent version of this article appeared on July 1, 2008.

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Meiotic Recombination at Chromosome Ends in Saccharomyces cerevisiae

Arnold B. Barton 1, Michael Pekosz 1, Rohini S. Kurvathi 1 and David B. Kaback 1*

1 UMDNJ-New Jersey Medical School

* To whom correspondence should be addressed. E-mail: kaback{at}umdnj.edu.

Submitted on October 17, 2007
Revised on November 28, 2007
Accepted on 12 May 2008


Abstract

Meiotic reciprocal recombination (crossing over) was examined in the outermost 60-80 kb of almost all Saccharomyces cerevisiae chromosomes. These sequences included both repetitive gene poor subtelomeric heterochromatin-like regions and their adjacent unique gene rich euchromatin-like regions. Subtelomeric sequences underwent very little crossing over, exhibiting ~2-3-fold fewer crossovers per kb of DNA than the genomic average. Surprisingly, the adjacent euchromatic regions underwent crossing over at twice the average genomic rate and contained at least 9 new recombination "hot spots". These results prompted an analysis of existing genetic mapping data which showed that meiotic reciprocal recombination rates were on average greater near chromosome ends exclusive of the subtelomeres. Thus, the distribution of crossovers in S. cerevisiae appears to resemble that found in several higher eukaryotes where the outermost chromosomal regions show increased crossing over.

Key Words: crossing over, heterochromatin, meiosis, subtelomeres, telomeres