Meiotic Gene Conversion in Yeast: Molecular and Experimental Perspectives

Fogel, Seymour; Mortimer, Robert; Lusnak, Karin

doi:10.1007/978-1-4612-5491-1_3

Cited by 26 publications

(15 citation statements)

References 88 publications

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“…In addition, Fogel et al found that meiotic conversion tracts were usually continuous. Although the results of most other studies in fungal systems are consistent with the conclusion that meiotic conversion tracts are generally less than 1 kb in length (summarized by Orr-Weaver and Szostak [29]), DiCaprio and Hastings (5) and Fogel et al (11) reported occasional coconversion of markers in different genes.…”

supporting

confidence: 75%

“…In all models, the structure formed during conversion is resolved into two chromosomes ( The distribution of gene conversion events, like the distribution of crossovers, is not uniform along the chromosome. The length of the conversion tracts was longer than expected on the basis of most previous genetic studies involving coconversion of mutant alleles within single genes (10), although there are two reports of conversion tracts that extended over large genetic distances (5,11). Although almost all of the observed conversion tracts were continuous (as in previous studies [10]), we found a few tracts in which a site that segregated 2:2 was flanked by sites that were segregating 3:1 or 1:3 (Fig.…”

Section: Constructionmentioning

confidence: 82%

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Expansions and contractions of the genetic map relative to the physical map of yeast chromosome III.

Symington¹,

Petes²

1988

Mol. Cell. Biol.

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To examine the relationship between genetic and physical chromosome maps, we constructed a diploid strain of the yeast Saccharomyces cerevisiae heterozygous for 12 restriction site mutations within a 23-kilobase (5-centimorgan) interval of chromosome m. Crossovers were not uniformly distributed along the chromosome, one interval containing significantly more and one interval significantly fewer crossovers than expected. One-third of these crossovers occurred within 6 kilobases of the centromere. Approximately half of the exchanges were associated with gene conversion events. The minimum length of gene conversion tracts varied from 4 base pairs to more than 12 kilobases, and these tracts were nonuniformly distributed along the chromosome. We conclude that the chromosomal sequence or structure has a dramatic effect on meiotic recombination.In general, one expects to find that the frequency of recombination between two genes should be proportional to the physical distance between the two markers. Deviations from this expectation have been observed, however, and are usually attributed to one of two factors: the proximity of chromosomal structural elements (such as the centromere) to the genetic interval, or the presence (or absence) of sequence-specific "hotspots" for recombination within the genetic interval.The clearest example of an effect of chromosome structure on recombination of adjacent sequences is the effect of the centromere on meiotic exchange in Drosophila melanogaster. The genetic map is contracted relative to the physical map at the centromere (6). Several experiments have indicated the possibility of a similar centromeric repression of meiotic exchange in fungi. First, in Aspergillus nidulans and Saccharomyces cerevisiae, there is relatively more mitotic than meiotic recombination near the centromere (23, 31). The second type of experiment concerned the physical analysis of cloned centromeric sequences of S. cerevisiae (3,8,13). Two short conserved sequences (8 and 25 base pairs [bp]) flanking an A+T-rich spacer of 70 to 100 bp are sufficient for centromere function. In some cases, the physical distance between a cloned centromere and a selectable gene was known, and therefore a correlation between genetic and physical distance near the centromere could be established. Although the ratio between centimorgans (cM) and kilobases (kb) for some of these centromeric regions was lower than the average for the genome (37), for others the ratio was about the same. A third type of experiment involved moving the centromere of yeast chromosome III to a new position within the same chromosome. In such yeast strains, Lambie and Roeder (20) found that meiotic recombination increased in an interval near the original position of the centromere, whereas recombination in the interval into which the centromere had been introduced decreased.In addition to effects of structural elements on recombination, there are sites that appear to stimulate homologous recombination locally (reviewed by Whitehouse (41]). For

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supporting

confidence: 75%

Section: Constructionmentioning

confidence: 82%

Expansions and contractions of the genetic map relative to the physical map of yeast chromosome III.

Symington¹,

Petes²

1988

Mol. Cell. Biol.

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“…A wild-type diploid un dergoes -90 crossovers (Olson 1991) and nearly twice as many strand exchange reactions unaccompanied by re ciprocal exchange (Fogel et al 1983) for a total of -260 events. The maximum number of sites of Dmcl local ization is 62 (Bishop 1994).…”

Section: Axial Associations May Be Sites Of Double-strand Break Procementioning

confidence: 99%

Roles for two RecA homologs in promoting meiotic chromosome synapsis.

Rockmill¹,

Sym²,

Scherthan³

et al. 1995

Genes Dev.

204

215

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Previous studies have shown that the RAD51 and DMCl genes of Saccharomyces cerevisiae encode homologs of the Escherichia coli RecA strand exchange enzyme. Results presented here demonstrate that the dmcl and radSl mutants undergo nearly complete chromosome synapsis, but synaptonemal complex formation is delayed substantially compared with wild type. In the zipl mutant, chromosomes are paired homologously, but not synapsed, and the protein backbones (axial elements] of each pair of chromosomes are connected intimately to each other at a few sites referred to herein as axial associations, dmcl zipl and radSl zipl double mutants assemble axial elements that are not obviously associated, demonstrating that the Dmcl and Rad51 proteins are required to establish or stabilize axial associations. We propose that axial associations serve to promote meiotic chromosome synapsis and that the absence of these associations accounts for the delayed and inefficient synapsis observed in dmcl and radSl strains. During meiosis in haploid yeast, chromosome synapsis takes place between nonhomologous chromosome segments. In a zipl haploid, axial associations are not apparent, suggesting that these associations depend on interactions between homologous sequences.

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“…In the budding yeast Saccharomyces cerevisiae over 200 interhomologue recombination events occur during meiotic prophase (Fogel et al 1983). Most or all of these recombination events involve a DNA double strand break (DSB) intermediate (Lichten & Goldman 1995).…”

Section: Introductionmentioning

confidence: 99%

High copy number suppression of the meiotic arrest caused by a dmc1 mutation: REC114 imposes an early recombination block and RAD54 promotes a DMC1‐independent DSB repair pathway

et al. 1999

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Background: DMC1, the meiosis-speci®c eukaryotic homologue of bacterial recA, is required for completion of meiotic recombination and cell cycle progression past prophase. In a dmc1 mutant, double strand break recombination intermediates accumulate and cells arrest in prophase. We isolated genes which, when present at high copy numbers, suppress the meiotic arrest phenotype conferred by dmc1 mutations.

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Meiotic Gene Conversion in Yeast: Molecular and Experimental Perspectives

Cited by 26 publications

References 88 publications

Expansions and contractions of the genetic map relative to the physical map of yeast chromosome III.

Expansions and contractions of the genetic map relative to the physical map of yeast chromosome III.

Roles for two RecA homologs in promoting meiotic chromosome synapsis.

High copy number suppression of the meiotic arrest caused by a dmc1 mutation: REC114 imposes an early recombination block and RAD54 promotes a DMC1‐independent DSB repair pathway

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