Title: CHROMOSOMAL TRANSLOCATIONS GENERATED BY BETWEEN REPEATED YEAST GENES HIGH-FREQUENCY MEIOTIC RECOMBINATION
Abstract:We have examined meiotic and mitotic recombination between repeated genes on nonhomologous chromosomes in the yeast Saccharomyces cerevisiae. The results of these experiments can be summarized in thre...We have examined meiotic and mitotic recombination between repeated genes on nonhomologous chromosomes in the yeast Saccharomyces cerevisiae. The results of these experiments can be summarized in three statements. First, gene conversion events between repeats on nonhomologous chromosomes occur frequently in meiosis. The frequency of such conversion events is only 17-fold less than the analogous frequency of conversion between genes at allelic positions on homologous chromosomes. Second, meiotic and mitotic conversion events between repeated genes on nonhomologous chromosomes are associated with reciprocal recombination to the same extent as conversion between allelic sequences. The reciprocal exchanges between the repeated genes result in chromosomal translocations. Finally, recombination between repeated genes on nonhomologous chromosomes occurs much more frequently in meiosis than in mitosis. ECOMBINATION in eukaryotic organisms occurs in mitosis and meiosis R and may be either a reciprocal or nonreciprocal event. Reciprocal recombination changes the linkage relationships of genes along a chromosome and is the basis of genetic mapping. In those organisms in which all four products of a single meiotic division can be analyzed, nonreciprocal recombination or gene conversion is signaled by a 3:l segregation pattern of allelic sequences instead of the normal 2:2 segregation pattern. In fungi, reciprocal and nonreciprocal recombination are associated with one another so that, on the average, a gene conversion event at a given locus is accompanied by a reciprocal exchange event approximately half of the time (reviewed by ORR-WEAVER and SZOSTAK 1985). These conversion-associated reciprocal exchanges are usually detected by examining genetic markers that flank the site of the conversion event. The association of reciprocal and nonreciprocal recombination has been interpreted to mean that the two processes are mechanistically related to one another, and this notion has been incorporated into all current models of genetic recombination (MESELSON and RADDING 1975; SZOSTAK et al. 1983). Although models differ in the method of initiating a recombination event, allRead More
Publication Year: 1986
Publication Date: 1986-01-01
Language: en
Type: article
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