Position effects in ectopic and allelic mitotic recombination in Saccharomyces cerevisiae. 1989

M Lichten, and J E Haber
Laboratory of Biochemistry, National Cancer Institute, Bethesda, Maryland 20892.

We have examined the role that genomic location plays in mitotic intragenic recombination. Mutant alleles of the LEU2 gene were inserted at five locations in the yeast genome. Diploid and haploid strains containing various combinations of these inserts were used to examine both allelic recombination (between sequences at the same position on parental homologs) and ectopic recombination (between sequences at nonallelic locations). Chromosomal location had little effect on mitotic allelic recombination. The rate of recombination to LEU2 at five different loci varied less than threefold. This finding contrasts with previous observations of strong position effects in meiosis; frequencies of meiotic recombination at the same five loci differ by about a factor of forty. Mitotic recombination between dispersed copies of leu2 displayed strong position effects. Copies of leu2 located approximately 20 kb apart on the same chromosome recombined at rates 6-13-fold higher than those observed for allelic copies of leu2. leu2 sequences located on nonhomologous chromosomes or at distant loci on the same chromosome recombined at rates similar to those observed for allelic copies. We suggest that, during mitosis, parental homologs interact with each other no more frequently than do nonhomologous chromosomes.

UI MeSH Term Description Entries
D008938 Mitosis A type of CELL NUCLEUS division by means of which the two daughter nuclei normally receive identical complements of the number of CHROMOSOMES of the somatic cells of the species. M Phase, Mitotic,Mitotic M Phase,M Phases, Mitotic,Mitoses,Mitotic M Phases,Phase, Mitotic M,Phases, Mitotic M
D009154 Mutation Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations. Mutations
D011995 Recombination, Genetic Production of new arrangements of DNA by various mechanisms such as assortment and segregation, CROSSING OVER; GENE CONVERSION; GENETIC TRANSFORMATION; GENETIC CONJUGATION; GENETIC TRANSDUCTION; or mixed infection of viruses. Genetic Recombination,Recombination,Genetic Recombinations,Recombinations,Recombinations, Genetic
D003434 Crossing Over, Genetic The reciprocal exchange of segments at corresponding positions along pairs of homologous CHROMOSOMES by symmetrical breakage and crosswise rejoining forming cross-over sites (HOLLIDAY JUNCTIONS) that are resolved during CHROMOSOME SEGREGATION. Crossing-over typically occurs during MEIOSIS but it may also occur in the absence of meiosis, for example, with bacterial chromosomes, organelle chromosomes, or somatic cell nuclear chromosomes. Crossing Over,Crossing-Over, Genetic,Crossing Overs,Genetic Crossing Over,Genetic Crossing-Over
D004171 Diploidy The chromosomal constitution of cells, in which each type of CHROMOSOME is represented twice. Symbol: 2N or 2X. Diploid,Diploid Cell,Cell, Diploid,Cells, Diploid,Diploid Cells,Diploidies,Diploids
D005800 Genes, Fungal The functional hereditary units of FUNGI. Fungal Genes,Fungal Gene,Gene, Fungal
D006238 Haploidy The chromosomal constitution of cells, in which each type of CHROMOSOME is represented once. Symbol: N. Haploid,Haploid Cell,Cell, Haploid,Cells, Haploid,Haploid Cells,Haploidies,Haploids
D000483 Alleles Variant forms of the same gene, occupying the same locus on homologous CHROMOSOMES, and governing the variants in production of the same gene product. Allelomorphs,Allele,Allelomorph
D012441 Saccharomyces cerevisiae A species of the genus SACCHAROMYCES, family Saccharomycetaceae, order Saccharomycetales, known as "baker's" or "brewer's" yeast. The dried form is used as a dietary supplement. Baker's Yeast,Brewer's Yeast,Candida robusta,S. cerevisiae,Saccharomyces capensis,Saccharomyces italicus,Saccharomyces oviformis,Saccharomyces uvarum var. melibiosus,Yeast, Baker's,Yeast, Brewer's,Baker Yeast,S cerevisiae,Baker's Yeasts,Yeast, Baker
D015825 Chromosomes, Fungal Structures within the nucleus of fungal cells consisting of or containing DNA, which carry genetic information essential to the cell. Chromosome, Fungal,Fungal Chromosome,Fungal Chromosomes

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