Co-Authors:
Goldway, M., Department of Genetics, Hebrew University of Jerusalem, Jerusalem 91904, Israel
Sherman, A., Department of Genetics, Hebrew University of Jerusalem, Jerusalem 91904, Israel
Zenvirth, D., Department of Genetics, Hebrew University of Jerusalem, Jerusalem 91904, Israel
Arbel, T., Department of Genetics, Hebrew University of Jerusalem, Jerusalem 91904, Israel
Simchen, G., Department of Genetics, Hebrew University of Jerusalem, Jerusalem 91904, Israel
Abstract:
A multicopy plasmid was isolated from a yeast genomic library, whose presence resulted in a twofold increase in meiotic nondisjunction of chromosome III. The plasmid contains a 7.5-kb insert from the middle of the right arm of chromosome III, including the gene THR4. Using chromosomal fragments derived from chromosome III, we determined that the cloned region caused a significant, specific, cis-acting increase in chromosome III nondisjunction in the first meiotic division. The plasmid containing this segment exhibited high spontaneous meiotic integration into chromosome III (in 2.4% of the normal meiotic divisions) and a sixfold increase (15.5%) in integration in nondisjunctant meioses. Genetic analysis of the cloned region revealed that it contains a 'hot spot' for meiotic recombination. In DNA of rad50S mutant cells, a strong meiosis-induced double strand break (DSB) signal was detected in this region. We discuss the possible relationships between meiosis-induced DSBs, recombination and chromosome disjunction, and propose that recombinational hot spots may be 'pairing sites' for homologous chromosomes in meiosis.