Distributive disjunction of authentic chromosomes in Saccharomyces cerevisiae
1991
Guacci, V. | Kaback, D.B.
Distributive disjunction is defined as the first division meiotic segregation of either nonhomologous chromosomes that lack homologs or homologous chromosomes thathave not recombined. To determine if chromosomes from the yeast Saccharomyces cerevisiaewere capable of distributive disjunction, we constructed a strain that was monosomic for both chromosome I and chromosome III and analyzed the meiotic segregation of the two monosomicchromosomes. In addition, we bisected chromosome I into two functional chromosome fragments,constructed strains that were monosomic for both chromosome fragments and examined meiotic segregation ofthe chromosome fragments in the monosomic strains. The two nonhomologous chromosomes orchromosome fragments appeared to segregate from each other in approximately 90% of the ascianalyzed, indicating that yeast chromosomes were capable of distributive disjunction. We alsoexamined the ability of a small nonhomologous centromere containing plasmid to participate in distributive disjunction with the two nonhomologous monosomic chromosomes. The plasmid appeared toefficiently participate with the two full length chromosomes suggesting that distributivedisjunction in yeast is not dependent on chromosome size. Thus, distributive disjunction in S. cerevisiaeappears to be different from Drosophila melanogaster where a different sized chromosome is excluded from distributive disjunction when two similar size nonhomologous chromosomes are present.
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