Mutant alleles of the meiotic locus,mei-9, differ in degree of effects on rod chromosome magnification and ring chromosome transmission inDrosophila

Abstract

SummaryTwo mutant alleles of the meiotic locus,mei-9, have been examined for their effect on magnification of a rodXbbchromosome and transmission of a ringXbbchromosome under magnifying conditions. Our results indicate that the effects of these two mutations are allele-specific:mei-9astrongly inhibits both rod chromosome magnification and ring chromosome loss under magnifying conditions, whilemei-9bhas a smaller inhibitory effect on rod chromosome magnification and on the transmission of ring chromosomes under magnifying conditions. These observations can be explained by a difference in leakiness between the two alleles. Our results demonstrate that mutants defective in excision repair and repair replication inhibit ribosomal gene magnification. This suggests that a component of the excision repair pathway is involved in the process of magnification.