X-ray induced sex-chromosome loss, when ring-X chromosome males are irradiated and mated to females carrying mei-9, mei-41 or mei-218

Abstract

Radiation damage induced in the sperm nucleus is repaired after this nucleus has enteredj the oocyte. The yield of induced genetic damage is known to be dependent on maternal genotype and can also be modified by treatment of the females with metabolic inhibitors. The experiments reported here were designed to find out whether a more specific analysis of the interaction between male gamate and oocyte cytoplasm can be carried out using mutants that are known to affect repair processes. Males carrying ring-X chromosomes were exposed to X-ray doses up to 1000 R and mated to females homozygous for a repair-deficient mutant. The mutants used were mei-9 9, mei-9 L1, mei-41 A10, and mei-41 D5. In addition a yellow ( y) X chromosome was used as a control and an attempt was made to obtain data using mei-218 15, a mutant at a locus not thought to affect repair. With mei-9 mutants there is an enhancement of the spontaneous and induced rates of paternal sex-chromosome loss. The mei-41 mutants did not affect the rates of paternal sex-chromosome loss. Mei-218 females were difficult to work with because they gave very few progeny. From these data it can be argued that repair-deficient mutants will indeed be useful for an analysis of the fixation of radiation-induced genetic damage.