DNA Distribution in Spermatid Nuclei of Normal and Segregation Distorter Males of DROSOPHILA MELANOGASTER.

Using the DNA-specific dye BAO [2,5-bis-(4'-aminophenyl-(1')]-1,3,4-oxadiazol), we have examined spermiogenesis in wild-type males of Drosophila melanogaster and in males carrying various combinations of the Sd and Rsp mutations involved in segregation distortion. Wild-type strains, even those newly collected from nature, are heterogeneous with respect to the incidence of spermiogenic abnormalities, principally in having a variable number of spermatid nuclei per cyst that fail to undergo complete elongation. Among segregation distorter males, Rsp/Rsp homozygotes have the greatest incidence of nuclear nonelongation or incomplete elongation, Rsp/Rsp( +) heterozygotes are intermediate, while Rsp(+)/ Rsp(+) homozygotes have the least amount of abnormality. Indeed, Sd Rsp(+)/Sd(+)Rsp(+) males have significantly fewer spermiogenic aberrations than do wild-type strains.