Studies on the sex specific lethals of Drosophila melanogaster. II. Further studies on a male specific lethal gene, maleless

Abstract

Effects of a second chromosome male specific lethal gene, maleless (mle), of Drosophila melanogaster were further studied. It was shown that, although no maternal effect was seen with respect to the male specific lethality, the lethal stage was influenced by whether parental females were homozygous or heterozygous for mle. Thus, in the former mle/mle males died mostly in the late third instar larval stage, while in the latter practically all males survived to the pupal stage. In the dying mle/mle male pupae complete differentiation of adult external head and thorax structures was often observed but that of abdominal structures was incomplete forming only a few segments in most cases. Imaginal discs from third instar mle/mle male larvae which were produced by mle/mle mothers and were destined to die as larvae were able to differentiate into adult structures upon transplantation into normal third instar larval hosts. A somewhat elaborated version of the previously presented hypothesis (Fukunaga, Tanaka and Oishi 1975) is discussed as to the possible presence of a class of sex specific lethals which are not related to the process of primary sex differentiation.