Recombination in the X-chromosome in hybrid females with and without a marked centromere from three inbred lines of Drosophila melanogaster.

Abstract

Hybrid females of three inbred lines of Drosophila melanogaster, with and without BSYL attached to the marker line centromere, were produced by reciprocal crosses. The recombination frequency was scored along the X-chromosome. In XX females one inter-line cross showed differences between reciprocal crosses in all regions examined, indicating maternal influence, while the other inter- and intra-line crosses showed no obvious effects. Only the inter-line cross manifesting effects in XX females showed maternal effects in XX-YL females. Of special interest was the brood pattern of the f-centromere region. Concerning the effects of the YL arm, the recombination in the y-cx region seemed to increase in early broods and decrease in late broods. In the v-f region there were decreases in both early and late broods, while in the cx-v region the YL-effects were varying. These results are discussed in the light of recombination in XXY females from former tests, and the brood pattern of the f-centromere is compared with findings of higher frequencies of non-disjunction in early broods compared with later ones. The spatial location of the chromosomes in the nucleus during meiosis is discussed as a possible explanation for the discrepancy between crosses.