The Effects of Heterologous Rearrangements on Inter-locus and Intra-locus Recombination in Drosophila Melanogaster.

relationship of a recombinational event within a gene and crossing over T?etween linked ger,es has been explored by many investigators in recent years. Attempts have been made to discover whether a single exchange-mechanism exists to produce both inter-locus and intra-locus recombination. In several instances (for review see FREESE 1957; NELSON 1962), results have been obtained which indicate that separate exchange mechanisms are at work producing the two types of recombination. The work of PRITCHARD (1960), and DORN and BURDICK ( 1962), however, supports a single exchange-mechanism theory. These investigations were made using diverse genetic organisms and the final solution to this paradox may show that some organisms employ two or more exchange mechanisms while others exhibit only one such recombinational mode. To date the resolution of the minia ture-dusky complex in Drosophila melanogaster has, with a few reservations, yielded results which seem best interpreted by assuming that a single mechanism exists both within the complex and between it and other linked genic sites. This study was conducted to obtain further information concerning the mode of interand intra-genic recombination in the region of the X chromosome where the miniature-dusky complex is located. To do this, we have employed the widely known if not well explained interchromosomal crossing over effect exerted by heterologous structural rearrangements carried heterozygously in the genetic background.