A genetic analysis of the<i>rudimentary</i>locus of<i>Drosophila melanogaster</i>

Abstract

SUMMARY A study of the structural and functional organization of the rudimentary ( r : 1–54·5) locus of Drosophila melanogaster has demonstrated that alleles of this gene reside in a number of recombinationally separable sites, and display a complex pattern of interallelic interaction. Data relating to interallelic interaction have been utilized to construct a linear complementation map consisting of 7 complementation units and 16 complementation groups. Comparison of the genetic fine structure map and the complementation map shows that the two maps are approximately co-linear. Totally non-complementing alleles reside at both ends of the fine structure map. The r locus is best interpreted by the model of a single cistron whose product affects several distinct developmental processes and whose alleles display a complex pattern of interallelic complementation. Intragenic recombination within the r locus is accompanied by the appearance of parental and recombinant flanking marker classes not expected on the basis of reciprocal recombination. Studies with half-tetrads demonstrate that intragenic recombination can occur either by gene conversion or by a reciprocal exchange mechanism. The pattern of organization seen at the r locus is similar to patterns of organization found in work with fungal genes.