A genetic and molecular analysis of two Drosophila meiotic mutants encoding kinesin-like proteins

Abstract

The nod, no distributive disjunction and ncd, non-claret disjunctional are female-specific, recessive meiotic mutations in Drosophila melanogaster. Mutations at either locus show high frequencies of chromosome nondisjunction at meiosis I and both loci have been shown to encode kinesin-like proteins. Unlike the ncd mutation, which affects all chromosome pairs, nod only affects disjunction of nonexchange chromosomes. This report describes experiments that seek, through second-site noncomplementation analysis and in situ hybridization experiments to define the relationship between these genes.;Although both the nod and ncd mutations are fully recessive, females doubly heterozygous for nod and ncd mutations were found to have levels of X and fourth chromosome nondisjunction 6-to-35 fold above those observed in control females. We infer that ncd is a dominant enhancer of nod. In situ hybridization data reveal that these transcripts have largely overlapping expression patterns during oogenesis. We propose that the relationship between the nod and ncd kinesin-like proteins is not one of direct structural interaction, but rather one defined by the temporal nature of the meiotic process.