Behavioral and molecular genetic analysis of the Drosophilano-on-transient A locus

Mutations at the nonA locus affect vision, courtship song and viability in the adult animal.; In this thesis, I present evidence that the dissonance mutation is an allele of the nonA locus. This is demonstrated by genetic complementation analysis and transformation rescue of {dollar}nonAsp{lcub}diss{rcub}{dollar} with a fragment of genomic DNA containing the nonA open reading frame. In addition, I show that the behavioral defects associated with this allele are robustly rescued by an inducible transformant expressing the nonA ORF.; As a participant in a collaboration, I show that the nonA null mutant generated by Stanewsky et al. (1993) is blind and exhibits a severe deficit in courtship song.; By immunohistochemical studies, I have found that the expression of the NONA protein in the wild-type fly is widespread, and is localized to the nucleus in many tissues throughout development and the adult stage.; In chapter one, I report the homology of NONA to a large family of proteins containing RNA recognition motifs (RRMs), which suggested that nonA has a pre-mRNA processing function. In the final chapter, the NONA protein is shown to contain a more extensive region of homology to four recently identified proteins which includes a charged region adjacent to the RRM domains.; I have demonstrated by molecular analysis that three nonA alleles contain point mutations within this conserved region. Site-directed mutagenesis of the RNPI and II domains of the RRMs, and of amino acid 548 of the charged region, which is mutated in the {dollar}nonAsp{lcub}diss{rcub}{dollar} allele, was carried out to determine its effects on behavior. All but one transgenic type containing point mutations in the nonA null genetic background produced full length protein. Mutations in RRM1 and the charged region exhibited effects on vision, courtship song and viability.