title: Photophobe (Ppb), a Drosophila mutant with a reversed sign of phototaxis; the mutation shows an allele-specific interaction with sevenless.
abstract: We have isolated a dominant behavioral mutation, Photophobe (Ppb), on the second chromosome of Drosophila melanogaster. Although wild-type flies are attracted towards green light, flies homozygous for the Ppb mutation avoid it over an intensity range of six logarithms. Ppb interacts in a dominant way with mutations in the sevenless (sev) gene, an X-chromosomal gene necessary for photoreceptor cell 7 differentiation in the Drosophila retina. Specific alleles of sev alter the Ppb behavioral phenotype; of eight sev alleles tested, two alleles enhanced the negative phototaxis of Ppb, whereas six alleles had the opposite effect. In no mutant combination of Ppb and sev was photoreceptor cell 7 restored. These data show that the sev gene, in addition to its role in the differentiation of photoreceptor cell 7, plays a role along with Ppb in a common visual information-processing pathway.
mesh_terms: D000483:Alleles; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D004331:Drosophila melanogaster / Q000235:genetics*; D005796:Genes; D005799:Genes, Dominant; D008027:Light; D009154:Mutation