THE RPA (RECEPTOR POTENTIAL ABSENT) VISUAL MUTANT OF THE BLOWFLY (CALLIPHORA-ERYTHROCEPHALA) IS DEFICIENT IN PHOSPHOLIPASE-C IN THE EYE

The rpa (receptor potential absent) mutation of the blowfly, Calliphor a erythrocephala, reduces the light-evoked responses of photoreceptor cells and renders the fly blind. This phenotype is similar to the phen otype caused by norpA mutations in Drosophila which have been shown to occur within a gene encoding phospholipase C. In Western blots, norpA antiserum stains a protein in homogenates of wild-type Calliphora eye and head that is similar in molecular weight to the norpA protein. Ve ry little staining of this protein is observed in similar homogenates of rpa mutant. Moreover, norpA antiserum strongly stains retina in imm unohistochemical assays of wild-type adult head, but not in rpa mutant . Furthermore, eyes of rpa mutant have a reduced amount of phospholipa se C activity compared to eye of wild-type Calliphora. These data sugg est that the rpa mutation occurs in a phospholipase C gene of the blow fly that is homologous to the norpA gene of Drosophila.