COURTSHIP AND VISUAL DEFECTS OF CACOPHONY MUTANTS REVEAL FUNCTIONAL COMPLEXITY OF A CALCIUM-CHANNEL ALPHA-1 SUBUNIT IN DROSOPHILA

We show by molecular analysis of behavioral and physiological mutants that the Drosophila DmcalA calcium-channel alpha 1 subunit is encoded by the cacophony (cac) gene and that nightblind-A and lethal(l)L13 mut ations are allelic to cac with respect to an expanded array of behavio ral and physiological phenotypes associated with this gene. The cac(S) mutant, which exhibits defects in the patterning of courtship loveson g and a newly revealed but subtle abnormality in visual physiology, is mutated such that a highly conserved phenylalanine (in one of the qua si-homologous intrapolypeptide regions called IIIS6) is replaced by is oleucine. The cac(H18) mutant exhibits defects in visual physiology (i ncluding complete unresponsiveness to light in cel tain genetic combin ations) and visually mediated behaviors; this mutant (originally nbA(H 18)) has a stop codon in an alternative exon (within the cac ORF)I whi ch is differentially expressed in the eye. Analysis of the various cou rtship and visual phenotypes associated with this array of cac mutants demonstrates that DmcalA calcium channels mediate multiple, separable biological functions; these correlate in part with transcript diversi ty generated via alternative splicing.