ANALYSIS OF TEMPERATURE-SENSITIVE MUTANTS REVEALS NEW GENES INVOLVED IN THE COURTSHIP SONG OF DROSOPHILA

cacophony (cac), a mutation affecting the courtship song in Drosophila melanogaster is revealed to cause temperature-sensitive (TS) abnormal ities. When exposed to high temperatures (37 degrees), cac flies show frequent convulsions and pronounced locomotor defects. This TS phenoty pe seems consistent with the idea that cac is a mutation in a calcium- channel gene; it maps to the same X-chromosomal locus that encodes the polypeptide comprising the alpha-1 subunit of this membrane protein. Analysis of the courtship song of some TS physiological mutants showed that slowpoke mutations, which affect a calcium-activated potassium c hannel, cause severe song abnormalities. Certain additional TS mutants , in particular para(ts1) and nap(ts1), exhibit subtler song defects. The results therefore suggest that genes involved in ion-channel funct ion are a potential source of intraspecific genetic variation for song parameters, such as the number of cycles present in ''pulses'' of ton e or the rate at which pulses are produced by the male's courtship win g vibrations. The implications of these findings from the perspective of interspecific lovesong variations in Drosophila are discussed.