The first gene shown to control a circadian clock (q.v.). Mutations at the per locus alter the rhythmicity of eclosion and of adult locomotor activity. This sex-linked gene has been cloned and sequenced in D. melanogaster, pseudoobscura, and virilis. Null mutants (per0) show no rhythmicity of eclosion or locomotor activity. Missense mutations shorten (perS) or lengthen (perL) both rhythms. The per+ gene is expressed in the normal adult nervous system, and it encodes a PER protein containing about 1,200 amino acids. The protein is present at extremely low levels, and it does not contain structural motifs of the sort that characterize DNA-binding domains, signal factors, or membrane-spanning domains. The gene also modulates the interpulse intervals during courtship “songs.” These are generated by the extension and vibration of the males' wings, and the songs enhance the females' mating behavior. The songs are species-specific, and per has been shown to contain species-specific song instructions by introducing a cloned copy of per from D. simulans into the genome of a D. melanogaster per0 mutant. See Chronology, 1971, Konopka and Benzer; 1984, Bargiello and Young; 1991, Wheeler et al.; frequency.
Subjects: Genetics and Genomics.