The isolation of biological rhythm mutations on the autosomes of Drosophila melanogaster.

A selection for autosomal circadian rhythm variants in Drosophila melanogaster resulted in the isolation of 3 new mutants, all of which display an abnormal synchronization of daily rhythms to entraining environmental cycles. In populations of phase-angle-2 (psi-2) and phase-angle-3 (psi-3) mutants, daily peaks of adult emergence are hours earlier than normal when the strains are entrained to cycles of either light and dark or high and low temperature. Like an early-emerging strain previously isolated in Drosophila pseudoobscura, the psi strains have slightly lengthened periods for the circadian rhythm in adult emergence. In addition, psi-2 brings about an abnormal synchronization of locomotor activity to light-dark cycles and lengthens periods for the activity rhythm. The emergence of adults in a third mutant strain designated gat is poorly synchronized becoming aperiodic in conditions of continuous darkness and constant temperature.