22.5hr clock mutant.

The mean period of locomotor activity is shorter than wild-type (average value is 22.8 +/- 0.1 hours).

Short cycle duration, the evening peak of activity is shifted to an earlier time than wild type.

The activity rhythm period of per^Clk/Y flies is lengthened by CkIIβ^And, by 1.1 hours.

The period of the free-running locomotor activity rhythm is shortened to approximately 22.5 hours in hemizygous males. The periodicity is slightly temperature sensitive, becoming shorter over a range of 17-28^oC. The phase response curve is similarly shortened. Heterozygous females have an periodicity intermediate between that of hemizygous males and wild-type. Eclosion peaks of per^Clk cultures are separated by only 22.5 hours. per⁰¹/per^Clk flies have statistically indistinguishable rhythms from per^Clk/per⁺ flies. Male per^Clk flies have an essentially normal courtship song.

1.5 hour shortening of the circadian rhythms of locomotor activity. Hemizygous males have essentially normal one minute song rhythm.

The normal 24 hour period of the circadian rhythms of adult locomotor activity and of eclosion are shortened by approximately 1.5 hours. Clk/+ heterozygotes have a period phenotype intermediate between wild-type and mutant homozygotes. The period of the phase-resetting response of the activity rhythm is shortened by 1-2 hours per cycle; adults entrain well to 12 hour light: twelve hour dark cycles, but evening peak of locomotor activity is advanced relative to wild-type; courtship song rhythms of mutant males have essentially normal one-minute periods. Temperature compensation of circadian period is normal (Q₁₀ approximately equal to 1.0), in tests of locomotor activity rhythms.