Circadian Rhythm of Dark-fly

Abstract

Locomotor activity rhythms of Dark-stock flies of Drosophila melanogaster kept in complete darkness for 700–1,340 generations were examined. The activity of flies was recorded under the conditions of continuous darkness and of light–dark cycling. The activity rhythm of the experimental dark stock flies observed in continuous darkness was not weakened at 1,340 generations or at 700–900 generations. The degree of diurnality, measured by the ratio of daytime activity to the total activity per day under light–dark cycling, did not differ between the Dark-fly of 700–900 generations and the control fly subjected to normal daylight conditions for the same number of generations. Dark-flies showed a slightly weaker depression of activity in the daytime than control flies did. The possibility of alteration of circadian rhythm in Dark-fly is discussed.