Identification and Characterization of The Photorecetor of Insect Circadian Clock

对正常果蝇和突变果蝇在不同光照条件下的运动活动进行了研究。正常果蝇在主观夜间给予不同强度的短光闪光，此时果蝇的昼夜运动活动降至最低水平。强光引起(1)光刺激时运动活动增加，(2)由于闪光的夹带，导致昼夜运动活动的相移。而低强度的闪光只在刺激时引起运动活动的增加，而不会引起昼夜活动的相移。眼睛突变，如正弦眼球或眼睛缺失，其中总的复合眼的结构缺失正常果蝇的运动活动的解离和无眼突变体的直接光反应表明：(1)昼夜节律钟的光感受器(S)不是复眼；(2)运动活动的直接光反应仍受复眼的输入控制。无细胞突变体也表现出对闪光的正常相移，这表明眼球细胞不参与果蝇的光反应生物钟。虽然生物钟的光感受器的性质仍然不清楚，这项研究揭示了视觉系统的输入在不重置活动的情况下影响运动活动的存在。

Locomotor activity of the adult normal and mutant fruit flies Drosophila melanogaster was investigated under various lighting conditions.Normal flies were given a short light flash of various intensities during the subjective night when the circadian locomotor activity decreases to the minimum level.An intense light induced both (1) an increase of locomotor activity during the light stimulation and (2) a phase-shift of the circadian locomotor activities as a result of the entrainment by the light flash.Flashes of lower intensity, however, induced only the increase of locomotor activity during the stimulation without phase-shifting the circadian activity.Eye mutants, like sine oculis or eye-missing where the structures of the total compound eyes are missing, did not show the direct light response to the flash while they showed almost normal phase-shift of the circadian activity.The dissociation of the locomotor activities in the normal flies and the absence of the direct light response in the eye-less mutants suggest (1) that the photoreceptor (s) of the circadian clock is not the compound eyes and (2) that the direct light response of the locomotor activity is nevertheless controlled by the input from the compound eyes.The ocelli-less mutants also showed a normal phase-shift in response to the light flash suggesting that the ocelli are not involved in the photoresponse of the circadian clock.While the nature of the photoreceptor of the circadian clock still remained unclear, this study has revealed the presence an input from the visual system affecting the locomotor activity without resetting the activity.