Lu B, Liu W, Guo F, Guo A
State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
Genes Brain Behav. 2008 Oct;7(7):730-9. doi: 10.1111/j.1601-183X.2008.00411.x. Epub 2008 Jun 2.
The relationship between light and the circadian system has long been a matter of discussion. Many studies have focused on entrainment of light with the internal biological clock. Light also functions as an environmental stimulus that affects the physiology and behaviour of animals directly. In this study, we used light as an unexpected stimulus for flies at different circadian times. We found that wildtype flies showed circadian changes in light-induced locomotion responses. Elevation of locomotor activity by light occurred during the subjective night, and performance in response to light pulses declined to trough during the subjective day. Moreover, arrhythmic mutants lost the rhythm of locomotion responses to light, with promotion of activity by light in timeless(01)mutants and inhibition of activity by light in Clock(ar)mutants. However, neither ablation of central oscillators nor disturbance of the functional clock inside compound eyes was sufficient to disrupt the rhythm of light responses. We show that, compound eyes, which have been identified as the control point for normal masking (promotion of activity by light), are sufficient but not necessary for paradoxical masking (suppression of activity by light) under high light intensity. This, taken together with the clear difference of light responses in wildtype flies, suggests that two different masking mechanisms may underlie the circadian modulation of light-induced locomotion responses.
光与昼夜节律系统之间的关系长期以来一直是一个讨论的话题。许多研究都集中在光与内部生物钟的同步上。光还作为一种环境刺激直接影响动物的生理和行为。在本研究中，我们在不同的昼夜节律时间将光作为果蝇的意外刺激。我们发现野生型果蝇在光诱导的运动反应中表现出昼夜节律变化。光引起的运动活动增加发生在主观夜间，而对光脉冲的反应在主观白天降至低谷。此外，无节律突变体失去了对光的运动反应节律，在timeless(01)突变体中光促进活动，而在Clock(ar)突变体中光抑制活动。然而，无论是中枢振荡器的消融还是复眼中功能时钟的干扰都不足以破坏光反应的节律。我们表明，复眼已被确定为正常掩蔽（光促进活动）的控制点，在高光强度下对于反常掩蔽（光抑制活动）是足够的但不是必需的。这与野生型果蝇光反应的明显差异一起表明，两种不同的掩蔽机制可能是光诱导运动反应昼夜调节的基础。
