Institute of Zoology, University of Regensburg, Regensburg, Germany.
J Biol Rhythms. 2010 Dec;25(6):387-98. doi: 10.1177/0748730410381962.
The blue-light photoreceptive protein Cryptochrome (CRY) plays an important role in the light synchronization of the Drosophila circadian clock. Previously, we found that among the approximately 150 clock neurons, many but not all neurons express CRY. We speculated that the CRY-positive pacemaker neurons may be especially important for light entrainment, whereas the CRY-negative neurons may be important for other environmental cues, for example, temperature. To investigate this hypothesis, we tested the entrainability of the clock neurons to out-of-phase light and temperature cycles. When light-dark or light-dim light cycles were shifted by 12 h with respect to temperature cycles, behavioral rhythms of wild-type flies were re-entrained by the light cycles. In this condition, we found that TIMELESS (TIM) level was strongly influenced by the temperature cycles in many CRY-negative clock neurons, suggesting that the CRY-negative neurons have higher sensitivity to temperature. Under the same conditions, cry-null mutants entrained to the temperature cycles or very slowly re-entrained to light-dark cycles. Our results suggest that there are 2 types of clock neurons having differential sensitivities to light and temperature, and CRY is a key component for the preferential entrainment to light.
蓝光感光蛋白 Cryptochrome (CRY) 在果蝇生物钟的光同步中起着重要作用。此前，我们发现大约 150 个时钟神经元中，许多但不是所有神经元都表达 CRY。我们推测，CRY 阳性起搏神经元可能对光适应特别重要，而 CRY 阴性神经元可能对其他环境线索（例如温度）很重要。为了验证这一假说，我们测试了时钟神经元对非同步光和温度周期的适应能力。当光-暗或光-暗光周期相对于温度周期提前或延迟 12 小时时，野生型果蝇的行为节律通过光周期重新同步。在这种条件下，我们发现许多 CRY 阴性时钟神经元中 TIM 水平受温度周期的强烈影响，表明 CRY 阴性神经元对温度的敏感性更高。在相同条件下，cry 缺失突变体适应温度周期或非常缓慢地重新适应光-暗周期。我们的结果表明，存在两种对光和温度具有不同敏感性的时钟神经元，CRY 是优先适应光的关键组成部分。
