Circadian rhythms are driven by an endogenous clock which is synchronized by daily environmental cycles (known as zeitgebers). Although the circadian responses of C. elegans to light have been recently reported, the mechanisms and pathways involved in their synchronization are still unknown. Here we present, by means of a novel behavioral approach, a complete characterization of C. elegans circadian synchronization to light and temperature cycles. Moreover, we screened mutant strains in search of defects of photic and thermal responses in order to study their putative pathways.

We show that the wild-type strain is able to synchronize to combined cycles of light and temperature, with the best performance achieved under an optimal combination and phase-relationship of zeitgebers (high temperature in the dark phase and low temperature in the light phase). A lower responsiveness for the mutant strains MT21793 (lite-1/gur3 ko) and IK597 (gcy 8, 18 and 23 ko) was found in response to light and temperature, respectively. However, both mutants were still able to synchronize to a combined cycle of both stimuli. Our results shed light on the response of C. elegans to different zeitgebers as well as their possible synchronization pathways, the molecular components involved in these pathways, and their relative strength.

昼夜节律是由内源性时钟驱动的，该内源性时钟通过每日环境周期（称为Zeitgebers）同步。尽管最近已经报道了秀丽隐杆线虫对光的昼夜节律响应，但是其同步涉及的机制和途径仍然未知。在这里，我们通过一种新颖的行为方法，对秀丽隐杆线虫昼夜节律与光周期和温度周期的完整描述。此外，我们筛选突变菌株以寻找光和热响应的缺陷，以研究其推定的途径。

我们表明，野生型菌株能够与光和温度的组合循环同步，在Zeitgeber的最佳组合和相位关系下（暗相中的高温和光相中的低温）可以实现最佳性能。 。发现突变菌株MT21793（lite-1 / gur3ko）和IK597（gcy 8、18和23ko ）的响应性分别较低，分别响应于光和温度。但是，两个突变体仍然能够与两个刺激的联合循环同步。我们的结果揭示了秀丽隐杆线虫对不同zeitgebers的反应 以及它们可能的同步途径，这些途径中涉及的分子成分及其相对强度。