Au David D, Liu Jenny C, Nguyen Thanh H, Foden Alexander J, Park Soo Jee, Dimalanta Mia, Yu Zhaoxia, Holmes Todd C
Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States.
Department of Statistics, Donald Bren School of Information and Computer Sciences, University of California, Irvine, Irvine, CA, United States.
Front Neurosci. 2022 Nov 30;16:1042508. doi: 10.3389/fnins.2022.1042508. eCollection 2022.
Nocturnal Anopheles mosquitoes exhibit strong behavioral avoidance to blue-light while diurnal Aedes mosquitoes are behaviorally attracted to blue-light and a wide range of other wavelengths of light. To determine the molecular mechanism of these effects, we expressed light-sensing Anopheles gambiae (AgCRY1) and Aedes aegypti (AeCRY1) Cryptochrome 1 (CRY) genes under a crypGAL4-24 driver line in a mutant Drosophila genetic background lacking native functional CRY, then tested behavioral and electrophysiological effects of mosquito CRY expression relative to positive and negative CRY control conditions. Neither mosquito CRY stops the circadian clock as shown by robust circadian behavioral rhythmicity in constant darkness in flies expressing either AgCRY1 or AeCRY1. AgCRY1 and AeCRY1 both mediate acute increases in large ventral lateral neuronal firing rate evoked by 450 nm blue-light, corresponding to CRY's peak absorbance in its base state, indicating that both mosquito CRYs are functional, however, AgCRY1 mediates significantly stronger sustained electrophysiological light-evoked depolarization in response to blue-light relative to AeCRY1. In contrast, neither AgCRY1 nor AeCRY1 expression mediates measurable increases in large ventral lateral neuronal firing rates in response to 405 nm violet-light, the peak of the Rhodopsin-7 photoreceptor that is co-expressed in the large lateral ventral neurons. These results are consistent with the known action spectra of type 1 CRYs and lack of response in cry-null controls. AgCRY1 and AeCRY1 expressing flies show behavioral attraction to low intensity blue-light, but AgCRY1 expressing flies show behavioral avoidance to higher intensity blue-light. These results show that nocturnal and diurnal mosquito Cryptochrome 1 proteins mediate differential physiological and behavioral responses to blue-light that are consistent with species-specific mosquito behavior.
夜间活动的按蚊对蓝光表现出强烈的行为回避，而日间活动的伊蚊则在行为上被蓝光以及其他多种波长的光所吸引。为了确定这些效应的分子机制，我们在缺乏天然功能性隐花色素（CRY）的突变果蝇遗传背景下，利用crypGAL4 - 24驱动系表达了具有光感应功能的冈比亚按蚊（AgCRY1）和埃及伊蚊（AeCRY1）的隐花色素1（CRY）基因，然后测试了相对于CRY阳性和阴性对照条件下，蚊子CRY表达的行为和电生理效应。在表达AgCRY1或AeCRY1的果蝇中，在持续黑暗条件下，强大的昼夜行为节律表明，两种蚊子的CRY都不会使生物钟停止运转。AgCRY1和AeCRY1都介导了由450 nm蓝光诱发的大腹外侧神经元放电率的急性增加，这与CRY在其基态下的峰值吸光度相对应，表明两种蚊子的CRY都是有功能的。然而，相对于AeCRY1，AgCRY1介导的对蓝光的持续电生理光诱发去极化显著更强。相比之下，AgCRY1和AeCRY1的表达都不会介导对405 nm紫光的大腹外侧神经元放电率的可测量增加，405 nm紫光正是在大腹外侧神经元中共表达的视紫红质-7光感受器的峰值。这些结果与已知的1型CRY的作用光谱以及cry基因敲除对照中的无反应情况一致。表达AgCRY1和AeCRY1的果蝇对低强度蓝光表现出行为吸引，但表达AgCRY1的果蝇对高强度蓝光表现出行为回避。这些结果表明，夜间和日间活动的蚊子隐花色素1蛋白介导了对蓝光的不同生理和行为反应，这与特定物种的蚊子行为一致。
