Neuronal and genetic basis of photosensory behavior in C. elegans

描述（由申请人提供）：我们研究的长期目标是了解动物如何感知和反应环境线索。目前的建议侧重于光的感觉，这是一种对动物生命至关重要的感官形态。光是由视网膜上的感光细胞检测到的，在那里它们调节图像形成的视觉。此外，感光细胞，特别是眼外感光细胞，介导非成像功能，如趋光性、昼夜节律、瞳孔收缩和磁定向。虽然图像形成视觉已被广泛表征，但相对而言，人们对光感受器细胞非图像形成功能的机制知之甚少。秀丽隐杆线虫是研究化学感觉（如嗅觉和味觉）和机械感觉（如触觉和本体感觉）等感觉转导的一种流行的遗传模式生物。但是秀丽隐杆线虫生活在黑暗（土壤）中，而且没有眼睛，因此被认为没有光感。有趣的是，我们最近证明了这些没有眼睛的动物，令人惊讶的是，拥有光感，并参与光感行为（趋光性），使它们能够避免致命剂量的光，也提供了一个潜在的

DESCRIPTION (provided by applicant): The long term goal of our research is to understand how animals sense and react to environmental cues. The current proposal focuses on the sense of light, a sensory modality critical for animal life. Light is detected by photoreceptor cells in he retina where they mediate image-forming vision. In addition, photoreceptor cells, particularly those extra-ocular photoreceptor cells, mediate non-image-forming functions such as phototaxis, circadian rhythms, pupil constriction, and magnetic orientation. While the image-forming vision has been extensively characterized, relatively little is known about the mechanisms of the non-image-forming functions of photoreceptor cells. The nematode C. elegans is a popular genetic model organism for the study of sensory transduction such as chemosensation (e.g. olfaction and taste) and mechanosensation (e.g. touch sensation and proprioception). However, C. elegans were believed to lack the sense of light, as they live in darkness (soil) and also do not have eyes. Interestingly, we have recently demonstrated that these eyeless animals, surprisingly, possess the sense of light and engage in photosensory behavior (phototaxis) that allows them to avoid lethal doses of light and also provides a potential mechanism for retaining them in dark environments. Intriguingly, a similar phenomenon also exists in other organisms, such as Drosophila larva, which requires extra-ocular photoreceptor cells. Here we propose to elucidate the mechanisms underlying photosensation in C. elegans. We will identify all the photoreceptor cells required for phototaxis, determine the signaling mechanisms in photoreceptor cells, and identify the photoreceptor protein. We will take a multidisciplinary approach combining genetics, behavioral analysis, pharmacology, biochemistry, and electrophysiology. The proposed study will provide novel insights into the mechanisms of the non-image-forming functions of photoreceptor cells in mammals. PUBLIC HEALTH RELEVANCE: Abnormalities in photosensation lead to a variety of human diseases, including eye diseases and sleep disorders. The proposed studies will facilitate our understanding of photosensation and related diseases.