Liu, Jie, Kang, Lijun, Decaluwe, Brandon, Gao, Jingwei, Xie, Zhixiong, Ma, Di, Ward, Alex, Yu, Yong, Inada, Hitoshi, Mori, Ikue, Xu, X.Z. Shawn, Nishio, Nana
[
International Worm Meeting,
2009]
It has long been assumed that the nematode C. elegans lacks the sense of light, mainly because it lives in the soil and does not have eyes. However, we have recently reported the surprising observation that C. elegans in fact possesses a simple visual system and engages in phototaxis behavior that is mediated by photoreceptor cells and light-sensitive channels [1]. Here we elucidate the phototransduction cascade in C. elegans photoreceptor cells through a combination of electrophysiological and behavioral analysis. As is the case with vertebrate photoreceptor cell rods and cones, C. elegans phototransduction is also mediated by G signaling and cGMP-sensitive CNG channels. Interestingly, instead of signaling through phosphodiesterases (PDEs), light-activated G proteins appear to be coupled to guanylate cyclases that produce cGMP, thereby resulting in opening of CNG channels. Our studies identify a new sensory modality in C. elegans and suggest that animals living in dark environments (e.g. soil and caves) may not be presumed to be blind. Our data also reveal a surprising conservation in phototransduction between vertebrates and C. elegans, indicating that C. elegans represents a powerful genetic model for the study of phototransduction. [1] Ward, A.*, Liu, J.*, Feng, Z., and Xu, X.Z.S. (2008) Light-sensitive neurons and channels mediate phototaxis in C. elegans. Nature Neuroscience 11, 916-22 *co-first authors.