Department of Biology, Graduate School of Science, Osaka Metropolitan University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan.
Department of Biology and Geosciences, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan.
Philos Trans R Soc Lond B Biol Sci. 2022 Oct 24;377(1862):20210274. doi: 10.1098/rstb.2021.0274. Epub 2022 Sep 5.
Insect vision starts with light absorption by visual pigments based on opsins that drive Gq-type G protein-mediated phototransduction. Since , the most studied insect in vision research, has only Gq-coupled opsins, the Gq-mediated phototransduction has been solely focused on insect vision for decades. However, genome projects on mosquitos uncovered non-canonical insect opsin genes, members of the Opn3 or c-opsin group composed of vertebrate and invertebrate non-visual opsins. Here, we report that a homologue of Opn3, MosOpn3 (Asop12) is expressed in eyes of a mosquito . hybridization analysis revealed that MosOpn3 is expressed in dorsal and ventral ommatidia, in which only R7 photoreceptor cells express MosOpn3. We also found that Asop9, a Gq-coupled visual opsin, exhibited co-localization with MosOpn3. Spectroscopic analysis revealed that Asop9 forms a blue-sensitive opsin-based pigment. Thus, the Gi/Go-coupled opsin MosOpn3, which forms a green-sensitive pigment, is co-localized with Asop9, a Gq-coupled opsin that forms a blue-sensitive visual pigment. Since these two opsin-based pigments trigger different phototransduction cascades, the R7 photoreceptors could generate complex photoresponses to blue to green light. This article is part of the theme issue 'Understanding colour vision: molecular, physiological, neuronal and behavioural studies in arthropods'.
昆虫视觉始于视色素对光的吸收，视色素基于视蛋白，视蛋白驱动 Gq 型 G 蛋白介导的光传导。由于 在视觉研究中是研究最多的昆虫，它只具有与 Gq 偶联的视蛋白，因此 Gq 介导的光转导在过去几十年中一直专注于昆虫视觉。然而，蚊子的基因组项目揭示了非典型的昆虫视蛋白基因，它们是 Opn3 或 c-视蛋白组的成员，由脊椎动物和无脊椎动物的非视觉视蛋白组成。在这里，我们报告了 Opn3 的同源物 MosOpn3（Asop12）在蚊子 的眼睛中表达。 杂交分析表明，MosOpn3 在背和腹小眼中表达，其中只有 R7 光感受器细胞表达 MosOpn3。我们还发现，Gq 偶联的视觉视蛋白 Asop9 与 MosOpn3 共定位。光谱分析表明，Asop9 形成一种对蓝光敏感的视蛋白基色素。因此，与 Gq 偶联的视蛋白 Asop9 形成一种对蓝光敏感的视觉色素，Gi/Go 偶联的视蛋白 MosOpn3 形成一种对绿光敏感的色素。由于这两种视蛋白基色素触发不同的光转导级联反应，R7 光感受器可以对蓝光到绿光产生复杂的光反应。本文是主题为“理解颜色视觉：节肢动物的分子、生理、神经元和行为研究”的一部分。
