Futahashi Ryo, Kawahara-Miki Ryouka, Kinoshita Michiyo, Yoshitake Kazutoshi, Yajima Shunsuke, Arikawa Kentaro, Fukatsu Takema
Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8566, Japan;
NODAI Genome Research Center, Tokyo University of Agriculture, Setagaya-ku, Tokyo 156-8502, Japan;
Proc Natl Acad Sci U S A. 2015 Mar 17;112(11):E1247-56. doi: 10.1073/pnas.1424670112. Epub 2015 Feb 23.
Dragonflies are colorful and large-eyed animals strongly dependent on color vision. Here we report an extraordinary large number of opsin genes in dragonflies and their characteristic spatiotemporal expression patterns. Exhaustive transcriptomic and genomic surveys of three dragonflies of the family Libellulidae consistently identified 20 opsin genes, consisting of 4 nonvisual opsin genes and 16 visual opsin genes of 1 UV, 5 short-wavelength (SW), and 10 long-wavelength (LW) type. Comprehensive transcriptomic survey of the other dragonflies representing an additional 10 families also identified as many as 15-33 opsin genes. Molecular phylogenetic analysis revealed dynamic multiplications and losses of the opsin genes in the course of evolution. In contrast to many SW and LW genes expressed in adults, only one SW gene and several LW genes were expressed in larvae, reflecting less visual dependence and LW-skewed light conditions for their lifestyle under water. In this context, notably, the sand-burrowing or pit-dwelling species tended to lack SW gene expression in larvae. In adult visual organs: (i) many SW genes and a few LW genes were expressed in the dorsal region of compound eyes, presumably for processing SW-skewed light from the sky; (ii) a few SW genes and many LW genes were expressed in the ventral region of compound eyes, probably for perceiving terrestrial objects; and (iii) expression of a specific LW gene was associated with ocelli. Our findings suggest that the stage- and region-specific expressions of the diverse opsin genes underlie the behavior, ecology, and adaptation of dragonflies.
蜻蜓是色彩斑斓且眼睛很大的动物，对颜色视觉高度依赖。在此，我们报告蜻蜓中数量异常多的视蛋白基因及其独特的时空表达模式。对蜻蛉科三种蜻蜓进行详尽的转录组和基因组调查，一致鉴定出20个视蛋白基因，其中包括4个非视觉视蛋白基因和16个视觉视蛋白基因，后者包括1个紫外型、5个短波长（SW）型和10个长波长（LW）型。对代表另外10个科的其他蜻蜓进行全面的转录组调查，也鉴定出多达15 - 33个视蛋白基因。分子系统发育分析揭示了视蛋白基因在进化过程中的动态倍增和丢失。与成虫中许多SW和LW基因表达不同，幼虫中仅表达1个SW基因和几个LW基因，这反映出幼虫生活方式对视觉依赖较少且水下光线条件偏向长波长。在此背景下，值得注意的是，穴居或坑居物种的幼虫往往缺乏SW基因表达。在成虫视觉器官中：（i）许多SW基因和少数LW基因在复眼背侧区域表达，可能用于处理来自天空的偏短波长光线；（ii）少数SW基因和许多LW基因在复眼腹侧区域表达，可能用于感知地面物体；（iii）一个特定的LW基因表达与单眼相关。我们的研究结果表明，多种视蛋白基因的阶段和区域特异性表达是蜻蜓行为、生态和适应性的基础。
