哺乳动物视锥蛋白基因进化研究进展

视觉对于生物进化有重要意义,生物可以调整它们的视觉系统以应付它们所处的特定的光环境.认识和了解生物视觉系统感知的分子机制尤为重要,视蛋白基因氨基酸序列(基因型)和色素吸收光谱值λmax(表型)之间的关联使视蛋白基因成为研究视觉进化的一个很好的模式系统.研究表明,视蛋白基因以及视锥色素在哺乳动物进化中表现出显著的多样性,视觉感知的分子机制远比人们以前所认知的更为复杂和扑朔迷离.本文将评述近年来哺乳动物重要类群中视觉系统视蛋白基因进化研究进展,为进一步深入研究哺乳动物视觉感知的分子机制提供基础资料.

Parallel and Convergent Evolution of the Dim-Light Vision Gene RH1 in Bats (Order: Chiroptera)

Rhodopsin, encoded by the gene Rhodopsin (RH1), is extremely sensitive to light, and is responsible for dim-light vision. Bats are nocturnal mammals that inhabit poor light environments. Megabats (Old-World fruit bats) generally have well-developed eyes, while microbats (insectivorous bats) have developed echolocation and in general their eyes were degraded, however, dramatic differences in the eyes, and their reliance on vision, exist in this group. In this study, we examined the rod opsin gene (RH1), and compared its evolution to that of two cone opsin genes (SWS1 and M/LWS). While phylogenetic reconstruction with the cone opsin genes SWS1 and M/LWS generated a species tree in accord with expectations, the RH1 gene tree united Pteropodidae (Old-World fruit bats) and Yangochiroptera, with very high bootstrap values, suggesting the possibility of convergent evolution. The hypothesis of convergent evolution was further supported when nonsynonymous sites or amino acid sequences were used to construct phylogenies. Reconstructed RH1 sequences at internal nodes of the bat species phylogeny showed that: (1) Old-World fruit bats share an amino acid change (S270G) with the tomb bat; (2) Miniopterus share two amino acid changes (V104I, M183L) with Rhinolophoidea; (3) the amino acid replacement I123V occurred independently on four branches, and the replacements L99M, L266V and I286V occurred each on two branches. The multiple parallel amino acid replacements that occurred in the evolution of bat RH1 suggest the possibility of multiple convergences of their ecological specialization (i.e., various photic environments) during adaptation for the nocturnal lifestyle, and suggest that further attention is needed on the study of the ecology and behavior of bats.

脊椎动物视蛋白基因分子进化的研究进展

国家自然科学基金重点项目(30530120); 国家重点基础研究发展计划(2007CB411600)资助

UV wavelengths experienced during development affect larval newt visual sensitivity and predation efficiency

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