研究成果の概要(和文):多くの昆虫複眼は２タイプの個眼を含むが、チョウではこれが３タイプである。これは訪花性への適応なのか？この疑問に答えるため、複眼の形成過程をチョウとハエで比較した。ハエでは、全個眼で調節因子Prospero(Pros)がR7細胞に発現する。Prosはチョウでは個眼当り２細胞に発現していた。チョウではR7が重複したらしい。ハエの個眼多様性は、R7にSpineless(Ss)が発現するか否かで決まる。チョウ個眼ではSs陽性細胞数が２か１か０で、３タイプの個眼に対応すると考えられた。実際ssの機能を止めると、全個眼に紫外受容細胞が２個できた。複眼の分光学的多様性は視細胞数の増加と関係あるようだ。
研究成果の概要(英文):Compound eyes of many insects consists of two spectrally-heterogeneous ommatidia. The number is butterflies and bees, making their eyes spectrally richer. Is this an adaptation for having better color vision in flower-visitors? We addressed this question by comparing the eye development in flies and butterflies. A transcription factor Prospero (Pros) is expressed in a short-wavelength receptor, R7, in all commatidia in flies. We found Pros is expressed in two cells per an ommatidium in butterflies : R7 seems to be duplicated. Ommatidial heterogeneity is detected in flies by stochastic expression of Spineless (Ss) in R7. In butterflies, two R7-like cells express Ss in three patterns, on/off, on/on and off/off, as if they correspond to three ommatidial types. In fact, butterflies whose ss gene is knockes-out have the UV-UV type commatidia. It thus appears that the spectral richness of butterfly eyes is associated with duplication of R7-like cell in the process of adaptation.
複眼進化研究の新機軸：視細胞のdeep homology
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