The effect of the doublesex gene in body colour masculinization of the damselfly Ischnura senegalensis |
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Authors: | Michihiko Takahashi Genta Okude Ryo Futahashi Yuma Takahashi Masakado Kawata |
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Affiliation: | 1.Graduate School of Life Sciences, Tohoku University, 6-3 Aramaki, Aoba, Sendai 980-8578, Japan;2.Department of Biological Sciences, Graduate School of Science, the University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan;3.Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, Tsukuba, Ibaraki 305-8566, Japan;4.Department of Biology, Graduate School of Science, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522, Japan |
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Abstract: | Odonata species display a remarkable diversity of colour patterns, including intrasexual polymorphisms. In the damselfly (Ischnura senegalensis), the expression of a sex-determining transcription factor, the doublesex (Isdsx) gene is reportedly associated with female colour polymorphism (CP) (gynomorph for female-specific colour and andromorph for male-mimicking colour). Here, the function of Isdsx in thoracic coloration was investigated by electroporation-mediated RNA interference (RNAi). RNAi of the Isdsx common region in males and andromorphic females reduced melanization and thus changed the colour pattern into that of gynomorphic females, while the gynomorphic colour pattern was not affected. By contrast, RNAi against the Isdsx long isoform produced no changes, suggesting that the Isdsx short isoform is important for body colour masculinization in both males and andromorphic females. When examining the expression levels of five genes with differences between sexes and female morphs, two melanin-suppressing genes, black and ebony, were expressed at higher levels in the Isdsx RNAi body area than a control area. Therefore, the Isdsx short isoform may induce thoracic colour differentiation by suppressing black and ebony, thereby generating female CP in I. senegalensis. These findings contribute to the understanding of the molecular and evolutionary mechanisms underlying female CP in Odonata. |
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Keywords: | doublesex RNA interference regulation of gene expression female-limited polymorphism damselfly |
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