Investigation of molecular mechanism for sexual isolation using cichlid and medaka

染色体定位的负责二态着色(金色与正常)的基因座进行了研究。该候选区域包含约7个基因，多巴胺D2样受体基因可能是最有希望的候选负责基因。事实上，我们发现了Gold和正常等位基因之间的氨基酸替换，这将影响受体的功能。脊椎动物之间这种氨基酸的比较表明，正常等位基因来自Gold等位基因。我们建立了该基因的转基因青竹菌株；即错义突变、移码突变和构成表达Gold或正常等位基因的转基因菌株。在错义突变体方面，我们发现突变体的生存能力低于野生型兄弟姐妹，但体色与DRD2样蛋白之间的因果关系尚不清楚。本研究建立的其他菌株将有助于进一步研究该受体的功能。

Chromosomal mapping of the locus responsible for dimorphic coloration (Gold vs Normal) in Midas cichlid was performed. The candidate region contained about 7 genes, and the dopamine D2-like receptor gene could be the most promising candidate as the responsible gene. Indeed, we found an amino-acid substitution between the Gold and Normal alleles, which would affect function of the receptor. Comparison of this amino acid among vertebrates indicated that the Normal allele is derived from the Gold allele. We established genetically modified medaka strains of this gene; namely, missense mutants, frame-shift mutants, and transgenic strains that constitutively express the Gold or Normal allele. In terms of the missense mutants, we found that mutants were less viable than wild-type siblings, but causal relationship between body color and drd2-like remained unknown. Other strains established in this study will be helpful for further investigation of the function of this receptor.