鳥類における酸味耐性の分子進化を解明(Study Reveal Molecular Evolution of Sour Tolerance in Birds)

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2025-06-20 中国科学院(CAS)

鳥類における酸味耐性の分子進化を解明(Study Reveal Molecular Evolution of Sour Tolerance in Birds)The mechanism of environmental adaptation mediated by the evolution of the sour taste perception function in birds. (Image by ZHANG Hao)

中国科学院昆明動物研究所・賴任教授らの研究チームは、鳥類が酸性の高い果実を食べても嫌悪反応を示さず美味と感じる「酸味耐性」の分子進化メカニズムを解明しました。研究では、鳥類の酸味受容体OTOP1が低pH環境下で働きを抑制されることで、神経信号が弱まり酸味の不快感が減少することが確認されました。マウスにカナリア由来のOTOP1を導入すると酸味への神経反応が低下し、逆にハトやカナリアに薬理的にOTOP1を活性化すると果実の酸味を嫌う傾向が強まりました。さらに、カナリアにはG378という特定の変異があり、他の鳥よりも高い酸耐性を示すことも明らかに。進化的な観点からは、OTOP1の変異は甘味受容と共進化し、果食や生態的多様化、鳥類の放散進化を促進した可能性が示唆されます。この研究は、鳥類の感覚受容機能の進化が生態適応に果たす役割を理解する上で新たな知見を提供します。

<関連情報>

鳥類における酸耐性の分子進化 Molecular evolution of sour tolerance in birds

Hao Zhang, Lei Luo, Qiaoyi Liang, Lifeng Tian, […] , and Ren Lai
Science  Published:19 Jun 2025
DOI:https://doi.org/10.1126/science.adr7946

Editor’s summary

Many organisms find strongly sour flavors unappealing, likely due to their association with unripe or spoiled fruit. However, some bird species have developed a tolerance for highly acidic, sour flavors. Zhang et al. examined the genetic basis of sour taste perception in birds, finding that canary and pigeon alleles of the OTOP1 gene react to acid differently than mammalian alleles (see the Perspective by Rowland and Schneider). Indeed, gene knock-ins of the canary allele of OTOP1 into mice induced sour tolerance without otherwise affecting taste perception. A mutation shared by all songbirds seems to improve on the sour tolerance seen across other birds and may have contributed to the radiation of songbird species by diversifying dietary options. —Corinne Simonti

Abstract

Taste is crucial in shaping animal perception. Sourness, one of the primary tastes, is aversive in mammals, whereas many birds frequently consume acidic fruits, suggesting a potential tolerance. Our study uncovers a mechanism enabling avian sour tolerance that involves changes to the sour receptor [otopetrin 1 (OTOP1)]. We demonstrate that sour tolerance is a conserved trait in birds, with avian OTOP1 exhibiting acid-induced inhibition and OTOP1 modulation affecting sour perception and tolerance. Ancestral reconstruction reveals that the increase in acid tolerance may have evolved at the same point in the songbird phylogeny as the regain of sweet sensing in this clade. This shift might have enabled songbirds to feed on a wider range of fruits, affecting the evolution and diversification of the songbird radiation.

生物化学工学
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