2026-03-27 九州大学
（A）本研究の成果：CpG部位の減少によりDNAメチル化を介した可塑性が失われ、既存の遺伝的変異から、より長い腸が固定される過程を示す。 （B）これまでわかっていたこと：エピジェネティックな修飾部位の喪失と新規形質の遺伝的固定を結びつける実証的データはなかった。
＜関連情報＞
- https://www.kyushu-u.ac.jp/ja/researches/view/1448
- https://www.kyushu-u.ac.jp/f/65294/26_0327_01.pdf
- https://www.pnas.org/doi/10.1073/pnas.2534817123
可塑性によって誘導される新規形質の遺伝的固定におけるDNAメチル化部位の喪失 DNA methylation site loss for plasticity-led novel trait genetic fixation
Takafumi Katsumura, Suguru Sato, Kana Yamashita, +13 , and Hiroki Oota
Proceedings of the National Academy of Sciences Published:March 25, 2026
DOI:https://doi.org/10.1073/pnas.2534817123
Significance
How environmentally induced traits become genetically fixed remains a fundamental puzzle in evolutionary biology. Using wild medaka fish populations, we found that seasonal DNA methylation changes control gut-length plasticity, and loss of these methylation sites enables genetic fixation of longer gut through standing genetic variation. This provides the molecular mechanism for “genetic assimilation”—the evolutionary process by which plastic traits become inherited. Our work bridges epigenetics and population genetics, revealing how organisms transition from flexible environmental responses to fixed adaptations. This mechanism may explain how species adapt to changing environments, with implications for understanding evolution under climate change.
Abstract
Phenotypic plasticity allows organisms to adapt traits in response to environmental changes, yet the molecular basis by which such plastic traits become genetically fixed remains unclear. Here, we investigated gut-length plasticity in medaka fish (Oryzias latipes) through genome-wide methylation profiling, CRISPR/Cas9-mediated deletion, and population genomic analyses. We found that seasonal methylation of CpG sites upstream of the Plxnb3 is correlated with gut-length plasticity, and deletion of this region abolishes plasticity. Additionally, standing variation in Ppp3r1 is associated with genetically fixed longer gut length in populations lacking plasticity. These results suggest that loss of epigenetic regulation via CpG site reduction triggers the genetic fixation of novel traits. Our findings provide molecular evidence linking epigenetic plasticity and genetic assimilation, advancing understanding of plasticity-led evolution in natural populations.
