東アフリカ遊牧民の水ストレス適応に関わる遺伝的変化を発見(Genetic adaptations helped East African nomadic pastoralists adapt to constant water stress)

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2025-11-06 カリフォルニア大学サンタバーバラ校(UCSB)

カリフォルニア大学サンタバーバラ校を含む国際研究チームは、ケニア北西部の遊牧民族トゥルカナ族が、乾燥・高温環境と高タンパク食に適応する遺伝的進化を遂げてきたことを明らかにした。367人のゲノム解析から、腎臓で尿濃縮を促進し水分を保持する遺伝子領域が自然選択を受けていることが判明。これにより慢性的脱水や高タンパク血症にも耐える体質を持つ。一方、都市化により水と炭水化物が豊富な生活へ移行した人々では、高血圧や糖尿病リスクが上昇する「進化的不一致」が懸念される。研究成果はScience誌に掲載。

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ケニア北西部のトゥルカナにおける水ストレスと牧畜への適応 Adaptations to water stress and pastoralism in the Turkana of northwest Kenya

A. J. Lea, I. V. Caldas, K. M. Garske,E. R. Gerlinger, […] , and J. F. Ayroles
Science  Published:18 Sep 2025
DOI:https://doi.org/10.1126/science.adv2467

Editor’s summary

Humans have adapted to many environments, dietary shifts, and conditions. Lea et al. analyzed blood markers and genomes from 367 Turkana individuals in northwest Kenya (see the Perspective by McVay and Goldberg). This group has primarily practiced nomadic pastoralism in an extremely arid environment for the past 5000 to 8000 years, with as much as 80% of their traditional diet being composed of animal products. The authors identified several regions of the genome that appear to be under recent selection, including one near the gene STC1, which is involved in the kidneys’ response to dehydration. The authors also shared the results with these groups, which may help them be more aware of possible medical complications as some individuals move to urban centers. —Corinne Simonti

Abstract

The Turkana pastoralists of Kenya inhabit arid, water-limited environments and rely largely on livestock for subsistence. Working with Turkana communities, we sequenced 367 whole genomes and identified eight regions with evidence for recent positive selection. One of these regions includes a putative regulatory element for STC1—a kidney-expressed gene involved in metabolism and the response to dehydration. We show that STC1 is induced by antidiuretic hormone in human cells, is associated with urea levels in the Turkana themselves, and is under strong and recent selection in this population as well as a second East African population, the Daasanach. This work highlights how integrating anthropological and genomic approaches can lead to a new understanding of human physiology with biomedical relevance.

細胞遺伝子工学
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