Abstract：
Understanding how evolutionary processes shape the genetic variations and influence the response of species to environmental alterations is critical for biodiversity conservation and molecular breeding. Gymnocypris przewalskii przewalskii is the only known cyprinid fish that dwells in the brackish water of Lake Qinghai on the Qinghai-Tibetan Plateau. To reveal the genetic basis of its adaptation to high salinity and alkalinity, whole-genome sequencing was performed in G. p. przewalskii and its freshwater relatives Gymnocypris eckloni and Gymnocypris przewalskii ganzihonensis. Compared with freshwater species, lower genetic diversity and higher linkage disequilibrium were observed in G. p. przewalskii. Selective sweep analysis identified 424 core-selective genes enriched in transport activities. Transfection analysis showed that genetic changes in the positively selected gene aquaporin 3 (AQP3) improved cell viability after salt treatment, suggesting its involvement in brackish water adaptation. Our analysis indicates that ion and water transporter genes experienced intensive selection, which might have contributed to the maintenance of high osmolality and ion content in G. p. przewalskii. The current study identified key molecules involved in the adaptation of fish to brackish water, providing valuable genomic resources for the molecular breeding of salt-tolerant fish.
摘要：
了解进化过程如何塑造遗传变异并影响物种对环境变化的反应对于生物多样性保护和分子育种至关重要。Gymnocyprisprzewalskiiprzewalskii是唯一一种居住在青藏高原青海湖微咸水中的鲤鱼。揭示其适应高盐度和碱度的遗传基础,在G.p.przewalskii及其淡水亲戚Gynocypriseckloni和Gymnocyprisprzewalskiiganzihonensis中进行了全基因组测序。与淡水物种相比，在G.p.przewalskii中观察到较低的遗传多样性和较高的连锁不平衡。选择性扫描分析鉴定了424个富含转运活性的核心选择性基因。转染分析表明，盐处理后，阳性选择基因水通道蛋白3（AQP3）的遗传变化提高了细胞活力，表明它参与了微咸水的适应。我们的分析表明离子和水转运蛋白基因经历了密集的选择，这可能有助于保持G.p.przewalskii的高渗透压和离子含量。目前的研究确定了参与鱼适应微咸水的关键分子，为耐盐鱼类的分子育种提供了宝贵的基因组资源。
