青海湖裸鲤FXYD基因家族鉴定、分子进化及表达

Genome-Wide Identification,Molecular Evolution,and Expression of FXYD Gene Family in Tibetan Naked Carp Gymnocypris przewalskii ssp.przewalskii

青海湖裸鲤是唯一一种适应青海湖高盐碱水环境的鲤科鱼类。苯丙氨酸-X-酪氨酸-天冬氨酸(FXYD)家族是一类小分子单跨膜蛋白,具有调节离子通道作用,在多种生物的盐度胁迫和盐度适应中发挥重要作用。笔者基于青海湖裸鲤全基因组数据,利用生物信息学方法,鉴定到16个青海湖裸鲤FXYD(gpFXYD)基因,通过多重序列比对和系统进化分析,16个gpFXYD基因成员分属于5个亚型。共线性分析表明,青海湖裸鲤FXYD基因家族中12个成员起源于全基因组复制,且与斑马鱼FXYD基因存在共线性,推测全基因组复制导致了青海湖裸鲤FXYD基因的加倍。分子进化分析显示,gpFXYD1b/1c和gpFXYD5c/5d基因的进化选择压力(Ka/Ks)>1,表明其在进化过程中受到了正选择,可能发生了适应性进化。不同亚家族在青海湖裸鲤多种组织表达中,gpFXYD1s基因在青海湖裸鲤的心脏和脑组织特异性表达,而gpFXYD7s基因在青海湖裸鲤的脑组织中特异表达,分析gpFXYD基因不同亚型可能在不同组织中发挥功能。组织表达中,gpFXYD5s、gpFXYD6s、gpFXYD11s基因在青海湖裸鲤肾脏和鳃组织中出现显著表达变化,表明gpFXYD5s、gpFXYD6s以及gpFXYD11s可能与青海湖裸鲤在高盐度条件下的离子运输和渗透压调节密切相关。试验结果可为解析青海湖裸鲤盐度适应奠定基础,同时也可为水产动物耐盐分子育种提供参考和借鉴。

Tibetan naked carp Gymnocypris przewalskii ssp . przewalskii is the only species of Schizothoracinae (Cyprinidae), which could adapt to the high saline-alkaline water environment in the Qinghai Lake. In the present study, we identified 16 FXYD genes in G. przewalskii ssp . przewalskii based on the G. przewalskii ssp . przewalskii genome. FXYD (Phen-XAA-Tyr-ASP) gene family encodes a group of small transmembrane proteins that regulate ion channel activities in responses to saline stress in a variety of organisms. Multiple sequence alignment and phylogenetic analysis suggested that 16 gpFXYD genes were divided into five subfamilies. Collinearity analysis indicated that 12 family members of the gpFXYD gene family were originated from genome-wide duplication, which showed synteny with their counterparts in zebrafish. This result suggested that the gain of extra copies of FXYD genes might be attributed to the whole genome duplication in G. przewalskii ssp . przewalskii. Molecular evolution analysis showed that the K a / K s values of gpFXYD1b/1c and gpFXYD5c/5d were greater than 1, which indicates that the positive selection might occur during evolution, leading to adaptive evolution. The subfamilies of gpFXYDs were expressed in diverse tissues, including heart, liver, brain, kidney, gill, intestine and gonado gpFXYD1s and gpFXYD7s were specifically expressed in the heart and brain. The results indicated that the function of gpFXYD subfamilys was in a tissue-dependent manner. After the transition from freshwater to saline water condition, the expression of gpFXYD5s, gpFXYD6s and gpFXYD11s showed significant changes in kidney and gill.The transcriptional variations might contribute to the ion transport and osmoregulation in G. przewalskii ssp . przewalskii at high salinity. The current study laid a foundation for understanding the adaptation of G. przewalskii ssp . przewalskii to high salinity environment, providing new insights into the molecular breeding of aquatic animals.