Zhou Bingzheng, Sui Ruichen, Yu Luxian, Qi Delin, Fu Shengyun, Luo Ying, Qi Hongfang, Li Xiaohuan, Zhao Kai, Liu Sijia, Tian Fei
Key Laboratory of Adaptation and Evolution of Plateau Biota, Qinghai Key Laboratory of Animal Ecological Genomics, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, No. 23 Xinning Road, Xining, 810008, China.
State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining, 810006, China.
BMC Genomics. 2025 Feb 19;26(1):162. doi: 10.1186/s12864-025-11336-z.
Gymnocypris przewalskii is an exclusively cyprinid fish that inhabits Lake Qinghai, which is characterized by high salinity and alkalinity. To elucidate the molecular basis of the adaptation of G. przewalskii to a wide range of salinity‒alkalinity conditions, we performed morphological, biochemical, transcriptomic and proteomic analyses of the major osmoregulatory organs of the gills and kidney. Morphological examination revealed that mitochondria-rich cells were replaced by mucus cells in the gills during the transition of G. przewalskii from freshwater to lake water. In the kidney, the tight junction formed dense structure in the renal tubules under lake water condition compared with the loose structure in freshwater. The results of the biochemical assays revealed an increased content of total amino acids, indicating their potential roles as osmolytes and energy supplies in freshwater. The decreased urea concentration suggested that urea synthesis might not be involved in the detoxicity of ammonia. The transcriptomic and proteomic data revealed that genes involved in ion absorption and ammonia excretion were activated in freshwater and that genes involved in cell junction and glutamine synthesis were induced in lake water, which was consistent with the morphological and biochemical observations. Together with the higher levels of glutamine and glutamate, we proposed that G. przewalskii alleviated the toxic effect of ammonia direct excretion through gills under freshwater and the activation of the conversion of glutamate to glutamine under high saline-alkaline condition. Our results revealed different expression profiles of genes involved in metabolic pathways, including the upregulation of genes involved in energy production in freshwater and the induction of genes involved in the synthesis of acetylneuramic acid and sphingolipid in soda lake water. In conclusion, the appearance of mitochondria-rich cells and increased energy production might contribute to ion absorption in G. przewalskii to maintain ion and solute homeostasis in freshwater. The existence of mucus cells and dense junctions, which are associated with increased gene expression, might be related to the adaptation of G. przewalskii to high salinity-alkalinity.
普氏裸鲤是一种仅分布于青海湖的鲤科鱼类，青海湖具有高盐碱性的特征。为阐明普氏裸鲤适应广泛盐碱性条件的分子基础，我们对鳃和肾脏等主要渗透调节器官进行了形态学、生化、转录组和蛋白质组分析。形态学检查显示，在普氏裸鲤从淡水过渡到湖水的过程中，鳃中富含线粒体的细胞被黏液细胞取代。在肾脏中，与淡水中疏松的结构相比，在湖水条件下肾小管中的紧密连接形成了致密结构。生化分析结果显示总氨基酸含量增加，表明它们在淡水中作为渗透溶质和能量供应的潜在作用。尿素浓度降低表明尿素合成可能不参与氨的解毒。转录组和蛋白质组数据显示，参与离子吸收和氨排泄的基因在淡水中被激活，而参与细胞连接和谷氨酰胺合成的基因在湖水中被诱导，这与形态学和生化观察结果一致。结合较高水平的谷氨酰胺和谷氨酸，我们提出普氏裸鲤在淡水中通过鳃直接排泄氨时减轻了氨的毒性作用，并在高盐碱条件下激活了谷氨酸向谷氨酰胺的转化。我们的结果揭示了参与代谢途径的基因的不同表达谱，包括淡水中参与能量产生的基因上调以及苏打湖水中参与乙酰神经氨酸和鞘脂合成的基因诱导。总之，富含线粒体的细胞的出现和能量产生的增加可能有助于普氏裸鲤在淡水中进行离子吸收以维持离子和溶质稳态。黏液细胞和致密连接的存在与基因表达增加有关，可能与普氏裸鲤对高盐碱性的适应有关。
