Single-cell transcriptomics unveils cellular adaptations to high-salinity stress in kidneys of GIFT tilapia

Fish osmoregulation was characterized by modifications in both the structure and functionality of numerous osmoregulatory cells and organs. Single-cell resolution investigations are imperative for comprehending the cellular processes involved in salinity-induced stress in fish. In this study, a cell atlas of the kidney of Genetically Improved Farmed Tilapia (GIFT) exposed to 27 ​ppt high-salinity stress for one month was established using scRNA-seq. We first identified 16 principal cell clusters, including podocytes (PODs), vascular endothelial cells (VasEndo), T cells, parietal epithelial cells (PECs), renal interstitial cells (RICs), vascular smooth muscle cells (SMCs), distal early tubule (DE), proximal convoluted tubule (PCT), B cells, hematopoietic stem/progenitor cells (HSPCs), macrophages/dendritic cells (MΦ/DCs), renal progenitor cells (RPCs), juxtaglomerular apparatus (JGA), proximal straight tubule (PST), and multiciliated cells (MCCs). A notable augmentation in the gene expression and proportions of PECs was observed, underscoring their pivotal function in the adaptive response of the kidney to high salinity stress. Analysis of RNA velocity unveiled a transitional connection between PECs and PODs, suggesting that PECs might act as precursor cells for PODs. Particularly, mature podocytes (MP) displayed resilience in high-salinity conditions, with kirrel1b , situated at the QTL region LG18: 26,733,536–26,809,639, pinpointed as a distinguishing novel gene marker for MP and a potential candidate gene for salinity endurance. Interestingly, the high-salinity levels substantially suppressed the expression of genes linked to lipid metabolism, such as plin2 , srebf2 , and dgat1 , in renal tubular epithelial cells (PCT, PST, and DE), indicating a decline in lipid droplet formation and lipid synthesis. These discoveries provided valuable perspectives into the cellular and molecular mechanisms involved in salinity adaptation in tilapia. • Sixteen principal cell clusters were delineated in GIFT tilapia kidney under 27 ppt salinity using single-cell RNA sequencing. • Parietal epithelial cells have an important function in the adaptive response of the kidney to high salinity stress. • Parietal epithelial cells might act as precursor cells for podocytes. • High salinity levels substantially suppressed the expression of genes linked to lipid metabolism.