NaHCO3碱度驯化下黑鲷应激响应与耐受机制OA北大核心

To explore the responses and adaptive mechanisms underlying long-term acclimation of Acanthopagrus schlegelii(blackhead seabream)to NaHCO3-induced alkalinity,this study used juveniles as the research subjects and conducted a 50-day alkalinity acclimation experiment.It compared the differences in gill histology,gill tran-scriptomics,and serum physiological parameters among the 16 and 32 mmol/L NaHCO3 treatment and control groups.Histological analysis revealed that prolonged exposure to alkalinity induced hyperplasia of the gill lamellae and edema in the epithelial cells and interstitium.At the molecular level,alkaline stress upregulated tight junc-tion-related genes,strengthening intercellular connections and reducing permeability to resist the adverse effects.Gill remodeling was closely related to cell apoptosis and proliferation.In the 16 mmol/L group,apoptosis occurred initially,and the cells then recovered.However,in the 32 mmol/L group,apoptosis was insignificant due to low APAF1 levels.The group was also in a hypoxic state,with the upregulation of hypoxia-inducible factors and inhibi-tion of proliferation-related pathways.In terms of ion transport and ammonia regulation,the downregulation of AQP3a contributed to gill edema;NBCe1,CA-Ⅱ,and ammonia transporter-encoding genes such as Rhcga,Rhcgb,and Rhbg were initially upregulated in response to alkaline stress.After long-term acclimation,Rhcgb levels re-mained high in the 16 mmol/L group,resulting in lower serum NH3 content and pH,lactate,but other indicators remained stable across all treatment groups.In summary,at 16 mmol/L,ammonia excretion was enhanced through the remodeling of gill morphology and the synergistic action of ion-regulatory genes and ammonia transporters.At 32 mmol/L,blackhead seabream maintained cellular function at a high energy cost through hypoxia-induced path-ways,inhibiting cell apoptosis and proliferation and perpetuating ammonia homeostasis through regulating ion lev-els and ammonia transporters.This study helps to further understand the adaptive regulatory mechanisms of black-head seabream under alkaline conditions and provides a theoretical basis for the selection and cultivation of salt-and alkali-tolerant fish species.