Skin mucosal immunity characteristics across populations and sexes in the endangered Brachymystax tsinlingensisLi 1966

This study compared the natural population (NP) and the second filial generation (SFGP) of Brachymystax tsinlingensis to evaluate differences in their immune and skin mucus characteristics. Enzyme-linked immunosorbent assay (ELISA) was employed to measure key markers of inflammation (IL-1β, IL-6), immunity (IgM, LZM), and antioxidant capacity (CAT, SOD), thereby investigating the immunological properties of skin mucus across populations and between sexes. The results showed that the NP had significantly higher levels of LZM and IL-6 in their skin mucus, whereas the SFGP exhibited higher levels of IL-1β, CAT, and SOD. Differences in IgM levels were also observed between the two populations. In both groups, females exhibited higher concentrations of these immune indicators in their skin mucus compared to males. These findings suggest that the NP and SFGP of Brachymystax tsinlingensis differ in their mucosal anti-inflammatory, immunological, and antioxidant capacities. Notably, SFGP displayed significantly greater antioxidant activity than the NP [CAT: P = 0.042 (P < 0.05); SOD: P = 0.001 (P < 0.001)]. Furthermore, females exhibited stronger mucosal immune, antioxidant, and anti-inflammatory responses than males. This study provides a comprehensive analysis of skin mucus immunity in Brachymystax tsinlingensis, offering insights to support conservation strategies and improve artificial reproduction efforts for this endangered species.