The Dongtingking crucian carp, Carassius auratus indigentiaus , a unique and economically vital subspecies endemic to the Dongting Lake system with superior growth rate and nutritional value, faces significant disease threats under intensive aquaculture; however, the molecular basis of its first line of immune defense – the skin mucus proteome – remains completely unexplored. This study investigated the protein composition and function of the skin mucus in Dongtingking crucian carp, with a specific focus on identifying immune-related proteins. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was employed to identify proteins in the mucus, and functional enrichment analyses were performed based on Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG). The results showed that a total of 1,903 proteins were identified in the mucus of Dongtingking crucian carp. GO enrichment analysis indicated that these proteins were primarily involved in biological processes such as metabolic processes, cellular component organization or biogenesis, macromolecule localization, cellular localization, and response to stress. Molecular function analysis indicated that among major enzyme categories, proteins with hydrolase activity constituted the largest group, comprising 308 protein sequences. KEGG pathway analysis showed significant enrichment in ribosome, bacterial infection, phagosome, and cell adhesion pathways. The study identified various immune-related proteins, including lectins, lysozyme, transferrin-a (tfa), hemopexin, complement components, heat shock proteins, superoxide dismutase, mucin-2-like and alpha-2-macroglobulin-like proteins. This research provides the first comprehensive dataset on the protein composition of skin mucus of Dongtingking crucian carp, which holds significant importance for future research on gene function, elucidation of mucus immune mechanisms, prevention and control of fish diseases, and resource conservation.
Zhou et al. (Fri,) studied this question.