Comparative proteomic analyses of resistant and susceptible crucian carp to Gyrodactylus kobayashii infection

Abstract

Gyrodactylid monogeneans are common parasites of teleost fishes characterized by high host specificity. Host specificity and its underlying mechanisms of monogenean have been always a fascinating issue that has attracted considerable attention from researchers. However, the molecular mechanism responsible for the host specificity of monogenean is still not yet fully understood. In this study, the susceptibility to Gyrodactylus kobayashii of different species or varieties in the genus Carassius was investigated. Furthermore, the proteome changes in the skin mucus of resistant and susceptible fish were analyzed by Tandem Mass Tags (TMT) quantitative proteomics method. The experimental results indicated that G. kobayashii was found in 12 varieties of goldfish and ChangFeng C. auratus gibelio with different degrees of infection percentage, while no G. kobayashii was found in C. auratus gibelio var. CAS Ⅴ. Population dynamics of G. kobayashii on red white common goldfish and C. auratus gibelio var. CAS Ⅴ showed distinct trends in the in vivo infection experiment. These results demonstrated C. auratus gibelio var. CAS Ⅴ is a resistant fish to G. kobayashii. Proteomic analysis revealed that 41 differentially expressed proteins (DEPs), including 25 up-regulated and 16 down-regulated proteins, were identified. Bioinformatics analysis indicated these DEPs were involved in multiple biological functions including immunity, metabolism, and signal transduction. Among them, some immune-related proteins, such as cadherin-1, serotransferrin, and glutathione transferase in the fish mucus might be potential determinants of the host susceptibility to G. kobayashii. Also, some structural and energy metabolism-related DEPs, such as small muscular protein, keratin and vitelline membrane outer layer protein served as a source of nutrition and might also affect host susceptibility. Overall, this study not only provided systematic protein information of crucian carp skin mucus but also identified some potential candidate proteins that might be related to host susceptibility to G. kobayashii.