Abstract:The full-length cDNA of ATG5 in Fenneropenaeus chinensis was cloned using rapid amplification of cDNA end (RACE) technology and named FcATG5. The tissue expression of FcATG5 and its expression characteristics under pH and carbonate alkalinity stress were analyzed using quantitative PCR. The function of ATG5 was verified using RNAi. Gene analysis showed that the FcATG5 gene cDNA consisted of 2225 bp with an open reading frame of 810 bp, encoding 269 amino acids, and has a predicted protein molecular weight of 31.103 kDa and a theoretical isoelectric point of 5.59. It is a hydrophobin, contains an autophagy-related protein domain (APG5), has no transmembrane structure, and does not contain signal peptides. The homology and phylogenetic analysis showed that FcATG5 was highly conserved and had the highest homology with Litopenaeus vannamei, reaching 98.14%. The tissue expression analysis showed that FcATG5 was expressed in all tissues of F. chinensis, with the highest expression in muscle, and the lowest expression in blood lymphocyte (P<0.05). The expression level of FcATG5 in the gill tissue was the highest at 96 h after pH stress, 2.67 times higher than that of the control group, and was the lowest at 48 h, which was 1.68 times higher than that of the control group. The expression level of FcATG5 in the gill tissue was the highest at 12 h after the carbonate alkalinity stress, 2.77 times higher than that of the control group, and was the lowest at 96 h, which was 1.30 times higher than that of the control group. The results of the interference experiments showed that under pH and carbonate alkalinity stress, silencing the FcATG5 gene significantly increased the mortality of F. chinensis (P<0.05), indicating that the higher the expression of this gene, the higher the survival rate of F. chinensis. The results of the study showed that the expression of FcATG5 was significantly increased under pH and carbonate stress (P<0.05). It is speculated that autophagy may be involved in the regulation of F. chinensis in response to abiotic stress. The results of this study are an important reference for the study of autophagy in aquatic animals, especially crustaceans, and will help advance the research of Chinese shrimp in saline-alkaline aquaculture systems.
