TRANSCRIPTOME ANALYSIS OF PROTEIN METABOLISM IN RESPONSE TO DIETARY LINOLENIC ACIDIN NILE TILAPIA, Oreochromis Niloticus

Qing Pan*, Xiong Yuanyan, Gan Lian, Wang Yadi, Cheng Cuiying, Li Xiaoxia, Cheng Biao
Department of Aquaculture, College of Animal Science, South China Agriculture University, Guangzhou 510642, China (qpan@scau.edu.cn)

In the present study, RNA-seq was used to identify the differential gene expression profile, gene ontology and pathways related to Nile tilapiai in response to dietary α-linolenic acid (LNA). Juvenile fish with initial average body weight of 1.7g were fed test diets in triplicate tanks for 10 weeks. Three test diets with the same protein level of 25% were added with LNA at 0%, 0.5% and 1.5%, respectively. At the end of feeding, dorsal muscle of fish were sampled for RNA-seq analysis. The result showed that above 335 million clean reads were filtered from 368,338,206 raw reads in which more than 85% of clean reads could be mapped to the Nile tilapia reference genome. Compare to fish fed diet without LNA, 391 differentially expressed genes (DEGs) were found in group with 0.5% LNA (including 358 up-regulated and 33 down-regulated) and 375 differentially expressed genes were found in group with 1.5% LNA (including 292 up-regulated and 83 down-regulated). According to gene ontology (GO) terms for biological process and pathways in those DEGs, 28 significant common GO terms were obtained in groups of 0.5% and 1.5% LNA compared to the group without LNA. GO annotation were significantly related to amino acid and protein metabolism, including tryptophan catabolic process, proteolysis, cysteine-type endopeptidase inhibitor activity, L-amino acid activity, L-amino acid transport, L-amino acid transmemberane transport. The DEGs were analyzed by KEGG Pathway Analysis and uncover pathways in LNA model. 10 significant common KEGG pathways were obtained based on DEGs interestingly in which 4 pathways were related to amino acid metabolism including cysteine and methionine metabolism, beta-LNAnine metabolism, tryptophan metabolism and lysine biosynthesis. These results suggested that α-linolenic acid could affact protein metabolism by transportition, catabolic, biosynthesis process of some amino acids and proteolysis process.