Comparative analysis of quantitative phosphoproteomics between two tilapias (Oreochromis niloticus and Oreochromis aureus) under low-temperature stress

Abstract

As an important farmed fish, tilapia has poor tolerance to low-temperatures. At the same time, different tilapia strains have apparent differences in low-temperature tolerance. In this study, using the iTRAQ method, the phosphorylated proteomics of two tilapia strains (Oreochromis niloticus and Oreochromis aureus) with different tolerances to low-temperature stress were quantitatively and comparatively analyzed, to clarify the physiological mechanism of tilapia's response to low-temperature stress. Through the GO and IPR analyses of differentially phosphorylated proteins, a number of similarities in physiological activities and regulatory effects were found between the two tilapias in response to low-temperature stress. Many differentially phosphorylated proteins are mainly involved in lipid metabolism, cell proliferation and apoptosis. However, the difference in endurance of low temperature of these two tilapias might be related to the differences in categories, expression and modification level of genetic products which were involved in the aforementioned physiological processes. And meanwhile, the enrichment results of KEGG showed the changes of multiple immune-related and growth-related phosphorylated proteins in the cytokine-cytokine receptor interaction pathway in O. aureus are more prominent. Furthermore, the significantly enriched pathway of carbohydrate digestion and absorption in O. niloticus may indicate that low-temperature stress exerts a more severe impact on energy metabolism. The relative results would help elucidating the molecular mechanism by which tilapia responds to low-temperature stress, and developing culture of tilapia species.

Keywords: Hypothermy; Omics; Phosphorylation; Tilapia.

Figure 1. The length distribution of the total identified peptides from two tilapias.

The horizontal axis shows the length of the peptides (i.e., the number of amino acids), and the vertical axis shows the number of peptides.

Figure 2. The protein coverage distribution of the total identified proteins in the two tilapias.

Figure 3. Statistical analysis of protein modification sites.

(A) The distribution of the number of phosphorylation sites on phosphorylated proteins; (B) The proportional distribution of phosphorylation sites on Ser (S), Thr (T) and Tyr (Y).

Figure 4. GO enrichment analysis of phosphorylated proteins with significantly differential phosphorylation sites from O. niloticus and O. aureus.

(A) GO enrichment analysis of phosphorylated proteins from O. niloticus; (B) GO enrichment analysis of phosphorylated proteins from O. aureus.

Figure 5. KEGG enrichment analysis of phosphorylated proteins with significantly differential phosphorylation sites from O. niloticus and O. aureus.

(A) KEGG enrichment analysis of phosphorylated proteins from O. niloticus; (B) KEGG enrichment analysis of phosphorylated proteins from O. aureus.

Figure 6. IPR enrichment analysis of phosphorylated proteins with significantly differential phosphorylation sites from O. niloticus and O. aureus.

(A) IPR enrichment analysis of phosphorylated proteins from O. niloticus; (B) IPR enrichment analysis of phosphorylated proteins from O. aureus. IPRs with a P value ≤0.05 are marked with an asterisk (*).

Figure 7. Interaction analysis of differentially phosphorylated proteins.

(A) Interaction analysis of the apoptotic chromatin condensation inducer in the nucleus based on the reference library of O. niloticus; (B) Interaction analysis of CAD protein based on the reference database of zebrafish.

Figure 8. Interaction analysis of differentially phosphorylated proteins.

(A) Interaction analysis of IQ motif and SEC7 domain-containing proteins based on the reference library of O. niloticus; (B) Interaction analysis of tyrosine-protein kinase ABL1 based on the reference database of zebrafish.