Genome-wide identification and expression analysis of the aquaporin gene family reveals the role in the salinity adaptability in Nile tilapia (Oreochromis niloticus).

BACKGROUND

Nile tilapia (Oreochromis niloticus), an important economic freshwater fish being cultured globally, is highly adaptable to a wide range of salinities. However, little information is currently available on the mechanism of salinity adaptation.

OBJECTIVE

For a better understanding of this intriguing adaptability, we identified and analyzed aquaporins (AQPs), which are channel proteins with a basic function of intracellular and intercellular transportation for water and certain solutes.

METHODS

In the present study, we performed genome-wide identification and comprehensive analysis of the duplicated AQP genes in Nile tilapia by bioinformatics methods. Tissue-specific analyses were then combined with transcriptome data under different salinity treatments.

RESULTS

It was revealed that Nile tilapia has a total of twenty-eight AQPs, which are distributed unevenly on twelve chromosomes and belong to four subfamilies according to phylogenetic analysis. These AQPs share conserved AQP characteristic structural domains and motifs, although they differ in molecular weight from 23 to 36 kDa and contain distinct sequences. GO analysis revealed that most AQPs have transporter protein activity and are involved in biological processes such as substance transport, stress response, development and metabolism. KEGG enrichment analysis showed that AQPs were significantly enriched in two pathways, anti-diuretic hormone-regulated reabsorption and bile secretion.

CONCLUSION

These results suggested that Nile tilapia has a highly developed, albeit complex, osmotic pressure regulation system, which provided a molecular basis for exploring how these AQP members coordinate to help Nile tilapia cope with different salinities.