Nonadditive and allele-specific expression of ghrelin in hybrid tilapia.

BACKGROUND

Interspecies hybridization is an important breeding method to generate fishes with heterosis in aquaculture. Using this method, hybrid Nile tilapia (, ♀) × blue tilapia (, ♂) has been produced and widely farmed due to its growth and appetite superiorities. However, the genetic mechanism of these advanced traits is still not well understood. is a crucial gene that regulates growth and appetite in fishes. In the present study, we focused on the expression characteristics and its regulation of in the hybrid.

RESULTS

The tissue distribution analysis showed that was predominantly expressed in the stomach in the hybrid. was more highly expressed in the stomach in the hybrid and Nile tilapia, compared to blue tilapia, showing a nonadditive pattern. Two single-nucleotide polymorphism (SNP) sites were identified including T/C and C/G from the second exon in the gene from Nile tilapia and blue tilapia. By pyrosequencing based on the SNP sites, the allele-specific expression (ASE) of in the hybrid was assayed. The result indicated that in the hybrid showed higher maternal allelic transcript ratios. Fasting significantly increased overall expression at 4, 8, 12, 24, and 48 h. In addition, higher maternal allelic transcript ratios were not changed in the fasting hybrids at 48 h. The and effects were determined by evaluating the overall expression and ASE values in the hybrid. The expression of was mediated by compensating and effects in hybrid.

CONCLUSION

In summary, the present lines of evidence showed the nonadditive expression of in the hybrid tilapia and its regulation by subgenomes, offering new insight into gene expression characteristics in hybrids.