Genetic Variation of Insulin-like Growth Factor II (IGF-II) Gene and its Associations with Growth Traits in European sea bass (Dicentrarchus labrax)

Insulin-like growth factor II (IGF-II) is a peptide hormone which plays a crucial role in the growth and metabolic regulations of vertebrates. In this study, we identified single nucleotide polymorphisms on IGF-II gene in the European sea bass (Dicentrarchus labrax) and revealed the potential association between the genotypes of IGF-II gene and growth traits in 150 European sea bass. The polymorphisms were determined using DNA sequencing and PCR-RFLP methods in two different regions of IGF-II gene. An AT indel and two SNPs as g.5127711C>G and g.5127731G>T in the intron 2 region, and one SNP as g.5129188C>T in the intron 3 region of IGF-II gene in the European sea bass were reported for the first time with this study. Two different genotypes (GG, TG) were observed and the G allele was predominant (65%) in the IGF-II-Ndel locus. Associations between the genotypes of IGF-11-Ndel locus and body weight and total length were statistically significant (P<0.05). Body weight and total length in each group were higher for GG genotype of IGF-II-Ndel locus (p<0.05). In conclusion, the IGF-II-Ndel locus had a significant effect on the body weight and total length which could be useful for sea bass selection and breeding for marker-assisted selection program.