Characterisation of Single Nucleotide Polymorphisms and Haplotypes of MSTN Associated with Growth Traits in European Sea Bass (Dicentrarchus labrax).

The myostatin (MSTN) gene, known as growth differentiation factor-8 (GDF-8), is a member of the transforming growth factor-ß (TGF-ß) superfamily and plays a specific inhibitory role during the critical phases of skeletal muscle mass development in vertebrates. This study was conducted to investigate MSTN polymorphisms in harvest size European sea bass reared in Turkey. Nine single nucleotide polymorphisms (SNPs) and two indels were identified in exons 1-3 of MSTN in the European sea bass population The associations between the g.16612A indel located in intron 1 and standard length were significant. The MSTN g.15252 T > A locus in intron 2 was significantly related to the total weight, fillet weight and standard length (P < 0.05). The relationship between the g.14873C > T locus in exon 3 of MSTN and standard height, head length, body length, pre-anal length, abdominal length, post-anal length and head width was significant (P < 0.05). According to the results of the haplotype analysis, two haplogroup and eight haplotype combinations were detected in the population. The haplogroup 2 had significant associations with all measured growth traits (P < 0.05). Thus, SNPs and haplotypes identified in this study could be useful for European sea bass breeding and marker-assisted selection.

Associations between genetic variants of the insulin-like growth factor I (IGF-I) gene and growth traits in European sea bass (Dicentrarchus labrax, L.).

The IGF-I is a significant peptide hormone to cell growth, development, reproduction, and metabolism of teleost fish. This study was conducted to investigate the IGF-I gene polymorphism and to reveal the association between the genotypes of IGF-I gene and growth traits in 80 harvest size European sea bass (Dicentrarchus labrax, L.) reared in Izmir region of Turkey. The 821 bp long exon 1 and 5' UTR regions of IGF-I gene were amplified, and PCR products were analyzed via DNA sequencing method. Two novel single nucleotide polymorphisms (SNPs) such as g.46672A > G and g.46749C > T in the 5' UTR region of IGF-I gene in the European sea bass were detected for the first time with this study. Associations between the genotypes of IGF-I g.46749C > T locus and body weight were found statistically significant (p < 0.05). The genotypes of IGF-I g.46749C > T and g.46672A > G loci were found significantly associated with total length (p < 0.05). However, both loci did not show significant associations with body width. The studied gene region sequences were entered to NCBI GenBank database with the accession numbers: MK621680-MK621682. Thus, these polymorphisms have a significant effect on the body weight and total length which could be useful for sea bass selection and breeding for marker-assisted selection (MAS) program.