Abstract
Myostatin (MSTN) gene is a negative regulator of skeletal muscle. In this study, we try to evaluate MSTN as a candidate gene for a marker assisted selection in Nile tilapia growth trait. Molecular characterization of MSTN gene was done using seven designed primers. We demonstrated that, O. niloticus MSTN sequence and its promoter is as for all known vertebrates. Novel SNPs were identified in coding and non-coding regions compared with MSTN gene of O. niloticus x O. aureus hybrid, three non-synonymous SNPs were found at MSTN coding region; two at exon one 369 C>A, 831 T>A, and one at exon 3 2637 G>A, altering Thr 38-Pro, Glu 121-Val and Tyr 375-Cys respectively. Phylogenetic analysis revealed high similarity (99.2) with MSTN gene of the hybrid with O. aurous. BsmI induced cutting pattern at MSTN-exon 2 (607-bp). Among two hundred monosex male fish, two different genotypes were reported; AB genotype (607-bp, 507-bp and 100-bp) and BB genotype (507-bp and 100-bp fragments), were produced. Most large-size fish are included in AB genotype with 0.8 frequency and significantly increased body weight compared with small size fish, which are mostly included in BB genotype with 0.9 frequencies. Novel BsmI-exon 2 polymorphism of MSTN gene can be used as a marker assisted selection for large body weight in heterozygous Nile tilapia fish.
Highlights
Nile tilapia, a wide spread teleost fish in developing countries, is considered the second most important farmed fresh water fish
Fish breeding for fast-growing strains through genetic selection will in turn give considerable scope for rapid development of this aquaculture industry, so the aim of this study was to characterization of Nile tilapia MSTN gene, detecting SNPs and performing genetic association studies between MSTN polymorphisms and growth traits in Nile tilapia using PCR-RFLPs
Compared with MSTN gene of O. niloticus x O. aureus hybrid, we demonstrated novel four SNPs at 5'UTR, one SNP at intron 2, two SNPs at 3'UTR and three non-synonymous SNPs at the coding regions
Summary
A wide spread teleost fish in developing countries, is considered the second most important farmed fresh water fish. Manipulating genes that control muscle mass in fish such as Myostatin (MSTN) gene will directly lead to improved growth rates. Mutations in the MSTN gene were shown to cause the doublemuscling phenotype in many mammalian species [2]. MSTN homologs have been cloned and characterized in a large number of fish species [3, 4, 5, 6]. Comparison of MSTN sequences revealed that it was extremely well conserved throughout evolution. Fish MSTN are over 85% identical to the mammalian homologue in the C-Terminal region. The high sequence identity suggests that this gene plays a similar role in regulating muscle growth in non-mammalian vertebrates [2, 8]
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