Characterization of a myostatin gene (MSTN1) from spotted halibut (Verasper variegatus) and association between its promoter polymorphism and individual growth performance

Non-Additive and Asymmetric Allelic Expression of p38 mapk in Hybrid Tilapia (Oreochromis niloticus ♀ × O. aureus ♂)

Hybridization is a widely used breeding technique in fish species that enhances desirable traits in cultured species through heterosis. However, the mechanism by which hybrids alter gene expression to form heterosis remains unclear. In this study, a group of hybrid tilapia was used to elucidate heterosis through interspecies crossing. Specifically, p38 was analyzed to describe the regulation of gene expression variation in hybrid tilapia. Transcripts from the Nile tilapia allele were found to be significantly higher than those from the blue tilapia allele in hybrid individuals, indicating that the expression of p38 was dominated by Nile tilapia sub-genomic alleles. The study also found a compensatory interaction of cis- and trans-acting elements of the Nile tilapia and blue tilapia sub-genomes, inducing a non-additive expression of p38 in hybrids. Eight specific SNPs were identified in the p38 promoter regions of Nile tilapia and blue tilapia, and were found to be promoter differences leading to differences in gene expression efficiencies between parental alleles using a dual-luciferase reporter system. This study provides insights into the non-additive expression patterns of key functional genes in fish hybrids related to growth and immunity response.

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-β (TGF-β) 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.

Dietary Antioxidant Supplementation Promotes Growth in Senegalese Sole Postlarvae

Somatic growth is a balance between protein synthesis and degradation, and it is largely influenced by nutritional clues. Antioxidants levels play a key role in protein turnover by reducing the oxidative damage in the skeletal muscle, and hence promoting growth performance in the long-term. In the present study, Senegalese sole postlarvae (45 days after hatching, DAH) were fed with three experimental diets, a control (CTRL) and two supplemented with natural antioxidants: curcumin (CC) and grape seed (GS). Trial spanned for 25 days and growth performance, muscle cellularity and the expression of muscle growth related genes were assessed at the end of the experiment (70 DAH). The diets CC and GS significantly improved growth performance of fish compared to the CTRL diet. This enhanced growth was associated with larger muscle cross sectional area, with fish fed CC being significantly different from those fed the CTRL. Sole fed the CC diet had the highest number of muscle fibers, indicating that this diet promoted muscle hyperplastic growth. Although the mean fiber diameter did not differ significantly amongst treatments, the proportion of large-sized fibers (>25 μm) was also higher in fish fed the CC diet suggesting increased hypertrophic growth. Such differences in the phenotype were associated with a significant up-regulation of the myogenic differentiation 2 (myod2) and the myomaker (mymk) transcripts involved in myocyte differentiation and fusion, respectively, during larval development. The inclusion of grape seed extract (GS diet) resulted in a significant increase in the expression of myostatin1. These results demonstrate that both diets (CC and GS) can positively modulate muscle development and promote growth in sole postlarvae. This effect is more prominent in CC fed fish, where increased hyperplastic and hypertrophic growth of the muscle was associated with an upregulation of myod2 and mymk genes.

Myostatin gene promoter: structure, conservation and importance as a target for muscle modulation

Myostatin (MSTN) is one of the key factors regulating myogenesis. Because of its role as a negative regulator of muscle mass deposition, much interest has been given to its protein and, in recent years, several studies have analysed MSTN gene regulation. This review discusses the MSTN gene promoter, focusing on its structure in several animal species, both vertebrate and invertebrate. We report the important binding sites considering their degree of phylogenetic conservation and roles they play in the promoter activity. Finally, we discuss recent studies focusing on MSTN gene regulation via promoter manipulation and the potential applications they have both in medicine and agriculture.

Association between expression levels and growth trait-related SNPs located in promoters of the MC4R and MSTN genes in Spinibarbus hollandi

Melanocortin 4 receptor: (MC4R) and Myostatin (MSTN) are two important growth trait-related genes in animals. In this study, we showed that two SNPs, MC4R-719A>G and MSTN-519C>T, found in the promoters of the MC4R and MSTN genes, respectively, are both associated with growth traits in Spinibarbus hollandi. Furthermore, we observed that there were significant associations between the expression levels of the MC4R and MSTN genes and these two growth trait-related SNPs. The expression level of MC4R gene in brain was lower in GG genotype fish with extremely high growth performance than that in AA genotype fish with extremely low growth performance. Expression level of the MSTN gene in muscle was lower in TT genotype fish with extremely high growth performance than that in CC and CT genotype fish with lower growth performance. The results indicated that these SNPs located in the promoters of MC4R and MSTN are associated with growth-related traits through modification of gene expression levels. The MSTN and MC4R SNPs may have useful application in effective marker-assisted selection aimed to increase output in S. hollandi.

The effects of exogenous cortisol on myostatin transcription in rainbow trout, Oncorhynchus mykiss

Glucocorticoids (GCs) strongly regulate myostatin expression in mammals via glucocorticoid response elements (GREs), and bioinformatics methods suggest that this regulatory mechanism is conserved among many vertebrates. However, the multiple myostatin genes found in some fishes may be an exception. In silico promoter analyses of the three putative rainbow trout (Oncorhynchus mykiss) myostatin promoters have failed to identify putative GREs, suggesting a divergence in myostatin function. Therefore, we hypothesized that myostatin mRNA expression is not regulated by glucocorticoids in rainbow trout. In this study, both juvenile rainbow trout and primary trout myoblasts were treated with cortisol to examine the effects on myostatin mRNA expression. Results suggest that exogenous cortisol does not regulate myostatin-1a and -1b expression in vivo, as myostatin mRNA levels were not significantly affected by cortisol treatment in either red or white muscle tissue. In red muscle, myostatin-2a levels were significantly elevated in the cortisol treatment group relative to the control, but not the vehicle control, at both 12 h and 24 h post-injection. As such, it is unclear if cortisol was acting alone or in combination with the vehicle. Cortisol increased myostatin-1b expression in a dose-dependent manner in vitro. Further work is needed to determine if this response is the direct result of cortisol acting on the myostatin-1b promoter or through an alternative mechanism. These results suggest that regulation of myostatin by cortisol may not be as highly conserved as previously thought and support previous work that describes potential functional divergence of the multiple myostatin genes in fishes.

The myostatin gene of Mytilus chilensis evidences a high level of polymorphism and ubiquitous transcript expression

Myostatin (MSTN) is a protein of the Transforming Growth Factor-β (TGF-β) superfamily and plays a crucial role in muscular development for higher vertebrates. However, its biological function in marine invertebrates remains undiscovered. This study characterizes the full-length sequence of the Mytilus chilensis myostatin gene (Mc-MSTN). Furthermore, tissue transcription patterns and putative single nucleotide polymorphisms (SNPs) were also identified. The Mc-MSTN cDNA sequence showed 3528 base pairs (bp), consisting of 161 bp of 5' UTR, 2,110 bp of 3' UTR, and an open reading frame of 1,257 bp encoding for 418 amino acids and with an RXXR proteolytic site and nine cysteine-conserved residues. Gene transcription analysis revealed that the Mc-MSTN has ubiquitous expression among several tissues, with higher expression in the gonads and mantle than in the digestive gland, gills, and hemolymph. Furthermore, high levels of polymorphisms were detected (28 SNPs in 3'-UTR and 9 SNPs in the coding region). Two SNPs were non-synonymous and involved amino acid changes between Glu/Asp and Thr/Ile. Until now, the MSTN gene has been mainly related to muscle growth in marine bivalves. However, the present study suggests a putative biological function not entirely associated to muscle tissue and contributes molecular evidence to the current debate about the function of the MSTN gene in marine invertebrates.

A SNP in the 5' flanking region of the myostatin-1b gene is associated with harvest traits in Atlantic salmon (Salmo salar)

Background

Myostatin (MSTN) belongs to the transforming growth factor-β superfamily and is a potent negative regulator of skeletal muscle development and growth in mammals. Most teleost fish possess two MSTN paralogues. However, as a consequence of a recent whole genome-duplication event, salmonids have four: MSTN-1 (−1a and -1b) and MSTN-2 (−2a and -2b). Evidence suggests that teleost MSTN plays a role in the regulation of muscle growth. In the current study, the MSTN-1b gene was re-sequenced and screened for SNP markers in a commercial population of Atlantic salmon. After genotyping 4,800 progeny for the discovered SNPs, we investigated their association with eight harvest traits - four body-weight traits, two ratios of weight traits, flesh colour and fat percentage - using a mixed model association analysis.

Results

Three novel SNPs were discovered in the MSTN-1b gene of Atlantic salmon. One of the SNPs, located within the 5′ flanking region (g.1086C > T), had a significant association with harvest traits (p < 0.05), specifically for: Harvest Weight (kg), Gutted Weight (kg), Deheaded Weight (kg) and Fillet Weight (kg). The haplotype-based association analysis was consistent with this result because the two haplotypes that showed a significant association with body-weight traits, hap4 and hap5 (p < 0.05 and p < 0.01, respectively), differ by a single substitution at the g.1086C > T locus. The alleles at g.1086C > T act in an additive manner and explain a small percentage of the genetic variation of these phenotypes.

Conclusions

The association analysis revealed that g.1086C > T had a significant association with all body-weight traits under study. Although the SNP explains a small percentage of the variance, our results indicate that a variation in the 5′ flanking region of the myostatin gene is associated with the genetic regulation of growth in Atlantic salmon.

Development of molecular resources for an intertidal clam, Sinonovacula constricta, using 454 transcriptome sequencing

Background

The razor clam Sinonovacula constricta is a benthic intertidal bivalve species with important commercial value. Despite its economic importance, knowledge of its transcriptome is scarce. Next generation sequencing technologies offer rapid and efficient tools for generating large numbers of sequences, which can be used to characterize the transcriptome, to develop effective molecular markers and to identify genes associated with growth, a key breeding trait.

Results

Total RNA was isolated from the mantle, gill, liver, siphon, gonad and muscular foot tissues. High-throughput deep sequencing of S. constricta using 454 pyrosequencing technology yielded 859,313 high-quality reads with an average read length of 489 bp. Clustering and assembly of these reads produced 16,323 contigs and 131,346 singletons with average lengths of 1,376 bp and 458 bp, respectively. Based on transcriptome sequencing, 14,615 sequences had significant matches with known genes encoding 147,669 predicted proteins. Subsequently, previously unknown growth-related genes were identified. A total of 13,563 microsatellites (SSRs) and 13,634 high-confidence single nucleotide polymorphism loci (SNPs) were discovered, of which almost half were validated.

Conclusion

De novo sequencing of the razor clam S. constricta transcriptome on the 454 GS FLX platform generated a large number of ESTs. Candidate growth factors and a large number of SSRs and SNPs were identified. These results will impact genetic studies of S. constricta.