Polymorphisms in a myostatin gene and associations with growth in a hybrid of Culter alburnus and Ancherythroculter nigrocauda

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.

Comparative analysis of growth performance and liver transcriptome response of juvenile Ancherythroculter nigrocauda fed diets with different protein levels

This study aimed at investigating the effects of dietary protein levels on the growth and liver transcriptome in juvenile Ancherythroculter nigrocauda. Six semi-purified diets were formulated containing 25 (control), 30, 35, 40, 45, and 50% protein. Each diet was fed to three groups of 35 fish (mean initial weight: 5.86 ± 0.10 g) for 56 days. The rate of weight gain and specific growth rate increased with dietary protein levels from 25% to 40%, but remained unchanged when fed with 45 or 50% dietary protein. The feed conversion ratio was significantly influenced by the dietary protein levels, being the lowest in fish fed 40% protein. Illumina RNA-seq analysis was performed to investigate liver gene expression changes under different dietary protein treatments. A total of 367.78 million clean reads were obtained from the six libraries. Compared with 25% protein treatment library, there were 734, 1946, 1755, 2726, and 1523 upregulated genes, and 407, 1882, 1865, 2216 and 1624 downregulated genes in the 30, 35, 40, 45, and 50% protein treatment libraries, respectively. Trend analysis of these differentially expressed genes (DEGs) identified six statistically significant trends. A series of DEGs that related to protein metabolism, growth and development, lipid metabolism and immune and stress response were identified. Moreover, gene ontology enrichment analysis of the DEGs demonstrated that cellular process, single-organism process, metabolic process and biological regulation were the most highly overrepresented biological processes. Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed that protein processing in endoplasmic reticulum, PPAR signaling pathway, complement and coagulation cascades, and cytochrome P450 (CYP450s) were significantly enriched in the dietary protein treatment groups. Furthermore, qPCR results showed excellent agreement on those of RNA-seq for both up- and down-regulated genes (including fasn, accα, SCD, CPT-I, igf1, ST, AST, trdmt1, hsp70, cyp450, MHC-II, C4, tgfβ, ube4b, apoE and abcb7). Thus, our results provide the baseline information for the feed formulation and nutritional research for A. nigrocauda.