Skeletal muscle is the most economically valuable tissue in meat-producing animals and enhancing muscle growth in these species may enhance the efficiency of meat production.

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BACKGROUND Myostatin (MSTN) negatively regulates skeletal muscle development; however, its functions in internal organs have not been thoroughly investigated. Here, we compared the morphological, molecular, and biological characteristics of the heart, liver, spleen, lungs, kidneys, and tongue of homozygous MSTN mutant (MSTN−/−), heterozygous MSTN mutant (MSTN+/−), and wild‐type (WT) piglets. RESULTS The heart and liver were lighter in MSTN−/− piglets than in MSTN+/− piglets, while the tongue was heavier in MSTN−/− piglets than in WT piglets (P < 0.05). Furthermore, the tongue was longer in MSTN−/− piglets than in WT piglets, and myofibers of the tongue were significantly larger in the former piglets than in the latter ones (P < 0.01). mRNA expression of MSTN in all organs was significantly lower in MSTN−/− and MSTN+/− piglets than in WT piglets (P < 0.05). Meanwhile, mRNA expression of follistatin, which is closely related to MSTN, in the heart and liver was significantly higher in MSTN−/− piglets than in MSTN+/− and WT piglets (P < 0.05). In addition, protein expression of MSTN in the heart, kidneys, and tongue was significantly lower in MSTN−/− piglets than in WT piglets (P < 0.01). CONCLUSION These results suggest that MSTN is widely expressed and has marked effects in multiple internal organs. Myostatin has crucial functions in regulating internal organ size, especially the tongue. © 2019 Society of Chemical Industry

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Abnormal epigenetic modifications are considered a main contributing factor to low cloning efficiency. In the present study, we explored the effects of quisinostat, a novel histone deacetylase inhibitor, on blastocyst formation rate in porcine somatic-cell nuclear transfer (SCNT) embryos, on acetylation of histone H3 lysine 9 (AcH3K9), and on expression of POU5F1 protein and apoptosis-related genes BAX and BCL2. Our results showed that treatment with 10 nM quisinostat for 24 hr significantly improved the development of reconstructed embryos compared to the untreated group (19.0 ± 1.6% vs. 10.2 ± 0.9%; p < 0.05). Quisinostat-treated SCNT embryos also possessed significantly increased AcH3K9 at the pseudo-pronuclear stage (p < 0.05), as well as improved immunostaining intensity for POU5F1 at the blastocyst stage (p < 0.05). While no statistical difference in BAX expression was observed, BCL2 transcript abundance was significantly different in the quisinostat-treated compared to the untreated control group. Of the 457 quisinostat-treated cloned embryos transferred into three surrogates, six fetuses developed from the one sow that became pregnant. These findings suggested that quisinostat can regulate gene expression and epigenetic modification, facilitating nuclear reprogramming, and subsequently improving the developmental competence of pig SCNT embryos and blastocyst quality.