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Low-temperature injury is one of the most significant causes of livestock damage worldwide. To identify genes that respond to cold stress, the transcriptome profile of the skeletal muscle of the Min pig (Sus scrofa) after cold stress was analysed using the deep sequencing technique. One group was raised in the normal environment (18 ± 2°C,n = 3) as the thermos-neutral group; another group was raised in the low-temperature environment (4 ± 2°C,n = 3) as the cold stress group. After 24 h, the gene expression profile of skeletal muscle was analysed. The results showed that the expression levels of 662 genes were significantly up-regulated, and those of 1058 genes were significantly down-regulated in the thermos-neutral and the cold stress groups (P < 0.01). It was found through Gene Ontology analysis that the significantly differently expressed genes were mainly distributed in the cytoplasm, mitochondrion, organelle envelope and ribosomal subunit. They enriched ribosome, fatty acid metabolism, RNA transport and metabolic pathways. It means that cold stress could significantly change the gene expression profile of pig muscle. [ABSTRACT FROM PUBLISHER]

The in vitro maturation (IVM) efficiency of porcine embryos is still low because of poor oocyte quality. Although brilliant cresyl blue positive (BCB+) oocytes with low glucose-6-phosphate dehydrogenase (G6PDH) activity have shown superior quality than BCB negative (-) oocytes with high G6PDH activity, the use of a BCB staining test before IVM is still controversial. This study aimed to shed more light on the subcellular characteristics of porcine oocytes after selection using BCB staining. We assessed germinal vesicle chromatin configuration, cortical granule (CG) migration, mitochondrial distribution, the levels of acetylated lysine 9 of histone H3 (AcH3K9) and nuclear apoptosis features to investigate the correlation between G6PDH activity and these developmentally related features. A pattern of chromatin surrounding the nucleoli was seen in 53.0% of BCB+ oocytes and 77.6% of BCB+ oocytes showed peripherally distributed CGs. After IVM, 48.7% of BCB+ oocytes had a diffused mitochondrial distribution pattern. However, there were no significant differences in the levels of AcH3K9 in the nuclei of blastocysts derived from BCB+ and BCB- oocytes; at the same time, we observed a similar incidence of apoptosis in the BCB+ and control groups. Although this study indicated that G6PDH activity in porcine oocytes was correlated with several subcellular characteristics such as germinal vesicle chromatin configuration, CG migration and mitochondrial distribution, other features such as AcH3K9 level and nuclear apoptotic features were not associated with G6PDH activity and did not validate the BCB staining test. In using this test for selecting porcine oocytes, subcellular characteristics such as the AcH3K9 level and apoptotic nuclear features should also be considered. Adding histone deacetylase inhibitors or apoptosis inhibitors into the culture medium used might improve the efficiency of IVM of BCB+ oocytes. [ABSTRACT FROM AUTHOR]