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N6-Methyladenosine (m6A) RNA modification plays an essential role in many biological processes. To investigate the regulatory role of m6A on the skeletal muscle development in Hu sheep, this study took newborn Hu sheep (b_B Group) and six-month-old Hu sheep (s_B Group) as the objects. MeRIP-seq and RNA-Seq analysis techniques were used to detect differentially methylated genes (DMGs) and differentially expressed genes (DEGs) in the longissimus dorsi muscle of Hu sheep at different months of age. Then, conjoint analysis was further employed to screen for key genes involved in skeletal muscle development that are modified by m6A and expressed by mRNA. According to the results of the MeRIP-seq analysis, there were 285 m6A differentially methylated peaks (DMPs) in total between b_B Group and s_B Group, with 192 significant upregulated peaks and 93 significant downregulated peaks. GO and KEGG analysis revealed that DMGs are mainly enriched in actin-binding, cellular transport, and metabolic pathways. According to the results of the RNA-seq analysis, there were 4,349 DEGs in total between b_B Group and s_B Group, with 2010 upregulated genes and 2,339 downregulated genes. DEGs are found to be mainly enriched in the regulation of actin cytoskeleton tissue, AMPK and FoxO signaling pathways, etc. The conjoint analysis demonstrated that 283 genes were both modified by m6A and expressed by mRNA. Among them, three genes relevant to muscle growth (RGMB, MAPK8IP3, and RSPO3) were selected as candidates for quantitative validation, and the results were in line with the sequencing results. The results mentioned above all suggest that m6A plays a certain role in the skeletal muscle development in Hu sheep.

Background: Rumen epithelium plays a central role in absorbing, transporting, and metabolizing of short-chain fatty acids. For dairy calves, the growth of rumen papillae greatly enhances the rumen surface area to absorb nutrients. However, the molecular mechanism underlying dairy calves rumen postnatal development remains rarely understood.Results: Here, we firstly describe the histological change of rumen epithelium from birth to day 90 of age. Then, a shotgun approach and bioinformatics analyses were used to investigate and compare proteomic profiles of Holstein calve rumen epithelium on day 0, 30, 60 and 90 of age. A total of 4372 proteins were identified, in which we found 852, 342, 164 and 95 differentially expressed proteins between D0 and D30, between D30 and D60, between D60 and D90, respectively. Finally, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to provide a comprehensive proteomic landscape of dairy calves rumen development at tissue level.Conclusion: To conclude, our data indicated that keratinocyte differentiation, mitochondrion formation, the establishment of urea transport and innate immune system play central roles during rumen epithelium development. Tetrahydrobiopterin (BH4) presents an important role in rumen epithelial keratinization. The biological processes of BH4 biosynthesis and molecular function of nicotinamide adenine dinucleotide phosphate binding participate in mitochondrial cristae formation. The proposed datasets provide a useful basis for future studies to better comprehend dairy calves rumen epithelial development.

Background: The development of the rumen epithelium is a critical physiological challenge for sheep. However, the molecular mechanism underlying postnatal rumen development in sheep remains rarely understood.Results: Here, we used a shotgun approach and bioinformatics analyses to investigate and compare proteomic profiles of sheep rumen epithelium tissue on day 0, 15, 30, 45, and 60 of age. A total of 4,523 proteins were identified, in which we found 852, 342, 164, and 95 differentially expressed proteins (DEPs) between day 0 and day 15, between day 15 and day 30, between day 30 and day 45, between day 45 and day 60, respectively. Furthermore, subcellular localization analysis showed that the DEPs were majorly localized in mitochondrion between day 0 and day 15, after which nucleus proteins were the most DEPs. Finally, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that DEPs significantly enriched in mitochondrion, ubiquitination, histone modifications, glutathione synthase activity, and wnt and nortch signaling pathways.Conclusion: Our data indicate that the biogenesis of mitochondrion in rumen epithelial cell is essential for the initiation of rumen epithelial development. Glutathione, wnt signaling pathway and nortch signaling pathway participated in rumen epithelial growth. Ubiquitination, post-translational modifications of histone might be key molecular functions in regulating rumen epithelial development.

Body size is an important indicator of growth and health in sheep. In the present study, we performed Genome-Wide Association Studies (GWAS) to detect significant single-nucleotide polymorphisms (SNPs) associated with Hu sheep’s body size. After genotyping parental (G1) and offspring (G2) generation of the nucleus herd for meat production of Hu sheep and conducting GWAS on the body height, chest circumference, body length, tail length, and tail width of the two groups, 5 SNPs associated with body height and 4 SNPs correlated with chest circumference were identified at the chromosomal significance level. No SNPs were significantly correlated to body length, tail length, and width. Four out of the 9 SNPs were found to be located within the 4 genes. KITLG and CADM2 are considered as candidate functional genes related to body height; MCTP1 and COL4A6 are candidate functional genes related to chest circumference. The 9 SNPs found in GWAS were verified using the G3 generation of the nucleus herd for meat production. Nine products were amplified around the 9 sites, and 29 SNPs were found; 3 mutation sites, G > C mutation at 134 bp downstream of s554331, T > G mutation at 19 bp upstream of s26859.1, and A > G mutation at 81 bp downstream of s26859.1, were significantly correlated to the body height. Dual-luciferase reporter gene experiments showed that the 3 SNPs could significantly impact dual-luciferase and gene transcription activity.

Body weight (BW) is a critical economic trait for meat production in sheep. The current study aimed to perform a genome-wide association study (GWAS) to detect significant single-nucleotide polymorphisms (SNPs) that are associated with BW in Hu sheep. The comparison and analysis of the G1 and G2 generations of a nucleus meat Hu sheep breeding herd revealed four SNPs identified by GWAS. The subsequent verification of the significant SNP loci in the Hu sheep G3 generation nucleus herd also detected nine SNPs in significant SNP regions. Two SNPs were significantly associated with the BW of Hu sheep (p < 0.05). OARX_76354330.1 and s64890.1 could be identified as functional SNPs for the growth traits of Hu sheep. CAPN6, as a candidate gene, was significantly different in the biceps femoris and longissimus dorsi muscles of weaning (60-day) and 6-month sheep, which facilitated the discovery of causal variants for BW and contributed to the marker-assisted selection breeding of Hu sheep.