Domestic goats are commonly reared for meat and milk production in several regions of the world. However, the genetic mechanism underlying muscle development and meat quality of goats is limited. Therefore, the aim of this study was to identify known and novel genes regulating muscle development and meat quality of goats using second- and third-generation sequencing technologies. To achieve this, the meat quality and transcriptomes of longissimus dorsi (LD) and biceps femoris (BF) muscle tissues of Lingqiu Greyback goats were examined and compared. Differentially expressed genes (DEGs) and isoforms (DEIs) were functionally annotated. Results showed that 45,574 full-length transcripts covering 18,491 loci were characterized, and 12,566 genes were co-expressed in all samples. Differential expression analysis identified 231 DEGs, including 45 novel genes in the LD and BF muscles of the goats. Additionally, 1173 DEIs were found, in which 642 novel isoforms were identified in this study. Functional annotation and pathway analysis of the DEGs and DEIs revealed that some of them were associated with muscle growth and lipid metabolism. Overall, the findings of this study contribute to the understanding of the transcriptomic diversity underlying meat quality and muscle development of goat.

The QKI genes encode RNA-binding proteins regulating cell proliferation, differentiation, and apoptosis. The Goat QKI has six isoforms, but their roles in myogenesis are unclear. In this study, the six isoforms of the QKI gene were overexpressed in goat myoblast. Immunofluorescence, qPCR and Western blot were used to evaluate the effect of QKI on the differentiation of goat myoblast. An RNA-Seq was performed on the cells with the gain of the function from the major isoforms to screen differentially expressed genes (DEGs). The results show that six isoforms had different degrees of deletion in exons 6 and 7, and caused the appearance of different types of encoded amino acids. The expression levels of the QKI-1 and QKI-5 groups were upregulated in the biceps femoris and latissimus dorsi muscle tissues compared with those of the QKI-4, QKI-7, QKI-3 and QKI-6 groups. After 6 d of myoblast differentiation, QKI-5 and the myogenic differentiators MyoG, MyoD, and MyHC were upregulated. Compared to the negative control group, QKI promoted myotube differentiation and the myoblasts overexpressing QKI-5 formed large, abundant myotubes. In summary, we identified that the overexpression of the QKI gene promotes goat-myoblast differentiation and that QKI-5 is the major isoform, with a key role. The RNA-Seq screened 76 upregulated and 123 downregulated DEGs between the negative control and the QKI-5-overexpressing goat myoblasts after d 6 of differentiation. The GO and KEGG analyses associated the downregulated DEGs with muscle-related biological functions. Only the pathways related to muscle growth and development were enriched. This study provides a theoretical basis for further exploring the regulatory mechanism of QKI in skeletal-muscle development in goats.

Follicular atresia is mainly driven by the oxidative stress-induced apoptosis of granulosa cells (GCs). Oxidative stress mediated by H₂O₂ is the predominant form of stress in cells and plays a key role in the death of porcine GCs. In the present study, using integrated transcriptomic and untargeted metabolomic approaches, we explored the mechanisms underlying the regulation of oxidative stress in porcine follicular GCs. Per the transcriptomic analysis, compared with the control group, we identified 328 differentially expressed mRNAs (260 upregulated, 68 downregulated) in the H₂O₂-treatment group; these mRNAs were significantly enriched in apoptosis-related pathways, including the tumour necrosis factor (TNF) and p53 signalling pathways. Furthermore, via untargeted metabolomic analysis, we identified 150 differentially expressed metabolites (101 positive, 49 negative). The pathways associated with protein digestion and absorption, glycine, serine, and threonine metabolism, amino acid biosynthesis, and carbon metabolism were enriched with these metabolites. The integrated transcriptomic and metabolomic analyses revealed taurine, creatine, L-serine, and hypoxanthine as the key metabolites under H₂O₂-induced oxidative stress. Both the differential genes and metabolites were notably enriched in the FOXO and mineral absorption pathways. In the present study, we elucidated the regulatory mechanism underlying H₂O₂-induced oxidative stress in porcine follicular GCs via transcriptomic and metabolomic analyses. Our findings offer novel insights into the alleviation of oxidative stress in GCs.