The gut microbiota affects the metabolism, health and growth rate of pigs. Understanding the characteristics of gut microbiota of different pig breeds at each growth stage will enable the design of individualized feeding strategies. The present study aimed to compare the growth curves and development patterns of pigs of three different breeds (Duroc, Landrace and Yorkshire) using the mathematical models Gompertz, Logistic, Von Bertalanffy and Richards. For Duroc pigs, the Gompertz model showed the highest prediction accuracy (R² = 0.9974). In contrast, the best models for Landrace and Yorkshire pigs were Richards (R² = 0.9986) and Von Bertalanffy (R² = 0.9977), respectively. Path analysis showed that body length (path coefficient = 0.507) and chest circumference (path coefficient = 0.532) contributed more significantly to the body weight of pigs at the early growth stage, while hip circumference (path coefficient = 0.312) had a greater influence on pig body weight in the late growth stage. Moreover, the composition of the gut microbiota of pigs at two growth stages (60 kg of body weight in the early growth stage and 120 kg in the finishing stage) was studied using 16S rRNA sequencing technology. Variations in gut microbiota composition of pigs at different growth stages were observed. KEGG pathway enrichment analysis of annotated metagenomes revealed that protein synthesis and amino acid metabolism pathways were significantly enriched in pigs at the early growth stage, which may be related to nutritional requirements of pigs during this stage. This study confirmed longitudinal variation in the gut microbiota of pigs pertaining to age as well as lateral variation related to pig breed. The present findings expand the current understanding of the variations in swine gut microbiota during production stages.

Skeletal muscle atrophy is a complex degenerative disease characterized by decreased skeletal muscle mass, skeletal muscle strength, and function. MicroRNAs (miRNAs) are a potential therapeutic target, and natural products that regulate miRNA expression may be a safe and effective treatment strategy for muscle atrophy. Previous studies have shown beneficial effects of genistein treatment on muscle mass and muscle atrophy, but the mechanism is not fully understood. Differential co-expression network analysis revealed that miR-222 was upregulated in multiple skeletal muscle atrophy models. Subsequent in vitro (C2C12 myoblasts) and in vivo (C57BL/6 mice) experiments showed that genistein could alleviate dexamethasone-induced muscle atrophy and downregulate the expression of miR-222 in muscle tissue and C2C12 myotubes. The dual-luciferase reporter assay system confirmed that IGF1 is a target gene of miR-222 and is regulated by genistein. In C2C12 myotubes, both dexamethasone and miR-222 overexpression promoted muscle atrophy, however, this function was significantly reduced after genistein treatment. Furthermore, we also observed that both genistein and miR-222 antagomiR could significantly inhibit dexamethasone-induced muscle atrophy in vivo. These results suggest that miR-222 may be involved in the regulation of genistein on muscle atrophy, and genistein and miR-222 may be used to improve muscle health.

Intrauterine growth restriction (IUGR) is an important cause of newborn morbidity and mortality in mammals. Transfer RNA-derived small RNA (tsRNA) has become an emerging non-coding RNA in recent years. tsRNA and microRNAs (miRNAs) share similar mechanisms, which are involved in various biological processes. In this study, the pig was used as a model of IUGR, and the tsRNA and miRNA expression profile in the spleen was characterized by RNA sequencing. A total of 361 miRNAs and 620 tsRNAs were identified, of which 22 were differentially expressed miRNA (DEM) and 25 differentially expressed tsRNA (DET). tRF-5c were the primary tsRNA type making up more than 90%, and the most abundantly expressed tsRNAs are from tRNA-Gly-GCC. Functional enrichment analysis found that those DETs and DEMs have been implicated in the immune system process. Protein–protein interaction (PPI) network analysis revealed ssc-miR-370, ssc-miR-206, tiRNA-Ser-TGA-001 and tRF-Val-AAC-034 could be major regulators. TNF, TLR4, CD44, MAPK1 and STAT1 were predicted hub target genes. Those DETs and DEMs may regulate the T-cell receptor signaling pathway and Toll-like receptor signaling pathway to mediate the immunocompromise caused by IUGR. The results discussed in this article uncover the potential role of tsRNAs and miRNAs in IUGR porcine spleen.

Genistein (GEN), a phytoestrogen, has been reported to regulate skeletal muscle endocrine factor expression and muscle fiber type switching, but its role in skeletal muscle regeneration is poorly understood. As a class of epigenetic regulators widely involved in skeletal muscle development, microRNAs (miRNAs) have the potential to treat skeletal muscle injury. In this study, we identified miR-221 and miR-222 and their target genes MyoG and Tnnc1 as key regulators during skeletal muscle regeneration, and both were regulated by GEN. C2C12 myoblasts and C2C12 myotubes were then used to simulate the proliferation and differentiation of muscle satellite cells during skeletal muscle regeneration. The results showed that GEN could inhibit the proliferation of satellite cells and promote the differentiation of satellite cells by inhibiting the expression of miR-221/222. Subsequent in vitro and in vivo experiments showed that GEN improved skeletal muscle regeneration mainly by promoting satellite cell differentiation in the middle and late stages, by regulating miR-221/222 expression. These results suggest that miR-221/222 and their natural regulator GEN have potential applications in skeletal muscle regeneration.