Spermatogenesis in mammalian testes is essential for male fertility, ensuring a continuous supply of mature sperm. The testicular microenvironment finely tunes this process, with retinoic acid, an active metabolite of vitamin A, serving a pivotal role. Retinoic acid is critical for various stages, including the differentiation of spermatogonia, meiosis in spermatogenic cells, and the production of mature spermatozoa. Vitamin A deficiency halts spermatogenesis, leading to the degeneration of numerous germ cells, a condition reversible with retinoic acid supplementation. Although retinoic acid can restore fertility in some males with reproductive disorders, it does not work universally. Furthermore, high doses may adversely affect reproduction. The inconsistent outcomes of retinoid treatments in addressing infertility are linked to the incomplete understanding of the molecular mechanisms through which retinoid signaling governs spermatogenesis. In addition to the treatment of male reproductive disorders, the role of retinoic acid in spermatogenesis also provides new ideas for the development of male non-hormone contraceptives. This paper will explore three facets: the synthesis and breakdown of retinoic acid in the testes, its role in spermatogenesis, and its application in male reproduction. Our discussion aims to provide a comprehensive reference for studying the regulatory effects of retinoic acid signaling on spermatogenesis and offer insights into its use in treating male reproductive issues.

Improving growth while preserving breed-defining characteristics is a central challenge in indigenous livestock breeding. We addressed this issue in Jining Grey goats using low-depth whole-genome sequencing and a conservative multi-evidence marker-prioritization framework. The discovery cohort included 70 performance-graded goats at 3 months (n = 37) and 6 months (n = 33; mean depth, 2.07×), and 47 seven-day-old goats from the same project were used for exploratory early-life trend analysis (mean depth, 2.10×). After site-level filtering, phasing, and within-cohort imputation, masking-based assessment of 120,000 genotype cells yielded 94.38% exact genotype concordance and a hard-dosage correlation of 0.919. Performance grading captured consistent differences in body weight and body-size traits, but the small 3-month Conventional group required conservative interpretation. Selective-sweep analyses highlighted breed-background regions, including signals near KIT, whereas GWAS and superior-genotype comparisons prioritized candidate growth loci, including chr10:78518687 for six-month chest girth and literature-supported genes involved in muscle growth and developmental regulation. Overlap and permutation analyses indicated limited physical overlap between growth-prioritized loci and major selective-sweep regions. A 99-SNP candidate panel showed exploratory prediction potential (maximum cross-validated r ≈ 0.47), whereas seven-day analyses showed only nominal trends without FDR significance. These findings provide a preliminary marker resource for future Jining Grey goat breeding and conservation, pending external validation, denser genotyping, and functional confirmation.

Myostatin (MSTN) is a well-established negative regulator of skeletal muscle growth; however, its role in bone metabolism and osteogenic differentiation remains incompletely understood. In this study, untargeted and targeted metabolomic analyses were performed to investigate the metabolic effects of the MSTN^Del73C mutation during osteogenic differentiation of sheep bone marrow mesenchymal stem cells (BMSCs). Metabolomic profiles were analyzed in wild-type and MSTN^Del73C mutant BMSCs at 0, 7, and 14 days of osteogenic induction. During normal osteogenic differentiation, metabolites related to glycerophospholipid metabolism were repeatedly detected among significantly altered features, accompanied by marked increases in multiple lysophospholipid subclasses, including lysophosphatidylcholine (LPC), lysophosphatidylserine (LPS), and lysophosphatidylinositol (LPI). In contrast, MSTN^Del73C mutation was associated with significant reductions in several LPC and LPI species (p < 0.01 or p < 0.001), suggesting altered lipid metabolic profiles during differentiation. Targeted metabolomic validation further confirmed the altered abundance pattern of LPC 18:2. Collectively, these findings suggest that MSTN mutation is closely associated with metabolic remodeling during osteogenic differentiation and suggest potential involvement of glycerophospholipid-related metabolites involved in MSTN-related regulation of sheep BMSC osteogenesis.

Crossbreeding indigenous goats with exotic meat breeds is a common strategy to improve production performance, but its combined effects on growth and reproductive traits and the potential contribution of the gut microbiota have not been systematically evaluated in Chinese goat populations. This study used high-prolific Jining Grey (JJ) does mated with Nubian (N) bucks to establish three genetic groups: purebred Jining Grey (JJ), F1 Nubian × Jining Grey (NJ), and backcross offspring (Nubian × (Nubian × Jining Grey); NJJ). Body weight from birth to 12 months and average daily gain were recorded, reproductive traits (lambing rate, litter size, and kid survival) of primiparous and multiparous does were analyzed, and litter total birth weight and weaning weight per lambing were calculated. Fecal samples from JJ and NJJ goats were subjected to 16S rRNA gene sequencing to characterize gut bacterial communities. Body weight differed significantly among the three genetic groups at all ages (p < 0.01). Crossbred kids (NJ and NJJ) were about 30% heavier at birth and showed higher body weight and average daily gain during pre- and post-weaning periods than JJ kids (p < 0.05), representing a consistent growth advantage. In contrast, lambing rate, litter size and kid survival did not differ among genotypes (p > 0.05), whereas litter total birth weight and weaning weight were higher in crossbred than in purebred does (p < 0.05). Alpha-diversity indices were similar between JJ and NJJ goats (p > 0.05), but community structure was significantly distinct (PERMANOVA, p = 0.001), characterized by an increased Firmicutes-to-Bacteroidota ratio and shifts in several energy metabolism-related genera (p < 0.05). In conclusion, introgression of Nubian genetics into Jining Grey goats improves growth performance and litter weight while maintaining high prolificacy; these improvements are accompanied by a restructured gut microbiota that is associated with these growth patterns.