An alternative vaccine design approach and diagnostic kits are highly required against the anticipated pandemicity caused by the South African Territories type 2 (SAT2) Foot and Mouth Disease Virus (FMDV). However, the distinct antigenicity and immunogenicity of VP1, VP0, and VP3 of FMDV serotype SAT2 are poorly understood. Similarly, the particular roles of the three structural proteins in novel vaccine design and development remain unexplained. We therefore constructed VP1, VP0, and VP3 encoding gene (SAT2:JX014256 strain) separately fused with His-SUMO (histidine-small ubiquitin-related modifier) inserted into pET-32a cassette to express the three recombinant proteins and separately evaluated their antigenicity and immunogenicity in mice. The fusion protein was successfully expressed and purified by the Ni-NTA resin chromatography. The level of serum antibody, spleen lymphocyte proliferation, and cytokines against the three distinct recombinant proteins were analyzed. Results showed that the anti-FMDV humoral response was triggered by these proteins, and the fusion proteins did enhance the splenocyte immune response in the separately immunized mice. We observed low variations among the three fusion proteins in terms of the antibody and cytokine production in mice. Hence, in this study, results demonstrated that the structural proteins of SAT2 FMDV could be used for the development of immunodiagnostic kits and subunit vaccine designs.

Yaks are an ideal model for investigating mammalian adaptation to high-altitude hypoxia; however, the underlying adaptive mechanisms remain unclear. Therefore, this study aimed to investigate the mechanisms underlying yak adaptation to high altitudes, focusing on the role of the PINK1/Parkin pathway. In particular, we established normoxic and hypoxic models of yak skeletal muscle satellite cells (SMSCs). In addition, we examined the relationship between PINK1/Parkin-mediated mitophagy and the activities of key enzymes involved in mitochondrial energy metabolism. At the tissue level, an increase in altitude significantly decreased p62 expression and upregulated LC3B-II expression. Notably, mitophagy levels and the expression of PINK1 and Parkin in the skeletal muscle, lungs, and myocardial tissues increased with altitude. At the cellular level, hypoxia markedly elevated the expression of PINK1 and Parkin proteins in SMSCs, induced the conversion of LC3-I to LC3-II, decreased p62 accumulation, significantly increased the number of autolysosomes, and enhanced autophagic flux. Hypoxia altered mitochondrial electron transport chain function, resulting in compensatory elevation of key enzyme activities in the mitochondrial respiratory chain. However, 3-methyladenine (3-MA) treatment reversed these hypoxia-induced changes. In conclusion, yak SMSCs sustain mitochondrial functional homeostasis under hypoxia via PINK1/Parkin-mediated mitophagy, effectively managing hypoxic stress.

Yaks (Bos grunniens) are a typical species inhabiting high-altitude environments; however, their molecular responses to hypoxic conditions remain incompletely understood. This study aimed to investigate associations among alanyl-transfer RNA synthetase 2 (AARS2) expression, lactylation of pyruvate dehydrogenase E1 alpha 1 (PDHA1) and carnitine palmitoyltransferase 2 (CPT2), and energy metabolism under hypoxic conditions in yaks. Oxygen-sensitive tissues (skeletal muscle, cardiac muscle, and lungs) collected from yaks at different altitudes, along with primary yak skeletal muscle cells, were analyzed using RT-qPCR, Western blotting, immunofluorescence (IF), and co-immunoprecipitation (co-IP). In tissues from the three altitude groups, AARS2 expression was higher in the higher-altitude groups (p < 0.05), whereas PDHA1 and CPT2 expression was lower (p < 0.01). Overall protein lactylation levels were also higher in tissues from the higher-altitude groups. Under hypoxic conditions, lactate levels and AARS2 expression increased in skeletal muscle cells, accompanied by increased activities of key glycolytic enzymes and decreased activities of enzymes related to mitochondrial oxidative phosphorylation. Galloflavin treatment reduced lactate levels and partially attenuated these metabolic changes. Endogenous co-IP detected lactylation of both PDHA1 and CPT2. Following siRNA-mediated knockdown of AARS2, the protein abundance of PDHA1 and CPT2 increased. Taken together, these findings support an association between hypoxia-induced lactate accumulation, increased AARS2 expression, PDHA1/CPT2 lactylation, and a shift in cellular energy metabolism toward glycolysis. This study provides a theoretical basis for further understanding hypoxia-related metabolic remodeling in yaks.

Premature ovarian failure, resulting from the premature activation of follicles in animals, has been linked to excessive levels of 5α-dihydrotestosterone (DHT). Additionally, melatonin has been demonstrated to be autonomously synthesized and secreted by sheep follicles. However, it remains unclear whether melatonin can counteract excessive DHT in sheep ovaries to support normal follicular development. Here, we investigated the effects of DHT and melatonin on early folliculogenesis in ovine ovaries. Ovarian cortices (~2×2 mm) and secondary follicles (280–360 μm) were cultured for 4 days with high-dose DHT (10⁻⁷ M) and/or melatonin (10⁻⁹ M). H&E staining, TUNEL assay, Western blotting, and RT-qPCR were used to examine the underlying mechanisms. DHT increased the number and diameter of secondary follicles (p < 0.05), but also induced granulosa cell apoptosis, which melatonin alleviated. Mechanistically, DHT upregulated cleaved caspase-3 and caspase-3 expression in granulosa cells, whereas co-treatment with melatonin reduced the Bcl-2/Bax ratio. Using the MT1 inhibitor Luzindole, melatonin was shown to suppress DHT-stimulated granulosa cell proliferation via MT1-mediated Akt phosphorylation, thereby counteracting the DHT-induced decline in follicular reserve. This study elucidates the pathogenic mechanism of DHT-triggered premature ovarian insufficiency and validates the melatonin-mediated protective regulation of follicular development, which provides a theoretical basis for the improvement and protection of reproductive function in reserve breeding ewes.