The Yushu yak is one of China’s distinctive yak breeds, primarily distributed in the Yushu Tibetan Autonomous Prefecture of Qinghai Province and its surrounding areas. Yushu yaks are not only economically and culturally significant but also play a crucial role in protecting the ecosystem of the Qinghai-Tibet Plateau and promoting sustainable development. However, there are no clear records regarding the ancestry, population structure, and unique traits of Yushu yaks. Therefore, this study conducted an analysis of genetic diversity, population structure, and selection signals in Yushu yak populations, aiming to provide references for the conservation and utilization of the breed genetic resources. The results of the analysis showed that the Yushu yak population has high genetic diversity and low inbreeding coefficients, indicating a stable genetic structure. Population structure analysis revealed that the Yushu yak lineage is unique, with limited gene flow between domestic and wild yaks. Functional enrichment analysis of positively selected genes in Yushu yaks indicated prominent selection features related to growth and development as well as energy metabolism. Additionally, we classified the Yushu yak breeding bulls into family lineages based on kinship, which is essential for improving the efficiency of utilizing genetic resources and scientifically managing the population.

Lactation is a complex physiological process regulated by numerous genes and factors. Circular RNA (circRNA), a non-coding RNA, acts as a molecular sponge that sequesters microRNAs (miRNAs) to regulate target gene expression. Although circRNA has been linked to mammary gland lactation, its specific role in yaks remains underexplored. This study employed circular RNA sequencing (circRNA-seq) to examine the differential expression of circRNAs in yak mammary tissues during lactation and the dry period. Additionally, an enrichment analysis of the differentially expressed circRNAs (DECs) was performed. A competing endogenous RNA (ceRNA) network was then constructed to explore the potential of their roles in lactation and mammary gland development. We detected 18,905 circRNAs in yak mammary tissue, among which 302 showed differential expression. The host genes of these DECs were enriched in functions and pathways associated with yak milk synthesis and composition. Through the construction of a ceRNA network and the enrichment analysis of associated mRNAs, this study identified ceRNAs potentially involved in regulating lactation and mammary gland development. In conclusion, circRNAs in yak mammary tissues were identified and analyzed across lactation and dry periods, establishing a ceRNA network related to lactation regulation. These findings provide novel insights into the regulatory mechanisms governing lactation in yaks (Bos grunniens).

Fast-twitch and slow-twitch muscle fibers not only differ in metabolic characteristics and physiological functions but also significantly influence the texture of livestock meat. RNA editing represents an important post-transcriptional regulatory process that can influence both gene expression and the resulting protein function. However, studies on RNA editing events in yak muscle remain limited. This study systematically identified RNA editing events in yak biceps femoris (BF, n = 3) and obliquus externus abdominis (OEA, n = 3) using transcriptomic data, discovering 17,713 unique editing sites, most located in non-coding regions. Within coding regions, 3350 sites were detected, with 1195 resulting in non-synonymous amino acid substitutions. Further analysis revealed that 785 sites potentially affected miRNA binding sites, suggesting RNA editing may participate in miRNA-mediated gene regulation. Tukey’s post hoc test (p < 0.05) identified 242 sites (involving 170 genes) with significantly different editing levels between BF and OEA. KEGG pathway analysis indicated that genes with differential RNA editing were predominantly associated with pathways involved in muscle fiber type transitions, including the MAPK and calcium signaling pathways. Collectively, this study maps the RNA editing landscape in yak muscle tissue and identifies distinct, fiber-type-specific RNA editing patterns between oxidative and glycolytic muscle fibers, including differences in editing levels and site distributions, supporting a potential association between RNA editing and muscle fiber type transformation.