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Yak has evolved specific adaptative mechanisms to high‐altitude environment. Up to date, only a few studies reported the DNA methylation in yak. In the present study, genome‐wide DNA methylome and transcriptome profiles in lung, mammary, and biceps brachii muscle tissues were compared between yak and three cattle breeds (Tibetan cattle, Sanjiang cattle, and Holstein cattle). The association between differentially expressed genes (DEGs) and differentially methylated regions (DMRs) was analyzed, and the biological functions of DEGs potentially driven by DMRs were explored by KEGG enrichment analysis. Finally, we found that yak‐specific DMRs‐driven DEGs were mainly involved in neuromodulation, respiration, lung development, blood pressure regulation, cardiovascular protection, energy metabolism, DNA repair, and immune functions. The higher levels of the key genes associated with these functions were observed in yak than in cattle, suggesting that DNA methylation might regulate these genes. Overall, the present study contributes basic data at the DNA methylation level to further understand the physiological metabolism in yak. Research Highlights: The difference in methylation level were observed in lung and mammary tissues.Yak‐specific DMRs‐driven DEGs were found.The higher levels of the key genes associated with these above functions were observed in yak than in cattle. [ABSTRACT FROM AUTHOR]

Yaks display unique properties of the lung and heart, enabling their adaptation to high‐altitude environments, but the underlying molecular mechanisms are still largely unknown. In the present study, the proteome differences in lung and heart tissues were compared between yak (Bos grunniens) and three cattle strains (Bos taurus, Holstein, Sanjiang and Tibetan cattle) using the sequential window acquisition of all theoretical mass spectra/data‐independent acquisition (SWATH/DIA) proteomic method. In total, 51,755 peptides and 7215 proteins were identified. In the lung tissue, there were 162, 310 and 118 differential abundance proteins (DAPs) in Tibetan, Holstein and Sanjiang cattle compared to yak respectively. In the heart tissue, there were 71, 57 and 78 DAPs in Tibetan, Holstein and Sanjiang cattle compared to yak respectively. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that the DAPs were enriched for the retinol metabolism and toll‐like receptor categories in lung tissue. The changes in these two pathways may regulate hypoxia‐induced factor and immune function in yaks. Moreover, DAPs in heart tissues were enriched for cardiac muscle contraction, Huntington's disease, chemical carcinogenesis and drug metabolism‐cytochrome P450. Further exploration indicated that yaks may alter cardiac function through regulation of type 2 ryanodine receptor (RyR2) and Ca2+‐release channels. The present results are useful to further develop an understanding of the mechanisms underlying adaptation of animals to high‐altitude conditions. [ABSTRACT FROM AUTHOR]

Yak is an important livestock animal for the people indigenous to the harsh, oxygen‐limited Qinghai‐Tibetan Plateau and Hindu Kush ranges of the Himalayas. The yak genome was sequenced in 2012, but its assembly was fragmented because of the inherent limitations of the Illumina sequencing technology used to analyse it. An accurate and complete reference genome is essential for the study of genetic variations in this species. Long‐read sequences are more complete than their short‐read counterparts and have been successfully applied towards high‐quality genome assembly for various species. In this study, we present a high‐quality chromosome‐scale yak genome assembly (BosGru_PB_v1.0) constructed with long‐read sequencing and chromatin interaction technologies. Compared to an existing yak genome assembly (BosGru_v2.0), BosGru_PB_v1.0 shows substantially improved chromosome sequence continuity, reduced repetitive structure ambiguity, and gene model completeness. To characterize genetic variation in yak, we generated de novo genome assemblies based on Illumina short reads for seven recognized domestic yak breeds in Tibet and Sichuan and one wild yak from Hoh Xil. We compared these eight assemblies to the BosGru_PB_v1.0 genome, obtained a comprehensive map of yak genetic diversity at the whole‐genome level, and identified several protein‐coding genes absent from the BosGru_PB_v1.0 assembly. Despite the genetic bottleneck experienced by wild yak, their diversity was nonetheless higher than that of domestic yak. Here, we identified breed‐specific sequences and genes by whole‐genome alignment, which may facilitate yak breed identification. [ABSTRACT FROM AUTHOR]

To assess the genetic diversity and relationship of the Tibetan yak breeds. The genetic diversity and phylogenies of a total of 480 individual from 11 Tibetan yak groups were analyzed using PCR and multiplex gel electrophoresis of silver staining technology with eight pairs of microsatellite markers.The result showed that these markers were highly polymorphic loci with rich genetic diversity in the Tibetan yak populations.The average polymorphic information content (PIC) in 11 groups of yak were higher than 0.5. The highest HEL13 was 0.8496, and the lowest TGLA57 was 0.7349. Among them, the PICof Dingqing yak was minimum (0.7505), indicating that the group is relatively pure.Sangri Yak had the highest PIC value (0.7949) indicating greater genetic variationwithinthe groups. Among the 11 groups examined, the order of heterozygosity size wasSangri(0.8193)>Jiangda(0.8190)>Sangsang(0.8157)>Baqing(0.8150)>Kangbu(0.8123)> Jiali(0.8087)>Gongbujiangda(0.8054)>Sibu(0.8041)>Leiwuqi(0.8033)>Pali(0.8031)>Dingqing(0.7831). The groups from eastern Tibet had grater genetic diversity than those from Western Tibet, which indicate that Tibet may be one of the cradles of the yak.According to the genetic distance, the cluster relationship constructed with UPGMA and NJ methods showed that 11 yak groups in Tibet could be divided into three forms. In summary,Tibet yak has abundant genetic diversity and the selected microsatellite markers can be used to evaluategenetic diversity of Tibetan yak.