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Simple Summary: Yaks are among the largest high-altitude mammals in the world, and they are ideally adapted to the harsh environmental conditions of the plateau regions. Yaks are thus central to the lives of herdsmen and other local populations in these high-altitude areas. Copy number variations (CNVs) are an important cause of genomic variation in livestock and identifying advantageous CNVs can aid in livestock breeding efforts. In this study, an association between CNVs in the MICALL2 and MOGAT2 genes and Ashidan yak growth traits was confirmed, providing a theoretical foundation for Ashidan yak breeding and meat production efforts. Copy number variations (CNVs) are a result of genomic rearrangement affecting DNA regions over 1 kb in length, and can include inversions, translocations, deletions, and duplications. The molecule interacting with CasL-like protein 2 (MICALL2) gene is primarily associated with mitochondrial protein targeting and exhibits predicted stress fiber colocalization. The monoacylglycerol O-acyltransferase 2 (MOGAT2) gene encodes an enzyme responsible for catalyzing diacylglycerol synthesis from 2-monoacylglycerol and fatty acyl-CoA. For this study, blood samples were obtained from 315 yaks, and the body weight, body length, withers height, and chest girth of these animals were measured at 6, 12, 18, and 30 months of age. Genomic DNA was harvested from the collected blood samples, and CNVs in these samples were detected by qPCR. The resultant data were compared using ANOVAs, revealing significant associations between MICALL2 gene CNVs and body weight at 6 months of age (p < 0.05), body length and chest girth at 30 months of age (p < 0.05), and withers height at 18 months of age (p < 0.01) in Ashidan yaks. Similarly, MOGAT2 CNVs were significantly associated with body weight at 6 and 30 months of age (p < 0.05), and with withers height at 18 months of age (p < 0.01) in these Ashidan yaks. MICALL2 and MOGAT2 gene expression was further analyzed in yak tissue samples, revealing that MICALL2 was most highly expressed in the adipose tissue, whereas MOGAT2 was most highly expressed in the lung. These results thus confirmed the relationship between CNVs in the MICALL2 and MOGAT2 genes and Ashidan yak growth traits, providing a valuable gene locus that can be leveraged for future marker-assisted yak breeding efforts. [ABSTRACT FROM AUTHOR]

Testis-specific genes play an essential part in the centromere union during meiosis in male germ cells, spermatogenesis, and in fertility. Previously, there was no research report available on the expression pattern of SYCP3 and TSEG2 genes in different ages of yaks. Therefore, the current research compared the expression profiling of SYCP3 and TSEG2 genes in testes of yaks. The expression pattern of SYCP3 and TSEG2 mRNA was investigated using qPCR, semi-quantitative PCR, western blot, immunohistochemistry, and molecular bioinformatics. Our findings displayed that SYCP3 and TSEG2 genes were prominently expressed in the testicles of yaks as compared to other organs. On the other hand, the protein encoded by yak SYCP3 contains Cor1/Xlr/Xmr conserved regions, while the protein encoded by yak TSEG2 contains synaptonemal complex central element protein 3. Additionally, multiple alignments sequences indicated that proteins encoded by Datong yak SYCP3 and TSEG2 were highly conserved among mammals. Moreover, western blot analysis specified that the molecular mass of SYCP3 protein was 34-kDa and TSEG2 protein 90-kDa in the yak. Furthermore, the results of immunohistochemistry also revealed the prominent expression of these proteins in the testis of mature yaks, which indicated that SYCP3 and TSEG2 might be essential for spermatogenesis, induction of central element assembly, and homologous recombination. [ABSTRACT FROM AUTHOR]

• The CNV of the HSF1 gene was detected in Ashidan yaks. • There were significant correlations between HSF1-CNV and growth traits of yaks. • The expression level of the HSF1 gene was variable in different tissues of yaks. Copy Number Variation (CNV) is the major manner for the variation of genome structure, which is associated with numerous important traits. The heat shock factor 1 (HSF1) gene is a stress response transcriptional regulator. It participates in the heat shock response, simultaneously participated in the development of tissue. The objective of this research was to explore the influence of CNV of the HSF1 gene on the growth traits of the Ashidan yak. In this study, the growth traits (withers height, body weight, chest girth, and body length) of 274 Ashidan yaks were divided into four stages (6, 12, 18, and 30 months old). Moreover, quantitative polymerase chain reaction (qPCR) was exploited for determining the HSF1 gene relative expression level, and SPSS software was utilized for the statistical analysis. The outcomes indicated that HSF1 -CNV was significantly associated with body length (p < 0.05) and was extremely significant associated with withers height (p < 0.01) of 18-month-old Ashidan yaks. Besides, the HSF1 relative expression in heart and muscle was higher than that existed in other tissues (p < 0.01). The outcomes suggested that the CNV of HSF1 gene would affect the growth and development of the Ashidan yak, which is conducive to the early breeding of yak. [ABSTRACT FROM AUTHOR]

• The CNV of the HPGDS gene was detected in yak. • The expression level of the HPGDS gene was variable in different tissues of yaks. • The HPGDS gene was highly expressed in the spleen and lung of all ages. • There were significant correlations between HPGDS -CNV and growth traits of yaks. Copy number variation (CNV) is a structural variation at the submicroscopic level of the genome, which can affect gene-related phenotypes by changing genes dosage and transcript structure. Hematopoietic prostaglandin D synthase (HPGDS) is a member whose functions are closely related to weight gain and inflammatory diseases of the glutathione S-transferase (GSTs) family. In this study, the growth characteristics (body weight, withers height, body length, and chest girth) of 336 Ashidan yaks were monitored at four stages (6 months, 12 months, 18 months, and 30 months). In addition, CNV of the HPGDS gene was detected, discovered relationships of CNV with growth traits, and explored the level of gene expression. Based on the statistical analysis by IBM SPSS software, significant correlations were observed between HPGDS -CNV and body weight in 12-month-old yak (P < 0.01), 18-month-old yak (P < 0.001) and 30-month-old yak (P < 0.001) and body length in 18-month-old yak (P < 0.05) and 30-month-old yak (P < 0.05), respectively. Additionally, the individuals with gain copy number type performed better in body weight and body length than those with normal or loss copy number type. To our best of knowledge, this is the first time to make efforts to probe into the role of HPGDS -CNV and its interaction with livestock growth traits. Our results suggested that the CNV of the HPGDS gene may be an active candidate gene for the marker-assisted selection (MAS) of yaks. [ABSTRACT FROM AUTHOR]