Search

Simple Summary: This study utilized small RNA sequencing to explore how the expression of miRNAs differs in milk-derived exosomes from yaks living at different altitudes. The analysis revealed distinct miRNAs associated with yak adaptations to environmental pressures such as mastitis, viral infections, and heat stress. These findings suggest that miRNAs carried by yak milk-derived exosomes play a crucial role in yak resilience, disease resistance, and immune regulation, offering valuable insights for a deeper understanding of yak adaptation. Yaks are a rare and unique animal species inhabiting the Qinghai–Tibet Plateau; they are renowned for their remarkable ability to thrive in harsh environments. Milk-derived exosomes, tiny vesicles containing various biological molecules, play crucial roles in numerous pathological and physiological processes, including cell growth, development, and immune regulation. This study delved into the microRNA expression profiles of yak milk-derived exosomes collected from both high- and low-altitude populations using small RNA sequencing. These miRNAs were found to be implicated in pathways associated with mammary gland inflammation, virus infection regulation, and heat stress response. Functional enrichment analyses, utilizing GO and KEGG databases, revealed that the target genes of these differentially expressed miRNAs are enriched in signaling pathways crucial for Th17 cell differentiation and the Ras-MAPK signaling pathway. In conclusion, this research illuminates the adaptive mechanisms of yaks through the differential expression of miRNAs in their milk-derived exosomes across varying environmental conditions. These findings provide a valuable foundation for future investigations into yak resilience and the potential of milk-derived exosomes as tools for disease management and immune modulation. [ABSTRACT FROM AUTHOR]

Yak (Bos grunniens) is a large ruminant endemic to the Tibetan plateau. The addition of enzyme complexes to feed can significantly improve their growth performance. Therefore, studying the effects of ruminant compound enzyme preparations dosage on yak rumen microorganisms and production performance is crucial to promoting the development of the yak industry. This study aimed to determine the effects of feeding yaks with different doses of ruminant enzyme compounds on the performance, meat quality, and rumen microorganisms of yaks. Three kinds of experimental diets with doses of 0.5 g/kg (LE group), 1 g/kg (ME group), and 2 g/kg (HE group) were selected to determine the growth index, meat quality, serum biochemical indexes, rumen fluid pH and other indexes of the three experimental groups. Metagenomics studies were used to investigate the differences in rumen microbial composition and function among yak groups, and transcriptome sequencing of the longest dorsal muscle was performed to reveal the expression of differential genes among different groups. It was determined that the levels of dietary enzyme complexes significantly affected growth performance, rumen fluid pH, and serum biochemical indices. At the phylum level, the dominant phylum in all three treatment groups was Bacteroidota, Bacillota, Kiritimatiellota, and Pseudomonadota. At the genus level, Prevotella, Methanobrevibacter, Oscillibacter. Fibrobacter showed statistically significant differences in abundance (p < 0.05). CAZymes family analysis revealed significant differences in GHs, CTs, and CEs among the three groups. Genome-wide differential gene expression in the longest muscle of the yak back was analyzed by RNA-seq between the three experimental groups. Some DEGs were found to be enriched in the ECM, PI3K-Akt, PPAR, and protein digestion and absorption receptor pathways. Combined metagenomics and transcriptomics analyses revealed that some microorganisms were significantly associated with the genes COL11A1, POSTN, and PTHLH, which are involved in growth metabolism. In summary, this study investigated the effects and interrelationships of ruminant complex enzymes on yak performance, meat quality, and rumen environment. The results of this study provide a scientific basis for adding ruminant enzymes to yaks. [ABSTRACT FROM AUTHOR]

Single-cell sequencing technology provides apparent advantages in cell population heterogeneity, allowing individuals to better comprehend tissues and organs. Sequencing technology is currently moving beyond the standard transcriptome to the single-cell level, which is likely to bring new insights into the function of breast cells. In this study, we examine the primary cell types involved in breast development, as well as achievements in the study of scRNA-seq in the microenvironment, stressing the finding of novel cell subsets using single-cell approaches and analyzing the problems and solutions to scRNA-seq. Furthermore, we are excited about the field's promising future. [ABSTRACT FROM AUTHOR]

Yaks are crucial to local herders' economy and agriculture. However, several diseases pose a significant threat to the health of yaks and cause substantial economic losses for herders. Therefore, studying the immune indicators and breeding of yaks has become an important task. This study aimed to investigate the association between single nucleotide polymorphisms (SNPs) of the G protein-activated inwardly rectifying K+ channel 2 (KCNJ6, GIRK2) gene and yak immune indicators, with the goal of identifying potential candidate molecular markers for yak breeding. In this study, we genotyped 192 healthy adult yaks and detected three SNPs (g163684421 C > T, g163688148 C > T, and g163690745 T > C) in the yak KCNJ6 gene. These SNPs were found to be distributed in the yak population. Subsequently, we performed a linkage disequilibrium analysis and found that the linkage disequilibrium levels of g163684421 C > T and g163690745 T > C were relatively high. Through a correlation analysis of yak KCNJ6 gene SNPs and immune indicators, we found that g163684421 C > T and g163690745 T > C were significantly associated with IgA, IgG, IgM, CRP, HP, IL-2, IL-4, IFN-γ, and TNF-α (p < 0.05), and the mutation of these SNPs leads to a decrease in yak immune indicators. On the other hand, g163688148 C > T was significantly associated with IgG, IL-4, IFN-γ, TNF-α, IgA, CRP, and HP (p < 0.05), and the mutation of this SNP leads to an increase in yak immune indicators. In conclusion, we identified SNPs associated with yak immune indicators and found that KCNJ6 gene polymorphisms can serve as candidate molecular markers for yak immune indicators. This study provides valuable genetic resources for marker-assisted selection in yak breeding. The results of this study are of great importance for the research on yak immune indicators and marker-assisted selection in yak breeding. [ABSTRACT FROM AUTHOR]

Simple Summary: Yaks are indispensable economic animals in pastoral areas, providing local herdsmen with abundant necessities of life. Their meat is of excellent quality and highly favored by the market. As a newly cultivated breed, the Ashidan yak has been under continuous selection and breeding to improve its production performance, which is a long-term goal. The growth traits of yaks are crucial indicators of their economic benefits. Therefore, through the use of SNP molecular marker-assisted selection technology, the early and precise selection of yak growth traits can be achieved. This technology effectively accelerates the pace of genetic improvement and enhances breeding efficiency. The tyrosine protein kinase (TXK) gene, as a member of the non-receptor tyrosine kinase Tec family, plays a vital role in signal transduction mediation. Phospholipase C epsilon 1 (PLCE1), a membrane-associated enzyme, is of paramount importance for the differentiation of myoblasts and the normal functioning of muscle tissue. In recent years, both of these genes have been reported to be associated with the economic traits of animals. This study aimed to investigate the relationship between single nucleotide polymorphisms (SNPs) in the TXK and PLCE1 genes and growth traits in Ashidan yaks and to search for potential molecular marker loci that can influence Ashidan yak breeding. A cGPS liquid microarray was utilized to genotype 232 Ashidan yaks and to analyze correlations between two SNP loci in the TXK and PLCE1 genes and yak body weight, body height, body length, and chest circumference at different periods. The results indicated that the g.55,999,531C>T locus of the TXK gene and the g.342,350T>G locus of the PLCE1 gene were significantly correlated with the growth traits of Ashidan yaks. Among these, individuals with the CC genotype at the g.55,999,531C>T locus showed a significantly higher body length at 6 months old compared to TT individuals, and those with the CT genotype at 12 months old had a significantly higher chest circumference than TT individuals. At the g.342,350T>G locus, the body height of GG genotype individuals at 18 months of age was significantly higher than that of TT genotype individuals and TG genotype individuals. The above findings can be used as theoretical support for the subsequent improvement of Ashidan yak breeding. [ABSTRACT FROM AUTHOR]

The IQ motif containing GTPase activating protein 2 (IQGAP2) gene functions as a tumor suppressor, reducing the malignant properties of breast cancer cells. The circulating cartilage acidic protein 1 (CRTAC1) gene, present in the whey protein fraction of dairy cows throughout lactation, is significantly correlated with fatty acids in milk. In this study, we investigated the correlation between single nucleotide polymorphisms (SNPs) in the IQGAP2 and CRTAC1 genes and milk quality traits in Gannan yaks, aiming to identify potential molecular marker loci for enhancing milk quality. Using the Illumina Yak cGPS 7K liquid chip, we genotyped 162 yaks and identified five SNPs in the IQGAP2 (g.232,769C>G, g.232,922G>C) and CRTAC1 (g.4,203T>C, g.5,348T>G, g.122,451T>C) genes. Genetic polymorphism analysis revealed that these five SNPs were moderately polymorphic and in Hardy–Weinberg equilibrium. An association analysis results showed that, at the g.232,769C>G locus of the IQGAP2 gene, the heterozygous CG genotype had significantly higher lactose content than the CC and GG homozygous genotypes (p < 0.05). Similarly, at the g.232,922G>C locus, the heterozygous GC and mutant CC genotypes significantly increased the contents of milk fat, lactose, and total solids (TS) (p < 0.05). In the CRTAC1 gene (g.4,203T>C, g.5,348T>G, g.122,451T>C), the mutant CC genotype significantly increased milk fat content, while the heterozygous TG genotype significantly increased lactose content (p < 0.05). In summary, mutations at the loci of g.232,769C>G, g.232,922G>C, g.4,203T>C, g.5,348T>G, and g.122,451T>C significantly elevated the lactose, milk fat, and TS content in Gannan yak milk, providing potential molecular marker candidates for improving Gannan yak milk quality. [ABSTRACT FROM AUTHOR]

Lysozyme like 4 (LYZL4), lysozyme like 6 (LYZL6) and proliferating cell nuclear antigen (PCNA) are implicated in the regulation of testicular function, but there was no research reported available on the expression patterns of LYZL4, LYZL6 and PCNA genes at different developmental stages of yak testes. In this study, we used the qRT-PCR, western blotting and immunohistochemistry estimated the LYZL4, LYZL6 and PCNA gene expression and protein lo-calization at different developmental stages of yak testes. The qPCR results showed that the mRNA expression of LYZL4, LYZL6 and PCNA genes significantly increased with age in the testes of yaks. Western blot results showed that the protein abundance of LYZL4, LYZL6 and PCNA in yak testes was significantly higher after puberty than before puberty. Furthermore, the results of immunohistochemistry indicated that LYZL4, LYZL6 and PCNA may be involved in the regulation of spermatogonia proliferation and Leydig cell function in immature testis. In adult yak testes, LYZL4, LYZL6 and PCNA may involve in the development of round spermatids and primary spermatocytes during testicular development. Our results indicated that LYZL4, LYZL6 and PCNA may be involved in the development of Sertoli cells, Leydig cells and gonocytes in yak testes. [ABSTRACT FROM AUTHOR]

The Meiren yak is an important genetic resource in Gansu Province, China. In this study, we aimed to explore the evolutionary history and population structure of the genetic resource of Meiren yak and to mine the characteristic genes of Meiren yak. We analysed a total of 93 yaks of eight yak breeds based on whole genome resequencing combined with population genomics and used θπ ratio and Fst method to screen the selected sites in the genome region. The results proved that Meiren yak can be used as a potential genetic resource in Gansu Province. The genes in Meiren yak with positive selection in selection signal analysis were subjected to the Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analyses, which indicated that the genes were related to the adaptability to high altitude and hypoxic environment. By analysing the genetic variation of Meiren yak at the genome-wide level, this study provided a theoretical basis for genetic improvement of Meiren yak and for the development of high-quality yak resources. [ABSTRACT FROM AUTHOR]

Yak is an important dominant livestock species at high altitude, and the growth performance of yak has obvious differences under different feeding methods. This experiment was conducted to compare the effects of different feeding practices on growth performance and meat quality of yaks through combined transcriptomic and metabolomic analyses. In terms of yak growth performance, compared with traditional grazing, in-house feeding can significantly improve the average daily weight gain, carcass weight and net meat weight of yaks; in terms of yak meat quality, in-house feeding can effectively improve the quality of yak meat. A combined transcriptomic and metabolomic analysis revealed 31 co-enriched pathways, among which arginine metabolism, proline metabolism and glycerophospholipid metabolism may be involved in the development of the longissimus dorsi muscle of yak and the regulation of meat quality-related traits. The experimental results increased our understanding of yak meat quality and provided data materials for subsequent deep excavation of the mechanism of yak meat quality. [ABSTRACT FROM AUTHOR]

This study explored the polymorphism of the leucine aminopeptidase (LAP3) gene and its relationship with milk quality characteristics in Gannan yak. A cohort of 162 Gannan yak was genotyped utilizing the Illumina Yak cGPS 7K BeadChip, and the identified single nucleotide polymorphisms (SNPs) were evaluated for their association with milk protein, casein, lactose, and fat concentrations. The results showed that four SNPs (g.4494G > A, g.5919A > G, g.8033G > C, and g.15,615A > G) in the LAP3 gene exhibited polymorphism with information content values of 0.267, 0.267, 0.293, and 0.114, respectively. All four SNPs were in Hardy–Weinberg equilibrium (p > 0.05). The g.4494G > A and g.5919A > G SNPs were significantly associated with protein content (p < 0.05), with homozygous genotypes showing significantly higher protein content than heterozygous genotypes (p < 0.05). The g.8033G > C SNP was significantly associated with casein content, protein content, non-fat solids, and acidity (p < 0.05), with the CC genotype having significantly higher casein, protein, and non-fat solids content than the GG and GC genotypes (p < 0.05). The g.15,615A > G SNP was significantly associated with average fat globule diameter (p < 0.05). In general, the mutations within the LAP3 gene demonstrated a positive impact on milk quality traits in Gannan yak, with mutated genotypes correlating with enhanced milk quality. These results indicate that the LAP3 gene could be a significant or candidate gene affecting milk quality traits in Gannan yak and offer potential genetic markers for molecular breeding programs in this species. [ABSTRACT FROM AUTHOR]

Energy feed can provide animals with balanced nutrition, thereby enhancing their growth performance. This study aimed to evaluate the effects of dietary energy levels on the growth performance, serum metabolites, and meat quality of Jersey cattle–yaks. A total of 24 male Jersey cattle–yaks were randomly divided into three groups. Each group was fed diets with metabolizable energy levels of 8.21 MJ/kg (LE), 9.50 MJ/kg (ME), and 10.65 MJ/kg (HE), respectively. The HE and ME groups showed significantly higher final body weight, average daily gain (ADG), and feed efficiency compared to the LE group (p < 0.05). The glucose (GLU) and total cholesterol (TC) concentrations were significantly increased in the serum of the ME and HE groups (p < 0.05). The low-density lipoprotein cholesterol (LDL-C) and alanine aminotransferase (ALT) levels were significantly higher in the serum of the HE group than in the ME group (p < 0.05). Blood urea nitrogen (BUN) levels exhibited a significant decrease with increasing metabolizable energy levels in the diet (p < 0.05). Increasing dietary energy levels enhances the eye muscle area and intramuscular fat content of Jersey cattle–yaks (p < 0.05), with no effect on pH45 min, pH24 h, and shear force. In the HE group, the levels of heneicosanoic acid (C21:0), palmitoleic acid (C16:1), elaidic acid (C18:1n9t), and eicosadienoic acid (C20:2n6) were notably elevated (p < 0.05) when compared to the LE group. We concluded that a higher dietary energy level enhanced the growth performance and meat quality traits of male Jersey cattle–yaks. [ABSTRACT FROM AUTHOR]

Male reproductive health is largely determined already in the early development of the testis. Although much work has been carried out to study the mechanisms of testicular development and spermatogenesis, there was previously no information on the differences in the protein composition of yak testicles during early development. In this study, the protein profiles in the testicles of 6- (M6), 18- (M18), and 30-month-old (M30) yaks were comparatively analyzed using TMT proteomics. A total of 5521 proteins were identified, with 13, 1295, and 1397 differentially expressed proteins (DEPs) in 30- vs. 18-, 18- vs. 6-, and 30- vs. 6-month-old testes, respectively. Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that DEPs were mainly involved in signaling pathways related to testicular development and spermatogenesis, including the MAPK, PI3K–Akt, Wnt, mTOR, TGF-β, and AMPK signaling pathways. Furthermore, we also identified eight potential proteins (TEX101, PDCL2, SYCP2, SYCP3, COL1A1, COL1A2, ADAM10, and ATF1) that may be related to the testicular development and spermatogenesis of yaks. This study may provide new insights into the molecular mechanisms of the testicular development and spermatogenesis of yaks. [ABSTRACT FROM AUTHOR]

Yak milk, known as the "liquid gold", is a nutritious food with extensive consumption. Compared with cow milk, yak milk contains higher levels of nutrients such as dry matter, milk fat, and milk protein, which demonstrates great potential for exploitation and utilization. Protein kinase cGMP-dependent 1 (PRKG1) is an important functional molecule in the cGMP signaling pathway, and its significant influence on milk fatty acids has been discovered. The aim of this study is to explore the correlation between single nucleotide polymorphisms (SNPs) in the PRKG1 gene and the quality traits of Gannan yak milk in order to identify candidate molecular markers for Gannan yak breeding. In this study, genotyping was performed on 172 healthy, 4–5-year-old lactating Gannan yaks with similar body types, naturally grazed, and two to three parity. Three SNPs (g.404195C>T, g.404213C>T, and g.760138T>C) were detected in the PRKG1 gene of Gannan yaks, which were uniformly distributed in the yak population. Linkage disequilibrium analysis was conducted, revealing complete linkage disequilibrium between g.404195C>T and g.404213C>T. After conducting a correlation analysis between SNPs in the PRKG1 gene and milk quality in Gannan yaks, we found that PRKG1 SNPs significantly increased the content of casein, protein, and SNFs in yak milk. Among them, the TT homozygous genotype at the PRKG1 g.404195C>T loci exhibited higher casein and protein contents compared to the CC and CT genotypes (p < 0.05). The SNP g.760138T>C locus was associated with casein, protein, SNFs, and TS traits (p < 0.05). The CC genotype had higher casein and protein contents than the TT and TA genotypes (p < 0.05). However, there were no significant differences in milk fat, lactose, and acidity among the three genotypes (p > 0.05). In summary, PRKG1 gene polymorphism can serve as a candidate molecular marker for improving milk quality in Gannan yaks. [ABSTRACT FROM AUTHOR]

In this study, our primary aim was to explore the genomic landscape of Barka cattle, a breed recognized for high milk production in a semi-arid environment, by focusing on genes with known roles in milk production traits. We employed genome-wide analysis and three selective sweep detection methods (ZFST, θπ ratio, and ZHp) to identify candidate genes associated with milk production and composition traits. Notably, ACAA1, P4HTM, and SLC4A4 were consistently identified by all methods. Functional annotation highlighted their roles in crucial biological processes such as fatty acid metabolism, mammary gland development, and milk protein synthesis. These findings contribute to understanding the genetic basis of milk production in Barka cattle, presenting opportunities for enhancing dairy cattle production in tropical climates. Further validation through genome-wide association studies and transcriptomic analyses is essential to fully exploit these candidate genes for selective breeding and genetic improvement in tropical dairy cattle. [ABSTRACT FROM AUTHOR]

Simple Summary: Yaks are a major economic source for people in the Tibetan Plateau region. Yaks are rich in nutrients, but their low fat content is not conducive to the large-scale promotion of yak meat, so the study of the mechanism of yak lipid deposition is beneficial to the marketing of yak meat. In this paper, the results of transcriptome sequencing analysis of yak liver showed that it could be determined that the expression levels of genes associated with partial lipid deposition were significantly up-regulated during yak fattening. In addition, this study found that the tenderness of yak meat improved during this process. Fattening significantly affects fat deposition in yaks, which may be realized through its effects on lipid metabolic pathways. Therefore, studying the mechanism of lipid deposition in yaks and fattening yaks will improve the quality of yak meat. Yak meat is nutritionally superior to beef cattle but has a low fat content and is slow-growing. The liver plays a crucial role in lipid metabolism, and in order to determine whether different feeding modes affect lipid metabolism in yaks and how it is regulated, we employed RNA sequencing (RNA-seq) technology to analyze the genome-wide differential gene expression in the liver of yaks maintained under different raising systems. A total of 1663 differentially expressed genes (DEGs) were identified (|log2FC| ≥ 0 and p-value ≤ 0.05), including 698 down-regulated and 965 up-regulated genes. According to gene ontology (GO) and KEGG enrichment analyses, these DEGs were significantly enriched in 13 GO terms and 26 pathways (p < 0.05). Some DEGs were enriched in fatty acid degradation, PPAR, PI3K-Akt, and ECM receptor pathways, which are associated with lipid metabolism. A total of 16 genes are well known to be related to lipid metabolism (e.g., APOA1, FABP1, EHHADH, FADS2, SLC27A5, ACADM, CPT1B, ACOX2, HMGCS2, PLIN5, ACAA1, IGF1, FGFR4, ALDH9A1, ECHS1, LAMA2). A total of 11 of the above genes were significantly enriched in the PPAR signaling pathway. The reliability of the transcriptomic data was verified using qRT-PCR. Our findings provide new insights into the mechanisms regulating yak meat quality. It shows that fattening improves the expression of genes that regulate lipid deposition in yaks and enhances meat quality. This finding will contribute to a better understanding of the various factors that determine yak meat quality and help develop strategies to improve yield and quality. [ABSTRACT FROM AUTHOR]