The FOXO3 gene, a prominent member of the FOXO family, has been identified as a potential quantitative trait locus for muscle atrophy and lipid metabolism in livestock. It is also considered a promising candidate gene for meat quality traits such as Warner–Bratzler shear force (WBSF) and water holding capacity (WHC). The aim of this study was to identify sequence mutations in the FOXO3 gene of yaks and to analyze the association of genotypes and haplotypes with meat traits such as WBSF and WHC. Quantitative reverse-transcriptase PCR (RT-qPCR) was applied to determine the expression levels of FOXO3 in yak tissues, with the results revealing a high expression in the yak longissimus dorsi muscle. Exons of the FOXO3 gene were then sequenced in 572 yaks using hybrid pool sequencing. Five single nucleotide polymorphisms were identified. Additionally, four effective haplotypes and four combined haplotypes were constructed. Two mutations of the FOXO3 gene, namely C>G at exon g.636 and A>G at exon g.1296, were associated with cooked meat percentage (CMP) (p < 0.05) and WBSF (p < 0.05), respectively. Furthermore, the WBSF of the H2H3 haplotype combination was significantly lower than that of other combinations (p < 0.05). The findings of this study suggest that genetic variations in FOXO3 could be a promising biomarker for improving yak meat traits.
Acetyl-CoA carboxylase beta (ACACB) is a functional candidate gene that impacts fat deposition. In the present study, we sequenced exon 37–intron 37, exon 46–intron 46, and intron 47 of yak ACACB using hybrid pool sequencing to search for variants and genotyped the gene in 593 Gannan yaks via Kompetitive allele-specific polymerase chain (KASP) reaction to determine the effect of ACACB variants on carcass and meat quality traits. Seven single nucleotide polymorphisms were detected in three regions. Eight effective haplotypes and ten diplotypes were constructed. Among them, a missense variation g.50421 A > G was identified in exon 37 of ACACB, resulting in an amino acid shift from serine to glycine. Correlation analysis revealed that this variation was associated with the cooking loss rate and yak carcass weight (p = 0.024 and 0.012, respectively). The presence of haplotypes H5 and H6 decreased Warner–Bratzler shear force (p = 0.049 and 0.006, respectively), whereas that of haplotypes H3 and H4 increased cooking loss rate and eye muscle area (p = 0.004 and 0.034, respectively). Moreover, the presence of haplotype H8 decreased the drip loss rate (p = 0.019). The presence of one and two copies of haplotypes H1 and H8 decreased the drip loss rate (p = 0.028 and 0.004, respectively). However, haplotype H1 did not decrease hot carcass weight (p = 0.011), whereas H3 increased the cooking loss rate (p = 0.007). The presence of one and two copies of haplotype H6 decreased Warner–Bratzler shear force (p = 0.014). The findings of the present study suggest that genetic variations in ACACB can be a preferable biomarker for improving yak meat quality.
Abstract Acetyl-CoA carboxylase beta (ACACB) is a rate-limiting enzyme involved in lipid syn-thesis and fatty acid oxidation. The results of our previous study showed that a total of seven SNPs were detected in the exon 37-intron 37, exon 46-intron 46, and intron 47 regions of the yak ACACB, and mutations in the ACACB were found to affect yak meat quality traits. However, the genetic effects of ACACB on yak milk quality traits have not been reported. Therefore, the aim of this study was to investigate the effects of ACACB polymorphisms on yak milk quality traits in Gannan yaks. In this study, A total of 202 Gannan yaks were included in the study. Analyze the different geno-types, diplotypes, and the presence or absence of haplotypes on milk quality. The seven SNPs were named as exon 37-intron 37 (exon 37: SNP1, intron 37: SNP2 and SNP3), exon 46-intron 46 (exon 46: SNP4, intron 46: SNP5), and intron 47 (SNP6 and SNP7). Apart from the SNP1, SNP2, SNP5, and SNP6 loci where the polymorphic information content (PIC) was low (PIC ≤ 0.25), the SNP3, SNP4, and SNP7 loci were all of intermediate polymorphic information status (0.25 < PIC < 0.5). The highest frequency of heterozygosity occurred at the SNP7 locus, and the two alleles were evenly distributed in the population compared to alleles at the other loci. There were no strong linkages between the SNPs (r 2 <0.33) except for a strong linkage disequilibrium observed between SNP1 and SNP2 (r 2 =0.89). Seven effective haplotypes and seven diplotypes were constructed for the Gannan yak ACACB gene. Correlation analysis showed that SNP1 and SNP7 were associated with lactose content ( P <0.05), while SNP3 was significantly associated with the protein and monounsaturated fatty acid contents in the milk ( P <0.05). SNP4 was significantly associated with both saturated and monounsaturated fatty acid contents ( P <0.05 and P <0.01, respectively), while SNPs 5 and 7 were significantly correlated with the fat percentage ( P <0.05) and SNP6 was significantly correlated with total solid content of the milk ( P <0.05). Yaks with the H2H2 diplotype had significantly higher levels of milk fat than other diplotypes ( P <0.05) while milk fat contents in animals carrying hap-lotype H2 were significantly higher than that in yaks carrying the deletion type ( P <0.05). The findings of the present study suggest that polymorphisms in the yak ACACB affect milk quality and can be used as genetic markers for enhancing milk quality in yak populations. The findings provide a theoretical basis for the genetic characterization of milk quality traits in the Gannan yak.
As an indigenous species on the Tibetan Plateau, the yak is well adapted to the plateau hypoxic environment. The high-altitude hypoxia adaptation of the yak requires the adaptive reshaping of multiple tissues and organs, especially the lungs. To reveal the adaptive development of yak lungs under hypoxic stress at the tissue and molecular levels, we conducted histomorphological observations as well as transcriptomic and metabolomic studies of yak lungs at three ages (0.5, 2.5, and 4.5 years). The results showed that the lung tissue developed significantly with age. The mean alveolar area was higher (
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