Effect of two non-synonymous ecto-5'-nucleotidase variants on the genetic architecture of inosine 5'-monophosphate (IMP) and its degradation products in Japanese Black beef.

BACKGROUND: Umami is a Japanese term for the fifth basic taste and is an important sensory property of beef palatability. Inosine 5'-monophosphate (IMP) contributes to umami taste in beef. Thus, the overall change in concentration of IMP and its degradation products can potentially affect the beef palatability. In this study, we investigated the genetic architecture of IMP and its degradation products in Japanese Black beef. First, we performed genome-wide association study (GWAS), candidate gene analysis, and functional analysis to detect the causal variants that affect IMP, inosine, and hypoxanthine. Second, we evaluated the allele frequencies in the different breeds, the contribution of genetic variance, and the effect on other economical traits using the detected variants. RESULTS: A total of 574 Japanese Black cattle were genotyped using the Illumina BovineSNP50 BeadChip and were then used for GWAS. The results of GWAS showed that the genome-wide significant single nucleotide polymorphisms (SNPs) on BTA9 were detected for IMP, inosine, and hypoxanthine. The ecto-5'-nucleotidase (NT5E) gene, which encodes the enzyme NT5E for the extracellular degradation of IMP to inosine, was located near the significant region on BTA9. The results of candidate gene analysis and functional analysis showed that two non-synonymous SNPs (c.1318C > T and c.1475 T > A) in NT5E affected the amount of IMP and its degradation products in beef by regulating the enzymatic activity of NT5E. The Q haplotype showed a positive effect on IMP and a negative effect on the enzymatic activity of NT5E in IMP degradation. The two SNPs were under perfect linkage disequilibrium in five different breeds, and different haplotype frequencies were seen among breeds. The two SNPs contribute to about half of the total genetic variance in IMP, and the results of genetic relationship between IMP and its degradation products showed that NT5E affected the overall concentration balance of IMP and its degradation products. In addition, the SNPs in NT5E did not have an unfavorable effect on the other economical traits. CONCLUSION: Based on all the above findings taken together, two non-synonymous SNPs in NT5E would be useful for improving IMP and its degradation products by marker-assisted selection in Japanese Black cattle.

SNP- and haplotype-based genome-wide association studies for growth, carcass, and meat quality traits in a Duroc multigenerational population.

BACKGROUND: The aim of the present study was to compare the power of single nucleotide polymorphism (SNP)-based genome-wide association study (GWAS) and haplotype-based GWAS for quantitative trait loci (QTL) detection, and to detect novel candidate genes affecting economically important traits in a purebred Duroc population comprising seven-generation pedigree. First, we performed a simulation analysis using real genotype data of this population to compare the power (based on the null hypothesis) of the two methods. We then performed GWAS using both methods and real phenotype data comprising 52 traits, which included growth, carcass, and meat quality traits. RESULTS: In total, 836 animals were genotyped using the Illumina PorcineSNP60 BeadChip and 14 customized SNPs from regions of known candidate genes related to the traits of interest. The power of SNP-based GWAS was greater than that of haplotype-based GWAS in a simulation analysis. In real data analysis, a larger number of significant regions was obtained by SNP-based GWAS than by haplotype-based GWAS. For SNP-based GWAS, 23 genome-wide significant SNP regions were detected for 17 traits, and 120 genome-wide suggestive SNP regions were detected for 27 traits. For haplotype-based GWAS, 6 genome-wide significant SNP regions were detected for four traits, and 11 genome-wide suggestive SNP regions were detected for eight traits. All genome-wide significant SNP regions detected by haplotype-based GWAS were located in regions also detected by SNP-based GWAS. Four regions detected by SNP-based GWAS were significantly associated with multiple traits: on Sus scrofa chromosome (SSC) 1 at 304 Mb; and on SSC7 at 35-39 Mb, 41-42 Mb, and 103 Mb. The vertnin gene (VRTN) in particular, was located on SSC7 at 103 Mb and was significantly associated with vertebrae number and carcass lengths. Mapped QTL regions contain some candidate genes involved in skeletal formation (FUBP3; far upstream element binding protein 3) and fat deposition (METTL3; methyltransferase like 3). CONCLUSION: Our results show that a multigenerational pig population is useful for detecting QTL, which are typically segregated in a purebred population. In addition, a novel significant region could be detected by SNP-based GWAS as opposed to haplotype-based GWAS.

Genome-wide association studies identified variants for taurine concentration in Japanese Black beef.

We performed genome-wide association studies (GWAS) using the BovineSNP50 array to detect significant single nucleotide polymorphisms (SNPs) that may affect the concentration of 22 free amino acids and three peptides in Japanese Black beef cattle. A total of 574 Japanese Black cattle and 40,657 SNPs from the array were used for this study. Genome-wide significant SNPs were detected for ß-alanine (three SNPs on chromosomes 22 and 29) and taurine (26 SNPs on chromosome 22). Importantly, the top two SNPs for taurine were highly significant (p = 6.2 × 10-21 ), and the frequency of the increase-concentration allele (Q) for taurine was found to be 0.73. The Q allele frequency of this population was similar to that of the other unrelated Japanese Black cattle, but different from that of the other breeds. In addition, the significant SNPs were not associated with carcass traits or fatty acid compositions. Interestingly, the top three of the four most significant SNPs for taurine were located near solute carrier family 6, member 6 (SLC6A6), which is a membrane transporter for taurine. We also found two associated variants in the 5'-upstream region of SLC6A6; however, they were less significantly associated than the SNPs from the BovineSNP50 array.

Estimates of genetic parameters for chemical traits of meat quality in Japanese black cattle.

Genetic parameters for 54 carcass and chemical traits, such as general composition (moisture, crude fat and crude protein), fatty acid composition and water-soluble compounds (free amino acids, peptides, nucleotides and sugars) of 587 commercial Japanese Black cattle were assessed. Heritability estimates for carcass traits and general composition ranged between 0.19-0.28, whereas those for fatty acid composition ranged between 0.11-0.85. Most heritability estimates for water-soluble compounds were lower than 0.30; these traits were affected by aging period. Moderate heritability was observed for glutamine, alanine, taurine, anserine, inosine 5'-monophosphate (IMP), inosine and myo-inositol. In particular, heritability estimates were the highest (0.66) for taurine. Traits with moderate heritability were unaffected by aging period, with the exception of IMP, which was affected by aging period but exhibited moderate heritability (0.47). Although phenotypic correlations of water-soluble compounds with carcass weight (CW), beef marbling standard (BMS) and monounsaturated fatty acid were generally low, genetic correlations between these traits were low to high. At the genetic level, most of the water-soluble compounds were positively correlated with monounsaturated fatty acid but negatively correlated with CW and BMS. Thus, our results indicate that genetic variance and correlations could exist and be captured for some of the water-soluble compounds.

Genome-wide association study for carcass traits, fatty acid composition, chemical composition, sugar, and the effects of related candidate genes in Japanese Black cattle.

We performed a genome-wide association study (GWAS) and candidate gene analysis to: (i) evaluate the effectiveness of the GWAS in our small population by performing GWAS for carcass weight (CW) and fatty acid composition; (ii) detect novel candidate regions affecting non-CW carcass traits, chemical composition and sugar; and (iii) evaluate the association of the candidate genes previously detected in CW and fatty acid composition with other economically important traits. A total of 574 Japanese Black cattle and 40 657 Single nucleotide polymorphisms were used. In addition, candidate gene analyses were performed to evaluate the association of three CW-related genes and two fatty acid-related genes with carcass traits, fatty acid composition, chemical composition and sugar. The significant regions with the candidate genes were detected for CW and fatty acid composition, and these results showed that a significant region would be detectable despite the small sample size. The novel candidate regions were detected on BTA23 for crude protein and on BTA19 for fructose. CW-related genes associated with the rib-eye area and fatty acid composition were identified, and fatty acid-related genes had no relationship with other traits. Moreover, the favorable allele of CW-related genes had an unfavorable effect on fatty acid composition.

Search for an index for the taste of Japanese Black cattle beef by panel testing and chemical composition analysis.

To search for an index for chemical composition related to superior taste in Japanese Black beef, we conducted panel tests and analyzed the chemical composition of seven beef brands. Thirty-five sirloin beefs from five heifers were used in this study, sold under seven beef brands graded as more than A4 on the Japanese Meat Grade scale. The chemical composition analyses assessed both raw and roasted meat, the latter of which was roasted under the same conditions as those used for the panel test. Results of the panel test and chemical composition analyses revealed that fatty acid composition, sugar content, adenosine triphosphage (ATP)-related compounds, amino acid composition and odor composition in the sirloin meat differed among beef brands. Furthermore, the correlations of chemical compositions between roasted and raw meat were significantly high. Sugar content and ATP-related compounds in roasted meat were significantly correlated with the item 'overall evaluation' of the panel test. ATP-related compounds, such as inosinic acid, carnosine and taurine, in roasted and raw meat were correlated significantly with the item 'umami intensity' of the panel test. These results suggest that the composition of these components is important for an index related to the overall evaluation of beef.

Genome-wide association studies reveal additional related loci for fatty acid composition in a Duroc pig multigenerational population.

The aim of the present study was to detect quantitative trait loci affecting fatty acid composition in back fat and intramuscular fat in a Duroc pig population comprising seventh-generation pedigrees using genome-wide association studies (GWAS). In total, 305 animals were genotyped using single nucleotide polymorphisms (SNPs) array and five selected SNPs from regions containing known candidate genes related to fatty acid synthesis or metabolism. In total, 24 genome-wide significant SNP regions were detected in 12 traits, and 76 genome-wide suggestive SNP regions were detected in 33 traits. The Sus scrofa chromosome (SSC) 7 at 10.3 Mb was significantly associated with C17:0 in intramuscular fat, while the SSC9 at 13.6 Mb was significantly associated with C14:0 in intramuscular fat. The SSC12 at 1.0 Mb was significantly associated with C14:0 in back fat and the SSC14 at 121.0 Mb was significantly associated with C18:0 in intramuscular fat. These regions not only replicated previously reported loci containing some candidate genes involved in fatty acid composition (fatty acid synthase and stearoyl-CoA desaturase) but also included several additional related loci.

Genomic evaluation using SNP- and haplotype-based genomic relationship matrices in a closed line of Duroc pigs.

A simulation analysis and real phenotype analysis were performed to evaluate the impact of three different relationship matrices on heritability estimation and prediction accuracy in a closed-line breeding of Duroc pigs. The numerator relationship matrix (NRM), single nucleotide polymorphism (SNP)-based genomic relationship matrix (GRM) (GS ), and haplotype-based GRM (GH ) were applied in this study. We used PorcineSNP60 genotype array data (38 114 SNPs) of 831 Duroc pigs with four selection traits. In both heritability estimation and prediction accuracy, the accuracy depended on the number of animals with records. For heritability estimation, a large difference in the results among three relationship matrices was not shown, but the trend of the estimated heritabilities between GRMs, that is GS  < GH , was shown in this population. For the accuracy of prediction values in test animals, the accuracies of prediction values obtained by two GRMs were higher than that by the NRM in this population. The accuracies obtained by GRMs using animals with no records were lower than that by the NRM using animals with their performance records, but were close to that by the NRM using animals with full-sib testing records.