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As one of the eight members in the 1-acylglycerol-3-phosphate-O-acyltransferase (AGPATs) family, AGPAT6 is a crucial enzyme for the biosynthesis of glycerolipids and triacylglycerol in eukaryotes, as well as catalyzing the conversion from lysophosphatidic acid to phosphatidic acid. AGPAT6 can be considered as a candidate gene for regulating milk composition. DNA sequencing and PCR-RFLP methods were applied to detect genetic variation in the AGPAT6 gene in 549 Chinese dairy goats. Four polymorphisms (NC&#95;007328.3:g.152G>C, 8124G>A, 9263C>G, 16436G>A) were detected in 5'UTR, intron 2, exon 4, and 3'UTR, respectively. For the KpnΙ locus, the frequencies of the AGPAT6-G allele were 0.955 and 0.936 for SN (Xinong Sannen) and GZ (Guanzhong) dairy goat breeds, respectively. In the PCR-RFLP analysis for KpnΙ, EcoRII, NcoΙ, and BglΙ, the frequencies of the G allele of AGPAT6 were 0.955 and 0.936, 0.694 and 0.819, 0.206 and 0.254, 0.729 and 0.623 for SN and GZ dairy goat breeds, respectively. The 9263C>G mutation revealed a synonymous genetic code of Thr (threonine). Associations between the four mutations and milk traits were analyzed in two dairy goat breeds. At the 9263C>G locus, genotype GG and CG individuals showed significantly better milk performance than genotype CC individuals (P < 0.05). Therefore, the G allele is suggested to be a molecular marker for milk production in dairy goats.

Milk composition and body measurement traits, influenced by genes and environmental factors, play important roles in value assessments of efficiency and productivity in dairy goats. Lactoferrin (LF), involved in the efficient expression of protein in milk, is also an anabolic factor in skeletal tissue and a potent osteoblast survival factor. Therefore, it is an important candidate gene for milk composition and body measurement trait selection in marker-assisted selection. We employed PCR-SSCP and DNA sequencing to screen the genetic variations of the LF gene in 549 Chinese dairy goats. A novel single-nucleotide polymorphism (SNP) (G198A in exon II) of the LF gene was detected. The frequencies of the AA genotype were 0.0285 and 0.0261 in GZ and SN populations, respectively. Both populations were found to have low levels of polymorphism and were in Hardy-Weinberg disequilibrium (P < 0.05). We found significant (P < 0.05) associations of the SNP marker with milk protein and acidity in the total population; animals with the AA genotype had higher mean values for milk protein than those with the GA genotype. Animals with genotype AA had higher mean values for withers height than those with genotype GG (P < 0.05). We concluded that this SNP of the LF gene has potential as a genetic marker for milk composition and body traits in dairy goat breeding.

Myopalladin (MYPN) is a multifunctional protein that maintains sarcomeric integrity and regulates Z-line structure. It is an important candidate gene for meat quality selection through marker-assisted selection. Using PCR-RFLP technology, we discovered a single-nucleotide polymorphism (SNP) (A1795G in exon 9) of the MYPN gene. Allele frequencies of this SNP were investigated and evaluated by the chi(2) test in 660 cattle populations in China; only the Nanyang population was not in Hardy-Weinberg equilibrium. Gene heterozygosity, effective allele number and polymorphism information content of the bovine MYPN locus in seven populations varied from 0.3888 to 0.4998, 1.6360 to 1.9992, and 0.3132 to 0.3749, respectively. We also looked for a potential association of this SNP with ultrasound traits in 399 individuals and found a significant effect on the ultrasound loin-muscle area. Meat quality traits were analyzed in another 61 Qinchuan individuals to analyze associations with genotype. Animals with the genotype GG had higher mean values for loin-eye area (P < 0.05) and water-holding capacity (P < 0.01) than those with AA or AG genotypes. We conclude that this SNP of the MYPN gene has potential as a genetic marker for meat quality traits in cattle reproduction and breeding.