ABSTRACT
Prolactin (PRL) plays central roles in mammals' reproduction, gland development, milk secretion, and the expression of milk protein genes. In dairy cattle, the PRL gene is a potential quantitative trait locus and genetic marker related to milk performance traits. Here, a total of 586 randomly selected Chinese Holstein cows were genotyped for locus PRL-RsaI. One haplotype block containing eight SNPs was identified in the region from intron 3 to intron 4 of the PRL gene in Chinese Holstein cows. One tag SNP (7545 G â A) was selected to represent the haplotype block defined by the genotypic data. The cows with genotype AA of this tag SNP had a higher milk yield at 305 days (8457 ± 938 kg) than the cows with GA (7537 ± 1278 kg; P < 0.01) or GG (7757 ± 1174 kg; P < 0.05). This suggests that the haplotype block examined in this study contains important markers for milk production traits in Chinese Holstein cows.
Subject(s)
Cattle/genetics , Lactation/genetics , Prolactin/genetics , Quantitative Trait Loci , Animals , Animals, Inbred Strains , Female , Polymorphism, Single NucleotideABSTRACT
The signal transducer and activator of transcription (STAT) genes are responsive to a wide range of cytokines, growth factors, and hormones, and thus control important biological processes. In humans, STAT4 mutations have been identified as genetic markers for rheumatoid arthritis, systemic lupus erythematosus, and primary Sjögren's syndrome, whereas little research has been conducted on bovine STAT4 mutations and their potential effects. Herein, 585 Chinese Holstein cows were used to investigate STAT4 mutations and their effects on milk performance traits. One haplotype block, containing g.95879G>A, g.96013G>C, was identified in intron 20 of the bovine STAT4 gene by restriction fragment length polymorphism-polymerase chain reaction and DNA sequencing. Two single nucleotide polymorphisms were significantly associated with milk yield at 305 days (P < 0.05), and with protein percentage (P < 0.05). Chinese Holstein cows with the haplotype GGGG had higher milk yields at 305 days and lower protein percentages. These results suggest that the 2 single nucleotide polymorphisms of STAT4 could be used as genetic markers for milk performance traits in Chinese Holstein cows.
Subject(s)
Deoxyribonucleases, Type II Site-Specific/metabolism , Introns/genetics , Milk/metabolism , Polymorphism, Genetic , Quantitative Trait, Heritable , STAT4 Transcription Factor/genetics , Animals , Cattle , China , Female , Least-Squares Analysis , Linkage Disequilibrium/genetics , Polymerase Chain Reaction , Polymorphism, Restriction Fragment Length , Polymorphism, Single Nucleotide/geneticsABSTRACT
The melanocortin-4 receptor (MC4R) has important roles in regulating food intake, energy balance, and body weight in mammals. In pigs and cattle, MC4R mutations have been identified as genetic markers for growth and traits. Compared with abundant research conducted on other livestock species, little is known about mutations of the ovine MC4R gene. We investigated the effect of MC4R polymorphisms on birth weight and on 45-day weaning weight in 144 Hu sheep. Four single nucleotide polymorphisms (SNPs; g.1016 G/A, g.1240 T/C, g.1264 G/A, and g.1325 A/G) were identified in the 3ê-untranslated region of Hu sheep MC4R by PCR-single-strand conformation polymorphism and DNA sequencing. A haplotype block, containing g.1240 T/C, g.1264 G/A, and g.1325 A/G, was constructed within the Hu sheep MC4R gene. Four SNPs were found to be significantly associated with 45-day weaning weight, while the haplotype block was significantly associated with birth weight. Hu sheep with the genotypes GG in g.1016 G/A or with the genotype CCAAGG in the haplotype block, had higher 45-day weaning weights. We conclude that these 4 SNPs of the MC4R gene have potential as genetic markers for early growth traits in Hu sheep.