Two novel SNPs identified in STAT1 gene adjoining a QTL for milk production in Holstein Friesian crossbreds of Kerala.

We analyzed the effect of a single nucleotide polymorphism, g. C3141T in the 3' UTR of Signal transducer and activator of transcription-1 gene (STAT1) on milk production traits in the Holstein Friesian crossbred cattle of Kerala (n = 144) by association analysis and expression study. The population was genotyped by restriction fragment length polymorphism using Pag1. Association study using the General Linear Model-Analysis of Variance revealed that none of the yield or composition traits analyzed were significantly differed. The expression profile of STAT1 gene in leucocytes of animals bearing homozygous genotypes was compared by quantitative real time PCR using SYBR green chemistry with and relative expression was not found to be significantly differed. The second stage of the study, the STAT1 mRNA spanning 3213 bp was amplified from leucocytes and sequenced (GenBank: MT459802.1). Two novel SNPs were identified; one synonymous mutation in the coding region (g.A1212G) and the other in the 3'UTR (g.T3042C). The novel SNPs might contribute to STAT1 gene regulation mediated by alternate spicing or binding sites for regulatory molecules. The results reiterate the importance of extensive studies of STAT1 gene variants to substantiate the presence of a quantitative trait loci for dairy traits in the vicinity of STAT1 gene.

High resolution melt curve analysis identifies a novel SNP (G21A) in butyrophilin gene having significant association with milk production traits in Holstein Friesian crossbreds of Kerala.

Butyrophilin (BTN1A1) gene is located in the neighborhood of a quantitative trait loci for milk production in bovine autosome 23. We verified the genetic variability of exon-3 in BTN1A1 and its association with milk production traits in Holstein Friesian crossbreds of Kerala. Genomic DNA was isolated and 94 bp fragment enclosing exon-3 was amplified by primers designed using PRIMER 3 based on reference sequence (GenBank NC_037350). Pooled amplicons were sequenced by Sanger's method and a novel single nucleotide polymorphism due to a transversion of guanine to adenine at position 21 of amplicon (G21A) leading to amino acid change arginine to glutamine was detected. The study population was genotyped by high-resolution melt curve analysis and revealed two genotypes with frequencies GG/0.84 and GA/0.14. The allele G was found to be the major one (G/0.93 and A/0.07). Moreover, association analysis of G21A with milk production traits was done using the General linear model-Analysis of Variance considering herd, season, and parity as non-genetic factors and milk production trait as a dependent variable. In analysis, animals with GA genotype were found to be having significantly higher (p ≤ 0.01) 305 day milk (GG:2720.74 ± 122.92 kg; GA:3250.20 ± 183.24 kg), fat (GG:106.55 ± 4.32 kg; GA:126.30 ± 13.35 kg), and SNF yield (GG: 211.52 ± 9.20 kg; GA: 246.90 ± 13.70 kg). However, GG (7.80 ± 0.04) genotype has significantly higher (p ≤ 0.05) SNF percent than GA (7.65 ± 0.07). Butyrophilin gene polymorphism G21A can be suggested as a molecular marker for future breeding programmes of cattle.