Identification of splice variants,expression analysis and single nucleotide polymorphisms of the PRMT2 gene in dairy cattle

Protein arginine N-methyltransferase 2 (PRMT2), also named HRMT1L1, belongs to the Bovine Protein arginine N-methyltransferase (PRMT) genes which are involved in the immune response. To explore the variability of the PRMT2 gene and resistance to mastitis in cows, splice variant (SV), and single nucleotide polymorphisms (SNPs) were identified in this study. A SV (PRMT2-SV) lacking exon 7 (98-bp) of the PRMT2 gene was found in healthy and mastitis-infected mammary gland tissues. Two of four SNPs were significantly associated with bovine milk yield and protein content. Further, we estimated the relative expression of PRMT2-SV in the mammary gland tissue of dairy cattle by using quantitative real-time polymerase chain reaction. The result showed that expression of the PRMT2-SV mRNA was significantly upregulated 4.02-fold (p < 0.05) in infected mammary tissues (n = 5) compared to healthy tissues (n = 5). Our findings reveal that PRMT2-SV may play an important role in mastitis resistance in dairy cattle. The SNPs may be used as a possible candidate SNPs for marker-assisted selection and management in Chinese Holstein cattle.     

ZBTB38 gene polymorphism associated with body measurement traits in native Chinese cattle breeds

Body measurement traits, influenced by genes and environmental factors, play numerous important roles in the value assessment of productivity and economy. In this study, we investigated the association between genetic polymorphisms of the zinc finger and BTB domain containing 38 gene (ZBTB38) and body measurement traits in native Chinese cattle. Using direct DNA sequencing in 423 individuals of 8 different cattle subpopulations, 9 novel polymorphisms were identified for genotyping within 647 bp region of exon 1 of ZBTB38. Linkage disequilibrium and association analysis revealed that two coding exon polymorphisms (2323 G>A and 2325 C>T polymorphisms), missense mutations valine GTC(T) to isoleucine ATC(T), were associated with body length (BL), withers height (WH) and rump length (RL). Furthermore, the analysis of 2323 G>A and 2325 C>T SNP markers shows that there are significant effects on the BL (P = 0.0488), WH (P = 0.0044) and RL (P = 0.0314) in the total population. These results clearly suggest that the ZBTB38 gene is among the target genes for body measurement traits in bovine breeding, and provide data for establishment of an animal model using cattle to study big animal body type.     

Bovine CLEC7A genetic variants and their association with seropositivity in Johne's disease ELISA

Mycobacterium avium ssp. paratuberculosis (MAP) infection in cattle causes significant economic losses to the dairy and beef industries resulting from reduced productivity, premature culling and mortality. Bovine Dectin-1, an important pattern recognition molecule that is able to generate a proinflammatory response by acting alongside Toll like receptor (TLR) signaling, is known to co-operate with TLR2 to specifically activate a macrophage proinflammatory response against mycobacterial infections. Therefore, the goal of this study was to identify single nucleotide polymorphisms (SNPs) in the gene encoding bovine Dectin-1 (CLEC7A) and to assess their association with susceptibility to MAP infection in dairy cattle. Blood and milk samples, collected from commercial dairy operations, were tested for MAP infection using blood and milk ELISAs and a resource population consisting of 197 infected and 242 healthy cattle was constructed. Pooled DNA was used for sequencing and eight single nucleotide polymorphisms (SNPs) were identified. Identified SNPs were genotyped on the resource population using the iPLEX MassARRAY system and statistical analysis was performed using logistic regression fitting the additive and dominance effects of each SNP in the model. Out of a total of eight identified SNPs, five were successfully genotyped, and three out of these five SNPs were found to be in complete linkage. Statistical analysis revealed a strong association between a non-synonymous SNP c.589A>G (p = 0.008), and MAP infection status of the resource population inferred by seropositivity in MAP antibody specific ELISAs. This SNP c.589A>G was located in the geneic region that encodes the carbohydrate recognition domain of bovine Dectin-1. Therefore, further investigation of its functional relevance is warranted.     

Promoter variants at AP2 box region of Hsp70.1 affect thermal stress response and milk production traits in Frieswal cross bred cattle

Heat shock proteins (Hsp) are known to play major role in protection of cells from thermal stress. Nucleotide polymorphisms within the promoter of Hsp affect degree of expression and inducibility of Hsp mRNA. The present study aimed to investigate the effect of polymorphism within promoter region on the cellular expression of Hsp70.1 mRNA and association of identified polymorphisms with the physiological parameters during summer stress and milk production traits in dairy cattle. Two hundred Frieswal cows were genotyped using double PCR-RFLP to identify deletion of cytosine within the Hsp70.1 promoter AP2 box at base position 895. Homozygous wild type genotypes (CC) were found in lower frequency (39.29, n = 78) than heterozygous cytosine deletion mutant genotypes (C −) (60.71, n = 122). In the observed physiological parameters (rectal temperature, respiration rate and heat tolerance coefficient), cows that were homozygous wild types had better significant (P < 0.05) summer tolerance than the heterozygous deletion genotypes. Cytosine deletion mutation in the promoter region negatively affected (P < 0.01) the expression of Hsp70.1 mRNA in peripheral bovine mononuclear cells (PBMC) subjected to in vitro heat stress. Further association of observed polymorphism with the milk production traits was significant as the heterozygous cytosine deletion cows had lower total milk yield, peak yield, yield at 300 days, protein% (P < 0.01) and fat% (P < 0.05) than the native wild type promoter cows. The results from the present study suggest that the promoter region of bovine hsp70.1 gene is polymorphic and may be useful in selection of dairy cows for relatively better thermotolerance and higher milk production.     

The Adiponectin variants contribute to the genetic background of type 2 diabetes in Turkish population

Adiponectin, an adipose tissue specific protein encoded by the Adiponectin gene, modulates insulin sensitivity and plays an important role in regulating energy homeostasis. Many studies have shown that single nucleotide polymorphisms (SNPs) in the Adiponectin gene are associated with low plasma Adiponectin levels, insulin resistance and an increased risk of type 2 diabetes mellitus. The aim of the present study was to evaluate the contribution of the Adiponectin gene polymorphisms in genetic background of type 2 diabetes in a Turkish population. In total, 169 unrelated and non-obese diabetic patients and 119 age- and BMI-matched non-diabetic individuals with no family history of diabetes were enrolled in this study. We detected a significant association between type 2 diabetes and two SNPs: SNP − 11391G > A, which is located in the promoter region of the Adiponectin gene, and SNP + 276G > T, which is found in intron 2 of the gene (P < 0.05). The silence SNP G15G (+ 45T > G) in exon 1 and SNP + 349A > G in intron 2 also showed a weak association with type 2 diabetes (P = 0.06 and P = 0.07, respectively), while SNPs − 3971A > G in intron 1 and Y111H, R112C and H241P in exon 3 showed no association (P > 0.05). In conclusion, these findings suggest that Adiponectin gene polymorphisms might be effective on susceptibility for type 2 diabetes development which emerged from the interactions between multiple genes, variants and environmental factors.     

Proopiomelanocortin gene polymorphisms and its association with meat quality traits by ultrasound measurement in Chinese cattle

Ultrasound technology was used to measure live animal meat traits instead of true carcass meat traits for beef production and cattle breeding by an increasing number of institutions. In this study, we analyzed the association between genetic polymorphisms of proopiomelanocortin (POMC) and ultrasound measurement traits in Chinese cattle. Using direct DNA sequencing in 322 individuals of 7 different cattle subpopulation, 7 SNPs were identified for genotyping within 790 bp region of intron 2 and exon 3 of POMC. 6586 T>G in intron 2 and 6769 C>T and 7216 C>T in exon 3 were significantly associated with ultrasound backfat thickness (UBF) (P < 0.05) and ultrasound loin muscle area (ULMA) (P < 0.01) in the total population; 6694 C>T, 6706 T>C, 6796 C>T and 6810 C>T in exon 3 were significantly associated with ULMA (P < 0.0001) in the total population. These results clearly suggest that these SNPs of POMC be benefit for selection of individuals with good quality meat in Chinese cattle breeding program. Following validation in other populations and breeds, these markers could be incorporated into breeding programs to increase the rate of improvement in carcass and meat quality traits.