Biotechnology

Biography

Biography: Vishnu Kumar

Abstract

The present investigation was undertaken to explore the new allelic variants of DRB3.2 and to find out their association with mastitis tolerance and susceptibility. A total of 100 lactating crossbred cattle maintained at Cattle and Buffalo Farm, IVRI, Izatnagar were selected randomly. All the selected animals were screened by CMT as well as SCC and classified into two groups’ viz., mastitis tolerant and mastitis susceptible. DNA was isolated from collected blood samples. Isolated DNA having good quality and purity was used for further analysis. By using previously reported primers, amplification of 284 bp region of DRB3.2 was carried out by standard PCR protocol at specific annealing temperature. Denaturing PAGE of PCR product was carried out and SSCP patterns were visualized by silver staining. Genotyping of each animal was performed manually and two types of genotypes viz., AA and AB were determined by SSCP analysis. Genotype and gene frequency for both genotypes and alleles were estimated. Statistical analysis was done by using two way classification interaction model for SCC and logistic regression for mastitis incidence. PCR products having amplified fragment of exon 2 of DRB3 gene were sent for sequencing. In the present study, genotype AB was found predominant in mastitis tolerant animals, whereas allele A was predominant in all animals. Analysis of variance for SCC revealed that both DRB3.2 genotypes had significant effect on SCC. Logistic regression showed that genotype AA was highly significant for mastitis incidence in comparison to genotype AB. Two SNPs in allele A and four SNPs in allele B were detected in DRB3.2 gene by sequence analysis and these mutations changed amino acid sequences. Thus, it can be concluded that exon 2 of DRB3 gene was found polymorphic in crossbred cattle with two new alleles associated with mastitis.