MicroRNAs are a class of small, endogenously produced, 18 to 24 nucleotides long in length. These are non-coding RNAs that regulate the gene expression at post-transcriptional level. They play important roles in animals and plants by controlling regulatory mechanisms, and likely influencing the output of many protein-coding genes. They generally bind to 3' UTR region of the target sequence which then leads to alterations in the gene expression. They also bind to other regions like coding sequence and 5' UTR but these are less efficient sites of interaction compared to 3'UTR. This alteration in gene expression is either due to repression of translation or mRNA degradation whereby the RNA interference pathway is initiated to eliminate the targeted sequences. Now a days, various computational or bioinformatics databases, tools, and algorithms have been developed to identify the target genes which will be further biologically validated using various techniques like reporter gene assay, qRT-PCR, microarray etc.

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Aim: The present study was undertaken to identify whether single nucleotide polymorphism (SNP) rs109231409 located on mannose-binding lectins 1 (MBL1) gene was associated with mastitis tolerance/susceptibility. Materials and Methods:After grouping 100 Vrindavani crossbred cattle as mastitis positive and negative animals, they were genotyped using polymerase chain reaction (PCR)-restriction fragment length polymorphisms method. Gene and genotype frequencies of different patterns were estimated by standard procedure (POPGENE version 1.32, (University of Alberta, Canada) and statistical analysis was carried out by logistic regression methods using STATA 12 software (StataCorp LP, USA). Results:The 588 bp fragment of MBL1 gene was amplified using PCR. PCR product was digested with ApaI restriction enzyme showed two distinct genotypes viz., GG (311 bp and 272 bp fragments) and GA (588 bp, 311 bp and 277 bp fragments). The gene, genotype frequencies, average heterozygosity, polymorphic information content and χ 2 values for the locus rs109231409 was ascertained. Conclusions:No significant association between SNP "rs109231409" with mastitis tolerance was found. Although there is a lack of association, further studies have to be undertaken in a large population in order to validate the impact of rs109231409 (g.855G >A) on mastitis tolerance.

Tick infestation is a major reason for economic loss in livestock production in the tropical countries. However, animals show variation in resistance and susceptibility to tick infestation. Bos indicus breeds were reported to be more resistant to tick infestation than Bos taurus cattle. The present study aimed to identify polymorphisms in four quantitative trait loci (QTLs) that were stated to be associated with resistance/susceptibility to tick infestation, in a population comprising native Vechur breed (n=45) and crossbred cattle (n=74) of the Kerala Veterinary and Animal Sciences University farms. The QTLs were selected from the Animal QTL Database (https://www.animalgenome.org/cgibin/QTLdb/index). The single nucleotide polymorphisms (SNP) and the QTLs (in parenthesis) used in this study were: rs41661020 (#101148), rs43708490 (#135798), rs41577070 (#135800) and rs29009970 (#135801). Blood samples were collected from the animals, isolated the DNA and used for genotyping and polymorphism study by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism and confirmed by sequencing. The results revealed polymorphic pattern for the SNPs rs41577070, rs41664020, and SNP rs43708490 in both Vechur and cross-bred populations. The SNP rs29009970 was monomorphic in the crossbred cattle, whereas, dimorphic in Vechur. Genotyping was done by direct counting and the allelic and genotypic frequencies were estimated by POPGENE 1.32. Chi-square test revealed that crossbreds and Vechur were in Hardy-Weinberg equilibrium for SNPs rs41577070, rs41664020, and rs43708490, whereas, the SNP rs29009970 showed a significant departure from the equilibrium.