Polymorphism of Alpha S1-Casein Gene in Yankasa Sheep Breed of Mubi, Adamawa State of Nigeria

Abstract

Present study was conducted on five Yankasa breeds of sheep to determine alpha S1-CSNISI casein gene polymorphism. Five blood samples were collected using sterile needle and syringe. All the samples were collected into sample tubes containing ethylene diamine tetraacetic acid (EDTA), placed on an ice in cold-chain container and immediately transported to the laboratory for analysis. Gene extraction was carried out using Quick-DNA Miniprep TM kit. Reverse and forward primers were designed and used to amplify the isolated DNA. Nucleotide sequence was subjected to BLAST search against the NCBI database and a similar sequence NC-0040257.1 was retrieved for comparison. Single nucleotide polymorphism was analysed to ascertain the variation. Multiple sequence alignment was performed using Clustal W and was reconstructed using Multalin. A MEGAx Program incorporated in GenAleX 6.503 was used to construct phylogenetic tree using Nei’s genetic distance and multiple sequence alignment generated in muscle (3.8) which was also used to construct phylogenetic tree within as well as with the reference (NC-040257.1). Results from the analysis revealed that, the extracted DNA were found on chromosome 6, intron 16 and exon 17. The breeds showed total number of polymorphic and monomorphic site of 68 and 600 respectively, and percentage polymorphism of 10.18%. High frequency of 0.733 was observed at position 201. Amino acid substitution in Yankasa sheep breed was 4 at positions 161, 163, 164 and 201, showing the existence of variation in Yankasa species possibly indicating long term chances of survival. CSN1S1 isolated in Yankasa sheep showed polymorphism, genetic variation within and between breeds. In further studies, it is therefore of interest to characterize, genotype and find the allele frequencies of casein gene of Yankasa sheep breed, provide a complete picture about milk protein gene and milk protein variation in order to improve consumer preference.