Screening for K-Casein (CSN3) Gene Variation in Carpathian Goat Breed by Isoelectric focusing (IEF) and DNA Sequencing

Abstract

In goats, k-casein (CSN3) locus is highly polymorphic with up to 16 allele currently characterized. They produce 13 protein variants (CSN3) that were classified in two groups (AIEF and BIEF), according to their isoelectric point. Isoelectric focusing (IEF) of milk samples allows the detection of these two CSN3 groups, but for correct identification of CSN3 alleles DNA based genotyping methods are needed. Therefore the objective of this study was to identify the types of alleles occurring at the CSN3 locus in Carpathian goat breed by using a combined IEF and DNA sequencing approach. IEF analysis of milk samples collected from two Carpathian goat populations reared in Romania revealed two distinct CSN3 patterns. Amplification and sequencing of CSN3 cDNA obtained from these goats revealed four polymorphic sites located in the exon 4 that are responsible for amino acids substitutions, as compared with the reference sequence of A allele. By comparative analysis of IEF and cDNA sequencing data obtained from the two populations, we shown that AIEF alleles are represented by B allele, while BIEF alleles are represented by D allele. However, the variation of CSN3 locus in Carpathian goat breed could be more complex, therefore further studies are needed to characterize it.

Keywords

• alleles
• carpathian goat
• genetic polymorphism
• k-casein