Comparative characteristics of DNA polymorphisms of κ-casein gene (CSN3) in the horse and donkey.

This research aimed to examine genetic variability in a specific gene in four Italian horse populations and a type of donkey, comparing genotype, allele and haplotype frequencies, as well as other genetic metrics. The researchers found varying genetic polymorphisms in the horses depending on the breed, and no genetic variability in the donkey breed studied.

Study Overview and Goals

• The goal of this study was to investigate the genetic variability in a specific gene, the κ-casein gene, in four different populations of Italian horses as well as a sample of Martina Franca donkeys.
• The researchers aimed to estimate and compare such genetic parameters as genotype, allele and haplotype frequencies and various population genetic indices.

Methodology

• The researchers used the PCR-RFLP technique along with two restriction enzymes, PstI and BseYI, for genotyping the selected polymorphisms. The aim was to identify the presence of two polymorphisms, c.-66A>G and c.-36C>A.

Findings

• The researchers found both of these gene loci to be polymorphic in horses, with some variations depending upon the breed. This means that they discovered multiple variants or forms of the gene in the horse populations studied.
• They found no genetic variability in the Martina Franca donkey breed, meaning the same version of the gene was found in all individuals tested.
• It was determined that these polymorphisms in the horses could be the result of natural selection or an unintended outcome of selective breeding processes aimed at enhancing certain physical attributes, such as body size or conformation (the physical build and structure of an animal).

Implications

• From these findings, it can be inferred that these two specific single nucleotide polymorphisms, particularly the c.-36C>A one, could be useful tools for conducting population studies in the future.
• No selective breeding towards milk production was performed for horses, suggesting the observed polymorphisms at milk protein gene locations could be a natural adaptation or unintended consequences of selection for other physical traits.