[PCR-RFLP analysis of the mtDNA Cytb gene in three different horse breeds].

The research involved studying the genetic variations in three different horse breeds using Polymerase Chain Reaction – Restriction Fragment Length Polymorphism (PCR-RFLP) analysis of the mitochondrial DNA cytochrome b (Cytb) gene.

Methodology

• The researchers analyzed the polymorphism or genetic variation within a population within specific genomic loci or the DNA sequence of the mitochondrial Cytb gene in 256 horses.
• The horses were from six different types: Thoroughbred, Sanhe, Wuzhumuqin, Xinihe, Wushen, and Pony. These types included both imported breeds and local breeds.
• The analysis was performed using restriction endonucleases. These are enzymes that cut DNA molecules at specific sites.
• In this study, five restriction endonucleases were used: BamH I, Taq I, Hae III, Rsa I, and Hinc II.
• The products of the endonuclease digestion were visualized using 8% non-denaturing polyacrylamide gel electrophoresis followed by silver staining. This method allows the researchers to visualize fragments of digested DNA based on their size.

Results

• The study found that there was polymorphism, or variation in the DNA sequence, for the restriction endonucleases BamH I and Taq I. This indicates some variability in the Cytb gene in the horses analyzed.
• Seven different restriction patterns were detected, which the researchers sorted into three haplotypes – combinations of differences in the DNA sequence. Two of the three haplotypes, I and III, were identified as the basic haplotypes.

Interpretation

• The researchers concluded from their analysis that the horses came from one female ancestor, inferred from one pattern, namely BamH I-B.
• This conclusion is based on the fact that mitochondrial DNA is inherited maternally, or from the mother. Homogeneity in the patterns of this DNA among the horses therefore implies a common maternal ancestry.