Cloning of a DNA repeat element from horse: DNA sequence and chromosomal localization.

This research paper details the cloning and characterization of a DNA repeat element from the horse DNA which was found useful for parentage analysis in horses. The sequence was discovered to be located in specific parts of horse chromosomes.

Clone e4/1 and Its Characteristics

• The DNA repeat element discovered in horse DNA was cloned resulting in clone e4/1. This clone consisted of 32 tandem repeat iterations of a unit repeat of 21-22 base pairs (bp).
• These iterations were initially revealed through the digestion of horse DNA using TaqI, which is a restriction enzyme that cuts DNA at specific sequences. This process was the first step towards the identification and eventual cloning of the DNA repeat element.

Utility of the DNA Repeat Element

• Clone e4/1 was found to produce multilocus DNA fingerprinting profiles. Multilocus DNA fingerprinting is a technique which relies on multiple locations in the genome, providing unique genetic ‘fingerprints’.
• The unique DNA profiles derived from e4/1 allowed for its application in parentage analysis amongst horses, serving as a powerful tool in genetic studies and helping in identifying familial relationships and lineage among individual horses.

Localization of the DNA Repeat Element

• Southern and in situ hybridization studies, along with nucleotide sequencing, were performed to characterize the cloned element and identify its chromosomal location.
• This DNA tandem repeat element, as revealed by in situ hybridization, was localized to be in the centromeres of the acrocentric chromosomes of horses.
• The acrocentric chromosomes are a specific class of horse chromosomes that have the centromere located near one end, causing the chromosome to have a short arm and a much longer arm. In contrast, it was not found in the metacentric class of horse chromosomes where the centromere is centrally located, splitting the chromosome into two arms of roughly equal length.