Genetical and physical assignments of equine microsatellites–first integration of anchored markers in horse genome mapping.

This research article is about a study that was able to physical and genetical assign markers on the equine genome, which enhanced the current understanding of the horse genome. The study successfully isolated and mapped 20 horse microsatellites from a genomic phage library.

Microsatellite Isolation

• The researchers isolated twenty equine microsatellites from a genomic phage library. A phage library is a collection of bacterial viruses used to amplify or express the DNA sequences of interest. Microsatellites, also known as short tandem repeats (STRs), are small regions of DNA that contain repeats of a specific sequence.

Genetical Localization

• Out of the twenty equine microsatellites, nineteen was found to be polymorphic, with most cases showing heterozygosities over 50%. Polymorphic refers to a gene that exists in two or more forms, called alleles, while heterozygosity is a term in genetics that refers to an individual possessing two different alleles of a particular gene.
• The polymorphic markers were mapped onto a Swedish reference family for gene mapping, which included eight half-sib families from Standardbred and Icelandic horse sires i.e., male parents.
• Thirteen of the microsatellites showed linkage to at least one other marker, with a total of 21 markers being involved in these linkages.

Physical Localization

• Using Fluorescent In Situ Hybridization (FISH), a technique that uses fluorescent probes to visualize and map the genetic material in an individual’s cells, 18 of the microsatellites could be assigned to their respective chromosomal regions.
• These assignments were contained across eight equine autosomes: ECA1, 2, 4, 6, 9, 10, 15, and 16. Autosomes are the chromosomes that are not sex chromosomes, and they occur in pairs in somatic cells.

Outcome & Implications

• The results of this research represent a significant expansion of the current knowledge of the equine genome map. This could potentially usher in more targeted and effective genetics-based diagnosis and treatment for various disorders in horses.