FISH MAPPING OF THE IGF2 GENE IN HORSE AND DONKEY - DETECTION OF HOMEOLOGY WITH HSA11

Three genomic subclones derived from a phage clone containing the equi ne IGF2 gene were used to FISH map the gene on horse (EGA) and donkey (EAS) metaphase chromosomes. The gene mapped on ECA 12q13 band and is the first locus mapped to this horse chromosome. In donkey the gene ma pped very terminal on the long arm of one small submetacentric chromos ome that shows almost identical DAPI-banding pattern with ECA12. This is the first locus mapped in donkey genome. Cross species chromosome p ainting of equine metaphase chromosomes with human Chromosome (Chr) 11 -specific probe showed homoeology of this human chromosome with ECA12 and ECA7. The novel ECA12 comparative painting results are thus in acc ordance with the localization of the equine IGF2 gene. Comparison of t he hitherto known physical locations of IGF2 in different species, viz . human, cattle, sheep, horse, and donkey, shows that this gene tends to maintain a terminal location on the chromosome arm.