Localization of the telomeric (TTAGGG)n sequences in chromosomes of some domestic animals by fluorescence in situ hybridization

Abstract

Fluorescence in situ hybridization analysis was carried out on metaphase preparations of a variety of domestic animal species, viz. pigs, cattle, sheep, river buffaloes, swamp buffaloes, horses, and reindeers, using a PCR generated human telomere repeat probe (TTAGGG)n. Three protocols with different hybridization/washing stringencies were applied. Distinct double spots representing the telomeric sites were observed on either ends of the chromosomes in all the species studied, confirming that one-armed chromosomes are not completely telocentric. In pigs, an interstitial telomeric signal was observed on the 6q22 band of all the individuals examined. Although a random variation in the intensity of signals was observed, it was interesting to note that in one of the five cattle studied, very strong hybridization signals were seen on at least three pairs of chromosomes. In sheep, river buffaloes, and swamp buffaloes, where the biarmed chromosomes are considered to be the result of the fusion of 2-3 one-armed chromosomes of the cattle karyotype, no interstitial telomeric signals were observed.