Chromosomal localization, copy number assessment, and transcriptional status of BamHI repeat fractions in water buffalo Bubalus bubalis

Abstract

Higher eukaryotes contain a wide variety of repetitive DNA, although their functions often remain unknown. We describe cloning, chromosomal localization, copy number assessment, and transcriptional status of 1378- and 673-bp repeat fractions in the buffalo genome. The pDS5, representing the 1378-bp fragment, showed FISH signals in the centromeric region of acrocentric chromosomes only, whereas pDS4, corresponding to 673 bp, detected signals in the centromeric regions of all the chromosomes. Crosshybridization studies of pDS5 and pDS4 with genomic DNA from different sources showed signals only in buffalo, cattle, goat, and sheep. Real-time PCR analysis uncovered 1234 and 3420 copies of pDS5 and pDS4 fragments per the haploid genome, corresponding to 30 and 68 copies per chromosome, respectively. Analysis of cDNA from different tissues of buffalo with Real-time PCR showed maximum expression of pDS5 and pDS4 in the spleen and liver, respectively. Phylogenetic analysis of these sequences showed a close relationship between buffalo and cattle. The prospect of this approach in comparative genomics is highlighted.