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Open Access Research article

RsaI repetitive DNA in Buffalo Bubalus bubalis representing retrotransposons, conserved in bovids, are part of the functional genes

Deepali Pathak and Sher Ali*

Author Affiliations

Molecular Genetics Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi -110 067, India

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BMC Genomics 2011, 12:338  doi:10.1186/1471-2164-12-338

Published: 1 July 2011

Abstract

Background

Repetitive sequences are the major components of the eukaryotic genomes. Association of these repeats with transcribing sequences and their regulation in buffalo Bubalus bubalis has remained largely unresolved.

Results

We cloned and sequenced RsaI repeat fragments pDp1, pDp2, pDp3, pDp4 of 1331, 651, 603 and 339 base pairs, respectively from the buffalo, Bubalus bubalis. Upon characterization, these fragments were found to represent retrotransposons and part of some functional genes. The resultant clones showed cross hybridization only with buffalo, cattle, goat and sheep genomic DNA. Real Time PCR, detected ~2 × 104 copies of pDp1, ~ 3000 copies of pDp2 and pDp3 and ~ 1000 of pDp4 in buffalo, cattle, goat and sheep genomes, respectively. RsaI repeats are transcriptionally active in somatic tissues and spermatozoa. Accordingly, pDp1 showed maximum expression in lung, pDp2 and pDp3 both in Kidney, and pDp4 in ovary. Fluorescence in situ hybridization showed repeats to be distributed all across the chromosomes.

Conclusions

The data suggest that RsaI repeats have been incorporated into the exonic regions of various transcribing genes, possibly contributing towards the architecture and evolution of the buffalo and related genomes. Prospects of our present work in the context of comparative and functional genomics are highlighted.