Transcriptionally quiescent spermatozoa have been established to be a repository of mRNA coding for several functionally essential cellular proteins. This entourage of mRNA is envisaged to be involved in post-fertilization and early embryogenesis. Minisatellites tagged with mRNA transcripts have been implicated with gene organization, regulation and function. However, the organization and expression of the minisatellite tagged transcript diversity, particularly in spermatozoa, remains unclear.
In the present study, we identified and characterized 12 mRNA transcripts from the spermatozoa of water buffalo Bubalus bubalis employing minisatellite associated sequence amplification (MASA) and a consensus sequence of 33.15 repeat loci. Of these 33.15 tagged transcripts, only one was found to be homologous to Bovine steroid 21-hydroxylase (P-450-c21) gene. Other ten transcripts showed significant similarity with various mRNAs or chromosomal contigs across the species. The remaining one construed to be novel since this was unreported in the database (NCBI GenBank). All these uncharacterized and known transcripts showed highest expression in testis and spermatozoa compared to that in somatic tissues and ovary. Of these 12 mRNA transcripts, 4 showed differential expression in the forebrain and hindbrain of buffalo. Moreover, genes corresponding to all the 33.15 tagged spermatozoal transcripts were found to be conserved across 13 other species analyzed.
Our results show MASA as an important tool to capture mRNA transcript diversity tagged with minisatellites in the spermatozoa. Comprehensive characterization of these transcripts is envisaged to augment our understanding on the genes involved in testicular functions and sustenance of a viable paternal genome during pre- and post- fertilization events and early stages of development. Prospects of this approach in genome analysis in general and comparative genomics in particular are highlighted.