Invivo restoration of DNA function from an extinct genome
First saw this article on A blog around the clock and found it very interesting and thought of sharing the same on my blog.Recently PLOS ONE has published an article on Invivo restoration of DNA function from an extinct genome.DNA from Tasmanian wolf which was ethanol-fixed and stored for over 100 years in Museum was used .
Australian scientists has brought back the fragment of DNA from a extinct specie of Marsupial (Thylacinus cynocephalus or thylacine) back to life.In order to resurrect the non coding DNA from the extinct animal they first isolated genomic DNA from the preserved organisms,which was fragmented as expected.Researchers chose to isolate the well-characterised transcriptional enhancer element of the proa1(II) collagen (Col2a1) gene as it was very well conserved among mammals and directs chondrocyte-specific expression in the mouse.With help of PCR finally they managed to clone 264bp region containing the enhancer.Phylogenetic analyses of the thylacine sequence with that of eutherian and marsupial species confirmed its identity as the thylacine Col2a1 enhancer orthologue. The cloned enhancer was tested in transgenic analysis in Mice by cloning four copies of enhancer ( for increasing the strength) ligated to human b-globin basal promoter fused to lacZ and followed by a polyadenylation signal.Transgenic animals obtained after injecting the purified construct in pronuclei of mouse zygotes.LacZ staining were observed in in all 4 founder fetuses created in a pattern indicative of developing cartilage,which was identical to Mouse endogenous Col2a1 gene and mouse enhancer transgenes.This confirms that the thylacine Col2a1 gene had a conserved developmental role in cartilage formation. It also suggests that the associated transcription factors and the minimal enhancer element required for inducing expression from this promoter have remained sufficiently conserved between mice and marsupials to direct expression despite approximately 148 million years of divergent evolution between these species.
Image source and Reference:
Pask AJ, Behringer RR, Renfree MB (2008) Resurrection of DNA Function In Vivo from an Extinct Genome. PLoS ONE 3(5): e2240. doi:10.1371/ journal.pone.0002240
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