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A newly identified form of DNA - small circles of non-repetitive sequences - may be widespread in somatic cells of mice and humans, according to a study in this week's issue of Science. These extrachromosomal bits of DNA, dubbed microDNA, may be the byproducts of microdeletions in chromosomes, meaning that cells all over the body may have their own constellation of missing pieces of DNA.
"It's an intriguing finding," said James Lupski, a geneticist at Baylor College of Medicine in Houston who did not participate in the research. Most DNA studies use cells drawn from blood, but that snapshot of a person's genome may not be giving a complete picture, Lupski explained, if cells in other organs have their own set of chromosomal snippets missing.
But the findings do not surprise Sabine Mai, who studies genomic instability at the University of Manitoba. Extrachromosomal DNA is a well-studied phenomenon in cells ranging from plants to humans, she says. This research is just renaming an old phenomenon, previously referred to small polydispersed DNA. Small circles of DNA have been identified before, Mai says, though new deep sequencing techniques will allow for a "deeper characterization" of these extrachromosomal snippets.
Anindya Dutta, who studies DNA replication at the University of Virginia, and his colleagues were aiming to investigate intrachromosomal shuffling of genes in mouse brain tissue - where recombination at homologous sequences could create extra loops of DNA - but the widespread nature, size, and sequences of the DNA they turned up surprised them.
Comment: As mentioned in the video it will be interesting to see to what extent the UK Government uses their hosting of the Olympics to continue enforcing the adoption of increasingly draconian population controls.