Scientists at the University of Dundee have made a discovery which challenges accepted thinking on how body cells evolved. Working with colleagues from the National History Museum in London they have used state of the art microscopy techniques to identify an unexpected link which calls into question the origins of our body cells.
Scientists believe that the complex cells of our body evolved from simple cells like bacteria. Primitive cells first evolved a tiny specialised compartment called a nucleus - which is basically a bag for holding and protecting the genes of every cell. Only later in evolution did they acquire hundreds of minute energy generators that keep our complex cells alive - better known to biologists as mitochondria. The main evidence for these two steps in evolution came from primitive parasite cells that contain a nucleus but show no traces of the power generating mitochondria.
Now a team at the University of Dundee School of Life Sciences, working with scientists at the Natural History Museum in London, have thrown light on this problem. Dr John Lucocq from the University of Dundee explains: "So far no one had seen mitochondria in these parasites but we became suspicious when a recent project suggested typical components of mitochondria might be present. We used powerful state of the art high resolution electron microscopes at the University of Dundee to reveal mitochondria that were less than ten times smaller than the mitochondria of other cells. We now think the tiny mitochondria of these parasites are "left overs" that have shrunk during evolution making them more difficult to recognise".
This discovery, which is reported in this weeks Nature magazine, changes the way we think about how cells evolved. If these parasites are a sort of living fossil, then this is a bit like a "missing link" human ancestor turning out to be a present day human. As a result a group of microorganisms once thought to be primitive have turned out to be degenerates.
In an accompanying News and Views article in Nature magazine Andrew J. Roger of Dalhousie University in Halifax, Nova Scotia, Canada, and Jeffrey D. Silberman, of the University of California at Los Angeles discusses the implication for our understanding of microbial cell biology and evolution./ENDS