quote:
Scots scientists challenge rules of evolution
Frank Urquhart
A MAJOR discovery of a so-called missing link by researchers at a Scottish university has raised serious doubts about how the cells in the human body and other forms of life first evolved.
Until now, it has been accepted thinking among biologists that the complex cells of the human body evolved from primitive cells such as bacteria. These contained only a tiny specialised nucleus which held and protected the genes of every cell.
Only later in evolution, it was believed, did cells acquire hundreds of mitochondria - the minute energy generators which power and keep complex cells alive.
But that view is now being challenged by scientists at Dundee University and researchers at the National History Museum in London, who have used state-of-the-art microscopy techniques to identify an unexpected link in the evolutionary process.
They have discovered tiny mitochondria lying undetected in the cells of primitive parasites.
Dr John Lucocq, of Dundee University, said the team’s discovery represented a new missing link in scientific knowledge.
He added: "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."
He said his team began to have doubts about accepted scientific thinking when recent research suggested that the typical components of a cell’s "power pack" - mitochondria - might be present in primitive cells. Advanced microscopy techniques confirmed their suspicions.
Dr Lucocq said: "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."
He added: "This discovery 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."--The Scotsman
Or if you want the nature article, it is
here
[This message has been edited by blitz77, 09-08-2002]
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