Posted on 08/09/2006 5:15:26 PM PDT by Boxen
Palaeontologists have used a particle accelerator to reveal for the first time the structure of 500-million-year-old fossilised embryos.
The researchers harnessed powerful X-ray beams from a synchrotron particle accelerator to create three-dimensional scans of embryos from two worm-like species from the Cambrian period called Markuelia and Pseudooides.
The scans revealed previously unseen growth mechanisms for the worms' segments and provided further evidence of their evolutionary significance, says Philip Donoghue of the University of Bristol, UK, who led the research team (Nature, vol 442, p 680). "This imaging technology is truly stupendous. It could revolutionise the study of fossils," he says.
Until now, scientists have been limited to studying only the exterior surfaces of such fossils using electron microscopy, or else damaging the precious fossils by cutting out 2D slices. Medical CT scanners can only resolve detail down to 1 millimetre - no use with fossil embryos around 1 millimetre wide.
So Donoghue and his colleagues acquired some free "beam time" on the Swiss Light Source synchrotron, based at the Paul Scherrer Institute in Villigen. The SLS uses a magnetic field to force electrons to fly around a ring, causing them to emit radiation at infrared and X-ray wavelengths. By filtering this radiation to eliminate the noise created by different X-ray wavelengths interfering with each other, the device creates a single-wavelength X-ray beam up to a billion times more brilliant than those used in CT scans.
The team rotated the fossil embryos in the X-ray beam to create a full 3D virtual model of each one's structure that they could rotate and examine as they wished. This gave them the first 3D glimpse of embryological cell development. By studying many hundreds of fossils, the team could resolve minute differences at various developmental stages.
"We found a new pattern for making embryonic segments in the developing embryo - patterns not seen in living animals," says Donoghue. In addition, he and his colleagues found firmer evidence that the worm-like Markuelia is a close relative of the common ancestor of Drosophila flies, and nematodes. "This is a huge deal because it's the common ancestor of two of the most important genomic and embryological models used in biomedical research today," he says.
Andrew Knoll, a palaeontologist at Harvard University who in 2003 used synchrotron X-rays to uncover microscale water-conducting cell structures in early plant fossils, says the technique provides a level of 3D cellular information that is not available with other types of analysis.
For your list.
Hopefully the data is secure.
And here I was expecting a thread about Illbay or Cultural Jihad.
does it bring light to the Kerry species?
Silence of the Worms: a new movie.
"Evolution of a penis worm"
I am NOT clicking that XXX link
Dude, you just revved up the Wayback Machine with those two!
How about CarolHuTex or whatever her name was? Remember that freak of nature?
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