Rat genome reveals supercharged evolution
18:00 31 March 04
Roughly 200 years after being tamed, bred and adopted as
science's favourite laboratory animal, the brown Norway rat
has had its genome sequenced. It is only the third mammal
after humans and mice to have its genetic plan read.
Researchers say the feat will allow important human genes to
be tracked down more quickly, for example those related to
cardiovascular disease or behaviour, and will speed the
creation of treatments for diseases.
Comparisons between the genomes is also yielding tantalising
insights into how each species evolved. The analysis has
already shown, for example, that rats have been evolving
faster than both humans and mice. "We find that rodent
evolution is an order of magnitude faster than in humans,"
says Richard Gibbs of the Baylor College of Medicine in
Houston, Texas, and head of the sequencing effort.
The regions evolving fastest are those associated the rat's
acute sense of smell and its use in detecting danger,
marking territory and choosing mates. Rats have an estimated
2070 smell receptor genes, about a third more than mice, and
also make more "pheromone" scents.
Smelly pipes
Rats have also zoomed ahead in the evolution of genes that
help them detoxify chemicals in their livers and elsewhere.
"Rats occur in smelly sewer pipes and yucky places, as
compared with the mouse living in nice clean fields, and
that fits the model of how their genes develop," Gibbs says.
By "knocking out" genes, it might be possible to genetically
engineer rats so that their detox machinery is identical to
ours, improving the predictive accuracy of toxicology and
drug safety testing.
Similarities between the human and rat genomes are as
important as the differences. Researchers were relieved to
find that almost all the human genes linked with disease so
far are identical in rats too, validating the use of rats in
their experiments.
The availability of the draft rat genome, covering 90 per
cent of its genetic code, should accelerate research on the
genetic roots of inherited disorders in humans.
"The identification of disease genes will in many cases be
five fold quicker with a [rat] genome sequence," says
Kerstin Lindblad-Toh, at MIT's Whitehead Institute in
Cambridge Massachusetts.
Read the rest at NewScientist
newscientist.comnews.jspOpen ↗
Posted by Robert Karl Stonjek.