Scientists decipher rat's genome; humans are next!

The rat, both scourge and servant of mankind, has undergone the ultimate dissection.

An international team from the United States, Europe and Canada has laid bare the rat's genome - a 2.75-billion-letter genetic sequence containing all of the animal's hereditary material - and published its findings today in the journal Nature.

The scientists, who spent close to three years snipping up and reading the genome, say it will be an invaluable tool that should lead to a better understanding of everything from human disease to the evolution of rats, human beings and the cast of creatures in between.

Since most disease-linked human genes have counterparts in the rat, the scientists say the genome should allow them to develop more rat models of human disease - such as cancer and heart disease -- to speed up experimental medicine and drug development, inform canada.com

The rat is the third species to be sequenced to such a degree, after the completed human genome sequence in April 2003 and the draft mouse genome in December 2002.

The data confirm that the laboratory rat is a good choice for medical research. Almost all human genes associated with diseases have counterparts in the rat genome, the researchers wrote in this week's issue of the journal Nature. Having the rat genome along with the mouse and human genomes allows scientists to triangulate, just as mariners triangulate to navigate using the stars and the sun, said Baylor's Richard A. Gibbs, who led the study. That will help show what makes mice different from people, and rats from mice.

"If we have two things we can't really tell how far apart we are. Now that we have a third species, we can see whether the changes are rat changes, mouse changes or human changes," Gibbs said. Gibbs said the map shows distinctions that are already helping to separate the rat from other rodents and especially mice, report washingtonpost.com