Scientists uncover the genetic code of mice

Scientists Wednesday announced that they have mapped the genetic code for mice, an accomplishment second in importance only to the mapping of the human genome itself.

The promises are familiar: research that could yield a greater understanding of the fundamental processes of organic life as well as new medical treatments. Yet even as the process of cataloguing genetic information becomes almost routine, scientists stress the significance of this achievement in particular.

Roughly three-quarters of the human and mouse genomes are similar. This, biologists say, not only allows them to study the functions of areas that are alike, but it also lets them probe the differences that have evolved since the two species split during the last days of the dinosaurs.

More important, though, is the simple fact that the mouse is the most common animal in the laboratory. The increased knowledge of the mouse genome is expected to launch new areas of study, which are perhaps the most likely to result in therapies for human illnesses.

"On our list of the genomes that we would like to sequence, No. 2 was the mouse," says Robert Waterston, director of the Genome Sequencing Center at Washington University in St. Louis. "It is probably the most powerful experimental animal."

Specifically, the report in Thursday's issue of Nature confirms that researchers at the Whitehead Institute for Biomedical Research in Cambridge, Mass., have charted 96 percent of the mouse genome. By taking DNA from blood and tissue samples, breaking them into pieces by shaking them, then analyzing the leftover pieces of genetic material with computers, scientists could - after thousands of tests - find out what fits where.

The result, written out, would be a manuscript as big as 200 New York phone books filled with A's, C's, G's, and T's (the letters representing the four elements of the genetic code). All together, it is gobbledygook, even to scientists. But within that broth, biologists can isolate sections that make sense.

Now, with this data finally recorded and open to everyone, scientists can find these key sections in a matter of minutes by computer. Before, researchers wishing to study a specific area would have to go through the whole sequence, which could take years.

Moreover, with nearly complete drafts of both the human and mouse genomes, scientists can begin to explore unexplained differences and similarities. "By finding a corresponding gene in humans, you can find out what it might be doing in humans," notes Richard Mural, a scientist at Celera Genomics in Rockville, Md.

Some researchers have already started this process, using data on the mouse genome assembled by Celera more than a year ago and available by subscription. But the data introduced Wednesday will be freely available worldwide, a distinction the authors are quick to make.

"The ultimate goal is to cure human disease," says lead researcher Kerstin Lindblad-Toh of the Whitehead Institute. "And everyone should be able to help."