The Lab Rat Bares Its DNA to Biologists
Travis, J., Science News
Overshadowed in scientific circles for the past few decades by its smallish cousin the mouse, the rat is back in the limelight. This week, biologists announced that they have deciphered the full DNA sequence of the standard lab rat, setting the stage for a new flurry of biomedical research on this rodent and providing insight into mammalian evolution.
People and rats have a long history together, not all of it happy. The Chinese made the animal the first sign of their zodiac, but others have called it the devil's lapdog and blamed it for spreading the plague.
Scientific studies of laboratory-raised rats began in the early 1800s, many decades before researchers began to seriously investigate mice. Since then, researchers have identified or bred hundreds of rat strains that suffer conditions mimicking human diseases such as high blood pressure, obesity, diabetes, cancer, and arthritis.
The mouse's genes, however, proved easier to study and modify, so scientists deciphered the entire mouse DNA sequence, or genome, before turning to the rat. "The mouse has gotten a lot of good press, but the rat really is the workhorse of biomedical research," says Richard Gibbs of Baylor College of Medicine in Houston.
In the April 1 Nature, Gibbs and an international team of more than 100 scientists unveiled the genome of the albino laboratory strain of the rat called brown Norway (Rattus norvegicus). Also, the April Genome Research features about 30 papers in which different groups of the same researchers analyze the rodent's DNA in various ways.
According to the Nature report, the rat genome contains less DNA than the human genome does but slightly more than the mouse genome. All three species possess similar numbers of genes, perhaps as few as 25,000, the scientists say. …