WASHINGTON - An international team of scientists announced yesterday that it has completed the genetic map of the mouse, an animal revered among researchers as much as it's reviled by homeowners around the world.
The map, which took more than 200 scientists in six countries three years to make, is being heralded by some scientists as an achievement as important as the decoding of the human genome. The availability of both maps is likely to accelerate the search for treatments for cancer, heart disease, schizophrenia, AIDS and other human ailments.
"Today we celebrate a major landmark in the history of biology and medicine," said Francis Collins, director of the National Human Genome Research Institute. "This is not Mickey Mouse science."
The research was published today in the British journal Nature, which devoted nearly its entire issue to the creature.
The map comes more than a year after Celera Genomics of Rockville drafted its own mouse map. But Celera has made its map available only to paying subscribers. The new map, by contrast, is freely available to all scientists over the Internet.
Scientists have long known that mice are genetically very similar to humans, despite having last shared a common ancestor when dinosaurs roamed the Earth.
For more than a century the mouse has become an increasingly popular stand-in for humans in the laboratory, said Collins, who called the creature "the medical researcher's best friend."
But now scientists are finding out exactly how much alike humans and mice really are.
By analyzing the new mouse DNA map and comparing it with the human one, researchers found that both have about 30,000 genes. In fact, for almost every human gene there seems to be a mouse equivalent - and often vice versa.
"We even have the genes that could make a tail," said Jane Rogers of the Wellcome Trust Sanger Institute in Cambridge, England.
Scientists also counted 300 genes that seemed to be unique to each organism - a not unex- pected find. "Otherwise we'd be small furry animals scurrying around on the floor," quipped Robert Waterston, a geneticist at the Washington University School of Medicine in St Louis.
Mice, scientists found, have more genes devoted to smell, mating behavior and defense against infectious disease than people do, which says something about the environment the mouse faces, scientists said.
Other creatures common in the lab have had their DNA mapped in recent years - most notably the fruit fly and roundworm - but the mouse is the only other mammal. That makes it all the more exciting to scientists, who hope to use the mouse map as a biological Rosetta stone to better understand the function of human genes.
"The mouse is a mirror in which we can see the human," noted Eric Lander, director of the Whitehead Institute Center for Genomic Research in Cambridge, Mass. Without the mouse, "we've been missing much of the story."
Already comparisons between the man and mouse are paying off. The mouse map has helped researchers discover mistakes in the human map and pinpoint human and mouse genes more accurately. Researchers have already discovered 1,200 new human genes and 9,000 new mouse genes thanks to the map.
The mouse should be just the beginning of a flood of animal DNA. A genetic map of the rat, which also holds a favored place in the lab, is well under way. Other creatures whose DNA is in line for decoding include the chimpanzee, chicken, cow, dog, sea urchin and honeybee.
Scientists who have tapped into the mouse database are also finding that it's cutting the time needed to conduct certain genetic experiments from years to weeks -"freeing the minds of a lot of graduate students to work on important biomedical questions," said Lander.
But enough mysteries remain to occupy researchers for years to come, said Lander. (Why do only mice have tails, for example, if we both have the gene?) "It's just the opening of what I think will be an exciting decade," he said.