April 06, 2007

cool biology

Chihuahuas have it, Newfies don't

Scientists have just discovered which gene fragment controls the size of dogs, the mammal with the greatest range in size: no other species produces adults with 100-fold differences, like that between a 2-pound Chihuahua and a 200-pound Newfoundland.

In a study to be published today in the journal Science, researchers analyzed 3,241 purebreds from 143 breeds. Genetically, the yapper arguing with your ankle is almost identical to the drooling behemoth bred to hunt bears, except for a tiny bit of DNA — universally present in small breeds and largely absent in big ones — that suppresses the “insulin-like growth factor 1” gene. [...]

The study’s lead author, Elaine A. Ostrander, chief of cancer genetics at the National Human Genome Research Institute, said she had visited a lot of dog shows, asking for blood. [...] Making it “cool biology,” she said, is that the same gene suppressor is found in both mice and men, creating mini-mice and suspected in human dwarfism. And because it controls growth gone awry, Dr. Ostrander said, it will help cancer research, and is to be manipulated in mice. But carefully. A mouse the size of a Great Dane, she said, “would be a little scary, wouldn’t it?”

I guess I have a dog that doesn't know that she doesn't have the big dog gene. She thinks she's a big lab and regards small dogs with contempt. Not sure how she'd respond to a giant mouse.

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