Stanford researchers sniff out gene that gives dogs...( STANFORD Calif. - A discovery about ...),Health

STANFORD, Calif. - A discovery about the genetics of coat color in dogs could help explain why humans come in different weights and vary in our abilities to cope with stress, a team led by researchers from the Stanford University School of Medicine reports.

The study, published in the Nov. 2 issue of Science, answers a longtime mystery: What determines coat color in dogs" While researchers have known since the 1900s that most mammals share the same genetic mechanism to determine coat color, by the 1950s they began to suspect that dogs were different.

Now after swabbing the inner cheeks of hundreds of dogs and analyzing the DNA in the resulting samples, a team led by genetics professor Greg Barsh, MD, PhD, has nailed the gene. To the researchers' surprise, the gene makes a protein that's part of a large and variable family called defensins, thought to fight infections.

What is clear now is that this protein engages the melanocortin pathway, a circuit of molecular interactions that controls the type of melanin and amount of cortisol produced by the body. Barsh's lab has studied this pathway, which determines skin and hair color as well as stress adaptation and weight regulation, for 15 years.

The discovery of a new participant in this pathway opens up new vistas for drug research, said the article's co-first author, Sophie Candille, PhD, a former graduate student in Barsh's lab. Candille visited five Bay Area dog shows over six months to gather hundreds of samples by gently swabbing the inside of the dogs' cheeks with a brush.

"It's painless for the dogs, so they didn't mind," she said. "The dogs we met at dog shows were very well-behaved and happy to cooperate." Candille also gathered samples from one of Barsh's dogs as well as dogs of her friends and neighbors. And she recruited dog breeders to gather samples and mail them in.

The project began a few years ago with boxers and Large Munsterlanders of differen
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