Gene that gives dogs black fur

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 scientists from the Stanford University School of Medicine reports.

The study, reported in the Nov. 2 issue of Science, answers a longtime mystery: What determines coat color in dogs" While scientists 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...