They discovered two variants of the ventral promoter. On the other hand, dogs have an additional hair cycle-specific promoter that mediates the production of agouti signaling protein during specific stages of hair growth and enables the formation of banded hair.įor the first time, the researchers characterized these two promoters in detail, in hundreds of dogs. Dogs, on the one hand, have a ventral promoter, which is responsible for the production of agouti signaling protein at the belly. The gene for agouti signaling protein has several initiation sites for reading the genetic information, which are called promoters. "We realized early on that the causative genetic variants have to be regulatory variants which modulate the rate of protein production and lead to higher or lower amounts of agouti signal protein," Tosso Leeb explains.įive instead of four distinct coat color patterns If no agouti signaling protein is present, black eumelanin will be formed. If the agouti signaling protein is present, the pigment producing cells will synthesize yellow pheomelanin. However, commercial genetic testing of these variants in many thousands of dogs yielded conflicting results, indicating that the existing knowledge on the inheritance of coat color patterns was incomplete and not entirely correct.ĭuring the formation of coat color, the so-called agouti signaling protein represents the body's main switch for the production of yellow pheomelanin. Prior to the study, four different patterns had been recognized in dogs and several genetic variants had been theorized which cause these patterns. A precisely regulated production of these two pigments at the right time and at the right place on the body gives rise to very different coat color patterns. Wolves and dogs can make two different types of pigment, the black one, called eumelanin and the yellow, pheomelanin. Two pigments and a "switch" for all coat colors The study has just been published in the scientific journal Nature Ecology and Evolution.
Not only did they clarify how the coat color patterns are genetically controlled, but the researchers also discovered that the light coat color in white arctic wolves and many modern dogs is due to a genetic variant originating in a species that went extinct a long time ago.
Researchers including Tosso Leeb from the Institute of Genetics of the University of Bern have now finally been able to solve the puzzle. The inheritance of several coat color patterns in dogs has been controversially debated for decades.
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