Starting with an initial cohort of 15 obese and 18 lean Labrador retrievers, Raffan and her colleagues selected three obesity-related genes to examine, all of which were known to affect weight in humans. This first analysis turned up a variation in a gene called POMC. In more of the obese dogs, a section of DNA was scrambled at the end of the gene. The deletion is predicted to hinder a dog's ability to produce the neuropeptides β-MSH and β-Endorphin, which are usually involved in switching off hunger after a meal.
POMC isn't the only gene contributing to canine obesity. Others are still waiting to be discovered.
In a larger sample of 310 Labrador retrievers, Raffan and her colleagues discovered a host of canine behaviors associated with the POMC deletion. Not all Labs with the DNA variation were obese (and some were obese without having the mutation), but in general the deletion was associated with greater weight and, according to an owner survey, affected dogs were more food-motivated--they begged their owners for food more frequently, paid more attention at mealtimes, and scavenged for scraps more often. On average, the POMC deletion was associated with a 2 kg weight increase.
Use of food to train assistance dogs selects for assistance dogs that are perpetually hungry. Seems like a problem.
Notably, the POMC deletion was markedly more common in the 81 assistance Labrador retrievers included in the study, occurring in 76 percent of these dogs. "We had no initial reason to believe that the assistance dogs would be a different cohort," says Raffan. "It was surprising. It's possible that these dogs are more food-motivated and therefore more likely to be selected for assistance-dog breeding programs, which historically train using food rewards."
Once all the obesity-boosting genetic variants become known and genetic editing technology matures some people will do genetic engineering to produce puppies without these genes. I also expect lots of genetic load (purely harmful) mutations to be weeded out. A dog 30 years from now will be vastly genetically superior to a dog today.
I am concerned about genetic improvements to cats more than to dogs. Humans have moved cats all over the world and this has made cats into predators in numerous areas where they did not use to exist. Domestic cats much more heavily breed with wild cats. So genetic improvements to domestic cats will leak out into wild cats, making them far more capable of killing birds and other wildlife globally.
|Share |||Randall Parker, 2016 May 07 10:38 AM|