Genes-R-Us — DNA gone to the dogs
Posted: Wednesday, November 30, 2011 5:01 pm
Dogs are on my brain. On Thanksgiving weekend, two homeless dogs were undoubtedly drawn to the smell of food, the welcoming invitation of our porch light and the merry sounds of our small army of kids and grandkids (10 in all) playing football in the yard.
Somehow Ebony and Ivory identified our household as a prime target for fostering or outright adoption. So this week’s column will extrapolate what we have learned about human DNA to woman’s best friend.
You may wonder, “What kind of dogs are they?” Ebony resembles a lab and looks to be about one and a half years old. She is all black except for a small white bib and dappled booties. Ivory resembles a German Shepherd and is entirely the color of scrumptious white chocolate. Nowadays, with doggie-DNA testing, it is possible to disentangle the mix of breeds for Ebony and Ivory.
For doggie-DNA testing, one swabs the inside of the dog’s cheek and then sends the sample away for the popular Canine Heritage™ XL Breed Test. The test costs about $50 and uses 48,000 SNPs.
SNPs are those single DNA “letters” or bases that vary between canine species. The test will specify (a) primary breed should there be one. (b) secondary breed and (c) “in the mix” breeds from 120 species.
The Heritage™ XL Breed Test is analogous to the DNA test that 23andme.com uses for you and me. That test is based on 1.5 million SNPs, that vary among humans.
In the 23andme test, you will not find out that you are a one-half Rottweiler and one-half Toy Poodle. Rather you will find out where your mother’s mother’s mother’s … mother and your father’s father’s father’s … father came from thousands of years ago and all sorts of information regarding your genetic disease risks and traits.
With the arrival of Ebony and Ivory, I began reading about the genetic and environmental evolution of dogs. Prior to cheap genomic analysis, the experts thought dogs originated in China. Wrong. Now. based on a more comprehensive DNA testing platform (i.e. more SNPs) and more advanced mathematical analysis methods, domestic dogs appear to have come from Middle Eastern gray wolves. This is the exact same location from which domesticated cats, much of our livestock and farming also originated.
Eighty percent of dog breeds were created in the last 200 years, according to a seminal paper published in 2010 by UCLA scientists. The other 20 percent are ancient breeds. Three distinct and large groups, comprised of herding dogs, sight hounds and scent hounds, have a very strong genetic signature that conforms to worldwide definitions of the three breeds.
The UCLA research group found that the genetic basis (or genotype) for a given dog breed (or phenotype) is often simply a difference in a single gene. For example all short-legged dogs, like a dachshund, turn out to have an extra copy of one gene called “fibroblast growth factor 4” or FGF4. The overall small size in a dog, such as in my Bichon Frise, is due to a mutation (i.e., a different DNA spelling) in a single gene called “insulin growth factor” or IGF.
Humans, by contrast, typically have many genes involved in a trait like height.
In a study spanning several decades, gray wolves were selectively bred for gentle temperaments. By nine or 10 generations, a different phenotype occurred. The coat coloration went from essentially one color to a spotted coloration. Here selective breeding for one trait, temperament, triggered an interesting secondary trait that could also be selectively bred upon.
Regardless of the genetic mix, the Pudge-N-Pals Humane Society of Union City is dedicated to caring for dogs (and cats!) that are in need of a forever home. If you are willing to be a foster parent or looking for a pet to love, Pudge-n-Pals can set you up. Alternatively, consider donating to this 501(c) 3 organization to help fund much-needed medical care or food for these animals.
Contact Laura Archer at 335-3502, if you are interested.
Wait, I just got a call from my husband. He is leaving work early to bring home a dog house. What can this mean? Are Ebony and Ivory soon to become man’s best friend, too? I surely hope so!
Editor’s note: Nancy Miller Latimer has worked in scientific research and development for 27 years. She blogs at neuronalbeauty.blogspot.com. Published in The Messenger 11.30.11