![]() In addition to all these dogs, the study also examined the genomes of 13 species of wild canids from around the globe and 35 ancient dogs and wolves. ![]() A full 1,156 of those genomes came from modern dogs ( Canis familiaris), a single species which encompasses 230 established breeds, 140 indigenous and village dogs, and one dingo (which is generally considered to be a type of dog but that some argue is its own wild species). The researchers then searched for the backwards variants of the IGF-1 gene across a staggering 1,431 canid genomes. Because dogs get one set of 39 chromosomes from each parent, they can end up with two copies of the same variant or one of each. ![]() The team found that there were two versions or variants of the gene that codes for this strand of RNA present in domestic dogs, one of which appears to interfere with the production of the growth-regulating IGF-1 protein. This genetic sleuthing hit on a particular gene that gets trasncribed into what's called long non-coding RNA, which is so named because it doesn’t code for any proteins. ![]() More than a decade later and with the help of modern genomic analysis, a post-doc in Ostrander’s lab named Jocelyn Plassais used the first Covid-19 lockdown in the summer of 2020 to take a fresh look at the IGF-1 gene region in dogs with an unorthodox approach: he started reading some of the genetic code backwards. By contrast, there are roughly 10,000 DNA markers in humans that all play roles in determining how tall a person becomes, with the most influential single gene accounting for less than half a percent.īut until now researchers could never locate the mutation, or the alteration in the gene’s DNA sequence, at the IGF-1 gene region that led to less of the growth-promoting protein in smaller dogs. On balance, the gene that codes for the IGF-1 protein controls about 15 percent of size variation among dogs while 19 other genes account for the rest. For instance, a toy poodle has much less IGF-1 protein floating around in its blood than a larger standard poodle does. The IGF-1 protein is a big deal when it comes to body size in mammals and dog breeds are an especially clear example. The gene in question codes for a protein called insulin-like growth factor-1 (IGF-1). Now, research published today in Current Biology suggests instead that the genetic fodder for the tiny dog breeds of today was actually lurking in the DNA of ancient wolves that lived more than 50,000 years ago, long before domestication began.īack in 2007, Elaine Ostrander, a geneticist at the National Human Genome Research Institute and senior author of the current paper, and her colleagues discovered that a single gene is largely responsible for the size differences between dog breeds. Given the huge size difference between wolves and the littlest dogs, it’s easy to assume the genetic changes that brought about the supreme smallness of Chihuahuas and their ilk only appeared as humans started domesticating dogs, about 15,000 years ago. Looking at a snorting French bulldog or a prancing Pomeranian it can be hard to grasp how these pint-sized pooches could have possibly descended from wolves, which today routinely exceed 100 pounds and can take down bison.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |