Va. Tech to help decode the turkey's genetic gobbledygook
Thursday, November 26, 2009
If ever there were a candidate for genetic engineering, surely it is the pale, flavor-challenged bird that will adorn millions of American dinner tables Thursday as a matter of Thanksgiving ritual.
And here is a reason to give thanks: The day of the super-turkey might be nigh.
Virginia Tech scientists announced this week that they have secured funding to complete the genetic map of Meleagris gallopavo, the domesticated turkey. The U.S. Department of Agriculture has awarded a two-year, $908,000 grant to Tech and the University of Minnesota to finish decoding the turkey, one of a few species to be mapped at the genetic level. Turkeys are the fourth-leading source of meat on dinner tables. Cows, chickens and pigs have been genetically catalogued.
The possibilities for genetic manipulation seem endless. At a minimum, the turkey might be genetically engineered to convey a bit more flavor. And turkeys aren't the most comely of birds. Could they be bred for better looks as well as taste? How about a turkey that arrives pre-stuffed or packed with extra endorphins to pacify a dysfunctional family? Or thighs thick enough for the NFL?
"For me, it would be gigantic Earl Campbell legs," said Damian Salvatore, chef and owner of Persimmon Restaurant in Bethesda, alluding to the former football great. "If they could get some of that leg taste into the breast, that would be perfection to me."
University scientists say genetic mapping will help turkeys lead healthier lives. Breeders will come to know how the turkey immune system works and how to fight off such pathogens as bird flu.
"The turkey, we hope, will live happier," said Rami Dalloul, assistant professor of poultry immunology in the Department of Animal and Poultry Sciences at Tech.
But this is not all about the interests of the turkey. One goal of genetic mapping is to identify genes that might produce larger breasts or plumper legs -- potential breakthroughs for the diner and the Renaissance Fair vendor, to be sure, but without much payoff for the bird.
"The traits you might want to improve are sometimes complex and not defined by a single gene," said Otto Folkerts, associate director of technology development at the Virginia Bioinformatics Institute at Tech. "Sometimes people might want a turkey to taste more like a wild turkey. You can start addressing flavor traits, texture traits."
A group called the Turkey Genome Sequencing Consortium, including researchers from the University of Maryland and the USDA as well as Tech and Minnesota, picked up the genetic drumstick a year ago. Their work follows on the heels of the Human Genome Project, a decade-long quest, completed in 2003, to map the more than 20,000 genes that define Homo sapiens. The chicken genome was mapped by 2005.
Turkeys are more akin to chickens, genetically speaking, than humans, although there is speculation that turkeys and humans share a common ancestor perhaps 200 million years distant. Turkey DNA contains 40 pairs of chromosomes, compared with 23 pairs in the human code. Human DNA contains about 3 billion chemical building blocks, called base pairs, and the turkey genome holds about 1 billion.
About nine-tenths of the turkey genome has been mapped. Dalloul described the process: Researchers break up a DNA sample, culled from turkey blood, into "very small pieces," then place the pieces in order and put those sequences together to create the full genome. If one thinks of the genome as a book, the 40 chromosome pairs would be chapters, the thousands of genes would be pages and the billion individual base pairs would be letters.
The challenge is that the genetic book is assembled at random. Some letters are missing, and remain missing -- like hard-to-find baseball cards -- even after scientists have mapped the entire genome six times.
"Every time, you will find pieces that were not there before," Dalloul said. "It's actually harder now to find the remaining 10 percent, which is what this grant is about."
Scientists say it will take another year to complete the map, then another to find genetic variance from one breed of turkey to another. And it might be several more Thanksgivings before genomic science reaches the dinner table.