I have a new web gallery up at Discover on the genomics of your Thanksgiving dinner. It discusses what scientists have learned from sequencing many of the foods we’ll eat this week, including turkey, potatoes, apples, and more.
One of the most interesting things I learned in the course of my research is that turkeys may turn out to be a great research model for cancer. It turns out that as humans domesticated turkeys, selecting birds for faster growth and bigger breasts, for instance, we also concentrated a genetic mutation that makes the birds particularly susceptible to carcinogens in the environment. In particular, domestic turkeys have a mutation that makes them extraordinarily vulnerable to aflatoxin, a substance produced by a variety of species of the fungus Aspergillus. The toxin is most often found in nuts and seeds–turkeys and other birds may be regularly exposed to the toxins through their diets.
Domesticated turkeys, it turns out, are particularly vulnerable, due to a mutation that affects how the birds metabolize the aflatoxins. Roger Coulombe, a toxicologist at Utah State University, who was involved in the sequencing of the turkey genome, told me that when it comes to cancer, the domesticated turkey is “probably the most susceptible animal known to science.” He and his colleagues were able to determine that the mutation in question occurred in the late 1800s. (Wild turkeys and heirloom turkeys, birds that resemble the earliest domesticated turkeys, do not have the mutation in question.)
Now that the genome has been sequenced, Coulombe and his colleagues hope to get more information about how the cancer vulnerability mutation works and is regulated. It could, he hopes, have implications for human medicine. And the turkey, it seems, could become the next cancer lab mouse.
Rawal, S., J. Kim and R.A. Coulombe, Jr. (2010). Aflatoxins in Poultry: Toxicology, Metabolism and Prevention. Research in Veterinary Science 89:325-331. PMID: 20462619.
Rawal, S., Reed, K.M., Mendoza, K.M. and R. A. Coulombe, Jr. (2009). Structure, genetic mapping, and function of the Cytochrome P450 3A37 gene in the turkey (Meleagris gallopavo). Cytogenetics and Genome Research 125: 67-73. PMID: 19617698.
Guarisco, J.A., Hall, J.O., and R.A. Coulombe, Jr. (2008) Butylated Hydroxytoluene Chemoprevention of Aflatoxicosis in Turkeys: Effects On Aflatoxin B1 Bioavailability, Hepatic DNA Adduct Formation, and Biliary Excretion In Vivo. Food and Chemical Toxicology 46: 3727-3731. DOI: 10.1016/j.fct.2008.09.050.
Guarisco, J.A., Hall, J.O., and R.A. Coulombe, Jr. (2008) Mechanisms of butylated hydroxytoluene chemoprevention of aflatoxicosis – inhibition of aflatoxin B1 metabolism. Toxicology and Applied Pharmacology 227: 339-346. DOI: 10.1016/j.taap.2007.11.017.
Yip, S.S.M. and R.A. Coulombe, Jr. (2006) Molecular cloning and expression of a novel cytochrome P450 from turkey liver with aflatoxin B1 metabolizing activity. Chemical Research in Toxicology 19:30-37. PMID: 16411653.
Image: Wikimedia/Agricultural Research Service