Evolutionary Origin and History of Antifreeze Glycoprotein Gene in the Northern Cod Fishes (Gadidae): Creating Sense from Non-Sense DNA?

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The evolutionary adaptation to polar climates can provide a model for adaptations to climate changes in general. Today's frigid polar waters are inhospitable for most bony fishes, but some can live in freezing waters because they have evolved antifreeze proteins. The antifreeze glycoproteins (AFGP) of northern/Arctic cod fishes bind to invading ice crystals, preventing the fish from freezing. Novel proteins are commonly thought to evolve from a pre-existing protein gene rather than from other kinds of DNA. The evolution of the cod AFGP gene may defy this long-held paradigm. The codfish genes analyzed thus far suggest that the repetitive DNA encoding the AFGP arose from repeatedly copying a snippet of ancestral, non-protein coding DNA. Furthermore the AFGP trait appears in two cold-water codfish groups that are distant cousins, suggesting the AFGP gene evolved twice, in separate branches of this family tree. To test these two intertwined evolutionary hypotheses, the distribution of the AFGP trait will be mapped onto the codfish family tree. Then the AFGP genomic regions will be compared for two distant species bearing complete AFGP function, and with the corresponding region in a related species without AFGP function. If the antifreeze gene did not evolve from coding DNA, the result would indicate that evolutionary novelty has more sources than previously thought. The principal investigator will train graduate and undergraduate students in cutting edge genomics technology and science. The sequence data from the project will also be utilized in a "Find a Gene" workshop for a group of high school students for basic training in bioinformatics and genome data management.