Image: Scott Bauer, ARS.USDA
Piglets Inherit Genetic Modification
Canada has approved limited production of animals dubbed "enviropigs™," a genetically modified breed of pigs producing up to 65% less phosphorous in pig poo and urine. The pigs pass the genetic modification along to their young, as well.
The very idea that a genetically modified animal rates the moniker "enviro-" points to the severity of the issue addressed by the science behind these pigs. Phosphorous is a fertilizer. Phosphorous in animal and human wastes runs off or discharges to surface waters, where it spurs large algal blooms. The algae use up the oxygen in the water, leaving behind a "dead zone," an area of lake, river, or ocean where nothing can live due to the hypoxic conditions.
How does the enviropig work (image in extended)? And does the dead zone problem justify permitting production of these "franken-pigs"?
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The genetic modification used by scientists at the University of Guelph, Ontario involves an enzyme known as phytase. Phosphorous plays an essential role in the growth of bones, construction of DNA and RNA, and in regulating cell and organ processes. But most of the phosphorous in a grain-based diet are bound up as organic complexes which pigs cannot digest. Supplementing pig diets with phytase, itself produced from genetically modified fungi Aspergillus Niger, has been advocated as an environmental protection measure.
Image: Enviropig™, University of Guelph, Ontario
Scientists spent over a decade searching for the genetic secret to digestion of organic phosphorous. They found the genes in the DNA of Escherichia Coli bacteria. In order to ensure the segment of DNA could function in mammals, scientists paired the E. coli DNA with a DNA promotor from mice. The promotor takes care that the bacterial DNA is transcribed. In fact, early tests showed that the genetic modification not only enables pigs to produce phytase in their saliva, but the ability is inherited. Pigs in the eighth generation still have the gene, which has been transmitted unaltered to successive piglets.
Unlike some genetically modified strains, which are engineered or contractually designed so that farmers much purchase expensive new stocks every season, enviropiglets inherit the genetic advantage. Additionally, the cost of raising pigs is reduced because farmers do not need to supplement pig diets with phosphorous nor with commercially manufactured phytase. Waste treatment costs, to manage the phosphorous in manure, can also be saved.
Canada has approved only limited production of the Enviropigs, in controlled research environments. It will be years before meat from genetically engineered pigs could be available for human consumption. "This will be probably the most significant transgenic food to be approved. We're in new territory," Steven Liss, a spokesperson for the project, told National Geographic.
Are genetically modified pigs another "franken-food" risk that we need to fear? Certainly, management of the unintended consequences is an essential part of such science. Because phosphorous is a natural and essential mineral, the potential risks are less scary than some projected genes-run-amok scenarios. And given that phytase supplements rely today on genetic engineering, this step is a matter of scale, rather than principle. In the face of the potential damage dead zones cause in our eco-systems, no solution can be discarded without investigation.
More on Pigs and Dead Zones:
8 Worst Man-made Environmental Disasters of All Time
Dead Pigs: Scientists' Latest Tool in Understanding Ocean Dead Zones
America's 10 Most Endangered Rivers Of 2009
Watergoat Stormwater Debris Boom Eats Trash Out of Storm Drains