Field of genetic engineering in the last two decades has presented numerous possibilities for applications. The potential to create strange new dog breeds was not the first option considered. Rather, scientists hoped to utilize genetic modification to truly make a difference—not only for human beings, but also for the environment. A research team at University of Guelph took on this task. Say hello to Enviropigs: genetically modified pigs who now produce less phosphorous and, therefore, have fewer adverse effects on the environment.
Phosphorus is a nutrient that plays a variety of roles, both in technological applications and in natural processes. Every living thing requires a measure of phosphorus, in the form of phosphate, to survive because of its presence in the backbone of both DNA and RNA as well as for its role in transferring energy between cells. The problem with this particular nutrient begins when there is an excessive amount of it within an ecosystem, particularly in the case of water. Since phosphorus is needed for photosynthesis—the process by which plants convert the sun’s light into energy—a surplus can cause an explosion of algae growth. This huge algae population not only takes oxygen from other organisms in the water and blocks other plants’ access to light, but it can also make the water toxic to anything that may drink it.
According to a comprehensive assessment done by the Environmental Protection Agency in 2010, almost 20 percent of lakes in the United States have excessive concentrations of nitrogen and phosphorus, while for streams that percentage is even higher, at closer to 30 percent. This pollution affects drinking water for human and animal populations, and attempts to chemically treat the polluted water often result in other harmful effects. Phosphorus contamination in bodies of water hurts more than just the environment, as it hurts the country’s economy too. Unsurprisingly, the algae’s over-usage of oxygen harms the fish population of these lakes and streams, which damages the business of commercial fishing. The very visible nature of the algae’s unrestrained growth also negatively impacts the tourism rates in many communities, because it hinders recreational water activities and fishing for visitors.
A major cause of phosphorus pollution is fertilizer runoff. Pig manure is a main ingredient for many fertilizers, and because most pigs cannot digest phosphorus, it is present in large amounts. Pigs, though they need phosphorus as a nutrient, are unable to access the phosphorus in their regular food. Farmers then have to supplement their pigs’ diet with digestible phosphorus, like phytase or mineral phosphate. One way to reduce phosphorus runoff would be to reduce phosphorus concentrations in pig manure before it becomes fertilizer. In 1995, a research team at University of Guelph decided to see if these two problems could be solved with genetic modification. A section of mouse DNA was introduced into pig fetuses that would allow the pigs, like the mice, to produce phytase in their salivary glands. The presence of phytase would, if successfully introduced, enable the pigs to access the phosphorus in corn, soybeans, and barley and correspondingly lower the amount of phosphorus in their excrement. By 1999, the University had finally won the lottery with their thirty thriving transgenic pigs whose offspring also contained the mouse DNA. They could, in fact, digest between 50 to 75 percent of the phosphorus in their food through their modified saliva, which lowered the phosphorus content of their feces by about 60 percent. Aside from their genetically-introduced digestive ability, these Enviropigs were exactly the same as their Yorkshire pig brethren.
Comments