The Enviropig By Kylie Munro

What is the Enviropig?

The enviropig is a genetically engineered line of Yorkshire pigs that produces phytase in the salivary glands and secretes the enzyme in the saliva.

Why is this important?

Approximately 50 to 75% of the phosphorus in pig feed is present in an indigestible compound called phytate that passes through the digestive tract and is enriched in the manure. So when farmers use the manure as fertilizer, the chemical enters the watershed and causes algae blooms that deplete oxygen in the water and kill marine life.

The Enviropig excretes from 30 to 70.7% less phosphorus in their manure than regular pigs depending upon the age and diet — making them more environmentally friendly.

How it was Created

A transgene construct containing the mouse parotid secretory protein promoter gene sequence and the Escherichia coli phytase gene was introduced into the pig chromosome by pronuclear microinjection.

In other words: Scientists added an E. Coli bacteria and mouse DNA to a pig embryo.

How it Works

1) The promoter directs continuous production of the active phytase enzyme in secretory cells of the salivary glands

2) The phytase is secreted in the saliva and enters the mouth where it mixes with the feed consumed

3) The phytase is most active in the acidic environment of the stomach (pH range of 2.0 to 5.5 during food consumption). There the enzyme digests the phosphorus rich phytate molecules releasing phosphate molecules

4) The phosphate molecules are readily absorbed from the small intestine.

Drawbacks

Before the Enviropig can be commercialized, it's safety has to be tested. In the U.S., the Food and Drug Administration (FDA) is the main agency to determine whether it poses any risk to the public and the environment. The FDA has never dealt with transgenic animals.

Regulations for disposal of transgenic animals require that the carcasses be incinerated. Incineration has the drawbacks of cost, odor, and air pollution, and a proposed solution to is composting.

There has also not yet been any research to indicate that the transgenesis process causes any pain or discomfort for the affected animals.

Benefits

The one main benefit of the enviropig is that they contribute to an overall phosphorus pollution reduction.

By raising Enviropigs instead of ordinary pigs a more expensive manure phosphorus application limit could be avoided.

In addition it would to reduce the feed cost by eliminating the need to supplement the diet with either phosphate or phytase.

Social Implications

  • More expensive manure phosphorus application limit could be avoided.
  • Feed cost is reduced by eliminating the need to supplement the pigs diet with either phosphate or phytase.

Ethical Implications

  • The reason for the Enviropig is to reduce phosphorus pollution.
  • The manipulation of Yorkshire pigs serves a goal that would not benefit pigs directly, so perhaps it could be a violation of some animal rights.
  • But by doing this they can slow or even stop algae growth that kills marine life and save some species.

Legal Implications

  • First of all there are no laws against genetically modifying animals, but that doesn't mean that it is morally right.
  • It only tells us just how fast science and new technologies are moving and growing in our society and that todays laws are just not caught up to the pace that science is moving at.

Fun Facts!! Part one

1. A promoter turns on a gene at the right time and in the right place.

Scientists had to figure out how to insert the phytase gene into the pig and have it be expressed in the correct place (expressed in the tail would be useless since the phytate problem is in the digestive tract).

To get the gene expressed in the digestive tract, the scientists needed to find a promoter, to which the gene is connected. (The promoter that worked best was from the mouse)

Whoa!!! We learned about promoters in biology class!!

Fun Facts!! Part two

2. Humans have E. coli in their guts, and likely have phytase as well.

The gene that makes the phytase comes from E. coli. But this doesn’t mean the pork will contain E.coli, scientists are only using the gene – not the bacteria!

The End

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