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Transgenic Animal Stories
by author Elisabeth Abergel, PhD

Transgenesis refers to the splicing of genes from different species that generally would not mate in nature. Generally, transgenesis involves the introduction of functional genetic material into the germline (or reproductive cells) of organisms. The techniques used to create transgenic cells either inactivate existing genes or introduce new genes to be activated.

Animal transgenesis was first performed approximately two decades ago, when the first oversized transgenic mice were produced. Following mouse transgenesis, early experiments with pigs engineered with human growth hormone (known as the Beltsville pigs) reduced the fat content of their meat but had devastating physiological consequences. The animals suffered from severe health problems caused by uncontrollable growth and had to be destroyed. Far from being an exact science, animal transgenesis raises fundamental ethical and animal welfare questions.

Why produce transgenic animals? There are three major applications:

• in the pharmaceutical industry: for basic research, experimental and disease models; as a source of organ transplantation; as bioreactors for the production of therapeutic or other proteins; for vaccine and toxicological testing
• in agriculture: for meat and dairy production; wool production; aquaculture; disease resistance; physiological manipulations
• in industrial applications: as bioreactors for the production of industrial proteins (such as fibres) and for creating “environmentally friendly” industrial animals.

There are several Canadian examples of animal transgenesis. Montreal-based Nexia Biotechnologies Inc. uses goats to produce spider silk proteins. The animals were “engineered” with spider silk genes integrated in their mammary gland cells so that they can be milked for BIOSTEEL, a thread so strong that it can be used for ultra-light military armour or suture thread.

As another example of bioreactor animals, the semen of boars contains foreign proteins that can be used as pharmaceuticals. TGN Biotech, a Canadian company, has produced three lines of hogs able to synthesize proteins, hormones or growth factors in their seminal fluids.
The Enviropig, created at Guelph University, has been engineered to digest inorganic phosphates from its feed by adding a gene that causes the saliva to contain a certain microbial enzyme. Less toxic farm manure from fecal waste can then be produced. The Enviropig is hailed as a Canadian success story.

The transgenic Atlantic salmon, called AquAdvantage, was engineered to grow 400 per cent faster than wild salmon and grew six times the normal size by the end of one year. A product of Aqua Bounty Farms located in PEI, AquAdvantage salmon could soon be the first transgenic animal to be approved for food. The US Food and Drug Administration (FDA) has been evaluating the request filed last year by the company for the approval of its “products.”

The FDA has chosen to assess the transgenic fish not as a food but as a drug due to the inserted gene’s ability to speed up growth. Although the people behind AquAdvantage claim that their fish are 96 per cent infertile, many fear that serious ecological risks could ensue from those transgenic fish that are capable of mating with wild salmon stocks–especially given that escapes from fish farms are very common. This summer it was reported that tens of thousands of Atlantic salmon had escaped from BC fish farms into more than 77 of the province’s waterways.

Regulations covering the environmental and health safety approval of transgenic animals have not yet been finalized. These are expected sometime soon, with Enviropig and AquAdvantage salmon likely to become the first two Canadian products sold as food. At the moment, transgenic animals fall under the New Substance Notification Regulations of the Canadian Environmental Protection Act, which is administered by the New Substances Division of Environment Canada ec.gc.ca/substances/.

Even if transgenic salmon and pigs were to get food safety approval from Health Canada and the Canadian Food Inspection Agency (inspection.gc.ca/english/ppc/biotech/tech/animae.shtml), consumers may not be enthusiastic about eating meat from transgenic animals. Considering all the unanswered and unasked ethical questions about the risks posed by such technologies–to animals, humans and the environment–the use and production of transgenic animals should be of concern to everyone.

Elisabeth Abergel is a food and biotechnology analyst with a PhD in environmental studies.

Source: alive #231, January 2002