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Playing god with genetic tinkering

Alan Braunholtz

Science not only leapfrogs our slowly evolving genetic behavior but also the faster evolving ethics, morals and rules of our societies.

Stem cells and genetically modified organisms are two cases in which we’re trying to play catch-up and are embroiled in contentious debates about what is the right thing to do with this new knowledge.

GM food is an interesting debate to watch with pro-GM industry casting themselves as the altruistic food saviors of the world and the anti-GM brigade running around shrieking about “frankenfoods, genie out of the bottle, Pandora’s box,” etc. Neither side is being particularly honest and each GM application needs to be assessed on its own merits. So far, I’ve yet to read of any trial that demonstrated health risks or of any application of GM crops that is an obvious “must have” for the world.

The money spent on developing the famous golden rice, which is heralded as saving x million from malnutrition, would have been better spent convincing people to grow/eat brown rice (which already has the nutrients) instead of white rice.

The GM food debate should be about whom we want controlling/owning the seeds of the crops the world eats. Is it OK for a few giant agribusiness companies to effectively own the world’s seed banks or would it be better for most varieties to be freely available in the global public domain to anyone who wants to grow, sell or use them? Third World farmers find it hard to understand how a company can take a crop that mankind’s developed over thousands of years, tweak and improve it and then say this seed variety belongs exclusively to us. What about the previous thousand years of development they’re piggy backing on – “who is paying my ancestors for that?” It’s a complex issue with many companies using economic muscle and aggressive application of U.S. patent law to lay claim to things that belong to all mankind.

Another branch of genetic modification that needs some international debate is the development of GM diseases and pests aimed at controlling pests. In Australia they’ve produced a cytomegalovirus that sterilizes female house mice. In New Zealand, work progresses on modifying a parasitic nematode to sterilize brushtailed possums. Australia also aims to modify myxoma virus to sterilize rabbits, while conversely Spain is trying to produce a myxoma virus to act as a vaccine to protect Spanish bunnies from myxomotosis and calcevirus. And there’s the problem.

One country’s pest is another’s essential block of the food chain. Spain is so short of rabbits that rare predators such as the Iberian lynx and the imperial eagle are threatened, and hunters have nothing to shoot. While a pest in New Zealand, the brushtailed possum is protected in Australia. How do you prevent your GM anti-pest virus/disease from devastating wildlife in other countries? Another concern is how will the GM disease behave? It may happily stay in its intended pest or it could mutate, recombine and jump species to infect in Pentagon speak “non-legitimate target animals” or in a frankenfood scare moment, people.

Not surprising,y the scientists directly involved think it’ll be fine. “Australia’s an island, there are quarantine procedures,” etc. Others look at the checkered history of biological control and want to address some safety issues first. Once these diseases are let go, they can’t be put back. We don’t want to be picking up the pieces of someone’s hastily dropped “can’t miss” solution. Suggested safety measures are linking the GM disease to a chemical that is only present in the diet of animals in the target are or an antidote could be developed to protect animals that are behaving properly in their original countries. At the moment there is almost no communication, let alone agreements or regulation, among countries playing with this research and others that may be affected.

With the arrival of West Nile virus on the backs of mosquitoes, another potential genetic development needs discussion. Geneticists are mucking around with mosquito genes, trying to prevent the spread of malaria. They’re focusing on making the mosquito less likely to transfer malaria. Soon they’ll be able to release mosquitoes that are unable to pass malaria on to humans.

This sounds good, except anti-malarial genes don’t make the mosquito genetically fitter than wild ones. If they did, natural selection would have eradicated malaria all by itself. Research shows the anti-malarial genes are a hindrance to the mosquito and will get selected against. Trying to couple this gene to a truly advantageous piece of DNA should help. When the advantageous piece of DNA is selected, the anti-malarial DNA comes along as baggage. Eventually though, mutations will uncouple the two, and when it does the anti-malarial gene will die out. Driving the anti-malarial gene into the wild populations looks difficult.

Enter the mosquito extinction program. Austin Burt of Imperial College, London, came up with the idea to use parasitic genes known as HEGs to potentially eliminate these parasitic insects. “Homing Endonuclease Genes” possess the ability to get themselves copied onto both sets of chromosomes in a cell. As all sperm and eggs will have a copy of an HEG gene and consequently all offspring, they don’t follow the normal laws of heredity. Normal HEGs are good parasites, doing little harm to their host, a good tactic to avoid being selected against. Austin Burt thinks that if you change this and insert the HEG into the middle of a gene (destroying its function), essential for, say, larval development, you stand a good chance of destroying the species.

As every offspring of an HEG mosquito will have the gene, it will spread very rapidly. If two HEG parents breed, their offspring won’t develop. It’s pretty much a race between the spread of HEG and the start of natural selection for mosquitoes with no HEG. Burt calculates that the rapid spread will swamp natural selection’s ability to pick non HEG or mosquitoes resistant to the effects of HEG. These require time and the hereditary behavior of HEGs doesn’t allow much.

At the moment, the technology isn’t there. But if it were, should we do it? We’ve wiped out lots of species, but mostly by accident or through selfish short sightedness. Some may argue we intentionally wiped out predators like the wolf and grizzly and the plains buffalo not only to make money but also to starve out the plains tribes who were being annoyingly persistent.

Times have changed, and now it’s an ethical question. Should we be trying to wipe out species? Later generations may want them around. Should we be playing God?

Who knows, maybe all mosquitoes do have some vital unknown role in the ecosystem. Unlikely, but other insects and birds may depend on them.

Still, except for a few strains guarded in weapons labs, we eradicated small pox and that’s accepted as a good thing. No one is walking around with “save the smallpox” placards. Maybe that’s the future for mosquitoes.

Alan Braunholtz of Vail writes a weekly column for the Daily.


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