Alter Genes, Risk an Ecosystem?
The Washington Post
As the jaguar hunts at dusk in the jungle, the spots it has developed over the millennia help camouflage it from its prey. When a baby crocodile is born, it immediately knows to lunge out of the water for insects but will avoid dead ones on the water surface or sinking to the river floor. Darwinian survival of the fittest has long explained these kinds of adaptations. But the advent of genetic engineering has prompted scientists to analyze further the links between the genetic structure of life-forms and the environments in which they live. In addition to the environment spurring genetic changes in jaguars, crocodiles and other living things, do the genes of animals, plants and insects affect the world that surrounds them in more complicated ways?
This theoretical question has particular urgency because of the ongoing and increasingly heated international debate over agricultural biotechnology. The process by which the modified genes of plants (or fish or insects) might affect the environment is suddenly a hot topic, and researchers on all sides are weighing in.
That the human genome project has found far fewer genes than initially expected has added to the debate by making it clear that genes by themselves may not have the enormous diversity needed to account for the full range of human traits and behaviors. Rather, genes must interact with the environment, and among themselves, to produce the traits that distinguish a person from a chimpanzee or an earthworm, or one person from another. The genome of an organism is a complex and dynamic environment unto itself. Any analysis of how genetically altered organisms will affect the environment must take into account all the ways in which the traditional "outside" environment interacts with the newly recognized and equally complex "internal" genetic environment, some scientists suggest. In an essay that is being embraced as an important philosophical advance by some environmentalists, Arjun Makhijani of the Institute for Energy and Environmental Research in Takoma Park has put some of these ideas together into a broadside against genetic engineering. He argues that the relationship between the genetic material of living things and the ecosystems in which they live is deep and changeable, and that tinkering with genes may upset the environment -- and plants and animals in that environment -- in far more complicated and far-reaching ways than have been considered.
"My hypothesis is that the genome is an internal expression of the ecosystem in which it lives," Makhijani said. "If individual genomic structures are so intimately connected with their ecosystems, then it makes sense that messing with genomes would have an effect on . . . the entire ecosystem." He concludes that products such as corn genetically engineered to repel insects -- a process that involves the addition to the corn seed of a gene from bacteria that naturally perform that task -- are inherently more risky to the surrounding ecosystems than conventional corn. Genetic engineering, he argues, will have much broader effects than have generally been appreciated because it involves the combination of genes from disparate organisms such as bacteria and corn that would not normally share their genomes.
While some of the changes may be benign, Makhijani points to recent Australian efforts to genetically engineer a mousepox virus to control rodents and crop damage as an example of the dangers. The goal was to increase the immune response of the rodents so female mice would reject their own eggs as foreign objects. Unexpectedly, however, the opposite happened, and the genetically engineered virus suppressed the immune system in lab mice. The experiment created a new kind of supervirus that, if it had been introduced into the environment, could have set off a cascade of potentially devastating changes.
Richard Strohman, an emeritus biology professor at the University of California at Berkeley, has explored similar ideas and believes that the general environmental risks of biotech crops have not been fully examined. "There's been so much focus on how one gene might cause one particular trait," said Strohman, who serves on a panel at the University of Pennsylvania Center on Bioethics examining ethical issues of genetically engineered crops. "But there's no real discussion of the more complex issue of how genes are changed by natural selection in the environment and how that might be affected by genetic engineering." In a report last year that was generally supportive of genetic engineering of plant crops, the National Academy of Sciences' National Research Council also highlighted the need for more research into these long-term ecological effects.
Human agriculture has, of course, modified plants for centuries and caused vast changes in the environment. Virtually none of the crops grown in the United States are native, and all have been crossbred to a great degree. In a recent article in the journal Plant Physiology, Channapatna S. Prakash of the Center for Plant Biotechnology Research at Tuskegee University wrote that while "gene flow" from crops such as engineered corn is a legitimate concern, the potential environmental harm is minuscule when compared with the fact that corn -- a species not native to the United States -- is now grown here on 75 million acres. In addition, Prakash writes, modified corn includes one or two genetically engineered genes out of 50,000. "Plants produced through the crossbreeding of genetically engineered crops and their wild relatives are few and very unlikely to compete successfully," he said. "I don't see any empirical evidence that says gene flow from genetically engineered crops confers different risks than gene flow from conventional crops."
Fears about gene flow have been "orchestrated by people who don't like biotech or have a vested interest, like organic farmers," he said. Val Giddings of the Biotechnology Industry Organization said that today's movement of genes from one life-form to another is not problematic and that it is actually how all species alive today came to be what they are. Biotechnology allows the process of change -- the introduction of mutations into existing species -- to be far more predictable and controlled than ever, he said.
Norman Ellstrand, a professor of genetics at the University of California at Riverside, has been studying the extent and dynamics of gene flow in crop plants such as radishes and sorghum. This unintentional crossbreeding with wild relatives is considerably more common than earlier believed, he has found, and has been associated with the evolution of more aggressive weeds for seven of the world's 13 most important crops. "Are [genetically engineered] crops likely to be different from traditionally improved crops?" he asks. "No, and this is not necessarily good news. It is clear that the probability of problems due to gene flow from any individual [plant] is extremely low, but when those problems are realized, they can be doozies."
In fact, Ellstrand wrote that he was aware of at least three
cases in which scientists decided not to engineer certain traits into
crops because of concern about what gene flow might do to nearby crops
and weeds. The possible environmental effects of agricultural biotechnology
have gotten most attention regarding monarch butterflies and corn engineered
to contain a protein from Bacillus thuringiensis (Bt) bacteria, which
naturally kill insects. A 1999 report in the journal Nature raised the
possibility that, based on lab tests, the larvae of monarch butterflies
could be harmed if pollen from Bt corn blew onto nearby milkweed plants
where they feed. That report caused scientific concern, but subsequent
research has generally minimized the actual damage that will be caused
to monarchs in and around the Midwest cornfields where larvae grow and