Let's play God! Gene drives could be a powerful new tool to manage wild ecosystems.

• Author: Bailey, Ronald
• Position: Columns - Column

WOULDN'T IT BE great if scientists could genetically engineer mosquitoes to be immune to the malaria parasite, thus protecting people from that disease? How about restoring the effectiveness of a pesticide by eliminating resistance genes in weeds and insect pests? Or altering genomes to eradicate a pesky invasive species?

These are exactly the sorts of things that a new biotechnological tool could do--and that's got some people worried.

In a July article for eLIFE, a team of researchers led by the Harvard biotechnologist Kevin Esvelt outlines a system that uses the new CRISPR gene editing technique to alter the genomes of wild populations of plants and animals. CRISPR is based on bacterial genes and proteins that can identify and cut any desired segment of DNA in an organism's genome. Appropriately configured and guided, it can replace any gene with a newly engineered version. Esvelt and company want to use CRISPR to construct "gene drives" that can quickly spread beneficial engineered genes through sexually reproducing populations. A gene drive works by making sure that both copies of a targeted natural gene are replaced with the engineered version.

For example, researchers could take a gene drive specifying an anti-malarial protein and insert it into mosquitoes in the laboratory. They would then release the insects to breed with wild mosquitoes. Ordinarily, the progeny would get one copy of a gene from each parent, but in this case, the gene drive would excise and replace the natural copy from the wild parent with the anti-malarial version, thus guaranteeing that it would get passed along when the next generation of mosquitoes breeds. Eventually, essentially all of the mosquitoes in the targeted species would carry the engineered version.

Another proposal would get rid of invasive species by creating a suppression gene drive that biases the production of sperm containing Y chromosomes, so that only males are born. The spread of the Y-drive would result in a population crash of the targeted species.

And then there's a potential solution to a big agricultural problem: weeds and pests that develop resistance to herbicides and pesticides over time. Researchers could create sensitizing gene drives that would replace resistant alleles with their vulnerable ancestral equivalents and thus restore the effectiveness of the pest-exterminating treatments.

Naturally, the development of a technology this powerful freaks some people out. The Hastings...