A powerful new technique called a "gene drive" is opening up incredible possibilities for the control and manipulation of wildlife. Leading researchers say we need to have a debate now about whether we should be shaping the genetics of whole populations of wild animals.
A number of technologies have come together in recent years that are enabling scientists to manipulate genomes in profound ways. Among them is a tool known as CRISPR-Cas9, a technique that allows researchers to rewrite an organism's DNA. Eventually, scientists will combine this gene-editing technique with gene drives — the deliberate insertion of "selfish genes" that appear more frequently in offspring than normal genes, which will have a 50-50 chance of being passed on.
It's called a gene drive because it would allow scientists to drive a gene through a wild population of animals, such as mosquitoes, frogs, and weeds. Once introduced, nature would do the rest.
Mosquitoes in particular offer an enticing example. Researchers have already figured out a way to engineer malarial mosquitoes such that they produce an overabundance of males. The eventual imbalance following a gene drive would help reduce the mosquito population and spread of the disease.
Via Nova Next: "Here, a mosquito with a gene drive (blue) mates with a mosquito without one (grey). In the offspring, one chromosome will have the drive. The endonuclease then slices into the drive-free DNA. When the strand gets repaired, the cell's machinery uses the drive chromosome as a template, unwittingly copying the drive into the break."
Powerful, powerful stuff. But also fraught with risks. That's why a group of scientists are starting the debate. Yesterday, a group of U.S. researchers called for greater oversight of this powerful genetic technology. Writing in Science Insider, Elizabeth Pennisi explains more:
[MIT's Kennth] Oye hopes that the Science article will expose many more scientists to the idea of gene drive technology. In addition, in eLife today, [geneticist George] Church's group describes the potential of CRISPR to speed up gene drive technology, as well as the possible limitations of gene drive approaches. "In the case of [g]ene drives, it is the pests which are engineered and the solution spreads automatically," Church says.
The paper presents no results, but Church says that Esvelt is well into testing CRISPR-generated gene drive approaches in yeast, nematodes, and mosquitoes. The goal is to test the potential of the altered genes to spread to other species and other populations. "We want to be absolutely sure before releasing [gene drive modified organisms] that it's not going to escape from the species in which we are putting it," Burt says.
There are other concerns as well, says James Collins, an evolutionary ecologist at Arizona State University, Tempe, who co-organized the workshops with Oye and is another co-author on the Science paper. Gene drive technology may one day make it possible to drive invasive species to extinction or to make herbicide- or pesticide-resistant pests susceptible again. But despite the best efforts of scientists to improve health and agriculture, Collins says, "we've learned it's still possible for evolution to take the system in a direction that's not planned." To avoid such a disaster, he adds, "we still need a basic understanding of the genome and how genes move through ecological systems and a basic understanding of what the loss of species means to a community."
Personally, I think gene drives are a brilliant idea. In addition to adding novel organisms and synthetic animals into the environment (not to mention robots and nanotechnological devices), the genetic manipulation of existing species will grant us further control over the Earth's biosphere. Doing it safely and effectively will be a monumental challenge, but by no means an intractable one. We're rapidly approaching the dawn of an era in which autonomous Darwinian process will be usurped by intelligent oversight and control.
Mosquito image via Nova Next.