In a few short years, the technology that led to the creation of GMO plants — and a worldwide disruption of agricultural systems — may seem as quaint as a pale plastic Macintosh, or as ponderous as a magnetic-tape UNIVAC.
“Gene drive,” a new laboratory technique emerging on biotech’s far frontier, is changing the way scientists understand and engineer inheritance. Its ability to transform life’s code at the cellular level has been compared to a viral infection or nuclear chain reaction. If all works according to theory, the changes to an organism targeted for gene-drive modification would be rapid, permanent and alarmingly unpredictable. Advocates for the technology promise weeds that lower defenses to profitable herbicides, mosquitoes that avoid family picnics like the plague, and even young rodents unwilling to carry on the family business of dispensing a plague. Critics imagine a dystopia of genetic terrorism, virulent pandemics and immense ecological devastation.
“Geneticists have tried using genome-editing tools to build custom gene drives, but the process was laborious and expensive,” Tim De Chant and Eleanor Nelsen explain in PBS’ popular NOVA documentary series. “With the discovery of CRISPR-Cas9 as a genome editing tool in 2012, though, that barrier evaporated. CRISPR is an ancient bacterial immune system which identifies the DNA of invading viruses and sends in an endonuclease, like Cas9, to chew it up. Researchers quickly realized that Cas9 could easily be reprogrammed to recognize nearly any sequence of DNA. …
“Gene drives and Cas9 are each powerful on their own, but together they could significantly change biology. CRISRP-Cas9 allows researchers to edit genomes with unprecedented speed, and gene drives allow engineered genes to cheat the system, even if the altered gene weakens the organism. Simply by being coupled to a gene drive, an engineered gene can race throughout a population before it is weeded out.”
Britain’s Independent newspaper notes that gene drive technology will allow laboratory-designed mutations “to be amplified within a breeding population of insects or other animals without any further intervention once the trait has been initially introduced. This is the case even if the trait is non-beneficial to the organism. Laboratory experiments on fruit flies have shown that a modified gene introduced into one individual fly can take just a few generations to ‘infect’ practically every other fly in the breeding population, in defiance of the normal rules of genetics which dictate a far slower spread.”
“Researchers once spent months, even years, attempting to rewrite an organism’s DNA. Now they spend days,” observe the PBS authors. “With gene drives — so named because they drive a gene through a population — researchers just have to slip a new gene into a drive system and let nature take care of the rest. Subsequent generations of whatever species we choose to modify — frogs, weeds, mosquitoes — will have more and more individuals with that gene until, eventually, it’s everywhere.”
One prominent gene drive researcher captured the promise and peril of this brave new world. Harvard Medical School’s Dr. Kevin Esvelt told the Independent: “If we’re right about this, it’s a powerful advance that could make the world a much better place. But only if we use it wisely.”
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