Imagine we could stop mosquitoes from carrying malaria ...
for good. Or prevent ticks from transmitting Lyme disease. Or eliminate the billions
of dollars of damage caused by bugs to our food supply each year. Gene drives are a radical
new approach to genetic engineering that could help us achieve these goals, and a
whole lot more besides. Yet as you might expect, the technology is not risk free.
Gene drives are designed to eliminate unwanted traits in insects and other
animals. They work by pushing out genetic modifications through whole species,
until eventually, every critter has been changed into something we have
intentionally engineered.
The idea isn't especially new. But it's only very recently that advanced gene editing
techniques have made human designed gene drives possible. And at the heart of this
revolution is a new technique for precision engineering genes: Clustered Regularly
Interspaced Short Palindromic Repeats... or if you're not into brain bending tongue
twisters, CRISPR for short. CRISPR uses specially designed molecules that run along the
strands of DNA in an organism's genome, and seek out specific sequences of
genetic code. Once found, they snip out the old code, and paste in the new. It's
essentially a sophisticated biological search and replace technology that allows
scientists to easily modify the genetic traits of an organism, such as replacing
the parts where a mosquito's genome that allows it to host malaria-causing
parasites for instance.
Unfortunately, on its own, CRISPR isn't so effective. Every time a CRISPR mosquito mates
with a wild one, its genetically modified DNA is diluted down, meaning that some of
its offspring will still be able to carry the malaria parasite. And this is
where the genius of crisper-enabled
gene drives comes in. Imagine what would happen if that replaced sequence in
the CRISPR mosquito, also contained a little bit of code that continued to search and replace
parasite-enabling DNA sequences. When the mosquito mated, the built-in code would ensure
that every single one of its progeny would inherit the same traits, as well as
inheriting the CRISPR code that would ensure the anti-malaria gene was
passed on to every future generation. In other words, the new gene will be irresistibly
driven through the whole mosquito population. And eventually, every mosquito
will become a human-designed malaria-free insect. And this is not a technology
that's restricted to mosquitoes. Any organism that reproduces by sharing DNA
through sexual intercourse is fair game. That said, designing an effective and responsible
gene drive isn't a piece of cake. Working out which genes to change in an organism for
instance, is still in an inexact science. Especially when the CRISPR search
and replace may modify more genetic sequences than expected,
or introduced anticipated traits. The speed with which new genes can be driven
through spaces also depends on how frequently they reproduce. Gene drives
are in principle great for transforming fast-breeding organisms like insects. Yet it would
take millennia to push a gene drive through a relatively slow breeding species like ...
humans, for instance. And that's assuming that naturally occurring genetic
mutations don't mess up the re-coding
in the meantime. Nevertheless, gene drives
do radically change how we're able to manipulate nature. And that also
means they raised tough questions around risk and responsibility. For instance, we
don't yet know how gene drives might harmfully disrupt ecosystems, or create
unexpected risks to other species humans include it and we're not sure how much hard wiring in
certain genetic traits will weaken an organism's ability to adapt to changing
environments especially when those traits would normally be rejected
through natural selection and then there's the danger of entrepreneur's and
hobbyists even with nature just because they can or people who intentionally set
out to create even more dangerous pieces weaponized super mosquitoes possibly
hunger games like speeches designed to maim and kill not to mention the
possibility of groups starting exclusive human gene drives that will give their
future is genetically enhanced abilities because of concerns like these
scientists have already started to think about how gene drives might get out of
hand
recommendations are beginning to emerge from responsible practices like testing
grounds in the lab before trying them out in the environment and there's talk
of countermeasures such as the one gene drives that can remember changes of
Pollock the propagation of genetic modifications get these discussions
often assume that it's the scientists and the developers who know what's best
I suspect though that when it comes to intentionally redesigning natural
speeches there are a lot more people who'd like a say in what should and
should not but
especially as the risks and benefits of June drives are likely to affect far
more people than those who came up with the private idea in the first place
which leaves the question if the use of Green drives or a social issue as much
as a scientific one how can ordinary people become involved in ensuring we
get it right or it's too late
if you have any thoughts on this please do share them in the comments below and
as always stay safe