- Saving lives or powering extinctions?
It's all in how you drive.
(grimy dub step music)
A few months back we
talked about a new tool
in genetic modification
called CRISPR Cas9.
This technology is based
on bacterial immune systems
and it allow us to make
edits to an organism's genome
with more speed, accuracy and ease
than ever before and in
this exciting new landscape
of genetic modification
and synthetic biology,
there's one particular application
I wanted to talk about.
Gene drives.
These have the potential
to save millions of lives,
and give us unprecedented
control over the natural world.
They also could potentially come with some
major risks that need to
be studied and understood.
So before we get started,
what exactly are gene drives?
Gene drives work biasing
the inheritance of genes.
Normally a sexually reproducing organism
comprises it's genome 50 50
from the genetic information
of it's parents.
Gene drives change this.
In a literal sense, a
gene drive is a mechanism,
such as CRISPR, attached
to an organisms chromosomes
and it actually biases the way those genes
are passed along.
Instead of there being a 50% chance
of passing along a marked gene,
you can have a near 100% chance of passing
it down to offspring and that offspring
would have a near 100% chance of passing
it along to it's offspring and so on.
What this means in the real world
is that we could use gene drives
to spread genetic modifications
in the wild to any organism
that reproduces sexually and has
a relativity fast reproductive cycle
and here's the crazy thing.
Those genetic modifications
don't necessarily
benefit the organism.
They could reduce its fitness.
In other words, gene
drives could literally
break the rules of natural selection.
For example, let's talk about malaria.
The World Health Organization said that
in 2015, there was 214
million cases of malaria
and 438,000 people died of the disease.
Malaria is carried by mosquitoes.
So what if we could
genetically modify mosquitoes
so that they were incapable
of carrying malaria?
But how can you insure that
the genetically modified
mosquito will pass that
genetic information
sufficiently in the wild.
With normal mating, the
engineered mosquitoes
might not reproduce quickly enough
and that genetic
information could fade away
but with gene drives, it can persist
and within a couple of years,
you could eliminate
malaria carrying mosquitoes
or how about in the case
of invasive species.
For example, humans introduced rats
to the Galapagos Islands and rats remain
an enormous threat to
the Galapagos tortoises.
So much so that
conservationists have resorted
to using rat poison in great amounts
but what if you could genetically modify
a rat so that it produces
more male offspring
than female offspring?
After a few generations of this,
you wouldn't have enough female rats
to perpetuate the species
and it would disappear from the island.
Ah I hear you ask.
What happens if one of these
genetically modified rats
makes it back to the mainland?
(dramatic classical music)
Yeah, that would be a huge problem
and there are a lot of bioethicists
who suggest we use extreme caution
before ever using gene drives
in a practical application
in the real world
and there are a lot of researchers
who are working on
parallel safety measures
to go along with gene drives.
Such as requiring there be specific
genetic elements in
place for the gene drive
to persist and after a few generations
those genetic elements begin to disappear
and the gene drives are no longer viable.
That limits how many
generations of organism
actually have that gene drive.
Even with those safety measures in mind,
we need to remember that gene drives
have the potential for
great good and great harm.
So I've got a question for all of you.
Do you think gene drives are a good tool
for us to use in the future?
If so, in what capacity
and what safety measures
do you think we need to put in place
to keep it in check?
I want to hear you thoughts
in the comments below.
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