Gene Drive

Something that I'm interested in looking at as a Global Scholar will be epidemiology. Along that vein, climate change is going to make disease-related issues worse. The higher temperatures will be better for mosquitoes to spread infections, which will really put pressure on us as a society. How will we remedy this? Guess what: there's a neat little thing called CRISPR that we have now that we can use to hopefully deal with this problem. I'm also going to use this opportunity to clear up with CRISPR is and why it's a pretty cool discovery. Everyone knows that humans have immune systems: that's why we can fend off those pesky colds and flus. However, lesser known is the fact that other organisms have equivalent defense systems, namely plants (very interesting, but not too relevant yet) and interestingly enough, microorganisms such as bacteria. CRISPR stands for clustered regularly interspaced short palindromic repeats. Quite a mouthful. What's important here is the "short palindromic repeats" are actually DNA segments derived from infective agents such as viruses that can target bacteria held by the bacterium as a sort of memory. These segments can be then used to generate Cas enzymes, which can cut up the pathogenic DNA. What's important here is the specificity of the response. We can use this same mechanism to edit specific locations in genomes of any animal (because of the ubiquity of the genetic code) and thus, why not mosquitoes? Mosquitoes suck. Anopheles sucks. Aedes aegypti sucks. What can we do to fight these little vampires and prevent them from killing millions worldwide? The answer is very intriguing actually: it's the gene drive. The gene drive is an idea that could potentially decimate mosquito populations worldwide. How it works is it essentially guarantees a 100% inheritance rate of a gene of interest. This is important because this gene can be something like early death or some kind of trait that makes mosquitoes more readily targeted by predators. If there is a 100% inheritance rate, then we can be sure that the gene of interest propagates in the population, and will have major effects in that way. The mechanism involves CRISPR: there are hypothetically two individuals, one with a "wild-type" genome and one with an edited genome, or the genome with the segment of interest. The segment of interest has a part that codes for the Cas protein, which cuts out a segment on the wild-type genome. What happens now is that the wild-type genome tries to repair itself, but does so by replacing the hole in its genome with the segment of interest, including the gene. Of course, we have to think about whether mosquitoes might develop some type of immunity to this kind of innovation, but for now, let's talk about the effects of this on a global scale. This is an issue that has vast implications for the world: it's hard to say what the effects of wiping out an entire species of mosquitoes will be. What we do know is that there are no places in which mosquitoes are keystone species, meaning that if they are wiped out, the entire environment is doomed. However, there are certainly some organisms that are reliant on mosquitoes as a source of food, including some species of fish. It's hard to say if there will be any unintended consequences to this action (as there usually are with such grand-scale changes). This situation isn't analogous to wiping out a disease like smallpox, for instance. That had purely deleterious effects; mosquitoes actually do provide a significant food source to some species. I guess if this technology gets implemented, we'll find out if we really want mosquitoes to buzz of or not. That's my two cents on this issue. I suspect I'll have a harsher opinion on this when summer arrives and mosquitoes come back to annoy everyone.