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Scientists Just Proved a Theory in the Coolest Way Ever

The topic? B.O. Proof? GENETIC ENGINEERING


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Sam Westreich

3 years ago | 5 min read

Remember in Jurassic Park, the movie, how an animated Mr. DNA explained to the main characters (and, by extension, the viewers) how dinosaurs were resurrected after 65 million years of extinction through gene editing?

It’s an idea that was purely science fiction at the time that Michael Crichton wrote it, but we are getting closer and closer to having the tools shown in the video (although escaped dino disasters still aren’t likely, for other reasons).

When I watched this sequence, I was fascinated by the idea. This was, in part, what pushed me towards my current career, what encouraged me to pursue an advanced degree in genetics.

Recently, a headline caught my attention. Researchers at the University of York had published a paper, where they identified the key gene responsible for smelly sweat.

But it’s not the discovery itself that caught my attention. Rather, it’s how they proved that their discovery was real.

Let me explain.

The Findings of the Paper

First off, what did these researchers identify?

They found that the primary source of odor coming from armpits isn’t actually our own body — it’s an odor that’s produced by bacteria who feast on the sweat that we produce.

This is a great example of how we don’t live in a vacuum. We hear more about the gut microbiome, the bacterial community inside our intestinal tract, but we have microbiomes on practically every surface, including on our skin, in our soil, and in various bodies of water.

Even in a general area, like on our skin, our microbiome differs from region to region. Your face is exposed to different conditions than your armpits, and so it’s understandable why there are different bacterial populations living in these two different areas.

The researchers found that the smell of bad odor, or “B.O.”, comes from compounds called thioalcohols. These aren’t the only smelly molecule in B.O., but they’re the most pungent.

Our body doesn’t produce thioalcohols, however. They arise as a side product from microbial digestion, after bacteria in our armpits eat the precursor molecules that come out of our glands.

(Why do we make these precursor molecules, by the way? It’s still not fully understood, although prevailing theories suggest that it likely is an intentional way for us to emit certain scents.)

But these precursor molecules quickly become food for bacteria — namely, Staphylococcus hominis, a particular species with a voracious appetite for the thioalcohol precursors. The researchers identified the specific enzyme that S. hominis uses to break these precursors apart, discarding the smelly thioalcohols as waste products for us to smell.

But how do these researchers prove that the specific enzyme, called C-T lyase, makes the stench?

Easy enough — through genetic engineering.

A Futuristic Gene Editing Technology, Used Now

Here’s the situation. We have Staphylococcus hominis, which produces an enzyme called C-T lyase that makes smelly byproducts.

We also have another bacterium, Staphylococcus aureus, that doesn’t play any role in body odor, and doesn’t make C-T lyase.

The scientists simply took the gene to produce C-T lyase and inserted it into S. aureus, giving it the ability to digest thioalcohol precursors, and then waited to see if it made a smelly mess.

Spoiler alert — it did. Once it had the DNA to produce that enzyme, it could eat the precursors, and leave bad body odor as its leftovers.

Science!

Pictured: Science! Call me a nerd all you want, but it’s so freaking cool. Photo by National Cancer Institute on Unsplash

This isn’t the first time that we’ve used genetic engineering to put new genes into new organisms. Consider vitamin supplements — most of the vitamins B2, B12, and vitamin C that we consume are made by bacteria that have been genetically modified to create these vitamins.

Still, it’s amazing to see how far we’ve come in modifying the genes of bacteria. What previously would have been on the front page of a scientific journal — modifying the genome of a living organism — is now just a small paragraph in the Methods section, explaining how they proved the purpose of this C-T lyase enzyme.

Especially in bacteria, gene knock-outs (turning off a gene) or gene addition is a fairly easy, straightforward process. There are even basic kits for it, with easy-to-follow instructions (just search for CRISPR kits).

But genetic engineering still faces some challenges.

How Long Until I’m Genetically Modified?

It’s a question that comes up almost every time that genetic engineering is raised:

“How long until we can modify people?”

It’s a topic worthy of its own article, but the short answer is that we still have some big hurdles to overcome.

First is the problem of off-target effects.

The human genome is three BILLION base pairs long. It’s very tough to make a change to one specific region and not also cause accidental changes in other areas. And accidental changes can lead to disease or cancer, so it’s very important to be accurate.

Second, at least for adult humans, you need a way to get your new gene + machinery into every single cell. We don’t have a good way to do this. That’s why most proposals for genetic engineering suggest doing it to a fertilized egg, when the entire human consists of just a couple cells, instead of more than 10 trillion cells.

Finally, there’s the challenge of regulating whatever you put in. Some of our DNA is genes, but the rest of our DNA is instructions for when those genes should be turned on or off, and for how long. We can’t just add a new gene — we need to also add instructions for its use.

Add all these challenges together, and we’re not likely to see full-body genetic engineering be offered for adult humans any time soon. Sorry.

It’s astounding to realize how far our scientific methods have come. Even in a paper that’s investigating a specific enzyme in bacteria responsible for body odor, we can see cutting-edge scientific techniques at work.

Adding new genes to bacteria, allowing them to gain new abilities (such as the ability to make smelly compounds from our sweat emissions) is now a common tactic for demonstrating evidence that our understanding is correct.

If Michael Crichton, the author of Jurassic Park, were alive to see these new advances, I think he’d be thrilled — and he’d probably point to it and say “I told you that it was possible!”.

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