This episode is brought to you by the Music for Scientists album,
now available on all streaming services.
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200 years from now, it's entirely possible that we will have people living off-Earth full time,
either on another planet like Mars, or in some kinda space station.
By then, we'll probably be pros at living in low-gravity environments.
We'll have figured out how to solve the problems we have today,
like how spaceflight can take a toll on the heart and immune system.
And when we get to that next big chapter of humanity,
we'll have a tiny test subject to thank: fruit flies.
While they may not seem like useful stand-ins for humans,
fruit flies have more in common with us than you might think.
Many fruit fly genes mirror the functions of human ones,
making them useful in understanding what those genes do.
And they also have some characteristics
that make them especially great for studies performed in space.
For one, they don’t take up a lot of room,
which is super important in an environment where space is limited.
Thousands of flies can be housed in a container the size of a deck of cards.
Also, their lifespan is only about two weeks,
so scientists can study several generations of them in a month.
So, fruit flies have been sent to space over and over again
to test different effects of spaceflight, especially how microgravity affects living bodies.
And while we still have plenty of questions, they are already teaching us a lot.
For instance, in space, the heart acts a little differently.
Like, among other things, its muscles get weaker since they’re not fighting gravity.
We know this is true of other muscles as well, but considering how important the heart is,
figuring out exactly how it changes in microgravity
will be huge for our long-term future in space.
And these are, of course, things we’re studying in humans,
but we can only send so many people to the Space Station at a time.
Which means we can only learn so much
about exactly what’s happening to the heart and how to combat it.
So one study, published in November 2020, used more than 200 fruit flies
as a model for how spaceflight affects cardiac disease and function.
The scientists found that flies living in microgravity had smaller hearts
that weren’t as effective at pumping blood, which is similar to what can happen to astronauts.
But the researchers also found the flies had problems
creating the proteins needed to keep the heart working properly.
So now, that’s something else for cardiac researchers to keep an eye on.
And eventually, studying these proteins
could accelerate the development of new treatments, especially for longer missions.
But as important as our hearts are,
one area of fly research that’s been especially fruitful is studying the immune system.
Astronauts experience a suppression of their immune system
during and right after spaceflight that makes them more susceptible to infection.
And flies offer a very specific advantage for helping us understand how and why.
See, the human immune system has two branches: innate and adaptive.
The innate immune system is something you are born with.
It’s essentially a system of barriers
that protect against foreign particles like viruses, bacteria, and parasites.
These include physical barriers like your skin,
and general immune responses like inflammation.
Meanwhile, the adaptive immune system is the part that
learns to respond to threats as it’s exposed to them, using specialized cells and antibodies.
Untangling what each branch does and how it changes in space
is somehow even harder than it sounds.
And that’s where fruit flies come in.
They do not have adaptive immune systems; that’s limited to us vertebrates.
So they can allow us to really dial into just how the innate immune system works
without the whole other part getting in the way and confusing things.
The key with the innate immune system is that, for it to work,
your body has to recognize pathogens as foreign objects.
Then, it can work on fighting them.
To do that, the innate immune system uses molecules called receptors
to bind and recognize other molecules on the surface of infectious agents,
like bacteria and viruses.
And when it comes to spaceflight, studies have found that the immune system
can become impaired when communication to these receptors is disrupted.
Like, a 2014 study showed that fruit flies born and raised aboard the space shuttle Discovery
were a lot more susceptible to certain infections compared to flies on Earth.
But in that study, only one of the two receptor systems the researchers looked at was impaired,
the one that responds to fungal infections.
The other, which responds to certain types of bacterial infection, was unaffected.
They haven’t quite figured out why, and propose
that it could have something to do with how the specific proteins act in each system.
But it could mean that the fungal receptor is more sensitive to disruption in microgravity.
Which would suggest that the effects on the innate immune system
aren’t the same across the board.
Meanwhile, the study also found that fruit flies that experienced increased gravity,
which happens during launch and reentry, had a boosted immune response to fungus.
Again, it’s not clear why.
Maybe it’s that something about the proteins is more stable in hypergravity.
But maybe, somehow intentionally subjecting astronauts to increased gravity
could have therapeutic uses on long-duration missions.
Or maybe it just means we need to
put more time and research into developing anti-fungal coatings.
To extend space fly research even further,
NASA established the Fruit Fly Lab onboard the ISS in 2015.
This small, long-term housing for the flies allows
more in-depth study than those on the Space Shuttle,
such as studying the effects of spaceflight on the interactions between a microbe and host.
And results from this lab are still coming in,
teaching us even more about how our immune systems work in space.
So, it seems weird that we’d use those buzzing nuisances
always drowning in your tea to learn about ourselves.
And even weirder that we would launch them into space,
taking them to the one place where we can finally be free of them, to do it!
But researchers are carrying out even more experiments using the Fruit Fly Lab
to learn more about immunity and life in microgravity.
Meaning fruit flies still have more to teach us about what living in space is really like.
So someday, when our first people do move off-Earth permanently,
they’ll not only know what to expect, but how to stay as healthy as possible.
And whether you’re a fruit fly, a human astronaut or a regular ole earthling like me,
all our lives are better when we have good music to listen to.
Patrick Olson created the Music for Scientists album as a celebration of the beauty of science,
and an homage to the people who make science happen, on Earth, and in space!
It’s a gift from Patrick Olson to scientists to thank them
for making the world known to us, but it’s something we all can enjoy.
So give it a listen! We’ve got a link in the description all ready for you!
And thank you for your support.
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