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The Fungus You Should Actually Be Worried About
The Fungus You Should Actually Be Worried About
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Untertitel (331)
0:00
In the not-too-distant future, a fungus called Cordyceps will mutate
0:03
in response to a warming planet, and evolve the ability to infect humans.
0:08
The fungus takes over its victims’ brains, turning them into zombies,
0:12
hellbent on consuming every living person they can find.
0:15
The resulting panic will create a dystopian world
0:18
where our survival is far from guaranteed.
0:21
Sounds... bad. Lucky for you, that’s just the plot of The Last of Us,
0:25
and not a prediction of the actual future.
0:27
As far as we know, anyway.
0:28
But if you played the game or watched the show and have been
0:31
worried about Cordyceps becoming a reality, I do have some bad news for you,
0:36
also some good news, and then some really bad news.
0:39
The bad news is that the Cordyceps fungus is real,
0:42
and does cause zombie epidemics.
0:44
The good news is that it mainly targets insects and spiders, not humans.
0:49
So you don't have to worry about it...for now.
0:51
But the really bad news is that there are plenty of other fungi out there that have
0:55
the potential to become a disaster for us, and fungal infections are on the rise.
1:01
Which is why researchers like Asiya Gusa are so important.
1:05
Her work to understand how fungi adapt to changing environments,
1:08
and what they could mean for our health,
1:11
can help us prepare for whatever they throw at us.
1:14
We sent our friend Madelyn Leembruggen to Duke University to tour Gusa’s lab
1:18
and get a firsthand look at the potential threat.
1:21
Get ready for another SciShow Field Trip!
1:24
[♪ INTRO]
1:28
Thanks, Hank! He’s such a fun-guy.
1:30
Stop me if you’ve heard this one before.
1:32
One day, totally out of the blue, a new pathogen evolves from
1:36
something more benign, and this new bug is very good at making us sick.
1:41
It’s highly contagious, we don’t have great medicines or vaccines for it,
1:45
and the sudden surge of sick people throws the entire world into chaos.
1:48
If you’re having flashbacks to sanitizing our groceries in 2020,
1:52
well, I don’t blame you.
1:54
But when we talk about pandemics, we tend to think of viruses or bacteria,
1:58
things like the flu or COVID or tuberculosis.
2:01
What we usually don’t think of are fungi.
2:04
Fortunately, Asiya Gusa does.
2:07
Gusa is an Assistant Professor of Molecular Genetics and Microbiology
2:10
at Duke University, where she spends her days studying fungi
2:14
that have the potential to cause dangerous infections.
2:17
So as you can imagine, she talks a lot about fungus.
2:20
I noticed that you said fungi. I say fungi.
2:25
Fungi, fungi, fungi, however you want to say it is actually okay.
2:28
Okay. Is there like debate in the community about everyone talking
2:33
about whether or not you want to use a hard g or not?
2:36
I've landed on fungi, but whatever makes you comfortable.
2:38
One of your body's great defenses against fungi
2:41
is the fact that you are, well, kind of hot.
2:44
And I mean that literally.
2:46
So why are fungal infections not very common in humans?
2:49
It's a really good question, and we think that it's actually a lot of it
2:52
has to do with our higher body temperature.
2:54
So our higher body temperature serves as a natural kind of thermal barrier.
2:58
Since most environmental fungi that we breathe in in the environment,
3:02
they actually can't grow that well at our body temperature.
3:05
They prefer cooler temperatures, like around 25 to 30 degrees Celsius,
3:09
because they live in the soils and they live on plant matter.
3:12
So we actually have sort of a natural defense mechanism
3:16
of our higher body temperature.
3:17
But there’s a group of fungi that have the potential to change that,
3:21
which is why Gusa and her team are studying them.
3:23
They’re called Cryptococcus.
3:25
These fungi are already known to cause serious infections
3:28
in some immunocompromised people.
3:30
That’s because, even though our body heat holds most fungi at bay,
3:34
our immune systems still have to finish them off.
3:36
And as the planet warms, Cryptococcus might be adapting to survive better and for
3:41
longer at the higher temperatures that usually keep them out of all of our bodies.
3:45
So actually, in the laboratory, we study a species of Cryptococcus
3:49
that's less thermal tolerant, so it can't survive well at body temperature.
3:54
And so those are the ones we're most interested in studying and figuring out if,
3:57
if they cross that temperature threshold,
4:00
they are possibly going to cause a greater number of disease,
4:04
increase in incidents, and also severity of disease.
4:08
Organisms are constantly adapting to the world around them,
4:11
and some of them, like Cryptococcus, are very good at doing that.
4:16
Like all living things, these fungi are always mutating,
4:19
sometimes based on random changes to single base pairs in their DNA.
4:23
These little changes can add up over time,
4:25
creating big alterations in how the organism functions.
4:29
What we're in right now is a big 30 degree incubator.
4:32
So think of like a walk in fridge.
4:34
Like a cold room, for example.
4:36
Same thing, but the opposite.
4:37
That’s Cheyenne Lee, a postdoc working in Gusa’s lab.
4:40
The reason that we have this here, basically is the cryptococcus cells
4:44
that we grow primarily grow at 30 degrees Celsius.
4:48
So in this room, they're not feeling the stress.
4:50
Yeah, they’re not feeling that heat temperature stress.
4:52
So these are just some little crypto cells on the plate.
4:56
And then I have another one that was previously grown at 37 degrees.
5:00
So you'll notice that
5:01
There's fewer of them
5:02
There's a lot smaller colonies on the plate,
5:04
because they were very stressed out at that higher temperature.
5:08
I also get stressed when it’s too hot.
5:10
Me too!
5:10
In addition to getting stressed in the heat,
5:13
something interesting changes about the way Cryptococcus mutates.
5:16
Gusa found that the mutation rate is connected to the temperature
5:20
around the fungus while it’s growing.
5:22
When Cryptococcus was grown at 37 degrees Celsius,
5:25
it mutated five times faster compared to when it was grown
5:30
at its more typical 30 degrees Celsius.
5:32
But what Gusa found even more interesting about her studies was
5:36
how Cryptococcus was mutating.
5:38
These weren't just single base pair changes that were accumulating.
5:42
There were these big chunks of DNA actually jumping around, called,
5:45
well, jumping genes, or transposable elements.
5:49
These transposable elements can have a big impact on how genes are expressed.
5:54
I even got a hands-on look at how they study these jumping genes!
5:57
What I'm going to actually show you guys today is how do we check to see,
6:03
has that jumping gene actually jumped?
6:05
You know? So that's what I'm going to be looking at here.
6:08
We're going to see how the jumping gene, jumps.
6:10
Yes.
6:11
We’re about to do a test called gel electrophoresis.
6:13
The researchers isolate a segment of DNA, chop it up,
6:16
and stick it on a gel plate, which they run an electric current through.
6:20
This causes the DNA to sort itself by size,
6:23
and those bigger pieces are where the jumping genes landed.
6:26
So if you want, do you remember how I loaded that at the very beginning?
6:30
You've been watching this.
6:31
Yeah yeah.
6:32
Do you feel brave?
6:34
I can be brave.
6:35
All right, so what I'm gonna have you do is load one of those.
6:37
We have to be very gentle and load slow. Gentle, very go slow, okay.
6:37
So that's it. But you got it. You'll be fine.
6:37
You can live that right next to where I just put mine.
6:38
Okay, yeah. So here's that first stop, okay, there you go, wonderful, okay,
6:41
and then right next to her, yes, or wherever you want, really,
6:45
wherever you're comfortable. I'll work around it. That's perfect, beautiful.
6:48
So many times, did you see it taller than the line?
6:48
Yeah, a little left in there.
6:48
That's okay, oh, like, get it towards the end, and there you go.
6:51
Now press the rest of it.
6:53
There you go. Perfect. All right, that should be enough. You got it. You got it.
6:57
So now the next button that you can press is right there.
7:00
Press on it. Yay! Great job, you did it!
7:03
Thank you for teaching me to pipette!
7:04
Combined with the rapid rate of mutation, these jumping genes can lead to the
7:08
kind of heat tolerance that some species of Cryptococcus have shown lately.
7:12
As if that’s not bad enough, Gusa found that this higher mutation rate
7:16
can give Cryptococcus a really nasty superpower: Drug resistance.
7:21
So these are the drug resistant colonies, basically on both of these plates
7:25
37 degrees these were the ones that were stressed out.
7:27
You can see, just like on the other plates, they were a lot less.
7:30
And what we're looking at are spontaneous, drug resistant mutants.
7:35
So if you grow up a population of cells, a small percentage of them
7:39
will have a mutation that will allow them to grow on a drug containing plate.
7:43
And so this is kind of a proxy for us to figure out if there's been a mutation
7:48
that has caused this particular phenotype to arise,
7:51
which is drug resistance in this case.
7:53
So then we can actually go in, extract the DNA and find out what
7:57
that genetic change has occurred.
7:59
And in some cases, we find transposable elements
8:02
have inserted into our gene causing the drug resistance.
8:05
Even the drugs that currently exist for Cryptococcus aren’t great.
8:08
The ideal treatment involves multiple antifungal drugs,
8:12
which are often toxic and difficult for people to handle.
8:15
Gusa told us that one of the biggest challenges in treating these
8:18
more serious fungal infections is that there just hasn't been
8:21
a lot of research done to improve these antifungal drugs.
8:25
And so what we really need are better drugs to treat fungal diseases
8:29
and just to be prepared in case we need fungal vaccines.
8:32
Right now, there are no fungal vaccines to treat humans,
8:35
and so that's a big concern.
8:36
And then a lot of the drugs that we have to
8:38
treat fungal infections were very antiquated.
8:40
They were developed a long time ago.
8:42
They actually have a lot of toxic side effects,
8:45
so more investment is needed in developing effective drugs and drugs
8:48
that people can take, potentially orally, to treat fungal infections that are invasive.
8:52
That’s another potential benefit of Gusa’s research.
8:55
If she can identify the conditions and substances that kill certain fungi,
9:00
it could lead to promising antifungal treatments.
9:03
For example, the fungus that makes penicillin, Pennicillium,
9:06
makes its own antibiotics to reduce resource
9:09
competition in its environment by killing nearby bacteria.
9:12
Why is it so important to keep exploring and to keep finding new fungi?
9:16
Well, again, as I'm learning, fungi are amazing natural resources
9:21
that have been underutilized, and so just like with the study of bacteria,
9:26
which people know a lot more about, with fungi,
9:28
they also can produce all these amazing compounds.
9:31
There's undiscovered potential for them in a lot of different realms.
9:34
So fungi have a long history of being exploited for their ability to treat
9:41
not only other fungi, to kill other fungi, but to kill bacteria.
9:45
They're also involved in statins for like cholesterol,
9:49
psilocybin is being studied for potential antidepressant activity.
9:53
There's lots of different uses for fungi, and for the most part,
9:56
we really, we value and we gain a lot of amazing products from fungi.
10:02
And we're actually now starting to look at ways in which fungi,
10:05
since they're natural decomposers in our environment,
10:07
that they may be able to degrade plastics.
10:10
So one of my newest students is actually working on a plastic pollution project
10:13
where we're screening fungi for the ability to break down compounds
10:17
that are much more difficult to break down by the enzymes that we currently have.
10:21
And so this is one of the reasons or resources that sort of an unexpected find
10:25
in our science, that we can actually utilize fungi,
10:29
not only to be just afraid of them,
10:32
but what can we actually harness the power of fungi to do in our laboratory?
10:36
How many like, if you had to estimate what percentage of fungi
10:42
in the world we've already learned about what percentage do you think that is?
10:47
I think I've seen figures like this, and they put it like we probably surveyed,
10:51
about 3% of what's actually out there.
10:53
Yeah, fungi are historically understudied,
10:57
and there's so many different varieties,
10:58
you can probably go into your background
11:00
and your backyard and actually find a new fungal species.
11:02
Gusa’s team has started to close this gap, and it began in an unusual way.
11:07
In September of 2024, Hurricane Helene swept across
11:11
the southeastern part of the US and was particularly devastating to
11:15
Southern Appalachia, killing at least 250 people and leading to
11:19
flooding that caused immense damage.
11:21
In the aftermath, Gusa and her team visited the areas
11:24
that had been flooded with one specific goal: to collect fungi.
11:29
And so these were isolated after Hurricane Helene,
11:32
we went and did environmental sampling,
11:34
and we've been able to curate this amazing resource that can now be used
11:38
for potentially natural product discovery and also to understand
11:42
what kinds of mycotoxins or harmful allergens
11:46
they might be producing that might be making people sick.
11:49
Gusa’s lab collected hundreds of fungal samples from Black Mountain,
11:52
North Carolina, an area that was hit especially hard by Hurricane Helene.
11:57
The team has catalogued all sorts of important information like the species,
12:01
origins, and genetic sequence to create a fungal biobank.
12:05
We have quite a variety we wanted to show you
12:08
of just different phenotypes on the different plates.
12:10
We talked with Sam Shaltz and Gabrielle Walker to learn more.
12:13
But basically what happened is we got a swab of all these
12:16
different environmental samples,
12:17
and my job is to go through and try to isolate out different species.
12:22
And then once they're isolated out,
12:23
this is a good example of them being isolated on different types of plates.
12:27
I then go through and I have to identify them.
12:30
So you've, you're basically starting this, like big library of fungi.
12:36
Yeah, yeah. And we have, again, we have a lot of species right now.
12:40
I think we have about 65 in our biobank.
12:42
At the moment, all of them have been isolated and identified,
12:47
41 unique species, and out of them,
12:49
about 10 of them are potential fungal pathogens.
12:52
What kinds of things are you looking for from
12:54
the biobank as you assemble all these samples?
12:57
So we're trying to just basically find out the fungal abundance.
13:01
The neat thing is that we can track which sample we have here,
13:06
where the swab came from.
13:07
And then the one neat thing too, is with our fungal biobank,
13:11
we also are recording the pictures as well.
13:14
So this will be also very useful for people in the future to reference
13:18
making sure that when they do use our samples,
13:20
they can look at our pictures and make sure that what
13:23
they're growing looks like what we have growing here.
13:26
In addition to investigating which fungi might lead to infections,
13:29
Gusa’s lab will use the biobank to conduct research
13:32
on potentially dangerous chemicals that fungi can make.
13:35
We have other researchers at Duke.
13:37
There are my collaborators that are going to be looking
13:39
at what kind of toxins do fungi produce as they're consuming different materials.
13:44
So when they're growing on things like drywall or on the surfaces of plastics,
13:48
what are they actually producing as they metabolize?
13:51
And so some of the things that they secrete into the air, in addition to spores,
13:56
are things known as mycotoxins and also volatile organic compounds.
14:01
You know that musty, earthy smell in a damp basement?
14:05
That’s partly made up of VOCs, cooked up by fungus.
14:08
The effect of VOCs on our health is less clear,
14:12
which is why Gusa wants to study them.
14:14
So this is sort of a whole new area of research that has been under studied again,
14:18
and we really don't have an idea about what kind of health impacts result,
14:22
but we certainly know that we already know of certain allergens
14:25
that are caused by some of these fungi that are growing from indoor mold sources.
14:29
But we want to learn more about mycotoxins and VOCs.
14:32
Having this biobank might even help us identify
14:34
some of those fungus-fighting-fungi we were talking about before.
14:38
Or, we may even find fungi that can help us in other ways.
14:42
So this is the one of the fungal species that I'm working with right now
14:46
to identify to be able to degrade plastic.
14:50
And so from what I found, from some of our preliminary results
14:54
is that this species can degrade a polyester polyurethane polymer called Inferno,
15:01
and it's doing really amazing.
15:02
So what some of my next steps are is identifying what enzymes
15:07
are being secreted by Aspergillus that can degrade that particular polymer.
15:12
And we think that this is a possibility that we can
15:14
go from natural disaster to natural discovery, and that's really exciting
15:17
I have to admit that when our lab first started,
15:20
it was kind of all about the doom and gloom,
15:22
oh, the threat of fungi and like, you know, disease and you know,
15:25
which is very serious, and we really do care about it,
15:27
but it was nice to have another side where we can also talk about
15:31
the solutions that fungi might be able to provide.
15:33
And so that's been really exciting, and a nice balance in the lab.
15:37
All this is especially cool because the Gusa lab is still pretty new,
15:41
and they’re only just getting started.
15:43
Gusa had a different path to becoming a research scientist than most.
15:47
After earning her PhD, she spent a fair bit of time as a high school science teacher.
15:51
I got to be able to learn how to communicate science and really inspire,
15:54
hopefully, the next, future generation of scientists.
15:57
And so I had this really incredible opportunity to come back a little bit
16:00
later in life to be a researcher at Duke University,
16:03
which has been one of my dreams.
16:05
And so now, instead of, you know, teaching in the classroom,
16:07
I have a classroom in the laboratory,
16:09
and I'm able to really mentor my students and, like,
16:12
really see them grow and thrive in their own right.
16:15
So it's been really exciting transition for me.
16:17
And as it turns out, when we got here we realized she’s already a SciShow fan.
16:21
Did you ever use SciShow videos?
16:25
I sure did. Yeah. Hank Green, you were a constant in my classroom.
16:29
Yeah. So just the way that SciShow broke things down,
16:33
it was able to really just augment the lectures I had in
16:35
a fun and very relatable way with our students.
16:38
So I know when I told my lab that, you know, SciShow was coming to our lab,
16:41
they were super excited.
16:42
They're like, what are you serious?
16:44
I can't wait to be a part of this.
16:46
So yeah, we're really excited that you guys were able to come and visit with us.
16:49
We're so excited you guys joined our ecosystem,
16:52
and now you and your research get to go be in other classrooms.
16:56
It's full circle.
16:58
Yeah absolutely.
16:59
The work that Gusa and her lab are doing is vital for helping us understand
17:03
why and how fungi can be so dangerous to us,
17:06
and even let us develop new medicines, too.
17:09
All of which could be very useful… whether we’re facing down
17:13
just a bit of mold overgrowth, or a full-on fungal zombie apocalypse.
17:18
SciShow Field Trips are made with our friends at HHMI Tangled Bank Studios.
17:22
We’ve come together to bring you face to face with researchers
17:25
at the cutting edge of scientific discovery.
17:27
You can watch more of Tangled Bank’s science content at tangledbankstudios.org.
17:32
[♪ OUTRO]
