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The World's Deadliest Mushroom is Getting Deadlier - Video học tiếng Anh
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The World's Deadliest Mushroom is Getting Deadlier
The World's Deadliest Mushroom is Getting Deadlier
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0:00
Among mushroom foragers, the Death Cap is infamous.
0:03
It's the most poisonous known mushroom in the world,
0:07
and just half of one contains enough poison to kill you.
0:10
This little guy may look unassuming, but it's responsible for
0:14
90 percent of poisonous mushroom deaths globally.
0:17
So you might assume that it's about as bad as it could be.
0:20
But you would be wrong.
0:22
Because recent research shows that the Death Cap
0:25
is developing new toxins that may make it even deadlier.
0:30
[♪ INTRO]
0:33
Meet Amanita phalloides, commonly known as the death cap.
0:37
Appearance-wise, they’re pretty innocuous.
0:39
With a white stem, a yellowy-brown cap, and beautiful gills along the underside,
0:44
they look pretty much like any basic drawing of a mushroom.
0:47
But they have that ominous name for a reason.
0:50
They pack a double punch of being easily mistaken for friendly snacks
0:54
like the puffball or straw mushroom, and having some of the
0:57
highest toxin levels per gram out of any other species of mushroom.
1:01
With these guys, there’s not mush-room for error...I’m sorry.
1:06
Death caps have allegedly been behind the deaths of many historical figures,
1:09
including the accidental poisoning of Pope Clement VII,
1:13
and the murders of Holy Roman Emperor Charles VI
1:16
and Roman Emperor Claudius.
1:18
Now, we don’t generally tell you what to do here at SciShow,
1:21
but if you are a Roman emperor, just stay away from mushrooms!
1:24
Death caps are tough to neutralize, too.
1:26
Unlike some other mushrooms, even cooking or
1:28
drying does not keep you safe from their toxins.
1:31
Don’t believe me?
1:31
Ask the family of a woman in Australia who, in 2023,
1:35
cooked up beef wellington made with death cap
1:37
mushrooms that had been dehydrated.
1:39
Oh wait. You can’t.
1:40
It turns out she did it on purpose — they are dead, because they where murdered.
1:44
It probably seemed like the perfect crime,
1:46
because you might not notice that something is wrong right away.
1:49
The first symptoms only start about 6 hours after your meal,
1:52
and then it’s nausea, vomiting, and diarrhea for up to 36 hours.
1:56
You’ll even start to feel better for a while.
1:59
If you go to the hospital for your early symptoms, you might be discharged.
2:02
But in the background, the death cap toxins are settling into your kidneys and liver.
2:07
Ultimately, that’s what kills you: liver failure 3-5 days after eating the mushroom.
2:12
So, yeah. These mushrooms are definitely deadly.
2:15
A. phalloides jams your system with three main types of toxins,
2:19
but the one that’s the worst for humans is called amatoxin.
2:22
Amatoxin permanently binds to an enzyme called RNA polymerase II
2:26
and stops it from doing its very important job
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of transcribing all of your genes into proteins.
2:31
And it works so fast that when your liver and kidneys try to do their usual work of
2:35
filtering toxins out of your body, they can’t clear it out and end up
2:39
getting stuffed with the very poison they’re trying to get rid of.
2:43
But even after all of that, the survival rate of death cap poisoning
2:46
is still estimated to be around 80-90%.
2:49
So odds are a quick brush with death cap will not be the end of you.
2:53
But to boost your chances, it’s important to get treatment as soon as possible.
2:57
While there are still no official antidotes to amatoxin poisoning,
3:01
doctors can give you activated charcoal to soak some of it up,
3:05
or certain medications to try to prevent too much amatoxin from reaching your liver.
3:09
And you want to do that soon,
3:11
because once enough of your liver and kidney cells die off,
3:14
that damage is permanent.
3:15
In some situations, even people who survive death cap poisoning
3:19
might need a liver transplant or kidney dialysis.
3:22
But before I get to the part about this toxic mushroom gaining even more toxins,
3:26
I need to pause for a quick break.
3:29
This SciShow video is supported by Brilliant:
3:32
a company that shares our love for curiosity,
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4:05
To learn for free on Brilliant for a full 30 days, go to brilliant.org/scishow,
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4:15
They’re also giving you unlimited daily access to
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4:23
Now, we could not get a death cap to speak with us on the record,
4:26
but it doesn’t seem that they’re targeting us on purpose.
4:29
Humans are probably just unlucky victims as
4:32
this mushroom adapts to its environment.
4:34
Remember that 6 hour delayed toxicity?
4:36
It doesn’t stop humans from eating the mushroom in the first place,
4:39
so that gives us a pretty good idea that death cap poisons aren’t really all about us.
4:44
In fact, people who have eaten a death cap and
4:45
lived to tell the tale have reported that it’s actually pretty dang tasty.
4:49
But not worth it.
4:50
Don’t eat death caps
4:51
So if they’re not deterring us, some scientists think that the death cap’s toxins
4:55
help ward off smaller predators, like pests and rival fungi.
4:59
This would mean that A. phalloides might have
5:01
developed amatoxin as a defense against mushroom-eating insects.
5:05
Now, some species of the Drosophila fly have developed a resistance to amatoxin,
5:10
so it’s not a perfect defense.
5:11
But the flies wouldn’t need to evolve a specific
5:14
resistance to it if the toxin didn’t affect them significantly.
5:18
So this makes some researchers support the insect deterrence idea.
5:22
Another possibility is that these toxins help death caps
5:25
establish a symbiotic relationship with the trees they grow on.
5:28
The thing is, because of that relationship,
5:30
A. phalloides are difficult to study in a lab setting.
5:34
Not too many labs have extra room for a bunch of trees,
5:37
however nice the atmosphere would be.
5:39
So while we know for sure that they’re toxic to humans and dogs,
5:42
studies on toxicity in other species are spore-adic at best.
5:47
Sporadic? SPORE-adic?
5:49
And that’s not great because these mushrooms
5:51
have started invading new territories.
5:53
They used to be European exclusives,
5:55
but now they’ve spread their deadly poisons across North America and Australia.
5:59
And a 2023 publication found that as A. phalloides
6:02
adapts to new environments, it’s coming up with new toxins.
6:06
They’re killing it out there! Sometimes literally.
6:09
This was studied in 88 death caps across California and Europe.
6:13
Researchers were specifically assessing a group of genes called MSDIN genes,
6:18
responsible for coding the most potent of the death cap toxins,
6:22
including the ones most deadly to humans.
6:24
They found that these MSDIN genes have become significantly
6:28
different between the US and European varieties.
6:31
And they seem to be undergoing very strong natural selection.
6:34
See, each individual mushroom has a slightly different sequence of MSDIN genes.
6:39
But, despite that variation, some regions of the genome
6:42
stay pretty much the same no matter where the mushroom is growing.
6:45
The fact that some of the genome has stuck around,
6:48
despite other parts being different, suggests that those retained parts of the
6:51
MSDIN genes, and the amatoxins they encode, probably aren’t just a coincidence.
6:57
Death caps are probably developing new poisons in new environments
7:01
because something about those toxins is helpful
7:04
for keeping the next generation thriving.
7:06
So it’s quite possible that these selectively-refined toxins have helped
7:10
A. phalloides successfully sprawl across the globe.
7:13
Caps off to evolution as always.
7:15
And that’s just what we know from the few death cap genomes we’ve looked at!
7:19
There’s a huge diversity of MSDIN genes among A. phalloides,
7:23
so they’ve made many new toxins that we humans have yet to study.
7:26
So, the moral or perhaps morel of the story is not to
7:29
eat anything that you have foraged unless you are 100% sure.
7:33
As for me, I’ll probably stick to the ones I can buy in the store.
7:37
[♪ OUTRO]
