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  • So infectious diseases, right?

  • Infectious diseases are still the main cause

  • of human suffering and death around the world.

  • Every year, millions of people die of diseases such as T.B., malaria, HIV,

  • around the world and even in the United States.

  • Every year, thousands of Americans die of seasonal flu.

  • Now of course, humans, we are creative. Right?

  • We have come up with ways to protect ourselves against these diseases.

  • We have drugs and vaccines.

  • And we're conscious -- we learn from our experiences

  • and come up with creative solutions.

  • We used to think we're alone in this, but now we know we're not.

  • We're not the only medical doctors.

  • Now we know that there's a lot of animals out there that can do it too.

  • Most famous, perhaps, chimpanzees.

  • Not so much different from us,

  • they can use plants to treat their intestinal parasites.

  • But the last few decades have shown us that other animals can do it too:

  • elephants, porcupines, sheep, goats, you name it.

  • And even more interesting than that is that recent discoveries are telling us

  • that insects and other little animals with smaller brains can use medication too.

  • The problem with infectious diseases, as we all know,

  • is that pathogens continue to evolve,

  • and a lot of the drugs that we have developed

  • are losing their efficacy.

  • And therefore, there is this great need to find new ways to discover drugs

  • that we can use against our diseases.

  • Now, I think that we should look at these animals,

  • and we can learn from them how to treat our own diseases.

  • As a biologist, I have been studying monarch butterflies for the last 10 years.

  • Now, monarchs are extremely famous for their spectacular migrations

  • from the U.S. and Canada down to Mexico every year,

  • where millions of them come together,

  • but it's not why I started studying them.

  • I study monarchs because they get sick.

  • They get sick like you. They get sick like me.

  • And I think what they do can tell us a lot about drugs

  • that we can develop for humans.

  • Now, the parasites that monarchs get infected with

  • are called ophryocystis elektroscirrha -- a mouthful.

  • What they do is they produce spores,

  • millions of spores on the outside of the butterfly

  • that are shown as little specks in between the scales of the butterfly.

  • And this is really detrimental to the monarch.

  • It shortens their lifespan,

  • it reduces their ability to fly,

  • it can even kill them before they're even adults.

  • Very detrimental parasite.

  • As part of my job, I spend a lot of time in the greenhouse growing plants,

  • and the reason for this is that monarchs are extremely picky eaters.

  • They only eat milkweed as larvae.

  • Luckily, there are several species of milkweed that they can use,

  • and all these milkweeds have cardenolides in them.

  • These are chemicals that are toxic.

  • They're toxic to most animals, but not to monarchs.

  • In fact, monarchs can take up the chemicals,

  • put it in their own bodies, and it makes them toxic

  • against their predators, such as birds.

  • And what they do, then, is advertise this toxicity

  • through their beautiful warning colorations

  • with this orange, black and white.

  • So what I did during my job is grow plants in the greenhouse,

  • different ones, different milkweeds.

  • Some were toxic, including the tropical milkweed,

  • with very high concentrations of these cardenolides.

  • And some were not toxic.

  • And then I fed them to monarchs.

  • Some of the monarchs were healthy. They had no disease.

  • But some of the monarchs were sick,

  • and what I found is that some of these milkweeds are medicinal,

  • meaning they reduce the disease symptoms in the monarch butterflies,

  • meaning these monarchs can live longer when they are infected

  • when feeding on these medicinal plants.

  • And when I found this, I had this idea,

  • and a lot of people said it was a crazy idea,

  • but I thought, what if monarchs can use this?

  • What if they can use these plants as their own form of medicine?

  • What if they can act as medical doctors?

  • So my team and I started doing experiments.

  • In the first types of experiments,

  • we had caterpillars, and gave them a choice:

  • medicinal milkweed versus non-medicinal milkweed.

  • And then we measured how much they ate of each species over their lifetime.

  • And the result, as so often in science, was boring:

  • Fifty percent of their food was medicinal. Fifty percent was not.

  • These caterpillars didn't do anything for their own welfare.

  • So then we moved on to adult butterflies,

  • and we started asking the question

  • whether it's the mothers that can medicate their offspring.

  • Can the mothers lay their eggs on medicinal milkweed

  • that will make their future offspring less sick?

  • We have done these experiments now over several years,

  • and always get the same results.

  • What we do is we put a monarch in a big cage,

  • a medicinal plant on one side, a non-medicinal plant on the other side,

  • and then we measure the number of eggs that the monarchs lay on each plant.

  • And what we find when we do that is always the same.

  • What we find is that the monarchs strongly prefer the medicinal milkweed.

  • In other words, what these females are doing

  • is they're laying 68 percent of their eggs in the medicinal milkweed.

  • Intriguingly, what they do is they actually transmit the parasites

  • when they're laying the eggs.

  • They cannot prevent this.

  • They can also not medicate themselves.

  • But what these experiments tell us

  • is that these monarchs, these mothers, can lay their eggs on medicinal milkweed

  • that will make their future offspring less sick.

  • Now, this is a really important discovery, I think,

  • not just because it tells us something cool about nature,

  • but also because it may tell us something more about how we should find drugs.

  • Now, these are animals that are very small

  • and we tend to think of them as very simple.

  • They have tiny little brains,

  • yet they can do this very sophisticated medication.

  • Now, we know that even today, most of our drugs

  • derive from natural products, including plants,

  • and in indigenous cultures,

  • traditional healers often look at animals to find new drugs.

  • In this way, elephants have told us how to treat stomach upset,

  • and porcupines have told people how to treat bloody diarrhea.

  • What I think is important, though, is to move beyond

  • these large-brained mammals and give these guys more credit,

  • these simple animals, these insects that we tend to think of

  • as very, very simple with tiny little brains.

  • The discovery that these animals can also use medication

  • opens up completely new avenues,

  • and I think that maybe one day, we will be treating human diseases

  • with drugs that were first discovered by butterflies,

  • and I think that is an amazing opportunity worth pursuing.

  • Thank you so much.

  • (Applause)

So infectious diseases, right?

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B1 US TED medicinal monarch toxic sick medication

【TED】Jaap de Roode: How butterflies self-medicate (Jaap de Roode: How butterflies self-medicate)

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    CUChou posted on 2015/03/24
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