Why don’t poison frogs poison themselves? — Speaking of Chemistry

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Even though they are tiny and adorable, poison frogs wield some of the world’s deadliest natural substances. But have you ever wondered how they are immune to their own poisons ?
Like many other types of the animals, poison frogs use chemicals to defend themselves against predators, and like similarly poisonous creatures, they have evolved a way to resist the deadly effects of their own toxins.
Poison frogs are a collection of more than 300 frog species from central and south America.
Although it may sound odd, not all poison frogs are actually poisonous. The species that are steal toxins from the ants and mites that they eat and they store the compounds in glands in their skin for later defense. Their bright colours are warning to predators. To learn more about these frogs and how they pull off using poison has protection, we spoke with evolutionary biologist Rebecca Tarvin and neurobiologist Cecillia Borghese.
So when the frogs are stressed or they feel threatened by a predator they release these toxins on their skin which actually exposes themselves to their own toxins. Scientists are only just now learning how poison frogs protect themselves from these toxins.
But they’ve got a leg up in solving the mystery using past research and other poisonous creatures to guide them.
It’s been a lot of differents types of animals that use poison as a defence, and in fact people have been studying thist problem in insect for decades.
Insects, amphibians and reptiles that use these compounds have a molecular trick that helps keeps them safe.
To exert its deadly effects, a toxin typically targets a particular protein in the cells of an animal under attack.
Once the toxin binds, the protein stops working properly, causing the cells to go haywire But if the binding site on these proteins were mutated, meaning that one or two of there amino acids was replaced, the toxin could no longer bind. It would lose his deadly punch. For example, golden poison frogs carry a powerful toxin called Batrachotoxin.
Batrachotoxin binds to voltage gated sodium channels on the surface of cells in animals and humans alike. This locks the channels open causing them to malfunction. Because these channels are vital to nerve signaling, holding them open ultimately leads to paralysis and death.
So how do these frogs avoid paralyzing themselves? Swapping an amino acid called Asparagine for a different one called Threonine in the voltage gated sodium channel. This switcheroo suddenly changes the site of the protein where Batrachotoxin normally binds rendering the frog sodium channel immune to the toxin.
Tarvin, Borghese and their collaborators founds another intriguing example of toxin resistance in a different group of frogs in Ecuador.
These poison frogs carry a toxic compound called Epibatidine. To inflict its damage, Epibatidine binds to nicotinic Acetylcholine receptors on the surface of nerves and muscles cells. Normally a chemical messenger called acetylcholine binds to these receptors, allowing ions to move in and out of the cells through a pore. This helps the cells send neurochemical signals that make the muscles contract. Epibatidine, however, makes the receptors more sensitive, keeps the pore open longer and causes hypertension, respiratory paralysis, seizures and death.
The frogs that carry this nasty compound all have the same mutation on their nicotinic acetylcholine receptors. Changing a serine to a cysteine in just the right spot keeps epibatidine from binding to the receptors. The problem for these frogs is that the mutation also blocks acetylcholine, making the receptors non functionals. So the tiny creatures have also evolved a couple other mutations in the receptors to make sure acetylcholine, but not the toxin, can still bind.

C. Borghese- That was truly fascinating when it comes to how nature managed to evolve a mechanism in which the toxin gets completely, does not act anymore, while the normal ligand is still perfectly functioning and they are both binding in the exact same place. It was extremely striking.

This delicate balancing act helps explain why we can’t all evolve resistance to these deadly compounds. These kinds of mutations often come at the cost of reduced or altered protein function. If you are not routinely exposed to the toxin, it makes much more sense to keep things running or hopping, as usual.

Outroduction:
Have you spotted an interesting chemical adaptation from the animal world ? I really like how some garter snakes have evolved resistance to their toxic newt prey. Tell us yours in the comments.

There are no notes for this quiz.
Even though they are tiny and adorable, poison frogs wield some of the world’s deadliest natural substances. But have you ever wondered how they are immune to their own poisons ?
Like many other types of the animals, poison frogs use chemicals to defend themselves against predators, and like similarly poisonous creatures, they have evolved a way to resist the deadly effects of their own toxins.
Poison frogs are a collection of more than 300 frog species from central and south America.
Although it may sound odd, not all poison frogs are actually poisonous. The species that are steal toxins from the ants and mites that they eat and they store the compounds in glands in their skin for later defense. Their bright colours are warning to predators. To learn more about these frogs and how they pull off using poison has protection, we spoke with evolutionary biologist Rebecca Tarvin and neurobiologist Cecillia Borghese.
So when the frogs are stressed or they feel threatened by a predator they release these toxins on their skin which actually exposes themselves to their own toxins. Scientists are only just now learning how poison frogs protect themselves from these toxins.
But they’ve got a leg up in solving the mystery using past research and other poisonous creatures to guide them.
It’s been a lot of differents types of animals that use poison as a defence, and in fact people have been studying thist problem in insect for decades.
Insects, amphibians and reptiles that use these compounds have a molecular trick that helps keeps them safe.
To exert its deadly effects, a toxin typically targets a particular protein in the cells of an animal under attack.
Once the toxin binds, the protein stops working properly, causing the cells to go haywire But if the binding site on these proteins were mutated, meaning that one or two of there amino acids was replaced, the toxin could no longer bind. It would lose his deadly punch. For example, golden poison frogs carry a powerful toxin called Batrachotoxin.
Batrachotoxin binds to voltage gated sodium channels on the surface of cells in animals and humans alike. This locks the channels open causing them to malfunction. Because these channels are vital to nerve signaling, holding them open ultimately leads to paralysis and death.
So how do these frogs avoid paralyzing themselves? Swapping an amino acid called Asparagine for a different one called Threonine in the voltage gated sodium channel. This switcheroo suddenly changes the site of the protein where Batrachotoxin normally binds rendering the frog sodium channel immune to the toxin.
Tarvin, Borghese and their collaborators founds another intriguing example of toxin resistance in a different group of frogs in Ecuador.
These poison frogs carry a toxic compound called Epibatidine. To inflict its damage, Epibatidine binds to nicotinic Acetylcholine receptors on the surface of nerves and muscles cells. Normally a chemical messenger called acetylcholine binds to these receptors, allowing ions to move in and out of the cells through a pore. This helps the cells send neurochemical signals that make the muscles contract. Epibatidine, however, makes the receptors more sensitive, keeps the pore open longer and causes hypertension, respiratory paralysis, seizures and death.
The frogs that carry this nasty compound all have the same mutation on their nicotinic acetylcholine receptors. Changing a serine to a cysteine in just the right spot keeps epibatidine from binding to the receptors. The problem for these frogs is that the mutation also blocks acetylcholine, making the receptors non functionals. So the tiny creatures have also evolved a couple other mutations in the receptors to make sure acetylcholine, but not the toxin, can still bind.

C. Borghese- That was truly fascinating when it comes to how nature managed to evolve a mechanism in which the toxin gets completely, does not act anymore, while the normal ligand is still perfectly functioning and they are both binding in the exact same place. It was extremely striking.

This delicate balancing act helps explain why we can’t all evolve resistance to these deadly compounds. These kinds of mutations often come at the cost of reduced or altered protein function. If you are not routinely exposed to the toxin, it makes much more sense to keep things running or hopping, as usual.

Outroduction:
Have you spotted an interesting chemical adaptation from the animal world ? I really like how some garter snakes have evolved resistance to their toxic newt prey. Tell us yours in the comments.

There are no notes for this quiz.
+23 -16
Quiz #: 33496
This video explains how poison frogs use chemicals to defend themselves against predators without poisoning themselves.
Quiz by: IUTALILLE1
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