Why don't poisonous animals poison themselves?
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Why Dont Poisonous Animals Poison themselves
Some animals, such as the pitohui bird and the poison dart frog, have a remarkable ability to produce and store toxins in their skin or feathers that can deter predators or even kill them. But how do they avoid poisoning themselves with their own weapons?
The mystery of the sodium channels
The toxins that these animals use are called batrachotoxins, and they work by blocking the sodium channels in the cells of their prey. Sodium channels are essential for transmitting nerve impulses, muscle contractions, and brain activity. When they are blocked, the cells become paralyzed and eventually die.
But the poisonous animals have a trick up their sleeve: they have evolved sodium channels that are resistant to batrachotoxins. This means that the toxins do not affect their own cells, and they can safely carry them around without harming themselves.
The discovery of the toxin sponge
But how did they evolve such resistance? For decades, the best theory has been that the birds and frogs developed mutations in their sodium channel genes that changed their shape and made them less vulnerable to the toxins. However, this theory had a problem: it could not explain why some closely related species that share the same sodium channel genes were not poisonous.
A recent study by researchers from the University of California, San Francisco, has solved this puzzle by finding a new piece of the puzzle: a protein called saxiphilin that acts as a toxin sponge. Saxiphilin is found in the blood of the poisonous animals, and it binds to batrachotoxins with high affinity, preventing them from reaching the sodium channels. This way, saxiphilin protects the animals from their own toxins, as well as from those of other poisonous species.
The researchers also discovered that saxiphilin is derived from another protein called transferrin, which is involved in iron transport in the blood. They suggest that saxiphilin evolved from transferrin by acquiring mutations that made it bind to batrachotoxins instead of iron. This is an example of how evolution can reuse existing genes for new functions.
The implications of the toxin sponge
The discovery of saxiphilin has important implications for understanding how poisonous animals evolved and diversified. It also opens up new possibilities for studying how toxins interact with proteins and how they can be used for medical purposes.
For example, saxiphilin could be used as an antidote for batrachotoxin poisoning, or as a tool to isolate and identify new toxins from nature. It could also help to design drugs that target sodium channels for treating diseases such as epilepsy, pain, and cardiac arrhythmias.
Poisonous animals are fascinating creatures that have developed amazing adaptations to survive and thrive in their environments. By uncovering their secrets, we can learn more about the diversity and complexity of life on Earth.
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