Why centipedes can't kill each other with their venom

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Why centipedes can't kill each other with their venom
Why centipedes can't kill each other with their venom
Anonim

Chinese molecular biologists have figured out how the venom of one of the scolopendra species affects their own nerve cells. Scientists have explained why their bites kill other animals, but they never cause significant harm to their relatives. The findings of the researchers were published in the scientific journal Science Advances.

“Many animals use the same poisons for a variety of purposes - foraging, protecting from predators and resolving conflicts with congeners., but at the same time killing their victims. This discovery suggests that the evolution of poison, centipedes and their victims are interconnected, - the researchers write.

Over the past decade, biochemists and biologists have used poisons extracted from marine and land animals to create a variety of medicines. For example, at the beginning of the last decade, biochemists from France created a powerful analgesic, Mambalgin, based on the poison of a dangerous African snake, the black mamba, which is not addictive.

Typically, the venom of snakes, scorpions, spiders and other venomous animals contains many proteins and signaling molecules. After being bitten, they enter receptors or ion channels on the surface of the victim's nerve cells and prevent them from working. As a rule, this leads to paralysis or convulsions, which ultimately causes the death of the bitten.

It is interesting that if some poisonous animals bite their relative, then they do not harm them or act on them in a different way. Molecular biologists, under the guidance of Professor Ren Lai of the Zoological Institute of the Chinese Academy of Sciences, have found out why such selectivity is characteristic of the Scolopendra subspinipes venom. These large centipedes are found in East Asia and Australia.

Dual-use poison

Like other members of this family, these invertebrates are active predators. They hunt spiders, scorpions, insects, snails and even try to attack small mice or lizards. These scolopendra behave just as aggressively towards congeners.

Lai and his colleagues tracked how the poison affects the nerve cells and tissues of the body of scolopendra and other invertebrates. They tried to understand which receptors of neurons the molecules from the composition of the poison act on. It turned out that scolopendra toxins affect several types of ion channels. The predators themselves and their prey have a different set of these channels.

In particular, if the poison enters the body of a scolopendra, it blocks the work of nerve cells, the surface of which is covered with receptors of the Shal species. When scientists turned them off, the centipede was paralyzed for about ten minutes. After that, the work of the Shal channels was restored, and when the concentration of the main active substance of the poison, the SsTx protein, dropped to a certain critical level, the scolopendra could move again.

If the poison penetrated into the body of other living beings, then it acted on another ion channel, Shaker. Its blockage leads to the already permanent paralysis and death of the centipede victim, especially if it is relatively small.

As Chinese biologists have found out, the differences in the nature of the action of SsTx on millipedes and other animals were due to the fact that in one of their genes, which controls the production (that is, "encodes") the protein components of Shaker, there is a point mutation that protects their nerve cells from the action of the toxin. When scientists removed this mutation from the millipede DNA, their cells immediately lost their immunity to the effects of their own poison.

A similar, but opposite in meaning, mutation is in the gene that encodes the Shal receptor, the analogs of which in the cells of other animals are not affected by the poison of scorlopendra. Both of these unique features of the receptors allow scolopendra to distinguish "us" from "outsiders" and spend less resources, using the same poison both for food production and for intraspecific competition, scientists conclude.

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