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Poisonous arthropods: Centipede bite kills in a flash

In Europe, the representatives of the articulated group of centipedes are quite inconspicuous, but impressive specimens of Asian provenance can reach a length of 25 centimeters. Such specimens - representatives of the genus Scolopendra - One should only approach it with caution: If they bite with their imposing front legs, which have been transformed into poisonous claws, it is at least extremely painful for humans. Smaller animals are worse off, and anything below the size of macaques must fear for its life. Even in small doses, the centipede's peptide poison causes rapid death because it inhibits certain potassium channels in the victim's cells, researchers now describe in "PNAS".

Centipedes occur worldwide in a wide variety of habitats (from deep caves to public parks), but mostly eke out a rather inconspicuous existence in the temperate latitudes. The larger centipedes of the tropics are more noticeable: They are known for not being afraid of prey that are significantly larger than themselves. The potent poison that they inject into the victim when they bite contributes to the success of the hunt: a cocktail of toxins that has been under scrutiny by pharmacologists for some time because of its diverse neurological effects.

This article is included in Spectrum - The Week, 04/2018

A research team led by Ren Lai from the Chinese Academy of Sciences in Yunnan has now investigated the cause of the poison's deadly effect on small animals in more detail. A Chinese redhead centipede weighing around three grams (Scolopendra subspinipes mutilans)According to the researchers after experiments, a 45-gram laboratory mouse with around 30 microliters of injected venom kills within half a minute. A peptide called "Ssm Spooky Toxin (SsTx)" turned out to be the lethal component of the poison, which is highly effective in inhibiting all of the victims' potassium channels belonging to the KCNQ family. As a result, the regulation of the pulmonary vascular and arterial resistance collapses, so that the vessels constrict sharply, which ultimately leads to a massive rise in blood pressure, insufficient oxygen supply and death. As an antidote, the anticonvulsant epilepsy drug retigabine helps - if it is administered in time, the scientists found out.