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Genetic mutation discovered that gives scorpions their sting

Dr. Shunyi Zhu and colleagues from the Chinese Academy of Sciences in Beijing, China published the first derivation of the evolution of the toxin in scorpion stings that was reported in the Jan. 14, 2014, edition of the journal Molecular Biology and Evolution.

A scorpion under a black light. In normal lighting, this scorpion appears black.
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Many plants and animals are known to produce chemicals called defensins that protect the animal and plants from predators, disease, and pests.

Dr. Zhu determined that the protein that produces the neurotoxin in the scorpion’s sting evolved through the change in a single genetic deletion event that converted a nontoxic defensin into the neurotoxin venom that scorpions display at present.

Zhu examined the possible derivations of the scorpion’s potassium channel inhibitor peptides from scorpion venom neurotoxins known as α-KTxs. The development of the neurotoxin capacity in scorpion venom was found to be not only beneficial to the scorpion but was a direct result of greater stability in the structure of the resulting venom toxin due to minimization of steric hindrance in the molecule that makes up the scorpion venom toxin versus the stability of the originating defensin.

The first scorpions appeared on Earth about 430 million years ago. The exact timing f the development of a neurotoxic sting in scorpions is not known but the mechanism that favored that development has been defined.