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Scorpion genome decoded

Arachnid’s DNA reveals how the animal survives its own venom

IN ITS DNA  Deciphering the complete genetic makeup of the scorpion Mesobuthus martensii (shown) reveals how it uses its tail, resists its own venom and handles plant toxins.

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This may sting a little: Scorpions have about 10,000 more genes than humans do.

The Chinese golden scorpion, Mesobuthus martensii, has at least 32,016 genes, Zhijian Cao of Wuhan University in China and colleagues report October 15 in Nature Communications. Humans have just over 22,000 genes.  

The researchers found 116 genes that encode neurotoxins, including 45 previously unknown ones. Many of the neurotoxins paralyze proteins in cell membranes that open and close to generate electrical signals, which nerve cells use to communicate. Mutations in the scorpion’s own membrane protein genes make the arachnid immune to its own venom.

Scorpions also have 160 enzymes that help them digest fats and detoxify plant chemicals from the herbivorous insects they eat. Some of these enzymes transform a chemical called coumarin into fluorescent compounds that make the animals glow blue under UV light, the team found.

The animals also make a type of light-sensing protein called Mmopsin3 in their tails. The protein senses ultraviolet to blue light. At least 20 other proteins made in the scorpion’s tail help transmit the light signal from the skin to the brain, the researchers discovered.

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