Natures wonders: Australian stinging tree (Introduction)

by David Turell , Wednesday, September 16, 2020, 20:18 (1527 days ago) @ David Turell

The venom is similar to spider venom:

https://phys.org/news/2020-09-native-tree-toxins-pain-spiders.html

"The Gympie-Gympie stinging tree is one of the world's most venomous plants and causes extreme long-lasting pain.

"Associate Professor Irina Vetter, Dr. Thomas Durek and their teams at UQ's Institute for Molecular Bioscience found a new family of toxins, which they've named 'gympietides' after the Gympie-Gympie stinging tree.

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"'The Australian stinging tree species are particularly notorious for producing excruciatingly painful sting, which unlike those of their European and North American relatives can cause symptoms that last for days or weeks.

"'Like other stinging plants such as nettles, the giant stinging tree is covered in needle-like appendages called trichomes that are around five millimetres in length—the trichomes look like fine hairs, but actually act like hypodermic needles that inject toxins when they make contact with skin," Associate Professor Vetter said.

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The team did find such neurotoxins—a completely new class of miniproteins that they termed "Gympietides", after the indigenous name for the plant.

"Although they come from a plant, the gympietides are similar to spider and cone snail toxins in the way they fold into their 3-D molecular structures and target the same pain receptors—this arguably makes the Gympie-Gympie tree a truly "venomous" plant.

"Associate Professor Vetter said the long-lasting pain from the stinging tree may be explained by the gympietides permanently changing the sodium channels in the sensory neurons, not due to the fine hairs getting stuck in the skin.

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"The researchers point to two possibilities for the toxin's evolution from either an ancestral gene in an ancient shared ancestor or convergent evolution, where nature re-invents the most fitting structure to fit a common purpose."

Comment: The suggestion of convergent evolution raised the observation that perhaps only so many molecules are available in a form that cause this type of reaction.