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Australia’s stinging trees: Remember not to grow them



The doctrine that hides Australia’s giant prickly trees, of the genus Dendrocnide, is perhaps as dubious as it is great. Stories abound in nightmarish encounters with the magazine’s hypodermic needle-like hair that injects a toxin that drives men crazy and has asked horses to throw themselves off rocks.

Some of these stories are centuries old and cannot be confirmed. But as Edward Gilding can attest, these legends contain at least one truth lick: the absolute pain of being stung by the fine, downy hairs that adorn the leaves and stems of Dendrocnide. The trees, which can grow higher than 1

00 feet, are found in the rainforests of eastern Australia, where they are known to torment hikers.

“It’s like having a nail pushed into your flesh,” said Dr. Gilding, a biologist at the University of Queensland and self-described sting connoisseur.

The sting from the hairs of the trees also has an enormous staying power, picking out anguish in waves for hours or days. Some anecdotes have reported intermittent pain lasting months. a few particularly bad plugs have even landed people in the hospital.

For most victims, such prolonged misery can be an incentive enough to avoid the plants. But Dr. Gilding and a couple of like-minded masochistic colleagues have instead worked to decipher what gives Dendrocnide its blow.

Dozens of experiments and countless plugs later, they have identified some of the ingredients involved. As they report on Wednesday in the journal Science Advances, Australia’s stinging trees are filled with a toxin that, when injected, adheres to pain-detecting cells in the recipient and causes them to become haywire, locking the affected area into the molecular equivalent of an infinite. cry. .

“So many things cause pain, and so little is known about why,” said Isaac Chiu, a neurobiologist at Harvard University who was not involved in the study. Dr. Chiu noted that the toxins of the trees target a molecule found on nerve cells that is “fundamental to mammalian pain,” he said. “If this reveals something that blocks it, it would be really exciting.”

The painful strength of dendrocnide plants has bedeviled scientists for decades. The trees injure people so often that many of their habitats are marked by warning signs and warn careless visitors to “beware of the stinging tree.” People who visit these forests sometimes have respirators, heavy gloves and a handful of antihistamines.

But even researchers driven enough to inject themselves with extracts made from tree toxins have not been able to determine the source of the sting, said Irina Vetter, a pain researcher at the University of Queensland and an author of the new examination.

These ethically gray experiments can no longer be performed, said Dr. Vetter. But she, Dr. Gilding and their colleagues were still able to separate the chemical components of the toxin from two Dendrocnide species and create synthetic versions of the compounds in the laboratory. A very small protein found in both plants caused mice to lick and sip at the sites where it was injected. Dumped down on nerve cells, the molecule turned the trigger-happy cells into an “on” position and forced them to send a stream of signals.

The researchers named the minute, pain-inducing molecules gympietides, as a tribute to gympie-gympie, the word for stinging wood in the language of the Gubbi Gubbi people, a group of indigenous Australians.

Dr. Vetter was amazed to find out that high school days resembled toxins made from poisonous spiders and cone snails that use the chemicals to carry out their unhappy prey.

“These are three vastly different groups of organisms – spiders, cones and now these trees – that produce a toxin that is very similar,” said Shabnam Mohammadi, a toxin researcher at the University of Nebraska-Lincoln who was not involved in the study.

It is a great example, she added, that different branches of the tree of life converge on the same solution.

Researchers are not sure how the toxin benefits Dendrocnid trees. Perhaps it acts as a kind of chemical armor to ward off hungry herbivores, said Dr. Vetter. But some animals, such as beetles and paddle melons – small kangaroos for relatives – seem to munch on Dendrocnide foliage, prickly spines and everything else.

Dr. Chiu and Dr. Mohammadi both said they suspect that gymnastics times are not the only factors that make Dendrocnid toxin so difficult to take, especially given the bizarre and persistent side effects of the plants. Some of Dr. Vetter’s previous crossings with the trees have, among other things, resulted in pain in her chest and shot discomfort in her extremities.

“I think they just scratched the surface of what these plants contain,” said Dr. Mohammadi.

Until more of these mystery ingredients are identified, Dr. Gilford to steer clear of prickly trees. “If you work with the plant, it is virtually impossible not to get stung,” he said.

This challenge is made more difficult by the plant’s inviting appearance, noted Dr. Gilford. The same hairs that can deliver a dose of incredible pain make the leaves and stems look deceptively soft and felty, “as if it were a hairy, friendly green plant that you would like to rub,” he said.

If it is not yet clear: Do not do it.


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