But not everyone knows that you will get anything from the trees.
Our research on the venom of Australian stinging trees found in the north-east of the country suggests that these dangerous plants may inject scorpion wanderers with chemicals, such as those found in stings of scorpions, spiders and cone snails Going
A handful of nettle trees are so poisonous in the jungles of eastern Australia that such signs are usually planted where humans pass through their habitat. These trees are called Gimpi-Gimpi in the language of the indigenous Gubbi Gubbi people, and Dendrocnide Botanical in Latin (meaning “tree stinger”).
An accidental split-touch touch on the hand by a leaf or stem is enough to induce pain for hours or days. In some cases the pain has been reported to last for weeks.
A gympai-gympipe sting feels like a fire at first, then reminds of the affected body part being caught in a slammed car door. There is a final stage called allodynia for the days following the sting, during which an unpleasant activity such as taking a shower or scratching the affected skin controls the pain.
How do trees cause pain?
Pain is an important feeling that tells us that something is wrong or something should be avoided. Pain also creates a heavy health burden with serious effects on our quality of life and economy, including secondary issues such as the opium crisis.
To control pain better, we need to understand it better. One way is to study new methods to induce pain, which we wanted to accomplish by better defining the pain-free mechanisms of the GIMP-GIMP trees.
How do these plants cause pain? It turns out that they are generally significantly less common with poisonous animals.
The plant is covered in hollow, needle-like hairs called trichomes, which are reinforced with silica. Like common nets, these hairs contain toxins, but they must have some excess to cause so much pain.
Earlier research on species Dendrocyanide moides A molecule called Moroidin was identified that was thought to cause pain. However, experiments to inject human subjects with Moroidin failed to induce a different series of painful symptoms than those seen with Purna. Dendrocnide Sting.
The culprits are being searched
We studied the stinging hair of the huge Australian stinging tree, Dendroconide excelsa. Taking extracts from these hairs, we separated them into their individual molecular components.
One of these different fractions received significant pain reactions when tested in the laboratory. We found that it contains a small family of related mini-proteins that are significantly larger in size than moroidin.
We then analyzed all genes expressed in GIMP-GIMP leaves to see which gene could produce something with the size and fingerprint of our mystery toxin. Consequently, we discovered molecules that could reproduce the pain response even when artificially created in the laboratory and implanted in isolation.
Genome of Dendrocyanide moides Similar genes encoding toxins were also detected. In Dendrocnide The peptides are named Gympitide.
Gympitides have a complex three-dimensional structure that is held constant by a network of links within the molecule that is of a knotted shape. This makes it highly stable, meaning that it remains intact for a long time after being injected into the prey. In fact, there are also reports of 100-year-old stinging tree specimens housed in the herbarium, yet can cause painful stings.
What was surprising was that the 3D structure of these gympitoids resembles the size of the well-studied toxins from spider and cone snail venom. This was a big clue as to how these toxins might work, as similar toxic peptides from scorpions, spiders, and conifer snails are known to affect structures called ion channels in nerve cells, which are important mediators of pain.
In particular, gympitoids interfere with an important pathway for the operation of pain signals in the body, called voltage-gated sodium channels. In a cell affected by gympitoids, these channels are not normally closed, meaning that the cell has difficulty closing the pain signal.
Better understanding can bring new treatments
The Australian stinging tree forms a neurotoxin that resembles a toxin in both its molecular structure and how it is deployed by injection. Taking both of these things together, it appears that two different developmental processes have transformed into similar solutions to win the endgame of reducing pain.
In the process, evolution has also given us an invaluable tool to understand how pain occurs. The exact mechanism by which gympitides affect ion channels and nerve cells is currently under investigation. During that investigation, we may find new avenues to bring pain under control.
Irina Waiter is a A future fellow of the Australian Research Council at the University of Queensland, Edward Kalani Gilding is a postdoctoral research officer at the University of Queensland, and Thomas Durek a senior research fellow at the University of Queensland