జAustralia is home to some of the world’s most endangered wildlife. Anyone who spends time outdoors in Eastern Australia is advised to keep an eye out for snakes, spiders, soaring birds, crocodiles, deadly cone snails and small toxic jellyfish.
But what everyone doesn’t know is that you can even get some trees.
Our Research On the venom of Australian sting trees found in the northeast of the country, it is shown that these dangerous plants can inject alert travelers with chemicals such as scorpions, spiders and cone snail bites.
There are some nettle trees in the forests of Eastern Australia, so signs of humans trampling through their habitats are usually kept. These trees are called gimpi-gimpi in the language of the native Gubbi Gubbi people, and Dendrochnide In Botanical Latin (meaning “Tree Stringer”).
A casual split-second touch on the arm through a leaf or stem is sufficient Stimulates pain for hours or days. In some cases the pain has been reported to last for weeks.
A gimp-gimp sting feels like a fire at first, then the pain subsides for hours, reminding you that the affected body part is stuck in the slammed car door. The last stage, called alodinia, occurs a few days after the sting, during which time harmful activities such as bathing or scratching the affected skin recur.
How do trees cause pain?
Pain is an important sensation that tells us something is wrong or something must be avoided. Pain can also create an enormous health burden with serious impacts on our quality of life and economy, including secondary issues such as the opiate crisis.
In order to control pain well, we need to understand it better. One way is to study new ways to induce pain, which we want to achieve by better defining the pain-causing mechanism of gimp-gimp trees.
How do these plants cause pain? They have little in common with poisonous animals.
The plant is covered with hollow, needle-like hairs called trichomes, which are reinforced with silica. Like normal nettles, these hairs contain toxic substances, but they must contain something in addition to provide a lot of pain.
Previous research on species Dendrochloride moroids A molecule called moraidin, which is thought to cause pain, has been identified. However, experiments injecting human subjects with moroidine Failed to trigger A diverse range of painful symptoms that appear in full Dendrochnide Sting.
Finding the culprits
We studied hair pierced from the giant Australian sting tree, Dendrochnide Excelsa. Taking the extract from these hairs, we separated them into their individual molecular parts.
One of these isolated fractions caused significant pain responses when tested in the laboratory. We found that it contained a smaller family of related small proteins in larger quantities than moroidine.
We analyzed all the genes expressed in gimp-gimp leaves to find out the size of our mystery toxin and which gene can produce anything with a fingerprint. As a result, we found molecules that could reproduce the pain response even when artificially made in the laboratory and applied alone.
Gene of Dendrochloride moroids Encoding similar genes has been shown to contain toxins. These are Dendrochnide The peptides were named gimpitides.
Zymphidides have a complex three-dimensional structure that is stabilized by a network of links within the molecule that form the interconnected shape. This makes it very stable, meaning it stays that way for a long time after being injected into the victim. True, there are reports that even 100-year-old tree specimens kept in herbariums can be reported as painful stings.
Surprisingly, the 3D structure of these gimpitides resembles the shape of the well-studied toxins from spider and cone snail venom. Similar venom peptides from scorpions, spiders and cone snails affect structures in nerve cells called ion channels, which are important mediators of pain.
In particular, gimpitides interfere in an important way in maintaining pain signals in the body called voltage-gated sodium ion channels. In a cell affected by gimpitides, these channels usually do not close, which means that it is difficult for the cell to stop the pain signal.
Good understanding brings new therapies
Australian sting trees produce a neurotoxin that resembles a toxin in both its molecular structure and how it is used by injection. When these two things are combined, it seems that two different evolutionary processes have come together on similar solutions to win the painful endgame.
In the process, evolution has also provided an invaluable tool for understanding how pain occurs. The exact mechanisms by which zymphytides affect ion channels and nerve cells are currently under research. In that research, we can find new ways to bring pain under control.
Irina Wetter a Edward Colony Guilding is a future associate of the Australian Research Council at the University of Queensland, postdoctoral research officer at the University of Queensland, and Thomas Durek is a Senior Research Fellow at the University of Queensland