Better living from scorpion venom

Toxins in venom could be used to battle pests, fight cancer, even numb pain

When a scorpion attacks, its victim rarely has time to fight back. First, the clawed creature grabs and pins down its target — maybe a cricket, grasshopper or spider. Using a stinger in its rear end, the scorpion jabs the victim’s flesh. Then, the true suffering begins.

After an initial shock of severe pain, the prey might start to feel burning and tingling sensations. Shaking and trembling ensue, followed by paralysis. If the victim doesn’t die from the venom, the scorpion will probably just eat it alive.

The venom in one scorpion can contain hundreds of different toxins. The deadly African fat-tailed scorpion (Parabuthus transvaalicus) has a toxin that can kill one type of beetle but not another. This variety and specificity could make scorpion venom a good source of natural pesticides.
Alexander Tietz /Wikimedia Commons (CC BY-SA 2.0 de)

Even people can die from the sting some scorpions deliver. But despite the fear that scorpions inspire among many people, scientists refuse to run away or even fight back. Instead, they are drawing inspiration from scorpions and other stinging animals. In the safety of their laboratories, researchers are squeezing venom out of poisonous creatures. They are dissecting the venom, decoding its secrets, and making chemical versions of their own.

This is what venom researchers know: Understanding an attacker is the best way to steal its powers. With a growing list of discoveries, scientists are developing scorpion-inspired pesticides, cancer treatments, painkillers and more.

“Look at the world from the viewpoint of a scorpion,” says Raymond John St. Leger, an entomologist (insect expert) at the University of Maryland in College Park. “It wants toxins which can kill insects so it can eat those insects. Then it wants toxins for defense. In the case of something big and nasty like a child that comes to stomp on it, it wants to be able to defend itself. There are a lot of different chemicals there.”

Tapping into those chemicals, experts say, has enormous potential.

“This is one of the major resources that is naturally available to us,” St. Leger says. “It looks like [venom has] a very bright future, much of which we can’t predict.”

A world of venom

Many animals ― spiders, snakes, bees, stingrays, centipedes, anemones, ants and snails, to name some ― make venom. Compared with the venom from other animals, scorpion venom is one of the simplest types to study. It looks like a thick milky soup, and is made of a variety of molecules, including hundreds of small proteins called peptides.

Many of those peptides are toxic. That means that they have the power to harm the cells of unfortunate victims. They might cause paralysis, for example. Or they might kill cells. Venom toxins have to get inside cells to cause damage. There, they work in different ways to destroy cells or change the messages cells send to other cells.

To extract venom from a scorpion, scientists often use a long tool to hold the animal at a distance. A mild electric shock then causes the animal to squirt a little venom, which the scientists collect in a little test tube.

Venom expert Bora Inceoglu once studied a type of scorpion that was so aggressive, all Inceoglu had to do was grab the scorpion and the animal would squeeze out some venom. For protection, Inceoglu, who works at the University of California, Davis, wears only a pair of goggles. He doesn’t worry too much, because venom is harmless if it gets on your skin. He has never been stung.

“Initially, I was nervous, but then I got used to it,” he says. “My wife was with me one time, and she got so scared she had to leave the room.”

A typical squirt holds between 5 microliters and 50 microliters of liquid. One microliter is a millionth of a liter, and 50 microliters is the size of a really tiny droplet. A whole lot of toxic peptides can fit into even just a tiny amount of venom.

Once researchers have extracted venom, the real (and less scary) work begins. Using basic scientific techniques, scientists can pull peptides apart within the droplets collected. Then researchers look at the peptides and test them on animals. The goal is to understand what the peptides look like, how they differ from each other and what they do.

The research involves plenty of challenges. There are 1,300 scorpion species, and as many as 300 peptides in the venom of each one. Most of the peptides scientists know about so far are from one species.

Inceoglu estimates that there are probably more than 100,000 different peptides in the world’s scorpions. So far, scientists have identified about 500 of them. That’s just half a percent of the total that exist.

“That number is increasing,” Inceoglu says. “But we’re nowhere near the whole number.”

Putting toxins to work

As some scientists continue to identify and examine individual toxic peptides inside of venom, others are searching for ways to use those toxins to make the world better.

In one of the most promising approaches, venom toxins are inspiring pesticides that protect agricultural crops from insects. Scorpions are already really good at killing insects, after all. Why not copy what they do?

As an insect-fighter, venom has lots of potential. One reason is that each toxic peptide inside venom has had millions of years to target a specific type of insect. For example, some fat-tailed scorpions in Africa produce a well-studied toxic compound called AaIT. The toxin paralyzes some types of beetles but does nothing to others. It has no effect on humans. Other types of toxins might work only on grasshoppers or locusts. (The number and type of toxins determines how dangerous an animals’ venom is).

That kind of focused attack would be hugely helpful to farmers. Traditional pesticides are made from strong chemicals that tend to harm all animals equally. As these chemicals fight the bad guys, they also hurt the good guys, such as helpful insect pollinators, innocent farm animals like cows, and people. It would be more useful to have venom-like strategies that killed only mosquitoes that carry diseases or worms that eat corn crops.

Scorpion-inspired pesticides would also be safer and more environmentally friendly than chemicals because they would decompose. So, these pesticides wouldn’t build up in soil or water. They can’t get into the bodies of animals and people if they don’t get into water or food.

Scientists have already deciphered what some of these specific toxins look like and how they work. Researchers have even created versions that act like the originals.

The biggest challenge now is to make the venom-inspired pesticides do what they’re supposed to do. Spraying them onto plants won’t do: Insects can swallow venom without harm. Instead, researchers are experimenting with bacteria and fungi that can deliver toxins directly into the bodies of insects, just like scorpion stings do.

“They’ve got great potential,” St. Leger says. “What we need now is delivery systems.”

Healing powers

As crazy as it may sound, venom toxins might also help heal people.

Some scorpion venom toxins affect only the cells of mammals. These compounds probably provide defense against predators, such as coyotes and squirrels. But they also work on humans. That’s bad news if the venom comes from the stinger of a scorpion. In the hands of a doctor, though, the poisons might do good.

Toxic compounds that kill cells, for example, could be injected into tumors to fight cancer. Compounds that paralyze cells could fight pain. In fact, there is already a pain-killing drug available that was inspired by the venomous cone snail, a type of sea snail.

Nature has been doing experiments for hundreds of millions of years, St. Leger says. Some species and strategies have gone extinct. Others, like scorpions, have developed powerful chemicals for staying alive. As venom research pushes forward, there is a lot to be learned from what already exists in the environment.

“All we are left with is all of Nature’s successful experiments,” St. Leger says. “They teach us a lesson. They might show us that things we hadn’t thought of before are possible.”

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