Scorpion venom can paralyze, inflict pain, even kill. But instead of recoiling in fear from the arachnids, scientists are scrutinizing venom in the hopes of harnessing its power to fight insects, treat cancer and more.
In one approach, Israeli researchers have cloned the genes involved in producing specific toxic protein compounds. They have developed ways to produce and manipulate these toxins inside bacteria grown in their lab. They have also deciphered the three-dimensional structures of some of those compounds and figured out which surface of those structures bind to the nervous systems of insects.
These technical developments may eventually help scientists develop new, scorpion-inspired pesticides that would zero in on specific insect pests without harming people, the environment, or other animal bystanders.
"You should consider scorpions like a gift from nature," said Michael Gurevitz, of Tel Aviv University in Israel. "Nature has developed compounds during millions of years that show complete selectivity to various groups of animals. Understanding how these toxins affect the nervous system of animals may assist in preparing chemicals that mimic the toxin activity and can be produced industrially."
For decades, scientists have been probing the compounds in venom from scorpions, spiders, sea anemones, cone snails and other creatures. Plenty of studies have dissected venom to see what types of proteins are in it, what those proteins look like, and how they work -- by, for example, causing paralysis or breaking down cells.
A major goal has been to spin those findings into practical applications. For example, venom compounds are appealing candidates for pesticides because many of them are highly specialized to kill certain types of insects but have no effect on people, other mammals or beneficial insects, like honeybees.
The toxins that interest researchers are biodegradable, so they would not accumulate in the ground or drinking water, linger on vegetable skins, or endanger our health like modern chemical pesticides do. Translating scientific studies into practical applications, however, has been tough. For one thing, simply spraying venom compounds on crops doesn't do any good, because insects can swallow and digest the proteins in their guts without harm.
In order to kill, venom compounds need to enter an insect's blood, like what happens after a sting. Scientists can't sting individual insects. Finding a good delivery system is what they are struggling with now.
Venom toxins are "a resource with almost limitless potential," said Raymond St. Leger, an entomologist at the University of Maryland, College Park. "But you need a way of getting them into the insect."
Some researchers are experimenting with viruses and fungi as delivery systems. Gurevitz, who has been studying "the pharmaceutical factory in venom glands" for more than 20 years, is taking a different approach.
He is looking at the way these toxins interact with structures called sodium channels, which are located on the membranes of cells in nervous and muscular tissues. Essentially, he is getting at the molecular details of how toxic compounds in venom recognize sodium channels, bind to them, and then cause paralysis and death.
First, the scientists had to develop ways of producing the toxins and their target channels in the lab. To do that, they cloned related genes and established systems for expressing and mutating both the toxins and the channels they bind to.
Using bacteria, Gurevitz and colleagues are now producing their own venom compounds and manipulating their shapes to see what they do. Down the line, they aim to develop safe and powerful pesticides. They also hope that the knowledge they're acquiring will pave the way for production of chemicals that would mimic the toxins and be just as selective about which insects they kill.
"As we know more details about how these toxins bind and affect the sodium channels, we would be able to engineer toxins" and develop chemical mimics that would be easier for industry to produce, Gurevitz said.
These developments are not imminent, he said, but they are possible. Some drugs already fit the description, including one that was derived from cone snail venom and my help fight chronic pain.
Adding an effective and environmentally friendly battery of pesticides would be highly valuable, St. Leger said. Insects are incredibly good at developing resistance to the chemicals we thrown at them. The more options we have, the better
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