Spider and centipede venom contain a terrifying cocktail of chemicals that are used to devour prey and defend themselves from predators. Some, like the funnel-web spider's venom, are able to instantly paralyze its victims. Now, a new study has revealed the origin of their venom, and oddly enough, not only did this powerful weapon evolve from insulin-like hormones, but this evolution occurred in arachnids as well as centipedes.
Researchers first looked for similarities between the proteins in the venom and other molecules in hormones. After analyzing these protein sequences, researchers were unable to find any genetic similarities, but did discover that they had similar molecular shapes.
"If you take the sequence of the spider toxin and you do a BLAST search, the hormone is so different now that you don't pull it out," said study senior author Glenn King, from University of Queensland's Institute for Molecular Bioscience, in a statement. "But when we did a structural search and it pulled up the hormone, that's what really surprised us—the sequence didn't tell us where the toxins evolved from, but the structure did pretty clearly."
The venoms evolved from a hormone that once helped regulate sugar, similar to what insulin does for humans. Venoms aren’t all bad as they can provide researchers with the opportunity to study different chemicals, and these natural resources can be broken down. By getting a clearer picture of the origin and structure of these venoms, researchers hope to develop new pharmaceuticals and bioinsecticides by altering their chemical structure. Some of these products include analgesics and blood pressure drugs.
Centipede venom was found to be the most stable as it underwent more subtle changes. Researchers hope to remove the toxicity in the venom, and use it as an engineering template to find a solution for agricultural or medical problems. Though researchers aren’t clear how exactly this hormone evolved to be a powerful weapon for centipedes and spiders, King speculates that: “If a hormone does something bad to prey, you might recruit it into the venom and make lots of it. That's the starting point and it can then evolve to become more potent.”