First posted on 04-19-2012
When Dr. Doolittle longed to converse with animals, I’m not sure he had worms in mind. But a team of California Institute of Technology scientists got down in the dirt to discover a communication technique used by nematodes, one of the most abundant animals on Earth.
Scientists already discovered that many other animals display means of communicating within their species—whales and dolphins produce high-pitched signals, ants leave scent trails for other ants to follow, birds use color to signal a mate or show anger. Until now, little was know about how nematodes communicate.
Nematodes are microscopic roundworms with species that live in the soil, in marine environments or in fresh water. They’ve adapted to frigid artic ice, the pressure of deep-sea sediment, and to hot springs. Most are beneficial to maintaining the health of their environments, but some are destructive to plant roots and tissues, and a few even present diseases to animals, including humans.
While previous research showed that one type of nematode, Caenorhabditis elegans, uses chemical signals to trade information, the unknown was whether other nematodes used similar means of talking shop.
When researchers examined a variety of nematode species, they found the same set of chemical signals being combined and used to communicate. “It really does look like we’ve stumbled upon the letters or words of a universal nematode language, the syntax of which we don’t yet fully understand,” said Paul Sternberg, the study’s lead author.
“We can now say that many—maybe all—nematodes are communicating by secreting small molecules to build chemical structures called ascarosides,” says Sternberg. “It’s really exciting and a big breakthrough that tells us what to look for and how we, too, might be able to communicate with this entire phylum of animals.”
Andrea Choe, a graduate student at the time, assisted Sternberg with his research. “I turned a section of Paul’s lab into a parasite zoo, and people were both intrigued by it and terrified to come back there,” she said. “One day they would see me cutting carrots to culture plant parasites, and the next I would be infecting mosquitoes or harvesting hookworms from rat intestines. We really tried to get as many different samples as we could.”
After cultivating a wide range of different nematode species, the team bathed the creatures in what they called “worm water,” which collected the chemicals emitted by each nematode. They filtered out the worms and waited for lab results.
“When the results came back from [the lab], showing that the same ascarosides were present in all the worm-water samples, I thought that they had made a mistake,” says Choe. “It was a very surprising finding.”
The next logical step is to learn more about how the worms sense the presence of ascarosides.
“Now that we know these chemicals are broadly present in nematodes, we want to find the genes that are responsible for the ability to respond to these chemicals,” says Sternberg. “That knowledge could open up a whole other angle, not just for dealing with the chemicals, but for actually interfering with those communication systems a little downstream by hitting the receivers.”
The team is also working on further deconstruction of nematode language. Sternberg wonders what comprises the chemical combination necessary to say “food,” or “attack.” The plan is to find ways to interrupt communications between destructive nematode species, which could lead to the eradication of plant pests and animal parasites.
Photo: Many different species of nematodes were found by the Sternberg lab to communicate using the same types of chemical cues. Photo credit: California Institute of Technology
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