Section: Features

Kenyon labs researching alternative pesticide mechanisms

Kenyon labs researching alternative pesticide mechanisms

Gambier in April may not be home to many mosquitoes, but Higley and Tomsich Halls are a different story.

Professor of Biology Chris Gillen and Visiting Assistant Professor of Chemistry Matt Rouhier study the mosquito Aedes aegypti in their labs alongside student researchers. Both scientists hope to shape the world’s approach to mosquito-borne diseases, but they emphasize the incremental nature of that work. Since many mosquitoes have built up resistance to the insecticides used to kill them, Gillen and Rouhier expressed the need to find alternative biological mechanisms to eliminate the insects.

Rouhier’s lab looks at xenobiotic transporters, which transport foreign molecules out of a mosquito’s body. These transporters are particularly important during the “blood meal,” which is an exclusively female act for the species. The females consume blood because they must lay their eggs. But whatever is in a person’s bloodstream enters the mosquito during this blood meal; if the person took ibuprofen, Rouhier said, the mosquito is now taking ibuprofen. The xenobiotic transporters in the kidney then filter out these toxins.

“[The mosquito’s] kidneys are incredible, but like all sort of animal superpowers, they’re also its weakness,” Rouhier said.

He explained that since the 1970s, the primary class of pesticides    called pyrethroids — used to kill mosquitoes has targeted their nervous system. But because this method has been so ubiquitous, many mosquitoes have built up resistance to it. Looking at these transporters in the kidneys, as Rouhier does in his lab, is a potential route for future pesticides.

“If we can then learn about these xenobiotic transporters, can we cause them to malfunction?” Rouhier asked. “And as a result, we’ve given the mosquito kidney failure.”

Gillen’s lab analyzes transporters that carry salt across membranes in mosquitoes, and how that compares to similar transporters in vertebrates. During his postdoctoral training, he worked with mammalian transporters. He described his initial approach to the insect versions when he came to Kenyon as “hopelessly naive”: he assumed that these versions would be predictable based on the mammalian ones, with some interesting differences.

“We sort of figured what we would find in the mosquito lines or some other things would be just versions of [the vertebrates’],” he said. “But turns out that looks completely wrong at this point.”

He described how qualitatively different these transport systems are in insects, and how exciting this complexity is for himself and the scientific community. But this also presents a challenge. Many scientists in his field know how to characterize these transporters in mammals — but have much more difficulty doing so in insects.

“It’s really challenging us now to come up with ways to functionally characterize these,” he said. During our interview, he pointed to the name of an insect transporter protein on his computer screen, dramatically whispering, “I have no idea what that is.” He added that he could make some guesses, and that it probably transports sodium and chloride, but his usual tools to determine its function might not work.

Gillen said that far in the future, the work his lab is doing could help to determine an inhibitor for these transporters and then a new type of mosquitocide. Salt transporters are particularly important for the mosquito during blood meals because the insect has to fly away after taking blood. How do they quickly get rid of all that fluid? They pee.

“They’re champion urinators, basically,” Gillen said.


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