Mosquitoes have a neural system to always smell humans

08/28/2022 at 08:07

EST

Even cutting off their antennae receptors they still smell people

When the mosquitoes female looking for a human to bite him, they smell a unique cocktail of body odors that we emit into the air. These odors then stimulate receptors on the mosquitoes’ antennae. Scientists have tried to remove these receptors to try to make humans undetectable to mosquitoes.

Nevertheless, even after removing an entire set of odor-sensitive receptors from the mosquito genome, mosquitoes still find a way to bite us. Now, a group of researchers, who published in the journal Cell on August 18, found that mosquitoes have developed redundant safety devices in their olfactory system that ensure they can always smell our scents.

“Mosquitoes are breaking all our rules about how animals smell things“, explained Margo Herre, a scientist at Rockefeller University and one of the main authors of the article.

In most animals, an olfactory neuron is only responsible for detecting one type of smell. “If you’re a human being and you lose a single odor receptor, all the neurons that express that receptor will lose the ability to smell that odor,” says Leslie Vosshall, a Howard Hughes Medical Institute professor at Rockefeller University and the lead author of the study. Article. But she and her colleagues discovered that this is not the case for mosquitoes.

A mosquito biting a person | pixabay

“You need to work harder to kill mosquitoes because getting rid of just one receptor doesn’t have any effect,” Vosshall points out. “Any future attempts to control mosquitoes with repellants or anything else must take into account how unbreakable their attraction to us is.”

“This project started out of the blue when we were looking at how human scent was encoded in the mosquito brain,” says Meg Younger, a professor at Boston University and one of the paper’s lead authors.

a complex mechanism

They found that neurons stimulated by the human odor 1-octen-3-ol are also stimulated by amines, another type of chemical that mosquitoes use to seek out humans. This is somewhat unusual, since according to all the existing rules for how animals smell, neurons encode odor with narrow specificity, suggesting that 1-octen-3-ol neurons should not detect amines.

“Surprisingly, neurons for human sensing via 1-octen-3-ol and amine receptors were not separate populations,” says Younger. This can allow all human-related odors activate the “human sensing part” of the mosquito’s brain, even if some of the receptors are lost, acting as a safety mechanism.

The team also used single-core RNA sequencing to see what other receptors individual mosquito olfactory neurons are expressing. “The result gave us a broad view of how common receptor co-expression is in mosquitoes,” according to Olivia Goldman, another lead author on the paper.

Vosshall believes that other insects may have a similar mechanism.. Christopher Potter’s research group at Johns Hopkins University recently reported that fruit flies have a similar co-expression of receptors on their neurons. “This may be a general strategy for insects that rely heavily on their sense of smell,” says Vosshall.

In the future, Meg Younger’s group plans to discover the functional significance of the co-expression of different types of olfactory receptors.

Reference study: https://www.cell.com/cell/fulltext/S0092-8674(22)00927-8?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0092867422009278%3Fshowall%3Dtrue

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