this aedes aegyptiKnown as dengue fever or yellow fever, the mosquito is one of the most dangerous to humans, as it is a carrier of these and many other diseases. These mosquitoes have a relentless system of detecting their prey. Now we’re starting to learn how they do it.

A guided pecking.
We know that scent is key for mosquitoes to find and select their victims (although it’s not the only resource they have). The carbon dioxide we release when we breathe is one of the chemicals these animals sense, as well as some of the chemicals that come from our sweat, such as octenol or some aldehydes.

this aedes aegypti it is also a particular aggressor: it feeds on blood only when human (keeping in mind that only female mosquitoes bite when they need protein for their eggs) and avoids biting other animals, not even other mammals. A new study examines how this “unbreakable attraction” to people can overcome even the barriers we try to put as many barriers as possible.

Special fragrance.
The neurons of these mosquitoes, despite not having a central nervous system, thwarted the scientists’ plans. And it was because of the receptors dedicated to smell that the neurons of these animals have.

A study recently published in the journal Cell showed that the smell of mosquitoes was very different from what was thought. In their study, the team found that each of the neurons in the mosquito’s olfactory system can detect various chemical compounds.

You deserve a Nobel prize.
The scientific consensus was established by a group of researchers who studied mice and discovered that the olfactory system was highly specialized. Each olfactory neuron expresses a specific receptor for a particular type of odor that communicates with a group of nerve endings called the glomerulus.

For example, this specialization that does not occur in the sense of taste would make evolutionary sense. According to Margaret Herre, first author of the paper, this will “give animals the ability to live in a rich olfactory field, to perceive and distinguish a wide variety of odors.”

Thanks to this research, Leslie Vosshall worked in the laboratory of Richard Axel, one of the scientists who won the Nobel Prize in 2004. He is now one of the researchers who put a big “but” in his research by discovering the ability of mosquito neurons to detect various odors.

Excess.
For the team, this nuanced consensus was surprising. Vosshall explained that each cell seems to express everything in a so-called hyper-specialized system. At first glance, nothing seemed logical.

Having this redundancy in neurons gives mosquitoes a huge advantage over the tricks humans use to escape their bites. It only blocks a bunch of chemicals, making it harder for us to sneak around.

“The way the Moquito regulates his sense of smell is completely unexpected,” Vosshall says in one of the published press releases. “But for the mosquito it makes a lot of sense. Every neuron that interprets odors is so redundant that the olfactory system is essentially unbreakable. This may explain why we haven’t found a way to overcome mosquitoes’ attraction to humans.”

genetic editing.
The discovery came while the team was analyzing the response of mosquito neurons to carbon dioxide. Using the CRISPR gene-editing tool, they added a fluorescent protein to neurons with CO2 receptors and another protein to neurons responsible for responding to chemicals in our body odor. So they discovered that the same neurons can be activated by different scents. This could not be.

The results of the first analysis surprised the team so much that they used different methodologies to validate it. One of these methodologies was single-core RNA sequencing (snRNA-seq), which confirmed the results. A new system using electrodes to analyze the mosquito’s olfactory system also helped confirm the results.

The fruit fly is another exception.
But perhaps the experiment with the greatest validation value came from another team and another animal: the fruit fly. Christopher Potter of Johns Hopkins University found that the fruit fly (an animal that, incidentally, was also studied by Vosshall years ago) has a similar olfactory system.

Better repellents and techniques to prevent their bites.
This finding doesn’t tell us how to combat the bites of this dangerous insect, but it at least tells us what we’re doing wrong. Camouflaging a particular scent doesn’t work well when the animal can easily detect us using another scent. Perhaps the answer lies in other tactics, such as overloading the mosquito’s olfactory system or using traps to deflect them. Or more radical ones.

Still the way to go.
The team agreed that there is still a long way to go. One of its next goals will be to compare whether the olfactory systems of other mosquitoes, particularly those that do not include blood in their diet, exhibit the same mechanism.

The team also wants to know exactly how the combination of scents creates a kind of multiplier effect in the mosquito brain, where when you add the scent of the carbon dioxide we emit, the whole is greater than the sum of the parts. . with chemical compounds formed in our skin.

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