▎ WuXi AppTec content team editor
As soon as the summer is over, the summer officially begins. And mosquitoes, one of the creatures humans hate the most, are ready to start looking for this year's prey.
When a group of people sit together, there is always a mosquito pet who will be born. When the lucky one turns out to be yourself, you will definitely think: Why do you just stare at me and bite? Or can you not bite people, let the family's wealth and Mimi sacrifice to be bitten...
Image credit: 123RF
What we may not know is that many mosquitoes do not necessarily have to catch humans, but will pounce on them when there is a nearby blood source. But our most hated "flower mosquito," the Aedes aegypti, has gone a different way and has evolved into a species that specializes in biting humans.
By what exactly do they pinpoint humans? New research from Nature has found that this may be related to the special odor molecules in humans.
Human odors are made up of dozens of different compounds, while the types of compounds in other mammalian odors may not vary much, but the proportions of the various molecules vary. It is a truth that the proportion of various spices in cooking is different, and the aroma is different. These compound ratios also create a special smell for humans.
But how did the Aedes aegypti mosquito identify the particular molecules? The first thing scientists do is collect different odors for analysis and test how Aedes aegypti responds to them.
This is also the most interesting part of the study, the researchers collected a total of human, rat, guinea pig, quail, sheep and dog scents, most of the animal odors from their hair, such as wool donated from farms, dog hair cut from pet hospitals... Scientists may have to place their hands in the system themselves to attract mosquitoes.
According to zhao Zhilei, the first author of the study and a postdoctoral fellow in neurobiology at Cornell University, the researchers found that even the smell of human daily conditions is enough to have enough attraction to Aedes aegypti mosquitoes, and mosquitoes are obviously more interested in human taste.
▲ With the help of a special wind tunnel device, the hair of various animals and the odor emitted by human samples were delivered to mosquitoes (Image source: Reference[2])
And when they wanted to further analyze which compounds in human odor played a role, the "sacrifice" made by the researchers was even greater. The researchers took a few days without bathing, then stripped naked and lay down in a Teflon bag to collect the scents.
Dr. Zhao Zhilei explained: "In this way, the odor concentration is relatively high, and we can collect a large amount of odor for experiments in a short period of time; in addition, artificial fragrance is often added to shampoo shower gel, which may interfere with the experimental results." ”
And because the cotton, polyester or other fibers of the clothes will also produce unique odor molecules, affecting the actual data, this step must be required to be nude.
In addition to collecting and analyzing odors, the team also built special genetically modified mosquitoes whose brains, such as olfactory globules in primary olfactory brain regions, fluoresce when activated, allowing them to see which neurons are activated when they receive odors.
Image credit: 123RF
Subsequently, studies began testing the response of mosquito brains when different compounds were exposed. They had expected that this precise distinction might require the use of the vast majority of olfactory globules, but the results surprised the researchers.
Different odors activate different combinations of olfactory globules. But of the many olfactory globules, only two are involved in the process of screening human odors. No matter how many human or animal samples are used, the result is so simple.
One of the olfactory globules reacts to many odors, including human odors, and can guide mosquitoes in the direction of the odor; the other olfactory globules respond only to humans but weakly to other mammalian odors. Under this combination, mosquitoes will run towards humans without hesitation.
▲ There is a unique olfactory globule that reacts to human odors (Image source: References[2])
This olfactory globule is particularly sensitive to two special molecules, decanal and undecaldehyde. Both molecules are highly enriched in human odors and rarely in mammals. Our sebum and metabolism determine this and make us a target for Aedes aegypti mosquitoes.
By artificially synthesizing a mixture of the two molecules, the mosquitoes will also begin to initiate a host search after being sent to the wind tunnel. Therefore, in theory, if some people have a lot of sunflower and undecylaldehyde in their metabolites, they can easily become targets of mosquitoes.
Dr. Zhao Zhilei said: "The two aldehydes are too little or too much, and mosquitoes don't like it. Therefore, in theory, it is possible to interfere with the bite of mosquitoes by increasing or decreasing the concentration of these two aldehydes in human odor. Of course, there is no mature method to specifically mask these two molecules. ”
But! You can't cover up the smell, you can also set up odor traps to catch mosquitoes, which is likely to bring a new generation of anti-mosquito technology! (Looking forward to ing)
According to Dr. Zhao Zhilei, the study found that a specific proportion of decanal-containing mixtures has a strong attraction to mosquitoes, and the current research team has applied for a patent based on this, mainly using the mixture in mosquito traps to attract and kill mosquitoes. Before it is officially commercialized, field experiments are also needed to test whether it can also attract mosquitoes efficiently in the wild.
If it works, it's like the blue-light flycatcher you usually see in restaurants, and maybe you won't have the trouble of mosquitoes after installing a small device.
Resources:
[1] How mosquito brains encode human odor so they can seek us out. Retrieved May 5th, 2022 from https://www.eurekalert.org/news-releases/951690
More recommendations
Click "Watching" and go again