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"The noise encourages the joy and darkness, the ignorant do not distinguish between the listeners and the confused, the dew drops and the moon rises to the sky, and the profit welcomes people.
" The Tang Dynasty poet Liu Yuxi recorded his suffering from mosquito bites in "Polymosquito Ballads
".
In the hot summer, even if it is tightly wrapped, it is always chased by mosquitoes
.
Among mosquitoes, Aedes aegypti mosquitoes have a strong sense of humans, and can locate the location
of humans through the carbon dioxide, body temperature or skin odor exhaled by humans.
And studies have found that Aedes aegypti seems to be easier to target some populations, but the mechanism remains unclear
.
One of the more accepted explanations is that the unique microbiota in human skin leads to differences
in skin odors produced by different people.
However, the smell of human skin is a mixture of a variety of organic compounds, and due to the lack of a complete metabolomics of human skin compounds, little is known about the organic compounds that make up skin odor, and it is not clear whether mosquitoes like to bite specific groups of people because mosquito repellent odors are released too little, or mosquito sucking odors are released too much
.
On October 27, 2022, the team of Leslie B.
Vosshall from Rockefeller University published a research paper entitled "Differential mosquito attraction to humans is associated with skin-derived carboxylic acid levels" in the international top journal Cell.
It was found that the different attraction of humans to mosquitoes was closely related to the level of carboxylic acid produced by human skin, and people who were highly attracted to mosquitoes had higher expressions of carboxylic acid on their skin
.
1
Different human individuals of mosquitoes show obvious preference
.
Two ventilation ducts are about to be designed, nylon stockings of different subjects are placed upwind, and the volatile odor will follow the wind direction to the mosquito gathering place, if the mosquito likes the smell, it needs to fly nearly 1 meter upwind to reach the upwind outlet
.
The experiment found that there was no difference in the attraction of the left and right arms of the same subject to mosquitoes, but there were large differences in the attractiveness of skin odor to mosquitoes in different subjects, among which subject No.
33 showed high attraction to mosquitoes, subject No.
25 showed medium attraction, and subject No.
28 showed low attraction
.
Figure 1: Different human individuals of mosquitoes show obvious preference
2
Mosquito highly attractive people have increased levels of carboxylic acids in the skin odor
Mosquitoes perceive olfactory information through two types of odor-gated ion channels, odor receptors (OR) and ionic receptors (IR).To investigate whether mosquitoes perceive human odor through their sense of smell, the researchers mutated
the co-receptor (Orco) of OR and the co-receptor of IR (Ir8a, Ir76b, and Ir25a), respectively.
After the discovery of the mutant odor receptor Orco gene, mosquitoes could still distinguish between highly attractive and low-attractive people, indicating that the mutated Orco gene did not affect the odor preference of mosquitoes
.
After mutant ionic receptor Ir8a, although mosquitoes can distinguish between highly attractive people and low attraction people, their preference for odor is greatly reduced
.
Mutations Ir76b and Ir25a obtain the same results
as mutations Ir8a.
Figure 2: IR receptors in mutant mosquitoes reduce mosquito preference for human odor
3
Mosquito highly attractive people have increased levels of carboxylic acids in the skin odor
Nylon stocking odor samples were analyzedusing gas chromatography-quadrupole time-of-flight mass spectrometry (GC/QTOF-MS).
Since mutations in IR co-receptors (Ir8a, Ir25a, and Ir76b) lead to a reduced preference in mosquitoes for human odor, while ionic receptors (IRs) respond primarily to acidic compounds, the researchers will focus on detecting acidic compounds
in human odors.
Differential characteristics in human odor samples were analyzed and 9 of the linear fatty acids identified, suggesting higher levels of carboxylic acids
expressed in skin odors in highly attractive populations.
Finally, the highly attractive human odor was analyzed by metabolomics, and it was found that the expression levels of pentadecanoic acid, heptadecanoic acid and nonadecanoic acid increased
significantly.
Figure 3: Increased content of carboxylic acid in the skin odor of highly attractive mosquitoes
summary
In this paper, it was found that mosquitoes have a preference for different human skin odors, and the expression levels of pentadecanoic acid, heptadecanoic acid and nonadecanoic acid in the skin odor of people who are highly attracted to mosquitoes significantly increased, and the above carboxylic acid gas transmits olfactory information through the IR receptors of mosquitoes to locate the location
of humans.
The results of this study provide an effective intervention strategy
for blocking mosquito-borne diseases such as yellow fever, dengue fever and Zika virus.
【References】
1.
https://doi.
org/10.
1038/s41586-022-05328-2
The images in the article are from references
