Why mosquitoes can always find us
Mosquitoes recognize (human) odors using scent receptors, which are encoded by certain genes in their DNA. If you disable groups of odor receptors in mosquitoes through genetic modification, they will still recognize people. Researchers have already shown this in the past. A team of scientists from Boston and Rockefeller Universities has now figured out why.
Receptors are chemical structures on the cell membrane or in the cell itself, to which certain molecules – such as odors – can bind. When the right molecule binds to an odorant receptor, that receptor sends a signal to the corresponding neuron. The neurons then pass this signal to the brain. For example, attaching the right odor to odor receptors will cause a signal to be transmitted from neurons to the brain. The brain can then recognize this smell.
The researchers discovered that the neurons responsible for human odor recognition 1-octen-3-ol in mosquitoes are also responsible for recognizing amines. Some amines are also “expelled” into the air by humans. This contrasts with what scientists previously knew about animal scent. Odor receptors in a neuron recognize only one specific odor in most animals.
“If you’re a human and you lose one of your smell receptors, all the neurons connected to that receptor lose the ability to detect that smell,” said Leslie Foshall, one of the study’s authors.
The fact that mosquito neurons can receive signals from different odor receptors ensures that mosquitoes continue to recognize different human-related odors, even if they have lost some of the receptors. The characteristic ensures a pungent sense of smell. “You have to work harder to break the mosquito’s sense of smell. Removing one of the receptors has no effect.
Fossall thinks other insects also use a similar mechanism. “This could be a general strategy for insects that rely heavily on their sense of smell.” Another research group has already reported that some neurons in fruit flies also receive signals from various receptors.
Source: Rockefeller University and Boston University, USA
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