Researchers map mosquito cells that may help the insects choose tastiest humans
In a bid to understand why mosquitoes may be more attracted to one human than another, Johns Hopkins Medicine researchers say they have mapped specialized receptors on the insects’ nerve cells that are able to fine-tune their ability to detect particularly “welcoming” odors in human skin.
In a report published in the Feb. 28 issue of Cell Reports, the researchers described their search for the receptors in segmented tube-like antennae of 10 female and 10 male mosquitoes.
Bites to human skin come from female mosquitoes, although some research indicates that males are also attracted to human odors.
To find neurons expressing ionotropic receptors in the antennae, the researchers used a technique called fluorescent in situ hybridization, which pinpoints not the receptors themselves, but genetic material called RNA, a cousin of DNA. Finding RNA linked to ionotropic receptors means that the neurons are highly likely to be producing such receptors.
The scientists thought they’d find similar numbers of ionotropic receptor-laden neurons in each of the antennae segments, but they found the majority of ionotropic receptors in the distal (farthest from the head) part of the antennae.
They also found, however, that the antennae had more ionotropic receptors in the proximal (near the head) part of the mosquitoes.
In the current study, the researchers were able to identify some pairings of receptors that predicted if an ionotropic receptor would respond to acids or amines. They verified these predictions by using genetic engineering to visualize the responses of an ionotropic receptor called Ir41c in the mosquito. Ir41c-expressing neurons were activated by one type of amine as predicted, but were inhibited (turned off) by a different type of amine.