Did you know that only female mosquitoes bite? This is because they require blood to sustain developing eggs. By turning female mosquitoes into males then, researchers are hoping to put a stop to, if not at least lessen, cases of mosquito-transmitted diseases.
To do this, researchers identified a gene found to be responsible for determining sexes in mosquitoes capable of transmitting chikungunya, dengue and yellow fever viruses. In a study published in the journal Science Express, they detailed how a genetic switch known as Nix controls the differences that determine males and females in Aedes aegypti mosquitoes. Considered as a master switch, Nix is typically found in genomic black soles so it's been hard to spot it in insects before.
"Nix provides us with exciting opportunities to harness mosquito sex in the fight against infectious diseases because maleness is the ultimate disease-refractory trait," explained Zhijian Jake Tu, an affiliate of the Fralin Life Science Institute and a biochemistry professor from Virginia Tech's College of Agriculture and Life Sciences.
For the study, the researchers injected mosquito embryos with shots of Nix. Results showed that over two-thirds of female mosquitoes grew to develop male genitals. When Nix was removed with CRISPR-Cas9, a genome-editing method, male mosquitoes, in turn, developed female genitals.
The study lays down the groundwork for developing strategies to control mosquito numbers by changing females into harmless men or at least selectively getting rid of deadly females. However, Zach Adelman, an entomology associate professor from the College of Agriculture and Life Sciences, said that research is still not quite there yet as the ultimate goal is to establish transgenic lines capable of expressing Nix in genetic females so they can be converted into males.
Aedes aegypti originated in Africa and started to gain a foothold in the United States after arriving by ship in the 1700s. This mosquito species is highly problematic as it can quickly adapt to human environments, transmitting pathogens to people easily. For their high effect on the human population, the Aedes aegypti actually belongs to a small portion of mosquito species capable of transmitting diseases to humans.
Changing the gender of Aedes aegypti mosquitoes in areas they are non-natives should not have a lot of environmental impact but will have a drastic effect on human health, added Brantley Hall, co-first author for the study.
Other authors include: Sanjay Basu, Xiaofang Jiang, Yumin Qi, Vladimir Timoshevskiy, James Biedler, Maria Sharakhova, Rubayet Elahi, Michelle Anderson, Xiao-Guang Chen and Igor Sharakhov.