Technology: Convert female mosquitoes that affect mosquito control to unbited males

Researchers at the Virginia Institute of Technology have shown that a single gene can convert female Aedes aegypti into fertile male mosquitoes and identified genes required for male mosquito flight.

Male mosquitoes do not bite and cannot infect people with pathogenic bacteria. On the other hand, female mosquitoes can bite.

Female Aedes aegypti requires blood to make eggs and is a major carrier of the pathogens that cause zika and dengue in humans.

“The presence of the male-determining locus (the M locus) establishes male sex in Aedes aegypti, and the M locus is inherited only by male progeny, like the human Y chromosome,” Department Zhijian Tu, a professor of the Department, said. Biochemistry of the Faculty of Agriculture and Life Sciences.

“By inserting Nix, a gene that determines men at the M locus of Aedes aegypti previously discovered, into a chromosomal region that can be inherited by women, it is possible to transform women into fertile men with Nix alone. This has the potential to impact future mosquito control technology development.”

These findings are Minutes of the National Academy of Sciences..

“We also discovered that a second gene, called myo-sex, is required for male flight. This study sheds light on the molecular basis of function at the M locus, which contains at least 30 genes. “Azadeh Aryan, a researcher at the Tu lab and the first author of the paper, said.

Aryan et al. generated and characterized multiple transgenic mosquito lines expressing extra copies of the Nix gene under the control of their promoters. Maria Sharahova, an associate professor of entomology at the University of Agricultural and Life Sciences, and Anastasia Naumenco, a former graduate research assistant, have mapped extra-chromosomal insertion sites in Nix.

The Virginia Tech team worked with Zack Adelman’s lab at the Entomology Department of Texas A & M University and the University of Virginia’s Biocomplexity Institute & Initiative’s Chunhong Mao to help Nix transgene without the M locus. Has been found to be sufficient to convert women into men with male-specific sexually dimorphic traits and male-like gene expression.

“We found that sex change through Nix was permeable and stable across many generations of the lab, which means that these traits will be passed on to future generations. He is a former member of the Adelman and Tu labs and is currently a senior researcher at the Pilbright Institute in the United Kingdom.

The Nix gene was able to convert a woman into a man, but the converted man could not fly because it did not inherit the myo-sex gene at the M locus.

Knocking out the muscularity of wild-type males confirmed that the lack of muscularity in transsexual males was the reason they were unable to fly. Mating requires a flight, but transsexual males were able to father viable transsexual offspring even when presented with cold anesthetized wild-type females.

“Nix has great potential to develop mosquito control strategies that support sterile insect technology that needs to reduce the number of vectors through the mosquito-to-female sex change or release only non-bite men. “, said Tu research scientist James Biedler.

Genetic methods that rely on mating to control mosquitoes target only one particular species. In this case, the Tu team is targeting Aedes aegypti, a species that threatens humans by invading the Americas hundreds of years ago.

However, further investigation is needed before creating useful transgenic lines for initial testing in laboratory cages. “One of the challenges is to create a transgenic line that transforms females into fertile flying male mosquitoes by inserting both the Nix and myo-sex genes together into the genome.” Said Adelman.

The Tu team looks forward to exploring the mechanisms by which the Nix gene activates the male developmental pathway in the near future. The team is also interested in how it evolves within the same mosquito species.

“We found that the Nix gene also exists in other Aedes aegypti. The question is how this gene and the sex-determining locus evolved in mosquitoes.” Tu, a faculty member of the Fralin Life Sciences Institute Said.

In addition to jumping deep into the mosquito’s Nix gene, researchers hope these findings will help further investigation of homomorphic chromosomes found in other insects, vertebrates, and plants.

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Yumin Qi, a Virginia Tech researcher, and Justin Overcash, a former graduate student at both the Virginia Tech and the Texas A&M University, also contributed to the study.

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