Navigation Links
Genetic engineering alters mosquitoes' sense of smell

In one of the first successful attempts at genetically engineering mosquitoes, Howard Hughes Medical Institute (HHMI) researchers have altered the way the insects respond to odors, including the smell of humans and the insect repellant DEET. The research not only demonstrates that mosquitoes can be genetically manipulated using the latest research techniques, but paves the way to understanding why the insect is so attracted to humans, and how to block that attraction.

"The time has come now to do genetics in these important disease-vector insects. I think our new work is a great example that you can do it," says Leslie Vosshall, an HHMI investigator at Rockefeller University who led the new research, published May 29, 2013 in the journal Nature.

In 2007, scientists announced the completion of the full genome sequence of Aedes aegypti, the mosquito that transmits dengue and yellow fever. A year later, when Vosshall became an HHMI investigator, she shifted the focus of her lab from Drosophila flies to mosquitoes with the specific goal of genetically engineering the insects. Studying mosquitoes appealed to her because of their importance as disease carriers, as well as their unique attraction to humans.

Vosshall's first target: a gene called orco, which her lab had deleted in genetically engineered flies 10 years earlier.

"We knew this gene was important for flies to be able to respond to the odors they respond to," says Vosshall. "And we had some hints that mosquitoes interact with smells in their environment, so it was a good bet that something would interact with orco in mosquitoes."

Vosshall's team turned to a genetic engineering tool called zinc-finger nucleases to specifically mutate the orco gene in Aedes aegypti. They injected the targeted zinc-finger nucleases into mosquito embryos, waited for them to mature, identified mutant individuals, and generated mutant strains that allowed them to study the role of orco in mosquito biology. The engineered mosquitoes showed diminished activity in neurons linked to odor-sensing. Then, behavioral tests revealed more changes.

When given a choice between a human and any other animal, normal Aedes aegypti will reliably buzz toward the human. But the mosquitoes with orco mutations showed reduced preference for the smell of humans over guinea pigs, even in the presence of carbon dioxide, which is thought to help mosquitoes respond to human scent. "By disrupting a single gene, we can fundamentally confuse the mosquito from its task of seeking humans," says Vosshall. But they don't yet know whether the confusion stems from an inability to sense a "bad" smell coming from the guinea pig, a "good" smell from the human, or both.

Next, the team tested whether the mosquitoes with orco mutations responded differently to DEET. When exposed to two human armsone slathered in a solution containing 10 percent DEET, the active ingredient in many bug repellants, and the other untreatedthe mosquitoes flew equally toward both arms, suggesting they couldn't smell the DEET. But once they landed on the arms, they quickly flew away from the DEET-covered one. "This tells us that there are two totally different mechanisms that mosquitoes are using to sense DEET," explains Vosshall. "One is what's happening in the air, and the other only comes into action when the mosquito is touching the skin." Such dual mechanisms had been discussed but had never been shown before.

Vosshall and her collaborators next want to study in more detail how the orco protein interacts with the mosquitoes' odorant receptors to allow the insects to sense smells. "We want to know what it is about these mosquitoes that makes them so specialized for humans," she says. "And if we can also provide insights into how existing repellants are working, then we can start having some ideas about what a next-generation repellant would look like."


Contact: Jim Keeley
Howard Hughes Medical Institute

Related biology news :

1. U of A medical researchers ID genetic marker for sporadic breast cancer
2. Family studies suggest rare genetic mutations team up to cause schizophrenia
3. Fast new, 1-step genetic engineering technology
4. Genetic predictors of postpartum depression uncovered by Hopkins researchers
5. Genetic risk for schizophrenia is connected to reduced IQ
6. European Society of Human Genetics urges caution over use of new genetic sequencing techniques
7. University of Maryland Medical Center launches genetic-testing program for cardiac patients
8. Penn Medicine researchers identify 4 new genetic risk factors for testicular cancer
9. Fred Hutch evolutionary geneticist Harmit Malik selected as an HHMI investigator
10. Genetic and clinical factors best to predict late recurrence in estrogen receptor POS breast cancer
11. Study examines effects of genetic variants for infants with neonatal abstinence syndrome
Post Your Comments:
(Date:11/9/2015)... , Nov. 09, 2015 ... addition of the "Global Law Enforcement ... offering. --> ) has ... Law Enforcement Biometrics Market 2015-2019" report ... and Markets ( ) has announced ...
(Date:11/4/2015)... November 4, 2015 --> ... report published by Transparency Market Research "Home Security Solutions Market ... Forecast 2015 - 2022", the global home security solutions market is ... by 2022. The market is estimated to expand at ... 2015 to 2022. Rising security needs among customers at ...
(Date:10/29/2015)... , Oct. 29, 2015   MedNet Solutions , ... entire spectrum of clinical research, is pleased to announce ... Tech Association (MHTA) as one of only three finalists ... "Software – Small and Growing" category. The Tekne Awards honor ... have shown superior technology innovation and leadership. ...
Breaking Biology News(10 mins):
(Date:11/23/2015)... ... ... Noblis, Inc., a leading provider of science, technology, and strategy services, announced ... (NGA), has joined the Noblis NSP team as President of the organization. , ... the private sector,” said L. Roger Mason, Jr., Ph.D. , Senior VP, National ...
(Date:11/23/2015)... and PISCATAWAY, New Jersey ... Cambridge Crystallographic Data Centre (CCDC) announces the ... Structural Database (CSD) and the CSD-System, now complemented ... worldwide: CSD-Discovery to support the discovery of new ... and CSD-Enterprise, the complete set of the CCDC,s ...
(Date:11/23/2015)... , Nov. 23, 2015  CryoLife, Inc. (NYSE: ... focused on cardiac and vascular surgery, announced today that it ... Jaffray Healthcare Conference on Wednesday, December 2, 2015 at The ... . Pat Mackin , President and Chief ... and Chief Executive Officer. --> A live ...
(Date:11/23/2015)... Nov. 23, 2015  Oxis Biotech, Inc. (OXIS), ... [OTC: OXIS] and [Euronext Paris: OXI.PA] announced today ... Cancer Center received notification from the U.S. Food ... with their planned combination Phase 1/Phase 2 clinical ... to develop and commercialize OXS-1550, a novel therapy ...
Breaking Biology Technology: