NOV 18, 2017 12:55 PM PST

The Risks & Rewards of Genetically Altered Mosquitoes

WRITTEN BY: Carmen Leitch

Mosquitoes with edited genomes have been created in the lab, with the aim of reducing disease and controlling mosquito populations. In 2015 researchers reported the use of ‘gene drive’ in mosquitoes, in which the passage of edited DNA onto offspring is promoted, and occurs at a rate that is higher than the typical 50 percent, so instead of diluting a trait in subsequent generations, it spreads. As such, organisms that carry gene drives can impact wild populations disproportionately, making significant changes very quickly in a large number of offspring.

CRISPR/Cas9-mediated disruption of genes associated with eye pigment caused eye color to change from Black to white. / Credit: Michelle Bui, UC Riverside.

Now researchers at the University of California, Riverside report making transgenic mosquitoes that carry the genome-breaking Cas9 enzyme in their germline, which would allow for the targeted editing of mosquito genomes. They are aiming to improve on previous efforts to use edited mosquitoes to reduce disease, which has not gone as well as was hoped.

By developing mosquitoes that express Cas9, the CRISPR gene editing tool can be applied to them, and specific genes they carry can be altered. For proof-of-concept, the team has shown that this technique enabled the disruption of genes that control feeding, vision, and flight. The resulting in mosquitoes had an extra eye, defects in eye and cuticle color, malformed wings, and other changes.

"These Cas9 strains can be used to develop split-gene drives which are a form of gene-drive by which the Cas9 and the guide RNA's are inserted at separate genomic loci and depend on each other for spread. This is the safest way to develop and test gene drives in the laboratory to ensure no spread into the wild," Akbari said.

CRISPR/Cas9-mediated disruption of genes associated with cuticle pigment caused mosquitoes to turn from black to yellow, and disruption of genes associated with eye pigment caused eye color to change from black to white. / Credit: UC Riverside.

One idea is to disrupt fertility in the bugs as an environmentally friendly and inexpensive way to reduce populations of insects that spread disease.

"Next steps should be undertaken to identify the regulatory sequences that can be used to express the guide RNAs from the genome, and once these sequences are identified developing gene drives in the species should be turnkey," Akbari said.

Caution has been urged by members of the scientific community. Pilar Ossorio, Morgridge bioethicist in residence and UW-Madison law professor, has commented on the new technology, noting that although human clinical trials are subject to stringent regulations, other genome editing applications are less scrutinized, like gene drives.

"There are safety and environmental concerns about releasing an organism that has a gene drive into the wild," Ossorio said. "But security experts also worry about a gene drive that could be used to gradually poison a food supply, or enable a mosquito to transmit more rather than less virus."

The tool is still in relative infancy, but it is not difficult to use it. As such it may be very tough to assess the dangers it presents before it's applied to our environment. "Gene editing is unprecedented in that it gives us the capability to make hundreds of genetic changes at the same time, and the process can be done in people, other animals and in plants,” Ossorio said.

Time will undoubtedly tell more tales about the applications of these tools, and we will have to confront the ethical questions that arise. The video above from the Howard Hughes Medical Institute BioInteractive YouTube Channel explains more. The video below is a lecture about modifying mosquitoes with CRISPR, by the American Museum of Natural History.

Sources: AAAS/Eurekalert! Via UC Riverside, PNAS, Morgridge Institute for Research 

About the Author
  • Experienced research scientist and technical expert with authorships on 28 peer-reviewed publications, traveler to over 60 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
NOV 20, 2018
NOV 20, 2018
A Major Grant Aims to Improve our Understanding of Age-related Cognitive Decline
The American Heart Association has teamed up with the Allen Initiative in Brain Health and Cognitive Impairment to award the Salk Institute $19.2 million....
DEC 01, 2018
Cell & Molecular Biology
DEC 01, 2018
Illuminating the Role of Membraneless Organelles
Princeton researchers created new tools to study liquid phase separation inside of cells, and how it influences cell behavior....
DEC 03, 2018
DEC 03, 2018
Genes Involved In Dementia Identified
Genetic factors have also been recognized as a critical contributor for dementia and identifying these genes will eventually allow for gene-specific therapeutics to be developed. Although sci...
DEC 20, 2018
DEC 20, 2018
A Genetic Test for Sociability in Dogs
It may be possible to swab a dog's cheek and do a genetic test to see if it would make a good service dog....
JAN 05, 2019
Health & Medicine
JAN 05, 2019
The CRISPR Craze - New Frontiers in Gene Editing
The CRISPR/Cas system is an adaptive prokaryotic immune system which allows bacteria to inhibit viral infection. In 2012, Jennifer Doudna and Emmanuelle Charpentier were...
JAN 08, 2019
JAN 08, 2019
Ebola Relative is Discovered
Bats are a vital part of the ecosystem, but they also host deadly viruses. Scientists have now discovered a new filovirus in a bat....
Loading Comments...