In the laboratory, this gene search has eliminated a population of mosquitoes

A new gene campaign could kill a mosquito-carrying mosquito.

In a small-scale laboratory study, the genetic engineering tool caused Anopheles gambiae mosquitoes to stop producing their offspring in eight to twelve generations, researchers report September 24 Nature Biotechnology. If the results are valid in larger studies, the search for genes could be the first to eliminate a disease-carrying mosquito species.

"It's a great day," says James Bull, an evolutionary biologist from the University of Texas at Austin, who did not participate in the study. "We are here with a technology that could radically change public health for the whole world."

Gene readers use the molecular scissors known as CRISPR / Cas9 to copy and stick to an organism's DNA at specific locations. They are designed to break the rules of inheritance by rapidly propagating genetic modification to all children.

New gene mechanism disrupts gene called mosquito doubleex. Female mosquitoes that inherit two copies of the disturbed gene grow as males and can not bite or lay eggs. Males and females who inherit a single copy of the disturbed gene develop normally and are fertile.

In each of the two cages, the researchers mixed 300 women and 150 normal men. A. gambiae mosquitoes with 150 men carrying the gene drive. Each generation, 95% to more than 99% of the offspring inherited the genetic drive. Normally, only 50% of children inherit a gene.

In seven generations, all mosquitoes in a cage carried the gene. No eggs were produced in the next generation and the population died. In the other cage, it took 11 generations for the genetic drive to spread to all mosquitoes and crush the population.

Other gene research studies have conducted computer simulations to predict the time required for disk propagation in a population. This is the first time that the approach has succeeded on real mosquitoes.

Earlier versions of genes have also been transmitted to descendants at high rates (SN: 12/12/15, p. 16). But these experiments have been plagued by mutations that destroy the CRISPR / Cas9 cutting site, making the mosquitoes carrying the mutation resistant to the drive.

Some mosquitoes in the new study have also developed mutations, but "no resistance has been observed," says co-author of the study, Andrea Crisanti, medical geneticist of Imperial College London. . It's because these mutations broke the doubleex gene, producing sterile females that could not transmit the mutations to the next generation.

All insects have a version of doubleex. "We think this gene can represent an Achilles' heel for the development of new pest control measures," says Crisanti.

The tool opens the prospect of intentionally causing the extinction of a species. A. gambiae is the main mosquito that spreads malaria in Africa. According to the World Health Organization, malaria kills more than 400,000 people each year worldwide.

"If you have a technology that could eradicate that [mosquito]it would be unethical not to use it, "says Omar Akbari, a geneticist at the University of California San Diego, who was not involved in the work. But Mr. Akbari thinks that it is unlikely that gene research works as well in nature because resistance is expected to appear at a given time.

Nobody knows either the ecological consequences of eliminating mosquitoes or whether the genetic drive could be transmitted to other species. And if a "James Bond villain" used a similar genetic technique to attack bees or other beneficial insects, says geneticist Philipp Messer of Cornell University. "Humans will always find ways to abuse [technology]and in this case, it's so easy. That's what worries me.