What if we could simply genetically alter mosquitos to cause their eventual extinction? Mad science, or realistic possibility?
GM mosquitoes a ‘quantum leap’ towards tackling malaria
New technique injects mosquitoes with a gene that results in mostly male offspring, eventually leading to a population crash
Scientists have hailed the genetic modification of mosquitoes that could crash the insect’s populations as a “quantum leap” that will make a substantial and important contribution to eradicating malaria.
Previous efforts to tackle the disease, that kills more than 1 million people each year – most of whom are African children – have included bed nets to protect people and insecticides to kill the mosquito species most responsible for the transmission of malaria (Anopheles gambiae).
The new technique by a team at Imperial College London involves injecting mosquitoes with a gene that causes the vast majority of their offspring to be male, leading to an eventual dramatic decline in population within six generations as females disappear.
“You have a short-term benefit because males don’t bite humans [and transmit malaria],” Andrea Crisanti, one of the authors of the new research, which was published in the journal Nature Communications on Tuesday, told the Guardian.
“But in the long term you will eventually eradicate or substantially reduce mosquitoes. This could make a substantial contribution to eradicating malaria, combined with other tools such as insecticides.”
The scientists injected mosquitoes with a gene from slime mould – a homing endonuclease called I-PpoI – which attached itself to their X chromosome during the male’s sperm-making process and effectively shredded part of the chromosome’s DNA. The result was that more than 95% of the mosquitoes offspring were males. The researchers found that the modified mosquitoes mated with wild mosquitoes, creating fertile mosquitoes which then overwhelmingly produced male offspring, passing on the gene.
“Under field conditions the accumulation of X chromosome damage would significantly contribute to the demise of target populations,” the scientists say in their paper.
“The engineering is a quantum leap in terms of what has been done before,” said Crisanti, who worked on previous research in 2008, which took a similar approach but unintentionally resulted in sterile mosquitoes, meaning the gene’s ability to spread was limited. Imperial College London also published work in 2011 on a distinctly different approach to impair the fertility of mosquitoes generally, rather than distorting the makeup of their sex.
Nikolai Windbichler, a research fellow at Imperial College London and co-author, said that the concept of distorting the sex of a pest’s population is more than 50 years old but that the technology had not been available until now to execute the idea.
“The concept was suggested by Bill Hamilton [the famous evolutionary biologist, W.D. Hamilton], but until now there wasn’t a way to realise it. There are selfish chromosomes around but they’re too complicated, so we created something like this from scratch [the homing gene using synthetic biology], he said. “We found mosquitoes have a genetic achilles heel.”
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http://www.theguardian.com/environme...ion?CMP=twt_gu