CRISPR-Cas9 gene mutation code modification
PREVENTING THE MOSQUITO’S DEADLY BITEComparisons and results
In a previous study, DeGennaro used
the gene-editing system CRISPR-Cas9 to
knock out the gene for an odor receptor on their
olfactory neurons to see how it would affect a
mosquito’s ability to find a human to bite. Sure
enough, mutant mosquitoes without the gene for
the receptor, called Orco, had more trouble than
regular mosquitoes at differentiating between
humans and other animals.
But even without Orco, they were still able to
find humans. This meant there had to be other odor
receptors that allowed them to locate humans.DeGennaro tried again
In a new study, he used CRISPR to disrupt the
gene for a different odor receptor known as IR8a.
The researchers compared the behavior of female
mosquitoes with and without the IR8a gene by
putting the insects in a plastic tube with an odor
box attached upwind of it. If the mosquitoes were
attracted to what they sensed in the box, they would
fly toward it and get stuck in a small trap.Using this contraption, they found that in
the presence of CO2 and human odor, 75 percent
of the unaltered mosquitoes got stuck in the trap,
compared with 50 percent of the IR8a mutants.
In another experiment using an artificial blood
feeder, 75 percent of normal Aedes aegypti would
feed in the presence of CO2, human odor and heat,
compared with around 30 percent of the mosquitoes
whose IR8a gene had been knocked out.
The results, published in Current Biology,
demonstrate that the IR8a gene plays an important
role in helping female mosquitoes find humans. This
gives scientists a potentially useful target for keeping
mosquitoes away from us.
“Our goal is to figure out how mosquitoes find
people and then use that information to create a
life-saving perfume,” DeGennaro said.Vocabulary Focus
© Cambridge University Press 2008
thwart (v) [>wOrt] to stop something from happening or someone from doing something
assassin (n) [/:s,sIn] someone who kills a famous or important person, usually for political reasons or in exchange for money
arsenal (n) [:Ars/n/l] a collection of weapons
stealthy (adj) [:stEl>i]
stealth (n) [stEl>] movement which is quiet and careful in order not to be seen or heard, or secret action
differentiate (v) [;dIf/:rEn{i;et] to show or find the difference between things which are compared
upwind (adv) [:<p:wInd] in the direction from which the wind is blowing102030152505Specialized Terms
malaria (n) [m/:lEri/]
yellow fever (n)
neurobiologist (n) [;nUrobaI:Al/d}Ist]
chikungunya (n) [;t{ikun:gunj/]
receptor (n) [rI:sEpt-]
vertebrate (n) [:v=t/brIt]
CRISPR-Cas9 (n) [:krIsp-k,snaIn]
olfactory (adj) [Al:f,kt/ri]
mutant (adj) [:mjutnt]More Information
contraption (n) [k/n:tr,p{/n]
a device or machine, often one that you
don’t know how to operateDeGennaro’s next step
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