On first light this seems impressive and good. But does this gene
insertion transfer to any predators that may be in the watery home of
the larvae. If it is not transferable in any way to other animals,
bacteria or fungi then it could be a revolutionary change in control of
many parasitical diseases passed on by these arthropods.
But, I believe nature will find a way to circumvent this control and
that could present other problems.
D.
On 01/10/2012 3:00 PM, michael gurstein wrote:
*From:*[email protected]
[mailto:[email protected]] *On Behalf Of *William Finseth
*Sent:* Monday, October 01, 2012 1:16 PM
*To:* CAIDC Admin
*Subject:* [Caidc-rccdi] New GM Frankenmisquitos
FYI
GM trials slash dengue mosquito numbers
Helen Mendes
25 September 2012 | EN |ES
/Aedes aegypti/mosquitoes transmit dengue fever, which kills 22,000
children every year
Shutterstock
[CURITIBA, BRAZIL]Genetically modified (GM) mosquitoes released into
the environment,during a trial in the Cayman Islands, reduced the
population of dengue-carrying/Aedes aegypti/mosquitoes by 80 per cent,
according to a study.
The findings, published this month (10 September) in/Nature
Biotechnology/, were followed by anothersuccessful trial of GM
mosquitoes in Juazeiroregion, Brazil, where a controlled release of
GM/A. aegypti/reduced the mosquito population in the region by 90 per
cent, according to a press release by the Brazilian science ministry
issued last week (20 September).
The GM mosquitoes for the Cayman Islands trial were developed by the
UK-based biotech company Oxitec. Around 3.3 million sterile male
mosquitoes, which do not bite people and so do not spread dengue, were
released in a site in Grand Cayman, over a period of 23 weeks in 2010.
The sterile male mosquitoes mate with wild, non-GM females, and pass a
gene, inserted into GM mosquitoes by scientists, which causes their
offspring to die before reaching adulthood, thus preventing them from
reproducing and leading to a reduction in mosquito populations.
By the trial's end, scientists found an 80 per cent reduction in the
number of mosquitoes in the 16 hectare trial area, compared to
untreated areas.
"It is an extremely encouraging result and the first demonstration
that you can suppress a target population through the release of
engineered male mosquitoes," Luke Alphey, Oxitec's chief scientific
officer, told/SciDev.Net/.
However, environmental andanimalwelfare group GeneWatch remains
sceptical about the effectiveness of using this method to tackle dengue.
"To achieve that level of suppression, they had to increase
significantly the number of GM mosquitoes they expected to release...
That's not a very efficient method for reducing the [naturally
occurring] population," Helen Wallace, executive director of GeneWatch
UK, told/SciDev.Net/.
Alphey said that Oxitec calculated a ratio of GM to wild mosquitoes
needed to supress numbers, but given that it is difficult to determine
the total number of mosquitoes in an area, Oxitec had to increase the
number of released GM mosquitoes.
GeneWatch also raised concerns that the possibility of a small
percentage of GM mosquitoes surviving could pose risks to the public
health, as they may end up being more effective at transmitting other
diseases, such as yellow fever.
But Constância Ayres, a researcher from the department of entomology
at Fiocruz Pernambuco, a Brazilian research institute, believes the
method is safe.
"It is not a transgene [a transferred gene] that will remain in
nature. It sterilises offspring, so it has no role in the epidemiology
of the disease. The gene will not persist in the environment," Ayres
told/SciDev.Net/.
However, Ayres is not confident the approach is cost-effective.
"I believe this is a promising tool, but we are a long way from using
it in nationwide controlprogrammes. Production [of GM mosquitoes] is
still a limiting factor. I don't think it's feasible [to carry out
programmes] in big cities."
In order to scale up GM mosquito production and roll out, Oxitec has
built a new factory in Brazil. Oxitec is still waiting for the
Brazilian ministry ofhealthto use their ideas in national control
programmes, and further trials --- particularly in large urban centres
--- are required.
"This tool could be added to a well-established control programme ---
for instance when you need to momentarily suspend the use of
insecticides, you would have another option," said Ayres.
Alphey emphasised that the use of these GM insects in the wild has
been approved by regulatory bodies in the three countries --- Brazil,
the Cayman Islands and Malaysia --- where it has been tested.
"The persistence of genetic material in the environment is a major
issue for regulatory agencies, but different regulatory authorities
have independently concluded that there is no significant risk from
this," he said.
The WHO estimates that 50 to 100 million dengueinfectionsoccur each
year, causing 500,000 cases of dengue haemorrhagic fever and 22,000
deaths, mostly among children.
Link to article in/Nature Biotechnology/
Link to Brazilian science ministry's press release(in Portuguese)
REFERENCES
/Nature Biotechnology/doi:10.1038/nbt.2350 (2012)
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