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ANIMALS: Genetic map completed for mass-killer mosquito

------------------------------- GENET-news -------------------------------
TITLE:  Genetic map completed for mass-killer mosquito
SOURCE: Reuters
AUTHOR: Will Dunham
DATE:   17.05.2007

Genetic map completed for mass-killer mosquito

WASHINGTON (Reuters) - The genetic blueprint of the mosquito that
spreads yellow and dengue fever is more complex than the one that
carries malaria, and scientists are hoping to use the information to
find ways to thwart the little killers.

Researchers on Thursday published the genome -- a map of all the DNA --
of the mosquito species Aedes aegypti, a connoisseur of human blood that
spreads disease in tropical and sub-tropical locales worldwide.

The genome, they said, could guide efforts to develop insecticides or to
create genetically engineered versions of this mosquito that are unable
or less able to transmit the viruses that cause yellow fever and dengue fever.

It is one of only a handful of insects whose genomes have been laid
bare, and the second mosquito species. The genome for Anopheles gambiae,
which carries the parasite that causes malaria, was published in 2002.
There are about 3,500 mosquito species, but these two cause the most
human misery.

Writing the journal Science, the researchers said the genome for Aedes
is about five times larger than the one for Anopheles. Both have roughly
16,000 genes, they said, but Aedes is loaded up with "junk DNA" and
other stuff whose function is unclear.

Aedes can transmit disease-causing viruses as it makes a meal out of
human blood.

Yellow fever, common in West and Central Africa and in parts of South
America, kills about 30,000 people annually. A vaccine has been around
for decades, but the number of people infected has risen in the past 20
years, according to the World Health Organization.

Dengue occurs in about 100 countries in tropical areas of the world and
kills about 25,000 people annually. There is no vaccine.


"These are huge global health issues," Vishvanath Nene of the J. Craig
Venter Institute in Rockville, Maryland, who led the study, said in a
telephone interview.

Mosquitoes first appeared 170 million years ago during the age of
dinosaurs. The yellow fever and malaria mosquitoes are believed to have
diverged evolutionarily from one another about 150 million years ago.

"They both are very robust, very fit mosquitoes. And they love to feed
on human blood," one of the researchers, David Severson of the
University of Notre Dame in Indiana, said in a telephone interview.

"Their physical appearance is quite different. And their behavior is
quite different. And as we see with their genome architecture, it's also
very, very different," Severson said.

The Aedes is a small, dark mosquito with white markings and banded legs
that originated in Africa. People unwittingly spread it worldwide
centuries ago when it hitchhiked on transoceanic voyages.

"Aedes is a beauty," Severson said. "Only an entomologist can love them
and say, 'OK, that's really a good-looking mosquito.'"

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