Genomes of Malaria-Carrying Mosquitoes Sequenced: New View of Disease-Transmitting Insect

Scientists have taken a step forward when it comes to understanding the genetics behind disease-carrying insects. They've sequenced the genomes of 16 Anopheles mosquito species, which are responsible for transmitting human malaria parasites.

Malaria parasites are estimated to cause about 200 million cases of malaria and more than 600 thousand deaths each year. However, of the almost 500 different Anopheles species, only a few dozen carry the parasite, and only a handful of species are responsible for the majority of transmissions. Understanding the genetics behind this could, potentially, help scientists develop methods for combating the spread of this disease.

"We selected species from Africa, Asia, Europe and Latin America that represent a range of evolutionary distances from Anopheles gambiae, a variety of ecological conditions, and varying degrees of vectorial capacity," said Nora Besansky, one of the researchers, in a news release.

The scientists collected high-quality DNA samples for all of the species. Then, they sequenced the genomes from these species. This revealed new insights into the genes responsible for reproductive processes, immune responses, insecticide resistance and chemosensory mechanisms. What was interesting is that the scientists spotted high rates of gene gain and loss that were about five times higher than in fruit flies. Some genes, such as those involved in reproduction or those that encode proteins secreted into the mosquito saliva, have very high rates of sequence evolution.

"The question of the true species phylogeny has been a highly contentious issue in the field," said Besansky. "Our results show that the most efficient vectors are not necessarily the most closely-related species, and that traits enhancing vectorial capacity may be gained by gene flow between species."

The findings could potentially help scientists better combat malaria. But understanding the species that transmit this disease, researchers can develop methods to prevent its spread.

The findings are published in two papers here and here in the journal Science.

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