The female of the species is more deadly than the male, the famous author Rudyard Kipling wrote, and that is certainly true of the mosquito Aedes aegypti , also known as the yellow fever mosquito. Only party women human blood, not only the transmission of yellow fever, but dengue fever and many other diseases. But if you could turn all the mosquitoes in men? It's a possibility raised by new research that highlights the gene that determines whether a mosquito becomes male.
Scientists have known for decades that at least one gene that makes A. aegypti male embryos resides on a strand of DNA on chromosome 1. They called this part of the locus M but so far they have been unable to identify the specific gene. Part of the problem: The region contains large amounts of repetitive DNA, making it difficult to sequence this region. (Imagine a huge puzzle of the sea. It is almost impossible to know which part belongs where) In fact, as it appeared, a A. aegypti genome published in 07 does not even contain the gene newly identified. "It is very small and it was thrown in the trash," said Zach Adelman, a molecular geneticist at the Institute and State University Virginia Polytechnic Blacksburg and one of the authors of the new paper.
to find the gene, Adelman and colleagues sequenced thousands of pieces of DNA of male and female mosquitoes belonging to two different strains of A. aegypti and looked for stretches that were more frequent males of both strains. They found 164 such sequences and their correspondence with the data showing which genes are active in embryos, looking for sequences that appeared to be active in the early male embryos. in the 24 sequences that remain, they found a new gene, which they named Nix .
About half of the female embryos injected with a piece of DNA containing this gene developed male genitals, the report researchers online today science . (They do not check whether these animals would be able to bite humans and transmit diseases.) "The exact sequence of events that leads to mosquito development that men are not clear," Adelman said. " But we know that Nix is at the top of the waterfall and that's what counts. "
" This is an excellent basic science and it has the potential for genetic control strategies, "says Bart Knols, an entomologist who has In2Care, a company in Wageningen, The Netherlands, which develops mosquito traps. a first application would be to assist with the control strategies that already exist. a company called Oxitec, for example, produced the mosquitoes that carry deadly gene that kills the offspring in early development, which can significantly reduce mosquito populations. But half of the produced mosquitoes are women who can not be released because they could help spread the disease they are supposed to fight. "The whole system would be cheaper and more effective if you could produce only males," Knols said.
First, however, scientists need to show they can achieve full gender reassignment, knols warnings. Only a few women have become men in the study, because the Nix gene must be integrated into the genome of the mosquito for the protein to be produced in sufficient quantities, said Adelman. "If it is produced all the time in all tissues, hopefully completely converted obtain the fully fertile males. We are working hard on it."
In the long term, this could lead to another strategy. Scientists have recently reported a system that allows them to push a certain gene in the next generation to almost 100% frequency. The coupling of Nix gene to such a system would essentially create a chain reaction spreading of the male gene. "If you release such an animal, it produces only men until eventually crashes the population," said Adelman. But it is much too early to implement such a technique, he admits. "We need technology to control such systems before can be used. "
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