Gene that determines maleness in malaria mosquitoes

In a major step towards developing effective genetic strategies to control mosquitoes, scientists have isolated a gene that determines maleness in the species of mosquito that is responsible for transmitting malaria.

The researchers found that this gene, named Yob by the authors, could be lethal for the female population of the mosquito species which is primarily responsible for malaria transmission.

"Our research may have far-reaching implications for the control of malaria,” said lead researcher Jaroslaw Krzywinski, Head of the Vector Molecular Biology group at The Pirbright Institute in Britain.

The research, published in the journal Science, describes identification and characterisation of Yob which determines the male sex in the malaria mosquito Anopheles gambiae.

To identify Yob, the researchers used high-throughput sequencing to sample all transcripts (genetic messages) produced in the Anopheles gambiae male and female embryos. 

After comparison of the sequencing data, they found, exclusively in males, fragments of transcripts corresponding to Yob. 

Further research showed that Yob is encoded on the Y chromosome, and that activity of Yob was limited to males.

Unexpectedly, Yob transcripts are highly detrimental to females. When injected into mixed-sex early embryos of Anopheles gambiae, Yob kills females before they hatch from eggs, but leaves male development unaffected. 

Conversely, silencing normal embryonic Yob activity is lethal to males. 

These results indicate that, apart from determining maleness, Yob is pivotal for the control of another fundamental developmental process, called dosage compensation, which balances levels of transcripts from genes located on the single X chromosome in males and on two X chromosomes in females.

"The female-killing property of Yob gives us an invaluable tool for the engineering of male-only Anopheles strains suitable for malaria control in the future," Krzywinski said.