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The insect sex determination and the intimately linked dosage compensation pathways represent a challenging evolutionary puzzle that has been solved only in Drosophila melanogaster. Analyses of orthologs of the Drosophila genes identified in non-drosophilid taxa1,2 revealed that evolution of sex determination pathways is consistent with a bottom-up mode,3 where only the terminal genes within the pathway are well conserved. doublesex (dsx), occupying a bottom-most position and encoding sex-specific proteins orchestrating downstream sexual differentiation processes, is an ancient sex-determining gene present in all studied species.2,4,5 With the exception of lepidopterans, its female-specific splicing is known to be regulated by transformer (tra) and its co-factor transformer-2 (tra2).6-20 Here we show that in the African malaria mosquito Anopheles gambiae, a gene, which likely arose in the Anopheles lineage and which we call femaleless (fle), controls sex determination in females by regulating splicing of dsx and fruitless (fru; another terminal gene within a branch of the sex determination pathway). Moreover, fle represents a novel molecular link between the sex determination and dosage compensation pathways. It is necessary to suppress activation of dosage compensation in females, as demonstrated by the significant upregulation of the female X chromosome genes and a correlated female-specific lethality, but no negative effect on males, in response to fle knockdown. This unexpected property, combined with a high level of conservation in sequence and function in anopheline mosquitoes, makes fle an excellent target for genetic control of all major vectors of human malaria.

Original publication

DOI

10.1016/j.cub.2020.12.014

Type

Journal article

Journal

Current biology : CB

Publication Date

03/2021

Volume

31

Pages

1084 - 1091.e4

Addresses

The Pirbright Institute, Ash Road, Pirbright, Surrey GU24 0NF, UK.

Keywords

Animals, Anopheles, Drosophila melanogaster, Malaria, DNA-Binding Proteins, Drosophila Proteins, Nerve Tissue Proteins, Transcription Factors, Dosage Compensation, Genetic, Female, Male, Sex Determination Processes, Mosquito Vectors