A male-determining factor in the mosquito Aedes aegypti

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Science  12 Jun 2015:
Vol. 348, Issue 6240, pp. 1268-1270
DOI: 10.1126/science.aaa2850

Manipulating M factor alters mosquito sex

Female mosquitoes feed on blood and in so doing transmit pathogens to millions annually. Although the molecular mechanism for determining sex in many animals is known, the specific factors in mosquitoes have been elusive. This is because sex determination in insects involves a section of the genome that is highly repetitive. Hall et al. now identify a male-determining factor (M factor) in Aedes aegypti. Manipulation of the M factor produced sex-change phenotypes. Knocking out the gene Nix resulted in feminized males, and ectopic expression gave masculinized females. These findings should help to advance strategies for converting female mosquitoes into nonbiting males.

Science, this issue p. 1268


Sex determination in the mosquito Aedes aegypti is governed by a dominant male-determining factor (M factor) located within a Y chromosome–like region called the M locus. Here, we show that an M-locus gene, Nix, functions as an M factor in A. aegypti. Nix exhibits persistent M linkage and early embryonic expression, two characteristics required of an M factor. Nix knockout with clustered regularly interspaced short palindromic repeats (CRISPR)–Cas9 resulted in largely feminized genetic males and the production of female isoforms of two key regulators of sexual differentiation: doublesex and fruitless. Ectopic expression of Nix resulted in genetic females with nearly complete male genitalia. Thus, Nix is both required and sufficient to initiate male development. This study provides a foundation for mosquito control strategies that convert female mosquitoes into harmless males.

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