A chimeric gene paternally instructs female sex determination in the haplodiploid wasp Nasonia

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Science  27 Nov 2020:
Vol. 370, Issue 6520, pp. 1115-1118
DOI: 10.1126/science.abb8949

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Paternal factor specifies female wasps

Not all animals have specialized sex chromosomes to determine their sex. In hymenopteran insects, for example, unfertilized eggs become males and fertilized eggs become females. Prior work showed that the paternal genome provides instruction for female development. Zou et al. identified a sex determination instructor gene, wasp overruler of masculinization, with parent-of-origin effect, in the parasitoid Nasonia vitripennis. It is only transcribed from the paternally provided genome in fertilized eggs to initiate female development. This discovery provides insights into the molecular basis and evolution of sex determination.

Science, this issue p. 1115


Various primary signals direct insect sex determination. In hymenopteran insects, the presence of a paternal genome is needed to initiate female development. When absent, uniparental haploid males develop. We molecularly and functionally identified the instructor sex-determination gene, wasp overruler of masculinization (wom), of the haplodiploid wasp Nasonia vitripennis. This gene contains a P53-like domain coding region and arose by gene duplication and genomic rearrangements. Maternal silencing of wom results in male development of haploid embryos. Upon fertilization, early zygotic transcription from the paternal wom allele is initiated, followed by a timely zygotic expression of transformer (tra), leading to female development. Wom is an instructor gene with a parent-of-origin effect in sex determination.

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