Sex-converted testis somatic cells acquire female-specific behaviors and alter XY germline identity.

Establishment and maintenance of cellular sex identity is essential for reproduction. Sex identity of somatic and germline cells must correspond for sperm or oocytes to be produced, with mismatched identity causing infertility in all organisms from flies to humans. In adult Drosophila testes, Chronologically inappropriate morphogenesis (Chinmo) is required for maintenance of male somatic identity. Loss of chinmo leads to feminization of the male soma, including adoption of female-specific cell morphologies and gene expression. However, the degree to which feminized somatic cells initiate female-specific cellular behaviors or influence the associated XY germline is unknown. Using extended live imaging, we find that chinmo-depleted somatic cells acquire cell behaviors characteristic of ovarian follicle cells, including incomplete cytokinesis and rotational migration. Importantly, migration in both contexts require the basement membrane protein Perlecan and the adhesion protein E-cadherin. Finally, we find that sex-converted somatic cells non-autonomously induce expression of an early oocyte specification protein in XY germ cells. Taken together, our work reveals a dramatic transformation of somatic cell behavior during sex conversion and provides a powerful model in which to study soma-derived induction of oocyte identity.