Tre1 NRY domain is required for response to Wunen-mediated death. (A) tre1⁺ embryos average with ∼24 germ cells in the gonads by stage 12 or later. (B) Overexpression of Wunen in the soma (tub_p-wun2::myc written as wun2 OE, red) results in massive germ cell death. (C–G) Germ cells with NRY (C) or NPIIY (E) mutant Tre1 receptors or germ cells (G) expressing the dominant-negative form of Gαo remain in the midgut or scatter in the embryo. (D) Overexpression of somatic wunen does not alter the NRY mutant phenotype. (F) Overexpression of somatic wunen in NPIIY embryos kills the majority of germ cells that exit the midgut. (H) Overexpression of wunen in embryo expressing Gαo dominant-negative form in germ cells kills the majority of germ cells. All embryos are viewed from dorsal. The midgut is outlined in yellow hashes and the gonad in white hashes to distinguish between different germ cell populations. (I) Quantification of number of germ cells is shown for germ cells outside the midgut, as they are susceptible to Wunen-mediated germ cell death. For total number of germ cells see Fig. S4 C. Bar, 50 µm. ***, P < 0.001. Error bars represent standard deviation. For crossing schemes and genotypes, see Table S1.