Abnormal activation of IFN-γ signaling attributed to the impaired development of neutrophils in 142ab^−/− mutants. (A-F) Sudan black staining of neutrophils in wild-type embryos (A) and 142ab^−/− embryos (B) and 142ab^−/− embryos injected with stat1a MO (C), irf1b MO (D), stat1a MO and irf1b MO (E), and stat1b MO (F). (G) Quantification of SB⁺ cells in whole embryos. *P < .05 or **P < .01; 2-tailed Student t test. (H-K) Morphologic analysis of zlyz:eGFP⁺ cells from 3-dpf embryos. zlyz:eGFP⁺ cells were sorted from Tg(zlyz:eGFP) embryos (H); 142ab^−/−; Tg(zlyz:eGFP) embryos (I); 142ab^−/−; Tg(zlyz:eGFP) embryos injected with stat1a MO (J); or 142ab^−/−; Tg(zlyz:eGFP) embryos coinjected with stat1a MO and irf1b MO (K) at 3 dpf and stained with Wright-Giemsa solution. (L-O) The percentage of immature, bilobed, and multilobed neutrophils in zlyz:eGFP⁺ cells. (L) Tg(zlyz:eGFP) embryos (immature neutrophils 81.2%, SD = 2.20; bibilobed neutrophils 17.2%, SD = 2.50; and multilobed neutrophils 1.6%, SD = 1.14). (M) The 142ab^−/− embryos (immature neutrophils 55.7%, SD = 2.43; bibilobed neutrophils 31.1%, SD = 2.26; and multilobed neutrophils 13.2%, SD = 1.78). (N) The 142ab^−/−; Tg(zlyz:eGFP) embryos injected with stat1a MO (immature neutrophils 62.9%, SD = 3.82; bibilobed neutrophils 29.5%, SD = 3.17; and multilobed neutrophils 7.6%, SD = 1.01). (O) The 142ab^−/− ; Tg(zlyz:eGFP) embryos coinjected with stat1a MO and irf1b MO (immature neutrophils 73.8%, SD = 2.32; bibilobed neutrophils 23.8%, SD = 2.56; and multilobed neutrophils 2.5%, SD = 0.47). At least 100 cells were counted per experiment; SD, from 3 independent experiments. (P) Comparison of the percentage of bilobed or multilobed neutrophils in zlyz:eGFP⁺ cells. *P < .05 or **P < .01 vs wild-type; 2-tailed Student t test. (Q) Quantification of SB⁺ neutrophils recruited to neuromasts. *P < .05 or **P < .01 vs wild-type; 2-tailed Student t test.