Fig. 7. The PSR morpholino-induced defect morphant can be rescued by injection of psr mRNA. PSR-MO at 20 ng and psr mRNA at 20 pg were injected at the one- to two-cell stage, embryonic development was traced at 12 (A-D), 48 (E-H) and 72 (I-L) hpf. (A,E,I) Untreated embryos; (B,F,J,N,O) embryos injected with control-MO; (C,J,K,P,S) PSR-MO-injected embryos; (D,H,I,R,S) embryos injected with PSR-MO and psr mRNA. (A-D) By 12 hpf, PSR-MO-injected embryos had accumulated corpse cells in whole embryo (E, arrows); these were not observed in the rescued embryos (D), or in controls (A,B). (E-H) At 48 hpf, PSR-MO morphants were severely defective (G, long arrow), whereas embryos in the rescued group were only weakly defective (H, short arrow). The morphology of the control-MO-injected embryos (F) is comparable to that of wild type (E). (I-L) At 3 dpf, rescued embryos (L) were compared with PSR-MO-injected embryos (K), wild-type variants (I), and control-MO-injected embryos (J). In contrast to the severely-defective morphant (K), the trunk and heart cavity of rescued embryos (L, arrows) resembles those of wild-type (I) and control-MO (J) embryos. (M) Estimation of the protection ability of differing doses of psr mRNA. D, dose; N, number of embryos. (N-S) At 3 dpf, rescued embryos (O,R) reveal normal morphology and a normal psr expression pattern in the kidney (arrows), as shown in control-MO embryos (N,Q), when compared to the PSR-MO-injected embryos (P,S). Scale bars: A-H, 250 µM; I-L, 200 µM; N-P, 100 µM; Q-S, 50 µM.