Fig. 6. Morpholino-induced knockdown of psr results in defective brain, heart and notochord development. Morphological analysis of embryos injected with 40 ng control (A,C,E,G,I,J) or PSR morpholinos (B,D,F,H,K,L), and examined at 36 hpf (A,B,E,F) or 3 dpf (C,D,G-I), following staining for pax2.1 (A,B) or nkx2.5 (E-H), or with Acridine Orange (AO; I-L), or in the absence of stain (C,D). (A,B) Top view, anterior to the right; stained with pax2.1. (C,D) Lateral views. The PSR-MO-injected embryo (B) shows an enlarged brain (long arrow) and an abnormal pax2.1 expression pattern (short arrows), when compared with the control-MO-injected embryo (A). The enlarged brain includes fore-, mid- and hindbrain morphologies (indicated by the open square in Fig. 6D; comparative control is shown in C). (E-L) Investigation of heart development. (E-H) At 36 hpf, the PSR-MO-injected embryos reveal an absence of normal heart formation (F, arrows and asterisks), when compared to the atria (A) and ventricles (V) observed in controls (E). By 3 dpf a tube-like heart has formed in the PSR-MO-injected embryos (H,K,L; arrows), as compared with normal controls (G,I,J). (M-U) The effect of knockdown of psr on notochord formation at 3 dpf. PSR-MO-injected embryos (N,P,R,T,U) show abnormal morphological formation such as the bending of the notochord (N, arrows), when compared with the control-MO group (M,O,Q,S). Scale bars: 100 µM.