Fig. 5. Altered gene expression in the Ripply2-null embryos. Whole-mount in situ hybridizations were employed to characterize somitogenesis in the Ripply2^-/- embryo. The expression of caudal genes such as Uncx4.1 (A,B) and Dll1 (C,D) was found to be reduced, whereas rostral genes such as Tbx18 (E,F) and Epha4 (G,H) show an expanded pattern in Ripply2^-/- embryos at E11.5. (I-N) Comparisons of the expression patterns of Mesp2 mRNA, detected by exon (I,J) and intron (K,L) probes, and protein levels (M,N), at E10.5. An additional Mesp2 expression band appears rostrally in the Ripply2^-/- embryos (J,L). Mesp2 protein expression, visualized by Mesp2-venus, was compared between the Ripply2^+/- (M, n=2) and Ripply2^-/- (N, n=3) genetic backgrounds. The confocal images were visualized by fluorescence, detected using anti-GFP antibodies. (O,P) Comparison of the Lfng expression patterns at different cyclic phases (indicated by I to III) at E10.5. The oscillatory expression of Lfng (asterisks) in the posterior PSM was unaffected, but the rostral-most expression bands (brackets) are slightly expanded in the Ripply2^-/- embryos (P), as compared with the Ripply2^+/- embryos (O). (Q,R) The prolonged expression of Lfng in the anterior PSM. The PSM of E10.5 Ripply2^+/- (Q) and Ripply2^-/- (R) embryos was separated into two halves, with one being fixed immediately and the other fixed after explant culturing for 20 minutes. Both were then analyzed for Lfng mRNA. The expression of Lfng in the anterior PSM is maintained for longer in the Ripply2^-/- embryos.