Figure 5

The activities of Her3, Her5, Her9 and Her11 together account for the progenitor pool pattern of the midbrain-hindbrain area and do not influence her8a expression. A-D. A comparison of the expression patterns of her3, her5, her9, her11 and neurog1 at 3 somites in the midbrain-hindbrain (MH) area using double in situ hybridization (color-coded), on dorsal views of flat-mounted embryos. Arrows point to the her5/her11 domains co-expressing her3 or her9. E-J. Compared neurogenesis in control embryos (E,G,I) and embryos co-injected with the four gripNA antisense oligonucleotides directed against her3, 5, 9 and 11 transcripts (see Methods) (F,H,J). E,F. Expression of neurog1 (revealed by in situ hybridization against gfp in -8.4neurog1:gfp transgenic embryos) [62]: the majority of the MHB/r2 area is induced to express neurog1. G,H. The expression her8a is unaltered upon injection of the four gripNAs. I,J. Detection of GFP in -8.4neurog1:gfp embryos at 24 hpf (sagittal view, confocal projection of a 20 μm section of the neural tube). Ectopic neurons are formed ventrally across the midbrain-hindbrain boundary (position of the boundary indicated by the white bar), in a location normally devoid of GFP-positive cells (arrowheads). K,L. Summarized compared expression of her3, 5, 9 and 11 (K), also together with her8a (L). M-Q. Summary of the combined loss-of-function results for MH-expressed her genes, from Geling et al. [13] (M), Ninkovic et al. [22] (N), Bae et al. [11] (O,P) and the present paper (Q). Abbreviations: mid: midbrain, MN: presumptive motoneurons, r: rhombomere, r2l: lateral neurons of rhombomere 2, vcc: ventro-caudal cluster.