Fig. 5

Visual system phenotype in mbx-MO-injected embryos. (A–D) Expression patterns of retinal markers at 48 hpf. The expression of rx1 in retina is down-regulated in cont-MO-injected (A), but retained in mbx-MO-injected embryos (B). Islet1 and lim3 are activated in the retina of cont-MO-injected (C, E) but not mbx-MO-injected embryos (D, F); in contrast, expression of both genes in the hindbrain is not affected (D, F). (G–J, M–P) Retinal phenotype at 48 hpf (G–J) and 5 dpf (M–P). The number of RGCs and retinal axons, as visualized by zn-5 immunostaining, is greatly reduced in mbx-MO-injected embryos (H, N) compared with controls (G, M). (G) and (H) are shown at the same brightness setting to illustrate the absence of signal in (H). Nuclear staining using SYTOX (green) shows that retinal lamination is disorganized in mbx-MO-injected embryos (I, J, O, P). (K, L, Q, R) Retinotectal projections at 5 dpf. For clarity, the labeled eyes have been digitally removed. (K, L) The right and left eyes were labeled with diI (red) and diO (green), respectively. The number of retinal axons is greatly reduced in mbx-MO-injected embryos (L), but the remaining axons project normally to the contralateral side. (Q, R) Both eyes were labeled with diD (red), and the embryo was stained with SYTOX (green), which outlines the tectal border (tb) but does not label the cell-sparse tectal neuropil (tn). The size of the tecta, and especially the neuropil, was reduced in mbx-MO-injected embryos (R)