Fig. 6

Brain-Specific Expression and a Role for Smcx in Neuronal Survival during Zebrafish Development

(A) RNA in situ hybridization of whole-mount zebrafish embryos. In (a–f), antisense smcx RNA probe hybridized with embryos at the time points indicated. Arrows point to the neural tube, and arrowheads indicate muscles that were weakly stained. In (g–l), or the control, sense smcx probe hybridized with embryos of the same developmental stages.

(B) Smcx is required for proper neuronal development and survival. Zebrafish embryos injected with two independent antisense morpholinos (MO 1 and 2) to smcx show developmental delay and have abnormal brain patterning (black arrowheads) at 24 hr postfertilization (hpf) compared with embryos injected with a control morpholino. At 48 hpf, knockdown embryos show moderate ventral curvature of the tail. Acridine orange (AO) staining at 30 hpf reveals dramatic cell death throughout the brain (white arrowheads) and neural tube (white arrows) in knockdown embryos.

(C) Transplantation of MO-treated cells to wild-type embryos. Live cell bodies labeled with green dye in the head of most morpholino-treated cells are visible, and often long neuronal processes can be observed (b). Most smcx MO-treated cells with red dye formed small diffuse spots, likely to be dead cell aggregates (c). Bright field view is shown in (a).