Fig. 4

Fig. 4 Anti-NT-3 induces Rohon Beard cell death, whereas NT-3 reduces death and leads to an increase in trkC1-expressing neurons. (A–G) Dorsal views of 22-hpf (A, C, E, G) and 20-hpf (B, D, F, H) explant cultured spinal cords with anterior to the left. (A–D) Control preparations showing explants labeled to reveal HNK-1-expressing RB neurons (A), trkC1-expressing RB cells in an explant treated with anti-NT-3 (20 ng/ml) and NT-3 (2 ng/ml) (B, arrow indicates trkC1⁺ cell), TUNEL-labeled apoptotic cells (C, arrow indicates large RB cell undergoing cell death), and trkC1-expressing RB cells in a control explant (D, arrow indicates trkC1⁺ RB cell). (E) Explant treated with anti-NT-3 (20 ng/ml) for 6 h exhibiting an increased number of dying RB cells (arrows) compared to C, as determined with TUNEL. Some other cells in the skin and spinal cord are also dying (arrowheads). (F) Explant treated with anti-NT-3 (20 ng/ml) for 4 h exhibiting a decreased number of trkC1-expressing RB cells compared to D. (G) Explant treated with NT-3 (2 ng/ml) for 6 h exhibiting a decreased number of dying cells as determined by TUNEL compared to C. (H) Explant treated with NT-3 (2 ng/ml) for 4 h exhibiting an increased number of RB cells expressing trkC1 compared to D. (I) Graph showing the number of TUNEL-positive RB cells per 26-somite stage (22 hpf) zebrafish explant in untreated, anti-NT-3-treated (20 ng/ml), NT-3-treated (2 ng/ml), and both anti-NT-3 (20 ng/ml) and NT-3 (2 ng/ml)-treated conditions. (J) Graph showing the number of trkC1-positive RB cells per 22-somite stage (20 hpf) zebrafish explant in untreated, anti-NT-3-treated (20 ng/ml), NT-3-treated (2 ng/ml), and both anti NT-3 (20 ng/ml) and NT-3 (2 ng/ml)-treated conditions. Values represent means ± SEM of five separate determinations ***P < 0.01, *P < 0.05 according to the Student t test.