Fig. 6

Changes in phagocytes surrounding deteriorating neuromasts and their effects on cluster formation. Larvae from the cross of Tg (mpeg1: mCherry) (red) and Tg(−8.0cldnb:NTR-hkiKGR;myl7:EGFP) (green) were treated with metronidazole (Mtz) as described in Figure 5, examined and photographed at designated hours or days post-Mtz treatment (hpMtz or dpMtz). We observed the disintegration of neuromasts post-Mtz treatment (A–D). Red macrophages (arrowheads) were recruited to engulf injured neuromasts in a dendritic cell-like shape within hours post-Mtz treatment (A–C). The injured neuromast disappeared, but macrophages were still retained in the injured site at 1dpMtz. Please note that the macrophages became more compact round in shape with protrusions (D). (E–G) Triple-transgenic larvae as designated were treated as described above, examined and photographed at 2 dpMz. Macrophages (red, white asterisks) were still found in the posterior lateral line system, even in a new neuromast, as shown in (G). In contrast, only a few neutrophils (bright green, yellow asterisks) were found. Scales are the same for each row but are only shown in the far-right panel. (H) We used larvae from the cross of Et(HG7L) and Tg(−8.0cldnb:NTR-hKikGR;myl7:EGFP). The larvae were treated without (ctrl) and with 3 μM diclofenac (with or without washout); control or clodronate liposome (H); or treated with different cytokine inhibitors PTX (35 μM) or LMT-28 (10 μM) (I). The above-treated larvae were undergone a 12-h Mtz treatment and scored for the % of larvae with cluster formation. Data represent mean ± s.e.m. and were analyzed by one-way ANOVA, *p < 0.05. n.s.: not significant.