Figure 4

Figure 4

Copper exposure induces cell death and subsequent regeneration in the olfactory sensory system. (A,B) TUNEL assay for copper-induced damage to olfactory organ (OO). Whole mount, 5 dpf larva. (A) Control fish showed no cell death. (B) Only the OOs were positive for TUNEL, green, arrows, DAPI (blue). (C) Quantification of TUNEL fluorescence control and treated animals. (D,E) Frontal view of Tg(trpc2:GFP):Tg(lysC:DsRed) with microvillous sensory neurons (MSN, green) extending into OB in control animals (D) and 4 h posttreatment (E). Neutrophils (red) in the OO, but unlike OSNs, microvillous OSNs were largely unaffected. (F) Quantification of microvillous OSNs (green, fluorescence) in control (gray) and copper-treated animals (red); no significant decrease in Trpc2:GFP fluorescence was observed. All fluorescence was normalized using DAPI (n = 3 larvae, two-way ANOVA, Tukey multiple-comparisons test, ****a = P < 0.0001, b = P < 0.01). All scale bars = 100 μm.