Fig. 2

Fig. 2 Calcium protects hair cells from neomycin in a dose-dependent manner. (A) Fish were acutely exposed to 100 μM neomycin in embryo medium with variable Ca²⁺ concentration and hair cell survival was assessed with the vital dye DASPEI. The arrow indicates the MI1 neuromast in each image as a reference, while the arrowhead points to the olfactory epithelium, which serves as an internal labeling control. Numbers on each image indicate the Ca²⁺ concentration. The scale bar in the “control” image is 0.5 mm. (B) Mean hair cell survival following acute 100 μM neomycin exposure was assessed using DASPEI scoring (dashed line) from 10 neuromasts per fish or by direct counts of YO-PRO-1-labeled hair cells (solid line) from four neuromasts per fish. Mock-treated controls are not shown but are represented by the 100% level. Increased calcium shows significant protection against neomycin at this dose (two-way ANOVA, p < 0.001) (C and D). Dose-response curves for acute (C) and continuous (D) neomycin exposure in embryo medium containing either 300, 900, 1500, or 2100 μM Ca²⁺. Mean hair cell survival significantly increases with increasing external Ca²⁺ for either exposure time course (p < 0.001). The legend in panel C applies to both C and D. N = 9–16 fish/treatment, error bars are ±1 SD.