Fig. 2

Fluorescent microscopy (OC1, ×40) and quantitative assay for hair cell damage in the five and six days post-fertilization (dpf) transgenic zebrafish (Brn3C: EGFP).

The 5 and 6-dpf transgenic zebrafish were treated simultaneously with 125 μM neomycin and various concentrations (10, 100, 250, and 500 μM) of sodium selenite for 1h. Treatment with neomycin resulted in a significant decrease in the number of hair cells, but 500μM sodium selenite most attenuated the hair cell damage (A). Hair cells from four neuromasts (SO1, SO2, O1, and OC1) were analyzed. The total hair cells of negative control group had 41.90 ± 5.19 cells. Treatment of the transgenic zebrafish with 125 μM neomycin for 1 h significantly decreased the number of hair cells in the neuromast (20.80 ± 3.61 cells). Sodium selenite protected against neomycin-induced hair cell loss in a dose dependent manner. The concentration of 500 μM of sodium selenite had significantly protective effect against neomycin (*: statistically significant) (n = 10 fish per treatment, B). NM 125 μM: 20.80 ± 3.61 cells, p<0.01, compared to negative control; S 10 μM + NM 125 μM: 18.00 ± 2.36 cells, p<0.01 and 0.61, compared to negative control and NM 125 μM, respectively; S 100 μM + NM 125 μM: 28.40 ± 2.76 cells, p<0.01, p<0.01, and p<0.01, compared to negative control, NM 125 μM, and S 10 μM + NM 125 μM, respectively; S 250 μM + NM 125 μM: 35.10 ± 2.69 cells, p = 0.02, p<0.01, p<0.01, and 0.03, compared to negative control, NM 125 μM, S 10 μM + NM 125 μM, and S 100 μM + NM 125 μM, respectively; S 500 μM + NM 125 μM: 39.10 ± 4.53 cells, p = 0.61, p<0.01, p<0.01 p<0.01, and p = 0.21, compared to negative control, NM 125 μM, S 10 μM + NM 125 μM, S 100 μM + NM 125 μM, S 250 μM + NM 125 μM, respectively (B). * statistically significant: Scale bar = 10 μm. NM, neomycin; S, sodium selenite.