Fig 3. UV cones are efficiently ablated using our model of cell specific ablation.

Prior to treatment with prodrug metronidazole (MTZ), most UV cones (green, labelled with antibody 10C9.1 against UV opsin) express the nfsb-mCherry transgene (magenta). A-C. Wholemount retinae viewed en face (tangential plane). 81±4% of UV cones express the nfsb-mCherry transgene, considering all 1622±96 UV cones across the entire retina of 7 days post-fertilization (dpf) larvae (n = 5), the age at which they would begin to receive MTZ in our ablation paradigm. Scale bar in panel J is 20 μm. D-K. Larval zebrafish expressing the transgenes Tg[sws1:KalTA4; UAS:nfsb-mCherry-KalTA4] in the UV cones, such that UV cones contain the nitroreductase-mCherry fusion protein (pseudocoloured magenta). Top row: UV cones are intact in retinal sections of transgenic larvae treated with the vehicle control (DMSO, applied at 7 dpf). Bottom row: UV cones are ablated, as shown in retinal sections of transgenic larvae treated with the prodrug MTZ (applied via bath treatment for 24 hours beginning at 7 dpf; the end of this 24 hours is labeled as zero hours since the end of drug treatment). A decrease in the number of mCherry-positive UV cones (magenta) is apparent through 48 hours post ablation, followed by observation of mCherry-fluorescing blue cones at the ciliary marginal zone (panel H). Auto-fluorescence is included for spatial reference (Green). Scale bars are 50 μm. L. UV cones were reduced in abundance four-fold after prodrug MTZ treatment (red bars) relative to vehicle control (DMSO; grey bars). Abundance of cones in the peripheral retina is represented by lighter grey or red bars. UV cones were gradually added to the periphery (light red bars) on the days following MTZ. Quantification considered UV cones in the peripheral retina and mature retina (⌘ indicates p<0.0001 when comparing UV cone abundance in mature retina treated with MTZ relative to DMSO, and p<0.05 when comparing peripheral retina treated with MTZ relative to DMSO; ❖ denotes significant difference (p<0.0001) when comparing UV cones in mature retina with MTZ relative to DMSO, but peripheral UV cone abundance is not significantly different between treatments. n≥5 fish for each treatment).