Ablating UV cones does not cause any detectable off-target cell death.

<p>Transgenic zebrafish engineered for UV cone ablation were labeled for apoptosis using TUNEL to examine death of target photoreceptors (UV cones) and any effects on adjacent photoreceptors. <b>(A, B)</b> Zebrafish larvae that had received either vehicle control (DMSO) or prodrug metronidazole (MTZ) treatment, respectively, sacrificed at 9 days post fertilization (dpf). UV cones expressing mCherry are pseudocoloured in magenta, TUNEL labelling is represented in green, nuclei are in cyan. Intact UV cones are not detectable in the prodrug treated larva. <b>(C)</b> Quantification of the number of TUNEL-positive cells per section within the ONL. The number of TUNEL+ mCherry- cells did not differ significantly between treatment groups, indicating no detectable off-target cell death. The number of TUNEL+ mCherry+ cells differed significantly between groups, as was expected since the prodrug treatment is designed to induce apoptosis in the mCherry+ UV cones of this transgenic model. * = p<0.05. n = 5 & 9 fish for the DMSO & MTZ treatment groups, respectively. Scale bar is 100μm.