Targeted Rod Photoreceptor Ablation in Transgenic Xenopus Laevis

Abstract

Purpose: : Rod photoreceptor death is a common feature of blinding diseases such as retinitis pigmentosa. We have developed a transgenic approach to specifically ablate rod photoreceptors in the retina of Xenopus laevis in order to mimic rod cell loss.

Methods: : Our method utilizes the E.coli enzyme nitroreductase, and its ability to reduce the antibiotic metronidazole to a DNA cross-linker. In theory, metronidazole treatment will kill any cell expressing nitroreductase via DNA damage. We have generated a transgenic line of frogs driving nitroreductase expression under the control of the rod specific rhodopsin promoter.

Results: : Metronidazole treated transgenic tadpoles show a dramatic loss in rod photoreceptors when compared with wild type and untreated transgenic animals. Rod cell ablation was metronidazole dose and time dependent. Using a behavioral assay we also show that vision loss is correlated with rod photoreceptor cell death. Cone photoreceptor loss followed rod cell death in treated animals; suggesting that retinal changes may mimic those observed in rod-cone dystrophies. Additional changes in the retina following rod ablation will also be described.

Conclusions: : These results suggest this cell ablation technique may be a useful tool for studying the mechanisms driving retinal degenerations and potentially retinal regeneration.

Keywords: retina • retinal degenerations: cell biology • photoreceptors