Rod-Specific Ablation Using the Nitroreductase/Metronidazole System to Investigate Regeneration in Xenopus

Genetically controlled cell type–specific ablation provides a reproducible method to induce regeneration that can be temporally and spatially controlled. Until recently, regeneration studies in Xenopus have relied on surgical methods to stimulate regeneration. These methods are labor intensive and not as reproducible as a genetically controlled approach. In this protocol we describe selective ablation of rod photoreceptors in the premetamorphic Xenopus laevis retina using the nitroreductase/metronidazole (NTR/Mtz) system. We use the XOPNTR transgenic line in which the Xenopus Rhodopsin promoter drives rod photoreceptor-specific expression of the bacterial enzyme, NTR. Exposure of transgenic tadpoles to Mtz for 2 d completely ablates rods by 7 d after initial Mtz exposure. Removal of Mtz allows rods to regenerate and makes rod-specific ablation reversible and amenable for regeneration studies. The protocol presented here is applicable to the selective ablation of any cell type with the use of appropriate cell type–specific promoters.