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Fig. 1 Generation of a rod-specific, doxycycline-inducible, self-reporting gene expression system.
(A) Diagram of the construct used to generate a stable transgenic zebrafish line that expresses doxycycline (Dox)-inducible GFP specifically in rod photoreceptors. The Xenopus rhodopsin promoter (Xla.rho) drives expression of the reverse tetracycline-controlled transcriptional activator (rtTA) gene while the tetracycline responsive element (TRE) drives expression of GFP in the converse direction. (B, C) Confocal z-projections of retinal sections from 6 dpf Tg(Xla.rho:rtTA, TRE:GFP) larvae labeled with anti-Rhodopsin antibody (red). (B) No GFP fluorescence (green) is visible in the absence of Dox. (C) Rod photoreceptors show strong GFP fluorescence (green) when transgenic larvae are treated for 72 h with Dox (3–6 dpf). (D, E) Confocal z-projections of the photoreceptor layer of retinas from Tg(Xop:rtTA, TRE:GFP) adult fish labeled with anti-Rhodopsin (red) and anti-GFP (green) antibodies. (D) No anti-GFP immunofluorescence (green) is visible in the untreated adult photoreceptors, whereas strong anti-GFP immunofluorescence (green) is visible in the adult photoreceptors after treatment with Dox for 72 h (E). dA, polyadenylation signal; Tol2, pTol integration site. Scale bars, 50 µm.