FIGURE 1

Expression patterns of nine opsin subtypes in 4dpf larval zebrafish eyes in wildtype vs. trβ2 gain-of-function under euthyroid and hyperthyroid conditions, detected using multiplex fluorescence in situ hybridization chain reaction (HCR). (A) Representative confocal projections of whole-mounted eyes from wildtype and Tg (crx:MYFP-2a-trβ2) larvae. In transgenics, lws2+ cone density is increased at the expense of other cone opsin + subtypes and rod opsin + cells. Insets show magnified views of boxed areas to highlight the cone mosaic structure. (B) Opsin mRNA localization within a 3500 μm² area dorsal to the optic nerve head following treatment with 100 nM T3. In transgenic, T3-treated larvae, lws2, sws1, sws2, rh2-1, and rh2-2 positive cells (bottom row) are substantially reduced compared to T3-treated wildtype larvae (top row). (C) Scatter plot showing the average number of rod opsin+ and cone opsin + cells per unit area, quantified from confocal images of wildtype (gray) and transgenic (yellow) retinas. The final plot in C shows the % change in expression of indicated photoreceptor opsin in T3-treated vs. control, for 3,500 μm² areas averaged over all samples. P-values were calculated using One-way ANOVA across four groups (WT + DMSO, WT + T3, GOF + DMSO, GOF + T3), followed by six pairwise post hoc comparisons (Tukey’s test). Statistical significance is represented as *P < 0.05, **P < 0.01, ***P < 0.001, ***P < 0.0001. N ≥ 6. D = Dorsal and N = Nasal. Scale bar in A = 50 μm.