|
Figure 6
(A) Representative confocal images of the central retina of control, tbx2a and tbx2b F0 mutants at 5 dpf, in double transgenic larvae that label M cones — or M-opsin expressing cells — with GFP (green) and S cones with mCherry (magenta). Both tbx2a and tbx2b F0 mutants display an increase in GFP-positive cells. In tbx2a F0 mutants, increase in GFP signal is excluded from mCherry-positive cells, producing a decrease in the space without fluorescence, while in tbx2b F0 mutants, increase in GFP signal is restricted to mCherry-positive cells, which appear as double positive (white) in the merged images. (B) Quantification of S cones in the central retina shows no significant changes in either tbx2a or tbx2b F0 mutants compared to control (Kruskal-Wallis H=3.668, p=0.16, nwt = 24, ntbx2a=18, ntbx2b=18). (C) Quantification of the fraction of GFP-positive S cones (double positive cells in A) reveals a significant increase only in tbx2b F0 mutants (Kruskal-Wallis H=35.584, p=1.87 × 10–8, nwt = 24, ntbx2a=18, ntbx2b=18; Conover-Iman posthoc corrected p-values: control vs. tbx2a p=2.87 × 10–5, control vs. tbx2b p=0.63, tbx2a vs. tbx2b p=1.13 × 10–6).
Tbx2b inhibits M-opsin expression in S cones.