Fig. 6

The regular cone mosaic lattice is disrupted in tbx2b mutants.

A, C) Cone mosaic lattice in the dorsal retina (A) and ventral retina (C) visualized in retinal flat-mounts of adult, wild-type, double transgenic (UV and blue cone reporter) fish. Cell profiles are stained with anti-ZO-1 (white). Rows of UV cones (magenta) and blue cones (blue) alternate with red-green double cones. Smaller, rounded ZO-1 profiles represent rods and irregular profiles are Müller glial processes. The inset shows a cartoon of the cone pattern; rods are represented by black dots. Rarely, cones are missing from the lattice (indicated by blue star in A and magenta star in C). The yellow circle encloses a UV cone surrounded by rods. B) Retinal flat-mount near the dorsal retinal margin of a tbx2b mutant with the UV cone reporter. Immunolabeling with ZO-1 (white) reveals absence of a rectilinear order, independent of the presence of the unusually large UV cones (magenta). This fish did not carry the blue opsin reporter transgene. D) Retinal flat-mount from ventral retina in a tbx2b mutant double transgenic: blue cones (blue) and red-green double cones (white profiles); UV cones are absent from the ventral retina. The red box delimits a region used for cone cell counts. E) Retinal flat-mount from wild-type, rod reporter transgenic fish with rods (green) and cones (white profiles). F) Retinal flat-mount from tbx2b mutant adult with rod reporter. Scale bars: 20 μm (A,B,C,E,F) and 20 μm (D).