Fig 2

(A) Schematic of simple row insertion in cone mosaic. As new cone photoreceptors are incorporated to the right of the defect, a series of improper cone contacts (black box) within columns form. White dashed lines: rows associated with defect. (B) Schematic of a Y-Junction, a topological defect in the zebrafish cone mosaic. A Y-Junction only disrupts the cone mosaic near the core rather than along an entire line of contacts. White (black) dashed lines: rows (columns) associated with the defect. (C) A Y-Junction in a flat-mount retinal preparation from an adult, double transgenic (Tg[sws1:GFP; sws2:mCherry]) line in which UV and Blue cones express distinct fluorescent reporters (pseudo-colored magenta and blue, respectively) under control of UV and Blue opsin promoters, respectively. Antibody staining labels Red and Green cones (both pseudo-colored green). White (black) dashed lines: rows (columns) associated with the defect. (D) Each UV cone from panel C is connected (white bonds) to its nearest UV cone neighbors. To the left and right of the defect, rows are counted. Seven-sided (five-sided) star: seven-coordinated (five-coordinated) UV cone. (E) A circuit of triangulation bonds around defect from panels C-D. Red arrow is the Burgers vector, the additional bond necessary to close the circuit containing a dislocation. (F) Y-Junction in the same flat-mount retinal preparation as in Fig 1B. The round cells with dim fluorescence are UV cones. The Red cones are pseudo-colored red. The Blue cones are pseudo-colored blue. The remaining cones (bright gray fluorescence) are Green cones. We connect (solid white lines) nearest neighbors in the Red cone sublattice and Blue cone sublattice.