Fig 1. mdka expression and Mdka immunostaining during retinal development and in adults.

In situ hybridization showing mdka expression at stages between 30hpf and adults (A-F). Mdka immunostaining at stages corresponding to the in situ hybridizations are also illustrated (G-H and images merged DAPI counterstain below). At 30 hpf, Mdka immunofluorescence in strongest at the basal surface of the retina (panel G, arrows). At 48hpf, Mdka antibodies transiently label the nascent inner plexiform layer (panel H, arrows). At 120hpf, when differentiated photoreceptors are present, Mdka immunostaining is present in horizontal cells (arrows) and the outer nuclear layer (brackets). Though tested numerous times, the level of Mdka immunofluorescence dramatically decreases between 7–10 dpf (panel J, J’). Note that at this time point horizontal cells express mdka (panel D). In the juvenile retina, Mdka immunostaining returns and both horizontal cells (arrows, panel K, K’) and the overlying rod photoreceptors in the ONL are intensely stained. This juvenile pattern of immunostaining is present in adults, but the overall intensity of the immunostaining is reduced, and the immunostaining of horizontal cells is consolidated to a small immunofluorescent plaque lying adjacent to each DAPI-stained nucleus (arrows, panel L’). hpf, hours post fertilizations; dpf, days post fertilization; mo, months; ONL, outer nuclear layer; INL, inner nuclear layer; IPL, inner plexiform layer; CMZ, circumferential marginal zone. Scale bar in panel J’ equals 20 μm and corresponds to images in columns A-D and G-J. Scale bar in panel L’ equals 10 μm and corresponds to images in panels E, F, K, K’, L and L’.