Nasal shifts in retinal patterning in fgf8-mutant ace embryos. (A-J) In situ hybridizations of wild-type and the fgf8-mutant acerebellar (ace) at 28 hours. Expression of foxg1 is confined to the nasal retina but not expressed to the dorsal-most point in wild type (A) and reduced (asterisk) in the dorsonasal retina of ace mutants (B). Expression of efna5a covers the complete nasal retina in wild type (C) and is reduced overall in ace (D). Expression of epha4b is confined to the temporal retinal half of the wild type (E), is fully complementary to efna5a (C) and expands (asterisk) into the nasal retina in ace (F). Expression of tbx5 is confined to the dorsomedial retina in the wild type (G) and reduced in its nasotemporal extent in ace (H). vax2 is expressed in the ventral retina of the wild type (I) and unaffected in ace (J). (K-M) Intensity profiling of gene expression in the dorsal retina along a clockwise 180° trajectory (L). (K) Graphs of intensity profiles of wild type (black) and ace mutant (blue) retinae (mean values, n=8 eyes/gene): in the wild type, foxg1 is expressed in a nasal-to-temporal decreasing gradient, which is shifted nasally in ace (16° offset in Emax/2). The nasal-to-temporal decreasing gradient of efna5a in the wild type is reduced overall and shifted nasally in ace (13° offset in Emax/2). The nasal-to-temporal increasing gradient of epha4b in the wild type is nasally shifted owing to upregulation of expression in ace (11° offset in Emax/2). The bell-shaped expression gradient of tbx5 in the wild type is steeper in ace (13° offset in Emax/2 nasally and temporally) and the central peak of tbx5 expression, –Emax value-, is shifted nasally in the mutant (radial offset=12°). Axial positions in radial degrees along the profiling trajectory (x-axis) are plotted against the expression level in gray values on an 8-bit scale (y-axis). Drop-lines in K indicate points of half-maximal Emax/2 and maximal Emax expression; corresponding expression values, radial positions and representative standard deviations (error bars) are indicated. (M) Schematic representations of gene expression domains. Boundaries are deduced from Emax/2 values in K. Extent of expression domains in wild type and ace are color-coded as indicated. Orientation of eyes as indicated in A. D, dorsal, V, ventral, N, nasal, T, temporal. Broken outlines indicate the lens. Arrowheads indicate the ventralmost position of the eye.
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