CRY protein expression in the retina of migratory garden warblers and nonmigratory zebra finches. (a) Magnetic orientation of garden warblers. Each data point indicates the mean orientation of one individual. The arrows indicate group mean vector lengths (r). The orientation of the night-birds (Night) from which retinas were collected (green symbols) were highly oriented in the normal migratory direction (n = 11, mean = 223°, r = 0.77, and P < 0.001). The red dot represents the night bird whose retina is shown in b. During the day, the birds do not show orientation behavior (Day). mN, Magnetic North. (b) Immunohistochemical staining of CRY1 protein during nocturnal magnetic orientation (Left) and during the day (Right) in migratory garden warblers (images from the same slide taken with identical settings). Large displaced ganglion cells marked with arrow. (c) Immunohistochemical staining of CRY1 protein during the night (Left) and day (Right) in nonmigratory zebra finches (images from same slide taken with identical settings). Labeling of photoreceptor outer segments and Müller cell end-feet in b and c is unspecific. (d) Example of Western blot analysis confirming specificity of the antibody and quantification of CRY1 expression in the ganglion cell layer. For definition of intensity index, see Materials and Methods. Dashed line indicates unspecific background level of expression. GCL, ganglion cell layer; IPL, inner plexiform layer; OPL, outer plexiform layer; ONL, outer nuclear layer. (Scale bar, 40 μm.)
