FIG. 1.

Temporal and spatial analyses of the nocturnin mRNA expression in Xenopus retina by in situ hybridization. Xenopus eyes were dissected and fixed at ZTs 2 and 14, and 12-μm-thick cryosections were prepared. (A) In situ hybridization was done with a digoxigenin-labeled sense probe at ZT 14 (left) and antisense probes at ZT 2 (middle) and ZT 14 (right). Arrowheads point to the heavy in situ labeling in the inner segments and the perinuclear regions of the photoreceptor cells. (B) A higher-magnification image of the in situ staining at ZT 14 is shown. RPE, retinal pigment epithelium; PR, photoreceptor cells; OS, outer segments; IS, inner segments; ONL, outer nuclear layer (photoreceptor cell nuclei); INL, inner nuclear layer; GCL, ganglion cell layer.