Dpy19l1l is required for the Reissner fiber formation via regulation of SCO-spondin secretion. A-C, Blight field images of scospondin-GFPut24/+; dpy19l1l−/+ (A) and scospondin-GFPut24/+; dpy19l1l−/− (B, C) embryo at 2 dpf. Curved (B) or straight (A, C) bodies were observed. Scale bar; 500 μm. D-I, Maximum intensity Z-projection of confocal stack of scospondin-GFPut24/+; dpy19l1l−/+ (D, G) and scospondin-GFPut24/+; dpy19l1l−/− (E, F, H, I) embryo at 2 dpf. The central canal region on the dorsal side of yolk extension (D-F) and the caudal region, including the ampulla caudalis (G-I), were observed. Scale bar; 20 μm. J, L, N, Fluorescence images of scospondin-GFPut24/+; dpy19l1l−/+ (J) and scospondin-GFPut24/+; dpy19l1l−/− (L, N) embryo head at 2 dpf. scospondin-GFPut24/+; dpy19l1l−/− embryos show strong GFP localization at the Flexural organ (L, N). Scale bar; 500 μm. K, M, O, Schematic diagram of Sspo-GFP localization and RF structure in the central canal of 2 dpf embryo. In wild-type or dpy19l1l−/+ mutant, a straight RF structure was assembled, and Sspo-GFP localized apical side of floor plate cells (K). In curved dpy19l1l−/− mutants, RF structure was lost, and Spo-GFP accumulated at the basal side of floor plate cells, forming aggregates (M). In straight dpy19l1l−/− mutants, a very thin RF was observed, along with a bolus of Sspo-GFP-labeled Reissner material leading the RF assembly (O). P, Images of the spinal cord from 2 dpf actb2:arl13b-EGFPncv86/–; dpy19l1l+/+ or dpy19l1l−/− embryos. GFP fluorescence indicates cilia within the spinal cord. Scale bar; 2 μm.
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