Expression analysis of syndecan-2 mRNA expression in zebrafish. (A) At 17 to 18 hpf (15-16 somite stage), syndecan-2 is expressed in the brain, the hypochord (ii, arrows), and the mesendoderm (ii, arrowheads). Anterior end is to the left. Panel Aii is an expanded image of panel Ai that shows the mid-trunk section of the embryo. This localized syndecan-2 expression pattern persists through 23 hpf (B), 27 hpf (C), and up to 33 hpf (D). (E) A transverse section through the trunk of a 24-hour embryo showing expression of syndecan-2 in the dorsal neural tube, the hypochord (arrowhead), ventromedial somites, the mesenchyme surrounding the dorsal aorta and cardinal vein, and the endoderm. DA indicates dorsal aorta; CV, cardinal vein; NT, neural tube; So, somite; and No, notochord. (F) High-magnification image of the area around dorsal aorta in panel E. Arrowheads indicate syndecan-2–expressing cells surrounding the dorsal aorta (DA). (G) RT-PCR analysis showing expression of syndecan-2 mRNA (top row) and elongation factor 1α (loading control, bottom row) at 2, 6, and 13 hpf. (H) The coding sequence of zebrafish syndecan-2. The single underline indicates the predicted signal sequence. The double underlines denote the predicted hydrophobic transmembrane segment. The rectangles indicate the predicted heparan sulfate attachment sites. The cytoplasmic domain of syndecan-2 consists of 2 conserved (C) regions and one variable (V) region.46 The C1 region consists of amino acids 177 to 188. The variable region (V) consists of amino acids 189 to 199. The C2 region consists of amino acids 200 to 209. (A-F) In situ hybridization; original magnification, × 10 (A-D); × 20 (E); and × 40 (F).
