Fig. 5

wnt3a is expressed in the medial mesoderm, flanked by fli1a-positive cells, while lef1 is expressed in a subpopulation of fli1a-positive cells. (A) Position of the fli1a-positive progenitor cell population in a 14 hpf old zebrafish embryo (blue). Left: lateral view, Right: dorsal view, with the red box at the posterior side indicating the region of analysis. (B-C) Double in situ hybridization for fli1a (red) and wnt3a (blue). Wild type embryos showed wnt3a expression in the medial mesoderm, flanked by fli1a expressing tissue (B, higher magnification b). In homozygous> cloche mutant embryos lacking ECs and erythrocytes, fli1a expression was absent, while wnt3a expression could be detected in the medial mesoderm in a patchier pattern compared to the wild type siblings (C). (D-G) In situ hybridization for fli1a or/and lef-1. fli1a was expressed bilaterally in posterior LPM (D, higher magnification d). In comparison, lef1 was also expressed bilaterally in the posterior LPM, but in a narrower region (E, higher magnification e) and additionally in the tailbud (asterisk). Moreover, the bilateral expression of fli1a (red) and lef1 (blue) was absent homozygous cloche mutant embryos (G), compared to the wild type siblings (F, higher magnification f). (H,I) Confocal maximum intensity projections of fluorescent double in situ hybridization of fli1a (red) and lef1 (green) (H, higher magnification h) and subsequent software based co-localization analysis (I, higher magnification i) indicated co-expression of lef1 in a subset of fli1a expressing cells.