Fig. 2

Expression of wnts and β-catenin reveal cellular and not regional expression patterns. a) Whole sponge at 5 dph showing regions of the body including the gemmule, G, osculum, osc, choanosome, ch with choanocyte chambers and canals and bordered in yellow – and the peripheral region, per, shown by the white border. b) Expanded view of boxed area in a). Archaeocytes (arch) and algal cells (alg) in the peripheral region shown by DIC. Inset shows amoeboid archaeocytes. c), d) silicatein M2 (positive control) in situ hybridization in 2 and 5 dph sponges, respectively (whole mount top; inset bottom). Sclerocytes are spindle-like in shape (arrowheads). e) - h) Expression of EmuwntA, EmuwntB, EmuwntC, and Emuβ-catenin mRNA in archaeocytes of the peripheral region. Double in situ hybridizations of i) wntA and C in the choanosome near the choanocyte chambers and j) wntA and B in the peripheral region. c) - e) and g) - h) NBT/BCIP, f) Fluorescent in situ hybridizations with wnt labels in green and/or red and nuclei in blue (Hoechst). k) Anti-β-catenin staining (green) in peripheral tissue of Spongilla lacustris, nuclei are indicated in blue (Hoechst), and merged with DIC. Arrowheads in e), f) and g) indicated labeled archaeocytes, arrowheads in j) indicate algal symbiont auto-fluorescence (alg). Scales: 50 μm