Figure 4

Whole mount in situ hybridization of lectin coding genes A044-C2, A032-H1, A043-D8 and A043-H7. Localisation of (A) A044-C2, (B) A032-H1, (C) A043-D8 and (D) A043-H7 transcripts (dark purple) in (1) presettlement planula larvae, (2) settled polyps, and (3) cross sections of the latter with the mouth pointing upward. A044-C2 and A032-H1 are expressed in vase-shaped cells abutting the mesoglea some of which are putative cnidoblasts (Additional File 3), consistent with the presence of minicollagen-like domains. A043-D8 is expressed in ectodermal cells concentrated at the aboral end of larvae, and A043-H7 is expressed endodermally, consistent with a role in symbiont uptake via the digestive system. A4-D4 are schematic representations of the protein structures of the genes (not drawn to scale). The A043-D8 protein has a type C lectin domain distinct from the galactose-binding domains in the other three proteins, hence it is represented in a different colour.