Figure 6

NOS expression in Placozoans. (A,B) NADPH-diaphorase histochemistry and the distribution of putative nitrergic cells in two species of Placozoa: Trichoplax adhaerens (A) and Hoilungia hongkongensis (B). NADPH-d reactive cells (black) are broadly distributed across the animal. In both species, relatively large cells (asterisks) correspond to so-called “shiny spheres,” whereas the arrows indicate an example of different NADPH-d reactive cells with some tendencies of their distribution close to the edge of animals. (C) Expression of two NOSs in Trichoplax using single molecules fluorescent in situ hybridization (smFISH, pseudo-color). Blue dots—NOS-3 and purple dots—PDZ-containing NOS-1. A dotted circle indicates an example of a cell where both NOS are co-localized within the same cell. Note, NOS-expressing cells do not occur at the very edge of the animal. Scale: 10 µm.