Expression patterns of aerolysin homologues in two cnidarian species. ISH was used in order to localize the expression of Nvlysin-1b in Nematostella vectensis and hydralysin-2 (Hln-2) in Hydra viridissima. In N. vectensis the expression was restricted to distinct large ectodermal cells in the pharynx (dark blue staining). Expression started in very few cells in 2-days old animals (A) and the domain expanded with age (B: 3-days old planula; C: 4-days old planula; D: 6-days old primary polyp). Nvlysin-1b is expressed in large cells (>40 μm), which probably are gland cells (unstained round spaces inside stained cells are vesicles, E). In H. viridissima, the aerolysin homologue Hln-2 is expressed in all endodermal cells in the gastrovascular cavity as shown by blue-purple staining in whole mount ISH (F) and a cross section of a stained animal (G). Scale bars are 50 μm in panels A–D, 40 μm in panel E, 500 μm in F, and 100 μm in G.
