(A) Sequence alignment of NvePTx1 and its homologs from other cnidarian species. The arrowhead represents the proteolysis site that separates the mature toxin from the signal peptide. Accession numbers appear near each sequence. Nve = Nematostella vectensis; Bcs = Bunodosoma caissarum; Ael = Anthopleura elegantissima; Mse = Metridium senile; Hsy = Hydractinia symbiolongicurpus. (B–C) Zebrafish larvae 16 hr after incubation in NvePTx1 and BSA control. (D) Detection of NvePTx1 expression by ISH. From the blastula stage on, the oral pole is to the right. Close up on planula large elongated (E–F) and small round (G) gland cells stained by ISH for NvePTx1. Gland cells, which are discernible by their round vesicles are free of stain, scale bar is 10 µm. (H–I) An adult F0 female polyp that as a zygote was injected by an NvePTx1::mOrange2 construct. mOrange2 expression is noticeable in the gonads. Panel G is a close up of the region indicated in panel H by the yellow dotted box. Scale bar is 1000 µm (J) An egg package laid by the female from panel H. Many of eggs express mOrange2. Scale bar is 1000 µm. (K–M) Large elongated and (N–P) small round gland cells stained by anti mCherry. Scale bar is 10 µm.