Meeting Abstract
A distinguishing cell type in cnidarians is the cnidocyte. Previous studies of cnidogenesis indicate that the same progenitor cell gives rise to cnidocytes and neurons. The differences between neurons and cnidocytes can be investigated by examining gene expression for specific cell types. Hydra, a well-studied animal for cell differentiation, has been a useful model for cnidogenesis, but little is known about cnidogenesis in other cnidarians. Minicollagen, a novel protein, is the main protein responsible for the structural elements of the mature cnidocyte. Using immunohistochemistry and in situ hybridization, we examined the expression of candidate genes for cnidogenesis in wild type embryos to verify if the same genes in Hydra are present in Nematostella. ZNF845, a gene present in Interstitial cells in Hydra, plays a role in cnidocyte development. To understand ZNF845’s role in cnidogenesis in Nematostella, we injected embryos with a ZNF splice-blocking morpholino. Knockdown of ZNF845 resulted in both a decrease in the quantity of cnidocytes and number of cells expressing three putative cnidocyte-specific transcription factors: nanos, mef2 and NR12 (COUP-TF). To understand cnidocyte structure and regulation, we manipulated the expression of three minicollagens using translation-blocking morpholinos. Using DAPI staining to detect mature cnidocytes, we confirmed a lack of mature cnidocytes in these treatments. In situ hybridization of minicollagen knockout embryos shows no compensation for the loss of minicollagen proteins by the cnidogenesis pathway, since no significant differences in expression of cnidocyte-specific transcription factors were found. These results suggest that in N. vectensis, ZNF845 is upstream in cnidogenesis and that all three minicollagens are necessary for normal cnidocyte development.
