Meeting Abstract
Sea anemones employ cnidae, specialized capsules produced in cnidocytes, to capture prey. Anemones develop from planula larvae to polyps that form tentacles containing cnidae. Two types of cnida occur in tentacles, adhesive spirocysts and penetrant nematocysts. We characterized cnidae during developmental stages in the model sea anemone, Nematostella vectensis, using spirocysts density:nematocyst density ratios. Planulae contain only nematocysts and no spirocysts (ratio 0.00). Spirocysts first appear in primary polyps coinciding with the formation of 4 tentacles but are far outnumbered by nematocysts (ratio 0.46+ 0.04). Spirocysts increase in density as polyps develop 5-10 tentacles but nematocysts remain the dominant cnida type (ratio 0.65+ 0.16). In adults having 16 tentacles, spirocysts outnumber nematocysts in tentacles (ratio 2.19+ 0.38). Thus, the formation of spirocysts is delayed compared to nematocysts in developing anemones and continues through polyp maturation. Pattern formation in epithelia often involves Delta-Notch signaling and this pathway has been implicated in cnidogenesis in planulae. We asked whether Notch signaling is involved in the differentiation of cells that form spirocysts (spirocytes) during polyp maturation. We inhibited Notch in polyps with 5-10 tentacles with DAPT. DAPT treatment resulted in no significant change in the mean spirocyst:nematocyst ratio (0.54+ 0.08) but resulted in a decrease of overall cnidae abundance. Our results suggest that the Delta-Notch pathway is involved in the regulation of cnidogenesis in maturing polyps. Continuing experiments are resolving if another cell type increases upon inhibiting Delta-Notch and the identity of the presumed cell type. (See companion abstract, “Hair Bundle Abundance in Nematostella vectensis is Regulated by Delta-Notch”)
