A sponge allelochemical induces ascidian settlement but inhibits metamorphosis

摘要: Secondary metabolites synthesised by sessile invertebrates appear to play a role in creating and maintaining space on hard substrata repelling competitors. In this study, we investigated the responses of larvae ascidian Herdmania curvata haliclonacyclamine A (HA), major component suite cytotoxic alkaloids extracted from sponge Haliclona sp. 628. Both 628 inhabit crest slope Heron Island Reef. High rates settlement were induced competent H. range concentrations HA, all lower than that naturally occurring sponge. HA did not induce precompetent settle. Although early metamorphosis HA-induced was normal, exposed but lowest concentration developmentally arrested after completion tail resorption, at about 4 h initiation metamorphosis. These postlarvae underwent extensive cellular necrosis within 24 h. We also demonstrate addition transcriptional inhibitor, actinomycin D, causes inhibition resorption is completed. Analyses incorporation radiolabelled nucleotides measure levels transcription during normal development inhibitor indicate there significant burst activity just Despite inhibiting same stage as increases initial RNA synthesis induction manner similar observed until onset necrosis. conclude initially induces settle progress through possibly engaging pathway other artificial environmental cues subsequently inhibits metamorphosis, resulting death postlarvae. Since does affect overall rates, it appears disrupt another important developmental process