Comparison of the Inducing Effect of Indole Compounds on Medusa Formation in Different Classes of Medusozoa.

ABSTRACT

Scyphozoa, Cubozoa and Hydrozoa are classes in the phylum Cnidaria that undergo metagenesis involving a dramatic morphological transition. In Scyphozoa and Cubozoa, when exposed to species- or strain-specific transition-inducing stimuli, asexually reproducing benthic polyps transform into sexually reproducing planktonic medusae. In Hydrozoa, exposure to species- or strainspecific transition-inducing stimuli causes formation of medusa buds in the polyp's body. In Aurelia aurita (Linnaeus, 1758) (Scyphozoa, Semaeostomeae), polyp-to-jellyfish transition is induced by some simple indole compounds. However, whether indole compounds can induce polyp-to-jellyfish transition in Cubozoa and Hydrozoa remains unknown. In the present study, we show that an indole compound, 5-methoxy-2-methylindole, induces polyp-to-jellyfish transition in Scyphozoa and Cubozoa. This inducing action suggests that the downstream steps of polyp-to-jellyfish transition are regulated by the same biochemical reactions in Scyphozoa and Cubozoa, irrespective of the type of transition-inducing environmental stimuli.