Tylodina perversa - chemical defence

January 26, 2003
From: Bill Rudman

While preparing Ferda's message I thought this summary of research on chemical defence in Tylodina perversa and its food sponge would be of interest.

Prof. Proksch's group at the Heinrich-Heine-University in Dusseldorf, Germany is one of many around the world studying the possible ecological functions of natural products found in marine invertebrates. For some years they have been looking at the metabolites of the Mediterranean sponges Aplysina aerophoba and A. cavernicola.

Healthy sponges accumulate brominated isoxazoline alkaloids. These secondary metabolites are highly effective fish deterrents and protect the sponges from predators. However when the sponge is injured these chemicals break down to form smaller molecules with strong antibacterial properties, which probably protect wounded sponges from invasion of bacterial pathogens. The origin of these chemicals in sponges and other marine invertebrates is not clear in many cases. However in Aplysina sponges, where microorganisms make up for up to 40% of the biomass, it is thought that this 'microflora' is responsible for at least some of the secondary metabolites.

Tylodina perversa is probably the last a chain of organisms involved in the production and useof these chemicals. In spite of the presence of these deterrent secondary metabolites in the tissue of Aplysina aerophoba, Tylodina feeds almost exclusively on this sponge. It not only tolerates the defensive metabolites but even sequesters them selectively in its own tissue, probably for defensive purposes against potential predators.

• Ebel, R., Marin, A. and Proksch, P. (1999) Organspecific distribution of dietary alkaloids in the marine opisthobranch Tylodina perversa. Biochemical Systematics and Ecology, 27: 769
• Friedrich, A. B., Fischer, I., Proksch, P., Hacker, J. & Hentschel, U (2001) Temporal variation of the microbial community associated with the mediterranean sponge Aplysina aerophoba. FEMS Microbiology Ecology, 38 105
• Teeyapant, R., Kreis, P., Wray, V., Witte, L. & Proksch, P. (1993). Brominated secondary compounds from the marine sponge Verongia aerophoba and the sponge feeding gastropod Tylodina perversa. Zeitschrift für Naturforschung, 48c: 640
• Teeyapant, R. & Proksch, P. (1993) Evidence for an induced chemical defense of the marine sponge Verongia aerophoba. Naturwissenschaften, 80: 369.
• Teeyapant, R., Woerdenbag, H. J., Kreis, P., Hacker, J., Wray, V., Witte, L. & Proksch, P. (1993) Antibiotic and cytotoxic activity of brominated compounds from the marine sponge Verongia aerophoba. Zeitschrift für Naturforschung, 48c: 939

Best wishes,
Bill Rudman

Rudman, W.B., 2003 (Jan 26) Tylodina perversa - chemical defence. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/9022

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