NEW METABOLITES FROM MARINE SPONGES - ARE SYMBIONTS IMPORTANT

It has frequently been suggested that symbionts may produce marine nat ural products obtained from sponges. A critical examination of this hy pothesis reveals little supporting data although there may be circumst antial evidence favouring the involvement of symbionts. Examination of the relationship between the sponge Dysidea herbacea and the blue-gre en alga Oscillatoria spongeliae has revealed that the polychlorinated amino-acid derivatives are localized in and presumably produced by O. spongeliae. Preliminary research on lithistid sponges suggests that th e cyclic peptides found in these sponges may be produced by filamentou s micro-organisms that are found in great abundance within the sponge tissues.