NEW LIGHT ON THE CELL LOCATION OF AVAROL WITHIN THE SPONGE DYSIDEA-AVARA (DENDROCERATIDA)

Many sponges produce and store secondary metabolites with interesting pharmacological bioactivities. Identification of the cell type(s) resp onsible for the production and/or storage of these compounds may be a crucial step for the future culture and production of these substances if the biosynthesis is not envisageable and the producer organism is rare or coo slow-growing for feasible exploitation. Localisation of th ese cells within the sponge may also contribute to ascertaining the ec ological role of these compounds. The cell type containing the main bi oactive metabolite (avarol) and its derivative avarone in the sponge D ysidea avara has been identified by cell isolation in a density gradie nt and by chromatographic techniques. Preliminary cytological characte risation of the cell types in each particular sponge species under stu dy is required, otherwise the identification of the cells in suspensio ns is inaccurate. In contrast with the findings reported for other spo nge species, the active metabolites of D. avara are not contained with in spherulous cells but within choanocytes that line the chambers of t he aquiferous system. The possible ecological role of avarol is discus sed in the light of its internal position and the biological functions of the cells storing the bioactive compounds.