Role Of Symbiotic Microorganisms In The Biosynthesis Of Sponge
Thursday, September 18th, 2008Marine plants and animals are well known to have developed highly specific relationships with numerous microorganisms (Jensen & Fenical 1994). Sponges, perhaps to a greater extent than any other marine invertebrates, harbor extraneous organisms on their surfaces, in their canal systems, and in the intercellular matrix which constitutes a large part of the body. The volume of bacteria in some species can reach 40% of the total cellular content (Vacelet & Donadey 1977; Wilkinson 1978). The question of the role of these microorganisms in the synthesis of compounds of biological interest is currently the subject of intensive research efforts. We have underlined the difficulties encountered in total synthesis of complicated metabolites such as halichondrins and spongistatins, and the possibility of finding cultivable microorganisms is of considerable interest for development of bioactive molecules. Many examples bolster this hypothesis; the first one was okadaic acid, first isolated from the sponge Halichondria okadai (Kadota, 1922) (Tachibana et al. 1981) as the main cytotoxic compound of the extract, and later demonstrated as the toxin responsible for the intoxications due to the marine dinoflagellates (Prorocentrum lima Dodge, 1975, Dinophysis fortii (Pavillard, 1916) concentrated in a variety of filter feeders. Okadaic acid (Fig. 10) is a selective inhibitor of alkaline phosphatase PPA2, allowing this product to be used as a probe for the study of basic cellular phosphorylation processes. (more…)
