title: Okadaic acid, an apoptogenic toxin for symbiotic/parasitic annelids in the demosponge Suberites domuncula.
abstract: The role of okadaic acid (OA) in the defense system of the marine demosponge Suberites domuncula against symbiotic/parasitic annelids was examined. Bacteria within the mesohyl produced okadaic acid at concentrations between 32 ng/g and 58 ng/g of tissue (wet weight). By immunocytochemical methods and by use of antibodies against OA, we showed that the toxin was intracellularly stored in vesicles. Western blotting experiments demonstrated that OA also existed bound to a protein with a molecular weight of 35,000 which was tentatively identified as a galectin (by application of antigalectin antibodies). Annelids that are found in S. domuncula undergo apoptotic cell death. OA is one candidate inducer molecule of this process, since this toxin accumulated in these symbionts/parasites. Furthermore, we identified the cDNA encoding the multifunctional prosurvival molecule BAG-1 in S. domuncula; it undergoes strong expression in the presence of the annelid. Our data suggest that sponges use toxins (here, OA) produced from bacteria to eliminate metazoan symbionts/parasites by apoptosis.
authors.affiliation: Institut für Physiologische Chemie, Abteilung Angewandte Molekularbiologie, Universität, Duesbergweg 6, 55099 Mainz, Germany.
authors.forename: Heinz C
authors.initials: HC
authors.lastname: Schröder
authors.forename: Hans J
authors.initials: HJ
authors.lastname: Breter
authors.forename: Ernesto
authors.initials: E
authors.lastname: Fattorusso
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ushijima
authors.forename: Matthias
authors.initials: M
authors.lastname: Wiens
authors.forename: Renate
authors.initials: R
authors.lastname: Steffen
authors.forename: Renato
authors.initials: R
authors.lastname: Batel
authors.forename: Werner E G
authors.initials: WE
authors.lastname: Müller
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000845:Annelida / Q000187:drug effects* / Q000502:physiology; D017209:Apoptosis / Q000187:drug effects*; D001419:Bacteria / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D019319:Okadaic Acid / Q000378:metabolism / Q000494:pharmacology*; D047233:Suberites / Q000378:metabolism / Q000382:microbiology* / Q000469:parasitology*; D013559:Symbiosis; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: C091732:BCL2-associated athanogene 1 protein; D004268:DNA-Binding Proteins; D014157:Transcription Factors; D019319:Okadaic Acid