MEPS 179:297-300 (1999)  -  doi:10.3354/meps179297

Calcium oxalate production in the marine sponge Chondrosia reniformis

Carlo Cerrano1,*, Giorgio Bavestrello2, Attilio Arillo1, Umberto Benatti3, Stefano Bonpadre4, Riccardo Cattaneo-Vietti1, Laura Gaggero1, Marco Giovine3, Luciana Leone4, Gabriella Lucchetti1, Michele Sarà1

1Dipartimento per lo Studio del Territorio e delle sue Risorse dell'Università di Genova, Viale Benedetto XV 5, I-16132 Genova, Italy
2Istituto di Scienze del Mare dell'Università di Ancona, Via Brecce Bianche, I-60131 Ancona, Italy
3Istituto policattedra di Chimica Biologica dell'Università, Viale Benedetto XV 1, I-16132 Genova, Italy
4Dipartimento di Scienze Biomediche dell'Università di Ancona, Via Brecce Bianche, I-60131 Ancona, Italy

ABSTRACT: A constant amount of calcium oxalates, as weddellite and whewellite, has been detected by X ray diffraction analysis in the NaClO resistant fraction of the tissue of the demosponge Chondrosia reniformis. SEM observations showed that oxalate is present on the surface of living sponges, suggesting that the crystals are produced inside and/or on the sponge surface. The output of oxalate crystals through the sponge ectosome represents a significant percentage of sediments collected by sediment traps placed in a C. reniformis population. HPLC analyses allowed the detection of high levels of ascorbic acid in the sponge's tissue; the spontaneous conversion of the ascorbic acid to oxalic acid, well known in plants, may explain the oxalate occurrence. Although the ascorbic acid is involved in the biosynthesis of collagen, the release of ascorbic/oxalic acid through the sponge surface may be utilised to ward off other benthic organisms during competition for space and as an antifeeding mechanism against possible predators.

KEY WORDS: Oxalate · Ascorbic acid · Porifera · Biomineralization

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