ELECTROPHORETIC AND IMMUNOLOGICAL CHARACT ERIZATION OF SHELL SOLUBLE MATRICES FROM 2 LIVING PTERIOMORPHID BIVALVES, PINNA-NOBILIS L AND PINCTADA-MARGARITIFERA (L)

In the Bivalves, shell formation is influenced by a soluble organic ma trix, closely linked to the mineral phase. Pinna nobilis and Pinctada margaritifera have a bi-layered shell, characterized by an outer prism atic calcitic microstructure and an inner nacreous aragonitic one. A c omparison of electrophoretic and immunological properties of the solub le matrices extracted from these layers is performed. Electrophoresis data suggest that great differences exist: the matrices of prisms are rich in acidic polysaccharides and contain discrete proteinaceous comp ounds, especially a major one of 17 kDa, whereas the nacreous material predominantly consists of polydisperse macromolecules. However, the d issimilarities are attenuated by immunological tests (ELISA), indicati ng that an important part of antigenic determinants is common to the t wo microstructures.