Berlin 2008 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 18: Biomaterials

BP 18.1: Vortrag

Mittwoch, 27. Februar 2008, 16:00–16:15, PC 203

The isopod exoskeleton: A model to study formation and function of amorphous calcium carbonate in calcified tissues — •Sabine Hild and Andreas Ziegler — Central Facility for Electron Microscopy; University of Ulm, Germany

The mineralized exoskeleton (cuticle) of crustaceans is subjected to periodic molting in which it is periodically decalcified and shed. A new larger cuticle, synthesized before shedding, is mineralized after every molt. These processes cause spatial and temporal variations of the mineral distribution. Thus, the cuticle is an excellent model to study mineralization processes of calcified tissues. The mineral composition of the cuticle of the land living crustacean Porcellio scaber (Isopoda) was examined using Micro-Raman spectroscopy. It was shown that Calcite is restricted to the outer area of the cuticle, whereas amorphous calcium carbonate (ACC) is localized in the middle having only little overlap with the calcite layer. In biological systems ACC is thought to be a precursor phase for crystalline modifications and, because of its high solubility, it is beneficial for temporary calcium carbonate storage. In order to better understand the formation and function of ACC, changes in the distribution and content of mineral phase were monitored during natural and in-vitro decalcification. It was shown that the protective outer calcite layer is shed away during each molt, while ACC is recycled to quickly re-establish the protective calcite layer in the new cuticle. The addition detection of magnesium and phosphate derivates suggests that they assist ACC stabilization.