Cellular and subcellular localization of uranium in the crab Carcinus maenas: a microanalytical study

Uranium experimental intoxications were performed on the shore crab Carcinus maenas (L.) using either food (Mytilus edulis) or water pathway contamination. Cellular level investigations performed by secondary ion emission microanalysis show that gill and hindgut epithelia, and hepatopancreas (=digestive gland) R cells are the main sites of uranium concentration. Subcellular level investigations performed by electron probe X ray microanalysis show that intra- and extracellular spherocrystals (=calcium phosphate spherules) are the main target organelles which store uranium; moreover, uranium phosphate microgranules are detected within gill cuticle. A small fraction of the metal is accumulated via food in hepatopancreas spherocrystals, relative to that accumulated from sea water in gill and hindgut spherocrystals and in gill cuticle microgranules. The spherocrystals which are extruded out of the cells and the cuticle which is shed at the ecdysis appear to play a fundamental part in uranium detoxication processes.