Corrosion of intracellular granules and cell death

The snail Helix aspersa has large numbers of calcium cells in its hepatopancreas which contain membrane-bound intracellular granules of CaMgP 2 O 7 . These inorganic deposits are the sites of accumulation of a wide variety of cations and act as a detoxification mechanism that traps a number of dietary metals once they have entered the animal. This study concentrates on the mechanism of incorporation of manganese ions into these deposits by using electron microscopy, ultra-low-angle X-ray scattering and extended X-ray absorption spectroscopy. The results show that manganese ions cause a localized corrosion of these intracellular granules with a consequent release of calcium ions. This release appears to overwhelm the calcium-regulatory mechanisms of these cells and leads to their death and subsequent shedding into the lumen of the alimentary tract. The concept of intracellular corrosion is a novel interpretation of a previously unsuspected biochemical lesion.