Septate junction disruption and surface reorganization by non-lethal Ca²⁺ shock

Using potassium pyroantimonate as a Ca²⁺ chelating agent, we have been able to open the belt desmosome that mechanically couples adjacent ciliated lateral (L) gill epithelial cells of freshwater mussels. Subsequent transfer of the mechanically uncoupled epithelia to solutions containing millimolar Ca²⁺ results in dramatic alterations in cell shape and partial disruption and apical reorientation of L cell septate junction. The cells remain viable throughout the procedure as determined by the persistence of ciliary activity, although disruption is accompanied by a separation of neighboring groups of cilia and a switch from metachronal to synchronous L cell ciliary beat co-ordination.