Quantitative fluorescent live cell imaging of intracellular Ca2+ and H+ ions in malaria parasites

Light microscopy plays an important role in cell biology and has been instrumental in the description of the living world. Fluorescent probes and new advances in microscopic techniques have revolutionized the application, enabling real time investigation of biological processes in 3D living cells using physiological conditions. Current applications of live cell imaging may include quantification of ion concentrations in cellular compartments, monitoring ion fluxes and signaling events, protein sorting and trafficking processes, as well as protein-protein interactions. Because of its potential, live cell imaging has been widely applied to study the biology and pathophysiology of the human malaria parasite Plasmodium falciparum. Apart from its clinical importance, P. falciparum has fascinated the cell biologist because of its ability to exist and develop within an inert cell: the human erythrocyte. Our understanding of intracellular ion regulation in malaria parasites has been greatly enhanced since the introduction of fluorescence microscopy and live cell imaging. This chapter provides an overview of the various fluorescent molecules available to monitor ion homeostasis in this parasite and outline the techniques used for ion quantification.