Unveiling Ca2+ requirements for light acclimation in diatoms

In eukaryotes, calcium (Ca2+) is a key secondary messenger that regulates diverse physiological processes. Abiotic and biotic stress, such as pathogen attacks, osmotic or oxidative stress, result in an increase in cytoplasmic Ca2+ concentration, which empowers an immediate signal transduction pathway. In this contest, in plants, changes in light regimes have been described to generate Ca2+ transients in the cytosol followed by a long lasting wave in the chloroplast. For phytoplanktonic cells, light play a pivotal role on their survival and for the chimeric diatoms (key component of the phytoplankton, originated by a secondary endosymbiosis, in contrast to plants) we suggest an alternative Ca2+ signaling pathways from those identified so far. This proposal aims at unveiling the natural subcellular distribution of Ca2+ in diatoms using synchrotron X-ray fluorescence (SXRF) and to assess the element requirements during light acclimation.