Gal Mor Khalifa, Department of Structural Biology, Weizmann Institute of Science , Rehovot
Foraminifera are marine protozoans which construct an outer protective clacitic shell. The process by which the foraminifera cell incorporates calcium ions form the sea water and deposit them as a calcite mineral in its shell wall constitute large part of the calcium carbonate formation in the ocean. We study the process of the foraminifera shell formation by labeling calcium in the sea water with the fluorescent calcium indicator, clacein, and following its incorporation and distribution in the foraminifera cytoplasm and finally its incorporation into the shell wall. This is a freeze fractured, calcein labeled foraminifera cell observed in confocal fluorescent microscope under cryo conditions. Labeled with calcein we see the outline of the shell wall and the distribution of calcium in the cytoplasm. The red signal comes from auto fluorescence of algal symbionts living inside the cytoplasm of the foraminifera.