Breaking Free (IMAGE) University of Pennsylvania School of Medicine Caption A P. falciparum parasite exits a host erythrocyte loaded with the calcium concentration indicator. High fluorescence of the calcium indicator indicates increased calcium concentration within the host cell. The image is pseudocolored, tending from black (the lowest calcium concentration), through green and yellow to red (the highest calcium concentration) to indicate relative calcium concentration within the host cell. Increased calcium induces calpain activation at the time of parasite egress, as a consequence of upstream host cell signaling. The nuclei of daughter parasites are stained blue in a diagonal pattern from the upper right to the lower left as the parasites are actively exiting the cell. The host cell is no longer uniformly circular since it has been lysed. This shows a high concentration of calcium within the host cell at the end of the parasite cycle, when the host cell lyses and necessary for host calpain activation and break down of the host cytoskeleton. Credit Doron Greenbaum, Ph.D., Perelman School of Medicine, University of Pennsylvania Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.