Fig. 3. Effect of calcium on microneme secretion by T. gondii. Western blot analysis of secretion by parasites treated with agents to chelate extracellular or intracellular calcium. Chelation of intracellular calcium with BAPTA-AM completely blocked secretion. Cellular MIC2 (cMIC2) forms present in dilutions of parasite pellets (cell stds) migrate at a larger size compared to the secreted form of MIC2 (sMIC2) found in supernatants. Ethanol combined with incubation at 37°C was used to stimulate secretion in all the samples. Unstimulated cells that were not treated with ethanol or raised to 37°C were used as a negative control. Unstimulated actin provided a control for inadvertent cell lysis in the experiment. Example shown is a representative blot from three independent experiments with similar results.