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Figure 2 | Malaria Journal

Figure 2

From: Cytoplasmic free Ca2+ is essential for multiple steps in malaria parasite egress from infected erythrocytes

Figure 2

Free Ca2+content and free Ca2+kinetics within infected cells labelled with a ratio-metric calcium probe Fura Red AM. Cells were labelled with Fura Red AM (5 μM) and monitored at 37°C in medium supplemented with 40 μM probenecid. A. Fluorescence and DIC images of labelled schizont, four images on left; parasite egress from the same schizont captured in all three channels, four images on right. Circle indicates an area of interest selected for analysis of fluorescence in the two ratio-metric channels. Bar = 5 μm. B. Free calcium content in infected cells for three different stages of parasite maturation: early trophozoites, late trophozoite and pre-egress schizonts. Cells were labelled with ratio-metric probe Fura Red AM (5 μM), and monitored at 37°C in the medium supplemented with 40 μM probebecid. Number of analysed cells: early trophozoites – 80, late trophozoites – 60, schizonts – 10. [Ca2+] estimation described in the Methods. C. Rate of calcium increase observed in the three different stages of parasite maturation described in B using the same labelling protocol. Number of analysed cells: early trophozoites – 25, late trophozoites – 60, schizonts – 10. Data presented as a mean ± SEM; significance evaluated using a paired t-test. A statistically significant differences (*) with P < 0.01 was found between early and late trophozoites. D. Representative time courses for the calcium increases observed in early trophozoite (filled circles) and late trophozoite (open circles). E. Time courses for the calcium increases observed in three pre-egress schizonts (circles filled with black, light gray or dark gray colour for each cell). Note that the ratio could plateau prior to egress (black circles curve).

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