Figure 1.
Time-lapse imaging for the rupture of schizont-infected red blood cells.
Images were captured every 0.1 sec with transmitted light for Plasmodium yoelii 17XL (A), P. yoelii 17X1.1 (B), and Plasmodium falciparum 3D7 line (C). The bars represent 5 µm.
Figure 2.
Three phase processes of the red blood cell (RBC) invasion by Plasmodium yoelii.
Time-lapse imaging of RBC invasion was captured every 0.1 sec with transmitted light for P. yoelii 17XL (A), P. yoelii 17X1.1 (B), and Plasmodium falciparum 3D7 line (C). First “Pre-invasion” phase started from the initial attachment between the merozoite (0 second, arrow head) and RBC plasma membrane, followed by the RBC deformation, and apical reorientation of the merozoite (rightmost column of “Pre-invasion” phase). Second “Invasion” phase consisted of the internalization of a merozoite into RBC and a rapid rotary movement of the internalized merozoite (arrow). Final “Echinocytosis” phase was defined as RBC being deformed to spike-like shape. The bars represent 5 µm.
Figure 3.
Kinetic difference in red blood cell (RBC) invasion between Plasmodium species.
The median time for each step are shown as a box plot with whiskers from minimum to maximum. The interquartile range shows as box with the median marked as a horizontal line, minimum and maximum from lower and upper quartile represent error bar. P values were determined using the Mann-Whitney U test. See Table S1 for detail values.
Figure 4.
Morphological change of the Plasmodium yoelii merozoite after released from red blood cell (RBC).
The major axis (A), minor axis (B), longitudinal cross section area (C), and circularity (D) were measured every 10 sec from RBC rupture to pre-invasion for invasive merozoites (n = 9–12). The average and the error representing one standard deviation were plotted in the line charts. Circularity was calculated using the following formula: Circularity = 4πArea/Perimeter2. A value of 1 indicates a perfect circle and the value of 0 indicates an increasingly elongated polygon. See Table S1 for detail values. (E) Time-lapse sequence of merozoite release of P. yoelii 17XL was recorded every 0.1 sec. Arrowhead indicates same invasive merozoite in the sequence and the arrow indicates an attachment of an immature flat elongated oval merozoite. A mature spherical invasive merozoite attached to the RBC and deformed RBC (Pre-invasion) at 180 sec. The bar represents 5 µm.