1. Volume 107, Issue 4, Pages 846-853 (August 2014)
Quantitation of Malaria Parasite-Erythrocyte Cell-Cell Interactions Using Optical Tweezers 
Alex J. Crick, Michel Theron, Teresa Tiffert, Virgilio L. Lew, Pietro Cicuta, Julian C. Rayner 
Biophysical Journal 
Volume 107, Issue 4, Pages (August 2014)
DOI: /j.bpj
Copyright © 2014 Biophysical Society Terms and Conditions

2. Figure 1
Selected frames taken from Movie S1 in the Supporting Material, showing optical trapping of a freshly released merozoite, with delivery to and invasion of a targeted erythrocyte. (Red arrow) Optical tweezers-directed movement. The merozoite of interest is shown before the application of a trapping force (0 s), upon delivery of the merozoite to a target cell (3 s), during the subsequent invasion process (20 s), and after the postinvasion echinocytosis of the invaded cell (80 s). To see this figure in color, go online.
Biophysical Journal  , DOI: ( /j.bpj )
Copyright © 2014 Biophysical Society Terms and Conditions

3. Figure 2
Selected frames taken from Movie S4 (A) and Movie S5 (B), showing transient local deformations of the erythrocyte membrane, after optical tweezers-induced changes to the contact area between the erythrocyte and an adherent merozoite. (Red arrows) Optical tweezers-directed movements; (green arrows) local membrane deformations surrounding the adherent merozoite. The erythrocyte and attached merozoite are shown before an optical tweezers intervention (0 s), during the application of a force intended to shift the position of the erythrocyte-merozoite interface (2 s), and after the cessation of optical forces, as a spontaneous local membrane deformation is observed in the region of the adhered merozoite (4–6 s). To see this figure in color, go online.
Biophysical Journal  , DOI: ( /j.bpj )
Copyright © 2014 Biophysical Society Terms and Conditions

4. Figure 3
Selected frames taken from Movie S2 (A) and Movie S3 (B), showing optical tweezers-induced detachment of a postviable merozoite adhered to two erythrocytes. (Red arrows) Optical tweezers-directed movement. The cell-merozoite-cell chains are shown in a relaxed state, upon stretching in one direction, and upon detachment of the merozoite from one of the erythrocytes. Both erythrocytes are held in optical traps in panel A. In panel B, one of the erythrocytes is fortuitously attached to the cover glass. L is the cell length, and L = L0 + ΔL, where ΔL is the elongation and L0 is the cell length in the relaxed state. The detachment force F = κΔL, where κ is the cell stiffness used from Yoon et al. (11). To see this figure in color, go online.
Biophysical Journal  , DOI: ( /j.bpj )
Copyright © 2014 Biophysical Society Terms and Conditions

5. Figure 4
Investigation of the effects of invasion inhibitors heparin (Hep) and cytochalasin D (CytD) and the enzyme treatment of chymotrypsin (ChyT) on merozoite-erythrocyte adhesion (WT = wild-type). (A) Portion of merozoites from each egress adhering to erythrocytes after making contact via optical tweezers delivery, <3 min postegress (black) or >3 min postegress (gray). Values are mean ± SE over egress events. (B) Tweezer-driven merozoite detachment force measured from erythrocyte elongation. No significant correlation was observed between typical detachment forces at <3 min postegress and >3 min postegress (provided merozoites are capable of attachment), so values are mean ± SE over total detachment events.
Biophysical Journal  , DOI: ( /j.bpj )
Copyright © 2014 Biophysical Society Terms and Conditions