Figure 1.

Characteristic membrane-fluctuation time traces tracked at an arbitrary (real-space) point in the equatorial profile of RBCs (both global variations in the cell radius (cell swelling) and net displacements of the cell center (cell translation) have been subtracted from the data). The data correspond to RBCs with a discocyte shape (dys) at different activity states, as shown in the micrographs (left). (A) A healthy flicker (dys_h) upon cytoskeleton activity. (B and C) Passive cases (h-scale magnified by a factor of 2 with respect to (A)) included drugged RBCs (dys_d) after ATP depletion in PBS(−) buffer (B) and cells fixed with glutaraldehyde (dys_f) (C). Although most RBCs in the passive conditions appeared as nonfluctuating speckled echinocytes, some retained their discocyte shape and continued to fluctuate (dys_d and dys_f). The normalized histograms at right represent the probability distributions of the membrane displacements averaged over all the points in the equatorial profile (σ_h is the standard deviation). The line envelopes correspond to the normal distribution. To see this figure in color, go online.