Figure 2. Measuring fission yeast cell wall elastic modulus.

A) Single fission yeast cells with similar cell length were pushed into chambers smaller than the cells. Chambers with decreasing elastic moduli E_ch (from left to right) are shown. Bars = 5μm. B) Illustration of the method used to compute chamber deformation. (Left) The initial chamber diameter, D, is measured on the surrounding chambers (precision better than 5%) and the deformation, d, is measured along the force axis. (Right) The force from the chamber deformation equilibrates the buckling force. Because this buckling force is proportional to the cell wall surface modulus, this method allows for a direct calculation of the cell wall surface modulus at the single cell level. Bar = 5μm. C) Plot of the chamber deformation as a function of the inverse of the scaled chamber elastic modulus (E*, see eq. 4) obtained from 155 single cells. Different symbols correspond to different chamber elastic moduli, as shown in the legend. The fit used is parabolic to account for second order saturations at larger deformation. The imprecision in the measurement is found to be higher than the scattering of the data around the proposed fit. The strain is NM11.