Figure 5:

Energetic analysis to identify hypotheses that are consistent with experimental results of PT extrusion kinematics in varying external viscosities. Each row (A-E) shows calculations based on the five different hypotheses, and the three columns show the calculation for total energy requirement, peak pressure requirement, and peak power requirement, respectively. As we described in Figure 4C and in the Methods section, we expect mere changes in surrounding viscosity should not change the ability of the spore to produce necessary pressure or power to initiate the germination process, and it should not change the total amount of energy released during the firing process. We thus computed the total energy requirement (left column), peak pressure requirement (middle column), and the peak power requirement (right column) of each PT firing event shown in Figure 4A. We tested if changing surrounding viscosity causes significant changes in the total energy requirement, peak pressure requirement or peak power requirement using Kruskal–Wallis test, for the five different hypotheses (five rows, A to E). If the statistical testing reveals a p-value which is significant (near or below 0.05), the hypothesis should be identified as contradicting experimental results, because changing surrounding viscosity should not cause changes in the ability of spores to produce energy or pressure. Only the p-values which are significant or near-significant are shown. The data shown here is calculated assuming a cytoplasmic viscosity of 0.05 Pa-sec, and a zero boundary slip. The effect of ambiguity in cytoplasmic viscosity and slip length of the boundaries are discussed in Table 1 and 2. Under these assumptions, Model 1 and Model 3 are the two hypotheses that are least likely to be true. Also note that for the other three hypotheses (Model 2, Model 4, and Model 5), the total energy requirement is roughly 10⁻¹¹J, the peak pressure requirement is roughly 60–300 atm, and the peak power requirement is roughly 10⁻¹⁰W.