Figure 2.

Locked-in versus dynamic length variation

(A) Sign change test for locked-in flagellar length differences. Each plot shows the length difference between two flagella in one cell, plotted for successive time points. Top example is of a cell showing signal reversal, indicating that neither flagellum is consistently longer than the other.

(B) Genetic test for locked-in flagellar differences using ptx1 mutant that eliminates functional asymmetry between flagella. (Red) ptx1 mutant cells (black); wild type. Average length in ptx1 mutants is reduced compared with wild type, but uncorrelated variation is larger than in wild type (η²_int = 0.013 [95% confidence interval 0.007–0.02] for ptx1 versus η²_int = 0.007 [95% confidence interval 0.005–0.01] for wt), indicating the PTX1-dependent biochemical asymmetry in the two flagella is not a substantial source of uncorrelated variation.

(C) Correlated variation has a dynamic component. Scatterplot shows fluctuations in the lengths of both flagella in a cell during a 10-min time-step. Each point represents data from one cell at one time interval. ΔL1 and ΔL2 indicate the change in length of the two flagella in a cell during a single 10-min time interval, plotted one against the other.