Figure 7.

Grid of calculated anisotropy patterns of hourglass septin assemblies in top view as a function of GFP dipole orientations. A single value pair {θ, ϕ} defines the prevailing dipole orientations of septin-GFP constructs in an hourglass. Each hourglass in the grid shows the calculated pattern of anisotropies, which are represented by short magenta lines whose lengths are proportional to the fluorescence ratio and whose orientations are parallel to the polarization that exhibits the strongest fluorescence. The center position of each hourglass in the grid indicates the {θ, ϕ} pair used in the calculation. Patterns for θ or ϕ values larger than 90° would repeat the patterns shown. The red rectangle corresponds to {θ, ϕ} values that lead to anisotropy patterns that are compatible with measured patterns of the Cdc12-conGFP3 construct, whereas CDC12-conGFP4 results are compatible with {θ, ϕ} values associated with the green strip. The latter patterns have two characteristic features: 1), the anisotropy is aligned horizontally throughput the hourglass, and 2), near the left and right edge of the hourglass the anisotropy value goes to zero (ratio = 1). For the calculation, paired filaments were assumed to run parallel to the hourglass axis.