Figure 9.

Model of A. gossypii SPB and cMT arrays emanating at SPBs. (A) Model of three nuclei with independent cMT arrays in a hypha. The most apical nucleus has close contact to the growing tip via its short cMTs. Loss of cMTs will increase the distance between the first nucleus and the tip as shown in Figure 3. The two other nuclei are connected with the hyphal cortex via short cMTs and most likely also long cMTs. Growth and shrinkage of these cMTs provides pushing and pulling forces for short-range nuclear oscillations. The most likely pulling force in the direction of a single short cortex-connected cMT was discussed in Figure 4A. Nuclear bypassing is a long-range movement and is very likely achieved by pulling forces of a long cMT when the cortex connection of short cMTs is reduced or absent. Nuclei cannot oscillate or bypass in hyphae lacking short and long cMTs as shown in Figure 3. Nuclei with mutant SPBs able to emanate mainly/only long cMTs cannot oscillate but are still able to bypass other nuclei (unpublished observations). (B) Schematic representation of an A. gossypii SPB and associated microtubules.