Roles of the actin cytoskeleton on dormancy of Dietyostelium discoideum spores

ummary: In dormant spores of the cellular slime mold, Dietyostelium discoideum, half of actin molecules were tyrosine-phosphorylated and actin rods appeared. The high levels of the actin phosphorylation may cause a static state of vesicle transport and concern in maintaining spore dormancy. The dephosphorylation is required for spore germination, indicating that the pathway locates on upstream of the signal transduction for the germination. Since the dephosphorylation depends on uptake of D-glucose and energy production through its consumption, vesicle transport necessary to the germination may rely upon the transport and metabolism of glucose, similarly to the secretion of insulin from pancreatic β-cells. Actin rods were composed of tubules twice thicker than F-actin. It is first found that actin molecules construct tubules. The rods, that may maintain capsule-like shape of spores, seem to be a reservoir for actin-meshwork reconstructed in swollen spores. Thus actin cytoskeleton has crucial roles on regulating spore dormancy in Dictyostelium.