On the cover: Cytochalasins are widely used as inhibitors for actin-based processes. Numerous forms of cytochalasins have been identified and although they share common biological activity, they may differ considerably in potency.
In this issue, Foissner and Wasteneys (pp. 585-597) investigated the effects of cytochalasins A, B, C, D, E, H, J and dihydrocytochalasin B in an ideal experimental system for cell motility, the giant internodal cells of the characean alga Nitella pseudoflabellata. Cytochalasin D and H were found to be most suited for fast and reversible inhibition of actin-based motility although subcortical actin filament bundles remained intact at the time of streaming cessation and disassembled only after one to several days' treatment. All of the cytochalasins induced reorganization of the more labile cortical actin filaments into actin patches, swirling clusters or short rods. Latrunculins A and B arrested streaming only after disrupting the subcortical actin bundles, a process requiring relatively high concentrations and very long treatment periods of more than one day, and worked synergistically with cytochalasins.
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