IMPROVED VISUALIZATION OF F-ACTIN IN THE GREEN-ALGA ACETABULARIA BY MICROWAVE-ACCELERATED FIXATION AND SIMULTANEOUS FITC-PHALLOIDIN STAINING

By employing a new procedure we have been able to visualize a highly i ntense actin cytoskeleton in the unicellular green alga Acetabularia a cetabulum Silva. The protocol described in this study involves microwa ve-accelerated simultaneous permeabilization with 10% dimethyl sulphox ide, fixation with 1% glutaraldehyde and incubation with 0.5 mu M fluo rescein-isothiocyanate-conjugated Phalloidin. Comparison of the images of the actin cytoskeleton of the stalk, as visualized by methods used previously, with those obtained in our own experiments shows that the actin filaments were preserved completely in an excellent condition. The required time for each procedure could be reduced from 12 h for th e most commonly used immunofluorescence technique to 35 min. Moreover, it has been possible to observe the actin filament system of hair who rls, rhizoid and tip. Previously, the actin cytoskeleton of these part s of the cell could not be visualized by conventional techniques. It i s shown that each region of the cell - stalk, tip, rhizoid and side br anches - displays characteristic degrees of actin bundling and regular ity of actin alignment.