MICROFILAMENTOUS SEPTAL BELT (FSB) DURING INDUCTION OF CYTOKINESIS IN TRAMETES-VERSICOLOR (L EX FR)

Combined light and electron microscopical investigations, complemented by nuclear displacement experiments, showed that cytokinesis in vegetative hyphae of the basidiomycetous fungus Trametes versicolor is triggered during meta-anaphase. In the course of the trigger stage (duration, 1-2 minutes), cytoplasmic elements are accumulated within the incipient septum region. Morphological peculiarities do not occur during this stage at either the plasmalemma or the cell wall until the end of nuclear division. About 1 minute after separation of the daughter nuclei a peripheral belt of 4- to 7-nm microfilaments (FSB) is laid down within seconds where, a few minutes later, formation of the septal wall begins. Tight associations among the FSB, mitochondria, and microvesicles seem to indicate interactions between microfilaments and membranes and to lead to trapping of these and other cell organelles. Correspondence of the events with many details of animal cytokinesis is obvious. © 1979 Academic Press, Inc. All rights reserved.