Observations of protoplasmic behavior and motile protoplasmic fibrils in Cytochalasin B treatedNitella rhizoid

Summary

At the concentration of 3–6 μg/ml, Cytochalasin B completely inhibits the protoplasmic streaming in theNitella rhizoid within 10 to 25 minutes. Under the influence of the chemical, behavior of the endoplasm leading to the complete inhibition suggests, as proposed by earlier investigators, that the motive force of the streaming is generated at the boundary between the ectoplasm and the endoplasm. Before the complete inhibition, the chemical causes formation of numerous motile looped and linear fibrils, both of which were similar to those observed by earlier investigators in mechanically disturbed or isolated protoplasm and, in rare cases, in intact cells. The inhibition eventually results in the formation of stationary structures: thicker looped and linear fibrils, and polygonal protoplasmic fragments. Several investigators already inferred that these fibrillar structures were made of microfilaments. This suggests that, at least in theNitella rhizoid, Cytochalasin B probably did not drastically alter the microfilaments, the proposed morphological entities of the force generation in the protoplasmic streaming.