Journal of Cell Science, Vol 10, 563-583, Copyright © 1972 by Company of Biologists

Submitted on June 21, 1971

Movement, Fine Structure, and Fusion of Pseudopods of an Enclosed Amoeba, Difflugiella Sp

¹ Department of Anatomy, Harvard Medical School, Boston, Massachusetts 02115, and the Armed Forces Institute of Pathology, Washington, D.C. 20305, U.S.A.

In Difflugiella sp., strain F-20, a small amoeba enclosed in a flexible mantle, pseudopods extended through a mouth or aperture and seemed to function only for movement and feeding. Pseudopods from different cells fused on contact and cell clumps shared common pseudopods and moved in a co-ordinated way. During locomotion, pseudopods or pseudopod complexes usually exhibited an activity cycle of 3 phases: anterior extension with the tip firmly adhering; stable hold as other pseudopods advanced; and flaccid posterior retraction. While distal adhesive tips advanced, proximal unattached parts of pseudopods simultaneously shortened as the cell body advanced.

Microtubules were numerous in pseudopods within the mouth but extended for only 1-2 µm into pseudopods up to 20-30 µm long. Microfilaments were present where pseudopods adhered to the substratum, to the mantle, or to bacteria and were also associated with pinocytotic invaginations. Pseudopod ground plasm was either reticulate or amorphous; no axial rods or aligned filaments related to pseudopod rigidity were seen.

Simultaneous pseudopod adhesion, extension, and proximal shortening apparently account for locomotion or cell body translation of Difflugiella. While some similarities to other amoeboid systems were noted, the need for detailed studies on different types of organisms or cells is emphasized.

Note:

Present address.