Journal of Cell Science, Vol 98, 245-249, Copyright © 1991 by Company of Biologists

Attachment strips: a new type of hemidesmosome-like structure in the protozoon Katablepharis ovalis Skuja

¹ Department of Anatomy and Neurobiology, Colorado State University, Fort Collins, CO 80533, USA
² Department of Biology, Colorado State University, Fort Collins, CO 80523, USA

Katablepharis ovalis Skuja is a free-living unicellular flagellate with a phagocytic mode of nutrition. Each cell has one or two hemidesmosome-like attachment strips consisting of electron-dense ridges that pass through the plasma membrane to end at the inner wall. Each attachment strip occurs over a group of microtubules of the cytoskeleton and, like the cytoskeleton, is oriented along the long axis of the cell. The attachment strips occur only over the medial area of the cell and are not found over the anterior one-third or posterior one-sixth of the cell. The attachment strips appear to function like hemidesmosomes, attaching the cell to the extracellular matrix. However, the attachment strips in Katablepharis do not have the cytoplasmic component of hemidesmosomes, e.g. fibrils and electron-dense plaques. Among unicellular organisms, hemidesmosomes have been previously reported only in trypanosomes, where hemidesmosomes on an expanded flagellum attach the parasite to the cuticle of the alimentary canal of the insect host. The possible relationship between the attachment strips in Katablepharis and the hemidesmosomes in trypanosomes is discussed.

Key words: Katablepharis, attachment strip, trypanosome, hemidesmosome