The undulating membrane of trichomonads — the structure and immunolabelling of its cytoskeleton

Abstract

Summary The undulating membrane (UM) of several genera of Trichomonadidae (Trichomitus, Trichomonas, Tetratrichomonas, Pentatrichomonas, Trichomitopsis, Pentatrichomonoides) and also of Monocercomonadidae (Pseudotrichomonas, Ditrichomonas) is composed of a fold of the plasma membrane on the cell body to which the recurrent flagellum adheres via the cell coat. This UM contains a cytoskeletal structure or marginal lamella composed of a basal plate about 25 nm thick, bearing barbs. After treatment by Triton, the UM cytoskeleton shows a lattice like ultrastructure. That structure consists of intersecting “lines” with a 13 nm periodicity. A MAb raised in mice immunized with Trichomitus batrachorum cytoskeletons decorates the UM of Trichomitus by IF and labels a protein band of 25 kDa on immunoblots. Another MAb decorates the UM of Tetratrichomonas gallinarum, but the 2 MAbs do not cross react. When the MAb is used in immunogold staining it labels the UM of Trichomitus in transverse and longitudinal sections and in wholemount cytoskeletons as well. The results are discussed and compared to similar structures in the trichomonad lineage and to other groups of organisms.