Portal de Periódicos da CAPES

Rhizoplast-membrane associations in the flagellate Tetraselmis cordiformisStein (Chlorophyceae) revealed by freeze-etching and thin sections

1979; Elsevier BV; Volume: 122; Issue: 3-4 Linguagem: Inglês

10.1016/s0003-9365(79)80043-3

2213-5553

Horst Robenek, Michael Melkonian,

Plant and Biological Electrophysiology Studies

Summary The two rhizoplasts of Tetraselmis cordiformis are firmly attached to the nuclear envelope and the plasmalemma in addition to their connection with the flagellar apparatus. In the region of contact the freeze-fractured nuclear membrane is indented and partly devoid of nuclear pores. Links are probably mediated via the cross-bars of the rhizoplast at certain specific sites. At the plasma-lemma the contact zone in freeze-fractured cells displays a “ridge” of 5 × 0.4 μm. dimensions. Intramembraneous particle numbers on the E-fracture face are significantly higher in this region than in other parts of the plasmalemma. Variations in certain aspects of rhizoplast ultrastructure and its associations with membranes are discussed in accordance with the proposed contractile function of the rhizoplast. Evidence is presented that shortening preferentially occurs in the proximal region of the rhizoplast near the flagellar apparatus and that the “normal” image of an evenly spaced rhizoplast is probably a fixation artifact.