Localization of actin in the cortex of Paramecium tetraurelia cells by immuno- and affinity-fluorescence microscopy.
The cortex of the ciliate Paramecium tetraurelia has been examined both with whole cells and with isolated surface complexes (pellicles) for the presence and distribution of actin, using direct fluorescence labeling with antibodies monospecific for Paramecium actin, with DNase I or with heavy meromyosin, all tagged with FITC as a fluorochrome. The results obtained with the three different methods were similar. Actin is concentrated in the cilia and--clearly visible only after deciliation--in the basal bodies. The docking site of secretory vesicles (trichocysts) onto the cell membrane does not display any selective actin content. This does not preclude the interaction with actin at other sites of the trichocysts, since diffuse fluorescence labeling in deeper layers of the cell did not allow us yet to analyze the distribution of actin throughout the cell body. However, our data would preclude any direct involvement of actin at the site of exocytotic membrane fusion proper.
D000199:Actins / Q000032:analysis*; D000818:Animals; D008856:Microscopy, Fluorescence / Q000379:methods*; D010247:Paramecium / Q000166:cytology* / Q000648:ultrastructure
D000199:Actins