The roles of actin cytoskeleton and microtubules for membrane recycling of a food vacuole in Tetrahymena thermophila.
Phagocytosis is a fundamental cellular event for the uptake of nutrients from the environment in several kinds of eukaryote. Most ciliates egest waste and undigested materials in food vacuoles (FVs) through a cytoproct, which is a specific organelle for defecation. It is considered that FV egestion is initiated by fusion between the FV membrane and plasma membrane in a cytoproct and completed with retrieval of the membrane into a cytoplasmic space. In addition, electron microscopy indicated that microfilaments might be involved in the recycling process of the FV membrane in ciliates over 30 years ago; however, there is no conclusive evidence. Here we demonstrated actin organization on FV near a cytoproct in Tetrahymena thermophila by using a marker for a cytoproct. Moreover, it was revealed that cells treated with actin cytoskeletal inhibitor, Latrunculin B, might be suppressed for membrane retrieval in a cytoproct following FV egestion. On the other hand, the actin structures, likely to be the site of membrane retrieval, were frequently observed in the cells treated with cytoplasmic microtubules inhibitor, Nocodazole. We concluded that actin filaments were probably required for recycling of the FV membrane in a cytoproct although the role was not essential for FV egestion. In addition, it was possible that microtubules might be involved in transportation of recycling vesicles of FV coated with F-actin.
Structural Biosciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
Maki
M
Sugita
Kentaro
K
Nakano
Mayuko
M
Sato
Kiminori
K
Toyooka
Osamu
O
Numata
D008841:Actin Cytoskeleton / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D000199:Actins / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D000818:Animals; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology*; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D008870:Microtubules / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D015739:Nocodazole / Q000494:pharmacology; D015388:Organelles / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D012997:Solvents / Q000494:pharmacology; D016808:Tetrahymena thermophila / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D053778:Thiazolidines / Q000494:pharmacology; D050257:Tubulin Modulators / Q000494:pharmacology
D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D012997:Solvents; D053778:Thiazolidines; D050257:Tubulin Modulators; C037068:latrunculin B; D015739:Nocodazole; D004121:Dimethyl Sulfoxide