Mutants of Tetrahymena thermophila with temperature sensitive food vacuole formation

1979 ◽  
Vol 124 (2) ◽  
pp. 317-327 ◽  
Author(s):  
Peter B. Suhr-Jessen ◽  
Eduardo Orias
Keyword(s):  
Tetrahymena Thermophila ◽  
Food Vacuole ◽  
Temperature Sensitive ◽  
Vacuole Formation

scholarly journals ADF/Cofilin Is Not Essential but Is Critically Important for Actin Activities during Phagocytosis in Tetrahymena thermophila

2013 ◽  
Vol 12 (8) ◽  
pp. 1080-1086 ◽  
Author(s):  
Nanami Shiozaki ◽  
Kentaro Nakano ◽  
Yasuharu Kushida ◽  
Taro Q. P. Noguchi ◽  
Taro Q. P. Uyeda ◽  
...  
Keyword(s):  
Tetrahymena Thermophila ◽  
Food Vacuole ◽  
Content Type ◽  
Vacuole Formation ◽  
Future Studies ◽  
Cellular Events ◽  
Food Vacuoles

ABSTRACT ADF/cofilin is a highly conserved actin-modulating protein. Reorganization of the actin cytoskeleton in vivo through severing and depolymerizing of F-actin by this protein is essential for various cellular events, such as endocytosis, phagocytosis, cytokinesis, and cell migration. We show that in the ciliate Tetrahymena thermophila , the ADF/cofilin homologue Adf73p associates with actin on nascent food vacuoles. Overexpression of Adf73p disrupted the proper localization of actin and inhibited the formation of food vacuoles. In vitro , recombinant Adf73p promoted the depolymerization of filaments made of T. thermophila actin (Act1p). Knockout cells lacking the ADF73 gene are viable but grow extremely slowly and have a severely decreased rate of food vacuole formation. Knockout cells have abnormal aggregates of actin in the cytoplasm. Surprisingly, unlike the case in animals and yeasts, in Tetrahymena , ADF/cofilin is not required for cytokinesis. Thus, the Tetrahymena model shows promise for future studies of the role of ADF/cofilin in vivo .

scholarly journals MUTANTS OF TETRAHYMENA THERMOPHILA WITH TEMPERATURE-SENSITIVE FOOD VACUOLE FORMATION. I. ISOLATION AND GENETIC CHARACTERIZATION

Genetics ◽  
1979 ◽  
Vol 92 (4) ◽  
pp. 1061-1077
Author(s):  
Peter B Suhr-Jessen ◽  
Eduardo Orias
Keyword(s):  
Tetrahymena Thermophila ◽  
Germ Line ◽  
Complementation Group ◽  
Food Vacuole ◽  
Temperature Sensitive ◽  
Genetic Dissection ◽  
Food Vacuoles ◽  
Per Se ◽  
Oral Development

ABSTRACT Germ-line mutants have been isolated in Tetrahymena thermophila that have recessive, temperature-sensitive defects in phagocytosis. Nitrosoguanidine-mutagenized cells were induced to undergo cytogamy, and clones were isolated that were unable to form food vacuoles after two days of growth at 39°. Most of the mutants belong to a single complementation group, designated vacA. They have defects in oral development—not in phagocytosis per se—that are undetectable under light microscopy. One fertile mutant, phenotypically indistinguishable from the vacA group, has its vac mutation(s) restricted to the macronucleus, and it is a heterokaryon for two other markers. This clone probably resulted from a failure of the two gametic nuclei to fuse after nor,mal exchange. Two additional mutants were studied, but their sterility prevented a full genetic analysis. One of these clones has a rudimentary oral apparatus and defective contractile vacuole pores; both defects may be determined by the same mutation. The other clone has a structurally normal oral apparatus and may be defective in phagocytosis per se.——The induction and characterization of germ-line mutations that affect oral development open the way for the genetic dissection of the morphogenesis of a complex eukaryotic organelle, and make available additional useful mutants for the study of nutrition and transmembrane active transport.

Dual capacity for nutrient uptake in Tetrahymena. V. Utilization of amino acids and proteins

1979 ◽  
Vol 36 (1) ◽  
pp. 343-353
Author(s):  
E. Orias ◽  
L. Rasmussen
Keyword(s):  
Amino Acids ◽  
Plasma Membrane ◽  
Tetrahymena Thermophila ◽  
Amino Acid Uptake ◽  
Food Vacuole ◽  
Transport Systems ◽  
Acid Uptake ◽  
Vacuole Formation ◽  
Carrier Mediated Transport ◽  
Food Vacuoles

We investigated the relative contributions of phagocytosis and plasma membrane transport to the uptake of amino acids and a protein (egg albumin) in amounts which allow Tetrahymena thermophila to grow and multiply. We used a mutant capable of indefinite growth without food vacuole formation (phagocytosis) and its wild type (phagocytosis-competent) isogenic parental strain. Our results suggest that phagocytosis is not required for free amino acid uptake, most or all of which can be attributed to carrier-mediated transport systems, apparently located on the plasma membrane. In contrast, phagocytosis is required for utilization of the protein. Proteins can supply required amino acids in amounts sufficient for growth only when food vacuoles are formed. We conclude that Tetrahymena thermophila either possesses no endocytic mechanisms at the cell surface other than food vacuole formation or, if it does, these putative mechanisms are not capable of nutritionally meaningful rates of protein uptake.

Exocytosis, endocytosis and membrane recycling in Tetrahymena thermophila

1988 ◽  
Vol 89 (4) ◽  
pp. 515-520
Author(s):  
ARNO TIEDTKE ◽  
PETER HÜNSELER ◽  
JORGE FLORIN-CHRISTENSEN ◽  
MONICA FLORIN-CHRISTENSEN
Keyword(s):  
Cell Lines ◽  
Tetrahymena Thermophila ◽  
Food Vacuole ◽  
Secondary Effect ◽  
Membrane Recycling ◽  
Acid Hydrolase ◽  
Wild Type ◽  
Acid Hydrolases ◽  
Vacuole Formation ◽  
Food Vacuoles

Mutant and wild-type cell lines of Tetrahymena thermophila were used to investigate a possible connection between acid hydrolase secretion and the major processes through which membranes are recycled in this ciliated protozoon. These processes consist of food vacuole formation (endocytosis), and food vacuole egestion and mucocyst release (both exocytosis). We have found that a mutant (MS-1, see−) blocked in hydrolase secretion is not blocked in either food vacuole formation or egestion and that it has normal mucocyst exocytosis. Another line of experiments with wild-type cells showed also that hydrolase secretion and endocytosis are independent of each other. Thus, sucrose (0.1m) did not interfere with hydrolase secretion, but blocked food vacuole formation. Furthermore, release of acid hydrolases was selectively stimulated by dibucaine without any effect on food vacuole egestion. Finally, exocytosis of mucocysts could occur without simultaneous release of acid hydrolases, as when cells were exposed to (0.15M-NaCl, which evokes a massive secretory response of mucocysts. Our results demonstrate that formation and egestion of food vacuoles and exocytosis of mucocysts are unrelated to secretion of acid hydrolases. Furthermore, they suggest that secretion of acid hydrolases is not a secondary effect of membrane recycling through these processes.

Directionality of microtubule assembly: an in vivo study with the ciliate Tetrahymena

1978 ◽  
Vol 33 (1) ◽  
pp. 227-234
Author(s):  
S.F. Ng
Keyword(s):  
Tetrahymena Thermophila ◽  
Recessive Gene ◽  
Microtubule Assembly ◽  
In Vivo Study ◽  
Temperature Sensitive ◽  
Sensitive Mutant ◽  
Posterior Portion ◽  
Temperature Sensitive Mutant

A temperature-sensitive mutant homozygous for the recessive gene molb in Tetrahymena thermophila offers opportunity for studying the direction of microtubule assembly in vivo. At 39 degrees C the mutant fails to divide properly; the 2 daughter animals remain attached and bend over each other. As revealed by protargol staining, the bending results in acute turning and breaking of some of the longitudinal microtubular bands close and parallel to the surface. Hence, 2 broken microtubular ends are available for study of the problem of directionality of microtubule assembly, by assessing which of the 2 ends regenerates. In most cases the posterior portion of the longitudinal microtubular band regenerates. The present study hence supports the conclusion based on in vitro observation in other systems that microtubule assembly is predominantly unidirectional.

Cytochalasin B: Aspects of Phagocytosis in Nutrient Uptake in Tetrahymena

1974 ◽  
Vol 15 (2) ◽  
pp. 403-406
Author(s):  
ELSE K. HOFFMANN ◽  
L. RASMUSSEN ◽  
E. ZEUTHEN
Keyword(s):  
Nutrient Uptake ◽  
Nutrient Medium ◽  
Cytochalasin B ◽  
Tetrahymena Pyriformis ◽  
Food Vacuole ◽  
Vacuole Formation ◽  
Proteose Peptone ◽  
High Concentrations

Cytochalasin B (37 µg per ml) reduces the rate of food vacuole formation, i.e. the rate of phagocytosis, in Tetrahymena pyriformis. Cytochalasin B in this concentration suppresses multiplication rates in a nutrient medium consisting of 2 % proteose peptone, but multiplication is unaffected if this medium is supplemented with glucose and high concentrations of nucleosides. Thus nutrients in high concentrations circumvent the necessity for phagocytosis in Tetrahymena.

scholarly journals Isolation and phenotypic characterization of Tetrahymena thermophila size mutants: the relationship between cell size and regulation of DNA content

1984 ◽  
Vol 67 (1) ◽  
pp. 203-215
Author(s):  
H.M. Seyfert ◽  
H. Hipke ◽  
W. Schmidt
Keyword(s):  
Cell Size ◽  
Cell Lines ◽  
Tetrahymena Thermophila ◽  
Small Cells ◽  
Chemical Mutagenesis ◽  
Phenotypic Characterization ◽  
Temperature Sensitive ◽  
Average Cell ◽  
Average Cell Volume

Temperature-sensitive size mutants of the ciliate Tetrahymena thermophila were selected following chemical mutagenesis. Phenotypical characteristics are given for seven cell lines, which have a range of average cell volumes from 8000 microns 3 to more than 100 000 microns 3. wild-type Tetrahymena cells have an average cell volume of 15 000 microns 3. Two of the mutagenized cell lines have comparatively small cells at 29 degrees C but normal cells at 37 degrees C; whereas the other five lines are normal at 29 degrees C but large at 37 degrees C. While the small cells are poor growers, the large cells grow excellently at 37 degrees C. Measurements of DNA, RNA and protein contents indicate a significant correlation between all parameters and cell size. However, since the cells tolerate considerably different concentrations of each class of macromolecules, the amount of any of these macromolecules cannot be tightly controlled by cell size.

Infection and maintenance of Holospora obtusa, a macronucleus-specific bacterium of the ciliate Paramecium caudatum

1985 ◽  
Vol 76 (1) ◽  
pp. 179-187
Author(s):  
M. Fujishima ◽  
M. Fujita
Keyword(s):  
Host Cell ◽  
Nuclear Membrane ◽  
Species Complex ◽  
Tetrahymena Thermophila ◽  
Food Vacuole ◽  
Paramecium Caudatum ◽  
Negative Bacterium ◽  
Gram Negative ◽  
Blepharisma Japonicum ◽  
Infection Experiments

The gram-negative bacterium Holospora obtusa is a macronucleus-specific symbiont of the ciliate Paramecium caudatum, which invades the host cell via a food vacuole, infects its macronucleus and grows exclusively in the nucleus. From infection experiments, we showed that a property of the macronucleus that is necessary for it to be recognized and infected by H. obtusa is commonly provided by P. caudatum, P. multimicronucleatum and 14 species of the P. aurelia complex, but not by P. jenningsi, P. bursaria, P. trichium, P. duboscqui, Didinium nasutum, Blepharisma japonicum, Pseudourostyla levis, seven species of Euplotes or Tetrahymena thermophila. Furthermore, it was also shown that the bacteria that infect the macronuclei of P. multimicronucleatum and the P. aurelia species complex always disappear from the nuclei within 5 days and the infected bacteria are maintained stably in the host nuclei in only 13 out of 22 strains of P. caudatum. The results indicate that the species specificity of the habitat of H. obtusa is not simply a matter of its ability to penetrate the host nuclear membrane but depends on unknown factors that exist only in certain strains of P. caudatum.

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