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.

Cell Multiplication in Tetrahymena Cultures after Addition of Particulate Material

1973 ◽  
Vol 12 (1) ◽  
pp. 275-286
Author(s):  
L. RASMUSSEN ◽  
L. MODEWEG-HANSEN
Keyword(s):  
Tetrahymena Pyriformis ◽  
Food Vacuole ◽  
Particulate Material ◽  
Cell Multiplication ◽  
Particulate Suspensions ◽  
Proteose Peptone ◽  
Generation Times ◽  
Food Vacuoles ◽  
Net Charges ◽  
Peptone Broth

We have studied the effects of adding particulate supplements to populations of Tetrahymena pyriformis in 2% sterile-filtered proteose peptone broth which supports cell multiplication poorly (generation times in excess of 40 h). The tested compounds were: heat-sterilized suspensions of egg albumin, nutritionally inert particles of polystyrene, sulphopropyl and quarternary amino-ethyl substituted dextran (in concentrations of 4, 40 and 400 µg per ml). The particles had approximately the same size, but differed in their electric net charges. Particulate suspensions of 40 µg per ml or more greatly improved cell multiplication rates (generation times about 6 h). It is probable that the effect of the particles is to induce formation of food vacuoles without which cell multiplication and growth is very slow. The contribution of the food vacuole to nutrient uptake in Tetrahymena is discussed.

Intracellular distribution of lead in Tetrahymena during continuous exposure to the metal

1979 ◽  
Vol 39 (1) ◽  
pp. 383-396
Author(s):  
J.R. Nilsson
Keyword(s):  
Cell Growth ◽  
Growth Medium ◽  
Food Vacuole ◽  
Continuous Exposure ◽  
Organic Growth ◽  
Food Vacuoles ◽  
Entire Cell ◽  
Membrane Bound ◽  
Lag Period ◽  
High Concentrations

Lead acetate (0.1–0.2%) forms a precipitate with the organic growth medium. The Tetrahymena cells ingest this lead-containing precipitate and cell growth is resumed after a variable lag period. Ingested lead is observed as electron-dense material in food vacuoles. Soon after exposure, cytoplasmic lead (preserved with certain fixation only) is revealed as electron-dense particles in cilia and in a halo around digestive vacuoles. Later the lead particles pervade the entire cell but after the lag period they are confined to membrane-bound spaces. In dilute growth medium, high concentrations of lead inhibit food-vacuole formation and cell growth. Under these conditions lead is deposited in alveoli of the pellicle and is also found in autophagic vacuoles and other membrane-limited structures. The study has revealed that lead enters Tetrahymena through the membrane of digestive vacuoles and through the cell surface. The change in distribution of lead during the lag period indicates that a mechanism is activated for removal of lead into membrane-bound spaces. The final storage of lead seems to be in lysosomes.

Untersuchungen über die Phosphorsäureester-Resistenz und über den Mechanismus der Entwicklung dieser Resistenz bei Tetrahymena pyriformis Gl.

1968 ◽  
Vol 23 (6) ◽  
pp. 829-833
Author(s):  
M. Volm
Keyword(s):  
Oxygen Consumption ◽  
Acid Phosphatase ◽  
Survival Time ◽  
Catalase Activity ◽  
Acid Phosphatase Activity ◽  
Cholinesterase Activity ◽  
Tetrahymena Pyriformis ◽  
Phosphate Esters ◽  
High Concentrations ◽  
Resistant Cells

The effect of 0,0-Diethyl-O-p-nitrophosphate (Paraoxon) on the growth of Tetrahymena in culture was investigated. At all concentrations tested (dilutions 1: 10.000 to 1 million) growth was depressed.After pretreatment with Paraoxon at a dilution of 1:100.000, resistence to the compound developed. Thus 5 days pretreatment increased the survival time in high concentrations of Paraoxon threefold, and 14 days ninefold, when compared with controls. Resistant and non-resistant cells were compared. After 8 days pretreatment oxygen consumption and catalase activity doubled. Acid phosphatase activity doubled following 4 weeks pretreatment and a twofold increase in cholinesterase activity was seen after 8 weeks pretreatment.No specific esterases capable of splitting phosphate esters could be shown in resistant cells.It may be significant that in resistant cells enzymes sensitive to Paraoxon are increased.

Die Bildung von Thymidintriphosphat bei Tetrahymena pyriformis (EHRENBERG) in statistischen und hitzesynchronisierten Kulturen / Formation of Thymidine Triphosphate in statistical and heat synchronized cultures of Tetrahymena pyriformis (EHRENBERG)

1970 ◽  
Vol 25 (5) ◽  
pp. 517-521 ◽  
Author(s):  
Manfred K. Grieshaber ◽  
Franz Duspiva
Keyword(s):  
Heat Treatment ◽  
Enzyme Activity ◽  
Stationary Phase ◽  
Dna Synthesis ◽  
Tetrahymena Pyriformis ◽  
Thymidylate Kinase ◽  
Proteose Peptone ◽  
Thymidine Triphosphate ◽  
Logarithmic Growth ◽  
Synchronized Cultures

The activity of thymidylate kinase is correlated with DNA-synthesis in Tetrahymena. During logarithmic growth it is twice as high as in the stationary phase; in cultures synchronized by heat treatment, the activity of the enzyme increases with the onset of DNA-synthesis. After application of 5 x 10-6 ᴍ Methotrexate, the activity of thymidylate kinase remains unchanged. There is, however, a dramatic increase in enzyme activity when the inhibition of transmethylations is circumvened by adding thymidine and proteose-peptone.

The effects of carbon dioxide on the growth and development of amphibious plants

1969 ◽  
Vol 47 (11) ◽  
pp. 1803-1807 ◽  
Author(s):  
J. Michael Bristow
Keyword(s):  
Carbon Dioxide ◽  
Nutrient Medium ◽  
Growth And Development ◽  
Normal Growth ◽  
Growing Season ◽  
Solid Substrate ◽  
Submerged Plants ◽  
Land Form ◽  
Amphibious Plants ◽  
High Concentrations

When grown in a stream of 5% CO2 in air on a solid substrate, the heterophyllous amphibious species Ranunculus flabellaris and Myriophyllum brasiliense developed many characteristics of the water form. Plants of the same clones grown in 0.03% CO2 exhibited the land form. Submerged plants grew rapidly when 5% CO2 in air was bubbled through the nutrient medium, and exhibited the typical water form, while plants kept in 0.03% CO2 grew poorly, and the small leaves which developed were intermediate in morphology between the land and water forms. These results are similar to those obtained previously with Marsilea. None of these species were able to utilize bicarbonate. The stream from which the Ranunculus used in the experiments was collected contained high concentrations of dissolved free CO2 during part of the growing season. Thus concentrations of free CO2 higher than those in air may be essential for the normal growth and development of submerged amphibious plants.

scholarly journals Glycation of the human erythrocyte glucose transporter in vitro and its functional consequences

1990 ◽  
Vol 268 (3) ◽  
pp. 661-667 ◽  
Author(s):  
P J Bilan ◽  
A Klip
Keyword(s):  
Erythrocyte Membrane ◽  
Human Erythrocyte ◽  
Glucose Transporter ◽  
Cytochalasin B ◽  
Competitive Inhibitor ◽  
Human Erythrocyte Membrane ◽  
Functional Consequences ◽  
High Concentrations ◽  
Erythrocyte Membrane Proteins

Glycation of human erythrocyte membrane proteins was induced by incubation in vitro with high concentrations (80 mM or 200 mM) of D-glucose for 3 or 6 days. The extent of glycation was quantified from the covalent incorporation of 3H by reduction of the glucose glycation products with NaB3H4. For membranes incubated for 3 days with 80 mM-D-glucose, glycation in vitro of Band 4.5 (containing the glucose transporter) was equivalent to 0.11 mol of glucose/mol of glucose transporter, compared with 3H labelling in 3-day-incubated control membranes of 0.055 mol of glucose/mol of glucose transporter. In membranes incubated for 6 days with 200 mM-D-glucose, glycation increased to 0.21 mol of glucose/mol of glucose transporter, whereas the controls without glucose had 0.11 mol of glucose/mol of glucose transporter. Glycation in vitro was accompanied by a fall in the Bmax of binding of [3H]cytochalasin B (a competitive inhibitor of glucose transport), without any change in the binding affinity. The data suggest that glycated glucose transporters have decreased ability to bind cytochalasin B. It is proposed that glycation can alter glucose transporter activity.

scholarly journals On the possible role of serotonin in the regulation of regeneration of cilia.

1980 ◽  
Vol 85 (2) ◽  
pp. 242-247 ◽  
Author(s):  
N Rodríguez ◽  
F L Renaud
Keyword(s):  
Calcium Ions ◽  
Tetrahymena Pyriformis ◽  
Intracellular Concentration ◽  
Causal Relationships ◽  
Serotonin Synthesis ◽  
High Concentrations ◽  
Regulation Of Regeneration

A study was made of the interrelationship of serotonin, cAMP, and calcium ions in the regulation of regeneration of cilia by Tetrahymena pyriformis. All these compounds stimulated the regeneration, whereas a blocker of serotonin synthesis, p-chlorophenylalanine, and a calcium chelator, EGTA, inhibited the process. This inhibition could be overcome by the addition of any of the stimulatory compounds. cAMP was also found to be inhibitory at high concentrations. The intracellular concentration of this nucleotide was found to increase during the regeneration, and this increase occurred precociously in the presence of serotonin. It was concluded that serotonin may regulate ciliary regeneration by a mechanism involving cAMP And calcium ions, but that the causal relationships among these compounds still need to be established.

scholarly journals Factor VIII-induced superaggregation of human platelets

Blood ◽  
1982 ◽  
Vol 60 (6) ◽  
pp. 1359-1369 ◽  
Author(s):  
EP Kirby ◽  
DC Mills ◽  
H Holmsen ◽  
M Russo
Keyword(s):  
Factor Viii ◽  
Cytochalasin B ◽  
Dextran Sulfate ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
Ionophore A23187 ◽  
High Concentrations ◽  
Induced Aggregation ◽  
Very High ◽  
Bovine Factor

Abstract High concentrations of bovine factor VIII cause clumping of platelets into a few very large aggregates. This response is termed superaggregation. It is distinct from factor-VIII-induced agglutination but is also independent of both extracellular calcium ions and platelet energy metabolism. Neither agglutinating lectins nor aggregating agents, including thrombin, ADP, the ionophore A23187, and U46619, a prostaglandin analog, can induce superaggregation, even at very high concentrations. Washed platelets undergo superaggregation, and superaggregation does not increase the amounts of fibrinogen or albumin trapped by agglutinated platelets. It is not inhibited by membrane- stabilizing drugs or by colchicine or cytochalasin-B. Formaldehyde and glutaraldehyde prevent superaggregation without affecting the binding of radiolabeled factor VIII to the platelets. Superaggregated platelets are separated by approximately 50 nm and are not shape-changed or degranulated. In adenosine diphosphate (ADP) induced aggregation, the platelets are distorted and only 30 nm apart. Superaggregation is reversed by dextran sulfate, and the dispersed platelets are still able to respond to ADP. Our observations are consistent with the binding of high molecular weight multimers of bovine factor VIII to more than one receptor on each platelet, with superaggregation occurring through recruitment of additional receptors. This process may be interrupted by protein crosslinking reagents, such as formaldehyde and glutaraldehyde.

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