scholarly journals Loss of endocytic capacity in aging Paramecium. The importance of cytoplasmic organelles.

1976 ◽  
Vol 71 (2) ◽  
pp. 575-588 ◽  
Author(s):  
J Smith-Sonneborn ◽  
S R Rodermel
Keyword(s):  
Excretion Rate ◽  
Formation Rate ◽  
Food Vacuole ◽  
Cellular Aging ◽  
Critical Importance ◽  
Vacuole Formation ◽  
Cytoplasmic Organelles ◽  
Food Vacuoles ◽  
Excretion Rates

Aged cells have significantly fewer food vacuoles and ingest fewer bacteria than young cells. Loss of food vacuoles was explained by a decreasing difference in the food vacuole formation and excretion rates; the formation rate declined more rapidly than the excretion rate, approaching equivalence at 160 fissions, when the proportion of cells with no food vacuoles, in the presence of excess food, abruptly increased. A model for cellular aging is presented in which control of organelle numbers and cyclical interactions between the nucleus and cytoplasm may be of critical importance.

The Effect of the H-Ion Concentration on Protozoa, as Demonstrated by the Rate of Food Vacuole Formation in Colpidium

1931 ◽  
Vol 8 (1) ◽  
pp. 17-29
Author(s):  
SYLVIA M. MILLS
Keyword(s):  
Food Vacuole ◽  
Ion Concentration ◽  
Limiting Factors ◽  
Food Ingestion ◽  
Ciliary Movement ◽  
Vacuole Formation ◽  
Alkaline Side ◽  
Food Vacuoles ◽  
Alkaline Range ◽  
Rate Of Movement

1. The effect exerted by the pH of their medium on Colpidium is determined quantitatively by counting the average number of food vacuoles formed in a given time when Colpidium is supplied with Indian ink. 2. Graphs obtained by plotting the rate of feeding against the pH of the medium show a characteristic depression on the alkaline side of neutrality (pH 7.5-8.5), on a curve which otherwise rises steadily from pH 4.5 to a maximum at pH 6.0, and falls from here gradually through the alkaline range. 3. Methods for measuring the rate of movement of ciliates are described, the most practicable being those in which their galvanotropic and geotropic reactions are used to control the direction of the movement. The effect of changes in the pH of the medium on the rate of movement of Colpidium was found to correspond very closely to the effect of similar pHs on the rate of food ingestion. It is, therefore, suggested that changes in the rate of ciliary movement are largely responsible for changes in the rates of food ingestion. 4. Mucus, produced for food collection, and probably also present in the fluid in which the cilia are working, is shown to have a maximum viscosity at pH 8.0. It is suggested that the depression in the region of pH 8.0, seen in curves representing changes in the rates of feeding and movement with pH, indicate that the viscosity of the fluid in which the cilia are beating is one of the limiting factors in the rate of food ingestion through the range of pH occupied by the depression.

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 .

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.

Feeding in Ciliated Protozoa

1974 ◽  
Vol 15 (2) ◽  
pp. 379-401
Author(s):  
JOHN. A. KLOETZEL
Keyword(s):  
Cell Surface ◽  
Buccal Cavity ◽  
Surface Membrane ◽  
Food Vacuole ◽  
Food Ingestion ◽  
Membrane Flow ◽  
Vacuole Membrane ◽  
Vacuole Formation ◽  
Food Vacuoles ◽  
Lamellar Material

The ciliate Euplotes is able to expend a very large amount of membrane in the formation of food vacuoles. Calculations based on the rate of ingestion of the food organism Tetrahymena indicate that an amount of food vacuole membrane equivalent to approximately 50-150% of the total Euplotes cell surface area can be produced within 5-10 min. An aggregation of osmiophilic, membrane-limited ‘pharyngeal disks’ is found packed in the cytoplasm just beneath the cell surface membrane in the region of the cell mouth and cytopharynx. These disks, which can be seen also in living cells, have average dimensions of 2 µm diameter by 100 nm thickness, and contain tightly packed layers of a thin lamellar material. Electron micrographs have revealed the apparent fusion of the limiting membrane of disks with the cell's plasma membrane at the base of the gullet. The lamellar disk contents are thereby released to the exterior medium in the buccal cavity, where they form a loosely packed layer over the surface membrane. It is postulated that the pharyngeal disks represent a repository of preformed membrane for use in food vacuole formation. The disk contents may also play a role in food ingestion, although this is not well defined at present. The myeloid content of old food vacuoles is very similar to that of nearby disks in the cytoplasm, suggesting that the disks may form by pinching from shrinking food vacuoles during the digestive cycle. Thus a cycle of membrane flow is envisaged, with the pharyngeal disks (1) coalescing with the surface membrane during food vacuole formation, (2) reforming by pinching from these food vacuoles during digestion, and (3) migrating back to the oral region to serve as a membrane store for subsequent food vacuole formation.

scholarly journals Whole-body arginine dimethylation is associated with all-cause mortality in adult renal transplant recipients

Amino Acids ◽  
2021 ◽  
Author(s):  
Adrian Post ◽  
Alexander Bollenbach ◽  
Stephan J. L. Bakker ◽  
Dimitrios Tsikas
Keyword(s):  
Renal Transplant ◽  
Excretion Rate ◽  
Whole Body ◽  
Renal Transplant Recipients ◽  
Transplant Recipients ◽  
Kidney Donors ◽  
Body Protein ◽  
All Cause Mortality ◽  
Arginine Residues ◽  
Excretion Rates

AbstractArginine residues in proteins can be singly or doubly methylated post-translationally. Proteolysis of arginine-methylated proteins provides monomethyl arginine, asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA). ADMA and SDMA are considered cardiovascular risk factors, with the underlying mechanisms being not yet fully understood. SDMA lacks appreciable metabolism and is almost completely eliminated by the kidney, whereas ADMA is extensively metabolized to dimethylamine (DMA), with a minor ADMA fraction of about 10% being excreted unchanged in the urine. Urinary DMA and ADMA are useful measures of whole-body asymmetric arginine-dimethylation, while urinary SDMA serves as a whole-body measure of symmetric arginine-dimethylation. In renal transplant recipients (RTR), we previously found that higher plasma ADMA concentrations and lower urinary ADMA and SDMA concentrations were associated with a higher risk of all-cause mortality. Yet, in this RTR collective, no data were available for urinary DMA. For the present study, we additionally measured the excretion rate of DMA in 24-h collected urine samples of the RTR and of healthy kidney donors in the cohort, with the aim to quantitate whole-body asymmetric (ADMA, DMA) and symmetric (SDMA) arginine-dimethylation. We found that lower DMA excretion rates were associated with higher all-cause mortality, yet not with cardiovascular mortality. In the healthy donors, kidney donation was associated with considerable decreases in ADMA (by − 39%, P < 0.0001) and SDMA (by − 21%, P < 0.0001) excretion rates, yet there was no significant change in DMA (by − 9%, P = 0.226) excretion rate. Our results suggest that protein-arginine dimethylation is altered in RTR compared to healthy kidney donors and that it is pronouncedly shifted from symmetric to asymmetric arginine-dimethylation, with whole-body protein-arginine dimethylation being almost unaffected.

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.

Urinary 5-HIAA Excretion is not Increased in Patients with Head and Neck Paragangliomas

2012 ◽  
Vol 27 (2) ◽  
pp. 160-163 ◽  
Author(s):  
Leonie T. Van Hulsteijn ◽  
Nicolette Van Duinen ◽  
Johannes A. Romijn ◽  
Johannes W.A. Smit ◽  
Eleonora P.M. Corssmit
Keyword(s):  
Urinary Excretion ◽  
Head And Neck ◽  
Reference Range ◽  
Excretion Rate ◽  
Case Reports ◽  
Catecholamine Excess ◽  
Hydroxyindoleacetic Acid ◽  
Excretion Rates ◽  
Almost All ◽  
Head And Neck Paragangliomas

Background Case reports have documented carcinoid-like features in head and neck paragangliomas (HNPGLs), which, in addition to catecholamine storing granules, may also contain granules with serotonin. Serotonin is metabolized to 5-hydroxyindoleacetic acid (5-HIAA). Aim To assess the urinary excretion rates of 5-HIAA and catecholamines in HNPGL patients. Methods In 114 consecutive HNPGL patients, normetanephrine, metanephrine, norepinephrine, epinephrine, VMA, dopamine, 3-methoxytyramine and 5-HIAA excretion rates were measured in two 24-hour urinary samples. Increased excretion rates were defined as an increase of the average hormone excretion rate of 2 urine samples above the reference range. In all patients with catecholamine excess, intrathoracic and abdominal paragangliomas were excluded by 123I-MIBG scintigraphy, MRI and/or CT. Genetic screening for mutations in genes of the succinate dehydrogenase (SDH) family was performed. Results Mean urinary 5-HIAA excretion rate was 14±9 μmol/24 hours (reference range 10–44 μmol/24 hours). Urinary 5-HIAA excretion was slightly increased in only 1 patient (48 μmol/24 hours). None of the 50 patients (44%) with increased urinary excretion rates of catecholamines and/or their metabolites had elevated 5-HIAA excretion. Conclusion Urinary 5-HIAA excretion is within the normal reference range in almost all HNPGL patients. Therefore, this parameter has no clinical relevance in the routine clinical assessment of HNPGL patients.

scholarly journals Urinary excretion of amino acids and their advanced glycation end-products (AGEs) in adult kidney transplant recipients with emphasis on lysine: furosine excretion is associated with cardiovascular and all-cause mortality

Amino Acids ◽  
2021 ◽  
Author(s):  
Svetlana Baskal ◽  
Adrian Post ◽  
Daan Kremer ◽  
Alexander Bollenbach ◽  
Stephan J. L. Bakker ◽  
...  
Keyword(s):  
Amino Acids ◽  
Urinary Excretion ◽  
Excretion Rate ◽  
Transplant Recipients ◽  
Kidney Transplant Recipients ◽  
Advanced Glycation ◽  
Glycation End Products ◽  
End Products ◽  
All Cause Mortality ◽  
Excretion Rates

AbstractArginine (Arg) and lysine (Lys) moieties of proteins undergo various post-translational modifications (PTM) including enzymatic NG- and Nε-methylation and non-enzymatic NG- and Nε-glycation. In a large cohort of stable kidney transplant recipients (KTR, n = 686), high plasma and low urinary concentrations of asymmetric dimethylarginine (ADMA), an abundant PTM metabolite of Arg, were associated with cardiovascular and all-cause mortality. Thus, the prediction of the same biomarker regarding mortality may depend on the biological sample. In another large cohort of stable KTR (n = 555), higher plasma concentrations of Nε-carboxymethyl-lysine (CML) and Nε-carboxyethyl-lysine (CEL), two advanced glycation end-products (AGEs) of Lys, were associated with higher cardiovascular mortality. Yet, the associations of urinary AGEs with mortality are unknown. In the present study, we measured 24 h urinary excretion of Lys, CML, and furosine in 630 KTR and 41 healthy kidney donors before and after donation. Our result indicate that lower urinary CML and lower furosine excretion rates are associated with higher mortality in KTR, thus resembling the associations of ADMA. Lower furosine excretion rates were also associated with higher cardiovascular mortality. The 24 h urinary excretion rate of amino acids and their metabolites decreased post-donation (varying as little as − 24% for CEL, and as much as − 62% for ADMA). For most amino acids, the excretion rate was lower in KTR than in donors pre-donation [except for S-(1-carboxyethyl)-l-cysteine (CEC) and NG-carboxyethylarginine (CEA)]. Simultaneous GC–MS measurement of free amino acids, their PTM metabolites and AGEs in urine is a non-invasive approach in kidney transplantation.

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.

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