Glucose utilization by suspensions of Tetrahymena pyriformis

Waithe, William I.

doi:10.1016/0014-4827(64)90075-8

Cited by 13 publications

(1 citation statement)

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“…Of numerous cells measured, the smallest were almost round, approximately 15 to 20 ,m in diameter. The largest cells, pyriform, were 30 by 70, 28.7 by 71.4, 28 by 70, 30 by 78, 32 by 78, and 17.5 by 80.5 ,m. Dividing cells, attached pairs, were 21 by 38 and 21 by 39, 23 by 36 and 23 by 36, and 26 by 47 and 26 by 37 ,m. The measurements of some of the predominant sizes, mostly pyriform, were 30 by 62, 25 by 61, 27 by 57, and 26 by 46 ,um.…”

Section: Methodsmentioning

confidence: 99%

Elutriation and Coulter Counts of Tetrahymena pyriformis Grown in Peanut and Cottonseed Meal Media

Teunisson

1971

Applied Microbiology

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Growth of Tetrahymena pyriformis W has been used to evaluate nutritional quality of peanut and cottonseed meals. An efficient elutriation method is described for separating cells of this organism from particulate matter left in the substrate (enriched with basal medium) after 4 days of incubation. After elutriation the cells can be counted with a Coulter counter by using calibration procedures which are presented. Elutriation and Coulter counting provide a rapid and efficient method of measuring the growth response of T. pyriformis W. Utility of the method is demonstrated by agreement between Coulter counts and visual counts of the cells and by demonstration of a linear response of cell numbers to substrate nitrogen. A method of evaluating the effects of processing on the nutritive quality of protein products more rapid than the 28-day rat feeding test should have great utility. The growth of Tetrahymena pyri-1oX final concentration, membrane-filtered (Millipore Corp., Bedford, Mass.), and stored frozen in sterile, screw-cap bottles. All other stock solutions (except 878

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Section: Methodsmentioning

confidence: 99%

Elutriation and Coulter Counts of Tetrahymena pyriformis Grown in Peanut and Cottonseed Meal Media

Teunisson

1971

Applied Microbiology

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Effect of tolbutamide on the metabolism of Tetrahymena

Blum

Connett

Porter

1974

Journal Cellular Physiology

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Tolbutamide partially inhibited the growth but increased the glycogen content of Tetmhymena pyriformis in logarithmically growing cultures. Tolbutamide slightly increased 14C02 production from [ 1-14C] and [6-14C] glucose and [2-14C] pyruvate, but had little effect on the oxidation of [1-14C] acetate when any of these substrates were added to the proteose-peptone medium in which the cells had been grown. Measurement of 14C02 production from [1-14C] and [2-14C] -glyoxylate showed that this substrate was primarily oxidized via the glyoxylate cycle, with little if any oxidation occurring via the peroxisomal glyoxylate oxidase. Addition of tolbutamide inhibited the glyoxylate cycle as indicated by a marked reduction in label appearing in COZ and in glycogen from labeled acetate.In control cells, addition of acetate strongly inhibited the oxidation of [2-14C] -pyruvate whereas addition of pyruvate had little effect on the oxidation of [1-14C] -acetate. Acetate was more effective than pyruvate in preventing the growth inhibitory and glycogen-increasing effects of tolbutamide. The data suggest that one effect of tolbutamide may be to interfere with the transfer of isocitrate and acetyl CoA across mitochondria1 membranes.Sulfonylureas have been used extensively in the treatment of mild adult onset diabetes, but despite much work their mechanisms of action remain obscure. It was originally believed that the hypoglycemic effect of tolbutamide was due to a direct action on liver metabolism, but later work focused on the effect of this drug on insulin release (Yalow, Black, Villazon and Berson, '60). More recently attention has again centered on extrapancreatic sites of action since the long term effects of tolbutamide cannot be accounted for in terms of insulin release alone (Feldman and Lebovitz, '69). Since glucose utilization by Tetrahymena pyriformis is not sensitive to insulin (Waithe, '64), it appeared that this ciliated protozoan might be a useful cell for studying the metabolic actions of tolbutamide in the absence of complex hormonal controls. In addition, the report (Shenoy and McLaughlan, '59) that tolbutamide inhibited the growth of Tetrahymena under conditions of limiting pantothenic acid supply suggested that this drug affected the metabolism of Tetrahymena. Since their report, however, no further studies of the effect of tolbutamide on Tetrahymena have been published.We found that in addition to reducing the growth rate tolbutamide, at concentrations comparable to those found in tissues during therapy (Feldman and Lebovitz, '69), increased the glycogen content of Tetrahymena. We have therefore undertaken an investigation of the effect of tolbutamide on many aspects of intermediate metabolism in Tetrahymena. In this paper we compare the oxidation of labelled glucose, acetate, pyruvate, and glyoxylate and the rate of incorporation of label from these substrates into glycogen in control cells and in tolbutamide-treated cells. In addition, we have measured the effect of tolbutamide on the level of activit...

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