An improved method for the production of Neurospora crassa spheroplasts and a new method for measuring transport in fragile cells

Scarborough, Gene A.; Schulte, Thomas

doi:10.1016/0003-2697(74)90410-2

Cited by 10 publications

(2 citation statements)

References 15 publications

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“…It was observed that glucose transport (both the initial velocity and the time course in the considered interval of 30 min) by spheroplasts (as measured by the Ficoll centrifugation assay, Figure 6A) and by intact cells (as measured by the filtration assay, Figure 6B) was similar in the absence and presence of insulin. This suggests that the Ficoll centrifugation assay is a valid method for determinating transport in fragile cells such as yeast spheroplasts and confirms previous findings obtained with Neurospora crassa (56). In spheroplasts, insulin (1 µM) did, neither at the beginning nor after 30 min of incubation with glucose (100 mM), affect the initial glucose transport velocity (Figure 6A).…”

Section: Insulin Stimulates Oxidative and Nonoxidative Glucose Metabo...supporting

confidence: 90%

Insulin Signaling in the Yeast Saccharomyces cerevisiae. 1. Stimulation of Glucose Metabolism and Snf1 Kinase by Human Insulin

Müller¹,

Rouveyre²,

Crecelius³

et al. 1998

Biochemistry

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Effects of human insulin on glucose metabolism in the yeast Saccharomyces cerevisiae were studied in this report. Under two conditions of growth limitation (glucose-grown cells during transition to stationary phase or spheroplasts during incubation in synthetic glucose medium), human insulin (10 and 1 microM, respectively) enhanced glycogen accumulation and glycogen synthase activity by 40-60% compared to control cells. Glycogen phosphorylase activity was also increased under the same conditions, but this stimulation was diminished by 35-45% in insulin-treated compared to control cells. Thus, under growth limitation, insulin causes glycogen phosphorylase and glycogen synthase to become more sensitive to inactivation and activation, respectively. In glucose-induced spheroplasts, insulin (1 microM), in addition to glycogen accumulation, led to about 2-fold increases of the rates of ethanol production and glucose oxidation compared to control cells, and the maximal concentration of hexose 6-phosphate was increased by 30-40%. In contrast, glucose transport as well as the levels of the allosteric regulators, fructose 2,6-bisphosphate and cAMP, were not altered at all. Snf1 kinase is assumed to be involved in the regulation of glycogen metabolism in yeast, although it does not seem to be modulated directly by the glucose concentration. Snf1 kinase activity was elevated 5-10-fold in response to insulin both during glucose induction of yeast spheroplasts and during transition to stationary phase of glucose-grown cells. We conclude that Saccharomyces cerevisiae and insulin-sensitive mammalian cells share some parts of the signaling cascades regulating oxidative and nonoxidative glucose metabolism in response to glucose and insulin.

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Section: Insulin Stimulates Oxidative and Nonoxidative Glucose Metabo...supporting

confidence: 90%

Insulin Signaling in the Yeast Saccharomyces cerevisiae. 1. Stimulation of Glucose Metabolism and Snf1 Kinase by Human Insulin

Müller¹,

Rouveyre²,

Crecelius³

et al. 1998

Biochemistry

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“…sl cells grown ovemnight in SeM were harvested by centrifugation, washed three times with SM, and suspended gently in SM plus 2 mg of inulin per ml to a concentration of about 20 mg (dry weight) per ml. A 4-ml volume of this suspension was then layered over an ice-cold solution of 10% Ficoll in SM plus 114C Jcarboxyl-inulin and centrifuged immediately, thus approximating the conditions of the Ficoll transport assay (11). The tubes were decanted, weighed, and dried to constant weight, and the pellets were suspended in water.…”

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confidence: 99%

Characterization of the glucose transport systems in Neurospora crassa sl

Schulte¹,

Scarborough²

1975

J Bacteriol

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Neurospora crassa si, a mutant that lacks a rigid cell wall, exhibits transport systems for glucose similar to those of wild-type strain 1A. When the organism is grown in a medium containing 50 mM glucose as the carbon source, glucose is transported primarily by a glucose-facilitated diffusion system (Glu I). When it is grown in a medium with little or no glucose present, a glucose active transport system (Glu II) is expressed. Both of these systems are similar kinetically to those in the wild type. Significant differences do exist between strains sl and 1A with respect to genetic regulation of the glucose active transport system.

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Isolation and ultrastructural identification of membranes from the fungusGilbertella persicaria

1982

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An improved method for the production of Neurospora crassa spheroplasts and a new method for measuring transport in fragile cells

Cited by 10 publications

References 15 publications

Insulin Signaling in the Yeast Saccharomyces cerevisiae. 1. Stimulation of Glucose Metabolism and Snf1 Kinase by Human Insulin

Insulin Signaling in the Yeast Saccharomyces cerevisiae. 1. Stimulation of Glucose Metabolism and Snf1 Kinase by Human Insulin

Characterization of the glucose transport systems in Neurospora crassa sl

Isolation and ultrastructural identification of membranes from the fungusGilbertella persicaria

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