Mechanism Of Glucose Uptake Research Articles

Glucose uptake of Cytophaga johnsonae studied in batch and chemostat culture

The influence of different physiological states on the glucose uptake and mineralization by Cytophaga johnsonae, a freshwater isolate, was examined in batch and chemostat cultures. At different growth rates under glucose limitation in chemostat cultures, different uptake patterns for 14C labeled glucose were observed. In batch culture and at high growth rates the glucose uptake potential showed a higher maximum velocity and a much lower substrate affinity than at lower growth rates. These findings and the results of short-term labeling patterns could be explained by two different glucose uptake mechanisms which enable the strain to grow efficiently both at high and low substrate concentrations. Substrate specificity studies showed that a structural change of the C-2 atom of the glucose molecule was tolerated by both systems. The consequences of these results for the ecophysiological classification of the Cytophaga group and for the operation of continuous cultures are discussed.

Effects of 5-methoxyindole-2-carboxylic acid on growth, glucose uptake and glycogen content in Tetrahymena pyriformis GL

1. 1. Low concentrations of 5-methoxyindole-2-carboxylic acid (MICA) considerably prolonged the log phase in cultures of Tetrahymena pyriformis GL. 2. 2. Glucose uptake by cells in the stationary phase was inhibited by approx 50% after 45 min exposure to 27.25 μg/ml of MICA. 3. 3. MICA (0.54 μg/ml) reduced the cellular content of glycogen and increased the glycogen phosphorylase activity in vivo. 4. 4. MICA, however, showed neither activating nor inhibitory effects on this enzyme activity in vitro. 5. 5. It may be thought that MICA does not interfere directly with the mechanism of glucose uptake. but MICA has influence on the metabolic control systems.

Permeation and Membrane Transport in Animal Parasites: On the Mechanism of Glucose Uptake by Hymenolepis diminuta

In recent studies (Phifer, 1959, 1960), it has been demonstrated that the tapeworm, Hymenolepis diminuta, takes up glucose against a concentration gradient by processes having characteristics which suggest coupling to energy metabolism. Observations on the effects of innate physiological factors also supported this hypothesis. Since it appears that a catalytic mechanism is involved in the movement of glucose from the medium into the worm, it seemed important to test some of the hypotheses which have been put forward to account for glucose absorption in other tissues. The present inquiry may be broken down into three categories relating to (1) the effect of addition of an energy source on glucose uptake; (2) stereospecificity of the uptake of glucose; (3) the nature of systems involved.

Action of muscular work on transfer of sugars across cell barriers; comparison with action of insulin.

Action of muscular work on transfer of sugars across cell barriers; comparison with action of insulin.