2-Deoxy-D-galactose metabolism in ascites hepatoma cells results in phosphate trapping and glycolysis inhibition.

The metabolism of 2-deoxy-D-galactose has been studied in AS-30D rat ascites hepatoma cells in suspension. Using 2-deoxy-D-(1-14C)galactose and an alkaline ethanol deproteinization procedure, the quantitatively identified metabolites included 2-deoxy-D-galactose 1-phosphate comprising 99.3%, and UDP-2-deoxy-D-galactose and UDP-2-deoxy-D-glucose, together amounting to 0.4% of the total metabolites. After incubation for 5 h in the presence of 2-deoxy-D-galactose (1 mmo1/1), the content of 2-deoxy-D-galactose 1-phosphate reached 35 mmo1x(kg cells)-1. The rate of phosphorylation of 2-deoxy-D-galactose was rapid during the first 30 min and decreased to approximately 20% of this rate during the subsequent hours. The rapid trapping of Pi in the form of 2-deoxy-D-galactose 1-phosphate resulted in a depression of free intracellular Pi in spite of a concomitant increase in net 32Pi uptake from the medium and a decrease of ATP and other 5'-nucleotides. The rates of glucose utilization and lactate production were depressed by more than 80% in the presence of 2-deoxy-D-galactose (1 mmo1/1). Interruption of Pi trapping by removal of 2-deoxy-D-galactose from the medium reversed the depressions of Pi and ATP and resulted in a rapid but incomplete relief of glycolysis inhibition. Crossover analysis of glycolytic intermediates indicated an inhibition at the 6-phosphofructokinase step. The depression of glucose utilization may be mediated by the increased level of glucose 6-phosphate, a potent inhibitor of hexokinase. An additional inhibitory effect of a metabolite of 2-deoxy-D-galactose at the 6-phosphofructokinase step was indicated by crossover analysis after reversal of Pi and ATP depressions in the presence of a high intracellular content of 2-deoxy-D-glactose 1-phosphate. The quantitative analysis of the metabolites of 2-deoxy-D-galactose demonstrated the predominance of the monophosphate and the negligible formation of UPD derivatives of this sugar analog in AS-30D hepatoma cells. This provides a system for the investigation of a galactose analog as a phosphate-trapping agent in the virtual absence of uridylate trapping.     

DDT induced ethological changes in estuarine fish

Synopsis Experiments were carried out to study the feeding rates of the predator fish Therapon jarbua (Forsk) on mullet juveniles, before and after treatment with DDT. Mullet juveniles treated with a subacute concentration, were refused by the control predators, whereas predators treated with a subacute concentration consumed more mullet juveniles. In the present study crescent perch T. jarbua were exposed to subacute and acute concentrations of DDT, and their behaviour was compared with that of the control predators. There were changes in oriented behaviour and co-ordinated movements, and in feeding, aggression and comfort behaviour of the fish. Inflammation in the gills, and caudal fin serration, were noticed in treated fishes. The findings presented here throw light on fundamental pathways by which pollutants interact with the behaviour of fishes.     

Changes in the ionization equilibrium of erythrocyte suspension under heating]

The effects of ionic strength, urea, calcium and fluorine ions, ouabain and cholinesterase inhibitors on the changes in the ionization equilibrium of an erythrocyte suspension under heating were studied. Proton release by erythrocytes was compared to a release of potassium ions and hemoglobin from the cells. The proton release under heating is mainly determined by the physico--chemical properties of superficial structures of erythrocytes and does not depend on the activity of cholinesterase, ATPase and glycolytic processes.     

Isoproterenol-induced, lymphocyte-dependent hyperplasia of mouse salivary glands--a possible analog of a syngeneic mixed lymphocyte culture in vivo

T-cell phenotype that regulates isoproterenol-induced lymphocyte-dependent hyperplasia of mouse salivary glands and conditions of its activation has been investigated. Stimulated Thy-1 and Ly-1-positive cell populations proliferated in the medium supplemented with both interleukin-1 (IL-1) and interleukin-2 (IL-2). The inhibiting population was Thy-1 and Ly-2-positive, proliferating only in IL-2-containing medium. Both regulatory cell properties and the character of their activation are similar to those of lymphocytes that regulate syngeneic mixed lymphocyte culture. The regularities shown may reflect important processes of cell proliferation regulation in multicellular organisms.     

Infection with Wolbachia does not influence crossing-over in Drosophila melanogaster

The influence of endosymbiotic bacterium Wolbachia on the recombination processes in the sex chromosome of Drosophila melanogaster on the region between white and cut genes has been studied. The analysis of the crossing-over frequency in various variants of strain crossing, infected and noninfected, with bacteria has been carried out. The results have shown the absence of the influence of infection with Wolbachia on the frequency of crossing-over in the studied region of the X chromosome of D. melanogaster.