Penicillin amidohydrolase productivity of locally isolated bacterial species

Penicillin amidohydrolase productivity of four locally isolated bacterial species is described. Organisms were identified asEscherichia coli, Pseudomonas aeruginosa, Sarcina lutea andBacillus megaterium. Highest enzyme productivity of 3.2 U/mL with a corresponding dry cell mass of 4.5 g/L was recorded fromS. lutea.     

Fatty acid metabolism in human lymphocytes. I. Time-course changes in fatty acid composition and membrane fluidity during blastic transformation of peripheral blood lymphocytes

The time-course changes in fatty acid composition of human T-lymphocytes during blastic transformation were analysed, as well as the variations in membrane fluidity determined by fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH), using a fluorescence-activated cell sorter. The more important changes observed, in activated relative to quiescent cells, started after 24 h and consisted in an increase in the proportion of oleic (18:1(n - 9)), docosapentaenoic (22:5(n - 3)) and docosahexaenoic (22:6(n - 3)) acids and a decrease in that of linoleic (18:2(n - 6)) and arachidonic (20:4(n - 6)) acids. This represented a relative increase of 26% for 18:1, 56% for 22:5 and 84% for 22:6 in peripheral blood mononuclear cells (PBMC) and 35%, 182% and 94%, respectively, in purified T-lymphocytes, both activated for 72 h. The decrease in n - 6 fatty acids was of 42% for 18:2 and 14% for 20:4 in PBMC and 30% and 19%, respectively, for 72 h. The decrease in n - 6 fatty acids was of 42% for 18:2 and 14% for 20:4 in PBMC and 30% and phosphatidylethanolamine) rather than neutral lipids. The 18:1/18:0 ratio increased greatly in major cell phospholipids. The proportion of 20:4, 22:5 and 22:6 in phosphatidylinositol was not significantly altered after 72 h of activation. The molar ratio cholesterol/phospholipids was reduced in 72-h-activated lymphocytes (0.29) compared to quiescent cells (0.5). On the other hand, the stimulation of human T-lymphocytes caused a significant decrease in the order parameter (S) of DPH, according to the observed changes in lipid composition. After 72 h in culture, the S value for quiescent and stimulated T-lymphocytes was 0.530 and 0.326, respectively. In conclusion, the blastic transformation of human T-lymphocytes is associated with changes in lipid composition which modify the physical properties of their membranes. These modifications could modulate, in turn, the activity of membrane proteins implicated in the process of blastic transformation.     

Brain glucose bisphosphatase requires inosine monophosphate

Glucose bisphosphate phosphatase has been partially purified from the cytosol of mouse brain. Enzyme activity required Mg2+ and a heat-stable cofactor. The activator was present in boiled extracts of mouse brain mitochondrial-nuclear fraction, of red blood cells, or of rabbit muscle. The chemical properties of the activator are consistent with its identification as inosine monophosphate (IMP), including its mobility in a high pressure liquid chromatography (HPLC) system capable of resolving all of the biologically important mononucleotides. A large number of other biologically important compounds were not effective, including AMP, cAMP, cGMP, and UMP, GMP, purified by HPLC, (50 or 74 microM), gave a rate about 35% of that obtained with IMP (5 microM). The enzyme was separated completely from phosphoglucomutase and significantly from glucose bisphosphate synthase. The products of the reaction are glucose-P and Pi. Fructose bisphosphate at 500 microM inhibited only 40% in the presence of 20 microM glucose bisphosphate. The activation by IMP follows hyperbolic kinetics with an apparent Ka of 5 microM in the presence of 12 microM glucose bisphosphate. The apparent Km of glucose bisphosphate was 10 microM in the presence of 50 microM IMP. There was no inhibition by 5 or 50 microM AMP or ADP. The possible regulatory importance of glucose bisphosphate in carbohydrate metabolism and the significance of the regulation of the phosphatase by the nucleotide are discussed.     

Effect of diet on the weight of brown adipose tissue in rodents

Interscapular brown adipose tissue (BAT) weighed more in rats given access to a solution of sucrose in addition to a nutritionally complete basal diet than in rats eating only a basal diet. This incremental effect of drinking sucrose solution occurs across a variety of dietary conditions. In the first experiment, rats were fed diets containing either 9%, 18%, 27% or 36% casein. Rats given access to a sucrose solution had significantly larger brown fat pads than controls when the diets contained 9 or 18% casein, but not when diets contained either 27% or 36% casein. The second experiment examined the weight of brown adipose tissue as a function of the type of protein and the percentage of fat in the diet. Animals given a sucrose solution had significantly more BAT than animals not given sucrose. Neither the type of protein (casein or soy protein) nor the percentage of fat (14.5% or 36.4%) in the diet influenced the weight of BAT. Animals given access to either a sucrose solution or a glucose solution had significantly heavier BAT than animals given access to a fructose solution, granulated sucrose or water.     

Acetylcholine receptors in normal and denervated rat diaphragm muscle. II. Comparison of junctional and extrajunctional receptors.

Acetylcholine (ACh) receptors have been purified separately from normal rat diaphragm muscle (junctional receptors) and from extrajunctional regions of denervated diaphragm (extrajunctional receptors) in order to compare their properties. The toxin-receptor complexes of the two receptors were indistinguishable by gel filtration and by zone sedimentation in sucrose gradients, and showed identical precipitation curves with rabbit antiserum to the eel ACh receptor. Both toxin-receptor complexes bind concanavalin A and are therefore probably glycoproteins. Low concentrations of d-tubocuratine (dTC) were more effective in decreasing the rate of toxin binding to junctional than to extrajunctional receptors. The apparent dissociation constant for dTC binding to the junctional receptor was 4.5 X 10 minus 8 M, whereas the value for the extrajunctional receptor was 5.5 X 10 minus 7 M. When the complexes were analyzed by isoelectric focusing, the junctional complex focused at approximately 0.15 pH unit lower than the extrajunctional complex. This result was also found with crude preparations of receptor. We conclude that junctional and extrajunctional receptors are similar but distinct molecules. The properties of receptors present in neonatal diaphragm muscle were also examined and found to be similar to those of receptors in denervated muscle, as shown by dTC inhibition and isoelectric focusing.     

The effect of different anamnesis during ontogeny on higher nervous activity in rats.

The consequences of malnutrition, experimental experience and sensory deprivation during early postnatal life were investigated in adult rats. The higher nervous activity of experimental animals was evaluated by means of a battery of tests (exploratory activity, avoidance reaction, preference of a small chamber and a water maze). Rats were divided into 5 groups, i. e. control, trained (with previous experimental experience), light deprived, malnourished naive (12-14 animals in the litter) and malnourished trained. From experimental data obtained it may be concluded that the level of nutrition as well as sensory deprivation or additional stimulation during development are important factors the influence of which persists and modifies the somatic development and the higher nervous activity in adult animals. Light deprived and malnourished rats showed retarded somatic development and worse parameters of higher nervous activity. The difference between groups could be altered by augmented stimulation. Previous experimental experience and intensive handling seems to be an important factor which influences the higher nervous activity of experimental animals.     

Regeneration of plantlets from embryogenic suspension cultures of pickling cucumber (Cucumis Sativus L. CV. Endeavor)

Summary Procedures have been developed for the initiation and long-term maintenance of embryogenic suspension cultures of pickling cucumber (Cucumis sativus) cultivar Endeavor and for the regeneration of normal plantlets. Embryogenic calluses from petiole explants plated on Murashige and Skoog (MS) medium with 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzylaminopurine (BA), both at 5μM, were used to initiate the embryogenic suspension cultures. Among various growth regulator combinations evaluated for initiation and maintenance of these suspension cultures, only MS medium with 2,4-D and BA, both at 1μM, produced cultures that were yellow, friable, and still regenerable after repeated subculture (every two wk) over a 3- to 15-mo. period. The effects of various concentrations of auxin and cytokinin in the plating medium, the addition of AgNO₃, and various plating procedures were also evaluated. The highest frequency of regeneration of shoots and plantlets was achieved by plating aggregates onto filter paper overlaid on MS medium with naphthalene acetic acid (NAA)/BA at a concentration of 2:1 or 1:1μM. The addition of activated charcoal (0.5%) or AgNO₃ (30μM) in the plating medium did not enhance the frequency of plantlet regeneration. The highest frequency of normal-appearing plantlets recovered was 42 to 46% per petri dish. The procedures described in this study can be used to increase plantlet recovery from individual embryogenic calluses of pickling cucumber.