Higher Relative Activity Research Articles

PATTERNS OF OXIDATIVE ASSIMILATION IN STRAINS OF PSEUDOMONAS AND ACHROMOBACTER.

Tomlinson, Geraldine A. (University of British Columbia, Vancouver, B.C., Canada) and J. J. R. Campbell. Patterns of oxidative assimilation in strains of Pseudomonas and Achromobacter. J. Bacteriol. 86:434-444. 1963.-Oxidative assimilation of glucose-U-C(14) in the absence of added nitrogen was studied by use of washed-cell suspensions of Pseudomonas aeruginosa, P. fluorescens, Achromobacter strain B81, and Achromobacter viscosus (Alcaligenes viscolactis). The suggestion that oxidative assimilation in these organisms is the reincorporation of endogenously produced ammonia by way of alpha-ketoglutarate is tenable. Each of the four organisms accumulated intermediate compounds which acted as pacemakers for the oxidation of glucose. This phenomenon, partly because it ensured the availability of additional ammonia, undoubtedly increased the degree of oxidative assimilation. Products accumulating in the supernatant fluids during glucose oxidation were alpha-ketoglutarate, pyruvate, gluconate, a low molecular weight carbohydrate, and dicarboxylic acids. No two bacteria formed the same products. Assimilation of radioactivity into the cells, which accounted for 12 to 26% of the available C(14), continued as long as an oxidizable substrate was present, and was paralleled by uptake of endogenously produced ammonia. During the early stages of glucose oxidation, compounds of the cold trichloroacetic acid-soluble pool constituted a major portion of the total radioactivity of the cells. The lipid fractions of P. aeruginosa and Achromobacter B81 were also of high relative activity during this time. The labeling of the nucleic acid fractions of all four bacteria increased with time, more radioactivity being found in fractions from the two Achromobacter species than in those from the pseudomonads. At the completion of the experiment, the largest percentage of incorporated radioactivity was present in the protein fractions. One of the organisms, Achromobacter B81, synthesized a high molecular weight carbohydrate material.

The time-lag between magnetic and ionospheric changes

The above time-lag is investigated for summer months (November–February) from summer 1953/1954 to summer 1960/1961. It is found that the 1 day delay reported by Bergh and King (1961) is in fact only predominant during periods of high solar activity and absent during sunspot minimum. A 2 day lag seems to persist throughout the solar cycle but is overshadowed during sunspot maximum by the 1 day delay. The nocturnal behaviour of maximum electron density in the F2-region is studied during a year of high solar activity in relation to the K-indices of the preceding day. A recombinative type of electron removal is found to correlate more consistently with magnetic changes than does an attachment type of removal.

Carboxymethylcellulase and cellopentase activities of electrophoretic fractions of cellulose

Of nine electrophoretically distinct fractions obtained from a fungal cellulase by starch block zone electrophoresis, five were found to be practically identical with respect to relative enzymic activities on cellopentaose and carboxymethylcellulose, three appeared to have somewhat high relative activities on the cellopentaose, and one had a very low relative activity. The fractions also showed distinct and reproducible differences in relationships between amounts of enzyme and amounts of reducing sugar produced with carboxymethylcellulose as the substrate.

The changing pattern of amino acid incorporation in developing mesoderm cells

THE first studies in which autoradiography was used to investigate the sites of amino acid incorporation into early embryonic cells revealed the very high activity of the nucleus and in particular of the nucleolus and the chromatin immediately associated with it [ll, 121. This nuclear incorporation begins at about the time at which other evidence suggests that specific proteins first make an appearance in the embryonic tissues. One is tempted, therefore, to regard the amino acid incorporation as an indication of nuclear activity directly related to the synthesis of proteins whose specificity is controlled by the genes. However, most present theories of protein synthesis in the cell suppose that it takes place primarily in the cytoplasm, where RNA enters importantly into the process and the actual structures at which the synthesis occurs may be the microsomal particles and/or endoplasmic reticulum. It is therefore of some interest to discover whether the high relative activity of the nucleolar apparatus is still a feature of cells at later stages of differentiation, when the process of specific protein synthesis is proceeding much more rapidly than at the early stages previously studied. Accordingly, the pattern of labelling was studied at various stages in the developing amphibian mesoderm, from about the time when the developmental fate of the tissue is first determined to a stage at which the myoblasts are growing rapidly and differentiating into muscle fibres. Axolotl embryos were cultured for one or three hours in 50 per cent Holtfreter solution, with 3 &cc 2-14C-DL-3-phenylalanine (sp. act. 0.826 mc/mM) and 0.1 per cent sulphadiazine, at pH 7 and room temperature. Phenylalanine is a very specific tracer for protein [3]. The stages used were: late yolk plug (stage 12 for Amblysfoma punctatum [7]), closing neural fold (l&19), tail bud (stage 35) and young larva (stage 39940). To permit access of tracer the archenteron was split open in the two younger stages and most of the belly removed under anesthesia from the older stages, but the embryos were quite lively at the end of culturing. Unoperated controls of similar age were almost unlabelled. After a rinse, the embryos were fixed in Smith for

Distribution of phytase in the rat

Phytase activity has been demonstrated to be widely distributed in the rat, the highest activity being found in the intestinal mucosa. The relative distribution of this enzyme parallels closely the known relative distribution of alkaline phosphatase with the exception of brain which exhibits a high phytase activity in relation to its β-glycerophosphatase activity. Mg ++ caused an increase in the phytase activity of crude homogenates from all of the tissues studied, but the degree of activation was not the same for different tissues. Hydrolysis of phytic acid and β-glycerophosphoric acid by intestinal autolyzate was nonadditive and therefore not due to the action of two enzyme systems acting independently of one another.

Hepatic phosphorylase and epinephrine hyperglycaemia

The activities of various hepatic enzymes of hexose metabolism were studied in normal rats. The activities and their standard errors, expressed in micromoles of substrate reacting per minute per gramme wet-weight of liver at 30°, were found to be: glucose-6-phosphatase, 6.5 ( ± 0.34); fructose-1:6-diphosphatase, 5.0 ( ± 0.29); glucose-6-phosphate dehydrogenase, 1.1 ( ± 0.14); 6-phosphogluconic dehydrogenase, 2.6 ( ± 0.44); fructokinase, 4.5 ( ± 0.62); phosphorylase (towards glycogen), 12.3; phosphorylase (towards glucose-1-phosphate), 4.4. The high relative activity of phosphorylase, as well as its reversibility, raised serious questions as to the role of phosphorylase activation in epinephrine-induced hyperglycaemia. Furthermore, no alteration in the activity of this enzyme was detected when hyperglycaemia was prevented by administration of dihydroergotamine, or was produced by injection of epinephrine. These findings suggested that epinephrine administration must bring about, in addition to phosphorylase activation, events which alter the equilibrium conditions to those greatly favouring glucose formation or which activate an alternative pathway for glycogen breakdown.

Studies on the placental transfer of phosphate in the guinea pig. III. Phosphorus compounds in the placenta and their uptake of radioactive phosphorus.

Summary.Determinations of the various phosphorus fractious in the guinea pig placenta in a series of experiments on the placental transfer of phosphate have shown that the orthophosphate concentration is very high in the placental tissue as compared with the maternal and foetal plasma. The concentration increases slowly from the 29th to the 59th day of gestation and may decrease thereafter.Thirty minutes after intravenous injection of radioactive phosphate into the mother the orthophosphate in the placenta has reached a specific activity of one third of that of the inorganic phosphate in the maternal plasma. It has the highest specific activity of the placental phosphorus fractions.Adenosine diphosphate and triphosphate are found in approximately the same concentrations as in the uterine muscle during pregnancy in the rat, the rabbit and the human. The labile phosphorus of these compounds is in equilibrium with the orthophosphate with regard to radioactive phosphorus.Glucose‐1‐phosphate is present in a low concentration, but it acquires a high relative specific activity. More glucose‐6‐phosphate is present, but with a low relative specific activity.The inorganic phosphate in the foetal plasma obtains in thirty minutes a specific activity of about half that of the placental orthophosphate.