Influence of environmental conditions on the amount of N2O released from activated sludge in a domestic waste water treatment plant

Waste water purification is characterized by intensive mineralization and nitrification processes. Because of the high O₂ demand, temporarily anaerobic conditions may be produced, and denitrification by nitrifying organisms as well as heterotropic denitrification may contribute to N₂O release. In situ measurements (1993–1994) suggest that N₂O is released from activated sludge in a domestic waste water treatment plant at an average rate of 1040 g m^–2h^–1 with a range between zero and 6198 g m^–2h^–1. The production of N₂O seems to be related to the concentration of NO ₂ ^– and NO ₃ ^– as well as to the pH. In the waste water about 75–200 g N₂O l^–1 is dissolved. This N₂O is released after discharge into the receiving waters. The N₂O is produced essentially by nitrification rather than by heterotropic denitrification. On a long-term scale the increasing use of mechanical-biological waste water purification plants world-wide may add increasingly to the anthropogenic production of N₂O, although the present amount of N₂O produced is negligible compared to its global terrestrial production.     

Interaction du 2,4-dichlorophénol et de l'eau oxygénée dans la destruction enzymatique de l'acideβ-indolylacétique

Summary DCP increases IAA destruction by bothLens andPhaseolus root breis. H₂O₂ inhibits catabolism byLens extracts but activates it whenPhaseolus is used, mainly when roots are cultivated in the dark and contain inhibitors of IAA destruction. DCP 1·10^–3 M and H₂O₂ 1·10^–4 or 1·10^–3 volume forLens and DCP 1·10^–4 M and H₂O₂ 1·10^–3 volume forPhaseolus nullify auxin catabolism.     

Respiratory burst in peritoneal exudate cells in response to a modified tuftsin

Intraperitoneal administration of tuftsin-M [Thr–Lys–Pro–Arg–NH–(CH₂)₂–NH–CO–C₁₅H₃₁] to Balb/C mice has been shown to induce a respiratory burst in the peritoneal exudate cells. The macrophages exhibited enhanced levels of O₂ ^–, H₂O₂, NADPH oxidase and myeloperoxidase, but the activities of superoxide dismutase, catalase and glutathione peroxidase remained virtually unchanged. The magnitude of the oxidative burst depended directly on the dose of tuftsin-M; higher activity was observed at higher doses of the peptide. Tuftsin-M enhanced the generation of both O ₂ ^– and H₂O₂ under in vitro conditions, as did phorbol myristate acetate. These results suggest that tuftsin-M could enhance non-specific defence against infections by activating the macrophages.     

Aufhebung der Thermothyrin-A-Sekretion der Schilddrüse durch Fütterung mit Methylthiouracil

Summary G. Mansfeld demonstrated that in the serum of overheated animals a substance (thermothyrine A) is present which, injected into normal animals, decreases O₂-consumption. Serum of thyroidectomized animals has no effect.Dogs and rabbits were treated daily with 0.10 g per kg methylthiouracil during 4 weeks, and were than subjected for 5 hours to a temperature of 34–35° C which raised their body temperature by 0.5–1.5° C. 2.5 cm³ of serum obtained at the end of the 5 hours period failed to reduce O₂-consumption of normal rats, while sera of untreated dogs and rabbits produced after similar exposure to high temperature a fall of O₂-consumption by 14–48%. It is therefore evident that methylthiouracil not only inhibits the formation of thyroxine but of thermothyrine A as well.The fact that thermothyrine A contains no iodine proves conclusively that the action of thiouracil compounds cannot be exclusively an inhibition of iodinization.     

Experimental data on the energetic flux during glycolytic oscillations in yeast extracts

Calorimetric experiments were performed on yeast extracts in which glycolytic oscillations were occurring. High metabolic fluxes coincided with low amplitudes and with high frequencies in a temperature range from 283 to 303 K, yielding an activation energy ofE _a=76.8 kJ mol^–1 and a mean Q₁₀ value of 2.5±0.4. The calorimetrically determined reaction enthalpy _fH^0, of the glycolytic catabolism of glucose revealed two distinct groups of extract preparations, with no intermediate values. The values were –107.5±28.7 kJ mol^–1 and –30.8±5.7 kJmol^–1, respectively, while –100.0 kJ mol^–1 was predicted from theoretical calculations. Kreuzberg and Betz⁶ predicted rate limiting effects of GAPDH in oscillating extracts. However, when possible effects of GAPDH on frequency, number of oscillations or total heat production were examined, no influence of increasing or reducing the initial GAPDH concentration could be found. The results are discussed with reference to existing models of glycolytic oscillations.     

Zum Reaktionsmechanismus von Oxydasen

Summary The reactivity of copper(I)-complexes towards molecular oxygen in relation to some copper containing enzymes has been studied. The oxydation of simple amine-complexes proceeds at a rate of about 10³–10⁴ Mol^–1 Lt Min^–1. Replacing the amine by amides and peptides has a strong retarding effect. A copper(I)-cysteine complex exhibits the interesting property of adding O₂ reversibly.     

Die katalytische Mutation der Ionen Al3+ und MoO

Summary The catalytic mutation of the ions Al³⁺ and MoO ₄ ^2– on the mixed carrier Cd(OH)₂/Co(OH)₂(Tr) is recognizable by the fact that the combination Tr+Al³⁺+MoO ₄ ^2– is more active in the decomposition of H₂O₂ than the combination Tr+MoO ₄ ^2– +Al³⁺.     

Studies on hydrogen,halides and thiocyanate ions in dioxane-water mixtures at various temperatures

Summary The free enrgies of transfer (G _t ⁰ ) of H⁺, Cl^–, Br^–, I^– and SCN^– ions from water to 10, 20, 30 and 40% dioxanewater mixtures have been studied from potentiometric measurements. For anions the G _t ⁰ values are in the order Cl^–>Br^–>SCN^–>I^–.     

The molecular composition of a photographic fixing bath

Zusammenfassung In Thiosulfatlösungen von mäßiger Stärke bildet Silber die zwei Ionen Ag(S₂O₃) ₂ ^3– und Ag(S₂O₃) ₃ ^5– , deren Komplexkonstanten bestimmt wurden.     

Involvement of reactive oxygen species in the microsomal S-oxidation of thiobenzamide

Summary Superoxide dismutase, catalase and methional proved capable of inhibiting the microsomal oxidation of thiobenzamide, which is most probably catalyzed by the flavin-containing monooxygenase. This indicates that excited oxygen species (e. g.·O ₂ ^– , H₂O₂, ·OH) are involved in the catalytic cycle of this enzymatic reaction. CO, which inhibits the cytochrome P-450-dependent oxygen radical formation, had no effect on the oxidation reaction, suggesting that the source of the reactive oxygen species is not the microsomal mixed-function oxidase.     

Biliverdin as an electron transfer catalyst for superoxide ion in aqueous medium

Summary Stopped flow experiments gave evidence of the formation of a biliverdin-superoxide complex and/or a biliverdin radical anion by reaction of aqueous O₂ ^– with biliverdin. Such transient species are likely intermediates both in the bleaching of biliverdin, during exposure to the aerobic xanthine oxidase reaction, and in the reduction of ferricytochromec under the same conditions.     

Regulation ofL-valine absorption by opioids interacting withμ-receptors in rabbit ileum

In intact tissue, [d-Ala²,MePhe⁴, Gly-ol⁵] enkephalin (10^–5 M;-ligand), diminsihed short-circuit current (I_sc) and increased water, Na⁺ and Cl^– net fluxes in vitro under open circuit conditions; it also inhibitedL-valine absorption andL-valine-dependent variations of short-circuit current (I_{sc, val}). Naloxone (10^–6 M) antagonized these effects. In the absence of the muscularis and myenteric plexus this enkephalin or morphine (-ligand) reduced I_sc and I_{sc, val}. These enkephalin effects occurred at different times. Different concentrations of enkephalin were tested for their effects on I_{sc, val}. [d-Ala²,d-Leu⁵] enkephalin (mainly a -ligand) significantly decreased I_sc but not I_{sc, val}. The reduction ofL-valine absorption does not depend on the effects on basal ion transport. Interaction of opioids with-receptors located in the submucosal plexus and/or in the epithelial cell accounts for this reduction. This enkephalin effect seems to be at least partially under the control of the myenteric plexus.     

Induction of the in vitro p-hydroxylation of14C-amphetamine stereoisomers in phenobarbital-treated rats

Summary The rate of p-hydroxylation of¹⁴C-(-)-amphetamine by liver microsomes was higher than that of (+)-isomer in phenobarbital-treated male rats. The apparent K_m values for (-)- and (+)-amphetamine hydroxylation were 4.54×10^–5 M and 2.27×10^–5 M respectively, in both treated and control animals.     

Effects of selective dopamine D1 and D2 antagonists on male rat sexual behavior

Summary The effects of selective dopamine (DA) D₁ and D₂ antagonists on male rat sexual behavior were investigated. The D₁ antagonist (+)SCH-23390, 25–100 g kg^–1 s.c. –20 min, and the D₂ antagonist raclopride, 0.1–1.6 mg kg^–1 s.c., –20 min, decreased both the number of mounts and intromissions preceding ejaculation. No statistically significant effects in the time up to ejaculation or in the time up to the first intromission were noted, whereas both compounds produced a statistically significant increase in the post-ejaculatory interval. The effect can generally be characterized as psychomotor inhibition, and no evidence was obtained for a specific role of DA D₁ or D₂ receptors in the mediation of male rat sexual behavior.The expert technical assistance of Ms Elisabeth Wallin is gratefully acknowledged. The figures were skilfully prepared by Ms Madelene Kröning at the Department of Psychology. This study received support from the Bank of Sweden tercentenary Foundation, The Swedish MRC and Wilhelm and Martina Lundgren Foundation.     

Cell-to-cell transmission in the activation of in situ nematocytes in acontia ofCalliactis parasitica

Summary It is reported that Ca²⁺-induced discharge of in situ nematocytes of acontia ofCalliactis parasitica can occur by cell-to-cell transmission along the acontial filament at a speed that averages 9.8·10^–3 cm^–1. The discharge is preceded by protrusion of nematocytes that proceeds along the acontium at a slightly higher speed.     

Oxidative stress in the moderately halophilic bacteriumDeleya halophila: Effect of NaCl concentration

The sensitivity ofDeleya halophila to oxidative stress caused by hydrogen peroxide (H₂O₂) was found to vary, depending on the NaCl concentration of the growth medium. Pretreatment of the bacteria at a low concentration of H₂O₂ (50 M) protected the cells against the lethal effects of higher levels (1–2 mM) of H₂O₂. Exposure ofD. halophila cells to 50 M H₂O₂ resulted in the induction of several proteins (hydrogen peroxide-inducible proteins, hips). However, the kinetics of induction, the extent of induction and the number of hips appear to be influenced by the salt concentration of the growth medium. Five of the hips exhibited apparent molecular masses identical to those of five heat shock proteins (hsps).     

Bactericidal activity againstPseudomonas aeruginosa is acquired by cultured human monocyte-derived macrophages after uptake of myeloperoxidase

Myeloperoxidase (MPO) is an enzyme located within polymorphonuclear neutrophils capable of producting cytotoxic oxidant species that are particularly active against bacteria with polysaccharide capsules.Pseudomonas aeruginosa (10⁶ bacteria per 1 ml) are killed within 1 h in vitro by a MPO/H₂O₂/Cl^– system (48 mU=132 ng of MPO). The question arose as to whether human macrophages would acquire cytotoxic activity when loaded with this enzyme. Monocytes were therefore isolated from human blood and cultured for up to ten days to induce maturation to macrophages. These cells lost endogenous MPO within five days while H₂O₂ production in response to stimulation by phorbol myristate acetate (10^–6M) decreased to 23% within ten days. On the other hand, their capacity to take up exogenous MPO increased fourfold from day three to day ten. Human macrophages cultured from eight days (when both H₂O₂ production and MPO uptake were sufficient) were therefore used to study the effects of MPO uptake on cytocidal activity againstPseudomonas aeruginosa. After a 1 h MPO loading period, macrophages (5×10⁵ cells per ml) were incubated in the presence of bacteria (0.5 to 2×10⁶ bacteria per ml) for 2 h at 37°C. At a bacteria/macrophage ratio of 1, only 34.8±7.0% of bacteria survived (compared to killing by non-loaded macrophages), while 74.4±9.3% survived at a ratio of 4. From these results, we conclude that loading macrophages with exogenous MPO could enhance their microbicidal activity, suggesting a potentially useful therapeutic application.     

Soybean photosynthesis: simultaneous14CO2 and O2 estimates

Summary A method of estimating the photosynthetic rate of soybean leaves using an oxygen electrode is presented. The procedure is rapid, requires small samples and compares favourably with estimates by other techniques. Light saturation occurs at 1200 E·m^–2·sec^–1. The apparent K_m for HCO ₃ ^– is 3.2 mM at pH 7.6.     

Zur Stereochemie der Propandioldehydrase-Reaktion

Summary Propanedioldehydrase is shown to convert both (+)-(S)-2-²H-propanediol,3, and (–)-(R)-1-²H₂-propanediol,5, to specimens of deuterated propion-aldehyde, for which the (S)-configuration has been established. Thus, in the propanedioldehydrase reaction migration of hydrogen atoms from C–1 to C–2 always occurs with inversion of configuration.     

A potent attractant of zoospores ofAphanomyces cochlioides isolated from its host,Spinacia oleracea

A highly potent attractant of zoospores ofAphanomyces cochlioides, a causal fungus of the root rot disease of spinach (Spinacia oleracea), was isolated from spinach roots, and its structure was determined by spectroscopic evidence and chemical synthesis as cochliophilin A (5-hydroxy-6,7-methylenedioxyflavone,1). A chromosorb particle prepared by soaking in solution of1 showed a potent attracting activity toward the zoospores using concentrations of1 above 10^–9 or 10^–10 M.