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PubMed1978

Ethylene formation by polymorphonuclear leukocytes. Role of myeloperoxidase.

Ethylene formation from the thioethers, beta-methylthiopropionaldehyde (methional) and 2-keto-4-thiomethylbutyric acid by phagocytosing polymorphonuclear leukocytes (PMNs) was found to be largely dependent on myeloperoxidase (MPO). Conversion was less than 10% of normal when MPO-deficient PMNs were employed; formation by normal PMNs was inhibited by the peroxidase inhibitors, azide, and cyanide, and a model system consisting of MPO, H2O2, chloride (or bromide) and EDTA was found which shared many of the properties of the predominant PMN system. MPO-independent mechanisms of ethylene formation were also identified. Ethylene formation from methional by phagocytosing eosinophils and by H2O2 in the presence or absence of catalase was stimulated by azide. The presence of MPO-independent, azide-stimulable systems in the PMN preparations was suggested by the azide stimulation of ethylene formation from methional when MPO-deficient leukocytes were employed. Ethylene formation by dye-sensitized photooxidation was also demonstrated and evidence obtained for the involvement of singlet oxygen (1O2). These findings are discussed in relation to the participation of H2O2, hydroxyl radicals, the superoxide anion and 1O2 in the formation of ethylene by PMNs and by the MPO model system.

Azides↗
PubMed2026

Ethylene signaling negatively regulates rapeseed resistance to Plasmodiophora brassicae.

Clubroot, caused by Plasmodiophora brassicae, poses a serious threat to the rapeseed (Brassica napus) industry. Due to B. napus being an allopolyploid with a complex genome and the current scarcity of available resistance gene resources, the molecular basis of rapeseed resistance to P. brassicae remains poorly understood. Here, we performed a functional characterization of BnEIN2 (ethylene-insensitive protein) to explore the role of ethylene signaling in rapeseed resistance to P. brassicae. The Bnein2 mutants generated through CRISPR/Cas9 technology exhibited enhanced resistance to P. brassicae, along with reduced 1-aminocyclopropane-1-carboxylic acid (ACC)/S-adenosyl-L-methionine (SAM) accumulation and ethylene insensitivity. Pharmacological assays demonstrated that inhibitors of ethylene biosynthesis or signaling improved the resistance of Bnein2 mutant plants to P. brassicae. Transcriptome analysis revealed that loss-of-function of BnEIN2 affected the expression of ethylene-, auxin-, and cytokinin-related genes. Moreover, the increased resistance of Bnein2 mutants to P. brassicae was accompanied by a reduction in auxin (indole-3-acetic acid, IAA) biosynthesis and degradation of cytokinin (trans-zeatin, TZ). Collectively, these findings establish the negative regulatory role of ethylene signaling in rapeseed resistance to P. brassicae. This study represents the first effort to elucidate rapeseed resistance to P. brassicae by directly obtaining rapeseed genetic material and offer novel insights into the hormonal regulatory network underlying disease resistance and valuable resources for breeding clubroot-resistant varieties.

BnEIN2↗
PubMed1975

Production of ethylene and other volatiles and changes in cellulase and laccase activities during the life cycle of the cultivated mushroom, Agaricus bisporus.

Nine volatile hydrocarbons, as well as methyl chloride, carbonyl sulphide and carbon disulphide, have been identified by mass spectrometry as products of Agaricus bisporus in the compost used in comerical mushroom beds. Of these, only ethylene showed a pattern of production that could be correlated with developmental phases of the crop, high levels being produced whenever fruit bodies were rapidly enlarging. In laboratory flask cultures, under controlled conditions, high levels of ethylene occurred whenever young fruit bodies entered the expansion phase. The enhanced rate of ethylene production continued over several days, irrespective of whether fruit bodies were removed. Production occurred within the colonized compost; no ethylene was evolved by the fruit body itself. When the first fruit bodies expanded, either in beds or culture flasks, laccase levels in the compost fell and those of a beta-1,4-glucanase (cellulase) rose. The enzyme switch occurred once only, during maturation of the first fruit bodies, whereas an elevated ethylene production was associated with each occasion when fruit body maturation took place. The low level of laccase and high of cellulase characterized the whole of the reproductive stage of A. bisporus, whereas the phasic periods of high ethylene production distinguished between periods of fruit body maturation and intervening resting periods.

Agaricales↗
PubMed1977

Evaluation of the role of methional, 2-keto-4-methylthiobutyric acid and peroxidase in ethylene formation by Escherichia coli.

During growth of Escherichia coli strain SPA O in the presence of methionine, an intermediate accumulates in the medium. This intermediate reacts with 2,4-dinitrophenylhydrazine, and can be degraded to ethylene either enzymically or photochemically, the latter being stimulated by the addition of a flavin. The pH optimum for the photochemical degradation of this intermediate and 2-keto-4-methylthiobutyric acid (KMBA) is pH 3 whereas the optimum for methional is pH 6. The enzyme which converts the intermediate to ethylene also converts KMBA to ethylene and has many of the properties of a peroxidase including inhibition by catalase, cyanide, azide and anaerobiosis. The enzyme which synthesizes the intermediate is not known but requires oxygen and pyridoxal phosphate. A pathway for ethylene biosynthesis is proposed in which methionine is converted to KMBA which can be degraded either by peroxidase or in a flavin-mediated photochemical reaction. Its relevance to the properties of other ethylene-producing bacteria and to the proposed pathway of ethylene release by higher plants is discussed.

Aerobiosis↗
PubMed1978

Effects of ethylene on the metabolism of Saccharomyces cerevisiae.

Supply of exogenous ethylene to lactate-grown yeast initially accelerated the rate of ethanol production from glucose, but later reduced the rate, with the overall effect being to reduce the total ethanol production. The rate of ethanol production by ethylene-treated yeast was not changed by removal of metabolic carbon dioxide. However, if CO2 was allowed to build up in the absence of applied ethylene, the ethanol production decreased. Ethylene increased the activities of a number of pentose phosphate and glycolytic pathway enzymes. The largest increase in activity was observed for phosphofructokinase (EC 2.7.1.11), regulatory enzyme of the glycolytic pathway. After an initial stimulation, glucose (and also 3-O-methyl glucose) uptake was reduced by ethylene. Ethylene appears to inhibit non-competitively the glucose transport system.

Alcohol Oxidoreductases↗
PubMed1979

In vitro evaluation of hemolytic and cell culture toxicity potential of residual ethylene oxide in selected medical materials.

The hemolytic potential of pure ethylene oxide in solution was evaluated as a function of initial ethylene oxide concentration in three test systems, diluted whole blood in isotonic saline, erythrocytes washed and resuspended in isotonic saline, and erythrocytes washed and resuspended in isotonic phosphate buffer. Concentrations of 2 mg/ml (2000 ppm) were necessary before cell lysis was observed in either of the isotonic saline systems. This value increased to 10 mg/ml 10,000 ppm) in the isotonic buffer system. Efforts have been made to correlate the hemolysis and cell culture toxicity of residual ethylene oxide in five medical materials to the toxicity of pure ethylene oxide. Only materials exhibiting a low order of inherent toxicity showed any correlation. In poly(vinyl chloride) tubing containing 1.8 and 2.1 mg ethylene oxide per gram of material, a small amount of toxicity was seen in the cell culture system but toxicity was absent in the hemolysis test.

Blood↗
PubMed1976

Oxidation of ethylene by soil bacteria.

The course of the biological oxidation of ethylene by soil was dependent on the type of soil used as well as on other factors. As evidenced from an increase in oxidation rate, the ethylene-consuming microorganisms in soil could grow at the expense of ethylene, even when the gas was present at concentrations of 50 ppm or less. Five strains of bacteria strongly resembling each other were isolated from different soils. These pleomorphic, gram-positive, acid-fast, obligate aerobic, ethylene-oxidizing bacteria grew also on saturated alkanes and on ordinary carbon sources. An apparent Km for ethylene of approximately 40 ppm was estimated for whole-cell suspensions of strain E20 by following the disappearance of the gas from the atmosphere.

Bacteria↗
PubMed1979

Analysis of ethylene oxide--worker exposure.

A personal air sampling method for assessing individual worker exposure to ethylene oxide has been developed. The method is based on trapping ethylene oxide in dilute sulfuric acid where it is converted to ethylene glycol. The ethylene glycol is determined by gas chromatography using a glass column packed with 5% Igepal CO-990 on Teflon T-6. This column produces linear calibration curves and symmetrical peaks. The method has been shown to recover 94.2% ethylene oxide in the 1 to 8 ppm concentration range. The sampling technique is independent of flow and sample size. Advantages over the NIOSH method are discussed.

Air Pollutants↗
PubMed1978

Oxygen activation in isolated chloroplasts. Mechanism of ferredoxin-dependent ethylene formation from methionine.

Low-potential electron acceptors of photosystem I of chloroplast lamellae produce superoxide anions (0-2) and hydrogen peroxide by autoxidation, but have no effect on ethylene formation from methionine; equimolar amounts of ferredoxin are less active in photosynthetic O-2 and H2O2 production but strongly stimulate ethylene production from methionine. 2. Ten to fifty units of superoxide dismutase inhibit fifty to two hundred units of superoxide dismutase stimulate ethylene formation from methionine by chloroplast lamellae in the presence of ferredoxin. This stimulation is stronger at pH 7.0 than at pH 7.8. Catalase inhibits ethylene formation from methionine. 3. Pulse-radiolytic production of nitrite (NO-2) from hydroxylamine, initiated by hydroxyl radicals (.OH) or O-2, shows no difference in the presence or absence of ferredoxin, nor do the decay kinetics of O2. 4. From the above observations and from model reactions (xanthine/xanthine oxidase; iron salts in the presence of H2O2), it is concluded that reduced ferredoxin in the presence of H2O2 forms a Fenton-type oxidizing species for methionine, generating ethylene in the presence of pyridoxal phosphate. 5. Inhibitory effects of both superoxide dismutase and catalase in oxygen-dependent reactions need not necessarily indicate the participation of the 'Haber-Weiss' reaction.

Chloroplasts↗
PubMed1979

An evaluation of ethylene glycol-based liquid specimens for use in quality control.

We investigated the analytical acceptability of ethylene glycol-based control sera by preparing sets of aqueous and ethylene glycol-based specimens that had added uric acid, calcium, creatinine, glucose, urea, sodium, and potassium. Ethylene glycol caused a significant systematic proportional bias in procedures involving dialysis, but had no discernible effect on methods not involving dialysis. The extent of bias was proportional to the concentration of ethylene glycol, was independent of protein concentration, and differed according to the type of dialysis system used. We conclude that ethylene glycol-based control materials can have useful applications in clinical chemistry, but caution must be exercised in their use with analytical systems that employ dialysis.

Autoanalysis↗
PubMed1979

Ethylene glycol toxicosis in cattle.

A 1-month-old Jersey calf died of oxalate nephropathy. The calf had access to antifreeze (ethylene glycol) 3 days prior to death. Since ethylene glycol toxicosis had not been reported in cattle, the effects or oral administration of ethylene glycol were studied in 7 calves and 3 cows. The toxic dose ranged from 2 to 10 ml of ethylene glycol per kg of body weight. Clinical signs were increased respiration, staggering gait, paraparesis, depression and later, recumbency and death. Hemoglobinuria and epistaxis were seen at doses of 10mg/kg of body weight. Azotemia, hypocalcemia and neutrophilia were constant findings whereas acidosis, plasma hyperosmolality and hemolytic anemia were seen in the animals receiving the higher doses. A diagnosis of ethylene glycol toxicosis must be based upon a history of ingestion and the presence of calcium oxalate crystals in body tissues (especially the kidney and brain).

Animals↗
PubMedDate not supplied

In vitro metabolism of 1,2-dihaloethanes to ethylene.

1,2-Dichloroethane (DCE), a solvent and byproduct of the manufacture of polymers, and 1,2-dibromoethane, a soil fumigant, are known to be metabolized by conjugation with glutathione (GSH) to yield mercapturic acid derivatives. An alternate route of metabolism of the GSH conjugate involves beta-elimination of halide ion to form an olefin. In the present study, ethylene production from DCE was measured by gas chromatography in rat tissues as an index of this latter route of metabolism. The rate of enzymic ethylene production was linear over a 1-hr incubation time and from 1 to 8 mg of protein per ml reaction volume. The temperature optimum for ethylene formation from DCE was 55 degrees C and no distinct pH optimum was observed. DCE metabolism was highly dependent on the presence of reduced GSH. Metabolic activity was limited to hepatic and renal cytosolic fractions. The reaction was inhibited only by p-chloromercuribenzoic acid and by diethyl maleate and methyl iodide, which are substrates for GSH S-transferases. (S-(-2-Chloroethyl)-DL-cysteine . HCl, an analog of the conjugate formed from DCE and GSH, was nonenzymically converted to ethylene.

Animals↗
PubMed1978

Electron-paramagnetic-resonance studies on nitrogenase of Klebsiella pneumoniae. Evidence for acetylene- and ethylene-nitrogenase transient complexes.

Klebsiella pneumoniae nitrogenase exhibited four new electron-paramagnetic-resonance signals during turnover at 10 degrees C, pH7.4, which were assigned to intermediates present in low concentrations in the steady state. 57Fe-substituted Mo--Fe protein showed that they arose from Fe--S clusters in the Mo--Fe protein of nitrogenase. The new signals are designated: Ic, g values at 4.67, 3.37 and approx. 2.0; VI, g values at 2.125, 2.000 and 2.000; VII, g values at 5.7 and 5.4; VIII, g values at 2.092, 1.974 and 1.933. The sharp axial signal VI arises from a Fe4S4 cluster at the --1 oxidation level. This signal was only detected in the presence of ethylene and provides the first evidence of an enzyme--product complex for nitrogenase. [13C]Acetylene and [13C]ethylene provided no evidence for direct binding of this substrate and product to the Fe--S clusters giving rise to these signals. The dependence of signal intensities on acetylene concentration indicated two types of binding site, with apparent dissociation constants K less than 16 micron and K approximately 13mM. A single binding site for ethylene (K=1.5mM) was detected. A scheme is proposed for the mechanism of reduction of acetylene to ethylene and inhibition of this reaction by CO.

Acetylene↗
PubMed1975

Biospecific affinity chromatography in aqueous-organic cosolvent mixtures. The effect of ethylene glycol on the binding of lactate dehydrogenase to an immobilised-AMP analogue.

The effect of the weak polarity-reducing agent, ethylene glycol, on the binding of pig heart lactate dehydrogenase to N6-(6-aminohexyl)-AMP-Sepharose has been investigated. In the absence of the reagent and under the conditions used, a non-specific interaction of the enzyme with the adsorbent led to recoveries of enzyme activity as low as 60% when the enzyme was eluted from the columns with a linear NADH gradient. The inclusion of low concentrations of ethylene glycol in column irrigants considerably improved the recovery of enzyme activity with quantitative recoveries being obtained in the presence of 20-30%. Concentrations of ethylene glycol about 35% altered the native conformation of lactate dehydrogenase and led to a decreased affinity for the immobilised ligand. Under these conditions, the altered protein fluorescence and decreased ability to bind NADH could be correlated with the chromatographic behaviour of the enzyme on columns of N6-(6-aminohexyl)-AMP-Sepharose. These effects were exploited to elute the enzyme from a column of immobilised-AMP with a linear gradient of ethylene glycol.

Adenosine Monophosphate↗
PubMed1977

Stimulatory and inhibitory effects of dimethyl sulfoxide and ethylene glycol on ATPase activity and calcium transport of sarcoplasmic membranes.

1. The effect of dimethyl sulfoxide (Me2SO) and ethylene glycol on two different preparations of the sarcoplasmic reticulum, i.e. native membranes and membranes whose phospholipids were hydrolyzed by phospholipase A, were investigated using ATP and p-nitrophenylphosphate as substrates. 2. Me2SO and ethylene glycol inhibit both calcium-dependent ATP hydrolysis and ATP-supported calcium transport by native vesicles. 3. In contrast, calcium-dependent p-nitrophenylphosphatase activity as well as p-nitrophenyl-phosphate-supported calcium transport are activated by both agents at concentrations lower than 30% (v/v). 4. Me2SO strongly stimulates p-nitrophenylphosphate activity of vesicles treated with phospholipase A, but has relatively little effect on p-nitrophenylphosphatase activity of native vesicles. 5. Up to a concentration of approximately 40% Me2SO (v/v) the inhibiting effect on the calcium-dependent ATPase is fully reversible, but only partially reversible on calcium transport. 6. In the concentration range where Me2SO inhibits ATP hydrolysis and calcium transport, it does not affect ATP binding to the membranes nor calcium-dependent formation of phospho-protein. 7. The rate of dephosphorylation as well as the rate of Pi exchange between ATP and ADP are markedly reduced by the presence of 30% Me2SO (v/v). 8. While Me2SO inhibits passive calcium efflux, ethylene glycol produces a considerable activation. 9. ADP-dependent calcium efflux and ATP synthesis are activated by 15% Me2SO (v/v). Ethylene glycol reduces both activities. 10. The results suggest that the respective substrate-enzyme complexes are differently affected by the agents, resulting either in inhibition or stimulation

4-Nitrophenylphosphatase↗
PubMed1979

Biological indicators for the control of ethylene oxide sterilization.

A new biological indicator has been developed for the control of ethylene oxide sterilization, particularly for large scale sterilization of disposable medical equipment. The aim has been to provide the new indicator with the same resistance to the combined effect of ethylene oxide and water vapour as the biological indicator referred to by the health authorities in Scandinavia. The reference indicator contains spores of a Danish test strain, Bacillus subtilis, in sand. The new one contains spores of a test strain used extensively for biological indicators, viz. B. subtilis var. niger (B. globigii). The spores in the new preparation are dried in pieces of cotton yarn. The two indicators were exposed to ethylene oxide and water vapour in five different series of experiments and almost the same resistance was found. In simulated routine sterilization procedures, the new indicator was placed at locations not easily accessible for the gas and water vapour, and the results reflected the blockage of diffusion. The experiments included samples of household dust. The resistance of the microorganisms in the dust was compared with that of the biological indicators. Based on these comparisons, it is concluded that the resistance of the two biological indicators to ethylene oxide is in accordance with the official Scandinavian standard for sterilized medical equipment when used in the control of sterilization of products with low microbial contamination.

Bacillus subtilis↗
PubMed1977

Ethylene production by soil microorganisms.

Ethylene-producing strains of Penicillium cyclopium and P. crustosum were isolated from soil. These isolates produced ethylene on a variety of carbon growth substrates including phenolic acids. The quantities of ethylene produced on the various substrates varied, and the subtrate-ethylene prosuction pattern for P. cyclopium strains differed significantly from that of P. crustosum strains.

Acetates↗
PubMed1979

Toxic effects of some alcohol and ethylene glycol derivatives on Cladosporium resinae.

Eleven commercially available alcohol and ethylene glycol derivatives were tested for their toxicity toward a problem organism in jet fuel, Cladosporium resinae. In the presence of glucose, 20% (vol/vol) ethylene glycol monomethyl ether prevented spore germination and mycelial growth, and 10% (vol/vol) 2-ethoxybutanol, 10% 2-isopropoxyethanol, 10% 3-methoxybutanol, 5% 2-butyloxyethanol, 5% ethylene glycol dibutyl ether, and 5% diethylene glycol monobutyl ether were found to have similar effects. In a biphasic kerosene-water system, 3-methoxybutanol, 2-butyloxyethanol, and diethylene glycol monobutyl ether were again found to be more toxic than ethylene glycol monomethyl ether. Considerable potassium efflux, protein leakage, and inhibition of endogenous respiration were observed in the presence of the more toxic compounds. 2-Butyloxyethanol also caused loss of sterols from cells.

Alkanes↗