Concentrations Of Dinitrophenol Research Articles

Photobioelectrocatalysis of Intact Photosynthetic Bacteria Exposed to Dinitrophenol

AbstractInvited for this issue's Front Cover is the international collaborative team with researchers from Università degli Studi di Bari “Aldo Moro” (Italy), São Paulo State University (UNESP, Brasil), and Consiglio Nazionale delle Ricerche (Italy). The cover picture shows purple bacterial cells that hit, or miss, their “target electrode” with photo‐induced electrons depending on the concentration of dinitrophenol at which they are exposed. Under low dinitrophenol concentration, the electrons can reach the target, while under high dinitrophenol concentrations the electrons are diverted away from the electrode. Read the full text of the Research Article at 10.1002/celc.202300013.

Influence of UV radiation on the catalytic activity of nanosized cobalt ferrite in the oxidative degradation reaction of dinitrophenol

Due to their multi-functionality, spinel ferrites, both doped and undoped, are promising materials for a wide range of practical applications, including catalysis, sustainable production of hydrogen and СО2 deposition, electronic and magnet devices, as well as antibacterial agents. Recently, nanosized ferrites have been actively tested as catalysts in Fenton-like processes of deep oxidative degradation of organic substances in order to purify waste waters of different dyes, phenol and its derivatives, and antibiotics. The goal of this work was to establish the catalytic activity of СоFe2O4 nanopowder synthesisedusing citrate combustion in the reaction of oxidative degradation of 2,4-dinitrophenol upon the activation of the process with UV radiation. Using citrate combustion, we synthesised the impurity-free nanopowder of CoFe2O4 cobalt ferrite with the average size of particles of about 70 nm and a pronounced agglomeration of particles. The cobalt spinel was tested as a catalyst of Fentonlike reaction of oxidative degradation of 2,4- dinitrophenol with UV radiation of l = 270 nm. This process was differentiated with the sorption of dinitrophenol on a nanosized catalyst. The degree of degradation of 2,4-dinitrophenol in a Fenton-like reaction without the CoFe2O4 catalyst was 14 %, while in the presence of a nanosized catalyst it increased up to 80 %. The effective oxidative degradation of the pollutant was performed in a less acidic environment as compared to a classic Fenton process with a rather large initial concentration of dinitrophenol. This allowed considering the nanosized CoFe2O4 as a promising catalyst of Fenton-like of waste waters purification through deep oxidative degradation of toxins.

Photobioelectrocatalysis of Intact Photosynthetic Bacteria Exposed to Dinitrophenol

AbstractThe outstanding metabolic versatility of purple non‐sulphur bacteria makes these organisms an ideal candidate for developing photobioelectrochemical systems applicable in contaminated environments. Here, the effects of 2,4 dinitrophenol, a common contaminant, on purple bacteria photobioelectrocatalysis were investigated. The aromatic contaminant clearly affects current generation, with an enhanced photocurrent obtained at low dinitrophenol concentrations (0.5–1 μM), while higher values (up to 100 μM) resulted in a gradual decrease of photocurrent. The obtained electrochemical evidence, coupled to spectroscopic studies, allowed verifying the viability of the bacteria cells after exposure to dinitrophenol, and that no alteration of the photosynthetic apparatus was obtained. The results indicate that high dinitrophenol concentrations divert electrons from the extracellular electron pathway to an alternative electron sink. The present results open the door to the possible use of intact bacteria‐based photoelectrodes to develop technologies for sustainable biosensors with simultaneous environmental remediation.

Metformin Increases Mitochondrial Energy Formation in L6 Muscle Cell Cultures

A popular hypothesis for the action of metformin, the widely used anti-diabetes drug, is the inhibition of mitochondrial respiration, specifically at complex I. This is consistent with metformin stimulation of glucose uptake by muscle and inhibition of gluconeogenesis by liver. Yet, mitochondrial inhibition is inconsistent with metformin stimulation of fatty acid oxidation in both tissues. In this study, we measured mitochondrial energy production in intact cells adapting an in vivo technique of phosphocreatine (PCr) formation following energy interruption ("PCr recovery") to cell cultures. Metformin increased PCr recovery from either dinitrophenol (DNP) or azide in L6 cells. We found that metformin alone had no effect on cell viability as measured by total ATP concentration, trypan blue exclusion, or 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction. However, treatments with low concentrations of DNP or azide reversibly decreased ATP concentration. Metformin increased 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction during recovery from either agent. Viability measured by trypan blue exclusion indicated that cells were intact under these conditions. We also found that metformin increased free AMP and, to a smaller extent, free ADP concentrations in cells, an action that was duplicated by a structurally unrelated AMP deaminase inhibitor. We conclude that, in intact cells, metformin can lead to a stimulation of energy formation, rather than an inhibition.

Oxidative effect ferumoxytol and iron dextran on urinary bladder contraction and impact of antioxidants

IntroductionIntravenous (IV) iron compounds enjoy widespread clinical use. No studies have examined the effect of antioxidants on oxidative damage-associated changes in bladder contractility from IV iron compounds. ObjectiveTo determine if oxidative stress from 2 IV iron compounds effect rat bladder contraction and if coadministered antioxidants are protective. MethodsThree groups of 6 SD rats were studied. Group 1 received weekly 1 mg/kg doses of ferumoxytol (FX) or iron dextran (ID) for 5 doses. Group 2 received coenzyme Q10 (5 mg/kg) plus alpha lipoic acid (10 mg/kg) daily for 4 weeks before starting IV iron, then 1 mg/kg of the 2 iron compounds weekly for 5 doses. Antioxidant treatment continued until the last iron dose. Group 3 were controls and received saline and half received the antioxidants over the same time period. Seven days after the last iron dose, liver and heart samples were analyzed for nitrotyrosine (NT) and dinitrophenol (DNP) content. The contractile responses of bladder strips to field stimulation (FS) (2, 8, and 32 Hz), carbachol (10 μg), and KCl (120 mM) were determined. ResultsDNP concentrations in heart and liver after treatment with FX were similar to control. NT concentrations in both tissues were increased above control with FX. DNP and NT concentrations of both tissues due to ID were higher than both controls and FX. FX had no effect on bladder contractile responses to any form of stimulation, but ID produced decreases in bladder responses to all stimuli. Antioxidants had no effect on bladder contractility in FX-treated rats, but contractile responses to all forms of stimulation were increased by the antioxidants in ID-treated rats. The antioxidants had no effect on control rats. ConclusionFX and ID caused oxidative stress to several organs, but FX was less stressful than ID. Antioxidants attenuated the effects of ID on bladder contractility.

활성슬러지를 이용한 질소방향족화합물의 생물학적 분해 특성

Biological degradation of nitrogen-containing aromatic compounds was investigated in activated sludge previously adapted to mineralize low concentrations of nitrogen-containing aromatic compounds. Normally, the time required for 95% degradation of 10 mg/l dinitrophenol (DNP) under aerobic conditions was less than 4 hours without any lag, and with mixed liquor suspended solid (MLSS) levels from 600 to 1,000 mg/l. However, when the initial DNP concentration was increased to 75 mg/l, lags and even complete inhibition of DNP degradation were observed. The length of the lag was found to increase proportionally with decreasing MLSS levels. When dilute activated sludge was incubated for extended periods (192 hours), degradation of 75 mg/l DNP did eventually occur after lag periods of 37 to 144 hours, depending on the MLSS concentration. DNP was degradable in high concentrations if MLSS concentrations were sufficiently high to allow growth of bacteria resistant to the toxic effects of DNP.

Dinitrophenol-induced mitochondrial uncoupling in vivo triggers respiratory adaptation in HepG2 cells

Here, we show that 3 days of mitochondrial uncoupling, induced by low concentrations of dinitrophenol (10 and 50 μM) in cultured human HepG2 cells, triggers cellular metabolic adaptation towards oxidative metabolism. Chronic respiratory uncoupling of HepG2 cells induced an increase in cellular oxygen consumption, oxidative capacity and cytochrome c oxidase activity. This was associated with an upregulation of COXIV and ANT3 gene expression, two nuclear genes that encode mitochondrial proteins involved in oxidative phosphorylation. Glucose consumption, lactate and pyruvate production and growth rate were unaffected, indicating that metabolic adaptation of HepG2 cells undergoing chronic respiratory uncoupling allows continuous and efficient mitochondrial ATP production without the need to increase glycolytic activity. In contrast, 3 days of dinitrophenol treatment did not change the oxidative capacity of human 143B.TK − cells, but it increased glucose consumption, lactate and pyruvate production. Despite a large increase in glycolytic metabolism, the growth rate of 143B.TK − cells was significantly reduced by dinitrophenol-induced mitochondrial uncoupling. We propose that chronic respiratory uncoupling may constitute an internal bioenergetic signal, which would initiate a coordinated increase in nuclear respiratory gene expression, which ultimately drives mitochondrial metabolic adaptation within cells.

Selective spectrophotometric determination of trinitrotoluene, trinitrophenol, dinitrophenol and mononitrophenol

Contaminated land and groundwater remediation in military waste dumping sites often necessitates the use of simple, cost-effective and rapid tests for detecting trinitrotoluene (TNT) and trinitrophenol (picric acid; PA) residues in the field along with their dinitro-analogues. Using PA as the model compound, a simple and field-adaptable (on-site) colorimetric method was developed for quantifying PA in the presence of dinitrophenol (DNP) and mononitrophenol (NP). Most commercialized methods for TNT assay—with the exception of CRREL method—use proprietary chemicals, and the color stability and intensity are highly dependent on the composition of the organic solution comprised of acetone or methanol. The developed colorimetric method here is based on the extraction of the Meisenheimer anion formed from the reaction of PA and aqueous NaOH into isobutyl methyl ketone (IBMK) with a cationic surfactant such as cetylpyridinium bromide (CPB). The orange-red color that developed in the organic phase was persistent for at least 30min. TNT formed a similar extractable red complex under these conditions. If present, 2,4-dinitrophenol (DNP) and 4-nitrophenol (NP) could be detected by the same method at 17- and 167-fold concentrations of the LOD of PA, i.e. 1.5ppm. DNP alone could be quantified by another charge-transfer (CT) agent, imidazole, as a yellow product at 400nm in 98% EtOH solution. Under the same conditions, the intramolecular CT-band due to PA was essentially not intensified upon addition of the imidazole ligand, enabling the estimation of the DNP concentration from absorbance difference of solutions with and without imidazole, due to the intermolecular CT absorption of the latter. NP alone could be detected with a diphenylamine solution in H2SO4 to produce a blue color.

Rhodococcus erythropolis as the receptor of cell-based sensor for 2,4-dinitrophenol detection: effect of ‘co-oxidation’

Whole cells of Rhodococcus erythropolis were employed as a receptor of a microbial sensor for 2,4-DNP determination using an oxygen Clark-type electrode as a transducer. A linear relationship of the sensor response (the respiratory rate of R. erythropolis as receptor) to 2,4-DNP concentrations was obtained for concentrations in the range from 2×10 −5 to 20×10 −5 M. Dinitrophenol concentrations of above 10 −3 M inhibited R. erythropolis respiration. The sensor response to 2,4-DNP was shown to add up from two components: (1) the effect of 2,4-DNP as the respiratory substrate on the cells' respiration of receptor element; and (2) the stimulative effect of 2,4-DNP as protonophore on the cells' respiration. Dinitrophenol detection at concentrations of below 2×10 −5 M can be realized using the influence of 2,4-DNP upon the cells respiration in the presence of ethanol as an additional exogenous substrate (‘co-oxidation effect’). The mechanism of the ‘co-oxidation effect’ is discussed. A relationship between the activity of R. erythropolis respiration on ethanol and the activity of respiration on 2,4-DNP was found to exist. The level of this activity is supposed to depend on the content of nicotinamide nucleotides in the cells and oxidation-reduction state of these nucleotides.

Characterization of a Polyclonal Antihapten Antibody by Affinity Capillary Electrophoresis

We used affinity capillary electrophoresis (ACE) to characterize a heterogeneous population of polyclonal antibody (pAb) specific to a hapten, dinitrophenol (DNP). The binding migrationshift behavior of anti-DNP pAb to DNP in electrophoretic solution was observed and the affinities of subpopulations were studied. At large DNP excess, the pAb gradually split in two peaks and finally separated at saturating DNP-concentrations. The minor peak migrates at constant time and the major peak shifts away from the other with the increasing amount of DNP. This major peak represents a subpopulation of low to moderate affinity and very few or no high affinity antibodies exist in the major subpopulation. This observation was further verified by preincubation of pAb with saturating concentrations of DNP followed by CE analysis. It was found that the minor peak in fact represents a subpopulation of low affinity antibodies present in the preparation. The applicability of ACE as a useful tool for the analysis of polyclonal antibody population is demonstrated.

The influence of energy deficiency‐imposing conditions on the capacities ofAcetobacter methanolicus to oxidize glucose and to produce gluconic acid

AbstractThe presence of dinitrophenol (DNP) during the chemostatic growth of Acetobacter methanolicuson glucose led to i) no significant increase in glucose dehydrogenase, ii) a decrease in the capacity to oxidize glucose by about 30%, not depending on the DNP concentration, and iii) a gradual decrease in the capacity to form gluconic acid, depending on the concentration of the uncoupler. Similar effects of DNP on Acetobacter methanolicuswere observed during the gluconic acid formation process. The loss in the capacity to form gluconic acid is indicated by a drop in the ATP concentration of the cells which cannot be counteracted by the ATP syntheses originating from the oxidation of gluconic acid and of glucose. ATP could be necessary for pumping protons out of the cells that were taken up together with gluconic acid and by the effect of DNP.

Dinitrophenol influences the rate and yield of Acetobacter methanolicus during the growth on glucose

AbstractAcetobacter methanolicuswas grown on glucose in the presence of dinitrophenol (DNP) under carbon/energy‐limited conditions. DNP affected both the growth yield and the growth rate (Dsh) at which the energy generation was shifted from a complete to an incomplete substrate oxidation by using the PQQ‐linked glucose dehydrogenase. The more the growth yield was decreased, the higher both the DNP concentration and the growth rate became. At about 0.53 mM DNP, growth was completely stopped. Dsh decreased from 0.21h−1in the absence of DNP to 0.175 h−1and 0.075 h−1in the presence of 0.2 mM and 0.4 mM DNP, respectively. The experimental data are discussed in terms of the limitations in the generation of energy and some stress situations which are exerted by the presence of the uncoupler.

Mitochondrial adenosine triphosphatase ofPenetrocephalus ganapatii (Cestoda: Pseudophyllidea) in relation to activators and inhibitors

The mitochondrial adenosine triphosphatase of the cestode parasite,Penetrocephalus ganapatii exists as a latent form and is activated by dinitrophenol or MgCl2. Irrespective of MgCl2 or dinitrophenol concentrations, the enzyme shows optimum activity at pH 8. Effects of inhibitors on Mg2+, dinitrophenol and Mg2++dinitrophenol activated ATPase reveal that ATPase is not highly sensitive towards oligomycin and the alteration of the redox state of the respiratory chain components by rotenone, antimycin A, azide and cyanide has little effect on ATPase activity. −SH groups of the enzyme seem to play a limited role in the hydrolysis of ATP, as the enzyme is only partially sensitive top-chloromercuribenzoic acid. Generally, cations inhibit Mg2+ stimulated ATPase and activate dinitrophenol stimulated ATPase but most of the anions are inhibitory to dinitrophenol or Mg2+ stimulated ATPase.

Quinacrine-induced changes in mitotic PtK1 spindle microtubule organization.

Quinacrine, an acridine derivative which competitively binds to ATP binding sites, has been used to study the role of ATP requiring molecules in microtubule organization in mitotic PtK1 cells. Brief treatments of metaphase cells with concentrations of quinacrine ranging from 2 to 10 microM decreased spindle length and birefringence in a concentration-dependent manner. With either increasing quinacrine concentrations or duration of treatment, metaphase cells demonstrated a specific reorganization of spindle microtubules. Both polarization and electron microscopy showed a substantial loss of non-kinetochore spindle microtubules with an increase in astral microtubules: this was particularly evident in the region adjacent to the spindle domain. Addition of millimolar concentrations of dinitrophenol to quinacrine-containing medium did not potentiate the response of metaphase cells to quinacrine treatment. Time-lapse video analysis demonstrated that the astral microtubules are the result of reorganization of spindle microtubules. These data suggest that functional ATP binding sites are required to maintain stable interactions between microtubules and that these interactions are responsible for maintaining the bowed configuration of non-kinetochore spindle microtubules which are under compression at metaphase.

The ATP dependence of the degradation of short- and long-lived proteins in growing fibroblasts.

To characterize the system(s) responsible for degradation of short-lived and long-lived proteins in mammalian cells, we compared the concentrations of ATP required for the degradation of these classes of proteins in growing hamster fibroblasts. By treating CHEF-18 cells with increasing concentrations of dinitrophenol and 2-deoxyglucose, it was possible to reduce their steady-state ATP content by different amounts (up to 98%). These treatments caused a rapid decrease in the degradation of both short- and long-lived proteins. Removal of the inhibitors led to a prompt restoration of ATP and proteolysis. As ATP content fell below normal levels (about 3.1 mM), rates of proteolysis decreased in a graded biphasic fashion. Reduction in ATP by up to 90% (as may occur in anoxia or injury) decreased proteolysis up to 50%; and with further loss of ATP, protein breakdown fell more sharply. Degradation of both classes of proteins was inhibited by 80% when ATP levels were reduced by 98%. The levels of ATP required for the breakdown of short- and long-lived proteins were indistinguishable. Protein synthesis was much more sensitive to a decrease in ATP content than protein breakdown and fell by 50% when ATP was reduced by only 15%. Chloroquine, an inhibitor of lysosome function, did not reduce the degradation of either class of proteins in growing cells, but it did inhibit the enhanced degradation of long-lived proteins upon removal of serum (in accord with previous studies). Thus, in growing fibroblasts, an ATP-dependent nonlysosomal process appears responsible for the hydrolysis of both short- and long-lived proteins.

Different mechanisms underlying the stimulation of myocardial α- and β-adrenoceptors

On isolated electrically driven rat left atria (1 Hz) experiments were undertaken in order to characterize further the mechanism of the positive inotropic effect underlying the stimulation of cardiac α-adrenoceptors.— The increase in extracellular Ca 2+ from 1.25 to 2.5 mM increased the pD 2-value for the α-mimetic effect of phenylephrine by 0.6 log units. Under the same conditions the pD 2-value for its β-mimetic positive inotropic effect increased by only 0.19 log units.—When the amplitude of contraction was diminished by carbachol which is known to inhibit the influx of Ca 2+ the pD 2-value for the α-mimetic effect of phenylephrine was significantly increased while that for the β-mimetic effect was decreased.—After increasing concentrations of dinitrophenol the pD 2-value for the α-effect of phenylephrine was significantly increased by maximal 0.6 log units whereas that for the β-effect was lowered by 0.25 log units.—In conclusion, all measures favouring the conditions for an enhanced influx of Ca 2+-elevation of the gradient for Ca 2+, shortening of the plateau phase of action potential by carbachol, increased efflux of Ca 2+ by dinitrophenol- are able to increase the pD 2-value, i.e. the affinity of phenylephrine to cardiac α-adrenoceptors, thus demonstrating the importance of an increased Ca 2+-influx induced by stimulation of α-adrenoceptors.

Uncoupler-induced changes in mitochondrial structure detected by small-angle X-ray scattering

Small-angle X-ray scattering data suggest that major but reversible rearrangements of mitochondrial inner membrane structure are induced by uncouplers. Low levels of 2,4-dinitrophenol (10 μM) cause a perceptible wide-angle shift of the 20 mrad X-ray scattering maximum characteristic of intact liver mitochondria. Higher dinitrophenol concentrations (> 25 μM) reduce this scattering maximum to one-third its initial intensity. In terms of mitochondrial function, the former scattering change appears to correlate with the uncoupling of oxidative phosphorylation while the latter occurs in the course of dinitrophenol stimulation of mitochondrial ATPase activity.

Mechanism of Sulfate Transport Inhibition by Cycloheximide in Plant Tissues

Inhibition by cycloheximide of sulfate transport in both barley roots (Hordeum vulgare L.) and potato tuber (Solanum tuberosum L.) increases with increasing inhibitor concentration only to a limited extent, depending on the length of the tissue incubation with the inhibitor. In contrast to this, increasing concentrations of dinitrophenol have a rapid and total inhibitory effect on the active transport. Leucine transport in the same tissues is strongly inhibited by dinitrophenol but is not affected by cycloheximide, whereas incorporation into protein is mainly inhibited by cycloheximide. It appears that the mechanism of transport inhibition by cycloheximide in plant tissues consists in stopping new carrier synthesis and not in the disruption of energy flow. Sulfate carriers show comparable decay rates in barley roots and potato tuber, the mean life being shorter than that of the leucine carriers. These appear more stable in roots than in storage tissues.

Energy dissipation by calcium recycling and the efficiency of calcium transport in rat-liver mitochondria.

The recycling of endogenous calcium across the inner membrane of incubated mitochondria consists of a passive efflux of calcium from the matrix which is compensated by an active re-uptake of this ion from the medium. Upon addition of ruthenium red which inhibits only the re-uptake, mitochondrial calcium accumulated in the medium at a rate of 3.5 nmol × min−1× mg protein−1. The ATP balance of this experiment, measured with the help of [2-14C]pyruvate as a substrate, revealed that ruthenium red inhibited about 20% of the energy dissipation of the mitochondria. It is concluded that the calcium recycling is one of the processes related to state 4 respiration of the mitochondria. Ca/O ratios for the calcium recycling were calculated from the rates of calcium release into the medium and the concomitant decrease in the respiratory rates observed after addition of ruthenium red. When the calcium transport system was progressively inhibited with increasing concentrations of ruthenium red, the intramitochondrial ATP/ADP ratios and the rates of calcium release gradually increased up to a maximal value, whereas the Ca/O ratios concomitantly decreased. Moreover, in the presence of barely uncoupling concentrations of dinitrophenol the Ca/O ratios were larger than in the control, whereas in the presence of oligomycin they were smaller. These results indicate that the efficiency of mitochondrial calcium transport decreases when the mitochondria approach a state of a maximal energy charge.

Metabolic effects of hypoglycemic sulfonylureas—V: In vitro effects of sulfonylureas on mitochondrial adenosine triphosphatase activity

The ATPase (ATP phosphohydrolase, EC 3.6.1.4) stimulating activity of sulfonylureas has been examined. Sulfonylureas stimulate ATPase to variable extents, and this stimulation is oligomycin-sensitive. They are less active than 2,4-dinitrophenol and their relative stimulating activity parallels their uncoupling potency on oxidative phosphorylation. Carbutamide, which in itself does not stimulate ATPase, inhibits ATPase stimulation by other sulfonylureas. Experiments with combinations of chlorpropamide and P594, two active compounds, suggest that P594 penetrates more readily into mitochondria and is a stronger uncoupling agent. All sulfonylureas inhibit ATPase stimulated by optimal concentrations of dinitrophenol. Possible implications of these observations with regard to the metabolic effects of sulfonylureas are discussed.