Increase In Peroxide Concentration Research Articles

Bright and long-lasting aqueous peroxyoxalate chemiluminescence in cellulose microspheres.

Water decreases the brightness of the peroxyoxalate chemiluminescence partially due to the hydrolysis of the oxalate reagent. Here, we show that encapsulation of an oxalate ester and the fluorescent activator in microspheres of cellulose esters increases the emission intensity 30 times compared to the same reaction in water without encapsulation, whereas the emission intensity decay rate constants are considerably lower. Emission intensities, rate constants and chemiluminescence quantum yields increase with increasing hydrogen peroxide concentrations. These results expand the potential of application of chemiluminescence, contributing for the development of ultrasensitive analytical methods.

Wood-Based Biochar Ratio Used for Partial Peat Replacement in Growing Media for Antirrhinum majus Pot Production

Biochar has been promoted mostly as a soil supplement that improves plant growth/yield and to a lesser extent as a growing medium component. The alarmed situation for peat substitution in growing medium renders biochar as a promising substitute for current research. In this study, biochar derived by wood-based materials was evaluated at different ratios (0, 5, 10, 15, and 20% v/v) for peat partial substitution for Antirrhinum majus pot production. Biochar had increased potassium content and pH, which affected the growing media properties (total pores space and water filled capacity) and decreased nitrogen and phosphorus content in the media. Adding ≥15% biochar increased plant height and decreased flowering, but no effect was observed on plant biomass produced. The presence of biochar increased the total phenols and flavanols content and antioxidant capacity, with greater effects at the higher biochar rates used. This resulted in lipid peroxidation and an increase in hydrogen peroxide content, causing oxidative stress. Potassium and magnesium accumulated more but nitrogen and phosphorus were accumulated less in snapdragon leaves. Biochar at 10% can be considered as a successful candidate to partially substitute peat, and efforts to improve growing media characteristics are required for A. majus pot production.

High Levels of Erucic Acid Cause Lipid Deposition, Decreased Antioxidant and Immune Abilities via Inhibiting Lipid Catabolism and Increasing Lipogenesis in Black Carp (Mylopharyngodon piceus).

This study investigated the effects of dietary erucic acid (EA) on growth, lipid accumulation, antioxidant and immune abilities, and lipid metabolism in black carp fed six diets containing varying levels of EA (0.00%, 0.44%, 0.81%, 1.83%, 2.74%, and 3.49%), for 8 weeks. Results showed that fish fed the 3.49% EA diet exhibited lower weight gain, compared to those fed the 0.81% EA diet. In a dose-dependent manner, the serum triglycerides and total cholesterol were significantly elevated in the EA groups. The 1.83%, 2.74%, and 3.49% levels of EA increased alanine aminotransferase and aspartate aminotransferase activities, as well as decreased acid phosphatase and alkaline phosphatase values compared to the EA-deficient group. The hepatic catalase activity and transcriptional level were notably reduced, accompanied by increased hydrogen peroxide contents in the EA groups. Furthermore, dietary EA primarily increased the C22:1n-9 and C20:1n-9 levels, while decreasing the C18:0 and C18:1n-9 contents. In the EA groups, expressions of genes, including hsl, cpt1a, cpt1b, and ppara were downregulated, whereas the fas and gpat expressions were enhanced. Additionally, dietary EA elevated the mRNA level of il-1β and reduced the expression of il-10. Collectively, high levels of EA (2.74% and 3.49%) induced lipid accumulation, reduced antioxidative and immune abilities in black carp by inhibiting lipid catabolism and increasing lipogenesis. These findings provide valuable insights for optimizing the use of rapeseed oil rich in EA for black carp and other carnivorous fish species.

Involvement of ROS and calcium ions in developing heat resistance and inducing antioxidant system of wheat seedlings under melatonin's effects.

The stress-protective effect of melatonin (N-acetyl-5-methoxytryptamine) on plant cells is mediated by key signaling mediators, in particular calcium ions and reactive oxygen species (ROS). However, the links between changes in calcium and redox homeostasis and the formation of adaptive responses of cultivated cereals (including wheat) to the action of high temperatures have not yet been studied. In the present study, we investigated the possible involvement of ROS and calcium ions as signaling mediators in developing heat resistance in wheat (Triticum aestivum L.) seedlings and activating their antioxidant system. Treatment of 3-day-old etiolated seedlings with melatonin solutions at concentrations 0.01-10µM increased their survival after exposure to 45°C for 10min. The most significant stress-protective effect was exerted by melatonin treatment at 1µM concentration. Under the influence of melatonin, a transient enhancement of superoxide anion radical (O2•-) generation and an increase in hydrogen peroxide content were observed in roots, with a maximum at 1h. Four hours after treatment with melatonin, the activity of catalase and guaiacol peroxidase increased in roots, while the activity of superoxide dismutase did not change significantly. After exposure to 45°C, the activity of catalase and guaiacol peroxidase was higher in the roots of melatonin-treated wheat seedlings, and the indices of ROS generation, content of the lipid peroxidation product malonic dialdehyde, and cell membrane damage were lower than in control seedlings. Melatonin-induced changes in root ROS generation and antioxidant enzyme activities were eliminated by pretreatment with the hydrogen peroxide scavenger dimethylthiourea (DMTU), NADPH oxidase inhibitor imidazole, and calcium antagonists (the extracellular calcium chelator EGTA and phospholipase C inhibitor neomycin). Treatment with DMTU, imidazole, EGTA, and neomycin also abolished the melatonin-induced increase in survival of wheat seedlings after heat stress. The role of calcium ions and ROS, generated with the participation of NADPH oxidase, as signaling mediators in the melatonin-induced antioxidant system and heat stress resistance of wheat seedlings have been demonstrated.

Quantifying redox transcription factor dynamics as a tool to investigate redox signalling

A critical feature of the cellular antioxidant response is the induction of gene expression by redox-sensitive transcription factors. In many cells, activating these transcription factors is a dynamic process involving multiple redox steps, but it is unclear how these dynamics should be measured. Here, we show how the dynamic profile of the Schizosaccharomyces pombe Pap1 transcription factor is quantifiable by three parameters: signal amplitude, signal time and signal duration. In response to increasing hydrogen peroxide concentrations, the Pap1 amplitude decreased while the signal time and duration showed saturable increases. In co-response plots, these parameters showed a complex, non-linear relationship to the mRNA levels of four Pap1-regulated genes. We also demonstrate that hydrogen peroxide and tert-butyl hydroperoxide trigger quantifiably distinct Pap1 activation profiles and transcriptional responses. Based on these findings, we propose that different oxidants and oxidant concentrations modulate the Pap1 dynamic profile, leading to specific transcriptional responses. We further show how the effect of combination and pre-exposure stresses on Pap1 activation dynamics can be quantified using this approach. This method is therefore a valuable addition to the redox signalling toolbox that may illuminate the role of dynamics in determining appropriate responses to oxidative stress.

Transcriptome and metabolome analysis of preharvest internal browning in Nane plum fruit caused by high temperature

The preharvest internal browning of Nane plum fruit, with no visible effects on the appearance of the fruit, has become a serious problem in recent years in its production area in Guangdong Province, China. This study investigated the effects of environmental factors, including temperature, on Nane plum internal browning. Plum orchards at different elevations with different incidences of internal browning were selected. Using fruits with different internal browning incidence levels, the internal browning mechanism was analyzed with transcriptome and metabolome analyses. The results revealed decreased internal browning at high altitudes. Shading treatment significantly reduced internal browning, whereas bagging and insect-proof net-covering treatments significantly increased internal browning. Because bagging and net coverings increase the local ambient temperature, the findings suggest that high temperature is an important factor influencing the internal browning of Nane plum. The metabolome experiments showed that with increased internal browning, the levels of phenolic hydroxyls such as catechol increased, with simultaneous increases in hydrogen peroxide content and oxidase activity. It can be speculated that the oxidation of phenolic hydroxyl substances is the main cause of the preharvest browning of Nane plum. Transcriptome analysis revealed the increased expression of calcium signaling-related and downstream effector genes and indicated an important role of calcium in internal browning, possibly due to its increased content in the fruit. Further, with increasingly serious internal browning, genes related to photosynthesis were down-regulated, while genes related to senescence were up-regulated, thus suggesting the up-regulation of the process of cell senescence during internal browning. In conclusion, heat stress should be eliminated to reduce preharvest internal browning in Nane plum.

Metabolic perturbation studies using a Nash Equilibrium model of liver machine perfusion: modeling oxidative stress and effect of glutathione supplementation

The current clinical standard of Static Cold Storage (SCS) which involves preservation on ice (about +4°C) in a hypoxic state limits storage to a few hours for metabolically active tissues such as the liver and the heart. This period of hypoxia during can generate superoxide and other free radicals from purine metabolism, a well-established component of ischemia/reperfusion injury (IRI). Machine perfusion is at the cutting edge of organ preservation, which provides a functional, oxygenated preservation modality that can avoid/attenuate IRI. In clinical application, perfusion usually follows a period of SCS. This presentation of oxygen following hypoxia can lead to superoxide and hydrogen peroxide generation, but machine perfusion also allows manipulation of the temperature profiles and supply of antioxidant treatments, which could be used to minimize such issues. However, metabolomic data is difficult to gather, and there are currently no mathematical models present to allow rational design of experiments or guide clinical practice. In this article, the effects of a gradual warming temperature policy and glutathione supplementation to minimize oxidative stress are studied. An optimal gradual warming temperature policy for mid-thermic machine perfusion of a liver metabolic model is determined using a combination of Nash Equilibrium and Monte Carlo optimization. Using this optimal gradual warming temperature policy, minimum GSH requirements to maintain hydrogen peroxide concentrations in the normal region are calculated using a different Monte Carlo optimization methodology. In addition, the dynamic behavior of key metabolites and cofactors are determined. Results show that the minimum GSH requirement increases and that the ratio of GSH/GSSG decreases with increasing hydrogen peroxide concentration. In addition, at high concentrations of hydrogen peroxide it is shown that cytochrome C undergoes dysfunction leading to a decrease in useful oxygen consumption and ATP synthesis from the electron transport chain and an overall reduction in the energy charge for the liver cells.

Chronic effects induced by zinc oxide nanoparticles against larvae of the northern house mosquito Culex pipiens (Diptera: Culicidae)

It is estimated that up to a million person are subject to death every year from mosquito-borne diseases. To avoid the epidemic situations arising from mosquito-borne diseases, it is necessary to reduce the mosquito populations. Challenges against efficient mosquito management are mainly related to emergence of insecticide resistance leading to increased need for the development of alternative methods. Ideal insecticides cause permanent impacts on the target insects in order to ensure powerful insecticidal effect. This study hypothesized that the impact of zinc oxide nanoparticles (ZnONPs) on the larvae of Culex pipiens Linnaeus, 1758 (Diptera: Culicidae) mosquito is irreversible and chronic. The first instar C. pipiens larvae were treated with a sublethal concentration (LC20, 0.24 g/L) of ZnONPs for 72 h and then allowed to recover for additional 72 h. Following the recovery period, the changes in zinc accumulation, growth rate, gut ultrastructure, biochemical changes in the hydrogen peroxide, antioxidant and detoxification enzymes were recorded and compared between recovered larvae and untreated (control). Recovered larvae showed significant increase in the accumulated zinc and reduced growth rate by about 50% compared to untreated (control). Furthermore, the ultrastructure of the alimentary canal epithelium showed several forms of pathological signs in different parts of the midgut of recovered larvae. Treatment with ZnONPs induced oxidative stress (OS) which appeared in the form of significant increase in hydrogen peroxide concentration. In response to OS, insects activate the detoxification system to get rid of the toxic nanoparticles. The detoxification enzyme alkaline phosphatase (ALP) and the antioxidant enzyme glutathione peroxidase (GPX) were inhibited while superoxide dismutase (SOD) was activated against ZnONPs toxicity. Additionally, recovered larvae didn’t show differences in the catalase activity from untreated control. These results verified that ZnONPs induce chronic impacts on C. pipiens larvae suggesting that it can be used in their management via direct application in standing water sources including accumulated rains and swimming pools.

ISFET Fabrication and Characterization for Hydrogen Peroxide sensing

This work presents the Ion-Sensitive Field Effect Transistor (ISFET) fabrication and electrical characterization for hydrogen peroxide sensing. Two configurations were set up to evaluate the devices sensitivity to the concentration of the solution. First, measurements with one electrode in the sample solution (contained over the gate area) were performed, but the results may not be directly related to the characteristics of the solution, due to the prevalence of secondary effects. The second method, using two electrodes in the sample solution, shows a higher sensitivity at increasing hydrogen peroxide concentrations, in smallest intervals when compared to measurements with one electrode.

In vitro biomedical corrosion and enzyme activity inhibition on modified Cu-Zn-Al bioalloy

Abstract The amperometric biosensor was created using a flat sheet of the Cu-Zn-Al shape memory alloy, with a shiny surface and uniform thickness below 1 mm. The high biocompatibility and a large specific surface area for enzyme loading are evaluated. In vitro biomedical corrosion testing of samples revealed successful immobilization of catalase, which has undergone quasi-reversible electron transfer from the surface and saline solution. A catalase that had been immobilized retained its basic structure and bioactivity and demonstrated a remarkable electrocatalytic response to hydrogen peroxide reduction. The reduction of hydrogen peroxide on the catalase-modified Cu-25.38Zn-3.3Al alloy was investigated using hydrodynamic amperometry in both the absence and presence of l-cysteine and K2[B3O3F4OH] inhibitors. Catalytic reduction currents have increased as a result of the gradual increase in hydrogen peroxide concentration. The study on enzyme activity inhibition has shown a lower corrosion rate of catalase-modified bioalloy than the initial sample because inhibitor ions occupy all sites of the immobilized enzyme.

Cheap and Mass-Producible Electrochemical Sensor of Hydrogen Peroxide

Abstract Hydrogen peroxide is present naturally in any living cell. Although hydrogen peroxide concentration in cell is strictly regulated during normal metabolism, several human diseases lead to increased hydrogen peroxide concentration in body fluids. It is beneficial to monitor hydrogen peroxide levels in human body for early disease diagnostics. This can be done by creation of electronic device, which will use electrochemical sensor in order to perform automated hydrogen peroxide concentration measurement in a sample. The aim of the research is to use printed circuit board (PCB) technology in order to create a replaceable electrochemical hydrogen peroxide sensor that could be cheaply mass-produced to enable further development of automated health diagnostics device.

The mechanism of oxidative stress in keloid fibroblasts and the experimental study of early application of angiotensin-converting enzyme inhibitor.

Objective To investigate the protective effects of an angiotensin-converting enzyme inhibitor after inducing oxidative stress on keloid fibroblasts. Methods Primary keloid fibroblasts were isolated and cultured by enzyme digestion combined with the tissue adhesion method in vitro, and the third to fifth generations of cells were selected for the experiment. For 24 hours, keloid fibroblasts were treated with different concentrations of hydrogen peroxide. Different concentrations of angiotensin-converting enzyme inhibitor were added to the keloid fibroblast culture medium, and then the cells were treated with hydrogen peroxide for 24 hours. Results With the increase of hydrogen peroxide concentration, the growth of keloid fibroblasts was inhibited and the levels of malondialdehyde, superoxide dismutase, and reactive oxygen species increased gradually, accompanied by an increase in the expression of nicotinamide adenine dinucleotide phosphate oxidase and collagen I mRNA. The expression of nicotinamide adenine dinucleotide phosphate oxidase-mRNA in keloid fibroblasts and the formation of reactive oxygen species in keloid fibroblasts were induced by different concentrations of angiotensin II, and the most significant effect was at 10-5 mmol/mL. The effects of diphenyleneiodonium chloride (NOX inhibitor), N-acetylcysteine (reactive oxygen species inhibitor) and nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) RNA treatment on angiotensin II-induced nicotinamide adenine dinucleotide phosphate oxidase and collagen I increased significantly. Hydrogen peroxide and angiotensin II alone or combined can induce NADPH oxidase and reactive oxygen species expression in keloid fibroblasts. When the angiotensin-converting enzyme inhibitor was added, the expression of NADPH oxidase and reactive oxygen species in keloid induced by hydrogen peroxide and angiotensin II could be inhibited. Conclusion Oxidative stress can lead to increased expression of reactive oxygen species, NADPH oxidase and collagen I in keloid fibroblasts, suggesting oxidative stress mediates the migration of human keloid fibroblasts and extracellular matrix synthesis.

New insight into the mechanism of ferric hydroxide-based heterogeneous Fenton-like reaction.

The heterogeneous Fenton-like reaction (HeFR) has always been a research focus for environmental applications. However, it has long been difficult to reach a consensus on the reaction mechanism because the process of metal ions dissolution and its role were not well understood. In this paper, we propose the courses of organics-mediated coordination or/and reduction dissolution of ferric hydroxide to initiate the autocatalytic kinetics of phenol degradation and illustrate it through density functional theory (DFT) and experiments. With the increase of hydrogen peroxide concentration, the degradation of phenol changes from autocatalytic kinetics to first-order kinetics. Furthermore, a novel "limit segmentation method" initiated by us indicates that homogeneous reaction plays a decisive role in the phenol degradation process. The dominant roles of the reactive organics in both iron dissolution and the iron cycle and of the homogeneous reaction in the whole degradation process in the ferric hydroxide-based HeFR system are brand-new insights that pave the pathway for future research.

Pterostilbene Confers Protection against Diquat-Induced Intestinal Damage with Potential Regulation of Redox Status and Ferroptosis in Broiler Chickens.

Oxidative stress causes damage to macromolecules, including proteins, DNA, and lipid, and has been recognized as a crucial driver of the onset and progression of several intestinal disorders. Pterostilbene, one of the natural antioxidants, has attracted considerable attention owing to its multiple biological activities. In the present study, we established an oxidative stress model in broiler chickens via injection with diquat to investigate whether pterostilbene could attenuate diquat-induced intestinal damage and reveal the underlying mechanisms. We found that diquat-induced decreases in the activities of superoxide dismutase and glutathione peroxidase and the level of reduced glutathione and the increase in hydrogen peroxide content in plasma and jejunum were significantly alleviated by pterostilbene (P < 0.05). Pterostilbene supplementation also decreased intestinal permeability and jejunal apoptosis rate, improved jejunal villus height and the ratio of villus height to crypt depth, and promoted the transcription and translation of jejunal tight junction proteins occludin and zona occludens 1 in diquat-challenged broilers (P < 0.05). Furthermore, pterostilbene reversed diquat-induced mitochondrial injury in the jejunum, as indicated by the decreased reactive oxygen species level and elevated activities of superoxide dismutase 2 and mitochondrial respiratory complexes (P < 0.05). Importantly, administering pterostilbene maintained iron homeostasis, inhibited lipid peroxidation, and regulated the expression of the markers of ferroptosis in the jejunum of diquat-exposed broilers (P < 0.05). The nuclear factor erythroid 2-related factor 2 signaling pathway in the jejunum of diquat-exposed broilers was also activated by pterostilbene (P < 0.05). In conclusion, our study provides evidence that pterostilbene alleviates diquat-induced intestinal mucosa injury and barrier dysfunction by strengthening antioxidant capacity and regulating ferroptosis of broiler chickens.

Influence of water matrix components and peroxide sources on the transformation products and toxicity of tebuthiuron under UVC-based advanced oxidation processes

Coupling of UV-C irradiation to different peroxides (H2O2, S2O82− and HSO5−) has great potential to degrade persistent organic compounds due to the formation of HO• or SO4•– species. However, an in-depth comparison between the performance of different UV-C/peroxide processes as a function of (i) target compound degradation, (ii) generated transformation products and (iii) lethal/sub lethal toxicity effects has not yet been performed. To this end a comparison study was carried out to evaluate the effectiveness of different UV-C/peroxide processes using the herbicide tebuthiuron (100 or 500 μg L−1) as a model pollutant. TBH degradation experiments were performed at lab-scale in real municipal wastewater treatment plant effluent and distilled water. Faster degradation occurred by increasing peroxide concentration from 735 to 2206 μmol L−1 in the municipal wastewater treatment plant effluent, mainly for S2O82−. Experiments performed in the presence of peroxide trapping agents – HO• and SO4•– (methoxibenzene) or HO• (2-propanol) – revealed that oxidation in the UV-C/S2O82− system occurs mainly through SO4•–. Lower toxicity for the MWWTP effluent was obtained after oxidative treatments using hydrogen peroxide or monopersulfate as oxidants which react mainly through HO• radicals. Two mechanistic pathways were proposed for tebuthiuron degradation: (i) hydrogen abstraction by HO• (H2O2 and HSO5−) and (ii) electron transfer by SO4•– (S2O82−). In addition, one unprecedented transformation product was identified. In conclusion, results emphasize the relevance of comparing the degradation of toxic compounds in the presence of different peroxide sources and matrices and simultaneouly evaluating responses chemical and biological endpoints.

Suppression Effects of Excessively Expressed Gene BCL-2 in Cell Lines of Prostate Cancer

Abstract The aim of this study was to construct two plasmid-specific shRNA transcripts of the bcl-2 gene in order to prepare for reverse of cell apoptosis. The plasmid was designed according to a previously published sequence of interfering RNA following an appropriate reference, using appropriate software. By annulling complementary oligonucleotides, double-stranded inserts were formed. Recombinant shRNA-encoding plasmids were constructed by digestion of psiRNA-x7SKGFPzeo plasmid (psiRNA-x7SKGFPzeo, with restrictive endonuclease BbsI electrophoresis in ultra-pure agarose with low melting point (LMP-Agarose). For each of the constructs, a suitable double-stranded insert downstream of x7SK (strong RNA III promoter) with T4 DNA ligase was cloned. The control plasmid psiRNAScr was used directly for transformation. The PC-3 cell lines were transfected with 2 plasmids, psiRNA-Bcl-2 and psiRNAScr to suppress the bcl-2 gene construct. The results have shown that the lowest level of bcl-2 genes was 48 h, and even lower 72 h after the transfer, and the mRNA levels returned to normal in 120 h. An increase in the percentage of cells with spontaneous apoptosis has been observed with successful inhibition of the bcl-2 gene. The induction of apoptosis in transfected cells increased the percentage of necrotic cells proportionally. The percentage of apoptotic cells transfected with psiRNA-bcl-2 plasmid increased proportionally to the increase of hydrogen peroxide concentration. The transfection of the PC-3 cell line from prostate cancer with constructed shRNA plasmid has induced suppression of bcl-2 gene expression versus control Scr plasmid. Suppression of bcl-2 gene expression significantly increased cell sensitivity to apoptosis induction.

Synthesis of perbutyric acid with amberlyst catalyst in a continuous microreactor

Perbutyric acid is an important organic compound, which is effective against bacterial spores, viruses, and other microbes as a disinfectant and used in chemical processing and bleaching. Perbutyric acid is having large applications in oil and chemical industries because of its -goodoxidizing properties. The present article reports about the continuous production of Perbutyric acid in a Teflon spiral capillary microreactor. Butyric acid and hydrogen peroxide are used as reactants in the presence and absence of heterogeneous catalyst amberlyst15 hydrogen. Microreactors provide large surface area and safely handle unstable or dangerous materials. In microreactors, heat and mass transfer rates are higher and rapid mixing occurs because of their unique transport capabilities. So the present investigation focuses on understanding the effect of different parameters like temperature, the concentration of hydrogen peroxide and catalyst on the formation of Perbutyric acid. The results revealed the optimum conditions for 56.2% conversion of butyric acid at 90 °C temperature with 30 w/v% of hydrogen peroxide, 6 wt% of concentration of catalyst and 8 min of residence time. It was observed that the reaction rate increased with increase in hydrogen peroxide concentration. Further it could be concluded that the solid catalyst provides higher activity, which leads to the highest formation of Perbutyric acid in short residence times.

Production of performic acid through a capillary microreactor by heterogeneous catalyst

Abstract Microreactors are small in size with significant heat and mass transfer. Performic acid (PFA) is an important organic compound. It has broad applications in food, oil and chemical industries because of its oxidizing properties. In the present work PFA is produced in a continuous flow Teflon spiral capillary microreactor. The PFA is produced with and without a heterogeneous catalyst. The formic acid (FA) and hydrogen peroxide (HP) are the reactants to produce the PFA. It is a reversible reaction. The aim of the present work to monitor the consequence of hydrogen peroxide concentration, temperature and heterogeneous catalyst (Amberlite) for conversion of the FA. The experimental results showed that the formation of the PFA is effected with increase in hydrogen peroxide concentration, percentage of catalyst and temperature. The PFA formed within short residence time by the use of solid catalyst. The heterogeneous catalysts are better in decreasing corrosion and segregation of the catalyst compared to homogeneous catalysts. The best conditions for the PFA synthesis reaction were noted that 10 min residence time, 30 w/v% of HP, 6 wt% of catalyst concentration based on formic acid and 30 °C. Hence, the maximum concentration of the PFA was recorded 2.8 mol/L (XFA = 39.4%)

Duckweed Potential for the Phytoremediation of Linear Alkylbenzene Sulfonate (LAS): Identification of Some Intermediate Biodegradation Products and Evaluation of Antioxidant System.

Duckweed (Lemna minor L.) has a high potential for wastewater treatment. Here, its capability for bioremoval of linear alkylbenzene sulfonate (LAS) as one of the primary contaminants of water resources was evaluated. The effect of some operational parameters on surfactant removal efficiency was determined. Also, the impact of LAS on several physiological responses of Lemna was investigated. LAS remediation efficiency of L. minor was elevated with increasing LAS concentration, duckweed weight, and temperature. Furthermore, the optimal pH for removal was 7-8.5. The benzenesulfonate ring and five homologs of sulfophenyl carboxylate were identified as intermediates in the LAS degradation pathway. A decrease in relative growth rate and pigment contents was observed by increasing LAS concentration. In contrast, an increase in hydrogen peroxide content and electrolyte leakage indicated oxidative stress by LAS. Induction of enzymatic/non-enzymatic antioxidants was observed during the surfactant remediation process, indicating their role in overcoming free radicals generated under surfactant stress.

Effects of spermidine on germination of Salix spp. after storage under controlled conditions

Willows produce fast germinating and short-lived seeds, difficult to store in the long-term under controlled conditions. The aim of this study was to examine the feasibility of storage of three Salix spp. at controlled temperatures (3°, −10°, −196 °C). We also analyzed the effect of spermidine (Spd) as an antioxidant factor in desiccated seeds. Collected seeds were either desiccated or hydrated to obtain 10 levels of moisture content (between app. 4% and 2%) and subjected to storage at temperatures 3°, −10°, or −196 °C (liquid nitrogen; LN). After two months, seeds were germinated on the light at 20 °C. Seeds desiccated below a safe range of moisture content were further tested and germinated on filter paper with additions of 0.25 mM Spd solution. After 7 days seedlings were examined for hydrogen peroxide content (H2O2) and total antioxidant capacity (TAC). Fresh seeds of three Salix species: Persian willow (S. aegyptiaca L.), heartleaf willow (S. cordata Michx.) and crack willow (S. ×fragilis L.) were successfully stored at temperature −10° and −196 °C for two months. After cryopreservation seed of S. aegyptiaca, S. cordata, and S. ×fragilis germinated without viability loss in moisture content ranging from 4.4–15.9%, 6.4–18.5%, and 7.1–11.5% respectively. The addition of Spd during germination of desiccated seed did not affect germination capacity. However, seedlings of S. aegyptiaca had lower hydrogen peroxide content in comparison with control (germination on water). Seedlings of S. cordata showed an increase in hydrogen peroxide content in control after storing in LN. In seedlings of Crack willow Spd increased hydrogen peroxide content. Seeds of tested species differ in response to storage conditions. Salix seeds can be stored successfully for two months at −10° or −196 °C without losing viability in the safe range of moisture content. Storing at 3 °C can be used for storage in the narrower range of seeds’ moisture content, however, seedlings stored at this temperature produce a higher level of reactive oxygen species. Germinating seeds in Spd did not increase their germination, however in S. aegyptiaca and S. cordata decreased hydrogen peroxide content