scholarly journals The role of polysaccharides and diatom exudates in the redox cycling of Fe and the photoproduction of hydrogen peroxide in coastal seawaters

2009 ◽  
Vol 6 (4) ◽  
pp. 7789-7819 ◽  
Author(s):  
S. Steigenberger ◽  
P. J. Statham ◽  
C. Völker ◽  
U. Passow
Keyword(s):  
Hydrogen Peroxide ◽  
Coastal Waters ◽  
Phaeodactylum Tricornutum ◽  
Laboratory Experiments ◽  
Uv Light ◽  
H2o2 Production ◽  
Initial Value ◽  
Photochemical Formation ◽  
Algal Exudates

Abstract. The effect of artificial acidic polysaccharides (PS) and exudates of Phaeodactylum tricornutum on the half-life of Fe(II) in seawater was investigated in laboratory experiments. Strong photochemical hydrogen peroxide (H2O2) production of 5.2 to 10.9 nM (mg C)−1 h−1 was found in the presence of PS and diatom exudates. Furthermore when illuminated with UV light the presence of algal exudates had a net stabilising effect on ferrous iron in seawater (initial value 100 nmol L−1) above that expected from oxidation kinetics. In the dark the PS gum xanthan showed no stabilising effect on Fe(II). The photochemical formation of superoxide (O2−) in presence of diatom exudates and its reducing effect on Fe(III) appears to result in greater than expected concentrations of Fe(II). A model of the photochemical redox cycle of iron incorporating these processes supported the observed data well. Diatom exudates seem to play an important role for the photochemistry of iron in coastal waters.

scholarly journals The role of polysaccharides and diatom exudates in the redox cycling of Fe and the photoproduction of hydrogen peroxide in coastal seawaters

2010 ◽  
Vol 7 (1) ◽  
pp. 109-119 ◽  
Author(s):  
S. Steigenberger ◽  
P. J. Statham ◽  
C. Völker ◽  
U. Passow
Keyword(s):  
Hydrogen Peroxide ◽  
Coastal Waters ◽  
Phaeodactylum Tricornutum ◽  
Laboratory Experiments ◽  
Uv Light ◽  
H2o2 Production ◽  
Initial Value ◽  
Photochemical Formation ◽  
Algal Exudates

Abstract. The effect of artificial acidic polysaccharides (PS) and exudates of Phaeodactylum tricornutum on the half-life of Fe(II) in seawater was investigated in laboratory experiments. Strong photochemical hydrogen peroxide (H2O2) production of 5.2 to 10.9 nM (mg C)−1 h−1 was found in the presence of PS and diatom exudates. Furthermore when illuminated with UV light the presence of algal exudates had a net stabilising effect on ferrous iron in seawater (initial value 100 nmol L−1) above that expected from oxidation kinetics. In the dark the PS gum xanthan showed no stabilising effect on Fe(II). The photochemical formation of superoxide (O2−) in the presence of diatom exudates and its reducing effect on Fe(III) appears to result in greater than expected concentrations of Fe(II). A model of the photochemical redox cycle of iron incorporating these processes supported the observed data well. Diatom exudates seem to have the potential to play an important role for the photochemistry of iron in coastal waters.

Photochemical Formation of Hydrogen Peroxide in Atmospheric Droplets: The Role of Iron, Oxalate, and Trace Metals on the H2O2-Production

2007 ◽  
pp. 346-362 ◽  
Author(s):  
Jörg Wohlgemuth ◽  
Dagmar Pffflin ◽  
Wolfgang Jaeschke ◽  
Felix Deutsch ◽  
Peter Hoffmann ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Trace Metals ◽  
H2o2 Production ◽  
Photochemical Formation ◽  
Iron Oxalate

scholarly journals UV-Light-Induced Water Condensation in Air and the Role of Hydrogen Peroxide

2014 ◽  
Vol 87 (5) ◽  
pp. 593-602 ◽  
Author(s):  
Keitaro Yoshihara ◽  
Yosuke Sakamoto ◽  
Masahiro Kawasaki ◽  
Yoshiki Takatori ◽  
Shungo Kato ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Uv Light ◽  
Water Condensation

scholarly journals Investigating the role of COQ8B in aortic smooth muscle cells.

2018 ◽  
Vol 1 (1) ◽  
Author(s):  
Henry Stadler ◽  
Stephanie Ware ◽  
Benjamin Landis
Keyword(s):  
Hydrogen Peroxide ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Quantitative Polymerase Chain Reaction ◽  
Genetic Modifier ◽  
Muscle Cells ◽  
Negative Control ◽  
H2o2 Production ◽  
Cardiac Transplant

Background and Hypothesis:  Thoracic aortic aneurysm (TAA) is an aortopathy characterized by aortic enlargement and life-threatening complications such as aortic dissection and sudden cardiac death. Previous studies identified COQ8B as a candidate genetic modifier of TAA severity. COQ8B is important for mitochondrial biosynthesis of coenzyme Q, but its precise functions are not defined. We hypothesize that alteration of COQ8B influences TAA pathogenesis via energy and oxidant metabolism pathways.  Experimental Design:  Smooth muscle cells (SMCs) were cultured directly from leftover healthy aortic tissues acquired during cardiac transplant operations. At confluence of 50-70%, cells were transfected with siRNA targeting COQ8B or a non-targeting negative control siRNA. Gene expression was measured using real-time quantitative polymerase chain reaction (RT-qPCR).  Production of the reactive oxygen species hydrogen peroxide (H2O2) was measured using the fluorescence-based Amplex Red Hydrogen Peroxide Assay (Invitrogen) in basal growth medium.   Results:  Expression of COQ8B decreased by approximately 75% to 85% at 48 hours following siRNA transfection compared with negative control.  This was associated with approximately 1.5 fold upregulation of the SMC contractile gene CNN1 (p<0.05).  Knockdown of COQ8B did not appear to alter H2O2 production measured at timepoints of 48 or 72 hours.   Conclusion and Impact:  Based on these preliminary data, decreased COQ8B expression appears to alter the contractile phenotype of SMCs but may not significantly influence extracellular levels of H2O2 under basal conditions.  Exogenous activation of pathways important for TAA pathogenesis may be required to elucidate the role of COQ8B. Ultimately, this work may lead to improved clinical approaches. 

scholarly journals Peroxisomal Hydrogen Peroxide Metabolism and Signaling in Health and Disease

2019 ◽  
Vol 20 (15) ◽  
pp. 3673 ◽  
Author(s):  
Lismont ◽  
Revenco ◽  
Fransen
Keyword(s):  
Hydrogen Peroxide ◽  
Molecular Mechanisms ◽  
Signaling Network ◽  
H2o2 Production ◽  
Peroxisomal Enzyme ◽  
Pathological Conditions ◽  
Health And Disease ◽  
Precise Role ◽  
Insight Into

Hydrogen peroxide (H2O2), a non-radical reactive oxygen species generated during many (patho)physiological conditions, is currently universally recognized as an important mediator of redox-regulated processes. Depending on its spatiotemporal accumulation profile, this molecule may act as a signaling messenger or cause oxidative damage. The focus of this review is to comprehensively evaluate the evidence that peroxisomes, organelles best known for their role in cellular lipid metabolism, also serve as hubs in the H2O2 signaling network. We first briefly introduce the basic concepts of how H2O2 can drive cellular signaling events. Next, we outline the peroxisomal enzyme systems involved in H2O2 metabolism in mammals and reflect on how this oxidant can permeate across the organellar membrane. In addition, we provide an up-to-date overview of molecular targets and biological processes that can be affected by changes in peroxisomal H2O2 metabolism. Where possible, emphasis is placed on the molecular mechanisms and factors involved. From the data presented, it is clear that there are still numerous gaps in our knowledge. Therefore, gaining more insight into how peroxisomes are integrated in the cellular H2O2 signaling network is of key importance to unravel the precise role of peroxisomal H2O2 production and scavenging in normal and pathological conditions.

scholarly journals Nitric Oxide and Hydrogen Peroxide Signaling in Extractive Shiraia Fermentation by Triton X-100 for Hypocrellin A Production

2020 ◽  
Vol 21 (3) ◽  
pp. 882
Author(s):  
Xin Ping Li ◽  
Yue Wang ◽  
Yan Jun Ma ◽  
Jian Wen Wang ◽  
Li Ping Zheng
Keyword(s):  
Nitric Oxide ◽  
Hydrogen Peroxide ◽  
H2o2 Production ◽  
No Production ◽  
Extractive Fermentation ◽  
Hypocrellin A ◽  
Cell Membrane Permeabilization ◽  
Rapid Generation ◽  
Triton X

Shiraia mycelial culture is a promising biotechnological alternative for the production of hypocrellin A (HA), a new photosensitizer for anticancer photodynamic therapy (PDT). The extractive fermentation of intracellular HA in the nonionic surfactant Triton X-100 (TX100) aqueous solution was studied in the present work. The addition of 25 g/L TX100 at 36 h of the fermentation not only enhanced HA exudation to the broth by 15.6-fold, but stimulated HA content in mycelia by 5.1-fold, leading to the higher production 206.2 mg/L, a 5.4-fold of the control on day 9. After the induced cell membrane permeabilization by TX100 addition, a rapid generation of nitric oxide (NO) and hydrogen peroxide (H2O2) was observed. The increase of NO level was suppressed by the scavenger vitamin C (VC) of reactive oxygen species (ROS), whereas the induced H2O2 production could not be prevented by the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), suggesting that NO production may occur downstream of ROS in the extractive fermentation. Both NO and H2O2 were proved to be involved in the expressions of HA biosynthetic genes (Mono, PKS and Omef) and HA production. NO was found to be able to up-regulate the expression of transporter genes (MFS and ABC) for HA exudation. Our results indicated the integrated role of NO and ROS in the extractive fermentation and provided a practical biotechnological process for HA production.

scholarly journals The use of marine microalgae for biotesting the waters of Sevastopol bays

2021 ◽  
pp. 35-42
Author(s):  
L.V. Stelmakh ◽  
◽  
N.P. Kovrigina ◽  
Keyword(s):  
Surface Waters ◽  
Coastal Waters ◽  
Phaeodactylum Tricornutum ◽  
Laboratory Experiments ◽  
The Black Sea ◽  
Depressing Effect ◽  
Summer Period ◽  
Taxonomic Affiliation ◽  
Multicellular Organisms ◽  
Microalgae Growth

For biotesting the marine environment, multicellular organisms are often used, primarily fish and their embryos. However, microalgae are still not used sufficiently enough for this purpose, the number of tested species is extremely limited. The aim of this work was to study the response of three species of planktonic microalgae to the complex pollution of the Black Sea coastal waters in the Sevastopol region and to assess the possibility of their application for biotesting. The studies were carried out on the diatom Phaeodactylum tricornutum and two dinoflagellates Prorocentrum cordatum and Gyrodinium fissum. To characterize the level of pollution of surface waters with organic substances, two indicators were used: BOС5 (biological oxygen consumption) and permanganate oxidizability. Evaluation of the effect of the water sample pollution on microalgae was carried out by the comparison between the coefficient of increase in the abundance of microalgae cells (Xk) in the experiment and the control one. Laboratory experiments carried out in the summer and autumn periods made it possible to reveal, in most cases, a weak depressing effect of the studied waters pollution on the microalgae growth. Occasionally, this effect reached a chronic level. In the summer period (in June), a stimulating effect of water pollution on the growth of dinoflagellates was observed, reaching the level of subacute level in 50% of cases. The necessity of using several types of microalgae of different taxonomic affiliation when performing biotesting of sea waters is highlighted.

ChemInform Abstract: UV-Light-Induced Water Condensation in Air and the Role of Hydrogen Peroxide

ChemInform ◽  
2014 ◽  
Vol 45 (31) ◽  
pp. no-no
Author(s):  
Keitaro Yoshihara ◽  
Yosuke Sakamoto ◽  
Masahiro Kawasaki ◽  
Yoshiki Takatori ◽  
Shungo Kato ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Uv Light ◽  
Water Condensation

Response of marine microalgae Phaeodactylum tricornutum, Prorocentrum cordatum and Gyrodinium fissum to complex pollution of Sevastopol bays (Black Sea)

2021 ◽  
Vol 48 ◽  
pp. 109-116
Author(s):  
Liudmila Stelmakh ◽  
Nela Kovrigina ◽  
Tatiana Gorbunova
Keyword(s):  
Black Sea ◽  
Coastal Waters ◽  
Phaeodactylum Tricornutum ◽  
Laboratory Experiments ◽  
Toxicity Assessment ◽  
Marine Microalgae ◽  
The Black Sea ◽  
Organic Substances ◽  
Taxonomic Affiliation ◽  
Concentration Levels

For the degrees of toxicity assessment within the Black Sea surface coastal waters near Sevastopol, laboratory experiments were performed on three marine microalgae species culture’s growth in water sampled on the three stations of the region from May to December 2020. The study has indicated, that in the majority of cases, insignificant inhibiting influences of the waters to diatom Phaeodactylum tricornutum Bohlin and insignificant stimulated effect to dinoflagellates Prorocentrum сordatum (Ostenfeld) J.D.Dodge and Gyrodinium fissum (Levander) Kofoid & Swezy were observed. Rarely this effect was characterized as chronic or subacute. The concentration levels of both stable and unstable forms of organic substances in the studied waters were estimated. The results of the testing of the water to determine its contamination using microalgae and analysis of the organic substances concentration levels in them, allowed the conclusion that the studied area should be classified as episodically polluted. Justification for the necessity to use several microalgae species of different taxonomic affiliation when performing marine water biotesting is provided in this study.

The role of copper ions in hydrogen peroxide bleaching: Their origin, removal, and effect on pulp quality

TAPPI Journal ◽  
2012 ◽  
Vol 11 (7) ◽  
pp. 37-46 ◽  
Author(s):  
PEDRO E.G. LOUREIRO ◽  
SANDRINE DUARTE ◽  
DMITRY V. EVTUGUIN ◽  
M. GRAÇA V.S. CARVALHO
Keyword(s):  
Hydrogen Peroxide ◽  
Copper Ions ◽  
Peroxide Bleaching ◽  
Metals Removal ◽  
Peroxide Decomposition ◽  
Equipment Corrosion ◽  
And Performance ◽  
And Control ◽  
Main Effects

This study puts particular emphasis on the role of copper ions in the performance of hydrogen peroxide bleaching (P-stage). Owing to their variable levels across the bleaching line due to washing filtrates, bleaching reagents, and equipment corrosion, these ions can play a major role in hydrogen peroxide decomposition and be detrimental to polysaccharide integrity. In this study, a Cu-contaminated D0(EOP)D1 prebleached pulp was subjected to an acidic washing (A-stage) or chelation (Q-stage) before the alkaline P-stage. The objective was to understand the isolated and combined role of copper ions in peroxide bleaching performance. By applying an experimental design, it was possible to identify the main effects of the pretreatment variables on the extent of metals removal and performance of the P-stage. The acid treatment was unsuccessful in terms of complete copper removal, magnesium preservation, and control of hydrogen peroxide consumption in the following P-stage. Increasing reaction temperature and time of the acidic A-stage improved the brightness stability of the D0(EOP)D1AP bleached pulp. The optimum conditions for chelation pretreatment to maximize the brightness gains obtained in the subsequent P-stage with the lowest peroxide consumption were 0.4% diethylenetriaminepentaacetic acid (DTPA), 80ºC, and 4.5 pH.

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