The beers’ lag time measured with the PBN (N-t-Butyl-α-phenylnitrone) spin trapping experiments coupled with EPR spectroscopy is related to their antioxidant capacity and shelf life. The effect on the lag time of the alcohol content of the beer (starting values, 9 and 13%) and PBN concentration (50 or 200 mM) was analyzed on three samples, a pilsner, a strong lager, and a blonde Ale heated at 60 °C to trigger the production of the 1-hydroxyethyl radical. The lag time was determined only for the strong lager beer, with the values depending on the experimental conditions, being higher when PBN had a lower concentration. The antioxidant activity of the three beers gave the following values: 0.9089 mL pilsner beer/mg DPPH, 0.8510 mL strong lager beer/mg DPPH, and 0.7184 mL blonde Ale beer/mg DPPH, indicating that the unsuccessful determination of the lag time was not due to stale beers. The EPR intensity of the PBN adduct after 150 min (I150) and the area under the curve (AUC) were also measured and related to the oxidative stability of beers. Further studies are needed to verify the influence of the heating temperature in samples that do not show a lag time at 60 °C.
用PBN（N-叔丁基-α-苯基硝酮）自旋捕获实验结合EPR光谱测定啤酒的滞后时间与啤酒的抗氧化能力和保质期有关。在三个样品上分析了啤酒酒精含量（起始值，9%和13%）和PBN浓度（50或200mM）对滞后时间的影响，即在60°C下加热以引发1-羟基乙基自由基产生的皮尔斯纳啤酒、浓啤酒和金色啤酒。滞后时间仅适用于浓啤酒，其值取决于实验条件，当PBN浓度较低时，滞后时间较高。三种啤酒的抗氧化活性分别为0.9089mL皮尔斯纳啤酒/mg DPPH、0.8510mL浓啤酒/mg DP PH和0.7184mL金色啤酒/mg D PH，表明滞后时间的测定不成功不是由于陈啤酒。还测量了150分钟后PBN加合物的EPR强度（I150）和曲线下面积（AUC），并与啤酒的氧化稳定性有关。需要进一步的研究来验证在60°C时没有显示滞后时间的样品中加热温度的影响。
{"title":"Lag Time Determinations in Beer Samples. Influence of Alcohol and PBN Concentration in EPR Spin Trapping Experiments","authors":"M. Porcu, A. Fadda, D. Sanna","doi":"10.3390/oxygen2040040","DOIUrl":"https://doi.org/10.3390/oxygen2040040","url":null,"abstract":"The beers’ lag time measured with the PBN (N-t-Butyl-α-phenylnitrone) spin trapping experiments coupled with EPR spectroscopy is related to their antioxidant capacity and shelf life. The effect on the lag time of the alcohol content of the beer (starting values, 9 and 13%) and PBN concentration (50 or 200 mM) was analyzed on three samples, a pilsner, a strong lager, and a blonde Ale heated at 60 °C to trigger the production of the 1-hydroxyethyl radical. The lag time was determined only for the strong lager beer, with the values depending on the experimental conditions, being higher when PBN had a lower concentration. The antioxidant activity of the three beers gave the following values: 0.9089 mL pilsner beer/mg DPPH, 0.8510 mL strong lager beer/mg DPPH, and 0.7184 mL blonde Ale beer/mg DPPH, indicating that the unsuccessful determination of the lag time was not due to stale beers. The EPR intensity of the PBN adduct after 150 min (I150) and the area under the curve (AUC) were also measured and related to the oxidative stability of beers. Further studies are needed to verify the influence of the heating temperature in samples that do not show a lag time at 60 °C.","PeriodicalId":74387,"journal":{"name":"Oxygen (Basel, Switzerland)","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41659656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Samrot, Sanjay Preeth Ram Singh, R. Deenadhayalan, Vinod Vincent Rajesh, Sathiyamoorthy Padmanaban, K. Radhakrishnan
The usage of nanoparticles became inevitable in medicine and other fields when it was found that they could be administered to hosts to act as oxidants or antioxidants. These oxidative nanoparticles act as pro-oxidants and induce oxidative stress-mediated toxicity through the generation of free radicals. Some nanoparticles can act as antioxidants to scavenge these free radicals and help in maintaining normal metabolism. The oxidant and antioxidant properties of nanoparticles rely on various factors including size, shape, chemical composition, etc. These properties also help them to be taken up by cells and lead to further interaction with cell organelles/biological macromolecules, leading to either the prevention of oxidative damage, the creation of mitochondrial dysfunction, damage to genetic material, or cytotoxic effects. It is important to know the properties that make these nanoparticles act as oxidants/antioxidants and the mechanisms behind them. In this review, the roles and mechanisms of nanoparticles as oxidants and antioxidants are explained.
{"title":"Nanoparticles, a Double-Edged Sword with Oxidant as Well as Antioxidant Properties—A Review","authors":"A. Samrot, Sanjay Preeth Ram Singh, R. Deenadhayalan, Vinod Vincent Rajesh, Sathiyamoorthy Padmanaban, K. Radhakrishnan","doi":"10.3390/oxygen2040039","DOIUrl":"https://doi.org/10.3390/oxygen2040039","url":null,"abstract":"The usage of nanoparticles became inevitable in medicine and other fields when it was found that they could be administered to hosts to act as oxidants or antioxidants. These oxidative nanoparticles act as pro-oxidants and induce oxidative stress-mediated toxicity through the generation of free radicals. Some nanoparticles can act as antioxidants to scavenge these free radicals and help in maintaining normal metabolism. The oxidant and antioxidant properties of nanoparticles rely on various factors including size, shape, chemical composition, etc. These properties also help them to be taken up by cells and lead to further interaction with cell organelles/biological macromolecules, leading to either the prevention of oxidative damage, the creation of mitochondrial dysfunction, damage to genetic material, or cytotoxic effects. It is important to know the properties that make these nanoparticles act as oxidants/antioxidants and the mechanisms behind them. In this review, the roles and mechanisms of nanoparticles as oxidants and antioxidants are explained.","PeriodicalId":74387,"journal":{"name":"Oxygen (Basel, Switzerland)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49304700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Hancock, Grace Russell, T. Craig, J. May, H. Morse, J. Stamler
Hydrogen gas (molecular hydrogen, H2) has significant effects in a range of organisms, from plants to humans. Many inert gases have been reported to have similar effects, and such responses may be most pronounced when cells are stressed. Xenon (Xe), for example, is a well-known anesthetic. The direct targets of these gases, in most cases, remain elusive. Myoglobin and hemoglobin are known for their roles in the transport of gases through coordinate interactions with metals (O2, NO, CO) and covalent modifications of thiols (NO, H2S) and amines (CO2). These are well exemplified in biotrophic reactions of NO with heme iron (to form iron nitrosyl heme) and cysteine (to form bioactive S-nitrosothiols) essential for tissue oxygenation. Here, we consider an alternative “third mode” of gas transport in what have been dubbed “Xenon pockets”, whereby inert gases may have functional effects. Many proteins have similar cavities, and possible effects include alterations in allosteric properties of proteins (potentially altering protein hydration). Here, it is suggested that similar to other inert gases, H2 also has biological effects by utilizing these protein structures. This ought to be investigated further, in a range of species, to determine if this is the mode of action of H2.
{"title":"Understanding Hydrogen: Lessons to Be Learned from Physical Interactions between the Inert Gases and the Globin Superfamily","authors":"J. Hancock, Grace Russell, T. Craig, J. May, H. Morse, J. Stamler","doi":"10.3390/oxygen2040038","DOIUrl":"https://doi.org/10.3390/oxygen2040038","url":null,"abstract":"Hydrogen gas (molecular hydrogen, H2) has significant effects in a range of organisms, from plants to humans. Many inert gases have been reported to have similar effects, and such responses may be most pronounced when cells are stressed. Xenon (Xe), for example, is a well-known anesthetic. The direct targets of these gases, in most cases, remain elusive. Myoglobin and hemoglobin are known for their roles in the transport of gases through coordinate interactions with metals (O2, NO, CO) and covalent modifications of thiols (NO, H2S) and amines (CO2). These are well exemplified in biotrophic reactions of NO with heme iron (to form iron nitrosyl heme) and cysteine (to form bioactive S-nitrosothiols) essential for tissue oxygenation. Here, we consider an alternative “third mode” of gas transport in what have been dubbed “Xenon pockets”, whereby inert gases may have functional effects. Many proteins have similar cavities, and possible effects include alterations in allosteric properties of proteins (potentially altering protein hydration). Here, it is suggested that similar to other inert gases, H2 also has biological effects by utilizing these protein structures. This ought to be investigated further, in a range of species, to determine if this is the mode of action of H2.","PeriodicalId":74387,"journal":{"name":"Oxygen (Basel, Switzerland)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45304544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Rogers, Ashleigh M. Davis, Ashley E. Rice, C. Ballmann
Beetroot juice (BRJ) is high in inorganic nitrate (NO3) which has been shown to enhance vascular function, cognition, and physical performance. Acute BRJ supplementation has been reported to enhance explosive resistance exercise performance and simple reaction time in diseased populations. However, it remains unknown if acute BRJ supplementation can enhance agility and reactive drills in healthy individuals, which are relevant to many sports. The purpose of this study was to investigate the effects of acute BRJ supplementation on simple reaction time and reactive agility performance. In a counterbalanced double-blinded manner, physically active males completed two trials each with a differing single-dose treatment: (1) Placebo (PL), (2) BRJ. Each treatment was consumed 2-hrs before experimental testing. Plasma Nitrate (NO3) and Nitrite (NO2) were measured via capillary blood sampling and colorimetric assay. Reaction time was assessed using a simple reaction time light test. Reactive agility was measured via a semi-circle drill and a get-up-and-go drill. All tests used FITLIGHT LED sensors to record response time. Each visit was separated by a 72-h washout period. Acute BRJ ingestion resulted in significantly greater plasma NO3 (p < 0.001) and NO2 (p = 0.008) compared to PL. BRJ significantly improved response time during the semi-circle drill (p = 0.011) and get-up and go drill (p = 0.027) compared to PL. No differences between treatments were observed for simple reaction time (p = 0.279). Collectively, these findings suggest that acute BRJ ingestion may improve reactive agility performance likely mediated by systemic increases in NO3/NO2. Future research is needed to investigate how these findings translate to game-play and sports competition.
{"title":"Effects of Acute Beetroot Juice Ingestion on Reactive Agility Performance","authors":"R. Rogers, Ashleigh M. Davis, Ashley E. Rice, C. Ballmann","doi":"10.3390/oxygen2040037","DOIUrl":"https://doi.org/10.3390/oxygen2040037","url":null,"abstract":"Beetroot juice (BRJ) is high in inorganic nitrate (NO3) which has been shown to enhance vascular function, cognition, and physical performance. Acute BRJ supplementation has been reported to enhance explosive resistance exercise performance and simple reaction time in diseased populations. However, it remains unknown if acute BRJ supplementation can enhance agility and reactive drills in healthy individuals, which are relevant to many sports. The purpose of this study was to investigate the effects of acute BRJ supplementation on simple reaction time and reactive agility performance. In a counterbalanced double-blinded manner, physically active males completed two trials each with a differing single-dose treatment: (1) Placebo (PL), (2) BRJ. Each treatment was consumed 2-hrs before experimental testing. Plasma Nitrate (NO3) and Nitrite (NO2) were measured via capillary blood sampling and colorimetric assay. Reaction time was assessed using a simple reaction time light test. Reactive agility was measured via a semi-circle drill and a get-up-and-go drill. All tests used FITLIGHT LED sensors to record response time. Each visit was separated by a 72-h washout period. Acute BRJ ingestion resulted in significantly greater plasma NO3 (p < 0.001) and NO2 (p = 0.008) compared to PL. BRJ significantly improved response time during the semi-circle drill (p = 0.011) and get-up and go drill (p = 0.027) compared to PL. No differences between treatments were observed for simple reaction time (p = 0.279). Collectively, these findings suggest that acute BRJ ingestion may improve reactive agility performance likely mediated by systemic increases in NO3/NO2. Future research is needed to investigate how these findings translate to game-play and sports competition.","PeriodicalId":74387,"journal":{"name":"Oxygen (Basel, Switzerland)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42897028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bacterial infestation of the male reproductive system with subsequent effects of bacteria on the structural integrity and functional activity of male gametes has become a significant factor in the etiology of male reproductive dysfunction. Bacteria may affect male fertility either by directly interacting with structures critical for sperm survival or indirectly by triggering a local immune response, leukocytospermia or reactive oxygen species (ROS) overproduction followed by oxidative stress development. This review aims to provide an overview of the currently available knowledge on bacteriospermia-associated sperm damage with a special emphasis on oxidative mechanisms underlying sperm deterioration caused by bacterial action. At the same time, we strive to summarize readily available alternatives to prevent or counteract alterations to spermatozoa caused by bacterial colonization of semen or by oxidative stress as an accompanying phenomenon of bacteriospermia.
{"title":"Oxidative Stress as an Underlying Mechanism of Bacteria-Inflicted Damage to Male Gametes","authors":"E. Tvrdá, F. Benko, M. Ďuračka","doi":"10.3390/oxygen2040036","DOIUrl":"https://doi.org/10.3390/oxygen2040036","url":null,"abstract":"Bacterial infestation of the male reproductive system with subsequent effects of bacteria on the structural integrity and functional activity of male gametes has become a significant factor in the etiology of male reproductive dysfunction. Bacteria may affect male fertility either by directly interacting with structures critical for sperm survival or indirectly by triggering a local immune response, leukocytospermia or reactive oxygen species (ROS) overproduction followed by oxidative stress development. This review aims to provide an overview of the currently available knowledge on bacteriospermia-associated sperm damage with a special emphasis on oxidative mechanisms underlying sperm deterioration caused by bacterial action. At the same time, we strive to summarize readily available alternatives to prevent or counteract alterations to spermatozoa caused by bacterial colonization of semen or by oxidative stress as an accompanying phenomenon of bacteriospermia.","PeriodicalId":74387,"journal":{"name":"Oxygen (Basel, Switzerland)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48655274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vasileios M. Pappas, D. Palaiogiannis, V. Athanasiadis, Theodoros G. Chatzimitakos, Eleni Bozinou, D. Makris, S. Lalas
In this study, the use of pulsed electric field (PEF) for the extraction of polyphenols from mature Elaeagnus pungens ‘Limelight’ leaves is discussed. Optimization of the main parameters that affect the extraction process was carried out. More specifically, the composition of the solvent (ethanol, water, and mixtures of the two at a 25% v/v step gradient) and the main PEF-related parameters (i.e., pulse duration, pulse period, and electric field intensity) was optimized. The obtained extracts were examined for their polyphenol content with the Folin–Ciocalteu assay and individual polyphenols were also assessed with high-performance liquid chromatography. The extracts obtained with PEF were compared to the extract compared without PEF, in terms of total polyphenols. According to the results, the optimum extraction parameters were found to be a pulse duration of 10 μs, a pulse period of 1000 μs, and an electric field intensity of 0.85 kV cm−1 after 20 min of extraction. The optimum solvent was found to be the 50% (v/v) ethanol/water mixture. The extract prepared under the optimum conditions was found to contain 58% more polyphenols compared with the extract prepared without PEF. Moreover, an increase of up to 92% was recorded for specific polyphenols. Based on the above, it was evidenced that the examined parameters influenced the recovery of polyphenols, suggesting that such parameters should be also examined in similar studies, in order to maximize the extraction yield of polyphenols.
{"title":"Optimization of Pulsed Electric-Field-Based Total Polyphenols’ Extraction from Elaeagnus pungens ‘Limelight’ Leaves Using Hydroethanolic Mixtures","authors":"Vasileios M. Pappas, D. Palaiogiannis, V. Athanasiadis, Theodoros G. Chatzimitakos, Eleni Bozinou, D. Makris, S. Lalas","doi":"10.3390/oxygen2040035","DOIUrl":"https://doi.org/10.3390/oxygen2040035","url":null,"abstract":"In this study, the use of pulsed electric field (PEF) for the extraction of polyphenols from mature Elaeagnus pungens ‘Limelight’ leaves is discussed. Optimization of the main parameters that affect the extraction process was carried out. More specifically, the composition of the solvent (ethanol, water, and mixtures of the two at a 25% v/v step gradient) and the main PEF-related parameters (i.e., pulse duration, pulse period, and electric field intensity) was optimized. The obtained extracts were examined for their polyphenol content with the Folin–Ciocalteu assay and individual polyphenols were also assessed with high-performance liquid chromatography. The extracts obtained with PEF were compared to the extract compared without PEF, in terms of total polyphenols. According to the results, the optimum extraction parameters were found to be a pulse duration of 10 μs, a pulse period of 1000 μs, and an electric field intensity of 0.85 kV cm−1 after 20 min of extraction. The optimum solvent was found to be the 50% (v/v) ethanol/water mixture. The extract prepared under the optimum conditions was found to contain 58% more polyphenols compared with the extract prepared without PEF. Moreover, an increase of up to 92% was recorded for specific polyphenols. Based on the above, it was evidenced that the examined parameters influenced the recovery of polyphenols, suggesting that such parameters should be also examined in similar studies, in order to maximize the extraction yield of polyphenols.","PeriodicalId":74387,"journal":{"name":"Oxygen (Basel, Switzerland)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45653883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Throop, Durwash Badr, M. Durka, M. Bukač, Rana Zakerzadeh
Determination of abdominal aortic aneurysm (AAA) rupture risk involves the accurate prediction of mechanical stresses acting on the arterial tissue, as well as the wall strength which has a correlation with oxygen supply within the aneurysmal wall. Our laboratory has previously reported the significance of an intraluminal thrombus (ILT) presence and morphology on localized oxygen deprivation by assuming a uniform consistency of ILT. The aim of this work is to investigate the effects of ILT structural composition on oxygen flow by adopting a multilayered porous framework and comparing a two-layer ILT model with one-layer models. Three-dimensional idealized and patient-specific AAA geometries are generated. Numerical simulations of coupled fluid flow and oxygen transport between blood, arterial wall, and ILT are performed, and spatial variations of oxygen concentrations within the AAA are obtained. A parametric study is conducted, and ILT permeability and oxygen diffusivity parameters are individually varied within a physiological range. A gradient of permeability is also defined to represent the heterogenous structure of ILT. Results for oxygen measures as well as filtration velocities are obtained, and it is found that the presence of any ILT reduces and redistributes the concentrations in the aortic wall markedly. Moreover, it is found that the integration of a porous ILT significantly affects the oxygen transport in AAA and the concentrations are linked to ILT’s permeability values. Regardless of the ILT stratification, maximum variation in wall oxygen concentrations is higher in models with lower permeability, while the concentrations are not sensitive to the value of the diffusion coefficient. Based on the observations, we infer that average one-layer parameters for ILT material characteristics can be used to reasonably estimate the wall oxygen concentrations in aneurysm models.
{"title":"Analyzing the Effects of Multi-Layered Porous Intraluminal Thrombus on Oxygen Flow in Abdominal Aortic Aneurysms","authors":"A. Throop, Durwash Badr, M. Durka, M. Bukač, Rana Zakerzadeh","doi":"10.3390/oxygen2040034","DOIUrl":"https://doi.org/10.3390/oxygen2040034","url":null,"abstract":"Determination of abdominal aortic aneurysm (AAA) rupture risk involves the accurate prediction of mechanical stresses acting on the arterial tissue, as well as the wall strength which has a correlation with oxygen supply within the aneurysmal wall. Our laboratory has previously reported the significance of an intraluminal thrombus (ILT) presence and morphology on localized oxygen deprivation by assuming a uniform consistency of ILT. The aim of this work is to investigate the effects of ILT structural composition on oxygen flow by adopting a multilayered porous framework and comparing a two-layer ILT model with one-layer models. Three-dimensional idealized and patient-specific AAA geometries are generated. Numerical simulations of coupled fluid flow and oxygen transport between blood, arterial wall, and ILT are performed, and spatial variations of oxygen concentrations within the AAA are obtained. A parametric study is conducted, and ILT permeability and oxygen diffusivity parameters are individually varied within a physiological range. A gradient of permeability is also defined to represent the heterogenous structure of ILT. Results for oxygen measures as well as filtration velocities are obtained, and it is found that the presence of any ILT reduces and redistributes the concentrations in the aortic wall markedly. Moreover, it is found that the integration of a porous ILT significantly affects the oxygen transport in AAA and the concentrations are linked to ILT’s permeability values. Regardless of the ILT stratification, maximum variation in wall oxygen concentrations is higher in models with lower permeability, while the concentrations are not sensitive to the value of the diffusion coefficient. Based on the observations, we infer that average one-layer parameters for ILT material characteristics can be used to reasonably estimate the wall oxygen concentrations in aneurysm models.","PeriodicalId":74387,"journal":{"name":"Oxygen (Basel, Switzerland)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41825753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Haematoccocus lacustris (previously H. pluvialis) is a desiccation-tolerant unicellular freshwater green alga. During acclimation to desiccation, astaxanthin-rich lipid bodies and low-molecular-weight antioxidants (α-tocopherol, glutathione) accumulate, while the chloroplast area and chlorophyll contents decrease, which may facilitate desiccation tolerance by preventing damage mediated by reactive oxygen species (ROS). Here, we investigated the influence of moisture, light, oxygen, and temperature on redox homeostasis and cell longevity. Respiration and unbound freezable water were detectable in cells equilibrated to ≥90% relative humidity (RH), a threshold above which viability considerably shortened. At 92.5% RH and 21 °C, antioxidants depleted over days as cells lost viability, especially in an oxygen-rich atmosphere, supporting the role of ROS production in uncoupled respiration in viability loss. At 80% RH and 21 °C, redox homeostasis was maintained over weeks, and longevity was less influenced by oxygen. Light and oxygen was a lethal combination at 92.5% RH, under which pigments bleached, while in the dark only astaxanthin bleached. Viability positively correlated with glutathione concentrations across all treatments, while correlation with α-tocopherol was weaker, indicating limited viability loss from lipid peroxidation at 80% RH. In cells equilibrated to 50% RH, longevity and redox homeostasis showed strong temperature dependency, and viability was maintained at sub-zero temperatures for up to three years, revealing cryogenic storage to be an optimal strategy to store H. lacustris germplasm.
{"title":"Humidity and Light Modulate Oxygen-Induced Viability Loss in Dehydrated Haematococcus lacustris Cells","authors":"T. Roach, Alessandro Fambri, D. Ballesteros","doi":"10.3390/oxygen2040033","DOIUrl":"https://doi.org/10.3390/oxygen2040033","url":null,"abstract":"Haematoccocus lacustris (previously H. pluvialis) is a desiccation-tolerant unicellular freshwater green alga. During acclimation to desiccation, astaxanthin-rich lipid bodies and low-molecular-weight antioxidants (α-tocopherol, glutathione) accumulate, while the chloroplast area and chlorophyll contents decrease, which may facilitate desiccation tolerance by preventing damage mediated by reactive oxygen species (ROS). Here, we investigated the influence of moisture, light, oxygen, and temperature on redox homeostasis and cell longevity. Respiration and unbound freezable water were detectable in cells equilibrated to ≥90% relative humidity (RH), a threshold above which viability considerably shortened. At 92.5% RH and 21 °C, antioxidants depleted over days as cells lost viability, especially in an oxygen-rich atmosphere, supporting the role of ROS production in uncoupled respiration in viability loss. At 80% RH and 21 °C, redox homeostasis was maintained over weeks, and longevity was less influenced by oxygen. Light and oxygen was a lethal combination at 92.5% RH, under which pigments bleached, while in the dark only astaxanthin bleached. Viability positively correlated with glutathione concentrations across all treatments, while correlation with α-tocopherol was weaker, indicating limited viability loss from lipid peroxidation at 80% RH. In cells equilibrated to 50% RH, longevity and redox homeostasis showed strong temperature dependency, and viability was maintained at sub-zero temperatures for up to three years, revealing cryogenic storage to be an optimal strategy to store H. lacustris germplasm.","PeriodicalId":74387,"journal":{"name":"Oxygen (Basel, Switzerland)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48725196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The emergence of complexity requires cooperation, yet selection typically favors defectors that do not cooperate. Such evolutionary conflict can be alleviated by a variety of mechanisms, allowing complexity to emerge. Chemiosmosis is one such mechanism. In syntrophic relationships, the chemiosmotic partner benefits simply from exporting products. Failure to do this can result in highly reduced electron carriers and detrimental amounts of reactive oxygen species. Nevertheless, the role of this mechanism in the history of life (e.g., the origin of eukaryotes from prokaryotes) seems questionable because of much lower atmospheric levels of oxygen and a largely anaerobic ocean. In this context, the role of sulfur should be considered. The last eukaryotic common ancestor (LECA) was a facultative aerobe. Under anaerobic conditions, LECA likely carried out various forms of anaerobic metabolism. For instance, malate dismutation, in which malate is both oxidized and reduced, allows re-oxidizing NADH. The terminal electron acceptor, fumarate, forms succinate when reduced. When oxygen is present, an excess of succinate can lead to reverse electron flow, forming high levels of reactive oxygen species. Under anaerobic conditions, reactive sulfur species may have formed. Eliminating end products may thus have had a selective advantage even under the low atmospheric oxygen levels of the Proterozoic eon.
{"title":"Reactive Oxygen and Sulfur Species: Partners in Crime","authors":"N. Blackstone","doi":"10.3390/oxygen2040032","DOIUrl":"https://doi.org/10.3390/oxygen2040032","url":null,"abstract":"The emergence of complexity requires cooperation, yet selection typically favors defectors that do not cooperate. Such evolutionary conflict can be alleviated by a variety of mechanisms, allowing complexity to emerge. Chemiosmosis is one such mechanism. In syntrophic relationships, the chemiosmotic partner benefits simply from exporting products. Failure to do this can result in highly reduced electron carriers and detrimental amounts of reactive oxygen species. Nevertheless, the role of this mechanism in the history of life (e.g., the origin of eukaryotes from prokaryotes) seems questionable because of much lower atmospheric levels of oxygen and a largely anaerobic ocean. In this context, the role of sulfur should be considered. The last eukaryotic common ancestor (LECA) was a facultative aerobe. Under anaerobic conditions, LECA likely carried out various forms of anaerobic metabolism. For instance, malate dismutation, in which malate is both oxidized and reduced, allows re-oxidizing NADH. The terminal electron acceptor, fumarate, forms succinate when reduced. When oxygen is present, an excess of succinate can lead to reverse electron flow, forming high levels of reactive oxygen species. Under anaerobic conditions, reactive sulfur species may have formed. Eliminating end products may thus have had a selective advantage even under the low atmospheric oxygen levels of the Proterozoic eon.","PeriodicalId":74387,"journal":{"name":"Oxygen (Basel, Switzerland)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49506085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ridwan P. Putra, I. B. Rachman, H. Horino, I. Rzeznicka
Nickel oxyhydroxides (NiOOHs) are well-known for their superior activity toward oxygen evolution reaction (OER) in alkaline solutions. However, their activity toward oxygen reduction reaction (ORR) has been largely unexplored. There exist three NiOOH polymorphs: α-, β-, and γ-NiOOH, characterized by different interlayer spacing. Although still debated, γ-NiOOH with a large layer spacing has been indicated as the active phase for OER. Here, a highly crystalline γ-NiOOH was prepared in a carbon matrix by the in situ electrochemical transformation of nickel dithiooxamide Ni(dto) in 1 M KOH solution. The catalyst prepared in this way showed low overpotential not only for OER, but also for ORR in alkaline solutions. The onset potential for ORR is ~0.81 V vs. RHE, and the reaction proceeds via the 2e− transfer pathway. The high OER catalytic activity and relatively low ORR overpotential make this nanocomposite catalyst a good candidate for bifunctional OER/ORR catalyst, stable in alkaline solutions.
{"title":"Bifunctional Catalytic Activity of γ-NiOOH toward Oxygen Reduction and Oxygen Evolution Reactions in Alkaline Solutions","authors":"Ridwan P. Putra, I. B. Rachman, H. Horino, I. Rzeznicka","doi":"10.3390/oxygen2040031","DOIUrl":"https://doi.org/10.3390/oxygen2040031","url":null,"abstract":"Nickel oxyhydroxides (NiOOHs) are well-known for their superior activity toward oxygen evolution reaction (OER) in alkaline solutions. However, their activity toward oxygen reduction reaction (ORR) has been largely unexplored. There exist three NiOOH polymorphs: α-, β-, and γ-NiOOH, characterized by different interlayer spacing. Although still debated, γ-NiOOH with a large layer spacing has been indicated as the active phase for OER. Here, a highly crystalline γ-NiOOH was prepared in a carbon matrix by the in situ electrochemical transformation of nickel dithiooxamide Ni(dto) in 1 M KOH solution. The catalyst prepared in this way showed low overpotential not only for OER, but also for ORR in alkaline solutions. The onset potential for ORR is ~0.81 V vs. RHE, and the reaction proceeds via the 2e− transfer pathway. The high OER catalytic activity and relatively low ORR overpotential make this nanocomposite catalyst a good candidate for bifunctional OER/ORR catalyst, stable in alkaline solutions.","PeriodicalId":74387,"journal":{"name":"Oxygen (Basel, Switzerland)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42442149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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