Indicators Of Redox Status Research Articles

Effects of a Curcumin/Silymarin/Yeast-Based Mycotoxin Detoxifier on Redox Status and Growth Performance of Weaned Piglets under Field Conditions.

The aim of this in vivo study was to investigate the effects of a novel mycotoxin detoxifier whose formulation includes clay (bentonite and sepiolite), phytogenic feed additives (curcumin and silymarin) and postbiotics (yeast products) on the health, performance and redox status of weaned piglets under the dietary challenge of fumonisins (FUMs). The study was conducted in duplicate in the course of two independent trials on two different farms. One hundred and fifty (150) weaned piglets per trial farm were allocated into two separate groups: (a) T1 (control group): 75 weaned piglets received FUM-contaminated feed and (b) T2 (experimental group): 75 weaned piglets received FUM-contaminated feed with the mycotoxin-detoxifying agent from the day of weaning (28 days) until 70 days of age. Thiobarbituric acid reactive substances (TBARSs), protein carbonyls (CARBs) and the overall antioxidant capacity (TAC) were assessed in plasma as indicators of redox status at 45 and 70 days of age. Furthermore, mortality and performance parameters were recorded at 28, 45 and 70 days of age, while histopathological examination was performed at the end of the trial period (day 70). The results of the present study reveal the beneficial effects of supplementing a novel mycotoxin detoxifier in the diets of weaners, including improved redox status, potential hepatoprotective properties and enhanced growth performance.

Unbalanced redox status network as an early pathological even in congenital cataracts

Aims/Purpose: The lens proteome undergoes dramatic composition changes during development and maturation. Defective developmental processes lead to congenital cataracts that account for about 30% of cases of childhood blindness. Gene mutations are associated with approximately 50% of early‐onset forms of lens opacity, with the remainder being of unknown aetiology. To gain a better understanding of congenital cataractogenesis, we utilized a transgenic mouse model expressing a mutant ubiquitin protein in the lens (K6W‐Ub) that recapitulates many of the early pathological changes seen in human congenital cataracts.Methods: We performed MS‐based tandem‐mass‐tag quantitative proteomics (TMT), computational molecular phenotyping (CMP), high‐performance liquid chromatography (HPLC), western blotting and immunohistochemical analysis in E15, P1 and P30 control or K6W‐Ub lenses.Results: TMT identified proteins that were altered during normal lens differentiation, some of which were also altered in cataractous lenses. These included proteins in glutathione and amino acid metabolic pathways. CMP revealed that glutathione and taurine were reduced spatially altered in the K6W‐Ub cataractous lens. HPLC revealed that both the ratio GSH/GSSG and taurine, two indicators of redox status, were differentially compromised in K6W‐Ub cataractous lenses.Conclusions: Our findings shed light on the molecular mechanisms associated with congenital cataracts and point out that unbalanced redox status due to reduced levels of taurine and glutathione, metabolites already linked to age‐related cataract, could be a major underlying mechanism behind lens opacities that appear early in life.Funding: Funding was provided by grants RYC 2018‐024434‐I, MINECO PID 2020‐119466RB‐I00, FUSP‐PPC‐19‐B53C4C64, NIH RO1EY026979 (to AT), USDA 8050‐51000‐089‐01S (to AT).

Supplementation with Jatobá-do-cerrado flour (Hymenaea stigonocarpa Mart.) decreases hypothalamic inflammation and improves obesity parameters in rats on a high-fat diet

To evaluate the impact of jatobá-do-cerrado flour on nutritional, inflammatory, and oxidative stress markers, an study was conducted using male Wistar rats. These animals were allocated into four groups: a standard diet (Control), a high-fat diet (HFD), a diet with jatobá-do-cerrado flour (JCF), and a combination of high-fat diet and jatobá-do-cerrado flour (HFD + JCF). Comprehensive evaluations included food intake, cytokine concentrations, and redox status indicators. HFD group exhibited increased caloric intake and fat mass, elevated circulating IL-6, and heightened lipid peroxidation markers. This group also showed increased hypothalamic concentrations of IL-6, TNFα, and lipid peroxidation. In contrast, the HFD + JCF group showed reduced caloric intake, fat mass, and improvements in redox balance and inflammatory markers both in the blood and hypothalamus. SummaryIn the current study, we evaluated the potential of Jatobá-do-cerrado flour in mitigating the effects of a high-fat diet in adult Wistar rats. The addition of fat to the animals' diet for 63 days induced obesity, dyslipidemia, as well as an increase in inflammatory and lipid peroxidation markers, both in the blood and hypothalamus. Conversely, supplementation with Jatobá-do-Cerrado flour showed anti-obesogenic effects and these may be associated with the reduction of inflammation and oxidative stress. Therefore, supplementation with this flour has the potential to be a functional food for the treatment or prevention of obesity.

Serum pro-inflammatory biomarkers associated with improvement in quality of life in pulmonary tuberculosis.

Pulmonary dysfunction is an underestimated complication in tuberculosis (TB) infection, affecting quality of life (QoL). Although respiratory function tests objectively reflect lung disturbances in a specific moment, predictors of illness severity at the time of diagnosis are still lacking. We measured serum pro-inflammatory cytokines (TNF-α and IL-8), eicosanoids (PGE2, LTB4, RvD1, Mar1, and LXA4), a marker of tissue damage (cell-free nucleosomes), and indicators of redox status (malonaldehyde, 8-isoprostane, total oxidants, and antioxidants), as well as a score of radiological abnormalities (SRA) and a QoL questionnaire, in 25 patients with pulmonary TB at the time of diagnosis (t0) and two months after the initiation of treatment (t2). We found higher antioxidant levels in the patients with the worst QoL at t0, and all the indicators of the prooxidant state were significantly reduced at t2, while the total antioxidant levels increased. LTB4, a pro-inflammatory eicosanoid, was diminished at t2, while all the pro-resolutory lipids decreased substantially. Significant correlations between the SRA and the QoL scores were observed, the latter showing a substantial reduction at t2, ranking it as a reliable tool for monitoring disease evolution during TB treatment. These results suggest that evaluating a combination of these markers might be a valuable predictor of QoL improvement and a treatment response indicator; in particular, the oxidation metabolites and eicosanoid ratios could also be proposed as a future target for adjuvant therapies to reduce inflammation-associated lung injury in TB disease.

Unbalanced redox status network as an early pathological event in congenital cataracts

The lens proteome undergoes dramatic composition changes during development and maturation. A defective developmental process leads to congenital cataracts that account for about 30% of cases of childhood blindness. Gene mutations are associated with approximately 50% of early-onset forms of lens opacity, with the remainder being of unknown etiology. To gain a better understanding of cataractogenesis, we utilized a transgenic mouse model expressing a mutant ubiquitin protein in the lens (K6W-Ub) that recapitulates most of the early pathological changes seen in human congenital cataracts. We performed mass spectrometry-based tandem-mass-tag quantitative proteomics in E15, P1, and P30 control or K6W-Ub lenses. Our analysis identified targets that are required for early normal differentiation steps and altered in cataractous lenses, particularly metabolic pathways involving glutathione and amino acids. Computational molecular phenotyping revealed that glutathione and taurine were spatially altered in the K6W-Ub cataractous lens. High-performance liquid chromatography revealed that both taurine and the ratio of reduced glutathione to oxidized glutathione, two indicators of redox status, were differentially compromised in lens biology. In sum, our research documents that dynamic proteome changes in a mouse model of congenital cataracts impact redox biology in lens. Our findings shed light on the molecular mechanisms associated with congenital cataracts and point out that unbalanced redox status due to reduced levels of taurine and glutathione, metabolites already linked to age-related cataract, could be a major underlying mechanism behind lens opacities that appear early in life.

Effects of a Dietary Multi-Strain Probiotic and Vaccination with a Live Anticoccidial Vaccine on Growth Performance and Haematological, Biochemical and Redox Status Indicators of Broiler Chickens.

A total of 256 male Ross 308 chickens were assigned to four treatments in a 2 × 2 factorial design with two levels of the anticoccidial vaccine (ACV) Livacox T (none or 1 × dose) with or without dietary supplementation with the probiotic Protexin® (P). The growth performance parameters for the test periods (1-21, 22-42, and 1-42 d) and oocyst per gram (OPG) at weekly intervals were analysed. Blood samples were collected at 16 post-vaccination (pv) days to measure selected haematological, biochemical, redox, and immunological parameters. ACV administration worsened the performance parameters of the chickens for 1-21 d pv, while supplementation with P reduced this negative effect with a significant improvement in 1-21 d body weight gain and feed conversion ratio. ACV administration increased % phagocytic cells (%PC), phagocytic index (PI), respiratory burst activity, proportion of monocytes, and activities of aspartate aminotransferase (AST) and lactate dehydrogenase, while it decreased the catalase activity and concentration of malondialdehyde and peroxides. The dietary administration of P significantly increased counts of red blood cells and white blood cells and increased %PC and PI, while it decreased the heterophil proportion, heterophil/lymphocyte ratio (p = 0.059), and alanine aminotransferase and AST activities. The oocyst counts were comparable in all sampling periods, except on 14 d pv, as supplementation with P significantly decreased 14 d OPG, thus indicating a positive influence of P on immunity development. In conclusion, dietary supplementation with P led to improved performance, better immunity, and benefits in health status in broilers vaccinated with the ACV, without interfering with the circulating vaccine strains.

The Level of Indicators of Redox Status in Muscles of Fish from Lakes with Different Trophy

The Level of Indicators of Redox Status in Muscles of Fish from Lakes with Different Trophy

Oxidative stress assessment and its relationship with the prevalence of atherogenic risk in patients with type 2 diabetes.

During diabetes, prolonged hyperglycemia is characterized by the generation of free radicals via multiple mechanisms leading to various diabetic complications including cardiovascular diseases. This study aims to determine the relationship between a deregulation of the oxidative state in type 2 diabetes patients and the prevalence of atheroma plate formation. This research was carried out at the Bouguerra Boulaares hospital and Alia Salah hospital in Tebessa, Algeria, on 560 patients with type 2 diabetes (300 women and 260 men), compared with 100 normal subjects (50 women and 50 men). For all subjects the following parameters were estimated: blood pressure, BMI (body mass index), glucose, glycated hemoglobin, total cholesterol, HDL Cholesterol, LDL Cholesterol, Triglycerides, Creatinine, serum redox status indicators (GSH, GPx, GSTs, and MDA) and a complete blood count was performed. The findings of this study indicated a slight increase in arterial pressure in 336 diabetic patients (60%) with an HbA1c level between 7 and 9% (210 patients) and > 9% (126 patients); while the flow of the glomerular filtration remained within the norms for all the studied subjects. Patients showed an increase in blood glucose levels, disturbance of the lipid parameters with an increase in lipid peroxidation and a decrease in serum and erythrocyte antioxidant defense. It can be concluded that the formation of atheroma plate in diabetics is caused by the oxidation of circulating lipoproteins by free radicals generated following hyperglycemia, which can be avoided by supplementing antioxidant molecules such as antioxidant vitamins, trace elements.

Comparative Analysis of Atherosclerosis Risk Factors in the Staff of the Tbilisi (Georgia) Cleaning Service

Objective Search of pathogenetic mechanisms and risk factors of atherosclerosis in the employees of the cleaning service in Tbilisi. Materials and Methods As a result of a preliminary survey and examination of 200 employes of Tbilisi cleaning service aged 25-45 years (2014-2016), 22 patients with angina, hypercholesterolemia, intimae-media thickness > 0.65 mm, were selected into I group, and 23 individuals without these disorders into II group. In the blood plasma of the selected patients the intensity of oxidative metabolism parameters, TAA and MDA were determined. The variance and correlation analysis (АNOVA) was used for conducting the comparative analysis of the levels of studied parameters. Results In the combined group (I+II) there are several reliable correlations between the Age -TCol, Age-MDA, BMI-Tg, BMI-MDA, LDLChol-HDLChol, LDLChol–TChol, HDLChol-TChol, LDLChol-MDA, LDLChol-TAA. no correlation between these parameters in individual groups (I and II) was found. That indicates that we have an imaginary correlation related to the large intergroup difference between the average values of the group indicators, that is the values of various indicators change during the development of the pathological process, but there is no causal relationship between these alterations. The reliable TAA-MDA correlation in the combined group (I+II) is related to the high anticorrelation between these parameters and the significantly higher average value of TAA in the low-risk group (II) in comparison to the high-risk group (I). Conclusion The results analysis indicates both the diagnostic value of redox status indicators and their leading role in the atherogenesis processes. In populations with a high risk of atherosclerosis, monitoring of serum TAA is recommended.

Effect of sheep’s genotype and grazing site on haematological and redox status indicators

The aim of the study was to determine the effect of sheep’s genotype and grazing site on their hematological and redox status indicators. The experiment was carried out on sheep of the Świniarka and Uhruska breeds grazed in naturally valuable areas (xerothermic grasslands) and kept in a sheepfold. Several blood indices were determined by ABACUS Junior Vet, including the numbers of leukocytes, thrombocytes and erythrocytes, hemoglobin and procalcitonin concentrations, hematocrit, the mean red cell volume and the average hemoglobin concentration in red blood cells, the percentages of lymphocytes, monocytes and granulocytes, the degree of erythrocyte anisocytosis and the degree of variation in platelet volume. The concentrations of lipid peroxides and malonic dialdehyde, the activity of superoxide dismutase and catalase and total antioxidant potential were determined by spectrophotometric methods. The study showed that Świniarka sheep had a greater antioxidant potential and higher white blood cell counts than Uhrusian sheep. It was found that sheep’s grazing place had a significant influence on the antioxidant status and hematological indicators of their blood. An improvement in antioxidant potential and hematological blood parameters was achieved in sheep grazed in naturally valuable areas, that is, in the Stawska Góra nature reserve and on xerothermic grasslands in Gródek and Kąty, compared to sheep fed in a sheepfold

Effect of sheep’s genotype and grazing site on haematological and redox status indicators

The aim of the study was to determine the effect of sheep’s genotype and grazing site on their hematological and redox status indicators. The experiment was carried out on sheep of the Świniarka and Uhruska breeds grazed in naturally valuable areas (xerothermic grasslands) and kept in a sheepfold. Several blood indices were determined by ABACUS Junior Vet, including the numbers of leukocytes, thrombocytes and erythrocytes, hemoglobin and procalcitonin concentrations, hematocrit, the mean red cell volume and the average hemoglobin concentration in red blood cells, the percentages of lymphocytes, monocytes and granulocytes, the degree of erythrocyte anisocytosis and the degree of variation in platelet volume. The concentrations of lipid peroxides and malonic dialdehyde, the activity of superoxide dismutase and catalase and total antioxidant potential were determined by spectrophotometric methods. The study showed that Świniarka sheep had a greater antioxidant potential and higher white blood cell counts than Uhrusian sheep. It was found that sheep’s grazing place had a significant influence on the antioxidant status and hematological indicators of their blood. An improvement in antioxidant potential and hematological blood parameters was achieved in sheep grazed in naturally valuable areas, that is, in the Stawska Góra nature reserve and on xerothermic grasslands in Gródek and Kąty, compared to sheep fed in a sheepfold.

Dynamic Resistance Training Promotes Better Neuromuscular Benefits And Reduces Oxidative Stress In Healthy Wistar Rats

PURPOSE: Resistance training (RT) is used as a non-pharmacological tool in the prevention and treatment of various diseases. However, few studies have evaluated the different neuromuscular adaptations promoted by dynamic (DRT) and isometric (IRT), and their impact on redox status.This study aimed to compare the different adaptations on muscle strength and oxidative stress in healthy Wistar male rats. METHODS: Fifteen male Wistar rats at 12 weeks of age were randomized into 3 groups: control group (CTL; n = 5), DRT (n = 5) and IRT (n = 5). All animals were adapted for 2 weeks on the vertical ladder. After the animals were submitted to dynamic strength muscle (DSM) (test performed every 15 days) and maximum isometric resistance (MIR) (pre and post-training) tests. Both DRT and IRT were performed 5 times a week on non-consecutive days for 12 weeks, with a duration of ~ 22 min per session, consisting of 1 set of 8 uninterrupted climbs for 1 min, with a 30% overload of DSM. The animals of the IRT group remained in isometry for 1 minute. The level of significance was set at P<0.05. RESULTS: The DRT group presented a greater gain of the DSM (390±86 and 686±66 g, pre and post-training, P<0.05) compared to the groups CTL (339±65 and 427±39 g, pre and post-training, P<0.05) and IRT (369±31 and 393±41 g, pre and post-training, P<0.05). The DRT (6.9±3.4 and 24.7±5.3 min, pre and post-training) and IRT (9.6±4.6 and 39.1±15.9 min, pre and post-training) groups showed the same gain in MIR (P>0.05). The DRT group presented reduction of lipid peroxidation (17±4 and 9±3 μM, pre and post-training, P<0.05) (TBARS), with increased bioavailability of nitric oxide (NO) (122±28 and 177±14 μM, pre and post-training, P<0.05) and total antioxidant capacity (627±32 and 715±45 μM, pre and post-training, P<0.05) (TAC). These redox status indicators did not change between CTL; TBARS (15±5 and 17±7 μM, pre and post- training), NO (118±15 and 125±32 μM, pre and post-training) and TAC (636±29 and 660±10 μM, pre and post-training) and IRT; TBARS (16±3 and 15±3 μM, pre and post- training), NO (126±18 and 133±14 μM, pre and post-training) and TAC (631±8 and 647±20 μM, pre and post-training) groups (P>0.05). CONCLUSIONS: These results suggest that DRT promotes better neuromuscular benefits with improved oxidative stress in healthy Wistar male rats.

Redox status on different regions of the central nervous system of obese and lean rats treated with green tea extract

Objectives: The purpose of this study was to evaluate some indicators of redox status, and inflammation on different regions of the central nervous system (CNS) of obese rats treated with green tea (GT). We hypothesized that obesity could affect the redox balance in different brain regions due to the diverse nature of the cells as well as the selective neuronal vulnerability to oxidative stress, and GT could triggers benefits effects restoring the redox status.Methods: Male Wistar rats were treated with GT by gavage (12 weeks/5 days/week; 500 mg/kg of body weight) and obesity was induced by cafeteria diet (8 weeks). After this period, the animals were killed and brain tissue (cerebral cortex, cerebellum, and brainstem) was removed to evaluate oxidative stress and inflammation (cytokine release).Results: We showed that the cafeteria diet had little effect on redox balance in the cerebral cortex and cerebellum; however, the brainstem was the region of the CNS most sensitive to cafeteria diet-induced redox unbalance. GFAP expression was increased in the cerebral cortex of obese rats and reduced by GT. It was also evident that GT treatment had numerous beneficial effects against oxidative damage to biomolecules in all brain regions analyzed.Discussion: Our study established that different CNS regions show selective neuronal vulnerability when exposed to a diet enriched with fats and sugars, and the beneficial effect of GT was similar among these regions. We conclude that GT could be a good strategy for improving and maintaining brain function under healthy and pathological conditions.

Influence of the manner of use, age and sex on the biochemical and antioxidant blood parameters of Malopolski horses

The aim of the study was to determine whether the manner of use, age and sex affect selected biochemical and antioxidant blood parameters of Malopolski horses, and whether there is an interaction between these factors. The study was conducted on 30 riding horses of the Malopolski breed divided by sex (18 mares and 12 colts) and age (2-6 years, 7-9 years and 10-16 years). The horses were also divided according to usage (recreational use and sports use). The research was conducted at the end of March and the beginning of April during two consecutive years. In each year, blood from the same horses was analysed. Blood plasma was analyzed for total protein, glucose, bilirubin, urea, uric acid, creatinine, Zn+2, Cu+2 and Fe+2. In addition the activities of superoxide dismutase, catalase, plasma total antioxidant status (FRAP) and the concentration of malondialdehyde were determined. Neither the age of the horses nor their use (for recreation or sport) had significant effect on biochemical indices of blood. However, the CAT activity and the levels of MDA, zinc and iron were higher in the blood of horses used for sports than they were in the blood of horses used for recreation. Age affected the value of the biomarkers of redox status. Compared with young horses, older animals showed increased oxidative processes (an increase in MDA) and a reduced antioxidant defense (SOD, FRAP, Cu+2, Zn+2). The sex of the horses had a significant influence on the levels of both biochemical and antioxidant parameters. Colts had significantly higher contents of TP, UA, SOD, CAT, Cu+2 and Fe+2 and lower of BIL and MDA compared to mares. The interaction observed in this study between age or sex and usage on the antioxidant parameters confirms that the redox status indicators can be helpful in assessing the welfare of Malopolski horses undergoing differentiated exertion.

Redox status in the blood of ewes in the perinatal period and during lactation

Abstract The aim of the study was to determine the effect of the perinatal period on redox status indicators in the blood of ewes before and after lambing and during lactation. The study was performed on 12 ewes of the synthetic SCP line. Blood for testing of redox parameters was collected seven times: before pregnancy, 1.5 months and 24 h before lambing, 2 and 24 h after lambing, and in the fourth and eighth weeks of lactation. The following blood indices were determined by spectrophotometry: lipid peroxides, malondialdehyde, superoxide dismutase, catalase, plasma total antioxidant capacity, uric acid, urea, bilirubin, and creatinine. The tests showed that during the perinatal period reactions are generated which lead to oxidative stress. Oxidative stress in pregnant ewes was found to increase during the period before lambing and may persist even up to weeks 4-8 of lactation.

Maternal Oxidant and Antioxidant Status in the Third Trimester of Gestation and its Relation to the Birthweight

The aim of this study was to determine if the behavior of redox status indicators and their relation to birthweight, previously reported, was dependent only on the period between 30 and 36 weeks gestation, or if it was a characteristic of the third trimester. The present study was done in pregnant women between 25 and 29 and between 30 and 36 weeks of gestation; in addition, a reference group with non-pregnant women was formed. Ferric reducing potential, uric acid, albumin, vitamins C, E, A, erythrocyte reduced glutathione concentrations, total extracellular superoxide dismutase and catalase activity were measured as antioxidant indicators, and serum malondialdehyde plus 4-hydroxynonenal concentration as a lipoperoxidation indicator. No significant differences between the values of the indicators of redox status between the two groups of pregnant women were found. Significantly lower maternal serum Ferric Reducing Potential and albumin concentration were noted in pregnant women between 25 to 29 and 30 to 36 weeks, respectively. However, extracellular superoxide dismutase activity and erythrocyte reduced glutathione concentration were increased in gestational groups compared to nonpregnant group. Malondialdehyde concentrations plus 4-hydroxy-nonenal correlated significantly and inversely with birthweight, while erythrocyte reduced glutathione correlated significantly and directly in the two groups of pregnant women; however, the activity of the total extracellular superoxide dismutase correlated with birthweight only in the group of pregnant women between 30 and 36 weeks. We conclude that the behavior of the indicators of maternal redox status and its influence on birthweight is similar for both groups of pregnant women with gestational age studied.

Dietary supplementation with cysteine prodrugs selectively restores tissue glutathione levels and redox status in protein-malnourished mice

Protein malnutrition (PM) is a major health problem in the world. PM compromises antioxidant defense in the body. In particular, PM decreases tissue glutathione (GSH) levels. A high protein diet was found to restore tissue GSH levels in animal studies, however it is not recommended for the early phase of PM rehabilitation. Therefore, using dietary supplementation to restore tissue GSH without giving a high protein diet may be an adjunct therapy that helps improve antioxidant status during the early rehabilitation of PM. In this study, we systematically compared the efficacy of dietary supplementation of four cysteine prodrugs: N-acetylcysteine, L-2-oxo-4-thiazolidine-carboxylate, methionine, and GSH, on tissue GSH in mice fed a protein-deficient (0.5%) diet. Results showed that dietary supplementation of cysteine prodrugs to PM mice restored GSH levels in liver, lung, heart and spleen, but not in colon. GSH and GSSG levels in brain and kidney were not affected by cysteine prodrug or PM. Supplementation also restored the redox status in liver and heart (based on GSH/GSSG), and in liver and spleen (based on GSSG/2GSH reduction potential). This suggests that the restoration of GSH levels and redox status by cysteine prodrugs are tissue-specific, and that the two indicators of redox status are not always interchangeable. However, all four prodrugs exhibited similar GSH-enhancing capacities, showing no prodrug-specificity as seen in cell culture studies. In conclusion, this study provided information that may be useful in a clinical setting where a short-term oral supplementation of cysteine prodrugs is necessary for the early rehabilitation of PM patients.

Tansley Review No. 112

The gradual but huge increase in atmospheric O2 concentration that followed the evolution of oxygenic photosynthesis is one consequence that marks this event as one of the most significant in the earth's history. The high redox potential of the O2/water couple makes it an extremely powerful electron sink that enables energy to be transduced in respiration. In addition to the tetravalent interconversion of O2 and water, there exist a plethora of reactions that involve the partial reduction of O2 or photodynamic energy transfer to produce active oxygen species (AOS). All these redox reactions have become integrated during evolution into the aerobic photosynthetic cell. This review considers photosynthesis as a whole‐cell process, in which O2 and AOS are involved in reactions at both photosystems, enzyme regulation in the chloroplast stroma, photorespiration, and mitochondrial electron transport in the light. In addition, oxidants and antioxidants are discussed as metabolic indicators of redox status, acting as sensors and signal molecules leading to acclimatory responses. Our aim throughout is to assess the insights gained from the application of mutagenesis and transformation techniques to studies of the role of O2 and related redox components in the integrated regulation of photosynthesis. contents I. Introduction 360 II. Photoinhibition and active oxygen 360 III. Oxygen as an electron acceptor 362 IV. Redox regulation of photosynthetic metabolism 368 V. Photorespiration 369 VI. Respiration 376 VII. Photosynthesis and redox signal transduction 378 VIII. Conclusions 380 Acknowledgements 381