Non-enzymatic Antioxidant Responses Research Articles

Evaluation of phytotoxicity, biochemical profiles, bioaccumulation hazard, and toxicity implications of battery manufacturing industrial discharge using a soilless cultivation system

This study has been devoted to the compositional evaluation of battery manufacturing industrial discharge (ID) and comprehensive assessment of: (i) plant vigor, chlorophylls contents, oxidative stress biomarkers; (ii) antioxidant defense system; (iii) non-enzymatic antioxidant responses; (iv) bioaccumulative profiles of toxic pollutants; and (v) in vitro genotoxicity and cytotoxicity of the four weeks ID-irrigated Ipomoea aquatica. Pb was identified as the dominating pollutant (5.35 mg/L) in the ID, with the accumulative profiles ranging from 0.002 to 1.36 mg/kg dry weight, in the descending order of root > shoot > leaf within Ipomoea aquatica. Profound inhibition of roots (26.60%) and shoots growth (20.53%), reduction of chlorophylls contents (39.81%), excessive-generation of superoxide anion (53.33%), hydrogen peroxide (55%), and lipid peroxidation (26.15%) were recorded. Antioxidant enzymes were up-regulated while the ferric reducing antioxidant power and radicals scavenging activities were concurrently enhanced. The in vitro toxicity of ID was verified by the significant dose-dependent increase in the mitochondrial respiratory inhibition associated-cell death and DNA destruction in the HepG2 cell (p < 0.05). These acquired findings have signified the threatening implications of Pb-contaminated ID-assisted irrigation on the sustainability of environmental and public health, and food security management.

Antioxidants responses of two halophytes under aluminium stress alone or combined with salt

Al stress is a serious environmental problem that affects plant physiology and biochemical processes and reduces productivity in the agricultural sector. This study is a comparative study between the antioxidant responses of two different halophyte species and focuses on two halophytes Arthrocnemum indicum and Tamarix gallica. Both halophytes species exposed to different concentrations of Al (200, 500, 800) µM alone or combined with NaCl (200 mM) and the effect of Al on oxidative damage and enzymatic and non-enzymatic antioxidant responses were determined. Our results demonstrated that Tamarix gallica was more tolerant to Al stress than Arthrocnemum indicum and this by a low level of MDA registered. In addition, T. gallica showed more marked antioxidant activities. However, salinity improves the tolerance of A. indicum by increased levels of glycine betaine and proline. Nevertheless, T. gallica is still more tolerant according to the tolerance index than A. indicum and this species is a favorable plant material to soils phytoremediation. T. gallica can be successfully used for phytostabilization of Al-contaminated saline soils

Non-Enzymatic and Enzymatic Antioxidant Responses of Hypericum perforatum L. Hairy Roots upon Photooxidative Stress

The aim of this study was to evaluate the non-enzymatic and enzymatic antioxidant response of fifteen Hypericum perforatum L. dark-grown (HR1 A-HR1 O) and photoperiod-exposed (HR2 A-HR2 O) hairy root clones. Dark-grown HR1 clones were characterized with high biomass accumulation and up-regulated phenylpropanoid metabolism through phenylalanine ammonia lyase (PAL)-mediated production of flavonoids, flavan-3-ols and anthocyanins. These groups of phenolics showed superior hydrogen-donating capability and significantly contributed to the antioxidant capacity of dark-grown HR1 clones. Photoperiod-exposed HR2 clones showed green coloration with shoot regenerative potential and reduced biomass accumulation. Photoperiod exposition improved the production of hypericins, as well as ferrous chelating properties and lipid peroxidation inhibition activity in HR2 cultures. Furthermore, HR2 clones were represented with enhanced activity of antioxidant enzymes (guaiacol peroxidase, catalase and superoxide dismutase) that resulted in suppression of oxidative stress markers (hydrogen peroxide, superoxide anion and malondialdehyde). These observations revealed the involvement of an efficient antioxidant defense system in the adaptive response of HR to photooxidative stress. Altogether, photoperiod-exposed H. perforatum HR2 clones were considered as a promising alternative for further scale-up production of naphthodianthrones that could be used in the pharmaceutical industry.

Role of Polyamines in the Response to Salt Stress of Tomato.

Plants irrigated with saline solutions undergo osmotic and oxidative stresses, which affect their growth, photosynthetic activity and yield. Therefore, the use of saline water for irrigation, in addition to the increasing soil salinity, is one of the major threats to crop productivity worldwide. Plant tolerance to stressful conditions can be improved using different strategies, i.e., seed priming and acclimation, which elicit morphological and biochemical responses to overcome stress. In this work, we evaluated the combined effect of priming and acclimation on salt stress response of a tomato cultivar (Solanum lycopersicum L.), very sensitive to salinity. Chemical priming of seeds was performed by treating seeds with polyamines (PAs): 2.5 mM putrescine (PUT), 2.5 mM spermine (SPM) and 2.5 mM spermidine (SPD). Germinated seeds of primed and non-primed (controls) were sown in non-saline soil. The acclimation consisted of irrigating the seedlings for 2 weeks with tap water, followed by irrigation with saline and non-saline water for 4 weeks. At the end of the growth period, morphological, physiological and biochemical parameters were determined. The positive effects of combined treatments were evident, when primed plants were compared to non-primed, grown under the same conditions. Priming with PAs improved tolerance to salt stress, reduced the negative effects of salinity on growth, improved membrane integrity, and increased photosynthetic pigments, proline and enzymatic and non-enzymatic antioxidant responses in all salt-exposed plants. These results may open new perspectives and strategies to increase tolerance to salt stress in sensitive species, such as tomato.

Enzymatic and Non-Enzymatic Antioxidant Responses of Young Tomato Plants (cv. Micro-Tom) to Single and Combined Mild Nitrogen and Water Deficit: Not the Sum of the Parts

This study aims to perform a broad analysis of the antioxidant (AOX) responses of young tomato plants exposed to single and combined mild nitrogen (N) and water deficits through the evaluation of oxidative biomarkers, non-enzymatic and enzymatic AOX components. 'Micro-Tom' seedlings were subjected to four treatments: control (CTR; 100%N + 100%W), N deficit (N; 50%N), water deficit (W; 50%W), and combined deficits (N + W; 50%N + 50%W). An enhancement of several non-enzymatic and enzymatic components was found in plants subjected to N + W deficit, which presented higher anthocyanins accumulation (up to 103%) as well as higher levels of superoxide dismutase (SOD) transcripts at root level and of ascorbate peroxidase (APX) and catalase (CAT) transcripts at shoot level. This increase in the gene expression was also translated in augmented SOD (up to 202%), APX (up to 155%) and CAT (up to 108%) activity compared to CTR plants and the single deficits. Overall, tomato plants were able to employ defense strategies to cope with this combined deficit, as demonstrated by the higher total AOX capacity (up to 87%) compared to the single deficits, which contributed to the maintenance of their redox homeostasis, with unchanged values of lipid peroxidation and hydrogen peroxide compared with CTR plants.

Bacterioplankton Associated with Toxic Cyanobacteria Promote Pisum sativum (Pea) Growth and Nutritional Value through Positive Interactions.

Research on Plant Growth-Promoting Bacteria (PGPB) has focused much more on rhizospheric bacteria. However, PGPB associated with toxic cyanobacterial bloom (TCB) could enter the rhizosphere through irrigation water, helping plants such as Pisum sativum L. (pea) overcome oxidative stress induced by microcystin (MC) and improve plant growth and nutritional value. This study aimed to isolate bacteria associated with toxic cyanobacteria, test PGPB properties, and inoculate them as a consortium to pea seedlings irrigated with MC to investigate their role in plant protection as well as in improving growth and nutritional value. Two bacterioplankton isolates and one rhizosphere isolate were isolated and purified on a mineral salt medium supplemented with 1000 μg/L MC and identified via their 16S rRNA gene. The mixed strains were inoculated to pea seedlings in pots irrigated with 0, 50, and 100 μg/L MC. We measured the morphological and physiological parameters of pea plants at maturity and evaluated the efficiency of the plant’s enzymatic and non-enzymatic antioxidant responses to assess the role and contribution of PGPB. Both bacterioplankton isolates were identified as Starkeya sp., and the rhizobacterium was identified as Brevundimonas aurantiaca. MC addition significantly (p < 0.05) reduced all the growth parameters of the pea, i.e., total chlorophyll content, leaf quantum yield, stomatal conductance, carotenoids, and polyphenol contents, in an MC concentration-dependent manner, while bacterial presence positively affected all the measured parameters. In the MC treatment, the levels of the pea’s antioxidant traits, including SOD, CAT, POD, PPO, GST, and ascorbic acid, were increased in the sterile pots. In contrast, these levels were reduced with double and triple PGPB addition. Additionally, nutritional values such as sugars, proteins, and minerals (Ca and K) in pea fruits were reduced under MC exposure but increased with PGPB addition. Overall, in the presence of MC, PGPB seem to positively interact with pea plants and thus may constitute a natural alternative for soil fertilization when irrigated with cyanotoxin-contaminated water, increasing the yield and nutritional value of crops.

Response of antioxidant defences of Microcystis aeruginosa (Cyanobacteria) to increased temperature

ABSTRACT Cyanobacteria have different defence mechanisms, which have improved over time, to avoid or mitigate oxidative stress by using antioxidants as reactive species scavengers. The objective of the present study was to evaluate the effects of increased temperature, over several days of exposure, on biomass, lipid damage, oxygen and nitrogen reactive species, and different antioxidants on Microcystis aeruginosa (harmful cyanobacteria). Unicellular cultures were exposed to elevated (29°C) and control (26°C) temperatures for 10 d. The temperature shift induced activation of enzymatic antioxidant system and changes in content of non-enzymatic antioxidants after 2 d of exposure to 29°C. This was responsible for a lower content of reactive species during the subsequent days. An increase in enzymatic antioxidant activity, depending on the exposure time, was observed. In addition, there was a differential non-enzymatic antioxidant response that was also time dependent, which could be important to counteract oxidative stress induced by increases in temperature. Overall, the initial increase in β carotene and astaxanthin content followed by an increased activity of catalase together with superoxide dismutase and glutathione S transferase activities allowed the cyanobacteria to counteract the oxidative stress induced, and improved their growth at the increased temperature. Our results increase the understanding of different antioxidant responses, integrating enzymatic and non-enzymatic protection mechanisms over time when exposing M. aeruginosa to heatwaves. The survival capacity of Cyanobacteria in drinking water supplies can have serious implications for the environment and human health.

A new cyanobacterial species with a protective effect on lettuce grown under salinity stress: Envisaging sustainable agriculture practices

In this work, a new terrestrial cyanobacterial species, Oculatella lusitanica LEGE 161147, was isolated and characterized using a polyphasic approach. Morphologically, O. lusitanica shares characteristics with different Oculatella species (mainly with O. crustae-formantes), lacking distinctive features. However, the phylogeny based on the 16S rRNA gene sequence and the 16S-23S ITS secondary structures support the establishment of this isolate as a new species. O. lusitanica is placed within a clade mainly composed by other Oculatella terrestrial strains; however, it forms a separate lineage. In addition, our species differs from the other Oculatella described so far by lacking the V2 helix within the ITS region. Since cyanobacteria are known to release compounds that promote plant growth and/or increase their tolerance to stresses, the effect of this newly described cyanobacterial species on Lactuca sativa (lettuce) plants development and salinity stress resistance was evaluated. Our results showed that, although the cyanobacterium had no impact on plant growth under the conditions tested, it was able to mitigate the deleterious salinity stress effects on plant size, root and aerial part fresh weight, by eliciting the non-enzymatic antioxidant response system (proline, H2O2 and reduced glutathione). In addition, the microorganism was able to induce a priming effect on lettuce plants by stimulating defensive mechanisms under non-stress conditions, and enhances the activity of nitrogen metabolism-related enzymes glutamate dehydrogenase, glutamine synthetase and nitrate reductase. These results indicate that this native terrestrial cyanobacterial species could be employed as a tool in sustainable agricultural practices.

Western Dietary Pattern Antioxidant Intakes and Oxidative Stress: Importance During the SARS-CoV-2/COVID-19 Pandemic

ABSTRACTThe importance of balanced dietary habits, which include appropriate amounts of antioxidants to maintain the immune system, has become increasingly relevant during the current SARS-CoV-2/COVID-19 pandemic, because viral infections are characterized by high oxidative stress. Furthermore, the measures taken by governments to control the pandemic have led to increased anxiety, stress, and depression, which affect physical and mental health, all of which are influenced by nutritional status, diet, and lifestyle. The Mediterranean diet (MD), Atlantic diet (AD), and the Dietary Guidelines for Americans all provide the essential vitamins, minerals, and phenolic compounds needed to activate enzymatic and nonenzymatic antioxidant responses. However, viral pandemics such as the current COVID-19 crisis entail high oxidative damage caused by both the infection and the resultant social stresses within populations, which increases the probability and severity of infection. Balanced dietary patterns such as the MD and the AD are characterized by the consumption of fruit, vegetables, legumes, olive oil, and whole grains with low intakes of processed foods and red meat. For a healthy lifestyle in young adults, the MD in particular provides the required amount of antioxidants per day for vitamins D (0.3–3.8 μg), E (17.0 mg), C (137.2–269.8 mg), A (1273.3 μg), B-12 (1.5–2.0 μg), and folate (455.1–561.3 μg), the minerals Se (120.0 μg), Zn (11.0 mg), Fe (15.0–18.8 mg), and Mn (5.2–12.5 mg), and polyphenols (1171.00 mg) needed to maintain an active immune response. However, all of these diets are deficient in the recommended amount of vitamin D (20 μg/d). Therefore, vulnerable populations such as elders and obese individuals could benefit from antioxidant supplementation to improve their antioxidant response. Although evidence remains scarce, there is some indication that a healthy diet, along with supplemental antioxidant intake, is beneficial to COVID-19 patients.

Morpho‐physiological traits associated with drought responses in soybean

AbstractDrought is currently a major constraint to soybean [Glycine max (L.) Merr.] production worldwide and is becoming more widespread due to increased aridity and warmer temperatures in the context of global climate change. In this context, breeding for soybean varieties more tolerant to drought stress is critical and requires efficient screening techniques. To find traits associated with drought tolerance at the vegetative stage that are still present at the reproductive stage, we evaluated morphological, physiological, and biochemical traits in two soybean genotypes contrasting in their response to drought stress. Under drought stress at the vegetative stage, the tolerant A 5009 RG genotype showed higher proline and chlorophyll contents, and early activation of the enzymatic antioxidant system compared with well‐watered plants. On the other hand, the sensitive ADM 50048 genotype increased malondialdehyde (oxidative damage marker) and nonenzymatic antioxidant response under stress. Manipulative field assays under contrasting levels of water availability at the reproductive stage mimicked the biochemical patterns observed in the greenhouse tests for the sensitive and tolerant genotypes. A principal component analysis of parameters from vegetative and reproductive stages revealed proline and chlorophyll contents as drought tolerance traits in soybean. We found those traits useful to classify 14 genotypes from the Instituto Nacional de Tecnologia Agropecuaria (INTA) germplasm bank, identifying two new drought‐tolerant genotypes (PI 548510 and PI 200492). We propose proline and chlorophylls as useful tools to classify soybean genotypes according to their drought responses in early developmental stages, potentially reducing breeding times.

Consequences of oxidative damage on the fatty acid profile in muscle of Cichlasoma amazonarum acutely exposed to copper.

Rapid industrialization results in the production of large quantities of waste that are commonly discharged into water bodies, leading to the damage of the aquatic ecosystem and freshwater organisms. Copper (Cu) can induce oxidative damage in fish muscle, the main fish portion that is consumed by humans. However, the responses of the Amazon fish Cichlasoma amazonarum and its capacity to withstand acute Cu concentrations found in Amazon water around mines remain unknown. Thus, the aim of this study was to evaluate whether exposure to Cu causes muscle oxidative stress and/or oxidative damage and impairs the fillet fatty acid profile of C. amazonarum acutely exposed to Cu found in Amazon waters around mines. Muscle reactive oxygen species and protein carbonylation levels were significantly higher in fish exposed to 1500μg/L Cu compared with the control group, while muscle lipid peroxidation levels were significantly higher in fish exposed to 500, 750, and 1500μg/L Cu compared with control group. Muscle antioxidant capacity against peroxyl radical's levels and glutathione peroxidase activity were significantly lower in fish exposed to 1500μg/L Cu compared with the control group, while muscle superoxide dismutase activity was significantly lower in fish exposed to 750 and 1500μg/L Cu compared with control group. The total content of saturated fatty acids was significantly higher in fish exposed to 1500μg/L Cu compared with the control group, while the total content of monounsaturated fatty acids and sum of n3 fatty acids were significantly lower in fish exposed to 1500μg/L Cu compared with control group. No significant difference was observed regarding muscle catalase, glutathione S-transferase, and glutathione reductase activities. Based on these lines of evidence, the results of this comprehensive study agree with the initial hypothesis that the exposure to Cu found in Amazon water around mines induces oxidative damage and inhibits enzymatic and non-enzymatic antioxidant response in the muscle of C. amazonarum exposed to high Cu levels. Moreover, the impairment of the fillet fatty acid profile appears to be mediated by oxidative damage, representing a negative impact on fish health.

Non-enzymatic antioxidant responses of Mytilus galloprovincialis: Insights into the physiological role against metal-induced oxidative stress

The exposure to metals is known to generate oxidative stress in living organisms, which can result in the induction of protective antioxidant defences, both enzymatic and non-enzymatic. This work aims to obtain new data on the existing links among several non-enzymatic components of the antioxidant system, that are physiologically related to both metal sequestration and defense against metal-induced oxidative stress, using the blue mussels (Mytilus galloprovincialis) as a model organism. Specimens of this marine bivalve were experimentally exposed to cadmium (Cd), used as oxidative stress inducer. Cd, metallothionein (MT), glutathione (GSH), malondialdehyde (MDA) contents, and glutathione reductase (GR) activity in gills and in digestive glands were assessed at 0, 12, 24, 48, 72 and 96 h. The obtained results provide new data about the relationships among the non-enzymatic antioxidant cellular components considered in this study. These constitute the prompt physiological responses to the oxidative stress in blue mussels exposed to Cd in controlled laboratory conditions.

Dietary ochratoxin A (OTA) decreases growth performance and impairs muscle antioxidant system and meat fatty acid profiles in juvenile tambaqui (Colossoma macropomum)

Plant-based ingredients are successfully replacing fishmeal in fish feeds. However, this practice increases the risk of feed contamination by mycotoxins that reduce production and heath associated with oxidative damage. The aim of this study was to determine whether feed contaminated with environmentally relevant concentrations of ochratoxin A (OTA) causes muscle oxidative damage in tambaqui (Colossoma macropomum), and to determine whether this feed impairs fatty acid profiles in fish meat. Final mean weight, weight gain, daily weight gain, feed efficiency, and specific growth rate were significantly lower in fish fed 1.6 and 2.4 mg OTA/kg compared to those fed basal diet, while feed conversion was significantly higher in these same groups compared to the basal group. Levels of reactive oxygen species and lipid peroxidation in muscle were significantly higher in fish fed 1.6 and 2.4 mg OTA/kg compared to those in the basal group. Likewise, muscle superoxide dismutase and glutathione peroxidase activities were significantly higher in fish fed 1.6 and 2.4 mg OTA/kg then in those fed basal feed. The total content of saturated fatty acids was significantly higher, and total content of polyunsaturated fatty acids was significantly lower in fish fed 2.4 mg OTA/kg compared to those fed basal feed. Taken together, the data suggest that OTA-contaminated feed induces oxidative damage and disturbs enzymatic and non-enzymatic antioxidant responses in tambaqui meat. The perturbations of fatty acid profiles in fish meat appears to mediated by oxidative damage, representing negative impact on fish health and presenting concerns for consumers of fish.

Photoperiod and elicitors increase steviol glycosides, phenolics, and flavonoid contents in root cultures of Stevia rebaudiana

The establishment of green root cultures of Stevia rebaudiana Bertoni, and the effect of elicitors such as hydrogen peroxide (H2O2) and methyl jasmonate (MeJA), is shown in the present study. Stevioside, rebaudioside A, and the isomers steviol/isosteviol were identified through DFI-ESI-IT-MSn and UPLC-TOFMS spectrometric systems, in combination with solid-phase extraction. The accumulation of steviol glycosides increased by 2.4 times (compared to the control value of 22.35 μgSG per gDW), with the addition of 250 μM H2O2. The non-enzymatic antioxidant response, which resulted from production of phenolic and flavonoid compounds, was modified based on the elicitor and the dose used. The maximum accumulation of flavonoids was induced on the third day with the addition of H2O2 (250 or 500 μM), and with MeJA (250 or 500 μM); the increase was observed on the fifth day. The enzymatic antioxidant response of the catalase and peroxidase from the roots under elicitation confirmed the stress conditions.

Biochemical and molecular approach of oxidative damage triggered by water stress and rewatering in sunflower seedlings of two inbred lines with different ability to tolerate water stress.

Water stress accelerates the generation of reactive oxygen species, which trigger a cascade of antioxidative defence mechanisms comprising enzymatic and nonenzymatic antioxidants. The aim of this study was to investigate the oxidative damage and the antioxidative defence systems in seedlings of the water stress-tolerant (B71) and the sensitive (B59) inbred lines of sunflower (Helianthus annuus L.) in response to water stress and rewatering. In addition, we characterised the transcriptomic profile associated with enzymatic antioxidative defence. An elevated electrolyte leakage in B59 indicated increased plasmatic membrane permeability, which correlated with greater sensitivity to water stress. In response to water stress, both lines showed an increase in malondialdehyde and H2O2 content but these increases were more noticeable in the sensitive line. In both lines, an increase in enzymatic activity (e.g. peroxidase and ascorbate peroxidase) was not sufficient to overcome the H2O2 accumulation triggered by water stress. Upon water stress, the overall expression level of genes associated with the enzymatic antioxidant system increased in B71 and decreased in B59, which showed downregulated levels of most genes in the shoots. The general profile of phenolic compounds was clearly different between organs and between inbred lines. The B59 line activated nonenzymatic antioxidant responses to counteract the oxidative stress caused by water stress. The tolerance of B71 to water stress could be associated with compensatory antioxidant mechanisms based on the expression of genes encoding enzyme components of the ascorbate-glutathione and redoxin cycles, which contributed to explaining, at least partly, the response of this line.

Enzymes and non-enzymatic antioxidants responses to sequential cold stress in polymorphic noble scallop Chlamys nobilis with different total carotenoids content

Noble scallop, an economically important edible marine bivalve displays polymorphism in shells (golden and brown) and flesh colors (orange and white). Mass mortality of noble scallops usually occurs during the winter months. Interestingly, carotenoid-rich golden scallops demonstrated much higher survival rates than brown scallops in winter. In order to understand the response of polymorphic noble scallops to sequential cold stress, the present study aimed to investigate the enzyme and non-enzymatic antioxidant responses of golden and brown scallops under sequential cold stress. Parameters evaluated included total carotenoid content (TCC), fatty acid composition, total antioxidant capacity (TAC), methylenedioxyamphetamine (MDA) content, catalase (CAT) activity, and superoxide dismutase (SOD) enzyme activity. The results of the present study revealed that golden scallops have higher cold tolerance than brown scallops. Golden and brown scallops are well adapted to low water temperature of above 12 °C, but in areas where winter water temperatures are below 12 °C, golden scallops are more suitable for aquaculture than brown scallops. The findings of this study are crucial to understanding the physiological responses of polymorphic scallops to cold stress and identify suitable candidates for winter aquaculture.

Chronic exposure of Oreochromis niloticus to sub-lethal copper concentrations: Effects on growth, antioxidant, non-enzymatic antioxidant, oxidative stress and non-specific immune responses

BackgroundTrace elements of copper (Cu) are one of the main forms of ecological noxious waste in freshwater systems that affect the survival and development of organisms. The objective of the current study was to investigate the effects of chronic exposure to Cu on the growth, oxidative stress, immune and biochemical response in the Nile tilapia, Oreochromis niloticus. MethodsThree groups of O. niloticus were tested as follows; the first group was used as the control (not treated with Cu in water), while the 2nd and 3rd groups were exposed to (low) 40 μg L−1 and (high) 400 μg L−1 concentrations of Cu added to water, respectively. The duration of the experiment, which was conducted in triplicate, was 60 d. End points were evaluated on days 30 and 60. Following 30 d and 60 d of exposure to Cu, the fish were removed from experimental tanks to determine growth. Consequently, blood samples were collected from caudal veins at the end of the trial period (30 d and 60 d) and serum was separated to evaluate different immunological parameters, such as lysozymes (LYZ), respiratory burst activity (RBA) and myeloperoxidase (MPO). Gill and liver tissues were collected for evaluation of Cu and certain biochemical parameters as follows: antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST); non-enzymatic antioxidants such as glutathione (GSH) and metallothionein (MT), and oxidative stress indicators such as malondialdehyde (MDA) and protein carbonyl (PCO). The results pertaining to treatments and the control were compared using two-way ANOVA and Tukey’s HSD test. The level of significance was set at P ≤ 0.05. Data were expressed as mean ± SD. ResultsChronic exposure to Cu did not induce any mortality in fish during the test period. However, following exposure to Cu, growth of fish in the exposed groups was affected more than that in the control group (unexposed to Cu). In addition, accumulation of Cu in the liver tissue was higher than that in the gill tissues of fish exposed to Cu, compared to that in the control. Gill and liver tissues of Cu-exposed fish showed a significant (P ≤ 0.05) reduction in the activities of the antioxidant enzymes, SOD, CAT, GPx, and GST, compared to those of unexposed fish. Non-enzymatic antioxidants, GSH and MT, in gill and liver tissues were significantly increased (P ≤ 0.05) in fish exposed to both concentrations of Cu, compared to those in unexposed fish. Oxidative stress indicators, MDA and PCO in gills and liver of Cu-exposed fish was significantly (P ≤ 0.05) at both tested concentrations, when compared to control group. Non-specific immune response of LYZ, RBA, and MPO activity in serum decreased significantly (P ≤ 0.05) in Cu-exposed fish, compared with that of unexposed fish. ConclusionOverall, the present results highlighted that chronic exposure to Cu ions may exert a strong effect on the antioxidant and immune responses of O. niloticus. Changes in antioxidant enzymes, oxidative stress effects and immune parameters during post-chronic metal exposure may indicate the potential of these parameters as biomarkers of metal toxicity in aquatic ecosystems.

Joint effects of Si and mycorrhiza on the antioxidant metabolism of two pigeonpea genotypes under As (III) and (V) stress.

Arsenic (As) is the most hazardous soil contaminant, which inactivates metabolic enzymes and restrains plant growth. To withstand As stress conditions, use of some alleviative tools, such as arbuscular mycorrhizal (AM) fungi and silicon (Si), has gained importance. Therefore, the present study evaluated comparative and interactive effects of Si and arbuscular mycorrhiza-Rhizophagus irregularis on phytotoxicity of arsenate (As V) and arsenite (As III) on plant growth, ROS generation, and antioxidant defense responses in pigeonpea genotypes (Tolerant-Pusa 2002; Sensitive-Pusa 991). Roots of As III treated plants accumulated significantly higher total As than As V supplemented plants, more in Pusa 991 than Pusa 2002, which corresponded to proportionately decreased plant growth, root to biomass ratio, and oxidative burst. Although Si nutrition and AM inoculations improved plant growth by significantly reducing As uptake and the resultant oxidative burst, AM was relatively more efficient in upregulating enzymatic and non-enzymatic antioxidant defense responses as well as ascorbate-glutathione pathway when compared with Si. Pusa 2002 was more receptive to Si nourishment due to its ability to establish more efficient mycorrhizal symbiosis, which led to higher Si uptake and lower As concentrations. Moreover, +Si+AM bestowed better metalloid resistance by further reducing ROS and strengthening antioxidants. Results demonstrated that the genotype with more efficient AM symbiosis in As-contaminated soils could accrue higher benefits of Si fertilization in terms of metalloid tolerance in pigeonpea.

TRF1 as a major contributor for telomeres' shortening in the context of obesity

Obesity is a prevalent multifactorial chronic disorder characterized by metabolic dysregulation. Sustained pro-oxidative mediators trigger harmful consequences that reflect at systemic level and contribute for the establishment of a premature senescent phenotype associated with macromolecular damage (DNA, protein, and lipids). Telomeres are structures that protect chromosome ends and are associated with a six-protein complex called the shelterin complex and subject to regulation. Under pro-oxidant conditions, telomere attrition and the altered expression of the shelterin proteins are central for the establishment of many pathophysiological conditions such as obesity. Thus, considering that individuals with obesity display a systemic oxidative stress profile that may compromise the telomeres length or its regulation, the aim of this study was to investigate telomere homeostasis in patients with obesity and explore broad/systemic associations with the expression of shelterin genes and the plasma redox state. We performed a cross-sectional study in 39 patients with obesity and 27 eutrophic subjects. Telomere length (T/S ratio) and gene expression of shelterin components were performed in peripheral blood mononuclear cells by qPCR. The oxidative damage (lipid peroxidation and protein carbonylation) and non-enzymatic antioxidant system (total radical-trapping antioxidant potential/reactivity, sulfhydryl and GSH content) were evaluated in plasma. Our results demonstrate that independently of comorbidities, individuals with obesity had significantly shorter telomeres, augmented expression of negative regulators of the shelterin complex, increased lipid peroxidation and higher oxidized protein levels associated with increased non-enzymatic antioxidant defenses. Principal component analysis revealed TRF1 as a major contributor for firstly telomeres shortening. In conclusion, our study is first showing a comprehensive analysis of telomeres in the context of obesity, associated with dysregulation of the shelterin components that was partially explained by TRF1 upregulation that could not be reversed by the observed adaptive non-enzymatic antioxidant response.

Modulation of Oxidative Status by Normoxia and Hypoxia on Cultures of Human Dermal Fibroblasts: How Does It Affect Cell Aging?

Reactive oxygen species (ROS) production in the skin is among the highest compared to other organs, and a clear correlation exists between ROS production and skin aging. Many attempts are underway to reduce oxidative stress in the skin by topical treatment or supplementation with antioxidants/cosmeceuticals, and cultures of human dermal fibroblasts (HDF) are widely used for these studies. Here, we examined the influence of oxygen tension on cell aging in HDF and how this impacted ROS production, the enzymatic and nonenzymatic antioxidant response system, and the efficacy of this defense system in limiting DNA damage and in modulating gene expression of proteins involved in the extracellular matrix, linked to skin aging. We investigated a selection of parameters that represent and reflect the behavior of cellular responses to aging and oxygen tension. Serial passaging of HDF under normoxia (21%) and hypoxia (5%) leads to cell aging as confirmed by β-galactosidase activity, p16 expression, and proliferation rate. However, in HDF under 21% O2, markers of aging were significantly increased compared to those under 5% O2 at matched cell passages despite having lower levels of intracellular ROS and higher levels of CoQ10, total GSH, SOD1, SOD3, and mitochondrial superoxide anion. miRNA-181a, which is known to be upregulated in HDF senescence, was also analyzed, and indeed, its expression was significantly increased in old cells at 21% O2 compared to those at 5% O2. Upregulation of MMP1 and downregulation of COL1A1 along with increased DNA damage were also observed under 21% O2 vs 5% O2. The data highlight that chronic exposure to atmospheric 21% O2 is able to trigger hormetic adaptive responses in HDF that however fail, in the long term, to prevent cellular aging. This information could be useful in further investigating molecular mechanisms involved in adaptation of skin fibroblasts to oxidative stress and may provide useful hints in addressing antiaging strategies.