Molecular and structural antioxidant defenses against oxidative stress in animals

KC. Heat exposure limits pentose phosphate pathway activity in bumblebees

Bumblebee populations across the globe are experiencing substantial declines due to climate change, with major consequences for pollination services in both natural and agricultural settings. Using an economically important species, Bombus impatiens, we explored the physiological mechanisms that may cause susceptibility to extreme heat events. We tested the hypothesis that heat exposure limits the activity of the pentose phosphate pathway (PPP)-a parallel pathway to glycolysis that can use nectar sugar to generate antioxidant potential and combat oxidative stress. Using isotopically labelled glucose, we tracked PPP activity in B. impatiens at rest, during exercise and during a post-exercise recovery period under two different temperature regimes (22°C and 32°C). We found that the PPP is routinely used by B. impatiens at moderate temperatures, but that its activity is markedly reduced when ATP demands are high, such as during periods of exercise and heat exposure. We also exposed B. impatiens to either 22°C or 32°C for 5 hours and assessed levels of oxidative damage (lipid peroxidation, protein carbonyls) and antioxidant potential [reduced (GSH) and oxidized (GSSG) glutathione concentrations]. Interestingly, bees exhibited little oxidative damage after the thermal exposure, but we found a lower GSH:GSSG ratio in 32°C-exposed bees, reflecting lower antioxidant potential. Overall, our study demonstrates that acute heat stress severely limits PPP activity and may constrain antioxidant potential in B. impatiens. The repeated attenuation of this pathway in a warming climate may have more severe physiological consequences for this species, with potential implications for pollination services across North America.

Harmony in Motion: Unraveling the Nexus of Sports, Plant-Based Nutrition, and Antioxidants for Peak Performance

The intricate interplay between plant-based nutrition, antioxidants, and their impact on athletic performance forms the cornerstone of this comprehensive review. Emphasizing the pivotal importance of dietary choices in the realm of sports, this paper sets the stage for an in-depth exploration of how stress and physical performance are interconnected through the lens of nutrition. The increasing interest among athletes in plant-based diets presents an opportunity with benefits for health, performance, and recovery. It is essential to investigate the connection between sports, plants, and antioxidants. Highlighting the impact of nutrition on recovery and well-being, this review emphasizes how antioxidants can help mitigate oxidative stress. Furthermore, it discusses the growing popularity of plant-based diets among athletes. It elaborates on the importance of antioxidants in combating radicals addressing stress levels while promoting cellular health. By identifying rich foods, it emphasizes the role of a balanced diet in ensuring sufficient intake of these beneficial compounds. Examining stress within the context of sports activities, this review provides insights into its mechanisms and its impact on athletic performance as well as recovery processes. This study explores the impact of plant-based diets on athletes including their types, potential advantages and challenges. It also addresses the drawbacks of relying on plant-based diets, concerns related to antioxidant supplementation and identifies areas where further research is needed. Furthermore, the review suggests directions for research and potential innovations in sports nutrition. Ultimately it brings together the aspects of sports, plant-based nutrition, and antioxidants to provide a perspective for athletes, researchers and practitioners. By consolidating existing knowledge, it offers insights that can pave the way for advancements in the ever-evolving field of sports nutrition.

Genotype-environment associations reveal genes potentially linked to avian malaria infection in populations of an endemic island bird

Patterns of pathogen prevalence are, at least partially, the result of coevolutionary host-pathogen interactions. Thus, exploring the distribution of host genetic variation in relation to infection by a pathogen within and across populations can provide important insights into mechanisms of host defence and adaptation. Here, we use a landscape genomics approach (Bayenv) in conjunction with genome-wide data (ddRADseq) to test for associations between avian malaria (Plasmodium) prevalence and host genetic variation across 13 populations of the island endemic Berthelot's pipit (Anthus berthelotii). Considerable and consistent spatial heterogeneity in malaria prevalence was observed among populations over a period of 15 years. The prevalence of malaria infection was also strongly positively correlated with pox (Avipoxvirus) prevalence. Multiple host loci showed significant associations with malaria prevalence after controlling for genome-wide neutral genetic structure. These sites were located near to or within genes linked to metabolism, stress response, transcriptional regulation, complement activity and the inflammatory response, many previously implicated in vertebrate responses to malarial infection. Our findings identify diverse genes - not just limited to the immune system - that may be involved in host protection against malaria and suggest that spatially variable pathogen pressure may be an important evolutionary driver of genetic divergence among wild animal populations, such as Berthelot's pipit. Furthermore, our data indicate that spatio-temporal variation in multiple different pathogens (e.g. malaria and pox in this case) may have to be studied together to develop a more holistic understanding of host pathogen-mediated evolution.

Chlorothalonil as a potential endocrine disruptor in male zebrafish (Danio rerio): Impact on the hypothalamus-pituitary-gonad axis and sperm quality

Chlorothalonil is a broad-spectrum organochlorine fungicide widely employed in agriculture to control fungal foliar diseases. This fungicide enters aquatic environments through the leaching process, leading to toxicity in non-target organisms. Organic contaminants can impact organism reproduction as they have the potential to interact with the neuroendocrine system. Although there are reports of toxic effects of chlorothalonil, information regarding its impact on reproduction is limited. The aim of the present study was to evaluate the influence of chlorothalonil on male reproductive physiology using the zebrafish (Danio rerio) as ecotoxicological model. Zebrafish were exposed for 7 days to two concentrations of chlorothalonil (0.1 and 10 μg/L) along with a control group (with DMSO - 0.001%). Gene expression of hypothalamus-pituitary-gonad axis components (gnrh2, gnrh3, lhr, fshr, star, hsd17b1, hsd17b3, and cyp19a1), as well as hepatic vitellogenin concentration were assessed. In sperm cells, reactive oxygen species (ROS) content, lipid peroxidation (LPO), mitochondrial functionality, and membrane integrity and fluidity were evaluated. Results indicate that exposure to the higher concentration of chlorothalonil led to a reduction in brain gnr2 expression. In gonads, mRNA levels of lhr, star, and hsd17b1 were decreased at both chlorothalonil concentrations tested. Similarly, hepatic vitellogenin concentration was reduced. Regarding sperm cells, a decreased ROS level was observed, without significant difference in LPO level. Additionally, a higher mitochondrial potential and lower membrane fluidity were observed in zebrafish exposed to chlorothalonil. These findings demonstrate that chlorothalonil acts as an endocrine disruptor, influencing reproductive control mechanisms, as evidenced by changes in expression of genes HPG axis, as well as hepatic vitellogenin concentration. Furthermore, our findings reveal that exposure to this contaminant may compromise the reproductive success of the species, as it affected sperm quality parameters.

Songbirds avoid the oxidative stress costs of high blood glucose levels: a comparative study

Chronically high blood glucose levels (hyperglycaemia) can compromise healthy ageing and lifespan at the individual level. Elevated oxidative stress can play a central role in hyperglycaemia-induced pathologies. Nevertheless, the lifespan of birds shows no species-level association with blood glucose. This suggests that the potential pathologies of high blood glucose levels can be avoided by adaptations in oxidative physiology at the macroevolutionary scale. However, this hypothesis remains unexplored. Here, we examined this hypothesis using comparative analyses controlled for phylogeny, allometry and fecundity based on data from 51 songbird species (681 individuals with blood glucose data and 1021 individuals with oxidative state data). We measured blood glucose at baseline and after stress stimulus and computed glucose stress reactivity as the magnitude of change between the two time points. We also measured three parameters of non-enzymatic antioxidants (uric acid, total antioxidants and glutathione) and a marker of oxidative lipid damage (malondialdehyde). We found no clear evidence for blood glucose concentration being correlated with either antioxidant or lipid damage levels at the macroevolutionary scale, as opposed to the hypothesis postulating that high blood glucose levels entail oxidative costs. The only exception was the moderate evidence for species with a stronger stress-induced increase in blood glucose concentration evolving moderately lower investment into antioxidant defence (uric acid and glutathione). Neither baseline nor stress-induced glucose levels were associated with oxidative physiology. Our findings support the hypothesis that birds evolved adaptations preventing the (glyc)oxidative costs of high blood glucose observed at the within-species level. Such adaptations may explain the decoupled evolution of glycaemia and lifespan in birds and possibly the paradoxical combination of long lifespan and high blood glucose levels relative to mammals.

Efficacy of creatine nitrate supplementation on redox status and mitochondrial function in pectoralis major muscle of preslaughter transported broilers

This study was purposed to investigate the efficacy of dietary creatine nitrate (CrN) supplementation on redox status and mitochondrial function in pectoralis major (PM) muscle of broilers that experienced preslaughter transport. A total of 288 Arbor Acres broilers (28-day-old) were randomly assigned into five dietary treatments, including a basal diet or the basal diet supplemented with 600 mg/kg guanidinoacetic acid (GAA), 300, 600, or 900 mg/kg CrN for 14 days, respectively. On the transportation day, the basal diet group was divided into two groups on average, resulting in six groups. The control group was transported for 0.5 h and the other groups for 3 h (identified as Control, T3h, GAA600, CrN300, CrN600, and CrN900 group, respectively), and all crates were randomly placed on the truck travelling at an average speed of 80 km/h. Our results showed that GAA600 and CrN treatments decreased the muscle ROS level and MDA content (P < 0.05) and increased the mitochondrial membrane potential (P < 0.001), as well as a higher mRNA expression of avUCP (P < 0.001) and lower mRNA expressions of Nrf2 (P < 0.001), Nrf2 and PGC-1α (P < 0.05) compared with T3h group. Meanwhile, the mRNA and protein expressions of Nrf1, TFAM, and PGC-1α in CrN600 and CrN900 groups were lower than those in the T3h group (P < 0.05). Conclusively, dietary supplementation with GAA and CrN decreased muscle oxidative products and enhanced mitochondrial uncoupling mechanism and mtDNA copy number, which relieved muscle oxidative damage and maintained mitochondrial function.

Toxic dinoflagellate Karenia mikimotoi induces apoptosis in Neuro-2a cells through an oxidative stress-mediated mitochondrial pathway

The dinoflagellate Karenia mikimotoi is a toxic bloom-forming species that threatens aquaculture and public health worldwide. Previous studies showed that K. mikimotoi induces neurotoxicity; however, the underlying mechanism is poorly understood. In this study, three neural cell lines were used to investigate the potential neurotoxicity of K. mikimotoi. The tested cells were exposed to a ruptured cell solution (RCS) of K. mikimotoi at different concentrations (0.5 × 105, 1.0 × 105, 2.0 × 105, 4.0 × 105, and 6 × 105 cells mL-1) for 24 h, and the RCS decreased cell viabilities and promoted Neuro-2a (N2A) cell apoptosis in a dose-dependent manner. The underlying mechanism was further investigated in N2A cells. At the biochemical level, the RCS stimulated reactive oxygen species (ROS) and malondialdehyde (MDA) formation, decreased SOD activity, and reduced mitochondrial membrane potential (MMP). At the gene level, the moderate RCS treatment (2.0 × 105 cells mL-1) upregulated antioxidant response genes (e.g., nrf-2, HO-1, NQO-1, and cat) to alleviate RCS-induced oxidative stress, while the high RCS treatment (4.0 × 105 cells mL-1) downregulated these genes, thereby aggravating oxidative stress. Meanwhile, apoptosis-related genes (e.g., p53, caspase 3, and bax2) were significantly upregulated and the anti-apoptotic gene bcl2 was suppressed after RCS treatment. Western blotting results for Caspase 3, Bax2 and Bcl2 were consistent with the mRNA trends. These results revealed that K. mikimotoi RCS can induce neural cell apoptosis via the oxidative stress-mediated mitochondrial pathway, providing novel insights into the neurotoxicity of K. mikimotoi.

Phenotypic molecular features of long-lived animal species

One of the challenges facing science/biology today is uncovering the molecular bases that support and determine animal and human longevity. Nature, in offering a diversity of animal species that differ in longevity by more than 5 orders of magnitude, is the best 'experimental laboratory' to achieve this aim. Mammals, in particular, can differ by more than 200-fold in longevity. For this reason, most of the available evidence on this topic derives from comparative physiology studies. But why can human beings, for instance, reach 120 years whereas rats only last at best 4 years? How does nature change the longevity of species? Longevity is a species-specific feature resulting from an evolutionary process. Long-lived animal species, including humans, show adaptations at all levels of biological organization, from metabolites to genome, supported by signaling and regulatory networks. The structural and functional features that define a long-lived species may suggest that longevity is a programmed biological property.

Proteomics of the haemolymph of the terrestrial crustacean Porcellio scaber reveals components of its innate immunity under baseline conditions

The terrestrial crustacean Porcellio scaber is an established test organism in environmental research. We analysed the haemolymph proteome of P. scaber using a classical proteomic approach based on one-dimensional gel electrophoresis and tandem mass spectrometry. Using a publicly available protein database and our P. scaber transcriptome data, we have identified 76 proteins involved in cytoskeleton formation, protein degradation, vesicular transport, genetic information processing, detoxification, carbohydrate and lipid metabolism reflecting haemocyte metabolic activity, active intracellular transport, and intercellular communication. Compared with the data reported for other crustaceans, 28 of these P. scaber proteins have been linked to its immunity, among them hemocyanin, α-2-macroglobulin, phenoloxidase 3, superoxide dismutase, glutathione S-transferase, haemolymph clottable protein, and histones H4 and H2B. Our results thus provide a firm base for studying the innate immune response of P. scaber at the level of the haemolymph proteome. This knowledge is of particular importance in ecotoxicity studies with various environmental stressors where understanding physiological changes is important to reveal possible modes of action.

Fitness correlates of blubber oxidative stress and cellular defences in grey seals (Halichoerus grypus): support for the life-history-oxidative stress theory from an animal model of simultaneous lactation and fasting

Life-history-oxidative stress theory predicts that elevated energy costs during reproduction reduce allocation to defences and increase cellular stress, with fitness consequences, particularly when resources are limited. As capital breeders, grey seals are a natural system in which to test this theory. We investigated oxidative damage (malondialdehyde (MDA) concentration) and cellular defences (relative mRNA abundance of heat shock proteins (Hsps) and redox enzymes (REs)) in blubber of wild female grey seals during the lactation fast (n = 17) and summer foraging (n = 13). Transcript abundance of Hsc70 increased, and Nox4, a pro-oxidant enzyme, decreased throughout lactation. Foraging females had higher mRNA abundance of some Hsps and lower RE transcript abundance and MDA concentrations, suggesting they experienced lower oxidative stress than lactating mothers, which diverted resources into pup rearing at the expense of blubber tissue damage. Lactation duration and maternal mass loss rate were both positively related to pup weaning mass. Pups whose mothers had higher blubber glutathione-S-transferase (GST) expression at early lactation gained mass more slowly. Higher glutathione peroxidase (GPx) and lower catalase (CAT) were associated with longer lactation but reduced maternal transfer efficiency and lower pup weaning mass. Cellular stress, and the ability to mount effective cellular defences, could proscribe lactation strategy in grey seal mothers and thus affect pup survival probability. These data support the life-history-oxidative stress hypothesis in a capital breeding mammal and suggest lactation is a period of heightened vulnerability to environmental factors that exacerbate cellular stress. Fitness consequences of stress may thus be accentuated during periods of rapid environmental change.

Novel Therapeutic Approaches to Liver Fibrosis Based on Targeting Oxidative Stress

Chronic liver disease (CLD) constitutes a growing global health issue, with no effective treatments currently available. Oxidative stress closely interacts with other cellular and molecular processes to trigger stress pathways in different hepatic cells and fuel the development of liver fibrosis. Therefore, inhibition of reactive oxygen species (ROS)-mediated effects and modulation of major antioxidant responses to counteract oxidative stress-induced damage have emerged as interesting targets to prevent or ameliorate liver injury. Although many preclinical studies have shown that dietary supplements with antioxidant properties can significantly prevent CLD progression in animal models, this strategy has not proved effective to significantly reduce fibrosis when translated into clinical trials. Novel and more specific therapeutic approaches are thus required to alleviate oxidative stress and reduce liver fibrosis. We have reviewed the relevant literature concerning the crucial role of alterations in redox homeostasis in different hepatic cell types during the progression of CLD and discussed current pharmacological approaches to ameliorate fibrosis by reducing oxidative stress focusing on selective modulation of enzymatic oxidant sources, antioxidant systems and ROS-mediated pathogenic processes.

The Critical Assessment of Oxidative Stress Parameters as Potential Biomarkers of Carbon Monoxide Poisoning

In conventional clinical toxicology practice, the blood level of carboxyhemoglobin is a biomarker of carbon monoxide (CO) poisoning but does not correspond to the complete clinical picture and the severity of the poisoning. Taking into account articles suggesting the relationship between oxidative stress parameters and CO poisoning, it seems reasonable to consider this topic more broadly, including experimental biochemical data (oxidative stress parameters) and patients poisoned with CO. This article aimed to critically assess oxidative-stress-related parameters as potential biomarkers to evaluate the severity of CO poisoning and their possible role in the decision to treat. The critically set parameters were antioxidative, including catalase, 2,2-diphenyl-1-picryl-hydrazyl, glutathione, thiol and carbonyl groups. Our preliminary studies involved patients (n = 82) admitted to the Toxicology Clinical Department of the University Hospital of Jagiellonian University Medical College (Kraków, Poland) during 2015-2020. The poisoning was diagnosed based on medical history, clinical symptoms, and carboxyhemoglobin blood level. Blood samples for carboxyhemoglobin and antioxidative parameters were collected immediately after admission to the emergency department. To evaluate the severity of the poisoning, the Pach scale was applied. The final analysis included a significant decrease in catalase activity and a reduction in glutathione level in all poisoned patients based on the severity of the Pach scale: I°-III° compared to the control group. It follows from the experimental data that the poisoned patients had a significant increase in level due to thiol groups and the 2,2-diphenyl-1-picryl-hydrazyl radical, with no significant differences according to the severity of poisoning. The catalase-to-glutathione and thiol-to-glutathione ratios showed the most important differences between the poisoned patients and the control group, with a significant increase in the poisoned group. The ratios did not differentiate the severity of the poisoning. The carbonyl level was highest in the control group compared to the poisoned group but was not statistically significant. Our critical assessment shows that using oxidative-stress-related parameters to evaluate the severity of CO poisoning, the outcome, and treatment options is challenging.

Stress tolerance in entomopathogenic nematodes: Engineering superior nematodes for precision agriculture

Entomopathogenic nematodes (EPNs) are soil-dwelling parasitic roundworms commonly used as biocontrol agents of insect pests in agriculture. EPN dauer juveniles locate and infect a host in which they will grow and multiply until resource depletion. During their free-living stage, EPNs face a series of internal and environmental stresses. Their ability to overcome these challenges is crucial to determine their infection success and survival. In this review, we provide a comprehensive overview of EPN response to stresses associated with starvation, low/elevated temperatures, desiccation, osmotic stress, hypoxia, and ultra-violet light. We further report EPN defense strategies to cope with biotic stressors such as viruses, bacteria, fungi, and predatory insects. By comparing the genetic and biochemical basis of these strategies to the nematode model Caenorhabditis elegans, we provide new avenues and targets to select and engineer precision nematodes adapted to specific field conditions.

The Relationship between Lifespan of Marine Bivalves and Their Fatty Acids of Mitochondria Lipids

Marine bivalves belonging to the Mytilidae and Pectinidae Families were used in this research. The specific objectives of this study were: to determine the Fatty Acids (FAs) of mitochondrial gill membranes in bivalves with different lifespans, belonging to the same family, and to calculate their peroxidation index; to compare the levels of ROS generation, malondialdehyde (MDA), and protein carbonyls in the mitochondria of gills, in vitro, during the initiation of free-radical oxation; to investigate whether the FAs of mitochondria gill membranes affect the degree of their oxidative damage and the maximum lifespan of species (MLS). The qualitative membrane lipid composition was uniform in the studied marine bivalves, regardless of their MLS. In terms of the quantitative content of individual FAs, the mitochondrial lipids differed significantly. It is shown that lipid matrix membranes of the mitochondria of long-lived species are less sensitive to in vitro-initiated peroxidation compared with the medium and short-lived species. The differences in MLS are related to the peculiarities of FAs of mitochondrial membrane lipids.

Biochemical Effects of Heavy Metals and Organochlorine Compounds Accumulated in Different Tissues of Yellow-Legged Gulls (Larus Michahellis)

In the present study, livers, kidneys and adipose tissue of Yellow-legged Gull (Larus michahellis) were collected. Samples were used to determine relationships between heavy metals/metalloids in liver and kidneys (Hg, Cd, Pb, Se and As) or persistent organic pollutants in adipose tissue (7 PCBs and 11 organochlorine pesticides) with biomarkers of oxidative stress (CAT, GPx, GR, GSH, GST, MDA) analysed in both internal organs. Three possible influencing variables have been studied: age, sex and sampling area. As a result, statistically significant differences (P < 0.05, P < 0.01) were only found according to the sampling area, with differences among the three studied areas found in both organs. Significant positive correlations (P < 0.01) were found in liver (Hg vs. GST; Se vs. MDA) and in kidney (As vs. GR; As vs. GPx; PCB52 vs. CAT; PCB138 vs. CAT). The scarcity in correlations suggests that the levels of pollutants found in animals were not high enough to trigger an effect at the oxidative level.

Enzymatic responses reveal different physiological strategies employed by eurytolerant fish during extreme hot and cold cycling acclimation temperatures

Heat waves and cold snaps are projected to rise in magnitude, duration, interval, and harshness in the coming years. The current literature examining thermal impacts on the physiology of organisms rarely uses chronic, variable thermal acclimations despite the fact that climate change predictions project a more variable environment. If we are to determine species' susceptibility to climate change, chronic and variable lab acclimations should be prioritized. Here, we acclimated the eurytolerant sheepshead minnow (Cyprinodon variegatus) to two extreme cycling thermal regimes: one warm [resting 27 °C with a spike to 33 °C for 8 h daily], one cold [resting 6.5 °C with a spike to 12 °C for 8 h daily], and three chronically stable conditions (10, 22, and 30 °C) for comparison. We measured enzymatic antioxidants (catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx)), total antioxidant capacity, lipid peroxidation (LPO) damage, and citrate synthase (CS) activity in white epaxial muscle. Of particular note, we found significant increases in log CAT activity and SOD concentration in the warm cycling temperatures, and significant increases in GPx activity in the cold cycling temperatures. We found no significant accumulation of LPO damage in any of our thermal acclimation treatments. Thus, sheepshead minnows demonstrate two particularly different mechanisms towards dealing with thermal variation in low and high temperatures. The enzymatic differences between low and high cycling temperatures may define pathways of eurytolerant organisms and how they may survive predicted variability in thermal regimes.

Social status influences relationships between hormones and oxidative stress in a cichlid fish

An individual's social environment can have widespread effects on their physiology, including effects on oxidative stress and hormone levels. Many studies have suggested that variation in oxidative stress experienced by individuals of different social statuses might be due to endocrine differences, however, few studies have evaluated this hypothesis. Here, we assessed whether a suite of markers associated with oxidative stress in different tissues (blood/plasma, liver, and gonads) had social status-specific relationships with circulating testosterone or cortisol levels in males of a cichlid fish, Astatotilapia burtoni. Across all fish, blood DNA damage (a global marker of oxidative stress) and gonadal synthesis of reactive oxygen species [as indicated by NADPH-oxidase (NOX) activity] were lower when testosterone was high. However, high DNA damage in both the blood and gonads was associated with high cortisol in subordinates, but low cortisol in dominants. Additionally, high cortisol was associated with greater production of reactive oxygen species (greater NOX activity) in both the gonads (dominants only) and liver (dominants and subordinates). In general, high testosterone was associated with lower oxidative stress across both social statuses, whereas high cortisol was associated with lower oxidative stress in dominants and higher oxidative stress in subordinates. Taken together, our results show that differences in the social environment can lead to contrasting relationships between hormones and oxidative stress.

Glucose oxidase as an alternative to antibiotic growth promoters improves the immunity function, antioxidative status, and cecal microbiota environment in white-feathered broilers

This study aimed to demonstrate the effects of glucose oxidase (GOD) on broilers as a potential antibiotic substitute. A total of four hundred twenty 1-day-old male Cobb500 broilers were randomly assigned into five dietary treatments, each with six replicates (12 chicks per replicate). The treatments included two control groups (a basal diet and a basal diet with 50 mg/kg aureomycin) and three GOD-additive groups involving three different concentrations of GOD. Analysis after the t-test showed that, on day 21, the feed:gain ratio significantly decreased in the 1,200 U/kg GOD-supplied group (GOD1200) compared to the antibiotic group (Ant). The same effect was also observed in GOD1200 during days 22-42 and in the 600 U/kg GOD-supplied group (GOD600) when compared to the control group (Ctr). The serum tests indicated that, on day 21, the TGF-β cytokine was significantly decreased in both GOD600 and GOD1200 when compared with Ctr. A decrease in malondialdehyde and an increase in superoxide dismutase in GOD1200 were observed, which is similar to the effects seen in Ant. On day 42, the D-lactate and glutathione peroxidase activity changed remarkably in GOD1200 and surpassed Ant. Furthermore, GOD upregulated the expression of the jejunal barrier genes (MUC-2 and ZO-1) in two phases relative to Ctr. In the aureomycin-supplied group, the secretory immunoglobulin A significantly decreased in the jejunum at 42 days. Changes in microbial genera were also discovered in the cecum by sequencing 16S rRNA genes at 42 days. The biomarkers for GOD supplementation were identified as Colidextribacter, Oscillibacter, Flavonifractor, Oscillospira, and Shuttleworthia. Except for Shuttleworthia, all the abovementioned genera were n-butyrate producers known for imparting their various benefits to broilers. The PICRUSt prediction of microbial communities revealed 11 pathways that were enriched in both the control and GOD-supplied groups. GOD1200 accounted for an increased number of metabolic pathways, demonstrating their potential in aiding nutrient absorption and digestion. In conclusion, a diet containing GOD can be beneficial to broiler health, particularly at a GOD concentration of 1,200 U/kg. The improved feed conversion ratio, immunity, antioxidative capacity, and intestinal condition demonstrated that GOD could be a valuable alternative to antibiotics in broiler breeding.

Higher temperature induces oxidative stress in hybrids but not in parental species: A case study of crested newts

Ectotherms are particularly sensitive to global warming due to their limited capacity to thermoregulate, which can impact their performance and fitness. From a physiological standpoint, higher temperatures often enhance biological processes that can induce the production of reactive oxygen species and result in a state of cellular oxidative stress. Temperature alters interspecific interactions, including species hybridization. Hybridization under different thermal conditions could amplify parental (genetic) incompatibilities, thus affecting a hybrid's development and distribution. Understanding the impact of global warming on the physiology of hybrids and particularly their oxidative status could help in predicting future scenarios in ecosystems and in hybrids. In the present study, we investigated the effect of water temperature on the development, growth and oxidative stress of two crested newt species and their reciprocal hybrids. Larvae of Triturus macedonicus and T. ivanbureschi, and their T. macedonicus-mothered and T. ivanbureschi-mothered hybrids were exposed for 30 days to temperatures of 19°C and 24°C. Under the higher temperature, the hybrids experienced increases in both growth and developmental rates, while parental species exhibited accelerated growth (T. macedonicus) or development (T. ivanbureschi). Warm conditions also had different effects on the oxidative status of hybrid and parental species. Parental species had enhanced antioxidant responses (catalase, glutathione peroxidase, glutathione S-transferase and SH groups), which allowed them to alleviate temperature-induced stress (revealed by the absence of oxidative damage). However, warming induced an antioxidant response in the hybrids, including oxidative damage in the form of lipid peroxidation. These findings point to a greater disruption of redox regulation and metabolic machinery in hybrid newts, which can be interpreted as the cost of hybridization that is likely linked to parental incompatibilities expressed under a higher temperature. Our study aims to improve mechanistic understanding of the resilience and distribution of hybrid species that cope with climate-driven changes.

Sublethal cadmium exposure in the freshwater snail Lymnaea stagnalis meets a deficient, poorly responsive metallothionein system while evoking oxidative and cellular stress

The Great Pond snail Lymnaea stagnalis (Gastropoda, Hygrophila) is a wide-spread freshwater gastropod, being considered as a model organism for research in many fields of biology, including ecotoxicology. The aim of the present study was to explore the Cd sensitivity of L. stagnalis through the measurement of a biomarker battery for oxidative, toxic and cellular stress. The interpretation of biomarker parameters occurred against the background of a truncated metallothionein protein with a limited Cd-binding capacity. Individuals of L. stagnalis were exposed through 14 days to uncontaminated water (controls) or to low (30 μg · L^-1) or high (50 μg · L^-1) Cd concentrations. The digestive gland of control and low-Cd exposed snails was processed for transcriptional analysis of the Metallothionein (MT) gene expression, and for determination of biomarkers for oxidative stress, toxicity and cellular stress. Digestive gland supernatants of high-Cd exposed snails were subjected to chromatography and subsequent analysis by spectrophotometry. It was shown that the MT system of L. stagnalis is functionally deficient, with a poor Cd responsiveness at both, the transcriptional and the protein expression levels. Instead, L. stagnalis appears to rely on alternative detoxification mechanisms such as Cd binding by phytochelatins and metal inactivation by compartmentalization within the lysosomal system. In spite of this, however, traces of Cd apparently leak out of the pre-determined detoxification pathways, leading to adverse effects, which is clearly indicated by biomarkers of oxidative and cellular stress.

Interaction Of Inflammatory Parameters And Thiol/Disulfide System Of Antioxidant Protection In Chronic Obstructive Pulmonary Disease

Introduction — Increased incidence and prevalence of chronic obstructive pulmonary disease (COPD) provides rationale for describing the disease progression mechanism, considering the interaction of key participants of this process. The objective of our study was to establish the dysfunction parameters of thiol/disulfide system components and adaptive immunity unit in patients with stable chronic obstructive pulmonary disease (COPD). Material and Methods — We examined patients with stable COPD of moderate (62 subjects) or severe (50 subjects) grades. The control group included 32 subjects. Prooxidant and antioxidant markers of oxidative stress were investigated with ELISA. We determined cytokine levels in blood plasma and the number of T helper cells expressing IL-6R with flow cytometry (BD FACSCanto II, USA). Correlation pleiads sensu Terentiev were employed to visualize the data. Results — Changes in both antioxidant and cytokine status of subjects with COPD of varying severity grades implied the progression of systemic inflammation in conditions of uncontrolled activation of adaptive immunity unit rather than just a shift in the peroxide balance and an increase in oxygen metabolites. Conclusion — Accumulation of biomolecule peroxidation products, imbalance in the prooxidant-antioxidant system, and a change in pathogenetic mechanism of inflammation could lead to an aggravated course of bronchopulmonary pathology.

Phyllanthus emblica (Amla) Fruit Powder as a Supplement to Improve Preweaning Dairy Calves' Health: Effect on Antioxidant Capacity, Immune Response, and Gut Bacterial Diversity

Disease is the main reason for the use of antimicrobials in calf rearing, and antibiotics are commonly used to treat calves, including for unknown diseases. This leads to antimicrobial resistance, which is a challenge to the livestock industry and public health. Plant products containing high levels of phytochemicals may improve the immunity and resistance of calves against infections, thereby reducing the use of antimicrobials. This study aimed to investigate the effect of Phyllanthus emblica (Amla) fruit powder (PE) supplementation on antioxidant capacity and immune response of preweaning dairy calves. One hundred, 2-day-old, male Holstein calves were randomly assigned into five treatment groups receiving 0, 5, 10, 20, and 40 g/d PE supplementation. Antioxidant and immune indices and pro- and anti-inflammatory cytokines were analyzed from serum samples, whereas 16S rRNA was analyzed from rumen fluid and fecal samples. PE supplementation, at 5 g/d, protected calves against oxidative stress and improved antioxidant enzymes and immune and anti-inflammatory responses, showing its immunity-enhancing and protective roles against infections. However, the antioxidant capacity and immune response decreased with increasing PE levels, illustrating the adverse effects of PE supplementation at higher doses. The analysis of ruminal and fecal bacterial community abundance detected higher proportions of Firmicutes at an early age, and a higher Bacteroidetes to Firmicutes ratio at weaning, in calves supplemented with 5 g/d PE. This contributed to the development of the immune system in early life, and improved immune and anti-inflammatory responses at a later age. The overall results suggest that PE could be supplemented at 5 g/d for preweaning dairy calves to protect against oxidative stress and infections while maintaining normal gut microbial hemostasis.

How telomere dynamics are influenced by the balance between mitochondrial efficiency, reactive oxygen species production and DNA damage

It is well known that oxidative stress is a major cause of DNA damage and telomere attrition. Most endogenous reactive oxygen species (ROS) are produced in the mitochondria, producing a link between mitochondrial function, DNA integrity and telomere dynamics. In this review we will describe how ROS production, rates of damage to telomeric DNA and DNA repair are dynamic processes. The rate of ROS production depends on mitochondrial features such as the level of inner membrane uncoupling and the proportion of time that ATP is actively being produced. However, the efficiency of ATP production (the ATP/O ratio) is positively related to the rate of ROS production, so leading to a trade-off between the body's energy requirements and its need to prevent oxidative stress. Telomeric DNA is especially vulnerable to oxidative damage due to features such as its high guanine content; while repair to damaged telomere regions is possible through a range of mechanisms, these can result in more rapid telomere shortening. There is increasing evidence that mitochondrial efficiency varies over time and with environmental context, as do rates of DNA repair. We argue that telomere dynamics can only be understood by appreciating that the optimal solution to the trade-off between energetic efficiency and telomere protection will differ between individuals and will change over time, depending on resource availability, energetic demands and life history strategy.

Reduced Fitness and Elevated Oxidative Stress in the Marine Copepod Tigriopus japonicus Exposed to the Toxic Dinoflagellate Karenia mikimotoi

Blooms of the toxic dinoflagellate Karenia mikimotoi cause devastation to marine life, including declines of fitness and population recruitment. However, little is known about the effects of them on benthic copepods. Here, we assessed the acute and chronic effects of K. mikimotoi on the marine benthic copepod Tigriopus japonicus. Results showed that adult females maintained high survival (>85%) throughout 14-d incubation, but time-dependent reduction of survival was detected in the highest K. mikimotoi concentration, and nauplii and copepodites were more vulnerable compared to adults. Ingestion of K. mikimotoi depressed the grazing of copepods but significantly induced the generation of reactive oxygen species (ROS), total antioxidant capacity, activities of antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase), and acetylcholinesterase. Under sublethal concentrations for two generations, K. mikimotoi reduced the fitness of copepods by prolonging development time and decreasing successful development rate, egg production, and the number of clutches. Our findings suggest that the bloom of K. mikimotoi may threaten copepod population recruitment, and its adverse effects are associated with oxidative stress.

Role of Oxidative Stress in Liver Disorders

Oxygen is vital for life as it is required for many different enzymatic reactions involved in intermediate metabolism and xenobiotic biotransformation. Moreover, oxygen consumption in the electron transport chain of mitochondria is used to drive the synthesis of ATP to meet the energetic demands of cells. However, toxic free radicals are generated as byproducts of molecular oxygen consumption. Oxidative stress ensues not only when the production of reactive oxygen species (ROS) exceeds the endogenous antioxidant defense mechanism of cells, but it can also occur as a consequence of an unbalance between antioxidant strategies. Given the important role of hepatocytes in the biotransformation and metabolism of xenobiotics, ROS production represents a critical event in liver physiology, and increasing evidence suggests that oxidative stress contributes to the development of many liver diseases. The present review, which is part of the special issue “Oxidant stress in Liver Diseases”, aims to provide an overview of the sources and targets of ROS in different liver diseases and highlights the pivotal role of oxidative stress in cell death. In addition, current antioxidant therapies as treatment options for such disorders and their limitations for future trial design are discussed.

Alveolar Type II Cell Damage and Nrf2-SOD1 Pathway Downregulation Are Involved in PM2.5-Induced Lung Injury in Rats

The general toxicity of fine particulate matter (PM_2.5) has been intensively studied, but its pulmonary toxicities are still not fully understood. To investigate the changes of lung tissue after PM_2.5 exposure and identify the potential mechanisms of pulmonary toxicity, PM_2.5 samples were firstly collected and analyzed. Next, different doses of PM_2.5 samples (5 mg/kg, 10 mg/kg, 20 mg/kg) were intratracheally instilled into rats to simulate lung inhalation of polluted air. After instillation for eight weeks, morphological alterations of the lung were examined, and the levels of oxidative stress were detected. The data indicated that the major contributors to PM_2.5 mass were organic carbon, elemental carbon, sulfate, nitrate, and ammonium. Different concentrations of PM_2.5 could trigger oxidative stress through increasing reactive oxygen species (ROS) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels, and decreasing expression of antioxidant-related proteins (nuclear factor erythroid 2-related factor 2 (Nrf2), superoxide dismutase 1 (SOD1) and catalase). Histochemical staining and transmission electron microscopy displayed pulmonary inflammation, collagen deposition, mitochondrial swelling, and a decreasing number of multilamellar bodies in alveolar type II cells after PM_2.5 exposure, which was related to PM_2.5-induced oxidative stress. These results provide a basis for a better understanding of pulmonary impairment in response to PM_2.5.

Nanoplastics and Microplastics May Be Damaging Our Livers

Plastics in the environment can be degraded and even broken into pieces under the action of natural factors, and the degraded products with a particle size of less than 5 mm are called microplastics (MPs). MPs exist in a variety of environmental media that come into contact with the human body. It can enter the body through environmental media and food chains. At present, there are many studies investigating the damage of MPs to marine organisms and mammals. The liver is the largest metabolizing organ and plays an important role in the metabolism of MPs in the body. However, there is no available systematic review on the toxic effects of MPs on the liver. This paper summarizes the adverse effects and mechanisms of MPs on the liver, by searching the literature and highlighting the studies that have been published to date, and provides a scenario for the liver toxicity caused by MPs.

Effects of air pollution on human health - Mechanistic evidence suggested by in vitro and in vivo modelling

Airborne particulate matter (PM) comprises both solid and liquid particles, including carbon, sulphates, nitrate, and toxic heavy metals, which can induce oxidative stress and inflammation after inhalation. These changes occur both in the lung and systemically, due to the ability of the small-sized PM (i.e. diameters ≤2.5 μm, PM_2.5) to enter and circulate in the bloodstream. As such, in 2016, airborne PM caused ∼4.2 million premature deaths worldwide. Acute exposure to high levels of airborne PM (eg. during wildfires) can exacerbate pre-existing illnesses leading to hospitalisation, such as in those with asthma and coronary heart disease. Prolonged exposure to PM can increase the risk of non-communicable chronic diseases affecting the brain, lung, heart, liver, and kidney, although the latter is less well studied. Given the breadth of potential disease, it is critical to understand the mechanisms underlying airborne PM exposure-induced disorders. Establishing aetiology in humans is difficult, therefore, in-vitro and in-vivo studies can provide mechanistic insights. We describe acute health effects (e.g. exacerbations of asthma) and long term health effects such as the induction of chronic inflammatory lung disease, and effects outside the lung (e.g. liver and renal change). We will focus on oxidative stress and inflammation as this is the common mechanism of PM-induced disease, which may be used to develop effective treatments to mitigate the adverse health effect of PM exposure.

Effects of Ultraviolet Radiation on Sediment Burial Parameters and Photo-Oxidative Response of the Intertidal Anemone Anthopleura hermaphroditica

Anthopleura hermaphroditica is an intertidal anemone that lives semi-buried in soft sediments of estuaries and releases its brooded embryos directly to the benthos, being exposed to potentially detrimental ultraviolet radiation (UVR) levels. In this study, we investigated how experimental radiation (PAR: photosynthetically active radiation; UVA: ultraviolet A radiation; and UVB: ultraviolet B radiation) influences burrowing (time, depth and speed) in adults and juveniles when they were exposed to PAR (P, 400–700 nm), PAR + UVA (PA, 315–700 nm) and PAR + UVA + UVB (PAB, 280–700 nm) experimental treatments. The role of sediment as a physical shield was also assessed by exposing anemones to these radiation treatments with and without sediment, after which lipid peroxidation, protein carbonyls and total antioxidant capacity were quantified. Our results indicate that PAB can induce a faster burial response compared to those anemones exposed only to P. PAB increased oxidative damage, especially in juveniles where oxidative damage levels were several times higher than in adults. Sediment offers protection to adults against P, PA and PAB, as significant differences in their total antioxidant capacity were observed compared to those anemones without sediment. Conversely, the presence or absence of sediment did not influence total antioxidant capacity in juveniles, which may reflect that those anemones have sufficient antioxidant defenses to minimize photooxidative damage due to their reduced tolerance to experimental radiation. Burrowing behavior is a key survival skill for juveniles after they have been released after brooding.

Physiological and behavioural strategies of aquatic animals living in fluctuating environments

Shallow or near-shore environments, such as ponds, estuaries and intertidal zones, are among the most physiologically challenging of all aquatic settings. Animals inhabiting these environments experience conditions that fluctuate markedly over relatively short temporal and spatial scales. Living in these habitats requires the ability to tolerate the physiological disturbances incurred by these environmental fluctuations. This tolerance is achieved through a suite of physiological and behavioural responses that allow animals to maintain homeostasis, including the ability to dynamically modulate their physiology through reversible phenotypic plasticity. However, maintaining the plasticity to adjust to some stresses in a dynamic environment may trade off with the capacity to deal with other stressors. This paper will explore studies on select fishes and invertebrates exposed to fluctuations in dissolved oxygen, salinity and pH. We assess the physiological mechanisms these species employ to achieve homeostasis, with a focus on the plasticity of their responses, and consider the resulting physiological trade-offs in function. Finally, we discuss additional factors that may influence organismal responses to fluctuating environments, such as the presence of multiple stressors, including parasites. We echo recent calls from experimental biologists to consider physiological responses to life in naturally fluctuating environments, not only because they are interesting in their own right but also because they can reveal mechanisms that may be crucial for living with increasing environmental instability as a consequence of climate change.

Effects of Red Ginseng Byproducts on Rumen Fermentation, Growth Performance, Blood Metabolites, and mRNA Expression of Heat Shock Proteins in Heat-Stressed Fattening Hanwoo Steers

The objective of this study was to evaluate the effects of dietary supplementation with red ginseng byproduct (RGB) on rumen fermentation, growth performance, blood metabolites, and mRNA expression of heat shock proteins (HSP) in fattening Hanwoo steers under heat stress. Two experimental total mixed rations (TMR) were prepared: (1) a TMR meeting the requirement of fattening beef having an average daily gain (ADG) 0.8 kg/day (CON) and (2) a TMR that included 2% RGB on a dry matter (DM) basis (GINSENG). In vitro rumen fermentation and in vivo growth experiments were conducted using two experimental diets. A total of 22 Hanwoo steers were distributed to two treatments (CON vs. GINSENG) in a completely randomized block design according to body weight (BW). The experiment was conducted during the summer season for five weeks. The final BW, ADG, DM intake, and feed conversion ratio did not differ between treatments in the growth trial. In the mRNA expression results, only HSP 90 showed an increasing tendency in the GINSENG group. The use of 2%DM RGB did not improve the growth performance or alleviate heat stress in fattening Hanwoo steers during the summer season.

Fungal and oomycete pathogens and heavy metals: an inglorious couple in the environment

Heavy metal (HM) contamination of the environment is a major problem worldwide. The rate of global deposition of HMs in soil has dramatically increased over the past two centuries and there of facilitated their rapid accumulation also in living systems. Although the effects of HMs on plants, animals and humans have been extensively studied, yet little is known about their effects on the (patho)biology of the microorganisms belonging to a unique group of filamentous eukaryotic pathogens, i.e., fungi and oomycetes. Much of the literature concerning mainly model species has revealed that HM stress affects their hyphal growth, morphology, and sporulation. Toxicity at cellular level leads to disturbance of redox homeostasis manifested by the formation of nitro-oxidative intermediates and to the induction of antioxidant machinery. Despite such adverse effects, published data is indicative of the fact that fungal and oomycete pathogens have a relatively high tolerance to HMs in comparison to other groups of microbes such as bacteria. Likely, these pathogens may harbor a network of detoxification mechanisms that ensure their survival in a highly HM-polluted (micro)habitat. Such a network may include extracellular HMs immobilization, biosorption to cell wall, and/or their intracellular sequestration to proteins or other ligands. HMs may also induce a hormesis-like phenomenon allowing the pathogens to maintain or even increase fitness against chemical challenges. Different scenarios linking HMs stress and modification of the microorganisms pathogenicity are disscused in this review.

Effects of graphene oxide nanosheets in the polychaete Hediste diversicolor: Behavioural, physiological and biochemical responses

Numerous applications exist for graphene-based materials, such as graphene oxide (GO) nanosheets. Increased concentrations of GO nanosheets in the environment have the potential to have a large negative effect on the aquatic environment, with consequences for benthic organisms, such as polychaetes. The polychaete Hediste diversicolor mobilises the sediments, hence altering the availability of contaminants and the nutrients biogeochemical cycle. As such, this study proposes to assess the effects of different GO nanosheet concentrations on the behaviour, feeding activity, mucus production, regenerative capacity, antioxidant status, biochemical damage and metabolism of H. diversicolor. This study evidenced that H. diversicolor exposed to GO nanosheets had a significantly lower ability to regenerate their bodies, took longer to feed and burrow into the sediment and produced more mucus. Membrane oxidative damage (lipid peroxidation) increased in exposed specimens. The increased metabolic rate (ETS) evidenced a higher energy expenditure in exposed organisms (high use of ready energy sources - soluble sugars) to fight the toxicity induced by GO nanosheets, such as SOD activity. The increase in SOD activity was enough to reduce reactive oxygen species (ROS) induced by GO on cytosol at the lowest concentrations, avoiding the damage on proteins (lower PC levels), but not on membranes (LPO increase). This study revealed that the presence of GO nanosheets, even at the lower levels tested, impaired behavioural, physiological, and biochemical traits in polychaetes, suggesting that the increase of this engineered nanomaterial in the environment can disturb these benthic organisms, affecting the H. diversicolor population. Moreover, given the important role of this group of organisms in coastal and estuarine food webs, the biogeochemical cycle of nutrients, and sediment oxygenation, there is a real possibility for repercussions into the estuarine community.

A 5-Year Prospective Study on Incidence and Clinico-pathological Changes Associated with Naturally Occurring Trypanosomosis in Dogs of Mizoram, India

PURPOSE

The present research was taken to study the hospital-based incidence and clinico-pathological changes associated with naturally occurring trypanosomosis in dogs of Mizoram.

METHODS

A 5-year prospective study on hospital-based incidence and clinico-pathological changes associated with naturally occurring trypanosomosis in dogs of Mizoram was carried out during the study period from April, 2015 to March, 2020. Trypanosoma evansi infection was confirmed by microscopic examination and polymerase chain reaction (PCR). Non-infected clinically healthy dogs (n = 6) served as control. Blood samples were collected to study the haemogram and serum samples were used for the evaluation of serum biochemical parameters and oxidant-antioxidant parameters.

RESULTS

During the study period, an overall incidence of 0.25% was recorded for trypanosomosis in dogs. The most consistent clinical findings noticed were anorexia/inappetence, pyrexia, depression/lethargy, pale mucous membrane, dehydration and lymphadenomegaly. Anaemia, granulocytopenia, lymphocytosis and thrombocytopenia were the major findings noticed in trypanosomosis affected dogs. The profile of vital organ function revealed that the mean values of total protein, albumin and random blood glucose were significantly (P < 0.05) lower, whereas the mean values of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total bilirubin, blood urea nitrogen (BUN) and creatinine were significantly (P < 0.05) higher in dogs affected with trypanosomosis. The mean value of lipid hydroperoxide (LPO) was significantly (P < 0.05) higher, whereas the mean values of glutathione (GSH), superoxide dismutase (SOD) and total antioxidant activity (TAOA) were significantly (P < 0.05) lower in trypanosomosis affected dogs. When total erythrocyte count (TEC) was correlated with LPO (r = - 0.631, P < 0.05), a negative correlation was found, while in case of GSH (r = 0.757, P < 0.05), SOD (r = 0.767, P < 0.05) and TAOA (r = 0.713, P < 0.05), it was positively correlated.

CONCLUSION

A negative correlation of TEC count with LPO, while a positive correlation with GSH, SOD and TAOA signify the role of oxidative stress in the pathogenesis of anaemia induced by T. evansi infection in dogs. The present study findings might be helpful to clinicians when treating clinical cases of this kind. Incorporation of organ protective drugs and antioxidants in the treatment schedule may result in better prognosis.

The oxidative cost of helping and its minimization in a cooperative breeder

Cooperative actions are beneficial to the group, but presumably costly to the individual co-operators. In cooperatively breeding species, helping to raise young is thought to involve important energetic costs, which could lead to elevated exposure to reactive oxygen species, resulting in oxidative stress. However, identifying such costs can be difficult if individuals adjust their investment in helping in relation to environmental conditions or their own physiological condition. Experimental approaches are therefore required to quantify the costs of helping but, to date, these have been infrequent. Here, we combined correlational and experimental data to investigate the oxidative cost of helping-at-the-nest and how this affects helping decisions in wild sociable weavers Philetairus socius, a colonial cooperatively breeding bird. At the correlational level, we found that the probability of helping was influenced by the interaction of an individual’s oxidative state and age: compared to younger birds, older individuals were more likely to help when they had higher oxidative damage, and the opposite trend was found for younger individuals. After experimentally increasing the energetic cost of flight, manipulated helpers in breeding colonies decreased nestling feeding rates and incurred an increase in oxidative damage, which was not present in manipulated helpers in non-breeding colonies. This indicates that individuals decreased their helping behavior to minimize the associated costs. These results suggest that oxidative stress can influence helping decisions and underlie a trade-off between cooperation and self-maintenance, which is central to understanding when helping might take place in this and other species.

Selection signatures for heat tolerance in Brazilian horse breeds

Since domestication, horse breeds have adapted to their environments and differentiated from one another. This paper uses two methods to detect selection signatures in 23 horse breeds, eight of which are Brazilian (610 animals), both cold-blooded and warm-blooded, from temperate and tropical regions. These animals were genotyped using the GGP Equine BeadChip and we analysed the data by Principal Component Analysis (PCA). The samples were separated into groups based on their geographical area of origin and PCA results studied. The genomic regions under selection were detected by hapFLK and PCAdapt methodologies, identifying six regions under selection with at least one Brazilian horse breed. These regions contain genes associated with heat tolerance, skin colour, body size, energy production/metabolism, genes involved in protein degradation/turnover/DNA repair, genes reducing the impact of oxidative stress/cellular repair, and transcriptional regulation. This work confirmed LCORL and NCAPG gene regions in previous studies associated with body size on Equine Chromosome Autosome 3 (ECA3). On the same ECA3, a region implicating genes linked to coat colour was identified, also previously related to heat stress. Regions with genes coding heat shock proteins were found on ECA1 and 2, and many candidate genes for oxidation-reduction which are a natural response to heat stress. However, a larger sample size and whole-genome SNPs are needed to understand better and identify new candidate regions as well as their functional relation with heat tolerance.

Antioxidant Responses Induced by Short-Term Activity–Estivation–Arousal Cycle in Pomacea canaliculata

Long-term estivation (45 days) in the apple snail Pomacea canaliculata induces an increase of non-enzymatic antioxidants, such as uric acid and reduced glutathione (GSH), which constitutes an alternative to the adaptive physiological strategy of preparation for oxidative stress (POS). Here, we studied markers of oxidative stress damage, uric acid levels, and non-enzymatic antioxidant capacity, enzymatic antioxidant defenses, such as superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST), and transcription factors expression [forkhead box protein O (FOXO), hypoxia-inducible factor-1 alpha (HIF1α), and nuclear factor erythroid 2-related factor 2 (Nrf2)] in control active animals, 7-day estivating and aroused snails, in digestive gland, gill, and lung tissue samples. In the digestive gland, SOD and CAT activities significantly increased after estivation and decreased during arousal. Meanwhile, GST activity decreased significantly during the activity–estivation–arousal cycle. Gill CAT activity increased significantly at 7 days of estivation, and it decreased during arousal. In the lung, the CAT activity level increased significantly during the cycle. FOXO upregulation was observed in the studied tissues, decreasing its expression only in the gill of aroused animals during the cycle. HIF1α and Nrf2 transcription factors decreased their expression during estivation in the gill, while in the lung and the digestive gland, both transcription factors did not show significant changes. Our results showed that the short-term estivation induced oxidative stress in different tissues of P. canaliculata thereby increasing overall antioxidant enzymes activity and highlighting the role of FOXO regulation as a possible underlying mechanism of the POS strategy.

Oxidative Stability, Carcass Traits, and Muscle Fatty Acid and Amino Acid Profiles in Heat-Stressed Broiler Chickens

The objective was to elucidate the effects of chronic heat stress on carcass traits, muscle oxidative stability, muscle fatty acids and amino acid profiles in broiler chickens. A total of 100-day-old male Ross broiler chicks were divided into two equal groups of five replicates. The control group (TN) was maintained on a thermoneutral condition, while the experimental group (HS) was subjected to 8 h of heat stress (34 °C). The HS group showed lower dressing percentage and breast yield compared with the TN group (p = 0.040 and 0.042, respectively). Meanwhile, heat stress significantly increased the percentage of abdominal fat in broiler chickens (p = 0.001). The HS group showed significantly lower levels of PUFA (linoleic, docosahexaenoic and eicosapentaenoic) in the breast (p = 0.003, 0.002 and 0.001, respectively) and thigh (p = 0.001, 0.009 and 0.003, respectively) muscles than did the TN group. The levels of α-lenolinec acid in the breast and thigh muscles did not differ between both experimental groups (p = 0.818 and 0.060, respectively). With exception of threonine, tyrosine and phenylalanine, the levels of essential AA in the breast muscles were significantly (p ˂ 0.05) reduced in the HS group. The HS group showed significantly higher concentration of malondialdehyde (MDA) in the breast muscles (p = 0.032). Meanwhile, the concentration of MDA in the thigh muscles did not differ between both experimental groups (p = 0.149). Furthermore, the HS group showed significantly lower superoxide dismutase and catalase in heart tissues (p = 0.005 and 0.001, respectively). In conclusion, chronic thermal stress deteriorates carcass yield and the oxidative stability of breast muscles, as well as the levels of PUFA and essential AA in broiler chickens. However, the oxidative stability of thigh muscles was not affected.

Single and combined acute and subchronic toxic effects of microplastics and copper in zebrafish (Danio rerio) early life stages

The evaluation of the interaction between microplastics (MPs) and heavy metals is of special importance for risk assessment. In this study, zebrafish (Danio rerio) were exposed to MPs (2 mg/L), two sub-lethal concentrations of copper (Cu, 60 and 125 μg/L) and their mixtures (Cu60 + MPs, Cu125 + MPs), from 2-h post-fertilization (hpf) until 14-days post-fertilization (dpf). Lethal and sublethal endpoints were evaluated, along with a set of biochemical and genetic biomarkers between 2 and 14 dpf. Exposure to MPs and Cu, single or combined, induced high mortality and oxidative stress in zebrafish larvae, with data showing that the antioxidant enzymes were inhibited at 6 dpf, increasing thereafter until 14 dpf, due to the accumulation of reactive oxygen species. MPs and Cu, single or combined, caused neurotoxicity in larvae by inhibiting acetylcholinesterase activity. There was an increased and significant effect of Cu + MPs groups on the evaluated biomarkers, concerning the corresponding Cu groups, suggesting that MPs may have a synergistic effect in relation to Cu. The Integrated Biomarker Response (IBR) evidenced that a higher degree of stress occurred at the larval period. Our findings highlight that MPs can act as a vector for heavy metals, therefore, influencing their bioavailability and toxicity in the organisms.

Epigallocatechin Gallate Alleviates Down-Regulation of Thioredoxin in Ischemic Brain Damage and Glutamate-Exposed Neuron

Epigallocatechin gallate (EGCG) is one of polyphenol that is abundant in green tea. It has anti-oxidative activity and exerts neuroprotective effects in ischemic brain damage. Ischemic conditions induce oxidative stress and result in cell death. Thioredoxin is a small redox protein that plays an important role in the regulation of oxidation and reduction. This study was designed to investigate the regulation of thioredoxin by EGCG in ischemic brain damage. Middle cerebral artery occlusion (MCAO) was performed to induce focal cerebral ischemia in male Sprague-Dawley rats. The EGCG (50 mg/kg) or was administered before MCAO surgical operation. Neurological behavior test, reactive oxygen species (ROS), and lipid peroxidation (LPO) measurement were performed 24 h after MCAO. The cerebral cortex was isolated for further experiments. EGCG alleviated MCAO-induced neurological deficits and increases in ROS and LPO levels. EGCG also ameliorated the decrease in thioredoxin expression by MCAO. This finding was confirmed using various techniques such as Western blot analysis, reverse transcription PCR, and immunofluorescence staining. Results of immunoprecipitation showed that MCAO decreases the interaction between apoptosis signal-regulating kinase 1 (ASK1) and thioredoxin, while EGCG treatment attenuates this decrease. EGCG also attenuated decrease of cell viability and thioredoxin expression in glutamate-exposed neuron in a dose-dependent manner. It alleviated the increase of caspase-3 by glutamate exposure. However, this effect of EGCG on caspase-3 change was weakened in thioredoxin siRNA-transfected neurons. These findings suggest that EGCG exerts a neuroprotective effect by regulating thioredoxin expression and modulating ASK1 and thioredoxin binding in ischemic brain damage.

Cysteine Proteome Reveals Response to Endogenous Oxidative Stress in Bacillus cereus

At the end of exponential growth, aerobic bacteria have to cope with the accumulation of endogenous reactive oxygen species (ROS). One of the main targets of these ROS is cysteine residues in proteins. This study uses liquid chromatography coupled to high-resolution tandem mass spectrometry to detect significant changes in protein abundance and thiol status for cysteine-containing proteins from Bacillus cereus during aerobic exponential growth. The proteomic profiles of cultures at early-, middle-, and late-exponential growth phases reveals that (i) enrichment in proteins dedicated to fighting ROS as growth progressed, (ii) a decrease in both overall proteome cysteine content and thiol proteome redox status, and (iii) changes to the reduced thiol status of some key proteins, such as the transition state transcriptional regulator AbrB. Taken together, our data indicate that growth under oxic conditions requires increased allocation of protein resources to attenuate the negative effects of ROS. Our data also provide a strong basis to understand the response mechanisms used by B. cereus to deal with endogenous oxidative stress.

Dietary vitamin E reaches the mitochondria in the flight muscle of zebra finches but only if they exercise

Whether dietary antioxidants are effective for alleviating oxidative costs associated with energy-demanding life events first requires they are successfully absorbed in the digestive tract and transported to sites associated with reactive species production (e.g. the mitochondria). Flying birds are under high energy and oxidative demands, and although birds commonly ingest dietary antioxidants in the wild, the bioavailability of these consumed antioxidants is poorly understood. We show for the first time that an ingested lipophilic antioxidant, α-tocopherol, reached the mitochondria in the flight muscles of a songbird but only if they regularly exercise (60 min of perch-to-perch flights two times in a day or 8.5 km day-1). Deuterated α-tocopherol was found in the blood of exercise-trained zebra finches within 6.5 hrs and in isolated mitochondria from pectoral muscle within 22.5 hrs, but never reached the mitochondria in caged sedentary control birds. This rapid pace (within a day) and extent of metabolic routing of a dietary antioxidant to muscle mitochondria means that daily consumption of such dietary sources can help to pay the inevitable oxidative costs of flight muscle metabolism, but only when combined with regular exercise.

Impaired antioxidant defenses and DNA damage in the European glass eel (Anguilla anguilla) exposed to ocean warming and acidification

The European eel (Anguilla anguilla) has attracted scientific inquiry for centuries due to its singular biological traits. Within the European Union, glass eel fisheries have declined sharply since 1980, from up to 2000 t (t) to 62.2 t in 2018, placing wild populations under higher risk of extinction. Among the major causes of glass eels collapse, climate change has become a growing worldwide issue, specifically ocean warming and acidification, but, to our knowledge, data on physiological and biochemical responses of glass eels to these stressors is limited. Within this context, we selected some representative biomarkers [e.g. glutathione peroxidase (GPx), catalase (CAT), total antioxidant capacity (TAC), heat shock proteins (HSP70), ubiquitin (Ub) and DNA damage] to study physiological responses of the European glass eel under distinct laboratory-climate change scenarios, such as increased water temperature (+ 4 °C) and pH reduction (- 0.4 units), for 12 weeks. Overall, the antioxidant enzymatic machinery was impaired, both in the muscle and viscera, manifested by significant changes in CAT, GPx and TAC. Heat shock response varied differently between tissues, increasing with temperature in the muscle, but not in the viscera, and decreasing in both tissues under acidification. The inability of HSP to maintain functional protein conformation was responsible for boosting the production of Ub, particularly under warming and acidification, as sole stressors. The overproduction of reactive oxygen species (ROS), either elicited by warming - due to increased metabolic demand - or acidification - through H⁺ interaction with O₂^-, generating H₂O₂ - overwhelmed defense mechanisms, causing oxidative stress and consequently leading to protein and DNA damage. Our results emphasize the vulnerability of eels' early life stages to climate change, with potential cascading consequences to adult stocks.

A biomimetic natural sciences approach to understanding the mechanisms of ageing in burden of lifestyle diseases

The worldwide landscape of an ageing population and age-related disease brings with it huge socio-economic and public healthcare concerns across nations. Correspondingly, monumental human and financial resources have been invested in biomedical research, with a mission to decode the mechanisms of ageing and how these contribute to age-related disease. Multiple hallmarks of ageing have been identified that are common across taxa, highlighting their fundamental importance. These include dysregulated mitochondrial metabolism and telomeres biology, epigenetic modifications, cell-matrix interactions, proteostasis, dysregulated nutrient sensing, stem cell exhaustion, inflammageing and immuno-senescence. While our understanding of the molecular basis of ageing is improving, it remains a complex and multifactorial process that remains to be fully understood. A key aspect of the shortfall in our understanding of the ageing process lies in translating data from standard animal models to humans. Consequently, we suggest that a 'biomimetic' and comparative approach, integrating knowledge from species in the wild, as opposed to inbred genetically homogenous laboratory animals, can provide powerful insights into human ageing processes. Here we discuss some particularities and comparative patterns among several species from the animal kingdom, endowed with longevity or short lifespans and unique metabolic profiles that could be potentially exploited to the understanding of ageing and age-related diseases. Based upon lessons from nature, we also highlight several avenues for renewed focus in the pathophysiology of ageing and age-related disease (i.e. diet-microbiome-health axis, oxidative protein damage, adaptive homoeostasis and planetary health). We propose that a biomimetic alliance with collaborative research from different disciplines can improve our understanding of ageing and age-related diseases with long-term sustainable utility.

Brain organoids: A promising model to assess oxidative stress-induced central nervous system damage

Oxidative stress (OS) is one of the most significant propagators of systemic damage with implications for widespread pathologies such as vascular disease, accelerated aging, degenerative disease, inflammation, and traumatic injury. OS can be induced by numerous factors such as environmental conditions, lifestyle choices, disease states, and genetic susceptibility. It is tied to the accumulation of free radicals, mitochondrial dysfunction, and insufficient antioxidant protection, which leads to cell aging and tissue degeneration over time. Unregulated systemic increase in reactive species, which contain harmful free radicals, can lead to diverse tissue-specific OS responses and disease. Studies of OS in the brain, for example, have demonstrated how this state contributes to neurodegeneration and altered neural plasticity. As the worldwide life expectancy has increased over the last few decades, the prevalence of OS-related diseases resulting from age-associated progressive tissue degeneration. Unfortunately, vital translational research studies designed to identify and target disease biomarkers in human patients have been impeded by many factors (e.g., limited access to human brain tissue for research purposes and poor translation of experimental models). In recent years, stem cell-derived three-dimensional tissue cultures known as "brain organoids" have taken the spotlight as a novel model for studying central nervous system (CNS) diseases. In this review, we discuss the potential of brain organoids to model the responses of human neural cells to OS, noting current and prospective limitations. Overall, brain organoids show promise as an innovative translational model to study CNS susceptibility to OS and elucidate the pathophysiology of the aging brain.

Mind the food: rapid changes in antioxidant content of diet affect oxidative status of chimpanzees

The link between dietary antioxidants and oxidative status has been studied extensively in humans. Surprisingly, comparative data are not available from closely related species, such as chimpanzees, which evolved in environments characterized by strong fluctuations in the availability and quality of vegetable food sources. We tested the hypothesis that an abrupt decrease in dietary antioxidants would increase oxidative damages in captive chimpanzees (Pan troglodytes), while a rapid increase in antioxidant intake would decrease oxidative damages accrued while on the low-antioxidant diet. An abrupt decline of dietary antioxidants increased urinary levels of lipid peroxides and of oxidative DNA damage but not of 8-isoprostanes. In contrast, an increased intake of dietary antioxidants did not affect the oxidative status. Chimpanzees that were both older and with a higher dominance rank had lower urinary levels of lipid peroxides and of DNA damage as compared with younger chimpanzees. Neither individual sex nor proportion of time being groomed explained any variation in all three markers of oxidative status. Finally, we found significant within-individual repeatability of all markers of oxidative status over the course of the experiment, suggesting a significant contribution of individual history to molding oxidative status. Our results show that antioxidant intake plays a nonnegligible role in the regulation of oxidative status homeostasis in our closest relatives, the chimpanzees. Our work also suggests that rapid short-term increases in antioxidant intake might not have the desired immediate impact on oxidative status, such as in the case of clinical interventions or training programs.

Stress and immunity in poultry: light management and nanotechnology as effective immune enhancers to fight stress

The poultry industry plays a significant role in boosting the economy of several countries, particularly developing countries, and acts as a good, cheap, and affordable source of animal protein. A stress-free environment is the main target in poultry production. There are several stressors, such as cold stress, heat stress, high stocking density, and diseases that can affect birds and cause several deleterious changes. Stress reduces feed intake and growth, as well as impairs immune response and function, resulting in high disease susceptibility. These effects are correlated with higher corticosteroid levels that modulate several immune pathways such as cytokine-cytokine receptor interaction and Toll-like receptor signaling along with induction of excessive production of reactive oxygen species (ROS) and thus oxidative stress. Several approaches have been considered to boost bird immunity to overcome stress-associated effects. Of these, dietary supplementation of certain nutrients and management modifications, such as light management, are commonly considered. Dietary supplementations improve bird immunity by improving the development of lymphoid tissues and triggering beneficial immune modulators and responses. Since nano-minerals have higher bioavailability compared to inorganic or organic forms, they are highly recommended to be included in the bird's diet during stress. Additionally, light management is considered a cheap and safe approach to control stress. Changing light from continuous to intermittent and using monochromatic light instead of the normal light improve bird performance and health. Such changes in light management are associated with a reduction of ROS production and increased antioxidant production. In this review, we discuss the impact of stress on the immune system of birds and the transcriptome of oxidative stress and immune-related genes, in addition, how nano-minerals supplementations and light system modulate or mitigate stress-associated effects.