Use of antioxidants and time of cold storage: effects over viability parameters and enzymatic levels in semen of rainbow trout (Oncorhynchus mykiss, Walbaum, 1792).

The cold storage of milt implies potentials alterations in its quality because the storage generates as main process, free radicals that produce spermatozoa membrane lipids damage with the consequent motility and fertilising capacity disruptions. To decrease the damage generated by free radicals the cells have antioxidant defences (proteins, enzymes, and low molecular weight substances). The objective of the present study evaluated the time storage effect and different antioxidants prepared in spermatic diluents on sperm viability of O. mykiss milt stored at 4°C. The two-way ANOVA denoted that the time storage and antioxidant influence have significant effects separated or combined on viability parameters (sperm motility and viability, proteins concentrations and superoxide dismutase enzymatic activity in seminal plasma). In contrast, only the storage time affected the fertilising capacity and catalase enzymatic activity in seminal plasma. The resulting analysis can conclude that the antioxidant presence improves the viability of cold stored milt, especially the transport conditions and the antioxidants allow the fecundity despite motility decrease.

The price of defence: toxins, visual signals and oxidative state in an aposematic butterfly

In a variety of aposematic species, the conspicuousness of an individual's warning signal and the quantity of its chemical defence are positively correlated. This apparent honest signalling in aposematism is predicted by resource competition models which assume that the production and maintenance of aposematic defences compete for access to antioxidant molecules that have dual functions as pigments directly responsible for colouration and in protecting against oxidative lipid damage. Here we study a model aposematic system - the monarch butterfly (Danaus plexippus) and make use of the variable phytochemistry of its larval host-plant, milkweeds (Asclepiadaceae), to manipulate the concentration of sequestered cardenolides. We test two fundamental assumptions of resource competition models: that (1) the possession of secondary defences is associated with costs in the form of oxidative lipid damage and reduced antioxidant defences; and (2) that oxidative damage or decreases in antioxidant defences can reduce the capacity of individuals to produce aposematic displays. Monarch caterpillars that sequestered the highest concentrations of cardenolides exhibited higher levels of oxidative lipid damage as adults. The relationship between warning signals, cardenolide concentrations and oxidative damage differed between the sexes. In male monarchs conspicuousness was explained by an interaction between oxidative damage and sequestration: as males sequester more cardenolides, those with high levels of oxidative damage become less conspicuous, while those that sequester lower levels of cardenolides equally invest in conspicuous with increasing oxidative damage. There was no significant effect of oxidative damage or concentration of sequestered cardenolides on female conspicuousness. Our results demonstrate physiological linkage between the production of coloration and protection from autotoxicity, that warning signals can be honest indicators of defensive capability, and that the relationships are different between the sexes.

Redox Systems, Oxidative Stress, and Antioxidant Defences in Health and Disease

Reactive oxygen and nitrogen species (RONS) play a key role in the regulation of cell survival [...]

Potassium Nitrate Treatment Is Associated with Modulation of Seed Water Uptake, Antioxidative Metabolism and Phytohormone Levels of Pea Seedlings

(1) Background: Seed treatment with potassium nitrate (KNO3) has been associated with dormancy breaking, improved germination and enhanced seedling growth and uniformity in a variety of plant species. However, the KNO3 effect seems to be dependent on plant species and treatment conditions. (2) Methods: We describe the effect of incubation of dry pea seeds with different KNO3 concentration on water uptake kinetic, early seedling growth, antioxidant metabolism and hormone profile in pea seedlings. (3) Results: Low (0.25 mM) KNO3 levels increased seedling water uptake and growth, whereas high (40 mM) levels decreased seedling growth. KNO3 treatment differentially affected the antioxidant defences. Low KNO3 levels maintained the activity of antioxidant enzymes, while high levels reduced the activity of H2O2-scavenging enzymes. KNO3 induced a progressive decline in ascorbate levels and reduced (GSH) and oxidised (GSSG) glutathione. Low KNO3 levels strongly increased GA1 and decreased ABA in both seedlings and cotyledons, resulting in a decline in the ABA/GAs ratio. (4) Conclusions: Pea seed treatment with a low KNO3 level promoted early seedling growth. In this process, an interaction among KNO3, antioxidant defences and ABA/GAs ratio is proposed.

Noscapine, an Emerging Medication for Different Diseases: A Mechanistic Review

Noscapine is a benzylisoquinoline alkaloid isolated from poppy extract, used as an antitussive since the 1950s, and has no addictive or euphoric effects. Various studies have shown that noscapine has excellent anti-inflammatory effects and potentiates the antioxidant defences by inhibiting nitric oxide (NO) metabolites and reactive oxygen species (ROS) levels and increasing total glutathione (GSH). Furthermore, noscapine has indicated antiangiogenic and antimetastatic effects. Noscapine induces apoptosis in many cancerous cell types and provides favourable antitumour activities and inhibitory cell proliferation in solid tumours, even drug-resistant strains, via mitochondrial pathways. Moreover, this compound attenuates the dynamic properties of microtubules and arrests the cell cycle in the G2/M phase. Noscapine can reduce endothelial cell migration in the brain by inhibiting endothelial cell activator interleukin 8 (IL-8). In fact, this study aimed to elaborate on the possible mechanisms of noscapine against different disorders.

Changes in the level of oxidative stress markers in Indian catfish (Wallago attu) infected with Isoparorchis hypselobagri

Background Helminth infection and infestation in fishes are detrimental and have a major effect on fish health and fish production. Among various factors, parasitic infections are known to modulate antioxidant defences in fish. Similar to other aerobic animals, fish are also susceptible to the effect of reactive oxygen species and thus have well established intrinsic and efficient antioxidant defences. ‘Oxidative stress markers are an important indicator of the physiological state of the parasite and its host’. Indian catfish, Wallago attu is a freshwater fish that serves as the definitive host of the adult piscine trematode Isoparorchis hypselobagri. Our two years prevalence data signifies the intensity of the problem revealing a minimum of 5.5% and a maximum of 54% I. hypselobagri infection in Indian catfish W. attu (unpublished data). The present study aimed to achieve baseline data attributed to changes in some oxidative markers due to parasitic infection. Results During the present study, the level of enzyme activities of Catalase (CAT), Glutathione reductase (GR), Glutathione-S-transferase (GST), Glutathione peroxidase (GPx), Superoxide dismutase (SOD) and lipid peroxidation was investigated to explore the pathogenic impact on the fish host. The level of these oxidative stress markers was monitored in the swim bladder, liver, intestine and muscle of the host. We also recorded the enzyme activities in the parasite I. hypselobagri. Analysis of data revealed an elevation in GST, SOD, GR, GPx and CAT activity in the infected host tissue as compared to the non-infected fish. Further, we observed presence of GST, SOD, GR and GPx enzymes in the parasite I. hypselobagri while CAT did not show any enzyme activity. Conclusions Increased level of enzyme activity in liver, muscle and intestine of infected host has been recorded which indicates increased oxidative stress in the host due to parasitic invasion. The presence of antioxidant enzymes in the parasites suggests an active antioxidant defence system to avoid immune responses to long term survival and establishment in their host.

Symbiont diversity and coral bleaching: An antioxidant view on thermal stress

<p>The functioning of coral reef systems, as biodiversity hotspots, is largely dependent on the symbiotic association between dinoflagellate symbionts (Symbiodinium spp.) and scleractinian coral hosts. The breakdown of this symbiosis (coral bleaching), as a result of global warming and other stressors, therefore has profound implications for the tropical marine environment. Corals associate with a variety of Symbiodinium genotypes, and it is this mosaic nature that contributes to the variable stress thresholds of corals. Research over the past 25 years has established that the generation and scavenging of reactive oxygen species (ROS) in both partners, under light and thermal stress, is a fundamental element of the bleaching response. However, while the existence of more thermally susceptible and tolerant symbiont types has been recognized, the differences in the antioxidant systems that may accompany these properties have received less attention. The purpose of this thesis was to explore the role of the antioxidant network in explaining the different thermal susceptibilities of various symbiont types and how the activity of key antioxidants in both partners under thermal stress relates to bleaching patterns in different corals. Thus, the specific objectives were to: (1) assess the antioxidant network response in different Symbiodinium types; (2) investigate the activity and structural diversity of key enzymatic antioxidants in different Symbiodinium types; (3) examine the regulation of these antioxidants at the transcriptomic and proteomic levels; and (4) contrast the symbiont’s and host’s antioxidant responses under bleaching conditions. Symbiodinium types in culture were found to differ significantly with regards to the concentration and activity of specific antioxidants, exhibiting magnitude scale differences in some of them. However, the response of the main removal pathway, involving superoxide dismutase (SOD) and ascorbate peroxidase (APX), under lethal thermal stress was fairly similar. Instead, the typespecific differences were found to lie in more downstream systems, and particularly in those associated with the maintenance of the glutathione redox state. A declining glutathione redox state was the common feature of the three thermally susceptible Symbiodinium types: B1, C1, and E. Indeed, in comparison to the most sensitive type (B1), the tolerant type F1 exhibited stronger antioxidant up-regulation and the successful preservation of the highly reduced glutathione pool. Comparing antioxidant gene orthologues from members of different Symbiodinium clades (A-E) revealed a higher degree of sequence variation at the amino acid level for peroxidases, which reflected the genetic radiation of the genus. In contrast, primary defences in the form of SOD isoforms were highly conserved. Sequence variations between Symbiodinium types involved residues that constitute binding sites of substrates and co-factors, and therefore likely affect the catalytic properties of these enzymes. While expression of antioxidant genes was successfully measured in Symbiodinium B1, it was not possible to assess the link between transcriptomic expression and proteomic activity due to high variability in expression between replicates, and little response in their enzymatic activity over three days. In contrast to previous findings, up-regulation of antioxidant defences was not evident in Symbiodinium cells inside the host (i.e. in hospite). In fact, oxidative stress in the thermally sensitive corals Acropora millepora and Pocillopora damicornis was only apparent from increased host catalase activity, which interestingly preceded photosynthetic dysfunction of their symbionts. Baseline antioxidant activities of thermally tolerant and susceptible host species showed no differences, though the scavenging activities of the hosts were considerably higher than those of the symbionts. Baseline activities for the symbionts were different, however, with Symbiodinium C15 from the thermally tolerant coral Montipora digitata exhibiting the lowest activities for SOD and catalase peroxidase. This thesis provides significant findings with respect to the variability in antioxidant activity, structure, and network response in different Symbiodinium types in culture, and how these relate to thermal tolerance. What effect these differences have on the response in the intact symbiosis remains unclear, however, as the findings contradict the classic bleaching model of photoinhibition and symbiont-derived ROS. I argue, using previously published data, that heating rates might profoundly affect the way we perceive the antioxidant response of both partners to thermal stress, and that host antioxidant defences might not be as easily overwhelmed by symbiont ROS as suggested previously. This thesis reports important findings on the antioxidant system in different Symbiodinium types, but also raises new questions about the antioxidant response of the intact coral.</p>

Symbiont diversity and coral bleaching: An antioxidant view on thermal stress

<p>The functioning of coral reef systems, as biodiversity hotspots, is largely dependent on the symbiotic association between dinoflagellate symbionts (Symbiodinium spp.) and scleractinian coral hosts. The breakdown of this symbiosis (coral bleaching), as a result of global warming and other stressors, therefore has profound implications for the tropical marine environment. Corals associate with a variety of Symbiodinium genotypes, and it is this mosaic nature that contributes to the variable stress thresholds of corals. Research over the past 25 years has established that the generation and scavenging of reactive oxygen species (ROS) in both partners, under light and thermal stress, is a fundamental element of the bleaching response. However, while the existence of more thermally susceptible and tolerant symbiont types has been recognized, the differences in the antioxidant systems that may accompany these properties have received less attention. The purpose of this thesis was to explore the role of the antioxidant network in explaining the different thermal susceptibilities of various symbiont types and how the activity of key antioxidants in both partners under thermal stress relates to bleaching patterns in different corals. Thus, the specific objectives were to: (1) assess the antioxidant network response in different Symbiodinium types; (2) investigate the activity and structural diversity of key enzymatic antioxidants in different Symbiodinium types; (3) examine the regulation of these antioxidants at the transcriptomic and proteomic levels; and (4) contrast the symbiont’s and host’s antioxidant responses under bleaching conditions. Symbiodinium types in culture were found to differ significantly with regards to the concentration and activity of specific antioxidants, exhibiting magnitude scale differences in some of them. However, the response of the main removal pathway, involving superoxide dismutase (SOD) and ascorbate peroxidase (APX), under lethal thermal stress was fairly similar. Instead, the typespecific differences were found to lie in more downstream systems, and particularly in those associated with the maintenance of the glutathione redox state. A declining glutathione redox state was the common feature of the three thermally susceptible Symbiodinium types: B1, C1, and E. Indeed, in comparison to the most sensitive type (B1), the tolerant type F1 exhibited stronger antioxidant up-regulation and the successful preservation of the highly reduced glutathione pool. Comparing antioxidant gene orthologues from members of different Symbiodinium clades (A-E) revealed a higher degree of sequence variation at the amino acid level for peroxidases, which reflected the genetic radiation of the genus. In contrast, primary defences in the form of SOD isoforms were highly conserved. Sequence variations between Symbiodinium types involved residues that constitute binding sites of substrates and co-factors, and therefore likely affect the catalytic properties of these enzymes. While expression of antioxidant genes was successfully measured in Symbiodinium B1, it was not possible to assess the link between transcriptomic expression and proteomic activity due to high variability in expression between replicates, and little response in their enzymatic activity over three days. In contrast to previous findings, up-regulation of antioxidant defences was not evident in Symbiodinium cells inside the host (i.e. in hospite). In fact, oxidative stress in the thermally sensitive corals Acropora millepora and Pocillopora damicornis was only apparent from increased host catalase activity, which interestingly preceded photosynthetic dysfunction of their symbionts. Baseline antioxidant activities of thermally tolerant and susceptible host species showed no differences, though the scavenging activities of the hosts were considerably higher than those of the symbionts. Baseline activities for the symbionts were different, however, with Symbiodinium C15 from the thermally tolerant coral Montipora digitata exhibiting the lowest activities for SOD and catalase peroxidase. This thesis provides significant findings with respect to the variability in antioxidant activity, structure, and network response in different Symbiodinium types in culture, and how these relate to thermal tolerance. What effect these differences have on the response in the intact symbiosis remains unclear, however, as the findings contradict the classic bleaching model of photoinhibition and symbiont-derived ROS. I argue, using previously published data, that heating rates might profoundly affect the way we perceive the antioxidant response of both partners to thermal stress, and that host antioxidant defences might not be as easily overwhelmed by symbiont ROS as suggested previously. This thesis reports important findings on the antioxidant system in different Symbiodinium types, but also raises new questions about the antioxidant response of the intact coral.</p>

Pomacea canaliculata Ampullar Proteome: A Nematode-Based Bio-Pesticide Induces Changes in Metabolic and Stress-Related Pathways

Pomacea canaliculata is a freshwater gastropod known for being both a highly invasive species and one of the possible intermediate hosts of the mammalian parasite Angiostrongylus cantonensis. With the aim of providing new information concerning P. canaliculata biology and adaptability, the first proteome of the ampulla, i.e., a small organ associated with the circulatory system and known as a reservoir of nitrogen-containing compounds, was obtained. The ampullar proteome was derived from ampullae of control snails or after exposure to a nematode-based molluscicide, known for killing snails in a dose- and temperature-dependent fashion. Proteome analysis revealed that the composition of connective ampulla walls, cell metabolism and oxidative stress response were affected by the bio-pesticide. Ultrastructural investigations have highlighted the presence of rhogocytes within the ampullar walls, as it has been reported for other organs containing nitrogen storage tissue. Collected data suggested that the ampulla may belong to a network of organs involved in controlling and facing oxidative stress in different situations. The response against the nematode-based molluscicide recalled the response set up during early arousal after aestivation and hibernation, thus encouraging the hypothesis that metabolic pathways and antioxidant defences promoting amphibiousness could also prove useful in facing other challenges stimulating an oxidative stress response, e.g., immune challenges or biocide exposure. Targeting the oxidative stress resistance of P. canaliculata may prove helpful for increasing its susceptibility to bio-pesticides and may help the sustainable control of this pest’s diffusion.

TNFα SIGNALLING IN THE CUTANEOUS IMMUNE NETWORK INSTRUCTS LOCAL Th17 ALLERGEN-SPECIFIC INFLAMMATORY RESPONSES IN ATOPIC DERMATITIS

Accurate regulation of cutaneous immunity is fundamental for human health and quality of life but is severely compromised in inflammatory skin disease. To investigate the molecular crosstalk underpinning tolerance vs inflammation in human skin, we set up a human in vivo allergen challenge study, exposing patients with atopic dermatitis (AD) to house dust mite (HDM). Analyses of transcriptional programmes at the population and single cell levels in parallel with immunophenotyping of resident and infiltrating immune cells indicated that inflammatory responses to HDM were associated with immune activation in Langerhans cells (LCs) and cutaneous T cells. High basal level of TNFα production by cutaneous Th17 T cells predisposed to an inflammatory reaction and resulted in formation of hub structures where LCs and T cells interacted, leading to loss of functional programming in LCs. Additionally, single nucleotide polymorphisms in MT1X gene associated with enhanced expression of metallothioneins and transcriptional programmes encoding antioxidant defences across skin cell types in non-reactive patients, were protective against T cell mediated inflammation. Our results provide a unique insight into the dynamics of immune regulation in the human skin and define regulatory circuits that can be harnessed to improve skin health and treat disease.