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1.
PLoS Comput Biol ; 16(9): e1008202, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32925922

RESUMO

Hydrogen peroxide (H2O2) promotes a range of phenotypes depending on its intracellular concentration and dosing kinetics, including cell death. While this qualitative relationship has been well established, the quantitative and mechanistic aspects of H2O2 signaling are still being elucidated. Mitochondria, a putative source of intracellular H2O2, have recently been demonstrated to be particularly vulnerable to localized H2O2 perturbations, eliciting a dramatic cell death response in comparison to similar cytosolic perturbations. We sought to improve our dynamic and mechanistic understanding of the mitochondrial H2O2 reaction network in HeLa cells by creating a kinetic model of this system and using it to explore basal and perturbed conditions. The model uses the most current quantitative proteomic and kinetic data available to predict reaction rates and steady-state concentrations of H2O2 and its reaction partners within individual mitochondria. Time scales ranging from milliseconds to one hour were simulated. We predict that basal, steady-state mitochondrial H2O2 will be in the low nM range (2-4 nM) and will be inversely dependent on the total pool of peroxiredoxin-3 (Prx3). Neglecting efflux of H2O2 to the cytosol, the mitochondrial reaction network is expected to control perturbations well up to H2O2 generation rates ~50 µM/s (0.25 nmol/mg-protein/s), above which point the Prx3 system would be expected to collapse. Comparison of these results with redox Western blots of Prx3 and Prx2 oxidation states demonstrated reasonable trend agreement at short times (≤ 15 min) for a range of experimentally perturbed H2O2 generation rates. At longer times, substantial efflux of H2O2 from the mitochondria to the cytosol was evidenced by peroxiredoxin-2 (Prx2) oxidation, and Prx3 collapse was not observed. A refined model using Monte Carlo parameter sampling was used to explore rates of H2O2 efflux that could reconcile model predictions of Prx3 oxidation states with the experimental observations.


Assuntos
Peróxido de Hidrogênio/metabolismo , Mitocôndrias/metabolismo , Modelos Biológicos , Neoplasias/metabolismo , Biologia Computacional , Citosol/química , Citosol/metabolismo , Células HeLa , Humanos , Cinética , Mitocôndrias/química , Neoplasias/química , Espécies Reativas de Oxigênio/química , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/fisiologia
2.
Ecotoxicol Environ Saf ; 203: 111025, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888593

RESUMO

We investigated individual and combined effects of environmentally representative concentrations of amoxicillin (AMX; 2 µg l-1), enrofloxacin (ENR; 2 µg l-1), and oxytetracycline (OXY; 1 µg l-1) on the aquatic macrophyte Lemna minor. While the concentrations of AMX and ENR tested were not toxic, OXY decreased plant growth and cell division. OXY induced hydrogen peroxide (H2O2) accumulation and related oxidative stress through its interference with the activities of mitochondria electron transport chain enzymes, although those deleterious effects could be ameliorated by the presence of AMX and/or ENR, which prevented the overaccumulation of ROS by increasing catalase enzyme activity. L. minor plants accumulated significant quantities of AMX, ENR and OXY from the media, although competitive uptakes were observed when plants were submitted to binary or tertiary mixtures of those antibiotics. Our results therefore indicate L. minor as a candidate for phytoremediation of service waters contaminated by AMX, ENR, and/or OXY.


Assuntos
Amoxicilina/toxicidade , Araceae/efeitos dos fármacos , Enrofloxacina/toxicidade , Oxitetraciclina/toxicidade , Fotossíntese/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Amoxicilina/análise , Amoxicilina/metabolismo , Araceae/crescimento & desenvolvimento , Araceae/metabolismo , Biodegradação Ambiental , Catalase/metabolismo , Relação Dose-Resposta a Droga , Interações Medicamentosas , Enrofloxacina/análise , Enrofloxacina/metabolismo , Peróxido de Hidrogênio/metabolismo , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Oxitetraciclina/análise , Oxitetraciclina/metabolismo , Poluentes Químicos da Água/análise
3.
Ecotoxicol Environ Saf ; 205: 111350, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32961487

RESUMO

Atmospheric nitrogen dioxide (NO2) negatively affects plant (crop) growth and development, as well the yield and quality in some regions or environments. Arbuscular mycorrhizal fungus (AMF)-mediated amelioration of NO2-induced plant damage has been reported, but the underlying mechanisms remained unclear. This study explored the beneficial effect of AMF symbiosis on tomato plant responses to NO2 at physiology, biochemistry, and gene expression, with an emphasis on nitrate metabolism, antioxidative defense, and photosynthetic performance. Pot-grown plants were used in the experiments, which were performed in laboratory from February to November 2019. NO2 fumigation with a dose of 10 ± 1 ppm was carried out after 50 d of plant growth, and data were collected following 8 h of fumigation. NO2 fumigation (+NO2) and AMF inoculation (+AMF), alone and especially in combination (NO2 + AMF), increased the gene expression of nitrate- and nitrite reductase, and their enzymatic activity in leaves, such as by 61%, 27%, and 126% for the activity of nitrate reductase, and by 95%, 37%, and 188% for nitrite reductase, respectively, in +NO2, +AMF, and AMF + NO2 plants relative the control (-NO2, -AMF) levels. Following NO2 exposure, +AMF leaves displayed stronger activities of superoxide dismutase, peroxidase and catalase, and higher content of glutathione and ratio of its reduced form to oxidized form, as compared with -AMF ones. Correspondingly, lesser oxidative damage was detected in +AMF than in -AMF plants, as indicated by the contents of H2O2 and malondialdehyde, electrolyte leakage, also by in situ visualization for the formation of H2O2, superoxide anion, and dead cells. The increased antioxidative capacity in +AMF plants was correlated with enhanced expression of antioxidation-related genes. Exposure to NO2 substantially impaired photosynthetic processes in both + AMF and -AMF plants, but an obvious mitigation was observed in the former than in the latter. For example, the total chlorophyll, net photosynthetic rate, stomatal conductance, and ribulose-1,5-bisphosphate carboxylase activity were 18%, 27%, 26%, and 40% higher, respectively, in +AMF than in -AMF plants under NO2 stress. The differential photosynthetic performance was also revealed by chlorophyll fluorescence imaging. We analyzed the expression patterns of some genes related to photosynthesis and carbon metabolisms, and found that all of them exclusively presented a higher expression level in +AMF plants relative to -AMF ones under NO2 stress. Taken together, this study provided evidence that AMF symbiosis played a positively regulatory role in host plant responses to NO2, probably by increasing leaf nitrate metabolism and antioxidative defense, and maintaining the photosynthetic efficiency to some extent, wherein the transcription regulation might be a main target.


Assuntos
Lycopersicon esculentum/fisiologia , Micorrizas/fisiologia , Dióxido de Nitrogênio/toxicidade , Antioxidantes/metabolismo , Clorofila/metabolismo , Peróxido de Hidrogênio/metabolismo , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/microbiologia , Micorrizas/metabolismo , Oxirredução , Fotossíntese/fisiologia , Desenvolvimento Vegetal , Folhas de Planta/metabolismo
4.
Ecotoxicol Environ Saf ; 203: 110974, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888622

RESUMO

Ammonia (NH3), an environmental pollutant, poses a serious threat to human and avian health. Although previous studies have showed that NH3 caused kidney injury, the molecular mechanisms of nephrotoxicity induced by NH3 remain unclear. To explore the mechanisms of NH3 nephrotoxicity, a total of 36 broiler chicks at one day of age were exposed to NH3. After 42 days of exposure, blood samples were collected to determine creatinine and uric acid; and kidney samples were weighted and then collected to detect ultrastructural changes, oxidative stress parameters, ATPases, necroptosis- and mitochondrial dynamics-related genes. The results showed that chickens exposed to NH3 showed lower relative kidney weight and an increase concentration in serum creatinine and uric acid. NH3 exposure caused nephrocyte necrosis and increased the expression of necroptosis-related genes (TNF-α, RIPK1, RIPK3, MLKL, and JNK). Besides, the activities of antioxidant systems (SOD, CAT, GSH-Px, and T-AOC) were reduced, whereas the concentrations of H2O2 and MDA were elevated. Lower activities of ATPases were obtained in NH3 treatment groups. Furthermore, the mitochondrial fission-related genes drp1 and mff were activated, and mitochondrial fusion-related genes opa1, mfn1 and mfn2 were suppressed after NH3 exposure. Based on the above results, we conclude that NH3 caused-oxidative stress and mitochondrial dysfunction mediated nephrocyte necroptosis in chickens. This study may provide new insight into NH3 nephrotoxicity.


Assuntos
Amônia/toxicidade , Poluentes Ambientais/toxicidade , Rim/efeitos dos fármacos , Dinâmica Mitocondrial/efeitos dos fármacos , Necroptose/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Animais , Antioxidantes/metabolismo , Galinhas , Expressão Gênica/efeitos dos fármacos , Humanos , Peróxido de Hidrogênio/metabolismo , Rim/ultraestrutura , Testes de Função Renal , Dinâmica Mitocondrial/genética , Tamanho do Órgão/efeitos dos fármacos , Estresse Oxidativo/genética , Proteína Serina-Treonina Quinases de Interação com Receptores/genética
5.
Nat Commun ; 11(1): 4512, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32908147

RESUMO

Hydrogen peroxide (H2O2) is recognized to act as a signaling molecule. Peroxiredoxins (Prxs) have the ability to transfer H2O2-derived oxidizing equivalents to redox-regulated target proteins, thus facilitating the transmission of H2O2 signals. It has remained unclear how Prxs and their target proteins are brought together to allow for target-specific protein thiol oxidation. Addressing the specific case of Prx2-dependent STAT3 oxidation, we here show that the association of the two proteins occurs prior to Prx oxidation and depends on a scaffolding protein, the membrane chaperone annexin A2. Deletion or depletion of annexin A2 interrupts the transfer of oxidizing equivalents from Prx2 to STAT3, which is observed to take place on membranes. These findings support the notion that the Prx2-STAT3 redox relay is part of a highly organized membrane signaling domain.


Assuntos
Anexina A2/metabolismo , Peroxirredoxinas/metabolismo , Fator de Transcrição STAT3/metabolismo , Anexina A2/genética , Linhagem Celular Tumoral , Membrana Celular/metabolismo , Dissulfetos/metabolismo , Células HEK293 , Humanos , Peróxido de Hidrogênio/metabolismo , Oxirredução , Ligação Proteica , Domínios Proteicos , Transdução de Sinais
6.
Chemosphere ; 258: 127411, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32947668

RESUMO

Non-steroidal anti-inflammatory drugs as an important group of emerging environmental contaminants in irrigation water and soils can influence biochemical and physiological processes essential for growth and development in plants as non-target organisms. Plants are able to take up, transport, transform, and accumulate drugs in the roots. Root biomass in ten-days old pea plants was lowered by 6% already under 0.1 mg/L naproxen (NPX) due to a lowered number of lateral roots, although 0.5 mg/L NPX stimulated the total root length by 30% as against control. Higher section area (by 40%) in root tip, area of xylem (by 150%) or stele-to-section ratio (by 10%) in zone of maturation, and lower section area in zone of lateral roots (by 18%) prove the changes in primary root anatomy and its earlier differentiation at 10 mg/L NPX. Accumulated NPX (up to 10 µg/g DW at 10 mg/L) and products of its metabolization in roots increased the amounts of hydrogen peroxide (by 33%), and superoxide (by 62%), which was reflected in elevated lipid peroxidation (by 32%), disruption of membrane integrity (by 89%) and lowering both oxidoreductase and dehydrogenase activities (by up to 40%). Elevated antioxidant capacity (SOD, APX, and other molecules) under low treatments decreased at 10 mg/L NPX (both by approx. 30%). Naproxen was proved to cause changes at both cellular and tissue levels in roots, which was also reflected in their anatomy and morphology. Higher environmental loading through drugs thus can influence even the root function.


Assuntos
Anti-Inflamatórios não Esteroides/toxicidade , Naproxeno/toxicidade , Ervilhas/fisiologia , Antioxidantes/metabolismo , Peróxido de Hidrogênio/metabolismo , Peroxidação de Lipídeos , Estresse Oxidativo/efeitos dos fármacos , Ervilhas/efeitos dos fármacos , Raízes de Plantas
7.
Ecotoxicol Environ Saf ; 205: 111293, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32949840

RESUMO

Wastewater from printing and dyeing processes often contains aniline and high salinity, which are hazardous to aquatic species. Glycophytic plants cannot survive under high-salinity conditions, whereas halophytes grow well in such an environment. In this study, we investigated the influence of NaCl on the antioxidant level in Suaeda salsa affected by aniline stress. The seedlings showed various growth toxicity effects under different concentrations of aniline. The results showed that the effect of the aniline was more severe for the root growth compared to that for the shoot growth. Aniline exposure significantly increased the total free radicals and ·OH radicals in the plants. Suaeda salsa exposure to aniline caused oxidative stress by altering the superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activity, which resulted in the overproduction of H2O2 and the inducement of lipid peroxidation. Analysis revealed that the malondialdehyde (MDA) content was enhanced after aniline exposure and that the chlorophyll content was significantly decreased. The results showed that aniline induced the production of free radicals and reactive oxygen species (ROS), and changed the antioxidant defense system. This ultimately resulted in oxidative damage in S. salsa; however, it was found that moderate salinity could mitigate the effects. In conclusion, salinity may alleviate the growth inhibition caused by aniline by regulating the antioxidant capacity of S. salsa.


Assuntos
Compostos de Anilina/toxicidade , Antioxidantes/metabolismo , Chenopodiaceae/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Cloreto de Sódio/farmacologia , Poluentes Químicos da Água/toxicidade , Catalase/metabolismo , Chenopodiaceae/enzimologia , Chenopodiaceae/crescimento & desenvolvimento , Clorofila/metabolismo , Espectroscopia de Ressonância de Spin Eletrônica , Peróxido de Hidrogênio/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Malondialdeído/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Salinidade , Plantas Tolerantes a Sal/efeitos dos fármacos , Plantas Tolerantes a Sal/enzimologia , Plantas Tolerantes a Sal/crescimento & desenvolvimento , Plântula/efeitos dos fármacos , Plântula/enzimologia , Plântula/crescimento & desenvolvimento , Superóxido Dismutase/metabolismo
8.
Ecotoxicol Environ Saf ; 202: 110916, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800251

RESUMO

Selenium (Se) at low concentration is considered benefit element to plants. The range between optimal and toxic concentration of Se is narrow and varies among plant species. This study aimed to evaluate the phenotypic, physiological and biochemical responses of four rice genotypes (BRS Esmeralda, BRSMG Relâmpago, BRS Bonança and Bico Ganga) grown hydroponically treated with sodium selenate (1.5 mM L-1). Selenium treated plants showed a dramatically decrease of soluble proteins, chlorophylls, and carotenoids concentration, resulting in the visual symptoms of toxicity characterized as leaf chlorosis and necrosis. Selenium toxicity caused a decrease on shoot and root dry weight of rice plants. Excess Se increased the oxidative stress monitored by the levels of hydrogen peroxide and lipid peroxidation. The enzymatic antioxidant system (catalase, superoxide dismutase, and ascorbate peroxidase) increased in response to Se supply. Interestingly, primary metabolism compounds such as sucrose, total sugars, nitrate, ammonia and amino acids increased in Se-treated plants. The increase in these metabolites may indicate a defense mechanism for the osmotic readjustment of rice plants to mitigate the toxicity caused by Se. However, these metabolites were not effective to minimize the damages on phenotypic traits such as leaf chlorosis and reduced shoot and root dry weight in response to excess Se. Increased sugars profile combined with antioxidant enzymes activities can be an effective biomarkers to indicate stress induced by Se in rice plants. This study shows the physiological attributes that must be taken into account for success in the sustainable cultivation of rice in environments containing excess Se.


Assuntos
Oryza/fisiologia , Selênio/toxicidade , Poluentes do Solo/toxicidade , Antioxidantes/metabolismo , Ascorbato Peroxidases/metabolismo , Catalase/metabolismo , Clorofila/metabolismo , Peróxido de Hidrogênio/metabolismo , Hidroponia , Peroxidação de Lipídeos , Oryza/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Folhas de Planta/metabolismo , Ácido Selênico/metabolismo , Superóxido Dismutase/metabolismo
9.
Ecotoxicol Environ Saf ; 205: 111167, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32827967

RESUMO

Contamination of agricultural fields with Cadmium (Cd) due to several agricultural practices is increasing worldwide. The rice plants can easily take up Cd and accumulate it into different parts, including the grains, posing a threat to human health even at low concentration exposure. Several phytohormones, including Salicylic acid (SA) have been investigated since long for its alleviating properties under various biotic and abiotic stress conditions. In the present study, 100 µM SA application to ameliorate 25 µM Cd stress was studied for 72 h in hydroponics in Oryza sativa cv. Bandana seedlings. Pot experiments were done with same treatment condition and plants were grown till maturity. SA application to Cd exposed rice seedlings alleviated the stress condition, which was established by several physiological, biochemical, histochemical and gene expression analysis. SA treatment to Cd stressed seedlings showed elevated photosynthetic pigment content, on-protein thiol content and relieved the Cd induced growth inhibition considerably. It lowered the accumulation of ROS like, O2- and H2O2 with a regulated antioxidative enzymatic activity. SA application in Cd exposed rice seedlings had upregulated expression of OsHMA3 and OsPCS1 whereasOsNRAMP2 gene was downregulated. Co-application of SA and Cd led to higher yield and improved agronomic traits in comparison to only Cd exposed plants under pot experimentation. Daily intake of Cd and Carcinogenic risk were also reduced by 99.75% and 99.99% respectively in the SA treated Cd stressed plants. SA positively affected the growth and tolerance of rice seedlings to Cd stress. Hence, SA addition to Cd contaminated soil can ensure rice cultivation without posing health risk to consumers.


Assuntos
Bioacumulação/efeitos dos fármacos , Cádmio/toxicidade , Grão Comestível/efeitos dos fármacos , Oryza/efeitos dos fármacos , Ácido Salicílico/farmacologia , Poluentes do Solo/toxicidade , Antioxidantes/metabolismo , Cádmio/metabolismo , Grão Comestível/metabolismo , Peróxido de Hidrogênio/metabolismo , Hidroponia , Oryza/metabolismo , Fotossíntese/efeitos dos fármacos , Plântula/efeitos dos fármacos , Plântula/metabolismo , Poluentes do Solo/metabolismo , Estresse Fisiológico/efeitos dos fármacos
10.
Ecotoxicol Environ Saf ; 205: 111186, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32853868

RESUMO

Exposure to ambient air particulate matter (PM) is associated with increased cardiorespiratory morbidity and mortality. In this context, alveolar macrophages exhibit proinflammatory and oxidative responses as a result of the clearance of particles, thus contributing to lung injury. However, the mechanisms linking these pathways are not completely clarified. Therefore, the oxinflammation phenomenon was studied in RAW 264.7 macrophages exposed to Residual Oil Fly Ash (ROFA), a PM surrogate rich in transition metals. While cell viability was not compromised under the experimental conditions, a proinflammatory phenotype was observed in cells incubated with ROFA 100 µg/mL, characterized by increased levels of TNF-α and NO production, together with PM uptake. This inflammatory response seems to precede alterations in redox metabolism, characterized by augmented levels of H2O2, diminished GSH/GSSG ratio, and increased SOD activity. This scenario resulted in increased oxidative damage to phospholipids. Moreover, alterations in mitochondrial respiration were observed following ROFA incubation, such as diminished coupling efficiency and spare respiratory capacity, together with augmented proton leak. These findings were accompanied by a decrease in mitochondrial membrane potential. Finally, NADPH oxidase (NOX) and mitochondria were identified as the main sources of superoxide anion () in our model. These results indicate that PM exposure induces direct activation of macrophages, leading to inflammation and increased reactive oxygen species production through NOX and mitochondria, which impairs antioxidant defense and may cause mitochondrial dysfunction.


Assuntos
Macrófagos Alveolares/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , NADPH Oxidases/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Material Particulado/toxicidade , Superóxidos/metabolismo , Poluentes Atmosféricos/toxicidade , Animais , Antioxidantes/metabolismo , Cinza de Carvão/toxicidade , Peróxido de Hidrogênio/metabolismo , Inflamação , Macrófagos Alveolares/imunologia , Macrófagos Alveolares/metabolismo , Camundongos , Mitocôndrias/imunologia , Mitocôndrias/metabolismo , Oxirredução , Estresse Oxidativo/imunologia , Células RAW 264.7 , Fator de Necrose Tumoral alfa/metabolismo
11.
Chemosphere ; 255: 127041, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32679635

RESUMO

Microplastics pollution in farmlands has become a major concern. However, few studies have assessed the effects of microplastics on higher plants. In this study, we investigated the influence of polystyrene nanoplastics (PSNPs, 50 mg L-1), with four different particle sizes (100, 300, 500, and 700 nm), on the physiological and biochemical indexes of cucumber leaves. The biomass of cucumber plants significantly decreased after exposure to 300 nm PSNPs. Similarly, the chlorophyll a, chlorophyll b, soluble sugar, carotenoid, and proline content, as well as the fluorescence of cucumber leaves were significantly reduced by 100 nm PSNPs. Malondialdehyde, proline, peroxidase gene expression and enzyme activity, and hydrogen peroxide content significantly increased in cucumber leaves exposed to 700 nm PSNPs. In addition, increasing PSNPs particle size led to decreased relative expression levels and activities of the major antioxidant enzymes superoxide dismutase and catalase, while vitamin C and soluble protein content significantly increased. Overall, our results indicated that PSNPs affect the photosynthetic, antioxidant, and sugar metabolism systems of cucumber leaves, with the latter clearly affecting the total biomass of cucumber plants. The benzene ring resulting from the degradation of PSNPs in cucumber leaves may be the main factor affecting chlorophyll metabolism and sugar metabolism. Our findings provide a scientific basis for the risk assessment of PSNPs exposure in soil-plant systems.


Assuntos
Cucumis sativus/fisiologia , Poliestirenos/toxicidade , Poluentes do Solo/toxicidade , Antioxidantes/metabolismo , Carotenoides/metabolismo , Catalase/metabolismo , Clorofila , Clorofila A , Cucumis sativus/efeitos dos fármacos , Peróxido de Hidrogênio/metabolismo , Malondialdeído/metabolismo , Peroxidases/metabolismo , Fotossíntese/efeitos dos fármacos , Folhas de Planta/metabolismo , Plásticos/metabolismo , Poliestirenos/metabolismo , Superóxido Dismutase/metabolismo
12.
Food Chem ; 332: 127229, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32688187

RESUMO

Hydrogen peroxide plays a key role in honey antibacterial activity. The production of H2O2 in honey requires glucose oxidase (GOx) that oxidizes glucose to gluconolactone and reduces molecular oxygen to hydrogen peroxide. The content of GOx of honeybee origin was believed to be the main predictor of H2O2 concentration in honey. The observed variations in H2O2 levels among honeys questioned however the direct GOx-H2O2 relationship and left its absence opened for exploration. Here, we evaluated principal causes underlying the imbalance in the quantitative enzyme-product relationship with respect to: (a) enzyme and the product inactivation or destruction by honey compounds; (b) non-enzymatic pathway of H2O2 formation, and (c) a potential contribution of enzymes with GOx activity originating from nectars and microorganisms inhabiting honey. We also bring new facts on the relationship between honey colloidal structure and H2O2 production that change our traditional understanding of honey function as antimicrobial agent.


Assuntos
Mel , Peróxido de Hidrogênio/metabolismo , Antibacterianos/metabolismo , Glucose Oxidase/metabolismo
13.
Chemosphere ; 259: 127410, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32615455

RESUMO

Arsenic (As) can be present naturally in groundwater from peanut fields, constituting a serious problem, as roots can accumulate and mobilize the metalloid to their edible parts. Understanding the redox changes in the legume exposed to As may help to detect potential risks to human health and recognize tolerance mechanisms. Thirty-days old peanut plants inoculated with Bradyrhizobium sp. strains (SEMIA6144 or C-145) were exposed to a realistic arsenate concentration, in order to unravel the redox response and characterize the oxidative stress indexes. Thus, root anatomy, reactive oxygen species detection by fluorescence microscopy and, ROS histochemical staining along with the NADPH oxidase activity were analyzed. Besides, photosynthetic pigments and damage to lipids and proteins were determined as oxidative stress indicators. Results showed that at 3 µM AsV, the cross-section areas of peanut roots were augmented; NADPH oxidase activity was significantly increased and O2˙¯and H2O2 accumulated in leaves and roots. Likewise, an increase in the lipid peroxidation and protein carbonyls was also observed throughout the plant regardless the inoculated strain, while chlorophylls and carotenes were increased only in those inoculated with Bradyrhizobium sp. C-145. Interestingly, the oxidative burst, mainly induced by the NADPH oxidase activity, and the consequent oxidative stress was strain-dependent and organ-differential. Additionally, As modifies the root anatomy, acting as a possibly first defense mechanism against the metalloid entry. All these findings allowed us to conclude that the redox response of peanut is conditioned by the rhizobial strain, which contributes to the importance of effectively formulating bioinoculants for this crop.


Assuntos
Arachis/microbiologia , Arsênico/toxicidade , Bradyrhizobium/fisiologia , Estresse Oxidativo/fisiologia , Arachis/efeitos dos fármacos , Arachis/metabolismo , Arachis/fisiologia , Arseniatos , Arsênico/metabolismo , Bradyrhizobium/efeitos dos fármacos , Bradyrhizobium/metabolismo , Clorofila/metabolismo , Peróxido de Hidrogênio/metabolismo , Peroxidação de Lipídeos , Oxirredução , Raízes de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Simbiose/efeitos dos fármacos
14.
Proc Natl Acad Sci U S A ; 117(28): 16313-16323, 2020 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-32601209

RESUMO

Peroxiredoxins are central to cellular redox homeostasis and signaling. They serve as peroxide scavengers, sensors, signal transducers, and chaperones, depending on conditions and context. Typical 2-Cys peroxiredoxins are known to switch between different oligomeric states, depending on redox state, pH, posttranslational modifications, and other factors. Quaternary states and their changes are closely connected to peroxiredoxin activity and function but so far have been studied, almost exclusively, outside the context of the living cell. Here we introduce the use of homo-FRET (Förster resonance energy transfer between identical fluorophores) fluorescence polarization to monitor dynamic changes in peroxiredoxin quaternary structure inside the crowded environment of living cells. Using the approach, we confirm peroxide- and thioredoxin-related quaternary transitions to take place in cellulo and observe that the relationship between dimer-decamer transitions and intersubunit disulfide bond formation is more complex than previously thought. Furthermore, we demonstrate the use of the approach to compare different peroxiredoxin isoforms and to identify mutations and small molecules affecting the oligomeric state inside cells. Mutagenesis experiments reveal that the dimer-decamer equilibrium is delicately balanced and can be shifted by single-atom structural changes. We show how to use this insight to improve the design of peroxiredoxin-based redox biosensors.


Assuntos
Peroxirredoxinas/química , Linhagem Celular , Transferência Ressonante de Energia de Fluorescência , Proteínas de Homeodomínio/química , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Humanos , Peróxido de Hidrogênio/metabolismo , Peróxido de Hidrogênio/farmacologia , Proteínas Luminescentes/química , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Mutação , Peroxirredoxinas/genética , Peroxirredoxinas/metabolismo , Multimerização Proteica/efeitos dos fármacos , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo
15.
PLoS One ; 15(7): e0235975, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32649704

RESUMO

Rice cultivar "Weiyou916" (Oryza sativa L. ssp. Indica) were cultured with control (10 mM NO3-) and nitrate deficient solution (0 mM NO3-) for four weeks. Nitrogen (N) deficiency significantly decreased the content of N and P, dry weight (DW) of the shoots and roots, but increased the ratio of root to shoot in O. sativa. N deficiency decreased the photosynthesis rate and the maximum quantum yield of primary photochemistry (Fv/Fm), however, increased the intercellular CO2 concentration and primary fluorescence (Fo). N deficiency significantly increased the production of H2O2 and membrane lipid peroxidation revealed as increased MDA content in O. sativa leaves. N deficiency significantly increased the contents of starch, sucrose, fructose, and malate, but did not change that of glucose and total soluble protein in O. sativa leaves. The accumulated carbohydrates and H2O2 might further accelerate biosynthesis of lignin in O. sativa leaves under N limitation. A total of 1635 genes showed differential expression in response to N deficiency revealed by Illumina sequencing. Gene Ontology (GO) analysis showed that 195 DEGs were found to highly enrich in nine GO terms. Most of DEGs involved in photosynthesis, biosynthesis of ethylene and gibberellins were downregulated, whereas most of DEGs involved in cellular transport, lignin biosynthesis and flavonoid metabolism were upregulated by N deficiency in O. sativa leaves. Results of real-time quantitative PCR (RT-qPCR) further verified the RNA-Seq data. For the first time, DEGs involved oxygen-evolving complex, phosphorus response and lignin biosynthesis were identified in rice leaves. Our RNA-Seq data provided a global view of transcriptomic profile of principal processes implicated in the adaptation of N deficiency in O. sativa and shed light on the candidate direction in rice breeding for green and sustainable agriculture.


Assuntos
Flavonoides/metabolismo , Lignina/metabolismo , Nitratos/metabolismo , Oryza/genética , Fotossíntese , Carboidratos/análise , Clorofila A/química , Regulação da Expressão Gênica de Plantas , Peróxido de Hidrogênio/metabolismo , Malondialdeído/metabolismo , Oryza/metabolismo , Oxirredução , Folhas de Planta/genética , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Brotos de Planta/metabolismo , RNA de Plantas/química , RNA de Plantas/metabolismo , Análise de Sequência de RNA
16.
Aquat Toxicol ; 225: 105552, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32615475

RESUMO

There is scarce investigation addressing interpopulation tolerance responses to address the influence of a history of chronic stress exposure, as that occurring in polluted environments, in photoautotrophs. We evaluated ecophysiological (photosynthetic activity) and metabolic (oxidative stress and damage) responses of two populations of green macroalga Ulva compressa from polluted (Ventanas) and non-polluted (Cachagua) localions of central Chile, and exposed to controlled hypersalinity conditions of 32 (control), 42, 62 and 82 psu (practical salinity units) for 6 h, 48 h and 6 d. Both primary production (ETRmax) and photosynthetic efficiency (αETR) were generally higher in the population from Cachagua compared to Ventanas at all times and salinities. Moreover, at most experimental times and salinities the population from Ventanas had greater levels of H2O2 and lipid peroxidation that individuals from Cachagua. Total ascorbate was higher in the population of Cachagua than Ventanas at 42 and 82 psu after 6 and 48 h, respectively, while at 6 d concentrations were similar between both populations at all salinities. Total glutathione was greater in both populations after 6 h at all salinities, but at 48 h its concentrations were higher only in the population from Cachagua, a trend that was maintained at 6 d under 82 psu only. Reduced and oxidized ascorbate (ASC and DHA, respectively) and glutathione (GSH and GSSG, respectively) demonstrated similar patterns between U. compressa populations, with an increase oxidation with greater salinities but efficient recycling to maintain sufficient batch of ASC and GSH. When assessing the expression of antioxidant enzymes catalase (CAT), superoxide dismutase (SOD) and dehydroascorbate reductase (DHAR), while the population of Ventanas displayed a general trend of upregulation with increasing salinities along the experiments, U. compressa from Cachagua revealed patterns of downregulation. Results demonstrated that although both populations were still viable after the applied hypersalinities during all experimental times, biological performance was usually more affected in the population from the Ventanas than Cachagua, likely due to a depressed baseline metabolism after a long history of exposition to environmental pollution.


Assuntos
Ulva/fisiologia , Poluentes Químicos da Água/toxicidade , Antioxidantes/metabolismo , Ácido Ascórbico/metabolismo , Catalase/metabolismo , Chile , Poluição Ambiental , Glutationa/metabolismo , Peróxido de Hidrogênio/metabolismo , Peroxidação de Lipídeos , Oxirredução , Estresse Oxidativo , Salinidade , Alga Marinha/metabolismo , Superóxido Dismutase/metabolismo , Ulva/enzimologia
17.
Cells ; 9(6)2020 06 13.
Artigo em Inglês | MEDLINE | ID: covidwho-603067

RESUMO

There is no vaccine or specific antiviral treatment for COVID-19, which is causing a global pandemic. One current focus is drug repurposing research, but those drugs have limited therapeutic efficacies and known adverse effects. The pathology of COVID-19 is essentially unknown. Without this understanding, it is challenging to discover a successful treatment to be approved for clinical use. This paper addresses several key biological processes of reactive oxygen, halogen and nitrogen species (ROS, RHS and RNS) that play crucial physiological roles in organisms from plants to humans. These include why superoxide dismutases, the enzymes to catalyze the formation of H2O2, are required for protecting ROS-induced injury in cell metabolism, why the amount of ROS/RNS produced by ionizing radiation at clinically relevant doses is ~1000 fold lower than the endogenous ROS/RNS level routinely produced in the cell and why a low level of endogenous RHS plays a crucial role in phagocytosis for immune defense. Herein we propose a plausible amplification mechanism in immune defense: ozone-depleting-like halogen cyclic reactions enhancing RHS effects are responsible for all the mentioned physiological functions, which are activated by H2O2 and deactivated by NO signaling molecule. Our results show that the reaction cycles can be repeated thousands of times and amplify the RHS pathogen-killing (defense) effects by 100,000 fold in phagocytosis, resembling the cyclic ozone-depleting reactions in the stratosphere. It is unraveled that H2O2 is a required protective signaling molecule (angel) in the defense system for human health and its dysfunction can cause many diseases or conditions such as autoimmune disorders, aging and cancer. We also identify a class of potent drugs for effective treatment of invading pathogens such as HIV and SARS-CoV-2 (COVID-19), cancer and other diseases, and provide a molecular mechanism of action of the drugs or candidates.


Assuntos
Antivirais/química , Infecções por Coronavirus/tratamento farmacológico , Infecções por Coronavirus/imunologia , Compostos Heterocíclicos/uso terapêutico , Hidrocarbonetos Halogenados/uso terapêutico , Pneumonia Viral/tratamento farmacológico , Pneumonia Viral/imunologia , Animais , Antivirais/uso terapêutico , Infecções por Coronavirus/metabolismo , Humanos , Peróxido de Hidrogênio/metabolismo , Lisossomos/efeitos dos fármacos , Pandemias , Fagocitose , Pneumonia Viral/metabolismo , Explosão Respiratória/efeitos dos fármacos , Transdução de Sinais
18.
Proc Natl Acad Sci U S A ; 117(27): 15827-15836, 2020 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-32571911

RESUMO

Bromine and peroxidasin (an extracellular peroxidase) are essential for generating sulfilimine cross-links between a methionine and a hydroxylysine within collagen IV, a basement membrane protein. The sulfilimine cross-links increase the structural integrity of basement membranes. The formation of sulfilimine cross-links depends on the ability of peroxidasin to use bromide and hydrogen peroxide substrates to produce hypobromous acid (HOBr). Once a sulfilimine cross-link is created, bromide is released into the extracellular space and becomes available for reutilization. Whether the HOBr generated by peroxidasin is used very selectively for creating sulfilimine cross-links or whether it also causes oxidative damage to bystander molecules (e.g., generating bromotyrosine residues in basement membrane proteins) is unclear. To examine this issue, we used nanoscale secondary ion mass spectrometry (NanoSIMS) imaging to define the distribution of bromine in mammalian tissues. We observed striking enrichment of bromine (79Br, 81Br) in basement membranes of normal human and mouse kidneys. In peroxidasin knockout mice, bromine enrichment of basement membranes of kidneys was reduced by ∼85%. Proteomic studies revealed bromination of tyrosine-1485 in the NC1 domain of α2 collagen IV from kidneys of wild-type mice; the same tyrosine was brominated in collagen IV from human kidney. Bromination of tyrosine-1485 was reduced by >90% in kidneys of peroxidasin knockout mice. Thus, in addition to promoting sulfilimine cross-links in collagen IV, peroxidasin can also brominate a bystander tyrosine. Also, the fact that bromine enrichment is largely confined to basement membranes implies that peroxidasin activity is largely restricted to basement membranes in mammalian tissues.


Assuntos
Membrana Basal/metabolismo , Bromo/metabolismo , Proteínas da Matriz Extracelular/metabolismo , Peroxidase/metabolismo , Animais , Biópsia , Bromatos/metabolismo , Brometos , Células Cultivadas , Colágeno Tipo IV/metabolismo , Humanos , Peróxido de Hidrogênio/metabolismo , Iminas/metabolismo , Rim/citologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteômica
19.
PLoS Pathog ; 16(6): e1008559, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32497109

RESUMO

Antibiotics continue to be the standard-of-care for bacterial vaginosis (BV), although recurrence rates are high. Vaginal probiotics may improve durability of BV treatment, although few probiotics for vaginal health contain Lactobacillus spp. that commonly colonize the lower female genital tract. Characteristics of vaginal Lactobacillus strains from South African women were evaluated for their probiotic potential in vitro compared to strains from commercial vaginal products, including growth at varying pHs, ability to lower pH, produce D-/L-lactate and H2O2, influence growth of BV-associated Gardnerella vaginalis and Prevotella bivia, adherence to cervical cells and susceptibility to antibiotics. Fifty-seven Lactobacillus strains were purified from cervico-vaginal fluid, including L. crispatus, L. jensenii, L. gasseri, L. mucosae, and L. vaginalis. L crispatus strains grew better at pHs below 4.5 and lowered pH more effectively than other strains. Production of D-/L-lactate and H2O2 varied between Lactobacillus species and strains. Lactobacillus strains generally inhibited P. bivia more uniformly than G. vaginalis isolates. All vaginal Lactobacillus isolates were resistant to metronidazole while susceptibility to clindamycin varied. Furthermore, vaginal Lactobacillus strains tended to be broadly susceptible to penicillin, amoxicillin, rifampicin and rifabutin. Whole-genome-sequencing of five of the best-performing vaginal Lactobacillus strains confirmed their likely safety, due to antimicrobial resistance elements being largely absent, while putative intact prophages were present in the genomes of two of the five strains. Overall, vaginal Lactobacillus strains largely performed better in these in vitro assays than probiotic strains currently used in probiotics for vaginal health. Including the best-performing vaginal Lactobacillus isolates in a region-specific probiotic for vaginal health may result in improved BV treatment options.


Assuntos
Infecções por Bacteroidaceae/microbiologia , Gardnerella vaginalis , Infecções por Bactérias Gram-Positivas/microbiologia , Lactobacillus , Prevotella , Vaginose Bacteriana/microbiologia , Adolescente , Adulto , Infecções por Bacteroidaceae/tratamento farmacológico , Infecções por Bacteroidaceae/genética , Infecções por Bacteroidaceae/metabolismo , Clindamicina/farmacologia , Farmacorresistência Bacteriana/efeitos dos fármacos , Farmacorresistência Bacteriana/genética , Feminino , Infecções por Bactérias Gram-Positivas/tratamento farmacológico , Infecções por Bactérias Gram-Positivas/genética , Infecções por Bactérias Gram-Positivas/metabolismo , Humanos , Peróxido de Hidrogênio/metabolismo , Ácido Láctico/metabolismo , Lactobacillus/genética , Lactobacillus/isolamento & purificação , Lactobacillus/metabolismo , Metronidazol/farmacologia , África do Sul , Especificidade da Espécie , Vaginose Bacteriana/tratamento farmacológico , Vaginose Bacteriana/genética
20.
Cells ; 9(6)2020 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-32545714

RESUMO

There is no vaccine or specific antiviral treatment for COVID-19, which is causing a global pandemic. One current focus is drug repurposing research, but those drugs have limited therapeutic efficacies and known adverse effects. The pathology of COVID-19 is essentially unknown. Without this understanding, it is challenging to discover a successful treatment to be approved for clinical use. This paper addresses several key biological processes of reactive oxygen, halogen and nitrogen species (ROS, RHS and RNS) that play crucial physiological roles in organisms from plants to humans. These include why superoxide dismutases, the enzymes to catalyze the formation of H2O2, are required for protecting ROS-induced injury in cell metabolism, why the amount of ROS/RNS produced by ionizing radiation at clinically relevant doses is ~1000 fold lower than the endogenous ROS/RNS level routinely produced in the cell and why a low level of endogenous RHS plays a crucial role in phagocytosis for immune defense. Herein we propose a plausible amplification mechanism in immune defense: ozone-depleting-like halogen cyclic reactions enhancing RHS effects are responsible for all the mentioned physiological functions, which are activated by H2O2 and deactivated by NO signaling molecule. Our results show that the reaction cycles can be repeated thousands of times and amplify the RHS pathogen-killing (defense) effects by 100,000 fold in phagocytosis, resembling the cyclic ozone-depleting reactions in the stratosphere. It is unraveled that H2O2 is a required protective signaling molecule (angel) in the defense system for human health and its dysfunction can cause many diseases or conditions such as autoimmune disorders, aging and cancer. We also identify a class of potent drugs for effective treatment of invading pathogens such as HIV and SARS-CoV-2 (COVID-19), cancer and other diseases, and provide a molecular mechanism of action of the drugs or candidates.


Assuntos
Antivirais/química , Infecções por Coronavirus/tratamento farmacológico , Infecções por Coronavirus/imunologia , Compostos Heterocíclicos/uso terapêutico , Hidrocarbonetos Halogenados/uso terapêutico , Pneumonia Viral/tratamento farmacológico , Pneumonia Viral/imunologia , Animais , Antivirais/uso terapêutico , Infecções por Coronavirus/metabolismo , Humanos , Peróxido de Hidrogênio/metabolismo , Lisossomos/efeitos dos fármacos , Pandemias , Fagocitose , Pneumonia Viral/metabolismo , Explosão Respiratória/efeitos dos fármacos , Transdução de Sinais
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