Oxidative damage induced by herbicides is mediated by thiol oxidation and hydroperoxides production

Effects of Different Ammonia Levels on Tribenuron Methyl Toxicity in Daphnia magna

The present study investigates the toxicity of the herbicide tribenuron methyl (TBM) as an anthropogenic agent and ammonia as an abiotic factor on Daphnia magna at environmentally relevant concentrations. These stressors may coexist in surface waters in agricultural regions. To achieve this objective, D. magna were exposed to TBM at a nominal concentration of 0.81 μg/L in association with a low ammonia (LA) concentration of 0.65 mg/L and a high ammonia (HA) concentration of 1.61 mg/L in acute toxicity tests of 96-h duration and chronic toxicity tests of 21-day duration. The D. magna also were exposed to TBM, HA, and LA singly. The D. magna were analysed for various biomarkers of sublethal toxicity. Glutathione peroxidase (GPx), glutathione S-transferase (GST), cholinesterase (ChE) enzyme activities, and levels of thiobarbituric acid reactive substances (TBARS) and total protein were determined spectrophotometrically. Mitochondrial membrane potential (MMP) was analysed by microscopy with fluorescence staining. Cytochrome c and 5' AMP-activated protein kinase (AMPK) were analysed by Western blotting. Morphometric properties were examined microscopically. This is the first study in which AMPK, an indicator of intracellular energy, was measured in D. magna. GST and ChE enzyme activities and TBARS and total protein levels did not change during acute exposures (i.e., 96 h) in all treatments. GPx activity increased in D. magna from the HA + TBM treatment compared with single-exposure groups. The level of cytochrome c protein was elevated in D. magna from the LA and LA + TBM treatments. AMPK protein levels increased in all treatments with daphnids, except in the LA group. MMP was depolarised in D. magna from all treatments, whereas the most notable change was observed in HA + TBM mixture group in chronic exposures. The results show that GST and ChE may not be sensitive biomarkers for evaluating the sublethal toxic effects to D. magna exposed to environmentally relevant concentrations of ammonia and TBM. Acute and chronic exposure to ammonia and TBM probably caused an energetic crisis in D. magna. Therefore, AMPK and MMP are promising biomarkers for these toxicants.

Biochemical changes and antioxidant capacity of naringin and naringenin against malathion toxicity in Saccharomyces cerevisiae

Flavonoids are rich in seeds, citrus fruits, olive oil, tea and red wine. Citrus flavonoids constitute an important type of flavonoids. Naringin and naringenin belong to flavonoids with known antioxidant and were found to display antioxidant activities. Malathion is an organophosphorus pesticide that has been broadly used throughout the world to control weeds and pests. It has also been used in public health for mosquito control and fruit fly eradication programs. Malathion, naringin, and naringenin were added to be in 40, 80, and 160 mg doses in Saccharomyces cerevisiae cultures mainly used to determine the antioxidant capacity, it is known that they have shown similar results to man. At the end of the experiment, total protein, malondialdehyde (MDA), reduced glutathione (GSH), oxidized glutathione (GSSG), vitamin K, vitamin E, vitamin D, ergosterol, stigmasterol, β-Sitosterol, and fatty acids were analyzed by HPLC (high performance liquid chromatography) and GC (gas chromatography) devices in the tested S. cerevisiae samples. The contents of the yeast cell of octanoic acid (C8:0), lauric acid (C12:0), myristic acid (C14:0), palmitic acid (C16:0), palmitoleic acid (C16:1n-7), heptadecanoic acid (C17:0), stearic acid (C18:0), oleic acid (C18:1n-9), and linoleic acid (C18:2n-6) were identified. There were statistically significant changes in total protein, MDA, GSH, GSSG, vitamin K, vitamin E, vitamin D, phytosterol and fatty acid levels. It was determined that naringin and naringenin showed statistically significant decreases against malathion toxicity on these parameters. From this study it is found that, the mitigating effect of naringin against DPPH stable free radical was higher than that of naringenin. Citrus flavonoid, naringin showed promising antioxidant activity which can be used as effective protecting agents against oxidative stress.

Combining proteomics and lipid analysis to unravel Confidor stress response in Saccharomyces cerevisiae

The yeast Saccharomyces cerevisiae is a useful model for studying the influence of different stress factors on eukaryotic cells. In this work we used the pesticide imidacloprid, in the Confidor formulation, as the stress factor and analyzed its influence on the metabolic activity, proteome and lipid content and composition of Saccharomyces cerevisiae yeast. During the cultivation of yeast, the lowest recommended application dose of Confidor (0.025%, v/v) was added to the growth media and its influence on the mitochondria, cytosol with microsomes, and the whole yeast cells was monitored. The results show that under the stress provoked by the toxic effects of Confidor, yeast cells density significantly decreased and the percentage of metabolically disturbed cells significantly increased comparing with untreated control. Also, there was a downregulation of majority of glycolytic, gluconeogenesis, and TCA cycle enzymes (Fba1, Adh1, Hxk2, Tal1, Tdh1,Tdh3, Eno1) thus providing enough acetyl-CoA for the lipid restructuring and accumulation mechanism since we have found the changes in the cell and mitochondrial lipid content and FA composition. This data suggest that lipids could be the molecules that orchestrate the answer of the cells in the stress response to the Confidor treatment.

Effects of selenium on oxidative damage and antioxidant enzymes of eukaryotic cells: wine Saccharomyces cerevisiae

AIM

To clarify the effects of selenium (Se), parameters related to oxidative issues, as well as the antioxidant response were investigated on an autochthonous wine yeast strain.

METHODS AND RESULTS

Antioxidant enzyme activity, gel electrophoresis, Western blot and MDA level were used to investigate the effects of different concentration of Se in wine yeast. We found that Se is able to affect the enzymatic activities of catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD). An increase in lipid peroxidation was observed in a dose-dependent manner of (Se), thus, indicating the occurrence of cell membrane damage. Additionally, Se induced post-translational oxidative modifications of proteins, especially oxidation of thiol groups (both reversible and irreversible) and protein carbonylation (irreversible oxidation).

CONCLUSION

These results obtained could further the understanding the effect of different concentration of Se in wine yeast strain with which Se affect the enzymatic activities and induces some post-translational modifications of proteins.

SIGNIFICANCE AND IMPACT OF THE STUDY

The understanding of mechanisms regulating the response of wine yeast to Se is important for future work using selenized yeast as enriched Se supplements in human nutrition.

Protein identification before and after glyphosate exposure in Lolium multiflorum genotypes

BACKGROUND

Weeds reduce crop yields, and among the methods used to control these plants, the use of chemicals is preferred. However, the repeated application of herbicides with the same mechanism of action selects for resistant populations. The aim of this study was to evaluate glyphosate resistance in Lolium multiflorum (Lam.) and relate the resistance to protein expression in the absence and presence of the herbicide using a metabolic-proteomic approach.

RESULTS

Glyphosate resistance was confirmed, with a sevenfold difference in resistance between susceptible and resistant genotypes. Among the possible mechanisms affecting resistance, mutations in the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), herbicide differential translocation and overexpression of EPSPS are suggested. Susceptible plants had higher growth than did resistant plants in the absence of the herbicide, in addition to greater expression of protein groups related to photosynthesis and to tolerance to biotic and abiotic stresses. With application of glyphosate, resistant plants maintained their metabolism and began to express EPSPS and other candidate proteins related to herbicide resistance.

CONCLUSIONS

In the absence of glyphosate, the susceptible plants would replace the resistant plants over time, and abiotic or biotic stresses would accelerate this process. Resistance in plants resulted from a combination of target-site and non-target-site resistance mechanisms. We identified several candidate proteins that could be investigated in future studies on glyphosate resistance. © 2017 Society of Chemical Industry.

Upregulation of Oxidative Stress Related Genes in a Chronic Kidney Disease Attributed to Specific Geographical Locations of Sri Lanka

Objective. To infer the influence of internal and external oxidative stress in chronic kidney disease patients of unknown etiology (CKDu) in Sri Lanka, by analyzing expression of genes related directly or indirectly to oxidative stress: glutamate-cysteine ligase catalytic subunit (GCLC), glutathione S-transferase mu 1 (GSTM1), glucose-6-phosphate dehydrogenase (G6PD), fibroblast growth factor-23 (FGF23), and NLR family pyrin domain containing 3 (NLRP3). Methods. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was carried out for the selected populations: CKDu patients (n = 43), chronic kidney disease patients (CKD; n = 14), healthy individuals from a CKDu endemic area (GHI; n = 9), and nonendemic area (KHI; n = 16). Fold changes were quantified relative to KHI. Results. GCLC had greater than threefold upregulation in all three study groups, with a maximum of 7.27-fold upregulation in GHI (p = 0.000). GSTM1 was not expressed in 25.6% of CKDu and 42.9% of CKD patients, but CKDu patients expressing GSTM1 showed upregulation of 2.60-fold (p < 0.05). Upregulation of FGF23 and NLRP3 genes in CKD and CKDu was observed (p < 0.01), with greater fold changes in CKD. Conclusion. Results suggest higher influence of external sources of oxidative stress in CKDu, possibly owing to environmental conditions.

Saccharomyces cerevisiae as a model in ecotoxicological studies: A post-genomics perspective

The budding yeast Saccharomyces cerevisiae represents a well-consolidated and widely used eukaryotic model, with a number of features that make it an ideal organism to carry out functional toxicological studies. Several advantages are permitted by the use of yeast cells, as the possibility to identify molecular biomarkers, unknown mechanisms of action and novel potential targets. Thanks to the evolutionary conservation, yeast can provide also useful clues allowing the prioritization of more complex analyses and toxicity predictions in higher eukaryotes. The last two decades were incredibly fruitful for yeast "omics", but referring to the analysis of the effects of pesticides on yeast much still remains to be done. Furthermore, a deeper knowledge of the effects of environmental pollutants on biotechnological processes associated with the use of yeasts is to be hoped.

Pesticides and human chronic diseases: evidences, mechanisms, and perspectives

Along with the wide use of pesticides in the world, the concerns over their health impacts are rapidly growing. There is a huge body of evidence on the relation between exposure to pesticides and elevated rate of chronic diseases such as different types of cancers, diabetes, neurodegenerative disorders like Parkinson, Alzheimer, and amyotrophic lateral sclerosis (ALS), birth defects, and reproductive disorders. There is also circumstantial evidence on the association of exposure to pesticides with some other chronic diseases like respiratory problems, particularly asthma and chronic obstructive pulmonary disease (COPD), cardiovascular disease such as atherosclerosis and coronary artery disease, chronic nephropathies, autoimmune diseases like systemic lupus erythematous and rheumatoid arthritis, chronic fatigue syndrome, and aging. The common feature of chronic disorders is a disturbance in cellular homeostasis, which can be induced via pesticides' primary action like perturbation of ion channels, enzymes, receptors, etc., or can as well be mediated via pathways other than the main mechanism. In this review, we present the highlighted evidence on the association of pesticide's exposure with the incidence of chronic diseases and introduce genetic damages, epigenetic modifications, endocrine disruption, mitochondrial dysfunction, oxidative stress, endoplasmic reticulum stress and unfolded protein response (UPR), impairment of ubiquitin proteasome system, and defective autophagy as the effective mechanisms of action.

Linking protein oxidation to environmental pollutants: redox proteomic approaches

Environmental pollutants, such as compounds used in agriculture or deriving from vehicles, industries and human activities, can represent major concern for human health since they are considered to contribute significantly to many diseased states with major public health significance. Besides considerable epidemiological evidence linking environmental pollutants with adverse health effects, little information is provided on the effects of these compounds at the cellular and molecular level. Though oxidative stress is generally acknowledged as one of the most important mechanisms of action for pollutant-induced toxicity, redox proteomics, the elective tool to identify post-translationally oxidized proteins, is still in its very infancy in this field of investigation. This review will provide the readers with an outline of the use of redox proteomics in evaluating pollutant-induced oxidative damage to proteins in various biological systems. Future potential applications of redox proteomic approaches from an environmental point of view will be discussed as well.