Specific Activity Of Glutathione S-transferase Research Articles

Polycyclic aromatic hydrocarbon (PAH) activation of AhR inhibits glutathione S-transferase (GST) activity in primary human small airway epithelial cells (hSAECs)

Background: PAH represents the organic phase of particulate matter (PM) in air pollution emitted via the incomplete combustion of various compounds (i.e. diesel fuel, wood, and plastics). It is widely regarded that PAH activation of aryl hydrocarbon receptor (AhR) plays an important role in pro-inflammatory signaling, however the mechanisms remain unknown. In contrast- endogenous AhR agonists, such as 6-Formylindolo[3,2-b]carbazole (FICZ), exert pleiotropic protective effects against inflammation, fibrosis, and oxidative stress. The objective of our research program is to delineate the differences between activation of AhR by PAH (with adverse effects) compared to its beneficial homeostatic activation by endogenous FICZ. PM may induce oxidative stress in part through inhibition of antioxidant defense mechanisms. GSTs are a superfamily of enzymes that plays an important role in protecting cells from oxidative damage (by conjugating reduced glutathione to substrates under pro-oxidizing conditions). We hypothesize that PAH activation of AhR contributes to oxidative stress via inhibition of GST activity in primary hSAECs. Methods: Primary hSAECs were subjected to varying dosages of PAH [0, 250, 500, 1000, 5000 ng/mL] to model airborne PM exposure levels, and to increasing doses of FICZ [0, 0.50, 10, 100, 1000 nM] to model normal and excessively high endogenous ligand activation of AhR. We determined the relative potencies of PAH and FICZ by measuring CYP1A1 and CYP1B1 gene expression. Oxidative stress was measured using DHE-labeling and GST activity was measured with enzymatic kits (Sigma Aldrich). AhR activity was pharmacologically inhibited using 10μM CH223191. Statistical analysis was conducted using SigmaPlot 14.0 (Systat Software). Results: PAH and FICZ maximally stimulate hSAEC CYP1A1 and CYP1B1 expression at 1000ng/mL and 100nM, respectively, and are therefore defined as equipotent concentrations used in our studies. In a representative experiment in hSAECs, PAH (1000ng/mL) significantly increased hSAEC oxidative stress vs FICZ (100nM) n=6, p<0.01), while significantly decreasing GST specific activity vs equipotent FICZ activation of AhR in primary hSAECs from a 66-year-old female without lung disease (26.6±0.874 vs 28.3±.611 nmol/mL/min); n=6 from 2 independent assays; p=0.032. Similar differential effects of PAH vs FICZ activation of AhR on GST were seen in additional experiments with male hSAECs and Calu-3 cells (male). Importantly, CH223191 inhibition of GST enzymatic activity suggests that AhR plays an important role in protecting cells from oxidative stress. Conclusions: Our studies indicate that airborne PAH exposure can have detrimental health effects on the lung via aberrant AhR signaling. Significance: Understanding activity of AhR signaling can leads to novel therapeutic options for redox disorders in the lung. Funding: VA 5I01BX001777-05 (RP) and R01HL137033 (MH). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effects of alcohol-graded concentrations on total thiols and some thiol utilizing enzymes

Excessive intake of alcohol has been documented to initiate different pathological conditions. Although various researchers have reported these associations, the modulatory effects on endogenous thiols are not well studied. This study investigated the effects of alcohol-graded concentrations on some thiol utilizing enzymes in rats. Adults’ male rats were divided into four main groups and treated with distilled water, 30 %, 40 % and 50 % alcohol (3.20 g / Kg body weight). Five rats from each group were sacrificed at the end of 1, 7, 14, 21, and 28 day(s) of the experiment. Assay of glutathione peroxidase and glutathione S-transferase specific activities along with total thiols levels were carried out. Alcohol administration resulted in an upregulation of the activities of glutathione peroxidase and glutathione S-transferase with concomitant depletion of total thiols concentrations. Conclusively, this study affirms that graded dosages of alcohol administration to rats induced perturbations in the thiol utilizing system in a non-time dependent consistent manner.

Berberis lyceum root bark extract attenuates anticancer drugs induced neurotoxicityand cardiotoxicity in rats.

Traditionally, Berberis lyceum was extensively used for the treatment of several human diseases. This study was undertaken to determine in vivo effects of Berberis lyceum root bark against doxorubicin-induced cardiotoxicity and cisplatin-induced neurotoxicity in Sprague Dawley rats. A single dose of doxorubicin (20 mg/ kg i. p) and cisplatin (4mg/kg i.p) was used to induce cardiotoxicity and neurotoxicity, respectively. Berberis lyceum methanolic extract was given orally (200 and 400 mg/ kg) to toxicity-induced rats. The cardiac biomarkers i.e. serum aspartate aminotransferase, alanine transaminase, lactate dehydrogenase, creatine kinase and creatine kinase MB were analyzed in blood collected from cardiotoxic rats. The tissue oxidative stress markers included protein, glutathione s-transferase specific activity, catalase activity, total glutathione, and malondialdehyde levels were measured in cardiac and brain homogenate of the respective groups. Berberis lyceum methanolic extract has the potential to reduce the doxorubicin-induced cardiotoxicity and cisplatin-induced neurotoxicity significantly (*p<0.05) by reducing the serum markers and oxidative stress parameters. Histopathological analysis exhibited a marked improvement in the morphology of cardiac and brain tissues. It is concluded that methanolic extract of Berberis lyceum root bark has the potential to protect and reverse anticancer drugs induced cardiotoxicity and neurotoxicity.

The effects of mepiquat chloride (DPC) on the soluble protein content and the activities of protective enzymes in cotton in response to aphid feeding and on the activities of detoxifying enzymes in aphids

BackgroundMepiquat chloride (DPC) enhances the resistance of cotton plants, and it is widely used as a growth regulator. DPC can stimulate photosynthesis, stabilize the structure of cotton leaves, and affect population reproduction and energy substances in Aphis gossypii Glover (cotton aphids), but interactions between DPC and cotton aphids remain unclear. In this study, we analyzed the physiological responses of cotton to DPC, and the toxicity of DPC toward cotton aphids, before and after feeding, to explore the DPC-induced defense mechanism against cotton aphids.ResultsMeasurements of protective enzyme activity in cotton showed that the soluble protein contents, peroxidase (POD) activity, and catalase (CAT) activity in cotton treated with different concentrations of DPC were higher than in the control. Superoxide dismutase (SOD) activity was higher than that of the control when the concentration of DPC was < 0.1 g/L. Under aphid feeding stress, POD activity in cotton treated with a low insect population density was significantly lower than in the controls, but the reverse was true for cotton treated with a high insect population density, and SOD activity was positively correlated with population density. The activities of detoxification enzymes in field and laboratory experiments showed that DPC promoted the specific activity of glutathione S-transferase (GST) in cotton aphids, while the specific activities of carboxylesterase (CarE) and acetylcholinesterase (AchE) were decreased.ConclusionsDPC enhanced the aphid resistance in cotton by increasing the soluble protein content and the activity of protective enzymes. It also had a toxic effect on cotton aphids by increasing GST activity (the main DPC target). DPC increased the soluble protein content and protective enzymes activity in cotton under aphid stress, and thereby enhanced tolerance to cotton aphids. It conclude that DPC interferes with cotton aphids through indirect (DPC induced cotton defense responses) and direct (DPC toxicity to cotton aphids) ways, which plays a positive role in interfering with cotton aphids.

New alternative for culicidian fauna control using Borago officinalis and Drimia maritima plant extracts

Abstract. Djeddar H, Boudjelida H, Arroussi DER. 2021. New alternative for culicidian fauna control using Borago officinalis and Drimia maritima plant extracts. Biodiversitas 22: 5688-5694. Focus on the development of insecticides based on botanical extracts may represent an alternative environmentally interesting tool to chemical control. The current study aimed to investigate the effects of both extracts of Drimia maritima (Asparagales: Asparagaceae) and Borago officinalis (Lamiales: Boraginaceae) on larvae sensibility, physiological and biochemical parameters of Culex pipiens (Diptera: Culicidae). The larvicidal bioassay exhibits a significant dose-response relationship against the fourth instar larvae of Cx. pipiens. Moreover, biochemical analyses revealed a decrease in proteins levels, carbohydrates and lipids in the whole larvae body treated with the lethal concentrations (LC50, LC90) of D. maritima extract as compared to the control series. Whereas, using B. officinalis herbal plants, the result showed a decrease in lipid and carbohydrate contents and an increase in protein. The ability of D. maritima and B. officinalis extracts to inhibit acetylcholinesterase (AChE) activity in a whole body of the treated larvae of Cx. pipiens is examined. The estimated specific activity of glutathione S-transferase (GST) at different times was significantly increased under the effects of both plants. The present study demonstrates that the aqueous extracts of D. maritima and B.officinalis present insecticidal properties with neurotoxic effects against larval stages of the domestic mosquito Cx. pipiens. In this context, the use of chemical insecticides for mosquito control is no longer recommended and the alternatives of eco-friendly products are encouraged.

Stable knockout of lanthionine synthase C-like protein-1 (LanCL1) from HeLa cells indicates a role for LanCL1 in redox regulation of deubiquitinating enzymes

Lanthionine synthase C-like protein-1 (LanCL1) is a glutathione (GSH)-binding protein of uncertain function, widely expressed in mammalian cells. Recent data suggests that LanCL1 has glutathione S-transferase (GST)-like activity, while other reports claim that LanCL1 suppresses mitogen-activated kinase (MAPK) phosphorylation. In the present study, recombinant human LanCL1 had less than 10% the specific activity of GST. When CRISPR-Cas9 was used to stably ablate LanCL1 from HeLa cells, the resulting line was sensitized to H2O2 toxicity. [GSH], [GSSG], [GSH]/[GSSG] and GST activity were unaltered by LanCL1 knockout but glutathione reductase and glutathione peroxidase activities were significantly elevated. LanCL1-KO cells did not differ in basal or H2O2–induced p38-MAPK, ERK p42/p44 or JNK phosphorylation; however, MAPK-targeted transcription factor regulators c-Jun and IκBα were significantly decreased. Because c-Jun and IκBα levels are ubiquitin regulated, experiments addressed the hypothesis that LanCL1 affects ubiquitination dynamics. In the presence of the 26S proteasome inhibitor bortezomib, ubiquitinated proteins accumulated faster in LanCL1-KO cells, suggesting that LanCL1 positively regulates deubiquitination. The activity of ubiquitin C-terminal hydrolase (UCH), a major deubiquitinase (DUB) subclass, was significantly decreased in LanCL1-KO cells while protein levels of A20/TNFAIP3, USP9X and USP10 DUBs were significantly reduced. UCH activity in HeLa cell lysates was lost upon treatment with H2O2 and significantly recovered by addition of recombinant LanCL1 plus GSH. Taken together these data suggest that LanCL1 likely does not act as a GST-like enzyme in vivo, but rather modulates ubiquitin-dependent cell signaling pathways through positive regulation of redox-sensitive DUBs.

Multi-biomarkers approach to the assessment of the southeastern Mediterranean Sea health status: Preliminary study on Stramonita haemastoma used as a bioindicator for metal contamination

The present study aimed to evaluate the responses of different biochemicals parameters associated with environmental pollution in the digestive gland of the gastropod mollusc Stramonita haemastoma. Physiochemical parameters and trace metal elements (Copper (Cu), Zinc (Zn), Chromium (Cr), Cadmium (Cd) and Lead (Pb)) were measured in seawater. Spatiotemporal variations in reduced glutathione (GSH), malondialdehyde (MDA) and metallothionein (Mt) as well as the specific activities of glutathione S-transferase (GST) and catalase (CAT) were evaluated in digestive gland of this species during a one-year period in 2013–2014. Samples collection was conducted at three sites. The results obtained showed seasonal fluctuations in GST and CAT activities and in the rate of Mt content. In addition, intersite variations in GSH, MDA, Mt and CAT were recorded in individuals. Also, trace metal elements concentrations determined by season in the digestive gland revealed spatial and temporal variations for Cu and Zn but they are below the limit of detection for Cd and Pb. The highest values were generally recorded in spring for Cu and in winter for Zn. In this first regional study using in S. haemastoma as a model, the biomarkers measured were seen to be inducible parameters to evaluate the health state of the organism and the overall quality of the study sites.

Monosodium glutamate-induced obesity changed the expression and activity of glutathione S-transferases in mouse heart and kidney.

Obesity may affect activity and/or expression of enzymes participating in xenobiotics' detoxification and antioxidant defense. This study sought to investigate the activities and expression of cardiac and renal glutathione S-transferase (GST) isoforms in order to reveal possible differences between obese and control mice. For this purpose, mice with monosodium glutamate (MSG)-induced obesity were used as an experimental model. Obesity was induced in newborn male mice by repeated s.c. administration of MSG. At 8 months of age, mice were sacrificed and specific activity, protein and mRNA expressions levels of GSTs were analyzed in their heart and kidney. In hearts of obese mice, specific activity of GST was decreased by 51% compared to control. This reduction was accompanied by a decline in GSTP-class protein and Gstp1/2 mRNA expression levels. In contrast, specific activity of GST was elevated by 31% in kidney of obese mice and this increase was accompanied by upregulation of GSTA-class protein and Gsta1/2 mRNA expressions. Increased capacity of renal GSTs together with GSTA upregulation may serve as compensatory mechanism against elevated oxidative stress, which accompanies obesity. On the other hand, decreased cardiac GST activity in obese mice and GSTP downregulation may worsen the defense against oxidative stress and harmful xenobiotics.

Oyster's cells regulatory volume decrease: A new tool for evaluating the toxicity of low concentration hydrocarbons in marine waters

Human activities require fossil fuels for transport and energy, a substantial part of which can accidentally or voluntarily (oil spillage) flow to the marine environment and cause adverse effects in human and ecosystems' health. This experiment was designed to estimate the suitability of an original cellular biomarker to early quantify the biological risk associated to hydrocarbons pollutants in seawater. Oocytes and hepatopancreas cells, isolated from oyster (Crassostrea gigas), were tested for their capacity to regulate their volume following a hypo-osmotic challenge. Cell volumes were estimated from cell images recorded at regular time intervals during a 90min-period. When exposed to diluted seawater (osmolalities from 895 to 712mosmkg−1), both cell types first swell and then undergo a shrinkage known as Regulatory Volume Decrease (RVD). This process is inversely proportional to the magnitude of the osmotic shock and is best fitted using a first-order exponential decay model. The Recovered Volume Factor (RVF) calculated from this model appears to be an accurate tool to compare cells responses. As shown by an about 50% decrease in RVF, the RVD process was significantly inhibited in cells sampled from oysters previously exposed to a low concentration of diesel oil (8.4mgL−1 during 24h). This toxic effect was interpreted as a decreased permeability of the cell membranes resulting from an alteration of their lipidic structure by diesel oil compounds. In contrast, the previous contact of oysters with diesel did not induce any rise in the gills glutathione S-transferase specific activity. Therefore, this work demonstrates that the study of the RVD process of cells selected from sentinel animal species could be an alternative bioassay for the monitoring of hydrocarbons and probably, of various chemicals in the environment liable to alter the cellular regulations. Especially, given the high sensitivity of this biomarker compared with a proven one, it could become a relevant and accurate tool to estimate the biological hazards of micropollutants in the water.

Tannic Acid Induction of a GlutathioneS-transferase inMicromelalopha troglodyta(Lepidoptera: Notodontidae) Larvae

Abstract Micromelalopha troglodyta (Graeser) (Lepidoptera: Notodontidae) is an important pest of poplar trees, Populus spp. (family Salicaceae), in China. Herein, we report the first cloning and sequencing of a full-length cDNA of a delta class (Class I) glutathione S-transferase (GST), MtGSTd1, from the larval midgut of M. troglodyta. The open reading frame of the MtGSTd1 cDNA was 657 bp and encoded 219 amino acid residues in M. troglodyta. Furthermore, specific activities of GSTs were induced in fat bodies and midguts of M. troglodyta by tannic acid. MtGSTd1 mRNA also was induced by tannic acid in the fat bodies and midguts. GST activities increased following the elevated expression of GST mRNA in M. troglodyta. These findings indicate that the GSTs may have an antioxidant role in the metabolism of plant secondary substances in M. troglodyta larvae.

The Association between Anti - Oxidant , Redox Status and Sister Chromatid Exchanges in down Syndrome Individuals

The main objective of this project is to study the possible association between anti-oxidant/redox status and DNA instability in Down syndrome. The activities of 5 antioxidant enzymes were studied in 19 Down syndrome (DS) cases and in age- and sex-matched normal controls. Sister Chromatid Exchanges (SCE) were measured in lymphocyte cultures derived from all DS and control subjects. All DS and control individuals had normal hematological parameters, but the proliferation and mitotic indices were significantly lower in the DS- than in the controls-derived lymphocyte cultures, while the average generation time was higher than that in the controls. The specific activity of superoxide dismutase in the DS individuals was 40% higher than that in the controls, while the specific activity of glutathione S-transferase in the DS group was significantly lower than that in the controls (P ≤ 0.05). Catalase and glutathione peroxides’ activities were not different between the two groups (P > 0.05). SCE rate in the DS derived cultures was significantly higher (P < 0.001) than that of the controls. DS individuals have a higher oxidative stress, higher superoxide dismutase activities and higher rates of SCE in their derived lymphocyte cultures compared to those of the controls. We claim that such differences may have resulted from the over expression of superoxide dismutase gene, leading to imbalanced cellular antioxidant mechanisms and, consequently, resulted in a high concentration of free radicals that destabilized the DNA as expressed by the high rate of SCE.

Legionella pneumophila transcriptional response to chlorine treatment

Legionella pneumophila is a ubiquitous environmental microorganism found in freshwater that can cause an acute form of pneumonia known as Legionnaires’ disease. Despite widespread use of chlorine to ensure drinking water quality and awareness that L. pneumophila may escape these treatments, little is known about its effects on L. pneumophila. The aim of this study was to investigate the L. pneumophila transcriptional response induced by chlorine treatment. Transcriptome analysis, using DNA arrays, showed that a sublethal dose of chlorine induces a differential expression of 391 genes involved in stress response, virulence, general metabolism, information pathways and transport. Many of the stress response genes were significantly upregulated, whereas a significant number of virulence genes were repressed. In particular, exposure of L. pneumophila to chlorine induced the expression of cellular antioxidant proteins, stress proteins and transcriptional regulators. In addition, glutathione S-transferase specific activity was enhanced following chlorine treatment. Our results clearly indicate that chlorine induces expression of proteins involved in cellular defence mechanisms against oxidative stress that might be involved in adaptation or resistance to chlorine treatment.

Antioxidant activity and the effect of different parts of areca catechu extracts on Glutathione-S-Transferase activity in vitro

ABSTRACT Areca nut ( Areca catechu L.) or Pinang is one of the most widely used psychoactive substance with several hundred million users worldwide, predominantly in Southern Asia. This study evaluates the antioxidant activity and the total phenolic compound of methanolic and aqueous extract of seeds (ripe and unripe seeds), root and adventitious root. The antioxidant activity was determined using the 1, 1 -diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay and total phenolic using the Folin-Ciocalteu method. The results from this study showed that the antioxidant activities of the water and methanolic extracts of the seeds as determined by the 1, 1 -Diphenyl-2-picrylhydrazyl (DPPH) presented higher percentage inhibition than the root and adventitious root. The methanol extracts gave higher antioxidant activities than the aqueous extracts and comparable to that BHT and Vitamin C. The results also showed that unripe seeds methanolic extract possessed higher content of phenolic (186.2 ± 0.04 mg GAE/g) and total flavonoid (18.13 ± 0.007 mg/g) than other parts of A. catechu. We also evaluated the in vitro effect of various A.catechu methanolic and aqueous extract on the activity of Phase II metabolizing enzyme, glutathione-S-transferase (GST) in rat liver. Unripe seeds methanolic showed the effective GST specific activity inhibition with an IC 50 of 115.05 μg/mL with maximum inhibition > 70%. These results suggest that areca nut extracts have the potential to prevent oxidative damage in normal cells due to their antioxidant characteristics.

Dietary supplementation of ferulic acid and ferulic acid ethyl ester induces quinone reductase and glutathione- S-transferase in rats

Ferulic acid ethyl ester (FAEE) and ferulic acid (FA) were fed to rats to determine in vivo efficacy in elevating selected phase II enzyme activities and antioxidant capacity. Male Sprague–Dawley rats were fed the AIN-93M control diet, or the control diet supplemented with 1% FA, 1% FAEE, or 0.1% FAEE for 2 weeks. Quinone reductase (QR), glutathione- S-transferase (GST), thioredoxin reductase (TxR) activities, and oxidised and reduced glutathione were determined for brain, lung, liver, kidney, intestine and colon tissues. Both FA and FAEE (1%) supplementation increased QR and GST specific activities in kidney and colon tissues by 23–38% relative to the control diet. FAEE (1%) supplementation also induced QR specific activity, by 1.46- and 1.27-fold over the control diet, in intestinal and lung tissue of animals, whereas FA did not. No effect of diet was observed on liver cytochrome P450-1A1 activity. These results demonstrate that dietary FA and FAEE induce QR activity in the colon, small intestine, lung, and kidney, and improve glutathione antioxidant status in the colon and intestine. Therefore, dietary FA and FAEE may elevate defences to oxidative- and xenobiotic-induced stress in vivo.

Inhibition of glutathione-S-transferase as a treatment strategy for multidrug resistance in childhood rhabdomyosarcoma

Multidrug resistance (MDR) is a common problem in the treatment of childhood rhabdomyosarcoma (RMS). A complete reversal of MDR is currently not possible. The aim of this study was to investigate the role of glutathione-S-transferase (GST) as mechanism of MDR in childhood RMS and to analyze possible reversal strategies. Female athymic mice underwent xenotransplantation with embryonal or alveolar RMS cells and were treated with vincristine. Gene expression analysis using Affymetrix HU-Gene 1.0 arrays revealed 2314 differentially expressed genes between the groups in alveolar RMS and 1387 in embryonal RMS. Ingenuity pathway analysis revealed a cluster of 5 overexpressed genes of the GST family in animals treated with vincristine, putative mediating the development of MDR. In order to analyze possible GST activity after chemotherapy with other commonly used drugs (doxorubicin, topotecan), cell culture experiments with alveolar and embryonal RMS cells were carried out. Specific GST activity was quantified using the clorodinitrobenzol conjugation with glutathione. Increased GST activity was found after incubation with cytotoxic agents in all cell lines. Highest induction of GST activity was found in embryonal RMS (up to 12-fold). After incubation with the GST inhibitors, tumor cell viability was decreased depending on the type of tumor cell and inhibitor used. We detected a novel mechanism for MDR in childhood RMS mediated via genes and proteins of the GST family. Reversal of these effects may be achieved by GST inhibitors in part. The GST family represents a promising target for further treatment strategies in childhood RMS.

Comparison of Glutathione S-transferase Activity and Concentration in Aflatoxin-Producing and their Non-Toxigenic Counterpart Isolates

In this study, two techniques were used to compare the specific activity and total concentration of mycelial glutathione S-transferase (GST) in fungal strains isolated from natural sources. The fungi identified as Aspergillus parasiticus and Aspergillus flavus have been divided into two groups based on their ability to produce aflatoxins. Altogether 26 fungi were isolated, among which 12 were capable of producing varying levels of aflatoxin and 14 were proved to be non-toxigenic. GST specific activity in mycelial preparation was measured spectrophotometrically using 2,1-chloro-2,4-dinitrobenzene as the substrate. The results showed that the mean GST activity in toxigenic isolates was 25.06 +/- 9.8 micromol/mg protein/min which was 2.8-fold greater than that measured in non-toxigenic isolates (8.84 +/- 5.5 micromol/mg protein/min). Moreover, the GST concentration was compared in toxigenic and non-toxigenic isolates using an Enzyme Linked Immunosorbent Assay based on antigen (fungal preparation) and antibody (antibody produced against fungal GST in rabbit). The results of ELISA showed that the mean GST level in toxigenic and non-toxigenic fungi was 1.17 +/- 0.55 and 0.40 +/- 0.24, respectively. These results further confirm that the aflatoxin production in the fungal strains is correlated with GST expression and using ELISA, it is possible to discriminate aflatoxin-producing fungi from their non-toxigenic counterparts.

The effect of temperature on glutathione S‐transferase activity and glutathione content in Alopecurus myosuroides (black grass) biotypes susceptible and resistant to herbicides

SummaryHerbicide‐resistant populations of Alopecurus myosuroides (black grass) have become widespread throughout the UK since the early 1980s. Previous observations in this laboratory have demonstrated that natural climatic fluctuations caused increases in endogenous glutathione S‐transferase (GST) enzyme activity in A. myosuroides plants as they mature, which is thought to be linked to herbicide resistance in this species. The present study has investigated the effects of plant growth at 10°C and 25°C, and reports GST specific activity and glutathione (GSH) pool size in resistant and susceptible A. myosuroides biotypes. Findings demonstrate differences in GST activity between resistant and susceptible populations, which are transient at lower growth temperatures. The GSH pool size was elevated at lower growth temperature in both biotypes. We speculate that these endogenous responses are part of a natural mechanism of acclimation to environmental change in this species and suggest that resistant plants are more able to adapt to environmental stress, as indicated in this instance by temperature change. These observations imply that the control of resistant A. myosuroides by graminicides may be more effective when applied at lower temperatures and at earlier growth stages.

Gene expressions and enzyme analyses in theSchizosaccharomyces pombe Δpap1transcription factor mutant exposed to Cd2+

The objective of this study was to investigate the role of the Pap1 transcription factor in response to long-term Cd(2+) stress. The Schizosaccharomyces pombe wild-type strain and the Deltapap1 mutant, treated with 0.5 mM CdSO(4), were used in antioxidant enzyme and gene expression experiments. The Deltapap1 mutant proved to be sensitive to Cd(2+) in the spot test assay, suggesting that the Pap1 transcription factor plays an important role in the response to Cd(2+) stress. The Cd(2+) uptake was the same in both strains. Determination of the superoxide level in the wild-type strain proved that superoxide was generated, suggesting that long-term Cd(2+) treatment could trigger oxidative stress. Furthermore, the Deltapap1 mutant displayed higher amounts of superoxide. These results were supported by the significantly lower amount of peroxide generated in the reaction catalyzed by superoxide dismutase (SOD). The Deltapap1 mutant had a significantly lower glutathione S-transferase specific activity than that of the wild-type strain during long-term Cd(2+) stress, caused by the lower GSH and sulfide assimilation. We have demonstrated that GST III activity was not induced by Cd(2+) stress in the Deltapap1 mutant. The overall low GST activity was not sufficient for the cell to eliminate Cd(2+) caused damage and could result in a Cd(2+)-sensitive phenotype of the Deltapap1 mutant. The RT-PCR and Northern blot experiments proved that gst2 was not induced either by short-term or by long-term Cd(2+) treatment. The SPCC965.06 (a putative K(+) ion channel subunit) gene expression increased, while the hmt1 (an ABC-type vacuolar transporter protein) expression decreased in both strains. No detectable alteration in the mRNA levels of, gpx1, hmt2, sod1, sod, and trx1 was observed. SOD enzyme analyses revealed that the absence of Pap1 protein could result in a lower SODs activity and affect the sulfate assimilation. This is the first report on the fact that the Pap1 transcription factor could play an important role in the cellular post-transcriptional/post-translational enzyme activity induction processes of SODs that occur in response to Cd(2+).

Glutathione dependent enzyme activities in the foot of three freshwater mussel species in the Sava river, Serbia

We investigated activities of glutathione peroxidase (GSH-Px), glutathione reductase (GR), and the phase II biotransformation enzyme glutathione-S-transferase (GST) in the foot of three freshwater mussel species: Unio pictorum (Up), Unio tumidus (Ut), and Sinanodonta woodiana (Sw) from the Sava River. Specific and total GSH-Px activity was lower in Sw than in Up and Ut. Total GR activity was higher in Up than in Sw. Specific GST activity was higher in Up than in Ut. Total GST activity was higher in Up than in Ut and Sw. Electrophoretic analysis of proteins shows species specifities between the investigated mussel species. Our study represents the first comprehensive report of the investigated glutathione-dependent enzyme activities in the foot of three freshwater mussel species from the Sava River, Serbia. .

Safening efficacy of halogenated acetals, ketals and amides and relationship between the structure and effect on glutathione and glutathione S-transferases in maize

Abstract Halogenated acetal, ketal and acetamide type molecules were synthesized and tested for their ability to alleviate toxicity of acetochlor to maize and differentially enhance the glutathione (GSH) content and glutathione S-transferase (GST) activity in shoots and roots of maize. Safening experiments revealed that the dichloroacetals were inactive, while dichloroketals were effective as safeners. The degree of induction of GSH levels and GST activity measured with CDNB and acetochlor substrates were not correlated with the protective effects observed. Since both the herbicide and the experimental safeners, as chemical stressors, induce specific GST activities, we can conclude that increased GST activities are not solely responsible for the safening effect. The protective efficacy of dichloroketal safeners does not seem to be associated with enhanced herbicide detoxication by glutathione conjugation.