Lower Glutathione S-transferase Activity Research Articles

Glutathione S-transferase activity facilitates rice tolerance to the barnyard grass root exudate DIMBOA

BackgroundIn paddy fields, the noxious weed barnyard grass secretes 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA) to interfere with rice growth. Rice is unable to synthesize DIMBOA. Rice cultivars with high or low levels of allelopathy may respond differently to DIMBOA.ResultsIn this study, we found that low concentrations of DIMBOA (≤ 0.06 mM) promoted seedling growth in allelopathic rice PI312777, while DIMBOA (≤ 0.08 mM) had no significant influence on the nonallelopathic rice Lemont. DIMBOA treatment caused changes in the expression of a large number of glutathione S-transferase (GST) proteins, which resulting in enrichment of the glutathione metabolic pathway. This pathway facilitates plant detoxification of heterologous substances. The basal levels of GST activity in Lemont were significantly higher than those in PI312777, while GST activity in PI312777 was slightly induced by increasing DIMBOA concentrations. Overexpression of GST genes (Os09g0367700 and Os01g0949800) in these two cultivars enhanced rice resistance to DIMBOA.ConclusionsTaken together, our results indicated that different rice accessions with different levels of allelopathy have variable tolerance to DIMBOA. Lemont had higher GST activity, which helped it tolerate DIMBOA, while PI312777 had lower GST activity that was more inducible. The enhancement of GST expression facilitates rice tolerance to DIMBOA toxins from barnyard grass root exudates.

Influence of 50 Hz electromagnetic frequency on oxidative stress and morphological characteristics in mosquito-borne filariasis Culex pipiens

• The larvae of Culex pipiens were exposed to EMF frequency (50 Hz). • The biochemical and morphological changes in Culex pipiens were estimated. • The larval body weight and total protein in EMF treated groups were significantly decreased compared to control. • Antioxidant enzymes activity in EMF treated groups were decreased significantly compared to the control. • Both 500 & 1000 mT caused distinct malformations to the larval body parts. The electromagnetic field (EMF) is a vital issue in research, but its use as an alternative technique for insect management is still in its beginnings. The study aimed to evaluate the effects of exposure to the electromagnetic field on the biochemical analysis and morphological characteristics in Culex pipiens . Therefore, the third instar larvae were exposed to EMF frequency (50 Hz) at different intensities (250, 500, 1000 mT) for 1 h during four successive days. After end exposure to EMF, the biochemical analysis, oxidative stress parameters, body weight, and morphological features were investigated. The results showed that larval body weight and total protein content were decreased significantly in all treated groups compared to controls. The total lipid content significantly decreased at 500 & 1000 mT exposure, while the treatment group exposed to EMF at 250 mT was not statistically different compared to control. At a high intensity of EMF 1000 mT all oxidative stress parameters; catalase (CAT) and Glutathione S-transferase (GST) activity and lipid peroxidation level (MDA) were decreased significantly compared to the control. On the other hand, at a low intensity (250 mT), CAT and GST activity was significantly increased, while MDA content was not statistically changed. Scanning electron microscopy showed that both 500 & 1000 mT caused distinct malformations to the larval body parts, mouthparts, thorax and abdomen with last abdominal structures. In conclusion, the results demonstrated that EMF exposure is a considerable stress factor that affects oxidative state and morphological features in mosquitoes and give hope that EMF will be used as an alternative method for Culex pipiens vector control.

Biomarkers of oxidative stress and cell damage in freshwater bivalves Diplodon parodizi exposed to landfill leachate.

Landfill is a public and environmental health problem; establishing and understanding methodologies to decrease its toxicity are thus necessary. Leachate samples were collected, at a sanitary landfill, immediately after the exit from the landfill, i.e. raw leachate (collection point A), after conventional treatment (point B) and after treatment by wetlands (point C). D. parodizi specimens were exposed to 3%, 10% and control (0%) dilutions of leachate from these collection points for 7days. Markers of antioxidant defences and cell damage were analysed. At point B, the gills of D. parodizi showed higher glutathione-S-transferase (GST) and glutathione reductase (GR) activity; the latter is a supplier of glutathione reductase (GSH). The low GST activity at point A was associated with the hormesis effect. Higher levels of superoxide dismutase (SOD), ethoxyresorufin-O-deethylase (EROD) and glutathione peroxidase (GPx) occurred at point A. Glucose-6-phosphate dehydrogenase (G6PDH) was inhibited at the points with the highest pollutant load and at the highest leachate dilutions. Higher levels of markers at point A may be related to the high pollutant charge and specific compounds present in the untreated leachate. The multi-xenobiotic resistance mechanism (MXR), metallothionein-like proteins (MT) and lipid peroxidation (LPO) did not vary among treatments. The biomarker responses showed negative effects of the leachate on the freshwater bivalve and simultaneously showed that the wetland treatment employed at the Caximba sanitary landfill is effective.

Effects of pH on growth and biochemical responses in Agarophyton vermiculophyllum under different temperature conditions

The effects of pH (6.2, 7.2, 8.2, 9.2, and 10.2) under rising temperature (30 °C vs 20 °C) on Agarophyton vermiculophyllum growth and bio-physiology were investigated. Results showed that A. vermiculophyllum exhibited lower growth rates under elevated temperature in all pH values. Chlorophyll a, carotenoid, and phycocyanin levels were significantly enhanced by temperature elevation (p < 0.05). Enhanced H2O2 production either at lower or higher pH values correlated with lipid peroxidation (LPO) levels under elevated temperature, which suggested oxidative stress development. Oxidative damage was more severe at elevated pH values, which is confirmed by higher reactive oxygen species (ROS) levels. Compared with ambient pH 8.2 value, lower pH values under elevated temperature lead to increase activities of superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST), indicating that these enzymes played an important role to combat stress. However, decreased glutathione reductase (GR) and glutathione peroxidase (GPx) activities indicate least contribution for ROS scavenging at lower pH values. On contrary, SOD and CAT declined at elevated pH values compared with ambient pH, suggesting least contribution for ROS removal. Moreover, enhanced GR and GPx activities at elevated pH and temperature are not enough to scavenge ROS production. These data are consistent with higher H2O2 and LPO levels, and lower GST activities. Collectively, our results indicated that either pH fluctuations or elevated temperature displayed a disadvantageous influence on growth and bio-physiology of A. vermiculophyllum. Therefore, rising temperature alleviates adverse effects of seawater acidification, but it aggravates the negative effects of seawater alkalization on growth and bio-physiology of A. vermiculophyllum.

Human Adenovirus, Mesophilic Bacteria and Fungi in Puppies’ Food Marketed in Bulk in Southern Brazil

Background: The Brazilian domestic canine population are the second largest in the world and their feeding means 0.4% of the Brazilian gross domestic product. For maintaining the quality of the food, the companies use worldwide standards for technical prevention and control of contaminants and biological conservation. The packaging is part of this process, since it provides a barrier between food and environment. However, in Brazil, packagings are often opened in retail stores for bulk marketing. The objectives of this work were to develop a methodology to detect viruses in foods and to analyze the bacterial and fungal contamination in puppies’ food sold in bulk in Ivoti and Estância Velha, cities in Southern Brazil. Materials &amp; Methods &amp; Results: Twenty samples collected between September and October 2016 were analyzed for most probable number of coliforms, Salmonella sp., mesophilic aerobic bacteria and yeast/mold following the regulation of the Brazilian Ministry of Agriculture, Livestock and Food Supply guidelines. They were also tested for Human Mastadenovirus C (HAdV), Canine Mastadenovirus A (CAdV), and Carnivore Protoparvovirus 1 (CPV) genomes. Viral analysis were performed by polymerase chain reaction (PCR) detection. During the collection of the samples hygienic-sanitary conditions, storage of feeds, animals’ access, dog grooming, and veterinary care were considered to evaluate the conditions of each store. A pilot study was carried out using one food sample marketed in bulk and one sample from the original package (closed package) and testing them for bacterial and fungal contamination for standardizing viral detection. Ten grams of food from the original package were mixed with 90 mL of Eagles’ Minimal Essential Medium (E-MEM) in 100 mL sterile bottles. These bottles were kept in room temperature and shaken for 60 min. Subsequently, aliquots were obtained by sequentially diluting the sample (10-2 to 10-4). All final specimens contained 10 mL and each diluted sample was spiked with HAdV-C prototype viral strain (AdV5). A standard solution of HAdV-C was diluted from 3.6x106TCID50mL, (50% tissue culture infective dose) to 3.6x103 TCID50mL, and DNA extraction was performed. Nested-PCR targeting AdV DNApol was performed to detect adenoviruses from different hosts. AdV-positive samples were submitted to nucleotide sequencing and phylogenetic analysis. Specific PCRs were also carried out for CAdV and CPV. Mesophilic aerobic bacteria were detected in all samples and Aspergillus sp. was found in five samples, among which one sample was co-infected with Penicillium sp. One sample was positive for AdV, which was identified as HAdV by sequencing; while coliforms and Salmonella sp. were not detected.Discussion: The presence of fungi with mycotoxigenic potential, such as Aspergillus sp. and Penicillium sp. represents a threat for canines, due to toxins that may persist for a long period even after the fungus is not viable. Moreover, dogs seem to be more susceptible to the effects of the toxins, which is probably because of low glutathione s-transferase activity. Some species of Penicillium sp. genus may produce ocrathoxin A, which nephrotoxic and immunosuppressive effects in dogs are widely reported. Mesophilic bacteria were detected in all samples (at 104 CFU/g) and considered harmless. The detection of human viruses points to the presence of anthropic contamination; on the other hand, ingestion of contaminated feed, even if it is by a heterologous species, turns the dogs into carriers of the virus. In addition, manipulation of those feeds by children who share the same space with dogs can result in gastroenteritis episodes.

Biochemical and molecular biomarkers in integument biopsies of free-ranging coastal bottlenose dolphins from southern Brazil

Adverse effects of exposure to persistent organic pollutants (POPs) threaten the maintenance of odontocete populations. In southern Brazil, coastal bottlenose dolphins from the Laguna Estuarine System (LES) and Patos Lagoon Estuary (PLE) were sampled using remote biopsies during the winter and summer months. Levels of bioaccumulated POPs were measured in the blubber. The activities of glutathione S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx), and superoxide dismutase (SOD) were also quantified, as were the mRNA transcript levels of aryl hydrocarbon receptor (AhR), AhR nuclear translocator (ARNT), cytochrome P450 1A1-like (CYP1A1), metallothionein 2A (MT2A), GST-π, GPx-4, GR, interleukin 1 alpha (IL-1α), and major histocompatibility complex II (MHCII) in the skin. In general, levels of POPs were similar among sites, sexes, ages and seasons. For most animals, total polychlorinated biphenyl (ΣPCBs) levels were above the threshold level have physiological effects and pose risks to cetaceans. The best-fitting generalized linear models (GLMs) found significant associations between GR, IL-1α and GPx-4 transcript levels, SOD and GST activities, and total polybrominated diphenyl ether (ΣPBDEs) and pesticide levels. GLMs and Kruskal-Wallis analyses also indicated that there were higher transcript levels for most genes and lower GST activity in the winter. These results reinforce the need to consider the influence of environmental traits on biomarker values in wildlife assessments.

The activity of erythrocyte and platelet glutathione reductase and glutathione-S-transferase in paranoid schizophrenia

A comparative evaluation of glutathione reductase (GR) and glutathione-S-transferase (GST) activities in erythrocytes and platelets of patients with schizophrenia. Fifty patients, 47 men and 3 women, aged 25-56 years (medium 34) with acute paranoid schizophrenia (F20.0 ICD-10) with hallucinatory-paranoid or paranoid syndrome were studied. The control group consisted of 48 healthy people, 45 men and 3 women, aged 21-59 years (medium 38). GR activity was determined by the oxidation of NADP-H in the reduction reaction of oxidized glutathione. GST activity was determined by the rate of chromogenic conjugate formation between glutathione and 1-chloro-2.4-dinitrobenzene. No differences in the erythrocyte GR and GST activities between the control group and patients with schizophrenia were found. The platelet activity of GR and GST was significantly lower in patients compared to the control group (Mann-Whitney U test, p<0.01). Spearman rank correlation analysis showed that the erythrocyte GST activity was significantly correlated with PANSSneg scores when measured at the beginning of the study, GST was higher in those patients who had less PANSSneg scores after treatment (R=-0.41, p<0.05). The activity of platelet GST in patients with schizophrenia was correlated with the severity of positive symptoms (PANSSpos score) at the beginning of the study before taking therapy (R=-0.31, p<0.05), i.e. the more prominent psychotic symptoms were expressed in patients with lower GST activity. Upon completion of therapy, this association disappeared. The activity of glutathione-dependent enzymes in the blood cells of schizophrenic patients determined before the beginning of antipsychotic pharmacotherapy may be important for objective assessment of this metabolic system status and the degree of its impairment in patients.

Efficient Two-Photon Fluorescent Probe for Glutathione S-Transferase Detection and Imaging in Drug-Induced Liver Injury Sample.

Drug-induced liver injury (DILI) is a potential complication of any prescribed medication. So far, the diagnosis of DILI is still a clinical challenge due to the lack of efficient diagnosis method. Glutathione S-transferase (GST), with a high concentration in liver cytosol, can reduce toxicity and facilitate urinary excretion by catalyzing the conjugation of glutathione (GSH) with reactive metabolites in liver. When liver is seriously damaged, GST and GSH will be released into plasma from liver cytosol, which caused a lower GST activity in liver cytosol. Therefore, monitoring the level of GST activity in liver tissue may be a potential strategy for diagnosis of DILI. Here, we reported a two-photon probe P-GST for GST activity detection for the first time. In the proposed design, a donor-π-acceptor (D-π-A) structured naphthalimide derivative with efficient two-photon properties was chosen as the fluorescent group, and a 2,4-dinitrobenzenesulfonate group was employed as the GST recognition unit, which also acted as the fluorescence quencher. In the present of GST and GSH, the recognition unit was removed and the fluorophore was released, causing a 40-fold enhancement of fluorescence signal with a detection limit of 35 ng/mL. At last, P-GST was successfully applied in two-photon imaging of GST in cells and DILI samples, which demonstrated its practical application in complex biosystems as a potential method for diagnosis of DILI.

Variations in hepatic biomarkers in American alligators (Alligator mississippiensis) from three sites in Florida, USA

Sub-individual biomarkers are sub-lethal biological responses commonly used in the assessment of wildlife exposure to environmental contaminants. In this study, we examined the activity of glutathione-s-transferase (GST) and lactate dehydrogenase (LDH), and metallothionein (MT) concentrations among captive-raised alligator hatchlings, wild-caught juveniles, and wild-caught adults. Juveniles and adults were collected from three locations in Florida (USA) with varying degrees of contamination (i.e. Lake Apopka (organochlorine polluted site), Merritt Island National Wildlife Refuge (NWR) (metal polluted site), and Lake Woodruff NWR (reference site)). We examined whether changes in the response of these three biomarkers were age and sex dependent or reflected site-specific variations of environmental contaminants. Juvenile alligators from Merritt Island NWR had higher MT concentrations and lower GST activity compared to those from the other two sites. This outcome was consistent with higher metal pollution at this location. Sexually dimorphic patterns of MT and GST (F > M) were observed in juvenile alligators from all sites, although this pattern was not observed in adults. GST activity was lower in captive-raised alligators from Lake Apopka and Merritt Island NWR as compared to animals from Lake Woodruff NWR, suggesting a possible developmental modulator at these sites. No clear patterns were observed in LDH activity. We concluded that GST and MT demonstrate age and sex specific patterns in the alligators inhabiting these study sites and that the observed variation among sites could be due to differences in contaminant exposure.

Differential metabolism of 4-hydroxynonenal in liver, lung and brain of mice and rats

The lipid peroxidation end-product 4-hydroxynonenal (4-HNE) is generated in tissues during oxidative stress. As a reactive aldehyde, it forms Michael adducts with nucleophiles, a process that disrupts cellular functioning. Liver, lung and brain are highly sensitive to xenobiotic-induced oxidative stress and readily generate 4-HNE. In the present studies, we compared 4-HNE metabolism in these tissues, a process that protects against tissue injury. 4-HNE was degraded slowly in total homogenates and S9 fractions of mouse liver, lung and brain. In liver, but not lung or brain, NAD(P)+ and NAD(P)H markedly stimulated 4-HNE metabolism. Similar results were observed in rat S9 fractions from these tissues. In liver, lung and brain S9 fractions, 4-HNE formed protein adducts. When NADH was used to stimulate 4-HNE metabolism, the formation of protein adducts was suppressed in liver, but not lung or brain. In both mouse and rat tissues, 4-HNE was also metabolized by glutathione S-transferases. The greatest activity was noted in livers of mice and in lungs of rats; relatively low glutathione S-transferase activity was detected in brain. In mouse hepatocytes, 4-HNE was rapidly taken up and metabolized. Simultaneously, 4-HNE-protein adducts were formed, suggesting that 4-HNE metabolism in intact cells does not prevent protein modifications. These data demonstrate that, in contrast to liver, lung and brain have a limited capacity to metabolize 4-HNE. The persistence of 4-HNE in these tissues may increase the likelihood of tissue injury during oxidative stress.

A key role for an impaired detoxification mechanism in the etiology and severity of autism spectrum disorders.

BackgroundAutism Spectrum Disorders (ASD) is a syndrome with a number of etiologies and different mechanisms that lead to abnormal development. The identification of autism biomarkers in patients with different degrees of clinical presentation (i.e., mild, moderate and severe) will give greater insight into the pathogenesis of this disease and will enable effective early diagnostic strategies and treatments for this disorder.MethodsIn this study, the concentration of two toxic heavy metals, lead (Pb) and mercury (Hg), were measured in red blood cells, while glutathione-s-transferase (GST) and vitamin E, as enzymatic and non-enzymatic antioxidants, respectively, were measured in the plasma of subgroups of autistic patients with different Social Responsiveness Scale (SRS) and Childhood Autism Rating Scale (CARS) scores. The results were compared to age- and gender-matched healthy controls.ResultsThe obtained data showed that the patients with autism spectrum disorder had significantly higher Pb and Hg levels and lower GST activity and vitamin E concentrations compared with the controls. The levels of heavy metals (Hg and Pb), GST and vitamin E were correlated with the severity of the social and cognitive impairment measures (SRS and CARS). Receiver Operating Characteristics (ROC) analysis and predictiveness curves indicated that the four parameters show satisfactory sensitivity, very high specificity and excellent predictiveness. Multiple regression analyses confirmed that higher levels of Hg and Pb, together with lower levels of GST and vitamin E, can be used to predict social and cognitive impairment in patients with autism spectrum disorders.ConclusionThis study confirms earlier studies that implicate toxic metal accumulation as a consequence of impaired detoxification in autism and provides insight into the etiological mechanism of autism.

Protein damage from electrophiles and oxidants in lungs of mice chronically exposed to the tumor promoter butylated hydroxytoluene

The food additive butylated hydroxytoluene (BHT) promotes tumorigenesis in mouse lung. Chronic BHT exposure is accompanied by pulmonary inflammation and several studies indicate that elevated levels of reactive oxygen species (ROS) are involved in its promoting activity. The link between BHT and elevated ROS involves formation of quinone methide (QM) metabolites; these electrophiles form adducts with a variety of lung proteins including several enzymes that protect cells from oxidative stress. Studies in vitro demonstrated that QM alkylation of cytoprotective enzymes is accompanied by inactivation, so an objective of the present investigation was to determine if inactivation also occurs in vivo. Two groups of mice were exposed to BHT by intraperitoneal injection, one for 10 days and the other for 24 days, and proteins from lung cytosols were examined for damage. Analysis by Western blotting demonstrated that BHT treatment caused substantial increases in protein carbonylation, nitration and adduction by 4-hydroxynonenal, confirming the occurrence of sustained oxidative and nitrosative stress over the treatment period required for tumor promotion. Effects of BHT on the activities and/or levels of a representative group of antioxidant/protective enzymes in mouse lung also were assessed; NAD(P)H:quinone reductase and glutathione reductase were unaffected, however carbonyl reductase activity decreased 50–60%. Superoxide dismutase and glutathione peroxidase activities increased 2- and 1.5-fold, respectively, and glutamate-cysteine ligase catalytic subunit expression increased 32–39% relative to untreated mice. Glutathione S-transferase (GST) activity decreased 50–60% but concentrations of the predominant isoforms, GSTM1 and P1, were not affected. GSTP1 was substantially more susceptible than M1 to adduction and inhibition by treatment with BHT–QM in vitro, suggesting that lower GST activity in mice after BHT treatment is due to adduction of the P1 isoform. The results of this study provide additional insight into mechanisms of BHT-induced oxidative damage and further support a link between inflammation and tumor promotion in mouse lung.

Variation in glutathione status associated with induction and initiation of diapause in eggs of the bivoltine strain of the silkworm Bombyx mori

For the bivoltine (Dazao) strain of the silkworm Bombyx mori L., diapause expression in progeny is induced by exposure to conditions of 25 °C and continuous illumination (LL) during the maternal generation, whereas an environment of 15 °C and constant darkness (DD) results in nondiapause progeny. Initiation of diapause in progeny can be prevented by treatment of diapause‐programmed eggs with hydrochloric acid (HCl) at approximately 24 h post‐oviposition. To investigate whether glutathione is involved in the regulation of diapause induction and initiation in this species, measurements of total glutathione, reduced glutathione (GSH), oxidised glutathione (GSSG), GSH/GSSG ratio, glutathione S‐transferase (GST) and peroxiredoxins (Prdx) are compared in eggs incubated under LL and DD conditions, and between diapause eggs and those treated with HCl. Compared with DD, eggs incubated under LL have higher total glutathione (GSH + 2GSSG), lower GSH, higher GSSG, a lower GSH/GSSG ratio, lower GST activity and higher Prdx activity at stages 20–25 of maternal embryogenesis. The lower ratio of GSH/GSSG is indicative of pro‐oxidative conditions during diapause induction, which may result from the stronger oxidation of GSH. Compared with HCl‐treated eggs, diapause eggs have lower total glutathione, no difference in GSH, lower GSSG, a higher GSH/GSSG ratio, no difference in GST activity and lower Prdx between 36 and 72 h post‐oviposition. The higher ratio GSH/GSSG is indicative of reducing conditions during diapause initiation, which may a result of the weaker oxidation of GSH. Moreover, variations of Prdx and GST suggest that Prdx rather than GST plays an important role in the oxidation of GSH during the induction and initiation of diapause.

Regulation of oxidative stress in response to acute aerobic and resistance exercise in HIV-infected subjects: a case–control study

Human immunodeficiency virus (HIV)-infected subjects have increased levels of oxidative stress which could impair immunological function and therefore contribute to the progression of AIDS. These characteristics are usually evaluated at rest and responses to exercise have yet to be evaluated. The aim of the present study was to assess the effect of a bout of aerobic exercise followed by resistance exercises on antioxidant system in HIV-infected and non-HIV subjects. There were included 14 cases (HIV-positive) and 14 controls (HIV-negative). The exercise protocol consisted of a single session of 20 minutes on a cycloergometer followed by a set of six resistance exercises. The activity of glutathione S-transferase (GST) and catalase were measured in plasma samples, total glutathione (TGSH) and thiobarbituric acid reactive substances (TBARS) were measured in erythrocytes. T CD4+ cells, T CD8+, viral load, complete blood count, and white blood count were also assessed. All measurements were performed at three times: baseline, after aerobic exercise, and after resistance exercises. At baseline, the HIV group had lower GST activity than controls, but after the exercise session GST values were similar in both groups. Compared to the control group TGSH was significantly lower in the HIV group at baseline, after aerobic and resistance exercises. The control group presented higher TBARS values after aerobic exercise compared to the HIV group. The neutrophil count was lower in the HIV group after aerobic and resistance exercises. These data indicate that HIV-infected subjects had lower antioxidant activity at rest. Physical exercise stimulated the enzymatic activity similarly in both groups.

A study on the effects of food quantity and quality on glutathione S-transferase (GST) activity and growth rate parameters of Daphnia carinata varying in age

The adverse influences of insufficient food and toxins on Daphnia carinata's body growth, reproduction and tolerance were investigated in the laboratory. Different concentrations of Scendesmus obliquus and a mixture of S. obliquus and microcystin (MC)-containing Microcystis aeruginosa PCC7820 were used to feed D. carinata. Glutathione S-transferase (GST) activity towards five chemical compounds (substrates) was measured and used as an indicator of their tolerance. Body growth rate and clutch size of D. carinata decreased with declined concentration or decreased proportion of S. obliquus in the diet. GST activity decreased with ageing in D. carinata. However, GST activity to several chemical compounds increased when food quantity or food quality decreased. Adult D. carinata had a lower GST activity towards p-nitrophenenzyl chloride (PNBC) than juveniles and exhibited a sharp decline (P < 0.001) in GST activity towards PNBC as the animals aged. It is suggested that the age-specific decrease in GST activity is a possible mechanism for the high morality of adult D. carinata in the summer of eutrophic lakes.

Glutathione S-transferase phenotypes in relation to genetic variation and fruit and vegetable consumption in an endoscopy-based population

High glutathione S-transferase (GST) activity may contribute to colorectal cancer prevention. Functional polymorphisms are known in the GSTM1, GSTT1, GSTA1 and GSTP1 genes. The influence of these GST polymorphisms and recent fruit and vegetable consumption on GST levels and activity has not been investigated simultaneously in a human population. Also, it is not clear if blood GST activity reflects rectal GST activity. Therefore, we determined GST polymorphisms in 94 patients scheduled for sigmoidoscopy. Rectal GST isoenzyme levels (GSTM1, GSTM2, GSTT1, GSTA and GSTP1) were measured by quantitative western blotting, and rectal and white blood cell total GST activities were measured spectrophotometrically using 1-chloro-2,4-dinitrobenzene (CDNB) as a substrate. Vegetable and fruit consumption was assessed by dietary record. As expected, the GSTM1 and GSTT1 deletion polymorphisms, and the GSTA1 g.-69C-->T polymorphism significantly affected the respective isoenzyme levels. Also, rectal GST isoenzyme levels differed between those with and without recent consumption of Alliaceae, Cucurbitaceae, Apiaceae and citrus fruit. Rectal GST activity, however, was not clearly influenced by fruit and vegetable consumption. It was most significantly determined by the GSTP1 c.313A-->G polymorphism; compared with the 313AA genotypes, the 313AG and 313GG genotypes showed 36 and 67 nmol/min/mg protein (P < 0.001) lower GST activity, respectively. The correlation between rectal and white blood cell GST activities was low (r = 0.40, P < 0.001), and the relevance of the various genetic and dietary factors appeared to differ between the two tissues. In conclusion, this study indicates that the GST enzyme system is influenced by both GST polymorphisms and consumption of fruits and vegetables. The latter appeared more important for individual rectal GST isoenzyme levels than for total GST activity, which could affect detoxification of isoenzyme-specific substrates. The study results do no support the use of white blood cell GST activity as a surrogate measure for rectal GST activity.

Biochemical biomarkers in gills of mangrove oyster Crassostrea rhizophorae from three Brazilian estuaries

Responses of biochemical biomarkers were evaluated in gills of immature adult mangrove oyster Crassostrea rhizophorae collected in three estuarine regions along the Brazilian coast. In each region, ten oysters were collected in one reference site (R) located far from pollution sources, and in two polluted sites (P-I and P-II sites) located in another water body with similar characteristics. P-I site is located close to recognized pollution sources while P-II site is in the same water body, but far from pollution sources. At the Paranaguá Bay (Southern Brazil), polluted sites receive domestic, harbor and phosphate fertilizer plant discharges. High lipid peroxides (LPO) content was observed in winter oysters from the P-I site. In summer, higher catalase activity was observed in these oysters. In the Piraquê region (Southeastern Brazil), polluted sites receive domestic and agricultural effluents. Lower total oxyradical scavenging capacity (TOSC) towards peroxyradicals was observed in summer oysters from both P-I and P-II sites. In the Itamaracá region (Northeastern Brazil), polluted sites receive paper mill and caustic soda and chlorine factories effluents. Increased glutathione S-transferase (GST) activity was observed in oysters from the P-I site in both summer and winter. At Paranaguá Bay (higher latitude), no seasonal differences were observed in oysters from the R site, suggesting that temperature was not an important factor influencing biomarkers levels. Lower GST activity was observed in oysters from the R site of the Itamaracá Bay (lower latitude) in winter and summer. Taken together, data obtained point to responses of biomarkers in oysters from polluted sites of the three estuarine regions analyzed, indicating the need for future monitoring of the biological effects of contaminants in these environments. They also point to the relevance to consider both season and latitude as factors influencing biomarker responses in environmental contamination monitoring programs.

Alteration of Cytochrome P-450 and Glutathione S-Transferase Activity in Normal and Malignant Human Stomach

Cytochrome P-450 and glutathione S-transferase (GST) activities were investigated in stomach tumor and tumor-adjacent tissues of patients (n = 211) with gastric adenocarcinoma, and in the stomach tissues of unaffected individuals (normal tissues, n = 113). A significant reduction in total cytochrome P-450 activity was observed in tumor and tumor-adjacent tissues versus normal stomach. In all cases, cytochrome P-450 activity was significantly higher in males than in females. In the case of smokers, cytochrome P-450 activity was 1.8-fold higher in tumor-adjacent than in corresponding tumor tissues, but no difference was observed in nonsmokers. Patients had significantly lower GST activity in tumor and tumor-adjacent tissues compared to normal tissues. Smokers showed lower GST activity in both tumor and tumor-adjacent tissues compared to nonsmokers. In addition, GST activity was significantly lower in tissues positive for Helicobacter pylori infection than in H. pylori-negative tissues. However, the frequency of H. pylori infection was higher in tumor-adjacent (69%) than in tumor (45%) or normal tissues (44%). Our data suggest that diminished GST enzymes activity and increased cytochrome P-450 activity in normal and tumor-adjacent tissues might be due to the direct effect of the H. pylori infection and cigarette smoking, respectively. Data indicate that alterations in the activities of cytochrome P450 and GST may in part be associated with an increased risk for gastric cancer. This work was supported by the Brain Korea 21 project in 2003.

Biochemical indicators of contaminant exposure in spotted pigfish (Orthopristis ruber) caught at three bays of Rio de Janeiro coast

The initial sampling in the Marine Monitoring Program (MOMAM), coordinated by the Ministry of Marine Affairs (IEAPM), was performed along the southeast coast of Brazil. Orthopristis ruber samples were collected at Guanabara, Sepetiba and Ilha Grande Bays. Microsomal CYP1A levels and cytosolic cholinesterase (ChE), catalase (CAT) and glutathione S-transferase (GST) activities were measured in the liver of these fish according to established procedures. CAT activity and CYP1A content were significantly higher (P⩽0.05) in fish caught at Guanabara Bay, which might be due to higher levels of peroxisome proliferators and Ah receptor agonists, respectively, at this site compared to the other sites. Also, lower GST activity was observed in fish from this site, which may possibly be related to the presence of oxidative-stress inducing compounds.

Alterations of plasma antioxidants and mitochondrial DNA mutation in hair follicles of smokers.

The effects of long-term smoking on mitochondrial DNA (mtDNA) deletions in hair follicles were investigated in subjects with different antioxidant capacity. Twenty-two male smokers with a smoking index of greater than 5 pack-years and without any known systemic diseases were recruited for this study. Forty healthy nonsmoking males were included as controls. We found that the concentrations of ascorbate and alpha-tocopherol and the activities of glutathione S-transferase (GST) and glutathione peroxidase in blood plasma were significantly decreased in smokers. The levels of glutathione and protein thiols in whole blood and the incidence of a 4,977 bp deletion of mtDNA (dmtDNA) in hair follicles were significantly increased in smokers. A significantly higher incidence of the 4,977 bp dmtDNA was found in smokers with plasma GST activity less than 5.66 U/l (OR = 7.2, P = 0.020). Using multiple covariate ANOVA and logistic regression, we found that age and low plasma GST activity were the only two risk factors for the 4,977 bp dmtDNA. These results suggest that smoking depletes antioxidants and causes mtDNA deletions and that plasma GST may play an important role in the preservation of the mitochondrial genome in tissue cells of smokers.