Levels Of 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.

Copper and chlorpyrifos stress affect the gut microbiota of chironomid larvae (Propsilocerus akamusi).

Chironomids are characterized by their ubiquitous distribution, global diversity and tolerant ability to deal with environmental stressors. To our knowledge, this is the first study presenting the gut microbial structure of chironomid larvae and examining the microbial alteration induced by invading chlorpyrifos and copper with different dosages. Lethal bioassay displayed a significantly decreased percentage survival of Propsilocerus akamusi larvae exposed to 800mg/L copper and 50μg/L chlorpyrifos at 96h. Larvae with deficient gut microbiota exhibited a depressed level of glutathione S-transferase activity after stressful exposure. The high-throughput 16S rRNA gene sequencing was adopted to investigate the community structure and it turned out that both copper and chlorpyrifos were able to generate distinguished variations of gut microbiota in the stressor-specific and concentration-dependent manner. Of note, the relative abundance of Comamonas, Stenotrophomonas, and Yersinia remarkably elevated in the presence of copper while chlorpyrifos exposure upregulated the prevalence of certain genera (e.g. Serratia). Flavobacterium was greatly attenuated in chlorpyrifos group with lethal dosage exhibiting more severe impacts. The predicted gene functions of the gut commensals differed between normal samples and those subjected to distinct toxins. Besides, more positive associations and limited modularity of microbial interactions were observed in stressor-challenged larvae, presenting a network with impaired complexity and stability. The appearance of either copper or chlorpyrifos exhibited strong positive correlations with genera belonging to Proteobacteria and Firmicutes. Collectively, this investigation introduces a general outline of gut microbiota obtained from chironomid individuals with latent adaptive tactics to nocuous factors (heavy metal and pesticide), which could build a fundamental basis for us to further explore the protective roles of chironomid gut bacterial colonizers in defending against aquatic contaminants.

Can antioxidant responses be induced by habitat fragmentation process?

Animal populations are increasingly forced to live in small residual natural or semi‐natural areas due to habitat loss and fragmentation. Here, the viability of populations is often compromised by intrinsic threat factors typical of small and isolated populations, such as inbreeding depression, genetic drift and environmental and demographic stochasticity. Under these circumstances, organisms may have low fitness due to inadequate physiological responses needed to face environmental challenges. However, few studies have investigated the relationship between habitat fragmentation and stress defences. In this study, we aimed to test whether an increase in the level of individual inbreeding produced an increase in the antioxidant system response. To this purpose, we genotyped 151 individuals of fire salamander Salamandra salamandra (Amphibia: Urodela) within five sampling populations, located in forest landscapes with different degree of fragmentation in northern Italy. For 113 individuals we also measured the glutathione‐S‐transferase (GST) and catalase (CAT) enzyme activity. Results showed a significant increase in individual GST activity for increasing levels of inbreeding, whereas no relationship was found for CAT. We also measured acetylcholinesterase to test the possible confounding effects of pesticides that might have occurred in fragmented landscapes with forests interspersed with agricultural areas. However, no difference in this enzyme activity was found among sampling populations. We argue that high levels of GST activity may be symptomatic of oxidative stress derived from inbreeding. An increased frequency of homozygous deleterious alleles due to inbreeding may cause homeostatic alterations and trigger the expression of GST for protection against hydrogen peroxide reactive oxygen species. We suggest using GST as a biomarker for environmental stressors with great caution and not to underestimate that the sources of stress deriving from habitat fragmentation could lead to an unbalance in the oxidative status, possibly increasing population susceptibility to infectious diseases and, potentially, spillover events and zoonoses.

Expression and biochemical significance of Piwil2 in stem cell lines

Abstract Introduction P-element induced wimpy testis-like 2 (Piwil2) is in the Piwi gene family. Piwil2 has important roles in the self-renewal mechanism of stem cell induction and progression of numerous types of human malignancies such as lung, breast, colon, prostate, and cervical cancers. Glutathione S-transferase (GST) acts as detoxification in cancer metabolism. This study aimed to investigate the effects of the stem cell protein Piwil2 on MCF10A and MCF-7 at the GST activity levels. Materials/Methods MCF-7/Piwil2 and MCF10A/Piwil2, transfected with a plasmid carrying the Piwil2 gene, and non-transfected MCF-7 and MCF10A were cultured in a complete DMEM/F12 medium. GST A1 and P1 activity was determined in these cell lines using as substrates CDNB, EA respectively. Results According to experimental results, GST P1 activity decreased in the MCF-7/Piwil2 cells as compared with the non-transfected MCF-7 cells, however, MCF-7/Piwil2 cells demonstrated increases in GST A1 (total GST) activity. The statistically significant differences were found for the comparison of non-transfected MCF-7 and MCF-7/Piwil2 (p<0,0001), for GST enzyme activities by using CDNB and EA as substrates. These results were the same for the MCF10A cell line. Discussion It is shown for the first time that transfection studies may affect GST activity at the cellular mechanism level. The study contributes to determining the effect of transfection on GST isoenzymes and also how the Piwil2 gene may affect GST activity in the stem cell line.

Levels of glutathione-related antioxidants in some tissues of stressed Wistar rats

Objectives: Oxidative stress (OS)-related pathologic conditions in the tissues of living organism have been linked to exposure to stressful events within the environment. This study examined the impact of different kinds of stress exposure on glutathione (GSH)-related antioxidants. The effect of stress was examined using comparative levels of GSH, glutathione-S-transferase (GST) and glutathione peroxidase (GPx) in female Wistar rats. Materials and Methods: One hundred and sixty-eight adult female Wistar rats with body weights ranging between 150 and 200 g, were used for the study. The animals were distributed into 28 groups of six animals each. The experimental animals were routinely exposed to three different stressors; restraint chamber test, mirror chamber test and intruder chamber test for a duration of 1, 3 or 5 h per day for 1, 2 and 3 weeks, respectively. All animals were allowed free access to food (rat chaws), with water ad libitum. Animals were euthanise through cervical dislocation after the experimental period and the different target tissues were carefully harvested and homogenised for antioxidant estimation following standard procedure. Data obtained were statistically analysed and values expressed as mean ± standard error of mean and P < 0.05 level was considered as statistically significant. Results: Findings from this study elucidated the fact that exposure to stress is capable of causing marked OS and reducing GSH-based antioxidant activities in Wistar rats. A decline in the GSH level and GPx activity as observed in the study is an indication of alterations of kidney and brain tissue cellular integrity by free radicals generated during exposure to the stressors, while the observed significant increase in GST activity level in the affected tissues indicates compromised rapid exhaustion of the cellular system. Conclusion: Hence, we conclude that stress of different nature, intensity and duration can alter the levels of GSH-related antioxidants, especially in the kidney, ovary and brain tissues of stressed Wistar rats. The GSH levels in liver tissues were observed not to have changed significantly despite the oxidative damage caused by the stressors.

Near-infrared frequency upconversion probes for monitoring glutathione S-transferase to evaluate acute liver injury

Acute liver injury (ALI) is one of the main causes of malignant liver disease. We developed a rhodamine-based frequency upconversion luminescent probe (NRh-NNBA) to detect the biomarker glutathione S-transferase (GSTs) to monitor ALI. NRh-NNBA showed a rapid and specific response to GSTs in drug-induced and CCl4-induced ALI, respectively, by generating the enzymatic product NRh-glutathione, which emitted at 832 nm under excitation at 850 nm. NRh-NNBA successfully detected endogenous GSTs in human liver L02 cells with a high signal-to-noise ratio, and detected GSTs activity levels in liver slices and serum from ALI mice. These results suggest that NRh-NNBA might serve as an ideal sensor for monitoring GSTs during the diagnosis and treatment of ALI.

Effects of host plants on the population parameters and activities of detoxification enzymes in Laodelphax striatellus

AbstractThe small brown planthopper (SBPH), Laodelphax striatellus (Fallén) (Hemiptera: Delphacidae), is an economically important pest of rice (Oryza sativa L.), wheat (Triticum aestivum L.), and other members of the Poaceae. The effects of host plant type on SBPH life table parameters reared on two cultivars of rice (Zixiangnuo 2315 and Wuyujing 3), wheat (Jimai 22 and Nongda 26), and one grass weed (Echinochloa crusgalli Beauv.) under laboratory conditions were determined using the age‐stage, two‐sex life table. Additionally, the corresponding activities of three detoxifying enzymes – carboxylesterase (CarE), glutathione‐S‐transferase (GST), and mixed‐function oxidase (MFO) – were also measured. The results showed that host plant species and cultivars had effects on population parameters and activities of detoxification enzymes. Rice cv. Zixiangnuo 2315 and wheat cv. Nongda 26 were shown to be more suitable than the other three hosts. The activities of the three detoxifying enzymes showed different patterns of changes on the three host plants after feeding for 0–72 h. Regardless of short‐term (72 h) or long‐term (one generation) induction on host plants, the activity levels of GST and MFO in adult SBPH reared on rice ‘Zixiangnuo 2315’ were lower and higher, respectively, than on the other four hosts. The results may help understand the host adaptability of this pest and inform the development of strategies for effective field‐based integrated pest management programs.

Morphological and histological abnormalities of the neotropical toad, Rhinella arenarum (Anura: Bufonidae) larvae exposed to dexamethasone

Dexamethasone (DEX) is a glucocorticoid highly effective as an anti-inflammatory, immunosuppressant and decongestant drug. In the present study, a preliminary acute toxicity test was assayed in order to determinate DEX median-lethal, lowest-observed-effect and the no-observed-effect concentrations (LC50, LOEC and NOEC, respectively) on the common toad embryos (Rhinella arenarum). Also, morphological and histological abnormalities from five body larval regions, liver melanomacrophages (MM) and glutathione S-transferase (GST) activity were evaluated in the toad larvae to characterize the chronic sublethal effects of DEX (1–1,000 µg L−L). Results of the acute test showed that the LC50 of DEX at 96 h of exposure for the toad embryos (GS 18–20) was 10.720 mg L−g, and the LOEC was 1 µg L−g. In the chronic assay, the larval development and body length were significantly affected. DEX exposition also induced teratogenic effects. Most frequent external abnormalities observed in DEX-treated larvae included abdominal edema and swollen body, abnormal gut coiling and visceral congestion. Intestinal dysplasia was recurrent in cross-section of all DEX-treated larvae. Neural, conjunctive and renal epithelial cells were also affected. Significant increase in liver MM number and size, and GST activity levels were also registered in DEX treatments with respect to controls. The evaluation of a variety of biomarkers provided clear evidence of toad larvae sensitivity to DEX, and the ecotoxicological risk of these pharmaceuticals, commonly found in different water bodies worldwide on aquatic animals.

Glutathione S-transferase activity and genetic polymorphisms associated with exposure to organochloride pesticides in Todos Santos, BCS, Mexico: a preliminary study.

The objective of this study was to identify and evaluate the impact of exposure to mixtures of organochloride pesticides (OCPs) in agricultural workers by detecting their effects on the activity of the enzyme glutathione S-transferase (GST) and the presence of polymorphisms of the GSTT1 and GSTM1 genes. The presence of OCPs was identified and quantified by gas chromatography, while spectrophotometry was used to measure enzymatic GST activity. The frequencies of the GSTM1 genotypes were analyzed by multiplex PCR. A total of 18 metabolites of OCPs were identified in the workers' blood, most of which are either prohibited (DDT and its metabolites p, p'DDD and p, p'DDE, dieldrin, endrin, aldrin) and/or restricted (δ hexachlorocyclohexane, cis chlordane, methoxychlor, and endosulfan). The results obtained indicate lower levels of GST activity at higher OCPs concentrations detected in blood from exposed workers, together with an increase in OCP levels in individuals who presented the GSTT1*0 and GSTM1*0 genotypes. These conditions place the detoxification process in agricultural workers with null polymorphisms in the GST genes and high concentrations of OCPs in the blood (especially DDT and its metabolites, DDD and DDE) at risk, and increase their susceptibility to develop serious diseases.

Insecticide susceptibility of the sand fly leishmaniasis vector Phlebotomus argentipes in Sri Lanka

BackgroundLeishmania donovani-induced and sand fly-transmitted leishmaniasis is a growing health problem in Sri Lanka. Limited knowledge on biological and behavioral characteristics of probable vector Phlebotomus argentipes hinders disease control. Here, insecticide susceptibility patterns of P. argentipes were investigated with exploration of probable underlying resistance mechanisms.MethodsAdult sand flies were collected using standard cattle baited net traps and CDC light traps from selected sites in four districts. Adult F1 progeny of P. argentipes were exposed to different concentrations of DDT, malathion, deltamethrin and propoxur using WHO susceptibility bioassay kits. Post-1-h knockdown and post-24-h mortality were recorded and analyzed. Metabolic enzyme activity and the sensitivity of the acetylcholinesterase target-site were determined by biochemical assays using wild-caught flies. Extracted fly DNA samples were tested for the presence of knockdown-resistance (kdr) type mutations.ResultsThe LC100 values for DDT, malathion, propoxur and deltamethrin were 0.8–1.5%, 0.9–2.0%, 0.017–0.03% and 0.007% respectively. Insecticide-susceptibility levels were higher than the discriminating dosages established for Aedes mosquitoes, except for malathion. The lowest susceptibility levels (except for deltamethrin) were detected in the Mamadala population, whereas the highest levels were detected in the Mirigama population. The percentage of knocked-down sand flies was < 75% at any tested concentration, including those, which exhibited 100% mortality after 24 h. Elevated activity levels of glutathione S-transferase (3%, 7%, 12.5% and 14%) and esterase (2%, 5%, 5.5% and 6.5%) were detected in flies that originated from Mirigama, Pannala, Thalawa and Mamadala respectively, while monooxygenase quantities remained below the cut-off level. Ten to 34.5% of flies were heterozygous for acetylcholinesterases target-site insensitivity, associated with organophosphate and carbamate resistance. Pyrethroid-resistance-associated L1014F kdr-type mutation in the voltage gated sodium channel gene was detected in 30/53 flies.ConclusionsPopulations of P. argentipes in Sri Lanka are largely susceptible to common insecticides, except for malathion (used extensively in the past for malaria control). Their insecticide susceptibility appears negatively associated with past malaria endemicity of the study sites, with signs of early insecticide tolerance. Presence of insecticide target site insensitivity in a notable proportion of flies and enhanced insecticide metabolizing enzyme activities imply potential future challenges for leishmaniasis control, with a call for urgent proactive measures for its containment.

Acetylcholinesterase, Butyrylcholinesterase and Glutathione S-Transferase Enzyme Activities and Their Correlation with Genotypic Variations Based on GST M1 and GST T1 Loci in Long Term-Pesticide-Exposed Tea Garden Workers of Sub-Himalayan West Bengal

Organophosphates (OPs) and carbamates (CBs) are known to reduce acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) and increase Glutathione S-Transferase (GST) activities in the exposed individuals. We have evaluated AChE, BChE and GST activities in long-term pesticide exposed tea garden workers of sub-Himalayan West Bengal and tried to relate enzyme activities with polymorphisms in GST M1 and GST T1 genes. Enzyme activities were measured spectro-photometrically in blood samples of sprayers and pluckers in relation to age-matched control individuals. Allele-specific multiplex-PCR was employed to score the presence of GST M1 and GST T1 alleles. Significantly lower (p < 0.01) level of AChE and BChE activities were found in the worker group (3.15 ± 0.69 µmol/min/mL of lysate and 1.2 ± 0.54 µmol/min/mL of plasma respectively) compared to the control group (3.74±0.26 µmol/min/mL of lysate and 2.21 ±0.27 µmol/min/mL of plasma respectively). Whereas, significantly higher (p < 0.01) level of GST activity was detected in the worker group (3.83 ±0.97 lU/gm of Hb) comprising of 61 individuals compared to control group (2.47 ±0.29 lU/gm of Hb) comprising of equal number of individuals. Out of total 122 individuals, 34.43% had both GST M1 and GST T1, 23.77% had single-null genotype for GST T1, 27.05% had the single-null genotype for GST M1 and 14.75% individuals had double-null genotypes. We found no significant difference in enzyme activities among the four genotypes when test and control groups were compared. This study for the first time explored changes in AChE, BChE and GST activities in tea garden workers exposed chronically to OPs and CBs in the studied region. Our study indicated that exposure to OP and CB pesticides leads to changes in AChE, BChE and GST activities and the presence or absence of GST M1 and GST T1 alleles are possibly not related to the changes in AChE, BChE and GST activities.

Altered levels of GST activity, Vit C, TPX and Cu in individuals with long-term sulfur mustard-induced lung complications

Context: Sulfur mustard (SM) as a cytotoxic and blistering agent can alkylate a variety of cellular components, causing the incidence of ongoing oxidative stress.Objective: The present study was conducted to assess oxidative stress index (OSI) in SM-exposed veterans with long-term pulmonary complications.Methods: Participants consisted of 289 SM-exposed individuals with pulmonary complications (classified into three groups: mild, moderate and severe) and 66 healthy individuals as the control group. Enzymatic and non-enzymatic antioxidant and also trace elements were measured in the study groups. Moreover, some of oxidative stress indicators consist of malondialdehyde (MDA), protein carbonyl (CO), total antioxidant (TA) and total peroxide (TPX) were measured and then OSI was calculated.Results: Glutathione-S-transferase (GST) activity and vitamin C (Vit C) were significantly decreased in SM-exposed patients as compared with controls. Besides, Cu level and Cu/Zn ratio in SM-exposed veterans showed a significant correlation with the severity of the diseases. Serum TPX was significantly increased in SM-exposed individuals, as a result of which the OSI was slightly higher in them than controls. This can be considered as an indicative for oxidative stress in SM-exposed patients.Conclusion: This study suggests a particular role for TPX, Cu, Vit C and GST in SM-induced pulmonary complications. Therefore, a special attention should be paid to these factors in designing therapeutic protocols, which can reduce the progression risk of the disease.

Protective Effect of Rosa damascena Against Aluminum Chloride-Induced Oxidative Stress.

Aluminum is considered an essential element endowed with toxicity potentials in human and animal. Thus, intoxication with aluminum can lead to oxidative stress, which is associated with oxidative damage to various macromolecules. Moreover, antioxidants from natural sources can play an important role in human health. Accordingly, the purpose of this study was to investigate the protective effect of Rosa damascena extract against aluminum-induced oxidative stress. In this study, 60 male rats were randomly divided into six groups and then they were given daily aluminum chloride and Rosa damascena extract. After 8weeks of treatment, the levels of total antioxidant and malondialdehyde, as well as antioxidant enzymes including catalase, glutathione S-transferase, and myeloperoxidase, were measured in all experimental groups in this study. A significant increase was found in the total antioxidant level in the rats treated with aluminum, Rosa damascena extract, and aluminum plus Rosa damascena extract compared with those in the control group. Also, malondialdehyde levels were not significantly different in all the studied groups. Glutathione S-transferase activity levels in rats receiving the Rosa damascena extract as well as rats taking aluminum with Rosa damascena extract increased significantly compared with the ones in the control group. Catalase activity in the aluminum-treated group also increased significantly compared with the rates in the control group (31.34 ± 4.50U/gHb vs. 14.04 ± 6.17U/gHb, p = 0.014). Furthermore, myeloperoxidase activity in the aluminum-treated group increased significantly compared with the control group (49.47 ± 5.12U/L vs. 25.28 ± 2.18U/L, p < 0.001). The Rosa damascena extract could improve antioxidant capacity and reduce oxidative conditions in rats receiving aluminum chloride as evidenced by assays of the ferric reducing ability of plasma and activity of antioxidant enzymes. According to the findings of this study, it can be concluded that the Rosa damascena extract with its high antioxidant content is able to exert a protective effect against aluminum-induced oxidative stress.

High serum iron and zinc decrease glutathione S-transferase among women with breast cancer

BACKGROUNDBreast cancer in Indonesia ranks second as the most common cancer found in women after cervical cancer. Tumor cells express increased levels of antioxidant proteins to detoxify reactive oxygen species (ROS). Glutathione S-transferase (GST) is known to play a key role in the detoxification and reduction of ROS. Trace elements have nutritional benefits as essential cofactors for physiologic processes, but some can be toxic to humans. Accumulated evidence suggests that deficiency or excess of certain trace elements may be associated with risk of chronic diseases including cardiovascular diseases, diabetes and cancer. The aim of this research was to determine the correlation of the trace elements iron and zinc with the oxidative stress level of GST activity in women with breast cancer.METHODSAn observational analytic study with cross sectional design was conducted involving 35 breast cancer women. Research subjects were women with breast cancer diagnosed by biopsy. Measurements of iron and zinc levels were performed using atomic absorption spectrometry, GST activity was measured using spectrophotometry. Data analysis was done with the Pearson correlation test.RESULTSThe results showed that there was a significant relationship of serum iron with GST (r=-0.487; p&lt;0.05) and serum zinc with GST (r=-0.409; p&lt;0.01).CONCLUSIONOur study demonstrated that the higher zinc and iron level, the lower GST level among breast cancer women. It is recommended to use zinc, iron and GST levels as biomarkers for breast cancer and its progression.

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.

Acaricide susceptibility of Oligonychus coffeae Nietner (Acari: Tetranychidae) with corresponding changes in detoxifying enzyme levels from tea plantations of sub-Himalayan Terai, India

Oligonychus coffeae Nietner is cosmopolitan in its distribution and is an important pest of a number of economically important tropical and sub-tropical crops including tea. It is the most damaging acarine pest of tea crops in the sub-Himalayan Terai region of India which is mostly controlled chemically in the conventionally managed tea plantations of the region. Objectives of the present study were to i) investigate the tolerance level of O. coffeae collected from bio-organically managed plantations (BMP) (with no synthetic acaricide application) and conventionally managed plantations (CMP) (with periodic application of synthetic acaricide) to the acaricides, ’ethion’ and ’fenpropathrin’, ii) Quantify the detoxifying enzymes, general esterases (GE) of phase I and glutathione S-transferases (GST) of phase II, in O. coffeae as these are deemed important in acquiring pesticide tolerance, iii) Establish the relation of GE and GST activity levels with acaricide tolerance levels in populations of O. coffeae. The study revealed that i) BMP populations of O. coffeae were susceptible to both of the acaricides whereas CMP populations were tolerant. CMP populations of the pest showed low to medium tolerance to the organophosphate acaricide ’ethion’ whereas tolerance to the synthetic pyrethroid, ’fenpropathrin’ was high; ii) Corresponding GE and GST levels were significantly higher in CMP populations compared to that of BMP population. Electrophoretic analysis of GE isozymes of CMP and BMP populations further corroborated the quantitative study; iii) activity of the detoxifying enzymes, GE and GST were positively correlated with the tolerance level of O. coffeae populations indicating involvement of these enzymes in the development of acaricide tolerance.

Editor's Highlight: Glutathione S-Transferase Activity Moderates Methylmercury Toxicity During Development in Drosophila.

Glutathione (GSH) pathways play a central role in methylmercury (MeHg) metabolism and elimination, largely due to formation of a more readily transported MeHg-GSH conjugate. Glutathione S-transferases (GSTs) have therefore been proposed to facilitate MeHg elimination by catalyzing MeHg-GSH conjugation. A role for human GSTP1 in MeHg disposition is suggested by the association of two common polymorphisms in the coding region (Ile105Val and Ala114Val) with Hg levels in either blood or hair. In this study, we investigated a functional role for GSTs in modulating MeHg toxicity during development. Using the Drosophila model to execute targeted manipulations of both endogenous GSTs and introduced human GSTP1 variants we correlate gene and protein expression levels with GST activity and also with MeHg body burden and developmental outcomes. RNAi knockdown of endogenous GSTD1, GSTE1, or GSTS1, individually, increased susceptibility to MeHg during pupal development resulting in a reduced rate of adult eclosion. Exogenous expression of human GSTP1 in developing flies resulted in increased MeHg tolerance relative to control flies as seen with elevated eclosion rates when reared on MeHg containing food. Furthermore, the GSTP1105 and GSTP1114 variants showed a reduced enzyme activity relative to wild-type GSTP1 (GSTP1wt). Finally, we observed a trend whereby Hg body burden was inversely related to the levels of GST activity. However, in some instances GSTP1 expression resulted in increased eclosion rates without reducing Hg body burden suggesting that GSTs interact with MeHg via both toxicokinetic and toxicodynamic mechanisms. These findings indicate that GSTs moderate MeHg toxicity during development in our experimental model.

Development of a Fluorescence Probe for Live Cell Imaging

Probes that detect specific biological materials are indispensable tools for deepening our understanding of various cellular phenomena. In live cell imaging, the probe must emit fluorescence only when a specific substance is detected. In this paper, we introduce a new probe we developed for live cell imaging. Glutathione S-transferase (GST) activity is higher in tumor cells than in normal cells and is involved in the development of resistance to various anticancer drugs. We previously reported the development of a general strategy for the synthesis of probes for detection of GST enzymes, including fluorogenic, bioluminogenic, and 19F-NMR probes. Arylsulfonyl groups were used as caging groups during probe design. The fluorogenic probes were successfully used to quantitate very low levels of GST activity in cell extracts and were also successfully applied to the imaging of microsomal MGST1 activity in living cells. The bioluminogenic and 19F-NMR probes were able to detect GST activity in Escherichia coli cells. Oligonucleotide-templated reactions are powerful tools for nucleic acid sensing. This strategy exploits the target strand as a template for two functionalized probes and provides a simple molecular mechanism for multiple turnover reactions. We developed a nucleophilic aromatic substitution reaction-triggered fluorescent probe. The probe completed its reaction within 30 s of initiation and amplified the fluorescence signal from 0.5 pM target oligonucleotide by 1500 fold under isothermal conditions. Additionally, we applied the oligonucleotide-templated reaction for molecular releasing and peptide detection.

Enzymatic Activity of Glutathione S-Transferase and Dental Fluorosis Among Children Receiving Two Different Levels of Naturally Fluoridated Water.

This study was conducted to measure the activity of the enzyme glutathione S-transferase (GST) in saliva and to compare the activity of this enzyme in children with and without dental fluorosis in communities with different concentrations of naturally fluoridated water. A total of 141 schoolchildren participated in this cross-sectional study. Children were selected from two communities: one with a low (0.4ppm) and the other with a high (1.8ppm) water fluoride concentration. Dental fluorosis was evaluated by applying the Thylstrup and Fejerskov Index (TFI) criteria. Stimulated saliva was obtained, and fluoride concentration and GST activity were measured. The GST activity was compared among children with different levels of dental fluorosis using multinomial logistic regression models and odds ratios (OR). The mean age of the children was 10.6 (±1.03) years. Approximately half of the children showed dental fluorosis (52.5%). The average GST activity was 0.5678 (±0.1959) nmol/min/μg. A higher concentration of fluoride in the saliva was detected in children with a higher GST activity (p=0.039). A multinomial logistic regression model used to evaluate the GST activity and the dental fluorosis score identified a strong association between TFI=2-3 (OR=15.44, p=0.007) and TFI≥4 (OR=55.40, p=0.026) and the GST activity level, compared with children showing TFI=0-1, adjusted for age and sex. Schoolchildren with higher levels of dental fluorosis and a higher fluoride concentration in the saliva showed greater GST activity. The increased GST activity most likely was the result of the body's need to inactivate free radicals produced by exposure to fluoride.

Early habituation of maize (Zea mays) suspension-cultured cells to 2,6-dichlorobenzonitrile is associated with the enhancement of antioxidant status.

The cellulose biosynthesis inhibitor 2,6-dichlorobenzonitrile (DCB) has been widely used to gain insights into cell wall composition and architecture. Studies of changes during early habituation to DCB can provide information on mechanisms that allow tolerance/habituation to DCB. In this context, maize-cultured cells with a reduced amount of cellulose (∼20%) were obtained by stepwise habituation to low DCB concentrations. The results reported here attempt to elucidate the putative role of an antioxidant strategy during incipient habituation. The short-term exposure to DCB of non-habituated maize-cultured cells induced a substantial increase in oxidative damage. Concomitantly, short-term treated cells presented an increase in class III peroxidase and glutathione S-transferase activities and total glutathione content. Maize cells habituated to 0.3-1 µM DCB (incipient habituation) were characterized by a reduction in the relative cell growth rate, an enhancement of ascorbate peroxidase and class III peroxidase activities, and a net increment in total glutathione content. Moreover, these cell lines showed increased levels of glutathione S-transferase activity. Changes in antioxidant/conjugation status enabled 0.3 and 0.5 µM DCB-habituated cells to control lipid peroxidation levels, but this was not the case of maize cells habituated to 1 μM DCB, which despite showing an increased antioxidant capacity were not capable of reducing the oxidative damage to control levels. The results reported here confirm that exposure and incipient habituation of maize cells to DCB are associated with an enhancement in antioxidant/conjugation activities which could play a role in incipient DCB habituation of maize-cultured cells.