Activity Of GSTs Research Articles

Target gene overexpression and enhanced metabolism confer resistance to nicosulfuron in Eriochloa villosa (Thunb.)

Eriochloa villosa (Thunb.) Kunth is a troublesome weed widely distributed in maize (Zea mays L.) fields in Northeast China. Many populations of E. villosa have evolved resistance to nicosulfuron herbicides, which inhibit acetolactate synthase (ALS). The objectives of this research were to confirm that E. villosa is resistant to nicosulfuron and to investigate the basis of nicosulfuron resistance. Whole-plant dose–response studies revealed that the R population had not developed a high level of cross-resistance and exhibited greater resistant (25.62-fold) to nicosulfuron than that of the S population and had not yet developed a high level of cross-resistance. An in vitro ALS activity assay demonstrated that the I50 of nicosulfuron was 6.87-fold greater in the R population than the S population. However, based on ALS gene sequencing, the target ALS gene in the R population did not contain mutations. Quantitative real-time polymerase chain reaction (qRT–PCR) revealed that ALS gene expression between the R and S populations was significantly different after nicosulfuron application, but no differences were observed in the gene copy number. After the cytochrome P450 inhibitor malathion or the GST inhibitor NBD-Cl was applied, the resistant E. villosa population exhibited increased sensitivity to nicosulfuron. Based on the activities of GSTs and P450s, the activities of the R population were greater than those of the S population after nicosulfuron application. This is the first report that the resistance of E. villosa to ALS inhibitors results from increased target gene expression and increased metabolism. These findings provide a theoretical foundation for the effective control of herbicide-resistant E. villosa.

Rattus norvegicus Glutathione Transferase Omega 1 Localization in Oral Tissues and Interactions with Food Phytochemicals.

Glutathione transferases are xenobiotic-metabolizing enzymes with both glutathione-conjugation and ligandin roles. GSTs are present in chemosensory tissues and fluids of the nasal/oral cavities where they protect tissues from exogenous compounds, including food molecules. In the present study, we explored the presence of the omega-class glutathione transferase (GSTO1) in the rat oral cavity. Using immunohistochemistry, GSTO1 expression was found in taste bud cells of the tongue epithelium and buccal cells of the oral epithelium. Buccal and lingual extracts exhibited thiol-transferase activity (4.9 ± 0.1 and 1.8 ± 0.1 μM/s/mg, respectively). A slight reduction from 4.9 ± 0.1 to 4.2 ± 0.1 μM/s/mg (p < 0.05; Student's t test) was observed in the buccal extract with 100 μM GSTO1-IN-1, a specific inhibitor of GSTO1. RnGSTO1 exhibited the usual activities of omega GSTs, i.e., thiol-transferase (catalytic efficiency of 8.9 × 104 M-1·s-1), and phenacyl-glutathione reductase (catalytic efficiency of 8.9 × 105 M-1·s-1) activities, similar to human GSTO1. RnGSTO1 interacts with food phytochemicals, including bitter compounds such as luteolin (Ki = 3.3 ± 1.9 μM). Crystal structure analysis suggests that luteolin most probably binds to RnGSTO1 ligandin site. Our results suggest that GSTO1 could interact with food phytochemicals in the oral cavity.

Detoxification enzyme is involved in the temperature effect on the toxicity of tetrachlorantraniliprole to Plutella xylostella

The efficacy of insecticides is usually influenced by temperature. Insecticides can be divided into “positive”, “negative” and “non-effect” temperature coefficient insecticides (TCI). To assess the temperature-dependent effect of tetrachlorantraniliprole (TET) on Plutella xylostella Linnaeus and to elucidate the mechanism of temperature affects TET toxicity, we determined the toxicity of TET against P. xylostella from 15 °C to 35 °C by leaf dipping method. Moreover, we compared the transcriptome data of the third-instar larvae treated by TET, chlorfenapyr (CHL, non-effect TCI), and the control group at 15, 25, 35 °C, respectively. The results showed that the toxicity of TET against P. xylostella increased with increasing temperature from 15 °C to 35 °C. A total of 21 differential expressed genes (DEGs) of detoxification enzymes were screened by RNA-seq, in which 10 up-regulated genes (3 UGTs, 2 GSTs, 5 P450s) may involve the positive temperature effect of TET, and their expression patterns were consistent with qPCR results. Furthermore, the enzyme activities of GSTs and UGTs significantly increased after TET was treated at 15 °C. Especially, the temperature coefficient (TC) of TET was significantly reduced mixed with UGTs enzyme inhibitor 5-NI. Overall, TET showed higher insecticidal activity with increasing temperature, in which detoxifying enzymes associated with regulation of the positive temperature effect of TET on P. xylostella, such as UGTs, GSTs and P450s, are strongly involved. The transcriptome data provide in-depth information to understand the TET mechanism against diamondback moth. Most importantly, we identified detoxification enzymes that might be involved in regulating TET's positive temperature effect process, and contributed to efficient pest management.

Effects of Graphene Oxide Nanosheets in Freshwater Biofilms.

Graphene oxide (GO) properties make it a promising material for graphene-based applications in areas such as biomedicine, agriculture, and the environment. Thus, its production is expected to increase, reaching hundreds of tons every year. One GO final destination is freshwater bodies, possibly affecting the communities of these systems. To clarify the effect that GO may impose in freshwater communities, a fluvial biofilm scraped from submerged river stones was exposed to a range (0.1 to 20 mg/L) of GO concentrations during 96 h. With this approach, we hypothesized that GO can: (1) cause mechanical damage and morphological changes in cell biofilms; (2) interfere with the absorption of light by biofilms; (3) and generate oxidative stress, causing oxidative damage and inducing biochemical and physiological alterations. Our results showed that GO did not inflict mechanical damage. Instead, a positive effect is proposed, linked to the ability of GO to bind cations and increase the micronutrient availability to biofilms. High concentrations of GO increased photosynthetic pigment (chlorophyll a, b, and c, and carotenoids) content as a strategy to capture the available light more effectively as a response to the shading effect. A significant increase in the enzymatic (SOD and GSTs activity) and low molecular weight (lipids and carotenoids) antioxidant response was observed, that efficiently reduced oxidative stress effects, reducing the level of peroxidation, and preserving membrane integrity. Being complex entities, biofilms are more similar to environmental communities and may provide more accurate information to evaluate the impact of GO in aquatic systems.

Multiple resistance of Echinochloa phyllopogon to synthetic auxin, ALS-, and ACCase-inhibiting herbicides in Northeast China

Echinochloa phyllopogon is a self-pollinating allotetraploid weed and a serious threat to global rice production. One sensitive and three multiple-resistant populations collected from two provinces of Northeast China were used to analyze the mechanism of multiple resistance of E. phyllopogon to penoxsulam, metamifop, and quinclorac. Compared with the sensitive population LN12, LN1 showed higher resistance to these three herbicides; LN24 showed medium resistance to penoxsulam and metamifop and higher resistance to quinclorac (274-fold); HLJ4 showed low resistance to penoxsulam and high resistance to metamifop and quinclorac. Target sequence analysis showed no mutations in acetolactate synthase or acetyl-CoA carboxylase genes. In-vitro enzyme activity analysis showed that the activity of the target enzyme of multiple herbicide-resistant populations was similar to that of the sensitive population. The P450 inhibitor, malathion, noticeably increased the sensitivity of LN1, LN24, and HLJ4 to penoxsulam, LN1 to metamifop, and HLJ4 to quinclorac. Under all four treatments, the GSTs activities of resistant and sensitive populations showed an increasing trend from day 1 to day 5, but the sensitivity and activity of GSTs were higher in the multiple-resistant population than that in the sensitive population LN12. This study identified the development of multiple-resistant E. phyllopogon populations that pose a serious threat to rice production in rice fields in Northeast China, preliminarily confirming that multiple-resistance was likely due to non-target-site resistance mechanisms. These populations of E. phyllopogon are likely to be more difficult to control.

PROTECTIVE EFFECT OF SELENIUM ON DIABETIC NEPHROPATHY IN WISTAR RATS

The objective of the present paper is to study and evaluate the effect of selenium supplementation on diabetic nephropathy caused by reactive species generated following hyperglycemia. This study conducted on thirty-five male albino Wistar rats divided into five groups : the first group serves as control (C), the second group was treated by intraperitoneal injection of selenium (sodium selenite ) at 1.89 mg/kg / day, regarding the 3rd groups diabetes was induced by intraperitoneal injection of 150 mg/kg of alloxan (single dose) (DM). One of the diabetic groups was treated by intraperitoneal injection of insulin, 3 IU/100 g PC twice a day (DTins). Another diabetic group is treated with 1.89 mg/kg/day of sodium selenite intraperitoneally (DTSe), and this for 21 days (the two groups treated with selenium were previously treated by gavage of 2 mg/kg/day for 10 days by the same trace element). The results showed in untreated diabetic rats, a drop in body weight, and an increase in blood glucose (13.87mmol/L ± 0.62), urea (10.58 mmol/l ± 0.59), creatinine (64 µmol/l ± 1.3), and phosphorus (1.8 mmol/l ± 0.2). A decrease in serum calcium (1.9 mmol/l±0.1), total protein (58g/l ± 5), albumin (32 g/l ± 3), insulin (0.64 µ UI/ml ± 0.06) and enzymatic activity of serum G6PDH (109.8 m UI/10GR ± 3). With a decrease in anti-oxidant defense, which results in a reduced renal tissue content in GSH (55 nmol/mg of proteins ± 2.2) and of GPx (0.198 µmol/mg of P ± 0.007) and catalase (14.64 µmol H2O2/mn/mg of P ± 0.8) activities. Meanwhile an increase activity of GSTs (0.791 nmol/mn/mg of P ± 0.03) and the concentration of TBARS (0.382 nmol/mg of P ± 0.02) were observed. Sodium selenite induced the antioxidant defense of renal tissue, which protected it from the free radical damage that can be caused by the injection of Alloxan.

Evaluation of tolerance to λ-cyhalothrin and response of detoxification enzymes in silkworms reared on artificial diet

A representative silkworm rearing mode of Ⅰ-Ⅲ instars reared on artificial diet and Ⅳ-Ⅴ instars reared on fresh mulberry leaves has been recognized in some sericultural areas of China. Under this rearing mode, silkworms are prone to be poisoned by pesticide residues on mulberry leaves at the Ⅳ and Ⅴ instar stages. As one of the most widely applied insecticides, λ-cyhalothrin was used to study the insecticide tolerance of silkworm reared on artificial diet (referred as the AD group). Our results showed that the newly ecdysized Ⅳ instar larvae in the AD group were less tolerant to λ-cyhalothrin compared to the mulberry leaves reared group (referred as the ML group). After continuous exposure to trace λ-cyhalothrin, the weight gain and the survival rate of silkworms were significantly lower in the AD group than those in the ML group, even though compensatory growth was observed in the control of the AD group. Histopathology and ultrastructure of fat body showed that λ-cyhalothrin induced more severe cell injuries in the AD group, such as shrunken nucleus, dilatation of endoplasmic reticulum, and mitochondrial swelling. The transcription levels of detoxification related genes (CYP4M5, CYP6AB4, CarE2, CarE5, GSTe1 and GSTe3) and the enzyme activities of P450s, CarEs and GSTs were inducible by trace λ-cyhalothrin in a time-specific manner, and the data showed that the response of P450 enzyme activity was retarded in the AD group, indicating a potential reason for a higher sensitivity to λ-cyhalothrin. Our results provided a new clue for the study of the relationship between feed nutrition and detoxification ability, and also provided an important reference for the development of modern silkworm rearing mode.

Dangerous connections: biochemical and behavioral traits in Daphnia magna and Daphnia longispina exposed to ecologically relevant amounts of paracetamol.

Exposure of nontarget organisms to therapeutic agents can cause distinct toxic effects, even at low concentrations. Paracetamol is a painkiller drug, widely used in human and veterinary therapies, being frequently found in the aquatic compartment in considerable amounts. Its toxicity has already been established for some species, but its full ecotoxicological potential is still not sufficiently described. To characterize the ecotoxicity of paracetamol, the present study evaluated several parameters, such as acute immobilization (EC50 calculation), biochemical alterations, and behavioral effects, in two species of freshwater microcrustaceans of the genus Daphnia (D. magna and D. longispina). To increase the relevance of the data obtained, animals were exposed to levels of paracetamol similar to those already reported to occur in the wild. Data showed antioxidant responses in both species, namely an increase of catalase and GSTs activities in D. magna. On the contrary, effects of paracetamol on D. longispina included only an impairment of GSTs activity. Despite the absence of anticholinesterasic effects, behavioral modifications were also observed. This set of data indicates that realistic levels of paracetamol may trigger the activation of the antioxidant defense system of freshwater crustaceans, causing changes in behavioral traits (increase in swimming time, but with a reduction in swimming distance) of unknown etiology that are likely to affect normal life traits of wild populations.

Twists and turns of an oyster's life: effects of different depuration periods on physiological biochemical functions of oysters.

Aquaculture activities are often established in the vicinity of highly populated, potentially contaminated areas. Animals cultured at such locations, namely bivalves, are frequently used as test organisms in ecotoxicological testing. In this case, a period of depuration is required to allow the normalization of physiological processes, which are likely to be altered after exposure to a multiplicity of waterborne contaminants occurring in the wild. One of the most important species in modern marine aquaculture is the oyster species Crassostrea gigas. The aim of this study was to assess if the current depuration time frame of 24 h (adopted by most aquaculture facilities), is long enough to permit oysters to revert potential toxic effects exerted by environmental contaminants, allowing their use in laboratory-based ecotoxicological studies. The selected approach involved the monitoring of biochemical (antioxidant defence, oxidative damage, phase II metabolism, and neurological homeostasis) and physiological (condition index) parameters, along a period of 42 days. The obtained results showed that a period of 24 h does not revert any of the potential toxic effects caused by environmental contaminants to which animals may have been previously subjected; even a period of 42 days was not long enough for the oysters to completely normalize the levels of their antioxidant defences, namely total GPx activity, which increased over time. Lipid peroxidation was also increased during the depuration period, and the activity of the metabolic isoenzymes GSTs was significantly decreased. Furthermore, AChE activity measured in the adductor muscle of oysters was increased over time. These assumptions suggest that a period of depuration longer than 24 h is mandatory to obtain adequate test organisms of this oyster species, to be used for ecotoxicological testing purposes.

Physiological Analysis and Transcriptome Analysis of Asian Honey Bee (Apis cerana cerana) in Response to Sublethal Neonicotinoid Imidacloprid.

Simple SummaryIn recent decades, there has been serious concern about the decline of honeybees in the world. One of the most debated factors contributing to bee population declines is exposure to pesticides, especially neonicotinoids. The most important Chinese indigenous species, Apis cerana presents a high risk on exposure to neonicotinoids, but few studies have explored the sublethal effects of neonicotinoids on Apis cerana. In this study, we highlight the molecular mechanism underlying the A. cerana toxicological characteristic against imidacloprid, the most commonly detected neonicotinoid in honey samples from Apis cerana. We not only investigated the physiological effects from sublethal doses of imidacloprid, but also identified several genes involved in a general stress response, including metabolism, catalytic activity, and structural molecule activity, response to stimulus, transporter activity, and signal transducer activity, as indicated by the GO analysis. In addition, genes related to the phenylalanine metabolism pathway, FoxO signaling pathway, and mTOR signaling pathway as indicated in the KEGG analysis were significantly up-related in the exposed bees. Overall, this study reveals the short-term sublethal effects of imidacloprid, which may be useful for accurately assessing the toxicity risk of Asian honeybees.Asian honey bee (Apis cerana) is the most important Chinese indigenous species, while its toxicological characteristic against neonicotinoids is poorly known. Here, we combined physiological experiments with a genome-wide transcriptome analysis to understand the molecular basis of genetic variation that responds to sublethal imidacloprid at different exposure durations in A. cerana. We found that LC5 dose of imidacloprid had a negative impact on climbing ability and sucrose responsiveness in A. cerana. When bees were fed with LC5 dose of imidacloprid, the enzyme activities of P450 and CarE were decreased, while the GSTs activity was not influenced by the pesticide exposure. The dynamic transcriptomic profiles of A. cerana workers exposed to LC5 dose of imidacloprid for 1 h, 8 h, and 16 h were obtained by high-throughput RNA-sequencing. We performed the expression patterns of differentially expressed genes (DEGs) through trend analysis, and conducted the gene ontology analysis and KEGG pathway enrichment analysis with DEGs in up- and down-regulated pattern profiles. We observed that more genes involved in metabolism, catalytic activity, and structural molecule activity are down-regulated; while more up-regulated genes were enriched in terms associated with response to stimulus, transporter activity, and signal transducer activity. Additionally, genes related to the phenylalanine metabolism pathway, FoxO signaling pathway, and mTOR signaling pathway as indicated in the KEGG analysis were significantly up-related in the exposed bees. Our findings provide a comprehensive understanding of Asian honey bee in response to neonicotinoids sublethal toxicity, and could be used to further investigate the complex molecular mechanisms in Asian honey bee under pesticide stress.

Susceptibility of Dermanyssus gallinae from China to acaricides and functional analysis of glutathione S-transferases associated with beta-cypermethrin resistance

Dermanyssus gallinae poses a significant threat to poultry production, and the resistance to pyrethroids has been identified worldwide. Periodic monitoring of acaricide resistance in D. gallinae is very important for its control, and molecular mechanism associated with beta-cypermethrin resistance in D. gallinae is not fully clear. Results showed, four field isolates of CBP-1, CBP-2, CBP-5 and CBY-1 from China remained either susceptible or with decreased susceptibility (resistance ratio < 5.0) to phoxim, amitraz, propoxur and carbaryl. Four field isolates of CBP-1, CBP-3, CBY-2 and CBH-1 had developed high or extremely high level of resistance (resistance ratio ≥ 40.0) to beta-cypermethrin or permethrin. Detoxification enzyme activity of GSTs was significantly higher in beta-cypermethrin resistant (RS) than susceptible strain (SS), indicating that GSTs are probably involved in beta-cypermethrin resistance in D. gallinae. The recombinant GSTs (rGST-1, 2, 3) showed a pronounced activity toward the conjugates of 1-chloro-2, 4 dinitrobenzene (CDNB) and glutathione (GSH), with rGST-1 presenting the highest enzymatic activity. Constitutive over-expression of Deg-GST-2 was detected in RS strain, and GSTs genes were all inducible with the treatment of beta-cypermethrin in SS and RS strains. More importantly, knocking down Deg-GST-2 gene expression by RNAi increased the susceptibility of RS strain to beta-cypermethrin. HPLC analysis indicated that rGST-1 protein could metabolize phoxim directly, but rGSTs could not directly metabolize beta-cypermethrin. Our results indicated that some field isolates of D. gallinae from China had developed high level of resistance to pyrethroids, and elevated GSTs activity as well as increased GSTs expression levels were involved in beta-cypermethrin resistance, but the three evaluated GSTs did not play a direct role in the metabolism of beta-cypermethrin.

Metabolic resistance mechanism in Aedes aegypti from Lagos State, Nigeria

BackgroundAedes aegypti transmits several arboviral diseases of global public health threat such as dengue, zika, and yellow fever. Recently, a series of yellow fever outbreaks have been reported in different parts of the country. Globally, the control of mosquito-borne diseases has relied heavily on insecticides based vector control efforts. Therefore, we assessed the susceptibility status to three different classes of WHO approved insecticides and evaluated the importance of detoxifying enzymes on insecticides resistance in Aedes aegypti collected from Lagos State, Nigeria. Aedes aegypti immature stages were collected from suitable habitats in peri-domestic areas of Alimosho, Kosofe, Badagry, and Ibeju-Lekki Local Government Areas (LGAs) of Lagos State, 2–5 days old glucose-fed adult female mosquitoes were exposed to discriminating doses of DDT, permethrin, bendiocarb, and PBO synergist using WHO standard procedure and kits. Identification was through morphological means only.ResultsResistance to DDT and permethrin was recorded in all the LGAs, suspected resistance to bendiocarb was recorded in Aedes aegypti from Alimosho while full susceptibility was recorded in other LGAs. PBO synergist significantly increases the 24 h mortality of DDT and permethrin-resistant Aedes aegypti in all the LGAs. The activities of both GSTs and cytochrome P450s increase with decreasing mortality for Aedes aegypti, regression value (R2) ranges from 0.8889 to 0.6224 for GSTs and 0.4379 to 0.616 for cytochrome P450s.ConclusionsAedes aegypti population from Lagos State, Nigeria, have developed resistance to DDT and permethrin, the activities of P450s and GST were implicated in DDT and permethrin resistance in this study. Therefore, a need for regular insecticides monitoring and PBO should be incorporated into Aedes aegypti insecticides control strategies to forestall development of resistance to DDT and pyrethriods.

Standard and biochemical toxicological effects of zinc pyrithione in Daphnia magna and Daphnia longispina

Chemical toxicity in the environment may be the consequence of exposure of living organisms to multiple substances, with distinct putative effects. Among this mulytiplicity of chemicals that occur in the wild, pharmaceutical drugs and antifoulers are prone to exert toxic effects on non-target organisms. To characterize the toxicity elicited by a compound of this specific class, the present study used standard and biochemical-based tools to quantify the toxic response of the antifouler and antidandruff zinc pyrithione in Daphnia magna and Daphnia longispina. The analised parameters were immobility, reproduction, behavioral alteration (swimming patterns), anti-oxidant defense (catalase activity), metabolism (GSTs activities), and neurotoxicity (ChE activity) after exposure to sublethal concentrations of this drug. Exposure to zinc pyrithione has been shown to have neurotoxic and oxidative effects, with changes in swimming behavior. There were no changes in reproductive traits of exposed individuals, from both species. The obtained data demonstrate that ecologically relevant levels of zinc pyrithione can deleteriously alter critical parameters in two distinct freshwater microcrustacean species, although with distinct toxicity patterns and outcomes.

Effects of pH on salicylic acid toxicity in terms of biomarkers determined in the marine gastropod Gibbula umbilicalis

Alterations of the physical-chemical properties of the oceans due to anthropogenic activities are, at present, one of the most concerning environmental issues studied by researchers. One of these issues is ocean acidification, mainly caused by overproduction and release of carbon dioxide (CO2) from anthropogenic sources. Another component of environmental degradation is related to the production and release of potential toxic compounds, namely active pharmaceutical ingredients, into the aquatic environment that, combined with oceanic acidification, can cause unpredictable and never before considered deleterious effects on non-target marine organisms. Regarding this issue, the hereby study used predictions of future ocean acidification to simulate realistic scenarios of environmental exposure to a common therapeutic drug, salicylic acid (SA), in the marine gastropod Gibbula umbilicalis under different pH values. This species was exposed to a range of pH values (8.2, 7.9 and 7.6), and to already reported environmentally realistic concentrations (5, 25 and 125 μg/L) of SA. To evaluate the effects of these environmental stressors, key physiological biomarkers (GSTs, CAT, TBARS, AChE and COX) and shell hardness (SH) were quantified. Results from the present study showed that CAT and GSTs activities were enhanced by SA under water acidification; increased lipid peroxidation was also observed in organisms exposed to SA in more acidic media. In addition, the hereby study demonstrated the neurotoxic effects of SA through the inhibition of AChE. Effects were also observed in terms of COX activity, showing that SA absorption may be affected by water acidification. In terms of SH, the obtained data suggest that SA may alter the physical integrity of shells of exposed organisms. It is possible to conclude that the combination of seawater acidification and exposure to toxic xenobiotics (namely to the drug SA) may be strenuous to marine communities, making aquatic biota more susceptible to xenobiotics, and consequently endangering marine life in an unpredictable extent.

Toxic effects of environmentally realistic concentrations of diclofenac in organisms from two distinct trophic levels, Hediste diversicolor and Solea senegalensis

The use of pharmaceutical drugs has systematically increased, resulting in their environmental presence and exertion of effects on non-target aquatic organisms. Diclofenac (DCF) is an analgesic, anti-inflammatory and antipyretic drug, frequently found in the aquatic compartment. The present work analyzed the ecotoxicological effects of DCF in the marine polychaete Hediste diversicolor and in the marine fish Solea senegalensis. In addition, the putative toxic effects of DCF along a simulated food chain were studied, by feeding individuals of S. senegalensis with H. diversicolor previously exposed to DCF. Biomarkers of anti-oxidant defense (catalase, CAT), phase II metabolism (glutathione S-transferases, GSTs) and neurotoxicity (acetylcholinesterase, AChE) were quantified. The obtained results demonstrated that DCF did not affect CAT activity in organisms of both species directly exposed through the water, suggesting the absence of oxidative effects. In addition, organisms directly or indirectly exposed to DCF showed an increase of GSTs activities, suggesting an additional challenge to the metabolism of the exposed individuals. However, significant decreases in the activities of CAT and AChE were observed in fish fed with worms previously exposed to DCF. These data suggest that direct or indirect exposure to DCF may cause significant physiological modifications in aquatic organisms. In addition, exposure of wild organisms via contaminated food may lead to toxicological effects which may differ from alterations elicited by direct exposure. Such toxicological differences, between direct (waterborne) and trophic (via contaminated feed) exposures were qualitatively distinct, and need to be fully addressed when considering the consequences of environmental contamination by therapeutic drugs.

First Report of Biochemical Mechanisms of Insecticide Resistance in the Field Population of Culex pipiens (Diptera: Culicidae) From Sari, Mazandaran, North of Iran

Culex pipiens play an important role in transmission of infectious diseases. Vector control by chemical pesticides, leads inevitably to resistance development. Understanding the underlying resistance mechanisms can help improve the control programmes and insecticide resistance management. The total contents of cytochrome p450s and the activities of glutathione S-transferases, alpha- and beta-esterases and inhibition rates of acetylcholine esterase (by propoxur) were measured in the field population of Cx. pipiens collected from Sari County, North of Iran, in 2016 and the results were compared with those of the laboratory susceptible strain according to the biochemical assay methods of WHO for adult mosquitoes. Independent sample t-test was used to compare the mean values of enzyme activities/contents between filed and laboratory susceptible populations. The enzyme ratio of cytochrome p450s, alpha- and beta-esterases in the field population was 2.07, 3.72 and 1.36 respectively when compared with the results of the laboratory population. Although not statistically significant, the mean GSTs activities in the field population was marginally less than the laboratory population (ER=0.92). Acetylcholinesterase was insensitive to propoxur in 62.82% of the individuals of the tested field population. There was a significant difference (P< 0.05) between all values of the activities/contents of the enzyme in the field population except for GSTs compared with the laboratory susceptible strain. The highest enzyme activity was related to alpha esterase. The present study showed a range of metabolic mechanisms, comprising p450s and esterases combined with target site insensitivity of AChE, contributing to organophosphate, carbamate and pyrethroid resistance in the field population of Cx. pipiens.

Multi-parametric analysis of ciprofloxacin toxicity at ecologically relevant levels: Short- and long-term effects on Daphnia magna

The increased presence of emergent compounds, such as pharmaceuticals drugs, in the aquatic compartment has been acknowledged as an evolving environmental issue whose consequences are not yet fully characterized. Specific classes of pharmaceutical drugs, such as fluoroquinolone antibiotics, can exert toxic effects to non-target species with ecological significance, since these compounds are environmentally stable and persistent, and may interact with some of the key physiologic processes of organisms. Despite such characteristics, knowledge about the effects of these drugs is still scarce, especially to non-target organisms. The present study aimed to evaluate the effects of chronic and acute exposures of the cladoceran Daphnia magna to the fluoroquinolone antibiotic ciprofloxacin. Putative toxic effects were assessed, following acute and chronic exposures to ecologically relevant concentrations of ciprofloxacin, through enzymatic (cholinesterase – ChEs, catalase – CAT, glutathione S-transferases – GSTs) and non-enzymatic (thiobarbituric acid reactive substances – TBARS, glycogen – Gly) biomarkers. In addition, we also determined behavioural (swimming distance – SD) and morphological (body length of the first brood – BL1B) endpoints in animals exposed to this drug. Ciprofloxacin acute exposure resulted in increased CAT and ChEs activities, and inhibited GSTs activity. After chronic exposure, ChEs activity was significantly inhibited, while GSTs activity was significantly enhanced. TBARS levels were only increased at higher concentrations of ciprofloxacin. CAT activity and Gly content did not evidence a clear and significant pattern of variation. SD was slightly inhibited during dark cycles. BL1B presented a significant decrease for animals subjected to an intermediate concentration. Results showed that even ecologically relevant concentrations of ciprofloxacin may cause oxidative stress in individuals of D. magna. The present study showed important data that corroborate the occurrence of significant biochemical alterations in key features of an aquatic organism when exposed to relevant levels of a widely used antibiotic, establishing essential links between environmental exposure to this specific drug and putative toxic challenges that may result in irreversible changes and damages, especially at the individual level. However, changes in the size of neonates suggest that population alterations are likely to occur under real scenarios of chronic contamination by this drug.

Biomarker-based assessment of the toxicity of the antifungal clotrimazol to the microcrustacean Daphnia magna

Among the vast list of xenobiotics that may promote harmful effects in aquatic ecosystems, pharmaceuticals are currently a prominent class due to their ability to persist in these environments and also due to the lack of information regarding their effects on the different components of the aquatic biota. Antifungals in particular, despite their massive use, are not extensively studied in environbmental terms. The main objective of this study was to characterize the toxicity of the antifungal clotrimazole to the aquatic organism Daphnia magna. To attain this purpose, the effects of this compound were measured, focusing on the determination of acute lethality, and quantification of biomarkers, such as neurotoxicity (soluble cholinesterases, ChEs); and oxidative stress and metabolism (such as catalase, CAT; and glutathione-S-transferases, GSTs). The toxicity assessment with biomarkers was based on animals exposed to concentrations similar to those already found in surface waters in order to increase the ecological relevance of the obtained data. The results showed that exposure to clotrimazole was able to induce significant increases in both CAT amd GSTs activities. ChE activity was not significantly altered after clotrimazol exposure. In view of the above, it is concluded that the drug studied caused adverse effects in terms of oxidative stress, at an ecological relevant levels, showing that the presence of clotrimazol in the wild is not innocuous.

Dose-Related Modulatory Effects of Polymeric Black Tea Polyphenols (PBPs) on Initiation and Promotion Events in B(a)P and NNK-Induced Lung Carcinogenesis

Our understanding of dose-related effects of polymeric black tea polyphenols (PBPs), the most abundant polyphenols in black tea, is limited. In the present study, the effect of various doses of black tea (0.75, 1.5, and 3%)-derived PBP-rich extract on biochemical parameters and lung carcinogenicity in A/J mice was investigated. Pretreatment with PBPs showed the dose-related decrease in B(a)P-induced expression and activity of CYP1A1 in the liver while CYP1A2 expression and activity in the lung. Dose-dependent significant increase in PBP-mediated over-expression and activity of GSTs (alpha in the liver while pi in the lung) were observed in polyphenol-treated groups. Significant dose-related decrease in number and intensity of BPDE-DNA adducts were observed in liver and lung. Black tea (1.5%, 3%)-derived PBPs showed dose-mediated decrease in lung tumor incidence and multiplicity which was further correlated with different molecular markers like cell proliferation and apoptosis in B(a)P and NNK model. In conclusion, dose-dependent chemopreventive effects of PBPs, both anti-initiating (induction of phase II and inhibition of carcinogen-induced phase-I enzymes leading to decrease in BPDE-DNA adducts) and anti-promoting (decreased cell proliferation and increased apoptosis lowering incidence and/or multiplicity of lung lesions), were observed in A/J mice without significant toxicity.

Plant Glutathione Transferases and Light.

The activity and expression of glutathione transferases (GSTs) depend on several less-known endogenous and well-described exogenous factors, such as the developmental stage, presence, and intensity of different stressors, as well as on the absence or presence and quality of light, which to date have received less attention. In this review, we focus on discussing the role of circadian rhythm, light quality, and intensity in the regulation of plant GSTs. Recent studies demonstrate that diurnal regulation can be recognized in GST activity and gene expression in several plant species. In addition, the content of one of their co-substrates, reduced glutathione (GSH), also shows diurnal changes. Darkness, low light or shade mostly reduces GST activity, while high or excess light significantly elevates both the activity and expression of GSTs and GSH levels. Besides the light-regulated induction and dark inactivation of GSTs, these enzymes can also participate in the signal transduction of visible and UV light. For example, red light may alleviate the harmful effects of pathogens and abiotic stressors by increasing GST activity and expression, as well as GSH content in leaves of different plant species. Based on this knowledge, further research on plants (crops and weeds) or organs and temporal regulation of GST activity and gene expression is necessary for understanding the complex regulation of plant GSTs under various light conditions in order to increase the yield and stress tolerance of plants in the changing environment.