Oxidative parameters of Rhamdia quelen in response to commercial herbicide containing clomazone and recovery pattern

In this study, fish Rhamdia quelen, were exposed to different concentrations of herbicide clomazone: 0.0 (control), 0.45 and 0.91 mg L⁻¹. After exposure for 8 days to herbicide, fish were transferred to clean water for a recovery period (8 days). Oxidative stress indicators such as thiobarbituric acid reactive substances (TBARS) levels and protein carbonyl content, as well as antioxidant defenses, such as catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), ascorbic acid and non-protein thiols levels were studied, using the liver, brain and muscle tissues. Herbicide exposure increased TBARS in muscle and in liver at higher concentration. In liver protein carbonylation increased and catalase activity did not change in fish exposed to herbicide. SOD enhanced in liver at concentration of 0.91 mg L⁻¹. GST, ascorbic acid and non-protein thiols levels increase at both concentrations. At the end of the recovery period the most of the parameters recovered whereas GST and ascorbic acid remain elevated. The present study demonstrates the occurrence of disorders in antioxidant parameters and importance in the assessment of the potential risk of herbicides as clomazone on fish species.     

Toxic effects of novel organophosphorus insecticide (RPR-V) on certain biochemical parameters of euryhaline fish, Oreochromis mossambicus

The euryhaline fish, Oreochromis mossambicus was exposed to sub-lethal concentration (0.017 mg L⁻¹) of a novel phosphorothionate, 2-butenoic acid-3-(diethoxy phosphinothionyl) ethyl ester (RPR-V) for 30 days and allowed to recover for 7 days. Important biomarker enzymes were assayed in plasma, brain, gill, liver, kidney, and muscle during exposure tenures of day-3, -7, -15, -30, and also at 7 days (withdrawal) after stopping treatment. Acetylcholinesterase (AChE) activities of brain, gill, and muscle were strongly inhibited by 67, 75, and 66%, respectively, on day-30. Exposure (time) dependent increases in alanine aminotransferase (ALAT), and aspartate aminotransferase (ASAT), acid phosphatase (AcP), and alkaline phosphatase (AkP), activities in plasma and kidney; AcP and AkP activities in gill were noticed. However, significant decrease in ALAT, ASAT, AcP, and AkP activities in liver was observed. The depletion of glycogen was observed in liver, brain, and gill tissues, an indication of typical stress related response of the fish with pesticide. A significant increase in lactate dehydrogenase (LDH) activity in gill and brain was observed and decreased in liver and muscle, indicating tissue damage and muscular harm. Depletion of glutathione (GSH) was observed in the above tissues, there by enhancing the lipid peroxidation resulting in cell damage. The induction in hepatic glutathione-S-transferase (GST) levels indicates the protection against the toxicity of xenobiotic-induced lipid peroxidation. There was a significant recovery in all the above biochemical parameters, in all the tissues of fish after a recovery period of 7 days. These results revealed that RPR-V affects the intermediary metabolism of O. mossambicus and the increase of biomarker enzymes in plasma, might be due to the necrosis of liver.     

In vivo chlorpyrifos induced oxidative stress: Attenuation by antioxidant vitamins

Chlorpyrifos (O,O′-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothionate, CPF) exposure in rats causes elevation in the levels of thiobarbituric acid reactive substances (TBARS) and inhibition of acetylcholinesterase (AChE), superoxide dismutase (SOD), catalase (CAT), and glucose-6-phosphate dehydrogenase (G6PDH) activities in the liver, kidney, spleen, and brain of rats. The sublethal exposure of CPF also causes decrease in the levels of reduced glutathione (GSH) and consequent increase in oxidized glutathione (GSSG) levels, resulting in a significant decrease in GSH/GSSG ratio in all the rat tissues tested. These results clearly indicate that CPF exposure causes oxidative stress in rat tissues. However, CPF exposure to rats fed with antioxidant vitamins (vitamin A, E, and C) for 1 month, prevented derangement of these antioxidant parameters. The accumulation of TBARS was also not seen in tissues of rats fed with antioxidant vitamins on CPF exposure. AChE activity, which is sensitive to OP pesticides, was also not significantly inhibited in these rats on CPF exposure. The present findings clearly show that oral intake of a mixture of vitamin A, E, and C, protects the rats from CPF induced oxidative stress and suggesting that this treatment alleviates the toxicity of this pesticide.     

λ-cyhalothrin and cypermethrin induced in vivo alterations in the activity of acetylcholinesterase in a freshwater fish, Channa punctatus (Bloch)

In the present study, the in vivo effects of λ-cyhalothrin and cypermethrin on the activity of acetylcholinesterase (AChE, EC 3.1.1.7) were evaluated for 96 h in brain, muscle and gills of Channa punctatus. Both compounds exhibited tissue specific as well as dose dependent decrease in the activity of AChE. The treated fish showed a significant decrease in the activity of AChE in brain and a lesser inhibition in muscle and gills in response to the increasing concentrations of λ-cyhalothrin as well as cypermethrin. Our results indicated that the brain was the main target organ for both insecticides, followed by muscle and gills, as determined by AChE inhibition study. However, these organs showed variations in the degree of AChE inhibition for separate treatments of both insecticides. The λ-cyhalothrin was a more potent AChE inhibitor as compared to cypermethrin. These findings indicated that apart from the established mechanism of delayed closure of sodium ion channels, these pyrethroids inhibit the activity of AChE in C. punctatus which could further aggravate their neurotoxic effects.     

Catalase activity as a potential vital biomarker of fish intoxication by the herbicide aminotriazole

The objective of this study was to investigate the effects of the herbicide 3-amino-1,2,4-triazole (AMT) on the activities of catalase and lactate dehydrogenase (LDH) in blood (plasma and erythrocytes) and eight solid tissues of goldfish, Carassius auratus. Injection of goldfish with AMT (0.5 mg/gww AMT in 0.9% NaCl) resulted in a significant decrease in catalase activity 24 h post-injection in most tissues investigated. In white and red muscle, kidney, heart, liver, brain and erythrocytes the activity of catalase decreased by 61%, 69%, 64%, 48%, 40%, 27% and 26%, respectively, in comparison to the values seen in animals injected with physiological saline (0.9% NaCl). However, the activity of LDH decreased only in red muscle (by 19%) after AMT injection, whereas in plasma it increased by 137%. Protein carbonyl levels, a measure of oxidative damage to proteins, did not change in plasma in goldfish injected with AMT and total hemoglobin levels in AMT-injected fish, although lower compared with uninjected controls, did not differ from values in saline-injected controls. It is proposed that catalase activity in erythrocytes and white muscle might be usefully developed as a potential marker for fish intoxication by aminotriazole and other related herbicides.     

Tissue-specific antioxidative and neurotoxic responses to diazinon in Oreochromis niloticus

The purpose of this study was to evaluate oxidative stress and neurotoxic potential of organophosphorus (OP) insecticide diazinon in the sentinel freshwater fish, Oreochromis niloticus. Antioxidant and acetylcholinesterase (AChE) enzyme activities and malondialdehyde (MDA) and protein levels were measured spectrophotometrically in gill, kidney, alimentary tract, and muscle tissues of fish treated with sub-lethal diazinon concentrations for 1, 7, 15, and 30 days. Dose-dependent inhibitions of AChE were observed in all the experimental fish. On the contrary of alimentary tract, MDA levels were elevated in kidney and muscle and gill was not affected. AChE and MDA levels intercorrelated in kidney and muscle tissues. Diazinon had increased superoxide dismutase (SOD) activities in all the tissues, while kidney was the most affected tissue. Tissue-specific alterations were observed on catalase (CAT) and glutathione peroxidase (GPx) activities; however, the activities were not changed in gill and muscle tissues for GPx and in gill, muscle, and kidney tissues for CAT. Protein levels decreased in kidney, muscle, and alimentary tract, while increased in gill and alimentary tract in 15 days. With respect to these results, diazinon has oxidative and neurotoxic potentials in O. niloticus. Observed changes with diazinon treatment were generally tissue-specific and dose-dependent.     

Concentration related responses of chlorpyriphos in antioxidant, anaerobic and protein synthesizing machinery of the freshwater fish, Heteropneustes fossilis

Impacts of chlorpyriphos (2, 4, 6 ppm) on the profiles of antioxidant (catalase) and anaerobic (lactate dehydrogenase) enzymes and other macromolecular contents (DNA, RNA, protein) of various tissues of the freshwater fish, Heteropneustes fossilis were studied. Chlorpyriphos significantly decreased the specific activity of catalase (CAT) and lactate dehydrogenase (LDH) in the brain, liver, gill and skeletal muscle of the fish. The reduction in specific activity might be due to the binding of chlorpyriphos or its metabolites with the enzyme molecules or affecting the synthesis and/or degradation of the enzymes. Like enzymes, the DNA, RNA and protein contents decreased in the brain, liver, gill and skeletal muscle of the fish as a function of increase in chlorpyriphos concentrations (2-6 ppm). The chlorpyriphos-induced reduction in these biochemical constituents might be because of alteration in their turnover (synthesis/degradation) in different tissues. The maximum effects on CAT, LDH, DNA, RNA and protein were obtained in response to 6 ppm chlorpyriphos. The present findings suggest chlorpyriphos concentration related impairment in antioxidative, anaerobic and protein synthesizing capacity of the fish. Therefore, the use of higher concentrations of chlorpyriphos should be avoided to protect the health of economically important freshwater food fish.     

Endocrine disruption and metabolic changes following exposure of Cyprinus carpio to diethyl phthalate

Diethyl phthalate (DEP) enter into aquatic environment from industries manufacturing cosmetics, plastic and many commercial products and can pose potential fish and human health hazard. This experiment evaluated effects of DEP in adult male (89 g) common carp (Cyprinus carpio) by exposing them to fractions of LC₅₀ (1/500-1/2.5) doses with every change of water for 28 days. Vitellogenin induction metabolic enzymes, somatic indices and bioaccumulation were studied on 7th, 14th, 21st and 28th day. The 96th hour LC₅₀ of DEP in fingerlings was found to be 48 mg/L. Compared to control, except increase (P < 0.01) in alkaline phosphatase activity (EC 3.1.3.1) and liver size, there was decrease (P < 0.01) in activity of acid phosphatase (EC 3.1.3.2), aspartate aminotransferase (EC 2.6.1.1), alanine aminotransferase (EC 2.6.1.2) and testiculosomatic index following exposure to 1, 5 and 20 ppm DEP. Significant (P < 0.01) dose dependant vitellogenin induction was observed with exposure of fish to 0.1, 1 and 5 ppm DEP. The bioaccumulation of DEP in testis, liver, brain, gills and more importantly in muscle tissues of fish increased significantly (P < 0.01) with increase of dose from 1 to 5 ppm. Significant interaction (P < 0.01) of dose and duration of exposure indicated that exposure period of a week to two was sufficient to bring about changes in quantifiable parameters studied. Fish exposed to 20 ppm DEP became lethargic and discolored during onset of the 4th week. This is the first report describing metabolic changes and vitellogenin induction following exposure of C. carpio to DEP dose that is as low as 1/500th fraction of LC₅₀.     

Metabolic and histological parameters of silver catfish (Rhamdia quelen) exposed to commercial formulation of 2,4-dichlorophenoxiacetic acid (2,4-D) herbicide

The objective of this study was to investigate the effects of commercial formulation of herbicide 2,4-D on metabolic parameters, acetylcholinesterase (AChE) activity and liver histological evaluation of silver catfish (Rhamdia quelen) exposed for 96 h. AChE activity increased in brain (600 and 700 mg L⁻¹) and decreased in all concentrations tested in muscle tissue. Hepatic glycogen was reduced after 2,4-D exposure ranging from 47.67% (400 mg L⁻¹) until 59.3% (700 mg L⁻¹). Hepatic tissue showed lactate reduction at all 2,4-D concentrations tested and glucose was reduced only at 700 mg L⁻¹. In the highest concentration tested hepatic glycogen and glucose reduced instead plasma glucose levels increased. White muscle tissue showed glycogen reduction in fingerlings exposed to all herbicide concentrations and glucose reduction at 700 mg L⁻¹. Muscle lactate levels increase at all 2,4-D concentrations tested. Vacuolation of hepatocytes and changes in its arrangement cords were observed by histologic analysis in group treated with 700 mg/L of 2,4-D. These results suggest that silver catfish exposed to concentrations of 2,4-D near of CL₅₀ showed metabolic and histological response to compensate some stress caused by herbicide exposure. Taken together parameters measured can be used as biomarkers to monitor herbicide contaminated water.     

Some hematological,biochemical, and enzymological parameters of a fresh-water teleost fish, Channa punctatus, exposed to sublethal concentrations of quinalphos

Alterations in the levels of hemoglobin, total plasma proteins, glucose, and lactic acid in the blood; glycogen and lactic acid content of liver and white skeletal muscle; and the activities of lactate dehydrogenase, pyruvate dehydrogenase, and succinate dehydrogenase in liver, kidney, intestine, brain, gills, and muscles were examined in the fresh-water snake-head fish, Channa punctatus, after exposure to a sublethal concentration (25 μg/liter) of quinalphos for 60 and 120 days. Hemoglobin, plasma protein, glucose, and lactic acid decreased in pesticide-exposed fish. The glycogen content of the liver and muscles increased but lactic acid decreased. Lactate dehydrogenase activity decreased in all six tissues. Pyruvate dehydrogenase activity of liver, kidney, gill, and muscle decreased, but the enzyme activity was elevated in intestine and brain. In intestine, succinate dehydrogenase activity was elevated, and in the remaining five tissues the enzyme activity was significantly reduced. The present study showed that formation of glycogen and its breakdown was impaired in the liver, and aerobic oxidation of nutrients was adversely affected in quinalphos-exposed fish.     

Biochemical and histological hepatic changes of Nile tilapia Oreochromis niloticus exposed to carbaryl

The purpose of this study was to evaluate biochemical and morphological responses induced by carbaryl in the liver of Nile tilapia (Oreochromis niloticus) exposed during 21 days to sublethal concentrations (0.25 and 0.5 mg L⁻¹), testing also recover for 14 days in clean water, after 14 days exposure. The activities of the following enzymes were measured: superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), glutathione reductase (GR), and reduced (GSH) and oxidized glutathione (GSSG). Globally, our data showed that exposure to carbaryl decreased the SOD, CAT, GR, and GST activities, except for the SOD and GST activities after 14 days exposure to 0.25 mg L⁻¹. In contrast, after 14 days exposure the GR activity of the hepatic tissue from carbaryl-treated fish showed significant elevation in relation to the control. When fish were left to recover, a positive response was seen in the GSH and GSSG contents. The results of the recovery group suggest that the toxicity produced by carbaryl is reversible to some extent within 15 days. The liver histological analysis showed differences between fish concerning the cellular vacuolization degree (VD) of the hepatocytes. In fish exposed to carbaryl it was observed an increasing hepatocellular basophilia. No other histological alterations were observed when fish was exposed to carbaryl, except a few necrotic foci at day 7. The sections stained with PAS reaction showed that the vacuolization was always not due to glycogen deposits, thus suggesting lipid accumulation. The combined increased basophilia and glycogen depletion is a common, although non-specific, liver response to many toxicants. In short, this work shows a relation between histological and biochemical changes in liver and carbaryl exposure. The effects of carbaryl were observed at different concentrations.     

Effects of the herbicide LASSO MTX (alachlor 42% W/V) on biometric parameters and liver biomarkers in the common carp (Cyprinus carpio)

The aim of the study was to evaluate the effect of subchronic exposure to the herbicide LASSO MTX (alachlor 42% W/V) on biometric parameters and important liver biomarkers in the common carp (Cyprinus carpio). One year old fish were exposed for 28 days to LASSO MTX added to the tank water at concentrations of 240 and 2400 μg L⁻¹. The exposure did not affect fish biometric parameters. Glutathione-S-tranferase (GST) activity in liver (hepatopancreas) remained unchanged in exposed fish when compared to controls. However, significant induction of total cytochrome P 450 (CYP 450), ethoxyresorufin-O-deethylase (EROD) activity and elevated glutathione (GSH) in liver of exposed fish were detected.     

Effects of trichlorfon and sodium dodecyl sulphate on antioxidant defense system and acetylcholinesterase of Tilapia nilotica in vitro

The effects of organophosphorus insecticide trichlorfon, surfactant sodium dodecyl sulphate (SDS), and the mixture of trichlorfon and SDS on the antioxidant defense system and acetylcholinesterase (AChE) in Tilapia nilotica were assessed in vitro. Various concentrations of trichlorfon (0, 0.0001, 0.001, 0.01, 0.1 and 1 g/L) and SDS (0, 0.0625, 0.125, 0.25, 0.5, 1 g/L) were incubated with homogenate of liver and muscle, respectively, at 25 °C for 0, 30, 60 and 90 min. Two concentrations of mixture of trichlorfon and SDS (0.0001 g/L trichlorfon + 0.5 g/L SDS, 0.1 g/L trichlorfon + 0.5 g/L SDS) and 0.0001 g/L trichlorfon, 0.1 g/L trichlorfon, 0.5 g/L SDS and control, were incubated simultaneously with homogenate of liver and muscle, respectively, at 25 °C for 60 min. After incubation, the content of reduced-glutathione (GSH) and the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) in homogenate of liver were determined, and the activities of AChE in homogenate of muscle were also measured.Treatment with trichlorfon caused a significant concentration-dependent and time-related inhibition of AChE activity at all treatment concentrations and times since trichlorfon is a cholinesterase inhibitor. For the same trichlorfon treatment, an apparent decrease in GSH content was found in concentration of 0.01, 0.1, 1 g/L, whereas no significant alteration in antioxidant enzyme activity were found at all experiment concentrations and times, which might indicate that antioxidant enzymes have not involved in the metabolism of trichlorfon. The depletion of GSH might indicate that ROS could be involved in the toxic effects of trichlorfon. Exposure of SDS can inhibit activities of AChE, GST and CAT at concentrations of 0.5 and/or 1 g/L, which could be due to the denaturing process of SDS to the enzymes. For the mixture exposure of trichlorfon and SDS, the effect of the mixture of 0.0001 g/L trichlorfon and 0.5 g/L SDS on inhibition of AChE shows synergistic other than simple additive of trichlorfon and SDS. The combined effects of chemicals and detergents deserve to be particularly noted. It should be noted that the toxicity experiments were made in tissue homogenates instead of whole organisms. The responses against the toxic compounds will not be the same in both systems.     

Evaluation of etoxazole toxicity in the liver of Oreochromis niloticus

The effects of etoxazole were evaluated in freshwater fish Oreochromis niloticus from five different sublethal etoxazole concentrations in order to study the biochemical response, photometrically. No changes were observed in the activities of antioxidant enzymes such as superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), and glutathione peroxidase (GPx, EC 1.11.1.9). These were measured in liver after 1, 7, and 15 days of exposure to sublethal concentrations of 0.2, 0.4, 0.6, 0.8, and 1% of field application rate (134.75 ppm). This study also investigated the levels of neurotoxic effects by the determination of acetylcholine esterase (AChE EC 3.1.1.7) and sodium-potassium adenosine 5^′-triphosphatase (Na⁺K⁺-ATPase, EC 3.6.3.9) activities. The exposure of fish led to sharp depletion in AChE activity while there is no significant alteration in Na⁺K⁺-ATPase activity. Up to 80% decreases were observed in the AChE activity. Since no difference was found in the activity of glutamate-pyruvate transaminase (GPT, EC 2.6.1.2), etoxazole did not show hepatotoxic effect. The results of the present study show that increase in the malondialdehyde (MDA) contents and decrease in the AChE activity can be used as biomarkers for monitoring toxicity in etoxazole exposure.     

Protective effects of Nigella sativa oil on propoxur-induced toxicity and oxidative stress in rat brain regions

Propoxur (PPr) is a widely used broad spectrum carbamate insecticide mainly used to control household pests. Because of the widespread use of pesticides for domestic and industrial applications, evaluation of their neurotoxic effects is of major concern to public health. The aim of the present study was to evaluate the possible protective effects of Nigella sativa oil (NSO), an antioxidant agent, against PPr-induced toxicity and oxidative stress in different brain regions of rats including cerebellum, cortex and hippocampus. In the present study, 32 male Sprague-Dawley rats were used and divided into four equal groups. Group 1 was allocated as the control group. Groups 2-4 were orally administered 1 ml/kg/bw/day NSO, 8.51 mg/kg/bw/day PPr or NSO plus PPr, respectively, for 30 days. Lipid peroxidation (LPO), protein carbonyl content (PCC) and acetylcholine esterase activity (AChE) were determined. Enzymatic antioxidant activities [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione-S-transferase (GST)] and non-enzymatic antioxidants [reduced glutathione (GSH)] were determined. PPr treatment significantly increased the levels of LPO, PCC and oxidized glutathione (GSSG) in brain regions. On the contrary, levels of GSH and the activities of SOD, CAT, GSH-Px, GST and AChE were significantly decreased. NSO treatment to PPr intoxicated rats restored such biochemical parameters to within control levels except GST activity, emphasizing its antioxidant role. We conclude that NSO significantly reduces PPr-induced toxicity and oxidative stress in rat brain regions via a free radicals scavenging mechanism.     

Persistent sub-lethal chlorine exposure elicits the temperature induced stress responses in Cyprinus carpio early fingerlings

Thermal effluents discharged through cooling systems of nuclear power plants often contain chlorine (used to control bio-fouling), which may affect the metabolic status of fishes. In order to evaluate the hypothesis, we tested the effect of high temperature and a persistent sub-lethal chlorine exposure on stress responses in Cyprinus carpio advanced fingerlings. Fishes were acclimated to four different temperatures (26, 31, 33, and 36 °C) and maintained for 30 days in two different groups. Subsequently, one of the groups was exposed to persistent chlorine (0.1 mg L₋₁) for another 28 days and was compared with their respective temperature controls (without chlorine exposure). Sub-lethal doses of pollutants and increasing temperatures with in the tolerance range may not always register any morphological changes Therefore, we studied organ specific biochemical pathways viz. aspartate amino transferase, alanine amino transferase (enzymes of protein metabolism) in liver and muscle; fructose 1,6 diphosphatase (gluconeogenic pathway), in liver; pyruvate kinase, malate dehydrogenase, and lactate dehydrogenase (glycolytic pathway) in muscle; glucose-6-phosphate dehydrogenase (pentose phosphate pathway) in liver; alkaline phosphatase (phosphorus metabolism) in intestine, liver, and muscle; acetylcholine esterase (neurotransmitting enzyme) in brain, and adenosine triphosphate (for membrane transport) in gills at two different acclimation periods (14 and 28 days). The results indicate that C. carpio fingerlings demonstrated metabolic readjustments with increasing temperatures, in order to cope with energy demand of the cell. However, exposure to chlorine at higher temperatures affected protein metabolism, gluconeogenic pathway and subsequently glycolytic pathway, leading to an energy-limited condition. In addition, alteration of membrane transport and neurotransmission might be an early indication of cellular damage. Overall results indicate that persistent sub-lethal chlorine exposure elicits temperature induced stress response in C. carpio early fingerlings.     

Oxidative stress and locomotor behaviour response as biomarkers for assessing recovery status of mosquito fish, Gambusia affinis after lethal effect of an organophosphate pesticide, monocrotophos

Recovery study was performed at regular intervals to establish the time course of 50% and 100% recovery in neurotransmitter enzyme (acetylcholinesterase, AChE, EC 3.1.1.7) and locomotor behaviour response of mosquito fish, Gambusia affinis exposed to lethal concentration (20.49 mg L⁻¹) of an organophosphorous pesticide, monocrotophos (MCP) for 96 h. In vitro AChE activity studies indicated that MCP could cause 50% inhibition (I₅₀) at 10.2 × 10⁻⁵ M. A positive correlation was observed between brain AChE activity and swimming speed during the recovery study. Also, the recovery response of the antioxidant enzymes superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6) and glutathione reductase (GR, EC 1.6.4.2) as well as lipid peroxidation (LPO) as biomarkers of oxidative stress were assessed in viscera of G. affinis. The results showed that the MCP besides its inhibitory effect on target enzyme AChE activity and induction in antioxidant enzyme activities as a characteristic of oxidative stress, which can be used as biomarkers in the pesticide contaminated aquatic streams.     

Inhibition of Na-K-ATPase in different tissues of freshwater fish Channa punctatus (Bloch) exposed to monocrotophos

Freshwater fish, Channa punctatus, commonly known as the snakehead fish, was exposed to two sublethal concentrations (0.96 and 1.86 mg/L) (selected on the basis of 1/20 and 1/10 of 96 h LC₅₀ value) of monocrotophos for two exposure periods (15 and 60 days). Effects of monocrotophos on Na⁺, K⁺-ATPase in liver, kidney, muscle, intestine, brain, heart and gills were determined. Results indicate that Na⁺, K⁺-ATPase activity in tissues decreased as concentration of monocrotophos and exposure period increased. Monocrotophos induced significant inhibitory effects on the Na⁺, K⁺-ATPase activity of C. punctatus, ranging from gills (70%) > Kidney (63%) > brain (57%) > intestine (52%) > liver (50%) > muscle (47%) > heart (44%) inhibition at a sublethal concentration of 0.96 mg/L. Significant inhibition was detected in Na⁺, K⁺-ATPase activity, ranging from gills (90%) > heart (78%) > kidney (78%) > muscle (74%) > intestine (71%) > brain (67%) > liver (63%) at sublethal concentration of 1.86 mg/L. After subacute exposure (15 days) only gills and brain showed significant inhibition after higher concentration (1.86 mg/L). However, it is evident that exposure duration is more important than dose in the inhibition of the activity of enzyme. At lower concentration initial stimulation of the activity of Na⁺, K⁺-ATPase activity was also noticed. It is suggested that the inhibition of the ATPase by monocrotophos blocked the active transport system of the gill epithelial as well as chloride cells, glomerular and epithelial cells of the tubules and thus altered the osmoregulatory mechanism of the fish. In fact, the impairment of the activity of enzymes which carry out key physiological roles could cause alterations of the physiology of the whole organism.     

Toxicological and biochemical characterizations of AChE in Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae)

The toxicological and biochemical characteristics of acetylcholinesterases (AChE) in the resistant and susceptible strains (SS) of Liposcelis bostrychophila were investigated. The two resistant strains were the dichlorvos-resistant strain (DDVP-R) and the phosphine-resistant strain (PH₃-R) with resistance ratios of 22.36 and 4.51, respectively. Compared to their susceptible counterpart, the AChE activity per insect and the specific activity of AChE in DDVP-R and PH₃-R were significantly higher. There were also significant kinetic differences between DDVP-R and PH₃-R. The apparent Michaelis-Menten constant (K_m) for acetylthiocholine iodide (ATChI) was obviously lower in SS than that in PH₃-R, indicating a higher affinity to the substrate ATChI in the susceptible strains. The affinity for the substrate ATChI in DDVP-R and SS were not significantly different. The V_max value of the PH₃-R was significantly greater when compared to the V_max for the SS suggesting a possible over expression of AChE in this resistant strain. The inhibition of AChE to insecticide exposure in vitro revealed that all six insecticides were inhibitory for the extracted AChE’s. Based on the I₅₀ values, AChE of the SS were more sensitive to dichlorvos, paraoxon-ethyl, malaoxon and demeton-S-methyl than those of the two resistant strains. As for carbaryl and eserine, the PH₃-R suggested a significantly higher I₅₀s compared to the susceptible strain, while, no significant differences were found between SS and DDVP-R.     

Biochemical alteration induced by monocrotophos in the blood plasma of fish, Channa punctatus (Bloch)

Monocrotophos (MCP), commonly known as azodrin, is one of the organophosphate (OP) pesticides extensively used in agricultural practices throughout the world. Channa punctatus were exposed to sublethal concentrations (0.96 and 1.86 mg/L) of monocrotophos for 15 and 60 days to assess the alterations in the level of some biochemical parameters in blood plasma. Significant alterations in all the biochemical parameters were found to be dose dependent. Hypoglycemia and hypocholesteremia were observed in plasma of fish at both exposure periods (15 and 60 days). Increased activities of glutamate-oxalacetate transaminase (GOT), glutamate-pyruvate transaminase (GPT), acid and alkaline phosphatase of blood plasma indicated hepatic tissue damage. Decrease in lactate dehydrogenase (LDH) content in plasma further indicated lower metabolic rate after 60 days of exposure. Significant decline in triglycerides content was observed in fish exposed to both sublethal concentrations of monocrotophos. We suggest that analysis of biochemical parameters in the fish blood may be useful in environmental biomonitoring.