Acute, chronic and sublethal effects of the herbicide propanil on Daphnia magna.

Acute and chronic toxicity tests with propanil were conducted on Daphnia magna. The 24 and 48 h LC50 were 43.74 and 5.01 mg/l respectively. Chronic toxicity tests were carried out using sublethal propanil concentrations (0.07, 0.10, 0.21 and 0.55 mg/l) during 21 days. The effect of propanil on survival, reproduction and growth of D. magna organisms was monitored. The parameters used to evaluate herbicide effect on reproduction were: mean total young ones per female, mean brood size, time to first reproduction, mean number broods per female and intrinsic rate of natural increase (r). Survival and growth (body length) were also determined after 21 days of exposure to the herbicide. Reproducti…

Alterations on AChE Activity of the Fish Anguilla anguilla as Response to Herbicide-Contaminated Water

Abstract The inhibition of both total and specific acetylcholinesterase activities was measured in the whole eyes of the yellow eel Anguilla anguilla after exposure to the carbamate thiobencarb. In vivo assays were conducted under a constant flow-through system of thiobencarb-contaminated water (1/60 LC50 96 h=0.22 ppm for 96 h) followed by a recovery period in clean water (192 h more). The results indicated a measurable level of AChE activity on eyes of control eels, which resulted in a sensitive indicator of the presence of thiobencarb in the water. The pesticide induced significant inhibitory effects on AChE activity ranging from 35% in total AChE activity to 75% in specific AChE activit…

Cholinesterase Activity and Hematological Parameters as Biomarkers of Sublethal Molinate Exposure in Anguilla anguilla

Cholinesterase (ChE) activity was measured in plasma, whole blood [using 5,5'-dithiobis(2-nitrobenzoic acid) and 2-PDS as chromophores], brain, and whole eyes of Anguilla anguilla exposed to a sublethal concentration of 11.15 mg/L (one-third of the 96-h LC(50)) of the carbamate herbicide molinate. ChE activity was evaluated after 6, 24, 48, 72, and 96 h of pesticide exposure. Results indicated that ChE activity in eel tissues decreased as time of exposure increased, especially in eel blood. Eels exposed to molinate were transferred to a pesticide-free water for a recovery period of 4 days and ChE activity was also evaluated. Results indicated that ChE activity for those animals with preexpo…

Energy reserves mobilization in the yellow eel as herbicide exposure effect.

Abstract Thiobencarb and propanil are two of the most extensive used herbicides worldwide in rice cultivation. Especially scanty is the available information regarding the effect of herbicides on fish energy resources. In the present study, the effect of sublethal exposure to these herbicides on the energy reserves of juvenile eel Anguilla anguilla was compared. Eels were exposed to 72 h to the herbicide thiobencarb (0.22 mg L −1 ) or Propanil (0.63 mg L −1 ), and allowed to recover in clean water (144 h). Caloric content was determined in liver and skeletal muscle. Fish exposed to thiobencarb rapidly mobilized energy. Reserves from liver were depleted (21%) compared to control values (2.50…

Physiological Perturbations in Several Generations of Daphnia magna Straus Exposed to Diazinon

Abstract Daphnia magna was exposed to sublethal diazinon concentrations (0.05, 0.1, 0.5, 0.75, and 1.0 ng/L) for 21 days. The algae Nannochloris oculata (5×10 5 cells/mL) was used to feed the daphnids. Chronic toxicity tests were carried out using neonates of F 1 (first brood) and F 1 (third brood) offspring generations from parentals (F 0 ) preexposed to the organophosphate. The effect of diazinon on survival, reproduction, and growth was monitored for the selected daphnid generations. The parameters used to evaluate pesticide effect on reproduction were mean total young per female, mean brood size, time to first reproduction, mean number broods per female, and intrinsic rate of natural in…

An approach to the diazinon toxicity in the European eel: bioaccumulation studies

Abstract The acute toxicity effects of diazinon on European eel ( Anguilla anguilla ) were examined using short-term exposures in static conditions. In these conditions the 96-h median lethal concentration (LC 50 ) was 0.086 mg/1. In addition, the eels were exposed to two sublethal diazinon concentrations, 0.042 and 0.056 mg/1 (1/2 and 2/3 LC 50 96-h, respectively) for different exposure times, till a maximum of 96 h, and bioaccumulation and clearance of this insecticide in liver, muscle, gill and blood tissues were studied. BCF values of diazinon after 96 h exposure to 0.042 mg/l were 1850 in liver, 875 in gill and 775 in eel muscle. BCF values of diazinon over a 48-h exposure period to 0.…

Effect of the lipid regulator Gemfibrozil in the Cladocera Daphnia magna at different temperatures.

ABSTRACTIn the present study, an ecotoxicological approach to the evaluation of Gemfibrozil (GEM) as an emerging organic pollutant was done. In order to assess its toxicity, tests were conducted using the cladocera Daphnia magna. Experiments were carried out at 22°C and 28°C. EC50, feeding behavior, and chronic toxicity tests (21 days) were evaluated in D. magna exposed to GEM as well as cholesterol levels at 21-day chronic exposure. D. magna GEM EC50 values (24 h) in our experimental conditions were 148.75 and 116.24 mg L−1 at 22°C and 28°C, respectively. Test concentrations of 0.1, 0.5, 1.0, 5.0 and 7.5 mg L−1 were selected for subacute and chronic experiments. Subacute short-term test (f…

Assessment of chronic effects of tebuconazole on survival, reproduction and growth of Daphnia magna after different exposure times

The effect of the fungicide tebuconazole (0.41, 0.52, 0.71 and 1.14mg/L) on survival, reproduction and growth of Daphnia magna organisms was monitored using 14 and 21 days exposure tests. A third experiment was performed by exposing D. magna to the fungicide for 14 days followed by 7 days of recovery (14+7). In order to test fungicide effects on D. magna, parameters as survival, mean whole body length, mean total number of neonates per female, mean number of broods per female, mean brood size per female, time to first brood/reproduction and intrinsic rate of natural increase (r) were used. Reproduction was seriously affected by tebuconazole. All tebuconazole concentrations tested affected t…

In vivo inhibition of AChE activity in the European eel Anguilla anguilla exposed to technical grade fenitrothion.

European eel (Anguilla anguilla) were exposed to sublethal fenitrothion concentrations in a continuous flow-through system for 4 days. Plasma acetylcholinesterase (AChE) activity was evaluated after 2, 8, 12, 24, 32, 48, 56, 72 and 96 h pesticide exposure. AChE activity in the plasma of the eel decreased as concentration of fenitrothion increased. Pesticide induced significant inhibitory effects on the AChE activity of A. anguilla ranging from 51% inhibition at sublethal concentration of 0.02 ppm to 57% inhibition at sublethal concentration of 0.04 ppm. Eel were exposed to both fenitrothion concentrations for 96 h and then allowed a period of recovery in pesticide-free water. Following 1 we…

Daphnia magna feeding behavior after exposure to tetradifon and recovery from intoxication.

Abstract The feeding behavior of the cladocera Daphnia magna subjected to a short-term exposure to the acaricide tetradifon (4-chlorophenyl 2,4,5-trichlorophenyl sulfone) was studied. The experiments were performed using the unicellular algae Nannochloris oculata at a density of 5×10 5 cells/ml as food for the organisms. In a first experiment, three generations (F0, F1, and F3) of the daphnids were exposed to sublethal levels of tetradifon (0.1, 0.18, 0.22, and 0.44 mg/l) and the effect of the toxicant on filtration and ingestion rates was determined. Rates of filtration and ingestion of D. magna declined in the three generations studied with increasing toxicant concentrations; however, tox…

Thiobencarb-Induced Changes in Acetylcholinesterase Activity of the Fish Anguilla anguilla

Abstract European eels (Anguilla anguilla) were exposed to sublethal thiobencarb concentrations in a continuous flow-through system for 4 days. Brain, muscle, and gill acetylcholinesterase (AChE) activities were evaluated after 2, 12, 24, 48, 72, and 96 h herbicide exposure. Thiobencarb induced significant inhibitory effects on the total and specific AChE activity of A. anguilla, ranging from >30–40% inhibition in eel brain and gills to >50% inhibition in muscle tissue 2 h after the initial exposure. In a second experiment, eels were exposed to thiobencarb for 96 h and then allowed a period of recovery in pesticide-free water. Following 1 week of recovery, the AChE activity of affected eels…

Caloric content of Daphnia magna as reflect of propanil stress during a short-term exposure and its relationship to long-term responses

The present study investigates energy stores changes in the aquatic invertebrate Daphnia magna following a 5-d exposure to propanil. Juveniles of D. magna were exposed to sublethal propanil concentrations (0.07, 0.10, 0.21 and 0.55 mgl(-1)) which were used previously to test their effect on reproduction, growth and survival (21 days test) of D. magna. Glycogen, total lipids, proteins, and dry weight were determined in control and exposed daphnids at 24, 48, 72, 96 and 120 h. Data were used to calculate caloric content as biomarker of propanil exposure. Results showed a depletion of energy reserves in D. magna exposed to the herbicide. At 120 h of exposure to the highest propanil concentrati…

Comparative study of the toxicity of molinate for freshwater organisms.

Inhibition of Gill Na+,K+-ATPase Activity in the Eel,Anguilla anguilla,by Fenitrothion

European eels (Anguilla anguilla) were exposed to sublethal fenitrothion concentrations (0.02 and 0.04 mg/liter) in a continuous flow-through system for 4 days. Gill Mg2+- and Na+,K+-ATPase activities were evaluated after 2, 8, 12, 24, 32, 48, 56, 72, and 96 h of pesticide exposure. Results indicated that ATPase activity in gill tissue decreased as concentration of fenitrothion increased. Pesticide induced significant inhibitory effects on the Na+, K+-ATPase activity of A. anguilla, ranging from >56% inhibition at a sublethal concentration of 0.02 ppm to >73% inhibition at a sublethal concentration of 0.04 ppm. Eels were exposed to both fenitrothion concentrations for 96 h and then allowed …

Effects of propanil on the European eel Anguilla anguilla and post-exposure recovery using selected biomarkers as effect criteria

Abstract The aim of this study was to assess the physiological response of Anguilla anguilla to propanil and the degree of recovery after being moved to clean water. Preliminary acute toxicity test was carried out in the laboratory and the median lethal concentration (LC50) at 96 h was calculated as 31.33 mg/L (29.60–33.59 mg/L). NOEC and LOEC values (at 96 h) were also calculated as 20 and 25 mg/L, respectively. The fish were exposed to 0.63 and 3.16 mg/L of propanil for 72 h and allowed to recover for 144 h. Total proteins (TPs), γ -glutamil transpeptidase ( γ -GT), alanin aminotransferase (AlAT), alkaline phosphatase (AP), lactate dehydrogenase (LDH) and water content (WC) were assayed i…

Fenitrothion uptake and bioconcentration in the European eel(Anguilla anguilla)

Eels (Anguilla anguilla) were exposed to 0.02 mg/L of the organophosphorus pesticide fenitrothion during 144 hours in semi‐static conditions. BCF, intBCF, uptake rate constants (Ku) and elimination rate constants (Kd) of fenitrothion were determined in brain, gills, blood and muscle tissues of the eel. A simple one‐compartment model fitted the uptake and elimination characteristics. Plateau were reached at different times in the different tissues: at 24 hr in gills, 72 hr in brain and blood and 120 hr in muscle tissue. BCF were ranged from 117 for blood to 658 for muscle. Muscle tissue showed the highest BCF, intBCF, Ku and the lowest Kd .

Effect of an Acaricide on the Reproduction and Survival of Daphnia magna

Sublethal Effects of an Organophosphate Insecticide on the European Eel,Anguilla anguilla

The present communication deals with the effects of fenitrothion (0.02 mg/liter) on the energy metabolism of the European eel, Anguilla anguilla, and its recovery from intoxication. Various parameters such as glycogen, lactate, proteins, and glucose levels were measured in different eel tissues after 2, 8, 12, 24, 32, 48, 56, 72, and 96 hr of fenitrothion exposure. Subsequently, the fish were allowed recovery periods of 8, 12, 24, 48, 72, 96, 144, and 192 hr in clean water, and the same parameters were evaluated. Liver glycogen content showed no significant changes during the exposure time, while blood glucose levels increased markedly. Gill, liver, and blood lactate values increased during…

Accumulation of Tetradifon in an Algae ( Nannochloris oculata ) and the Cladoceran, Daphnia magna

Chronic toxicity of fenitrothion to an algae (Nannochloris oculata), a rotifer (Brachionus calyciflorus), and the cladoceran (Daphnia magna).

Chronic toxicity studies were conducted with an algae (Nannochloris oculata), a rotifer (Brachionus calyciflorus), and a cladoceran (Daphnia magna) to determine their relative sensitivities to the organophosphorus insecticide fenitrothion. The cladoceran D. magna was the most sensitive of the three species. The no observed effect concentrations (NOECs) for the study with the algae (1.0 mg/liter) and for the rotifer (1.0 mg/liter) were higher than the NOEC (0.009 microgram/liter) and the LC50 of 24 hr (0.067 microgram/liter) for D. magna. Most of the algal populations were not initially affected by exposure to fenitrothion. Pesticide concentrations higher than 1.0 mg/liter significantly redu…

Effects of tetradifon on Daphnia magna during chronic exposure and alterations in the toxicity to generations pre-exposed to the pesticide.

Daphnia magna was exposed to some nominal sublethal tetradifon concentrations (0.10, 0.18, 0.22 and 0.44 mg/l) during 21 days. Chronic toxicity tests were carried out using neonates of F(1) first brood (F(1)-1st) and F(1) third brood (F(1)-3rd) offspring generations from parentals (F(0)) pre-exposed to the pesticide. The effect of tetradifon on survival, reproduction and growth was monitored for the selected daphnid generations. The parameters used to evaluate pesticide effect on reproduction were: mean total young per female, mean brood size, time to first reproduction, mean number broods per female and intrinsic rate of natural increase (r). Survival and growth (body length) were also det…

Assessment of the toxicity of a pesticide with a two-generation reproduction test using Daphnia magna.

Abstract Daphnia magna (F 0 generation) were exposed during 21 days to different diazinon concentrations. Offspring (animals from the first and third brood: F 1 (1st) and F 1 (3rd), respectively) were transferred to a free pesticide medium during a 21-day recovery period. The algae Nannochloris oculata (5×10 5 cells/ml) were used as food. In this recovery study, survival, growth and reproduction (mean total young per female, mean brood size, onset of reproduction and mean number broods per female) were assessed as individual parameters, and the intrinsic rate of natural increase ( r ) as population parameter for F 1 (1st and 3rd broods) daphnids. Reproduction as well as survival was still r…

European eel (<i>Anguilla anguilla</i>) plasma biochemistry alerts about propanil stress

Propanil stress response in the eel (Anguilla anguilla) was examined. Eels were exposed to 3.16 mg/L for 72 hr and allowed to recover for 96 hr. Plasma levels of cortisol, lactate dehydrogenase (LDH), alkaline phosphatase (AP), aspartate aminotransferase (AST), cholesterol, triglycerides, glucose, ammonium, lactate, albumin, and total proteins as well as electrolytes (chloride, sodium, potassium, calcium and phosphorus) were determined. As a consequence of exposure, cortisol, AP, AST, and LDH increased. A hyperglycemic condition, together with hyperlactemia, hypoalbuminemia, hypoproteinemia, hypercholesterolemia and hypertriglycemia was registered. Ammonium increased during exposure concomi…

Role of glutathione in Thiobencarb resistance in the European eel Anguilla anguilla.

Glutathione-dependent defense against xenobiotic toxicity is a multifaceted phenomenon that has been well characterized in mammals. In the present study, eels of species Anguilla anguilla were exposed to 15 ppm of the herbicide thiobencarb (S-4-chlorobenzyl diethylthiocarbamate) for 96 h. Eels exposed to the pesticide were grouped in 24-h intervals according to their time of death, while surviving intoxicated eels constituted another group (live animals). Glutathione content (GSx, GSH, GSSG) was determined in liver and muscle tissues of the dead and live (intoxicated) animals and compared to control values (nonexposed eels). The fish that died before 96 h of exposure were considered suscept…

EFFECTS OF THIOBENCARB HERBICIDE TO AN ALGA (NANNOCHLORIS OCULATA) AND THE CLADOCERAN (DAPHNIA MAGNA)

Chronic toxicity studies were conducted with an algae (Nannochloris oculata) and the cladoceran (Daphnia magna) to determine their relative sensitivities to the thiocarbamate herbicide thiobencarb (S-4-chlorobenzyl diethylthiocarbamate). Most of the algal populations were initially affected by exposure to the herbicide. Thiobencarb concentrations higher than 0.5 mg/L significantly reduced algal densities after 24-h exposure. The 24-h static EC50 in D. magna was 3.01 mg/L. The sublethal effects of 0.3, 0.37, 0.5, 0.75, and 1.5 mg/L of thiobencarb concentrations on the survival, reproduction, and growth of D. magna were monitored for 21 days. The parameters used to determined the effect of th…

Physiological Effects of Thiobencarb Stress in the Eel (<i>Anguilla anguilla</i>)

ヨーロッパウナギ Anguilla anguilla の代謝系へのチオベンカルブの影響と, 中毒からの回復とを評価した. 暴露期間ならびにそれに続く非汚染水中での8日間のウナギの血漿, 筋肉, 肝臓についてグリコーゲン, 脂質およびタンパクを測定した. 暴露により血糖値の上昇が認められたが, 肝臓と筋肉におけるグリコーゲンレベルは著しく低下した. 血中の脂質は増加したが, 肝臓での脂質は顕著に減少した. タンパク質の易動化は, とくに筋肉組織で認められた. ほとんどの代謝障害は, 非汚染水へ移した8日後まで継続した. 以上のチオベンカルブの代謝系への影響はある種のストレス症状であり, 魚類の農薬ストレスを代償しようとする生理的適応の具体例と考えられた.

Response and Recovery of Brain Acetylcholinesterase Activity in the European Eel,Anguilla anguilla,Exposed to Fenitrothion

European eel (Anguilla anguilla) were exposed to sublethal fenitrothion concentrations in a continuous flow-through system for 4 days. Brain acetylcholinesterase (AChE) activity was evaluated after 2, 8, 12, 24, 32, 48, 56, 72, and 96 h pesticide exposure. Results indicated that AChE activity in eel brains decreased as the concentration of fenitrothion increased. The pesticide induced significant inhibitory effects on the AChE activity ofA. anguilla,ranging from >40% inhibition at a sublethal concentration of 0.02 ppm to >60% inhibition at a sublethal concentration of 0.04 ppm. Eel were exposed to both fenitrothion concentrations for 96 h and then allowed a period of recovery in pesticide-f…

Physiological stress responses ofAnguilla anguillato fenitrothion

The present communication deals with the effect of fenitrothion (0.04 ppm) on the carbohydrate metabolism of the european eel Anguilla anguilla and its recovery from intoxication. Analysis of various parameters such as glycogen, lactate and glucose was made on different eel tissues after 2, 8, 12, 24, 32, 48, 56, 72 and 96 hr of fenitrothion exposure. Subsequently, the fish were allowed recovery periods of 8, 12, 24, 48, 72, 96, 144 and 192 hr in clean water, and the same parameters were evaluated. Muscle glycogen content decreased significantly during the exposure time, while blood glucose levels increased markedly. Gill, muscle and blood lactate values increased during pesticide exposure.…

Bioconcentration and excretion of diazinon by eel.

Physiological effects of tricyclazole on zebrafish (Danio rerio) and post-exposure recovery

Short-term effects of tricyclazole on male zebrafish (Danio rerio) physiology were examined joint to the degree of recovery after exposure. Fish were exposed to 142 microg/L (1/100 LC(50)-96 h) of tricyclazole for 7 (Exp.1) and 14 days (Exp.2) and then allowed to recover for 7 or 14 more days, respectively. Whole-body triglycerides, cholesterol, glucose, lactate and total proteins were measured as well as the aspartate aminotransferase (AAT), alanine aminotransferase (AlAT), alkaline phosphatase (AP) and lactate dehydrogenase (LDH) activities as biomarkers of intermediary metabolism; gamma-glutamyl transpeptidase (gammaGT) as biomarker of oxidative detoxification processes and vitellogenin …

Sublethal bioconcentration of fenitrothion in the blood and brain of the european eel.

Disturbances in energy metabolism of Daphnia magna after exposure to tebuconazole.

Abstract This study was conducted to investigate the change of some biochemical parameters in the aquatic invertebrate Daphnia magna following exposure to the fungicide tebuconazole and to determine the most sensitive biomarker among the ones tested in this species. Four biochemical biomarkers (protein, glycogen, lipids and caloric content) were correlated with feeding behaviour studies of D. magna after fungicide exposure. Juveniles of D. magna were exposed to four sublethal concentrations of tebuconazole (0.41, 0.52, 0.71 and 1.14 mg L−1) for 5 d. Daphnid samples were taken from each test and control group at 24, 48, 72, 96 and 120 h after the start of the experiment. Tebuconazole EC50 va…

Changes in carbohydrate metabolism in the eelanguilla anguilla, during short‐term exposure to diazinon

The present communication deals with the effect of diazinon (0.042 mg/L) on the energy metabolism of the european eel Anguilla anguilla. Analysis of various parameters such as glycogen, lactate and glucose was made on different eel tissues after 6, 24, 48, 72 and 96 hr of diazinon exposure. Liver and muscle glycogen content decreased significantly (p < 0.05) from 6 to 96 hr pesticide exposure. Mean blood glucose values were elevated significantly after exposure to this sublethal diazinon concentration. Liver, blood and muscle lactate levels in fish increased during all exposure time being the highest at 96 hr exposure. Diazinon intoxicated fish showed signs of pesticide poisoning as muscula…

Population dynamics in Daphnia magna as modified by chronic tetradifon stress.

Two Daphnia magna offsprings (animals from the first and third brood) whose parentals (F0-generation) were exposed during 21 days to different tetradifon (4-chlorophenyl 2,4,5-trichlophenyl sulfone) concentrations, were transferred to a pesticide free medium during 21 days (recovery period). The algae Nannochloris oculata (5 x 10(5) cells/mL) was used as food. In this recovery study, survival, growth and reproduction (mean total young per female, mean brood size, onset of reproduction and mean number broods per female) were assessed as individual parameters and the intrinsic rate of natural increase (r) as population parameter, for F1 generation (1st and 3rd broods). Reproduction was still …

Pesticide toxicokinetics in fish: accumulation and elimination.

Bioaccumulation of fenitrothion in the European eel (Anguilla anguilla) was studied using two sublethal concentrations of this pesticide in a flow-through test system. The pesticide concentrations used were one-tenth (0.002 ppm) and one-fifth (0.04 ppm) the 96-h LC50 of fenitrothion in this species. Steady state was reached early (2 h) when the animals were exposed to 0.02 ppm of toxicant, and after 48 h when the animals were exposed to 0.04 ppm. Toxicokinetic parameters for fenitrothion in eel muscle (K1, K2, and T1/2) were calculated for both experiments. The highest bioconcentration factor was calculated for animals exposed to 0.04 ppm of toxicant, indicating the relationship between the…

Liver energy metabolism of Anguilla anguilla after exposure to fenitrothion.

This paper deals with the effect of fenitrothion (0.04 mg/liter) on the energy metabolism of the European eel, Anguilla anguilla, and its recovery from intoxication. Various parameters such as glycogen, lactate, proteins, total lipids, and glucose in eel liver and blood were analyzed after 2, 8, 12, 24, 32, 48, 56, 72, and 96 h of fenitrothion exposure. Subsequently, the fish were allowed recovery periods of 8, 12, 24, 48, 72, 96, 144, and 192 h in clean water, and the same parameters were evaluated. Liver glycogen and lipid contents decreased significantly during the exposure, while blood glucose levels increased markedly. Liver and blood lactate values increased during pesticide exposure,…

Short-term exposure to sublethal tebuconazole induces physiological impairment in male zebrafish (Danio rerio).

Abstract The aim of the present study was to assess the physiological response of male zebrafish Danio rerio to the fungicide tebuconazole and recovery in fungicide-free water. Acute toxicity tests were carried out and the median lethal concentration (LC 50 ) from 24 to 96 h was calculated. The fish were exposed to a sublethal fungicide concentration of 230 μg/L for 7 or 14 days and allowed to recover for 7 or 14 more days, respectively. Whole-body levels of vitellogenins, triglycerides, cholesterol, glucose, lactate and proteins as well as the activities γ-glutamil transpeptidase (γ-GT), alanin aminotransferase (AlAT), alkaline phosphatase (AP) and lactate dehydrogenase (LDH) were assayed;…

Biochemical stress response in tetradifon exposed Daphnia magna and its relationship to individual growth and reproduction

Abstract Environmental risk assessment of chemicals toxicity requires the use of costly and labor-intensive chronic data and short-term tests provide additional information. Energy budget is used by the animals for their growth, reproduction, and metabolism and it is reduced in case of toxic stress. Tetradifon acaricide is frequently used in the European Mediterranean region and it is implicated in aquatic environmental pollution. Previous studies showed that the EC50-24 h of tetradifon on Daphnia magna was 8.92 mg/L. Based on that, D. magna were exposed to sublethal tetradifon concentrations of 0.10, 0.18, 0.22 and 0.44 mg/L for five days in order to investigate their effect on intermediat…

Effects of diazinon exposure on cholinesterase activity in different tissues of European eel (Anguilla anguilla).

Cholinesterase (ChE) activity was measured in brain, plasma, and whole eye of Anguilla anguilla experimentally exposed to a sublethal concentration of 0.042 mg/liter (0.50 of the 96-hr LC50) of the organophosphorous pesticide diazinon. Whole eye was the tissue which revealed higher values of ChE activity (8.17 micromol/min/g) in nonexposed animals. Brain, plasma, and whole eye ChE activity of A. anguilla was inhibited at 6, 24, 48, 72, and 96 hr of diazinon exposure. Pesticide induced significant inhibitory effects on the ChE activity of this species ranging from >70% inhibition in brain tissue to >90% in plasma samples. Brain and plasma presented technical difficulties in their collection.…