In vitro kinetic characterization of inhibition of acetylcholinesterase by organophosphate and carbamate compounds in food animals

Organophosphate, dichlorvos (2,2-dichlorovinyldimethylphosphate, DDVP), and diazinon (DZN) as well as carbamates are currently found in contaminated water, dust, soil, agricultural waste, and elsewhere in the environment, and can be harmful after accidental or deliberate exposure. Intoxication by these compounds causes a generalized cholinergic crisis due to the inhibition of acetylcholinesterase (AChE), whose major physiological role in mammalian tissues is in nervous transmission. The half-maximal inhibitory concentration (IC₅₀) was found to be higher for carbaryl than DDVP and DZN, about 3–4 times in liver and about 4–6 times in muscles. The half time (t _1/2) of inhibition (8?µmol?L^?1 DDVP or DZN; 40?µmol?L^?1 carbaryl) ranged between 4 and 16?min and decreased as follows: pig?>?cattle?>?sheep for liver tissue, and cattle?>?sheep?>?pig for muscle. Rate constants of inhibition (k _i) ranged between 43?×?10^?3 and 168?×?10^?3?min^?1 for liver and from 46?×?10^?3 to 115?×?10^?3?min^?1 for muscles. Very little residual AChE activity (<6.1%) was seen in liver, but more was seen in muscle (<17%).     

The role of root organic acids in the tolerance of Festuca rubra to zinc,lead and cadmium

Abstract

Festuca rubra L. plants are pseudometallophytes colonizing abandoned Pb/Zn mine areas, successfully employed in phytostabilization. To study the contribution of low-molecular weight organic acids to metal tolerance, F. rubra plants were grown for three months in hydroponics with Cd (1.8, 18 and 36 µmol?L^?1), Pb (50, 250 and 500?µmol?L^?1) and Zn (0.3, 3 and 6?mmol?L^?1), separately, and in ternary combination (18?µmol?L^?1 Cd + 250?µmol?L^?1 Pb + 0.3?mmol?L^?1 Zn). The roots retained most of the metals but their distribution from shoot to root was altered when the plants were treated with the ternary combination. The main organic acids in roots were citrate and malate. At the lowest concentrations, the metals caused small reductions in biomass, had no effects on photosynthetic pigments nor on malondialdehyde, but led to increases in root organic acids. At higher concentrations, phytotoxic responses were observed, associated with a decline of citrate and malate in the roots.     

Silver nanoparticles toxicity effect on photosystem II photochemistry of the green alga Chlamydomonas reinhardtii treated in light and dark conditions

The inhibitory effect of silver nanoparticles (AgNPs) on photochemical reactions of photosynthesis was investigated using the green alga model Chlamydomonas reinhardtii. Algal cells were exposed to 1, 5, and 10?µmol?L^?1 of AgNPs under both light and dark conditions during 6?h. The rapid rise of chlorophyll a fluorescence and the fluorescence imaging system were employed to investigate the alteration of photosystem II (PSII) photochemical reactions and the associated electron transport activity. When algal cells were exposed to 5 and 10?µmol?L^?1 of AgNPs, our results showed the evidence of a structural deterioration of PSII reaction center, the alteration of the oxygen evolving complex and the inhibition of electron transport activity, which was stronger for AgNPs treatment under light exposure. Under these conditions, there was no activation of regulated photoprotective mechanisms against excess absorbed light-energy by the antenna system of the PSII complex. The highest deteriorating effect on the structural and functional integrity of PSII was observed for algal cells exposed 6?h in light condition to 10?µmol?L^?1 of AgNPs. Therefore, we provide valuable data in this study permitting to use photosynthetic-based fluorescence parameters for aquatic toxicological risk investigation of polluted water that may contain AgNP suspension.     

Toxic effects of phosphoramidate on Paramecium sp. with special emphasis on respiratory metabolism,growth, and generation time

The toxicological impacts of the increasing number of synthetic compounds present in the aquatic environment are assessed predominantly in laboratory studies where test organisms are exposed to a range of concentrations of single compounds. Protozoan cells are often used as bioindicators for the presence of xenobiotic compounds. In this article, we describe the inhibitory effect of a synthetic phosphoramidate derivative at different concentrations (40, 60, and 80?µmol?L^?1) on Paramecium sp., affecting its growth (proliferation) in concentration-dependent manner, as well as the generation time and response percentage. The LC₅₀ value determined for these protozoa was estimated at 60?µmol?L^?1 on 24?h of exposure. The respiratory metabolism of protozoan is perturbed at three concentrations, noting that the oxygen consumption was significantly increased at high concentrations after 18?h of exposure. In addition, the data can be used as reference values in further testing with other pesticides.     

Seasonal changes in inorganic nutrient concentration in the alexandria western harbour (Egypt)

Surface and bottom water samples were collected on a monthly basis from six locations in the Alexandria Western Harbour between April 2002 and March 2003. Total nitrogen, ammonia, nitrite, nitrate, total phosphorus, reactive phosphate and silicate were analysed. The average content of total nitrogen ranged from 81.1 to 65.7?µmol?l^?1 in the surface and bottom waters, respectively, while ammonia ranged from 13.77 to 15.79?µmol?l^?1 in surface and bottom waters, respectively. Also, the average concentration of nitrite was relatively higher in surface waters than in bottom waters (0.89 and 0.61?µmol?l^?1, respectively). The results of this study also indicated a considerable temporal variation in nitrate concentrations which ranged from 1.12 to 13.83?µmol?l^?1. Total phosphorus displayed an irregular pattern throughout the year, ranging from 1.9 to 11.8?µmol?l^?1 in surface waters and from 1.7 to 9.1?µmol?l^?1 in bottom waters. The results of PO₄-P analysis showed higher values in surface waters (0.28–2.75?µmol?l^?1) than in bottom waters (0.10–1.70?µmol?l^?1). The average concentration of silicates was relatively lower in the surface than in the bottom waters (8.97 and 10.1?µmol?l^?1, respectively). The analysis of variance (ANOVA) among seasons and sites revealed significant differences for ammonia, total nitrogen and phosphate, while nitrate showed no significant differences among stations. Finally, silicate did not show any significant variance among sites and seasons (ANOVA, P?>?0.05).     

Effects of bisphenol A on Gammarus fossarum and Lumbriculus variegatus in artificial indoor streams

The impact of bisphenol A (BPA) on Gammarus fossarum and Lumbriculus variegatus was studied in four artificial indoor streams (0, 5, 50 and 500?µg?L^?1 BPA, nominal) over 103 days in a pulse–dose exposure scenario (weekly BPA application). For G. fossarum populations at day 103, the proportions of juveniles and of breeding females from the highest BPA treatment were in tendency reduced. For individually exposed gammarid pairs an EC₁₀ of 17?µg?L^?1 BPA (nominal) for the proportion of reproductive females in the fourth brood was determined. During the first three broods, the largest brood size occurred at the highest BPA concentration, whereas in the fourth brood it decreased concentration-dependently (fourth brood EC₁₀?=?5?µg?L^?1 BPA, nominal). Effects on L. variegatus were a reduced population growth (103?d-EC₁₀ of 2?µg?L^?1 BPA, nominal) and an increase in dry weight and the number of segments in large, complete worms.     

Cytotoxicity of benalaxyl,metalaxyl, and triadimefon on Chinese hamster ovary cells

The cytotoxicity of the fungicides benalaxyl, metalaxyl, and triadimefon was evaluated in vitro using the Chinese hamster ovary (CHO-K1) cell line. The midpoint cytotoxicity values of neutral red (NR) incorporation (NRI₅₀), total cellular protein content (TCP₅₀), and the methyl tetrazolium assay (MTT₅₀) were estimated. Benalaxyl was the most cytotoxic fungicide, followed by metalaxyl and triadimefon. Fetal calf serum (10%) caused a reduction in benalaxyl, metalaxyl, and triadimefon cytotoxicity by factors of 1.8, 1.3, and 1.3. The effects of sublethal concentrations (NRI₂₅) of the three fungicides on the glutathione redox cycle components glutathione S-transferase, glutathione reductase, glutathione peroxidase, and total glutathione content were studied. The ameliorative effects of extracellular glutathione (1 mmol L^?1), vitamin C (70 µmol L^?1), and vitamin E (30 µmol L^?1) were also investigated. The three antioxidants led to significant effects on the glutathione redox cycle components.     

Toxicokinetics,metabolism, and microsomal studies of chlorpropham in rats

A study on the toxicokinetic behavior, metabolism of chlorpropham, and its effect on cytochrome P₄₅₀ from liver microsomes was carried out in albino rats after a single and consecutive oral administration at 500?mg?kg^?1 body weight for 10 and 20 days. Chlorpropham was detected in the blood at 0.08?h (11.43?±?1.72?µg?mL^?1) reaching a maximum concentration at 2?h (30.90?±?2.55?µg?mL^?1) and a minimum at 48?h (1.95?±?0.20?µg?mL^?1) after a single oral administration of 500?mg?kg^?1. The absorption rate constant (K _a) was 0.66?±?0.48?h^?1. The Vd _area (18.01?±?2.78?L?kg^?1) and t _1/2 β (12.23?±?1.96?h) values suggested a wide distribution and long persistence of the compound in the body, respectively. The higher Cl_R (0.82?±?0.00?L?kg^?1?h^?1) compared to Cl_H (0.18?±?0.02?L?kg^?1?h^?1) value indicated that a major portion of chlorpropham was excreted through the urine (30%) compared to the faeces (2.81%). Chlorpropham residue was detected in all tissues of rat at 0.25?h while its metabolite, meta-chloroaniline was detected in liver, kidney, heart, lung, and spleen tissue at 0.25?h. Meta-chloroaniline was not detected in skeletal muscle, brain, fat, and stomach tissue at any time of the observation period. Maximum concentrations of chlorpropham and meta-chloroaniline were detected at 2?h (except in the spleen), and minimum concentrations of chlorpropham at 24 (heart, lung, spleen, skeletal muscle, and stomach) and 48?h (liver, kidney, brain, and fat tissue) respectively; and meta-chloroaniline at 24?h (except heart and spleen). The tissue half-life of chlorpropham in rat varied from 3.80 to 11.60?h. Repeated oral administration of chlorpropham at 500?mg?kg^?1 for 10 and 20 days caused an induction of the liver microsomal pellet of rat.     

Effects of copper on lipid peroxidation,glutathione, metallothionein,and antioxidative enzymes in the freshwater mussel Anodonta anatina

Copper is an essential element to all animals. At elevated concentrations, it is toxic and can participate in the formation of reactive oxygen species, leading to cellular damage. In this study, the ecotoxicological relevance of copper was investigated with freshwater mussels, Anodonta anatina. When the mussels were exposed to copper at environmentally realistic concentrations, either via the water (0.3?µmol?L^?1 Cu) or fed with Cu-loaded algae (equivalent to 0.06?µmol?L^?1 Cu), the level of thiobarbituric acid-reactive substances rose and glutathione decreased. This was associated with the induction of metallothionein and, relative to total protein, of glutathione reductase and the antioxidative enzymes superoxide dismutase, catalase, and glutathione peroxidase. But, since the overall protein-synthetic capacity was hampered by the copper insult, the activities of the enzymes relative to tissue weight and copper concentrations were depressed. During depuration, most parameters started to normalize although not returning to control values within 12 days.     

Toxicity of endosulfan on growth,photosynthesis, and nitrogenase activity in two species of Nostoc (Nostoc muscorum and Nostoc calcicola)

Treatments of the cyanobacteria Nostoc muscorum and Nostoc calcicola with the insecticide endosulfan (5, 10, and 20?µg?mL^?1) inhibited growth, photosynthetic pigments, photosynthetic, and nitrogenase activities. The sensitivity of N. muscorum to endosulfan was higher than that of N. calcicola. The toxic effect of endosulfan was more pronounced on phycocyanin; however, a considerable reduction in chlorophyll a and carotenoids was also noticed. ¹⁴C-fixation appeared to be more sensitive to the insecticide than photosynthetic oxygen evolution. Endosulfan caused strong inhibition of photosystem (PS) II activity whereas PS I was least affected. The inhibition of PS II activity was partially restored by electron donors (DPC, NH₂OH, and MnCl₂) at low dose of endosulfan. Nitrogenase activity was significantly suppressed in both species by the endosulfan at high dose (20?µg?mL^?1). On the basis of our comparative analysis, N. calcicola was found to be endosulfan resistant and can be used in paddy fields for better productivity under pesticide stress.     

Formation of resistance in the Chironomus plumosus to four pesticides over 45 generations

A study was conducted on the Chironomus plumosus larvae to determine initiation of resistance to four pesticides – chlorfenvinphos, chlorpyrifos, chlorpyrifos-methyl, and malathion. First generational LC₅₀ values were well within the threshold value for chironomids based upon the literature. Subsequent LC₅₀ values were observed to increase, indicating a lessening of the toxicity of the pesticides to the chironomid. In the case of chlorfenvinphos, the 96 h LC₅₀ for generations 1–23 was 6 µg L^?1, in generations 3–7 was 8.57 µg L^?1 and 11.14 µg L^?1 for generations 8–9. Generations 10–12 had an LC₅₀ value of 22.58 µg L^?1 and generation 13 had an LC₅₀ value of 35.08 µg L^?1. Generation 14 had an LC₅₀ value of 47.58 µg L^?1. Generations 15–19 and 20–24 had 96 h LC₅₀ values of 60.68 µg L^?1, 72.58 µg L^?1, 85.08 µg L^?1, 97.58 µg L^?1 and 110.08 µg L^?1, respectively. Generations 25, 26 to 30, 31 to 38 and 39 to 45 had 96 h LC₅₀ values of 160.42 µg L^?1, 210.7 µg L^?1, 262.24 µg L^?1 and 274.36 µg L^?1, respectively. The variation between LC₅₀ values was found to be statistically significant. This was observed for most pesticides tested. Larval size and life cycle duration was observed to change from generation to generation with the body size decreasing markedly from 1 to 0.3 cm with life cycle increasing from 7 to 39 days.     

Producing Cu-loaded algae for feeding experiments: effects of copper on Parachlorella kessleri

Microalgae require several essential metals for optimum growth, which at elevated concentrations may interfere with biochemical and physiological processes, one of them being copper (Cu). The aim of this study is to raise Cu-loaded Parachlorella kessleri as feed for mussels. In order to spike the algae with Cu without lowering their nutritional quality, it is important to know the highest Cu-concentration at which the main parameters remain unaffected, especially in respect to proteins and polysaccharides. The dependence of growth rate, biomass, chlorophyll-a and -b, pheophytin-a, protein, and polysaccharide contents on Cu concentrations are determined. The tests show that P. kessleri is largely unchanged in its nutritional value when exposed to Cu at levels of up to 6?µmol?L^?1. Above 10?µmol?L^?1, toxic effects become obvious, with chlorophyll contents and growth rate being the most sensitive indicators.     

Arsenic in freshwater ecosystems of the Bengal delta: status,sources and seasonal variability

The study aimed to examine the contamination status of arsenic (As) in excavated small water bodies, commonly known as ponds – the integral part of daily life in the arsenic-affected rural areas of West Bengal, India in comparison to the unaffected areas. The ponds of the contaminated area had higher levels of As: water 2–174 µg L^?1 (mean 31 ± 2 µg L^?1) and sediment 1.3–37.3 mg kg^?1 (mean 10.3 ± 0.4 mg kg^?1), than those from the unaffected area: water 1–8 µg L^?1 (mean 4 ± 0 µg L^?1) and sediment 1.4–5.3 mg kg^?1 (mean 3.0 ± 0.1 mg kg^?1). A moderate positive correlation was observed between the water and sediment arsenic content of the ponds of the arsenic-affected region (r = 0.688, n = 277, p < 0.0001). Contaminated ground water, either as direct input or through agricultural washings, was found to be the major contributor of arsenic pollution to these ecosystems. Seasonal variations were not prominent. This study emphasized the beneficial role of using the studied ecosystems over the highly contaminated ground water for various livelihood activities in the Gangetic delta region.     

Green chemistry approach to analysis of formic acid and acetic acid in aquatic environment by headspace water-based liquid-phase microextraction and high-performance liquid chromatography

A simple and totally organic-free (green) method, viz. headspace water-based liquid-phase microextraction combined with high-performance liquid chromatography-ultraviolet detection has been successfully developed for analysis of formic acid and acetic acid in environmental water samples. A microdrop of an aqueous solution of sodium hydroxide was suspended from the tip of a microsyringe needle over the headspace of the stirred sample solution containing the analytes at pH 1.0 for a given time. The microdrop was then retracted into the microsyringe, diluted with HPLC mobile phase, and injected to HPLC. Optimum efficiency has been achieved for: 3.0 µL NaOH microdrop (0.1 mol L^?1) exposed for 15 min over the headspace of an aqueous sample of 6.5 mL at 55 °C, containing 15% w/v of Na₂SO₄, adjusted to pH = 1.0 and stirred at 750 rpm. Under these conditions, enrichment factors of 162 and 187, limits of detection of 0.3 and 0.1 µg L^?1 (S/N = 3) with dynamic linear ranges of 1–500 and 0.5–500 µg L^?1 were obtained for formic acid and acetic acid, respectively. A reasonable repeatability (5.8% ≤ RSD ≤ 8.8%, n = 6) and satisfactory linearity (r² ≥ 0.997) illustrated the performance of the method.     

Prevalence of organochlorine pesticide residues in groundwaters of Kasargod District,India

The Kasargod District is the northernmost district of Kerala State and is bound between the north latitudes 12°02′27″ and 12°47′35″ and east longitudes 74°51′54″ and 75°25′25″. The present study highlights the contamination levels of organochlorine pesticides in open wells of the Kasargod District from 2010 to 2011. Maximum contamination of organochlorine pesticides (OCP's) was observed for endosulfan followed by hexachlorobenzene (BHC). Contamination levels of α-endosulfan were higher at Panathur (58?µg?L^?1) and next to Periya (37?µg?L^?1) in the postmonsoon season of 2010. During premonsoon 2011, the residue levels of α-endosulfan were higher at Panathady (56?µg?L^?1) followed by Rajapuram (40?µg?L^?1). Contamination levels of the BHC isomers exhibit the order of γ-BHC?>?α-BHC?>?β‐BHC, showing that γ-BHC represents 62% of the total OCP residues in premonsoon 2010. Among the studied OCP's, concentration levels of DDT were below detection limit. Maximum concentrations of the sum of all OCP residues were observed at Mulleria and Cheemeni (premonsoon 2010), followed by Panathur and Periya (postmonsoon 2010), and lowest in Panathady and Rajapuram (premonsoon 2011). Residues of OCP's were lowest in Paettikundu and Cheravatur in all the three seasons.     

Deltamethrin-induced alterations in serum calcium and prolactin cells of a freshwater teleost,Heteropneustes fossilis

Deltamethrin, a pyrethroid insecticide widely used in many countries, causes significant adverse effects in aquatic ecosystems. The concentration of deltamethrin in water reservoirs and the run off from agricultural areas (in water) in many countries range up to 24.0?µg?L^?1 which is higher than the recommendation of the European Union standard. Hence, in this study the effects of deltamethrin were investigated, i.e. its toxic impacts on the freshwater catfish Heteropneustes fossilis in terms of serum calcium and prolactin cells (located in the rostral pars distalis region of the pituitary). The fish were subjected to deltamethrin for a short-term experiment (96?h; 1.5?µg?L^?1 e.0.8 of 96?h LC₅₀) and a long-term experiment (28 days; 0.37?µg?L^?1 e.0.2 of 96?h LC₅₀). After short-term deltamethrin exposure, serum calcium levels decrease. No histological change in prolactin cells is noticed throughout the short-term experiment. Fish exposed to deltamethrin for 7 days also exhibit a decrease in serum calcium level. This decrease persisted until the end of the experiment (28 days). Prolactin cells of fish treated for 14 days with deltamethrin exhibit increased nuclear volume and degranulation, increasing progressively from the 21st day onwards. After 28 days, a few degenerated cells are discerned. The results of this study show that deltamethrin is moderately toxic for the freshwater fish H. fossilis by producing adverse effects on serum calcium and prolactin cells. Hence, it should be used with caution in areas near fish-inhabited waters.     

Immunotoxic effect of arsenic trioxide on Caenorhabditis elegans

A Pseudomonas aeruginosa–Caenorhabditis elegans pathogenesis model was utilized to assess immunotoxic effects of arsenic trioxide (As₂O₃). After 2 h of As₂O₃ exposure, 500 µmol L^?1 and 1 mmol L^?1 As₂O₃ treatment significantly decreased median survivals of C. elegans (10 h after L4/adult molt). However, 2 h of As₂O₃ exposure caused no significant changes in the survivals rates of C. elegans (2 h after L4/adult molt). Notably, a significant dose-related immunoenhancement was observed in C. elegans (2 h after L4/adult molt) after 12 h of arsenite exposure.     

Alteration of photosystem II activity by atrazine on Chlamydomonas reinhardtii synchronized and asynchronized cell cycle cultures

Inhibition of photosystem II (PSII) activity by atrazine was investigated in the green alga Chlamydomonas reinhardtii during different states of the cell cycle. The algal cultures were maintained under continuous light or under light/dark cycle (16/8?h) to obtain homogenized cell cycle distribution. The cycle state of algal population was determined by the DNA content using flow cytometry and defined as newly divided cells before the initiation of DNA replication (G₀/G₁) and cells at the end of the replication cycle with fully duplicated DNA content (G₂/M). Under different synchronized states of the cell population, the photosynthetic activity was investigated after treatment at 10, 100, and 1000?µmol?L^?1 atrazine exposed for 24?h by using fluorescence parameters related to PSII activity measured with a plant efficiency analyzer and pulse-amplitude modulated methods. In this study, we found that the atrazine effect was different depending on cell cycle phases and the period of illumination. Algal cells under light–dark cycle showed inhibition of the PSII electron transport leading to an increase of heat energy dissipation by the PSII reaction center. Algal cells grown under continuous light was shown to be more resistant to atrazine than the cells grown under light–dark cycle.     

Determination of glyoxal and methylglyoxal in atmospheric particulate matter by 2,4-dinitrophenylhydrazine derivatisation

A simple and rapid method has been optimised to determine glyoxal and methylglyoxal in atmospheric particulate matter by extraction and derivatisation with 2,4-dinitrophenylhydrazine solutions. Minimal sample preparation was required by mixing a portion of filter charged with atmospheric particulate matter with 5?mL of a saturated solution of 2,4-dinitrophenylhydrazine (1.6?g?L^?1) in acetonitrile and acidified by H₂SO₄ (50?µL?L^?1). Chromatographic analyses were carried out 1?h after derivatisation solution was mixed. Finally, the proposed method was applied to quantify these dicarbonyls in atmospheric particulate matter samples, which were obtained as part of a large field study to characterise atmospheric aerosol from a rural area of Madrid. Glyoxal concentrations averaged 0.24?ng?m^?3, whereas mean values of methyl glyoxal were around 0.95?ng?m^?3. Methyl glyoxal levels showed a clear relationship with the particulate matter levels, whereas glyoxal data did not show such a correlation. This could indicate that both dicarbonyls come from different sources.     

Efficiency of Zn phytoextraction,biomass yield and formation of low-molecular-weight organic acids in S × rubens – a hydroponic experiment

The aim of the study was to estimate Zn phytoextraction and changes in biomass of S?×?rubens growing in modified Knop's solution with different levels of Zn addition (0.5, 1.0, 2.5 and 5.0?mM). Obtained results were correlated with secretion of selected low-molecular-weight organic acids (LMWOAs) in the rhizosphere, roots and leaves. An increase in Zn concentration in Knop's solution resulted in Zn accumulation in roots, shoots and leaves. The highest accumulation was observed for plants growing in 5?mM Zn, at concentration levels 4741.36?±?98.66, 1227.31?±?16.57 and 2241.65?±?34.90?mg?kg^?1 DW in roots, shoots and leaves, respectively. The bioaccumulation factor and the translocation factor for plants growing in 0.5, 1.0 and 2.5?mM Zn clearly indicate that this Salix taxon is an effective Zn accumulator. The general reduction of Salix biomass with an increase in Zn concentration in the solution was observed. In the rhizosphere, the total LMWOA concentration was almost 0.93?µmol?kg^?1 DM for control (Zn free) plants, while for 5.0?mM of Zn it was 4.9?µmol?kg^?1 DM. Increasing concentrations of acids were observed in roots (1.34 for the control and 5.57?µmol?kg^?1 DM for plants treated with 2.5?mM of Zn).