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Biomarkers for the assessment of chlorpyrifos effects on earthworms and on soil functional parameters
Piola, Lucas;Fuchs, Julio;Oneto, María Luisa;Basack, Silvana;Giménez, Rosana;Massaro, Rubén;Papa, Juan Carlos;Kesten, Eva;Casabé, Norma;
Pesquisa Agropecuária Brasileira , 2009, DOI: 10.1590/S0100-204X2009000800011
Abstract: the objective of this work was to evaluate the effects of chlorpyrifos on earthworms and on soil functional parameters. an integrated laboratory-field study was performed in a wheat field in argentina, sprayed with chlorpyrifos at two recommended application rates (240 or 960 g ha-1 style='vertical-align:baseline'> a.i.). laboratory tests included neutral red retention time, comet assay (single cell gel electrophoresis), and avoidance behavior, each using the earthworm eisenia andrei exposed in soil collected 1 or 14 days after pesticide application, and the bait-lamina test. field tests assessed organic matter breakdown using the litterbag and bait-lamina assays. earthworm populations in the field were assessed using formalin application and hand-sorting. the neutral red retention time and comet assays were sensitive biomarkers to the effects of chlorpyrifos on the earthworm e. andrei; however, the earthworm avoidance test was not sufficiently robust to assess these effects. feeding activity of soil biota, assessed by the bait lamina test, was significantly inhibited by chlorpyrifos after 97 days, but recovered by the 118th day of the test. litterbag test showed no significant differences in comparison to controls. earthworm abundance in the field was too low to adequately test the sensitivity of this assessment endpoint.
Bioavailability of Chlorpyrifos in Wheat Plants (Triticum aestivun)  [PDF]
Sylvia V. Copaja, Rosa Vergara, Héctor R. Bravo
Agricultural Sciences (AS) , 2014, DOI: 10.4236/as.2014.58069
Abstract:

Adsorption processes of chlorpyrifos in two Chilean agro soils (Calera: C; San Esteban: SE) in relation with the bioaccumulation in wheat plants (Triticum aestivun) were studied. RP-HPLC method was developed to determine the chlorpyrifos content in soils, roots and seedling tissues. The two soils showed high adsorption capacity (C = 78%, SE = 92%). The values are not in relation with the contents of organic matter (C = 3.9% and SE = 2.0%) and clay (C = 12.7% and SE = 10.1%) determined in the soils. Persistence and mobility of chlorpyrifos in the soils were estimated from halflife values (Csoil = 23 d, SEsoil = 14 d) and the Guss index (Csoil = 0.89, SEsoil = 0.25) respectively. These values are in the range of non-leaching compounds, and suggest that there should be no pollutant in the ground water. Wheat plants grown in both soils incubated with chlorpyrifos bioaccumulate residues in roots and seedling tissues. Root tissues showed the greatest contents (C = 22.3 mg/k. f. wt; SE = 51.8 mg/kg. f. wt.). Germination and growth of wheat young plants were not inhibited for the contents in the tissues. A relation between the levels of chlorpyrifos residues in the soils and the bioaccumulation in wheat tissues was estimated from the BAI parameter. Values showed that the bioaccumulation is dependent on the residues contents in soils. These results suggest that bioavailability of chlorpyrifos in wheat plants may be a harmful pollutant for mammals if it remains stable at all growth stage of the plant. Further research should be considered to see if bioavailability in forage and/or grain can occur.

Computational approaches for Oral bioavailability prediction: An overview  [PDF]
Rajnish Kumar*,Anju Sharma,Pritish Kumar Varadwaj
Biomirror , 2010,
Abstract: High oral bioavailability is among the most important consideration during drug development process. Oral-bioavailability is usually determined in the pre-clinical stage of drug development process. It was found that 30% of drugs fail during the drug discovery process. Therefore there is a need of a robust and accurate computational model which can predict the oral bioavailability of compounds without carrying out any experiments. There exists a plethora of studies to predict oral bioavailability which indicates that it is incredibly rich area of research. Various attempts in estimating oral bioavailability are reported in literature belonging to different categories. In this article computational oral bioavailability prediction approaches are discussed.
Determination of Pirimiphos-Methyl and Chlorpyrifos-Ethyl Residues on Tomato and Pepper Fruits Grown in Greenhouse  [PDF]
Mohammed A. Al-Eed
Journal of Applied Sciences , 2006,
Abstract: The objective of this reserch is to determine the residues of pirimiphos-methyl and Chlorpyrifos-ethyl insecticides on greenhouse tomato and pepper fruits, a green house trial was carried out at the King Faisal Research Station, King Faisal University, Al-Hassa, Saudi Arabia. The experiment was designed in randomize block design. Samples of tomato and pepper fruits were randomly collected from treated and non-treated plants after a time elapse of one hour, , and 7 days post insecticide treatments. Fruit extracts were analyzed for pirimiphos-methyl and Chlorpyrifos-ethyl residues using gas chromatography. The data showed that pirimiphos-methyl was vastly degraded when compared with Chlorpyrifos-ethyl. Chlorpyrifos-ethyl degradation of 8.2, .2 and 73.2% were recorded as compared with 30.4, 89.5 and 94.8% for pirimiphos-methyl after one, three and seven days, respectively. Chlorpyrifos-ethyl residues on tomato or pepper fruits after 3 days, represented more than ten folds of the maximum residue limits on vegetables (50 μg kg-1). The data also showed that the rates of degradation were 0.14 and 0.44 day-1 and 0.28 and 0.18 day-1 and the t1/2 was 4.8 and 1.6 day for pirimiphos-methy l and .5 and .9 day for chlorpyrifos-ethyl on tomato and pepper, respectively.
Quantitative Determination of Chlorpyrifos and Penconazole Residues in Grapes Using Gas Chromatography/Mass Spectrometry
Yacoub Batta,Nidal Zatar,Safa Sama`neh
Journal of Food Technology , 2013,
Abstract: Samples of grape leaves and berries (CV: Zeini) were taken from grape-vine yards treated with chlorpyrifos (Dursban?) and penconazole (Ofir?) in order to determine their residues in these organs. The effect of time after spraying and number of sprays on the residues of both pesticides was studied. Gas chromatorgraphy /mass spectrometry (GC/MS) was used to determine the residue levels. Results obtained have indicated the presence of both pesticides in the tested leaf samples, but chlorpyrifos residues were detected in larger quantities than penconazole residues. Also, larger quantities of both pesticides were detected in the samples of berry cortex than in the samples of berry flesh. However, the residues of both pesticides in washing water of treated berries were lower than that in the cortex or in the flesh. This may indicate the systemic action of esticides especially penconazole, since washing the treated berries with water two weeks after application of the last spray did not remove the pesticides from berries. Overall results have indicated that the determined quantities of both pesticides residues especially in the cortical tissues of treated berries following the sixth application of both pesticides were higher than the quantities reported by other authors in grape berries, but they were generally less than the maximum residue limits (MRLS) defined by the residue legislations in other countries.
Earthworms and Plant Residues Modify Nematodes in Tropical Cropping Soils (Madagascar): A Mesocosm Experiment  [PDF]
Cécile Villenave,Bodo Rabary,Emilie Kichenin,Djibril Djigal,Eric Blanchart
Applied and Environmental Soil Science , 2010, DOI: 10.1155/2010/323640
Abstract: Free-living nematodes present several characteristics that have led to their use as bioindicators of soil quality. Analyzing the structure of nematofauna is a pertinent way to understand soil biological processes. Earthworms play an important role in soil biological functioning and organic matter dynamics. Their effects on soil nematofauna have seldom been studied. We studied the effect of the tropical endogeic earthworm, Pontoscolex corethrurus, on nematode community structure in a 5-month field mesocosm experiment conducted in Madagascar. Ten different treatments with or without earthworms and with or without organic residues (rice, soybean) were compared. Organic residues were applied on the soil surface or mixed with the soil. The abundance of nematodes (bacterial and fungal feeders) was higher in presence of P. corethrurus than in their absence. The type of plant residues as well as their localisation had significant effects on the abundance and composition of soil nematodes. The analysis of nematode community structure showed that earthworm activity led to an overall activation of the microbial compartment without specific stimulation of the bacterial or fungal compartment. 1. Introduction Soil organisms play a leading role in decomposition and mineralization of organic matter (OM) [1]. They are involved in processes that affect carbon (C) sequestration as well as in the modification of soil physical structure and chemical properties. They also interact with other soil fauna and these interactions result in complex food webs [2]. Nematodes are small organisms (ca. 1?mm long at the adult stage) abundant in soil (several million m ? 2 soil), they present a high species diversity (about 11,000 species have already been described). Nematodes live in the film of water between soil particles and present various feeding behaviours. During the last twenty years, many studies have been conducted on these microfaunal organisms because they can be an efficient tool to assess soil quality and soil biological functioning [2–4]. Because they are present at different levels of the soil food web and present variable tolerance toward stress, nematofauna provide information about OM decomposition pathways and soil pollution status [3, 5–7]. Nematodes interact with other soil organisms including earthworms, which also play an important role in soil biological functioning and OM dynamics [8, 9]. Until now, studies on interactions between nematodes and earthworms have focused on the contribution of earthworm burrowing and casting activity to nematofauna abundance,
Efectos tóxicos de los insecticidas clorpirifos y teflutrina sobre la lombriz de tierra (Lumbricus terrestris L.) Toxic effects of the insecticides chlorpyrifos and tefluthrin on earthworms (Lumbricus terrestris L.)  [cached]
Rosana Giménez,Angela Della Penna,Ezequiel Odello
Agricultura Técnica , 2004,
Abstract: Para evaluar la ecotoxicidad de clorpirifos y teflutrina sobre Lumbricus terrestris L., se realizó una prueba de laboratorio, basado en el protocolo de la Organización Internacional de Control Biológico (IOBC). Las lombrices fueron recolectadas a mano en un suelo libre de plaguicidas, en el campo de la Facultad de Agronomía, Universidad de Buenos Aires, Argentina y colocadas en suelo esterilizado, en condiciones de oscuridad y 12°C durante cinco días, alimentadas con hojas secas de trébol blanco (Trifolium repens L.). Se colocó una lombriz mayor a 1,5 g sin clitelo por embudo de Daniel, con diez hojas secas de trébol blanco sobre la superficie. Los tratamientos fueron: 1) testigo, agua no clorada; 2) 30 mg L-1 de solución de cloroacetamida (97,37%); 3) clorpirifos (EC 48%) 5 L ha-1 o 50 mg L-1; 4) teflutrina (EC 5%) 2 L ha-1 o 20 mg L-1. El ensayo tuvo dise o completamente aleatorizado con diez repeticiones. Durante los 15 días de ensayo las variables analizadas fueron: variación de peso, actividad individual y supervivencia de lombrices. El incremento de peso de las lombrices fue 0,285; 0,280 y 0,300 g en 15 días en los tratamientos 1, 3 y 4 respectivamente, y no hubo diferencias significativas entre los mismos así como en la cantidad de hojas retiradas al día, que fue de 0,61; 0,369; 0,555 y 0,425, respectivamente. La supervivencia fue de 100; 20; 100; y 90% en los tratamientos 1, 2, 3 y 4, respectivamente, siendo afectada sólo por cloroacetamida. Clorpirifos y teflutrina no fueron tóxicos a las dosis evaluadas (P < 0,5). In order to evaluate the ecotoxicity of chlorpyrifos and tefluthrin on the earthworm Lumbricus terrestris L., a laboratory test was carried out based on the guidelines of the International Organization of Biological Control (IOBC). The earthworms were collected by handsorting from a soil free of pesticides of the Agronomy Faculty, University of Buenos Aires, Argentina and placed in sterilized soil, in complete darkness, at 12oC for five days, and fed with dry white clover (Trifolium repens L.) leaves. Earthworms larger than 1.5 g without clitelum were placed in a Daniel's funnel with ten dry leaves of white clover on the surface. The treatments were: 1) control, unchlorinated water; 2) chloroacetamid solution (97.37%) 30 mg L-1; 3) chlorpyrifos (emulsifiable concentrate, EC, 48%) 5 L ha-1 or 50 mg L-1; 4) tefluthrin (EC 5%) 2 L ha-1 or 20 mg L-1. A completely randomized experimental design with ten replicates was used. During 15 days of the assay the variables analyzed were: live weight change, individual activity and earthworm survi
A Novel Chemometric Method for the Prediction of Human Oral Bioavailability  [PDF]
Xue Xu,Wuxia Zhang,Chao Huang,Yan Li,Hua Yu,Yonghua Wang,Jinyou Duan,Yang Ling
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms13066964
Abstract: Orally administered drugs must overcome several barriers before reaching their target site. Such barriers depend largely upon specific membrane transport systems and intracellular drug-metabolizing enzymes. For the first time, the P-glycoprotein (P-gp) and cytochrome P450s, the main line of defense by limiting the oral bioavailability (OB) of drugs, were brought into construction of QSAR modeling for human OB based on 805 structurally diverse drug and drug-like molecules. The linear (multiple linear regression: MLR, and partial least squares regression: PLS) and nonlinear (support-vector machine regression: SVR) methods are used to construct the models with their predictivity verified with five-fold cross-validation and independent external tests. The performance of SVR is slightly better than that of MLR and PLS, as indicated by its determination coefficient ( R 2) of 0.80 and standard error of estimate (SEE) of 0.31 for test sets. For the MLR and PLS, they are relatively weak, showing prediction abilities of 0.60 and 0.64 for the training set with SEE of 0.40 and 0.31, respectively. Our study indicates that the MLR, PLS and SVR-based in silico models have good potential in facilitating the prediction of oral bioavailability and can be applied in future drug design.
Systems Biological Approach of Molecular Descriptors Connectivity: Optimal Descriptors for Oral Bioavailability Prediction  [PDF]
Shiek S. S. J. Ahmed, V. Ramakrishnan
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040654
Abstract: Background Poor oral bioavailability is an important parameter accounting for the failure of the drug candidates. Approximately, 50% of developing drugs fail because of unfavorable oral bioavailability. In silico prediction of oral bioavailability (%F) based on physiochemical properties are highly needed. Although many computational models have been developed to predict oral bioavailability, their accuracy remains low with a significant number of false positives. In this study, we present an oral bioavailability model based on systems biological approach, using a machine learning algorithm coupled with an optimal discriminative set of physiochemical properties. Results The models were developed based on computationally derived 247 physicochemical descriptors from 2279 molecules, among which 969, 605 and 705 molecules were corresponds to oral bioavailability, intestinal absorption (HIA) and caco-2 permeability data set, respectively. The partial least squares discriminate analysis showed 49 descriptors of HIA and 50 descriptors of caco-2 are the major contributing descriptors in classifying into groups. Of these descriptors, 47 descriptors were commonly associated to HIA and caco-2, which suggests to play a vital role in classifying oral bioavailability. To determine the best machine learning algorithm, 21 classifiers were compared using a bioavailability data set of 969 molecules with 47 descriptors. Each molecule in the data set was represented by a set of 47 physiochemical properties with the functional relevance labeled as (+bioavailability/?bioavailability) to indicate good-bioavailability/poor-bioavailabilit?ymolecules. The best-performing algorithm was the logistic algorithm. The correlation based feature selection (CFS) algorithm was implemented, which confirms that these 47 descriptors are the fundamental descriptors for oral bioavailability prediction. Conclusion The logistic algorithm with 47 selected descriptors correctly predicted the oral bioavailability, with a predictive accuracy of more than 71%. Overall, the method captures the fundamental molecular descriptors, that can be used as an entity to facilitate prediction of oral bioavailability.
Dissipation of chlorpyrifos on pakchoi inside and outside greenhouse
YU Yun-long,FANG Hu,WANG Xiao,YU Jing-quan,FAN De-fang,
YU Yun-long
,FANG Hu,WANG Xiao,YU Jing-quan,FAN De-fang

环境科学学报(英文版) , 2005,
Abstract: The dissipation of chlorpyrifos on pakchoi inside and outside greenhouse was studied. The decline curve of chlorpyrifos on pakchoi could be described as first-order kinetic. The experimental data showed that both the hermetic environment of greenhouse and season affected dissipation rates of chlorpyrifos on pakchoi. Chlorpyrifos declined faster outside greenhouse than inside greenhouse. Chlorpyrifos residues at pre-harvest time were below the maximum residue limits(MRLs) fixed in China, whereas the values inside greenhouse were higher than those outside greenhouse by almost 50%. The recommended pre-harvest time established under conditions of open field might not always fit to greenhouse production.
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