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Methyl parathion and its degradation product p-nitrophenol have become important environmental problems due to their high toxicity and persistence. In this study, the toxicological mechanism of methyl parathion and p-nitrophenol exposure increasing the risk of depression was studied through network toxicology and molecular docking methods. Based on the comprehensive analysis of PharmMapper, STITCH, SwissTargetPrediction, Similarity ensemble approach (SEA) and GeneCards databases, 35 potential targets related to methyl parathion and p-nitrophenol exposure were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed the key pathways of methyl parathion and p-nitrophenol affecting depression, included insulin-like growth factor receptor signaling pathway, serotonergic synapse. Combined with protein-protein interaction (PPI) network analysis and KEGG analysis, 14 core targets of depression related to methyl parathion and p-nitrophenol were screened out. Further, the targets MAP2K1 and APP with the highest binding scores with methyl parathion and p-nitrophenol, respectively, were screened by DeepPurpose, and the common target HRAS for molecular docking was determined. The molecular docking analysis further verified that methyl parathion and p-nitrophenol may have good binding activity with HRAS. This study provides valuable insights for understanding the molecular mechanism of environmental pollutants methyl parathion and p-nitrophenol affecting depression, and provides a theoretical basis for understanding the health risks of methyl parathion and p-nitrophenol.

Characterizing the adaptive landscapes that encompass the emergence of novel enzyme functions can provide molecular insights into both enzymatic and evolutionary mechanisms. Here, we combine ancestral protein reconstruction with biochemical, structural and mutational analyses to characterize the functional evolution of methyl-parathion hydrolase (MPH), an organophosphate-degrading enzyme. We identify five mutations that are necessary and sufficient for the evolution of MPH from an ancestral dihydrocoumarin hydrolase. In-depth analyses of the adaptive landscapes encompassing this evolutionary transition revealed that the mutations form a complex interaction network, defined in part by higher-order epistasis, that constrained the adaptive pathways available. By also characterizing the adaptive landscapes in terms of their functional activities towards three additional organophosphate substrates, we reveal that subtle differences in the polarity of the substrate substituents drastically alter the network of epistatic interactions. Our work suggests that the mutations function collectively to enable substrate recognition via subtle structural repositioning. Ancestral protein reconstruction followed by biochemical and structural analyses characterizes the evolutionary trajectory of methyl-parathion hydrolase from an ancestral dihydrocoumarin hydrolase through the accumulation of five key mutations.

Methyl parathion (MP), an organophosphorus insecticide, is commonly used in agricultural products for food preservation and pest control. Due to the severe threat it poses to food safety and the environment, monitoring MP residues has attracted much attention. Traditional spectroscopic and chromatographic methods have been used successfully to analyze MP in a wide range of samples; however, these approaches have several drawbacks, such as requiring specialized equipment, trained technicians, and extensive sample preparation time. Due to these restrictions, there is a growing demand for analysis methods that can reliably and quickly detect MP at trace quantities while also being quick, sensitive, and selective. Electrochemical sensors have emerged over the past few decades as a viable alternative to more time-consuming and laborious analysis methods for detecting MP. However, the performance of electrochemical sensors has been dramatically improved thanks to recent breakthroughs in nanoscience. This study offers an overview of the creation and operation of carbon nanomaterial-based electrochemical sensors (including carbon nanotubes (CNTs), graphene (Gr), and other carbon nanomaterials) to identify MP residues in waters, fruits, and vegetables. A brief discussion of the potential benefits, drawbacks, and future research prospects of MP electrochemical sensors based on carbon nanomaterials is also offered.

Pesticides play a significant role in crop production and have become an inevitable part of the modern environment due to their extensive distribution throughout the soil ecosystem. Prophylactic applications of chlorpyrifos (CP) affect soil fertility, modify soil microbial community structure, and pose potential health risks to the nontarget organisms. Bioremediation through microbial metabolism is found to be an ecofriendly and cheaper process for CP removal from the environment. So far, various bacterial and fungal communities have been reported for CP and its metabolites degradation. Organophosphorus hydrolase (OPH) and methyl parathion hydrolase (MPH) are crucial bacterial enzymes for CP degradation as they efficiently hydrolyze the unbreakable P-O and P = S bond. This review discusses the prospects of toxicity level, persistency, and harmful effects of CP on the environment. CP degradation mechanisms, metabolic pathways, and key enzymes, along with their structural details, are also featured. The highlights on molecular docking with OPH and MPH enzyme for CP show the best binding affinity with OPH; hence, it is an essential part of CP degradation. Simultaneously, metagenomic analysis of soil from contaminated agricultural lands and wastewater was analyzed with the goal to identify the dominant CP degraders and enzymes. The identification of potent degraders, key enzymes, and evaluation of microbial community dynamics upon pesticide exposure can be used as a warning for its dissemination and biomagnification into the food chain.

Methyl parathion (MP), as a typical organophosphorus pesticide, has been widely used in pest control and plant growth regulation. Simultaneously, the problem of pesticide residues also poses a serious threat to the environment and human health. Currently, pesticide residue detection technology still faces great challenges in practical applications due to the problems of expensive facilities and complicated operations in conventional analysis methods. To address these problems, a novel nonenzymatic electrochemical pesticide sensor was reported. A zirconium-based metal organic framework material with terephthalic acid as a ligand (Zr-BDC) was designed to combine with electro-reduced graphene oxides (rGO). The Zr-BDC-rGO nanocomposite contains Zr-OH groups with high affinity for phosphate groups, endowing it with selective recognition and a higher adsorption capacity for MP. Moreover, rGO has a high specific surface area and excellent electron transport capability, making it an excellent functionalized adsorption and substrate material, which could improve the conductivity of the material and achieve a lower detection limit. Upon optimization, this sensor provided a wide linear range from 0.001 to 3.0 μg mL−1 and low limit of detection 0.5 ng mL−1 for MP. This work provides a rapid, sensitive and cost-effective sensing platform for pesticide residue detection.

We developed a highly sensitive and selective method for double-signal analysis (fluorescence and ultraviolet–visible spectrophotometry) of organophosphorus pesticides (OPs), based on reversible quenching of graphene quantum dots (GQDs; fluorophores) with silver nanoparticles (AgNPs; absorbers). We used acetylcholinesterase to catalytically convert acetylthiocholine into thiocholine. In turn, by competitive binding to the AgNPs, the produced thiocholine displaces AgNPs from the GQDs and thus induces fluorescence recovery. However, OP analytes inhibit the activity of acetylcholinesterase and, in so doing, retain the silver–graphene nanoparticle complex and fluorescence quenching. The degree of quenching is proportional to the concentration of OPs; the detection limit is as low as 0.017 μg/L. The ultraviolet–visible absorption of GQDs/AgNPs at 390 nm decreases—because of AgNP aggregation that occurs after desorption from the GQDs—and the absorbance is linearly proportional to the OP concentration. Our system has good selectivity to substances that are commonly present in water and vegetables. We successfully applied our method to OP analysis in water, apple, and carrot samples.

Pesticides are used for controlling the development of various pests in agricultural crops worldwide. Despite their agricultural benefits, pesticides are often considered a serious threat to the environment because of their persistent nature and the anomalies they create. Hence removal of such pesticides from the environment is a topic of interest for the researchers nowadays. During the recent years, use of biological resources to degrade or remove pesticides has emerged as a powerful tool for their in situ degradation and remediation. Fungi are among such bioresources that have been widely characterized and applied for biodegradation and bioremediation of pesticides. This review article presents the perspectives of using fungi for biodegradation and bioremediation of pesticides in liquid and soil media. This review clearly indicates that fungal isolates are an effective bioresource to degrade different pesticides including lindane, methamidophos, endosulfan, chlorpyrifos, atrazine, cypermethrin, dieldrin, methyl parathion, heptachlor, etc. However, rate of fungal degradation of pesticides depends on soil moisture content, nutrient availability, pH, temperature, oxygen level, etc. Fungal strains were found to harbor different processes including hydroxylation, demethylation, dechlorination, dioxygenation, esterification, dehydrochlorination, oxidation, etc during the biodegradation of different pesticides having varying functional groups. Moreover, the biodegradation of different pesticides was found to be mediated by involvement of different enzymes including laccase, hydrolase, peroxidase, esterase, dehydrogenase, manganese peroxidase, lignin peroxidase, etc. The recent advances in understanding the fungal biodegradation of pesticides focusing on the processes, pathways, genes/enzymes and factors affecting the biodegradation have also been presented in this review article.

The current approach for the risk assessment of chemicals does not account for the complex human real-life exposure scenarios. Exposure to chemical mixtures in everyday life has raised scientific, regulatory, and societal concerns in recent years. Several studies aiming to identify the safety limits of chemical mixtures determined hazardous levels lower than those of separate chemicals. Following these observations, this study built on the standards set by the real-life risk simulation (RLRS) scenario and investigated the effect of long-term exposure (18 months) to a mixture of 13 chemicals (methomyl, triadimefon, dimethoate, glyphosate, carbaryl, methyl parathion, aspartame, sodium benzoate, EDTA, ethylparaben, butylparaben, bisphenol A and acacia gum) in adult rats. Animals were divided into four dosing groups [0xNOAEL (control), 0.0025xNOAEL (low dose—LD), 0.01xNOAEL (medium dose—MD) and 0.05xNOAEL (high dose-HD) (mg/kg BW/day)]. After 18 months of exposure, all animals were sacrificed, and their organs were harvested, weighed, and pathologically examined. While organ weight tended to be higher in males than in females, when sex and dose were taken into account, lungs and hearts from female rats had significantly greater weight than that of males. This discrepancy was more obvious in the LD group. Histopathology showed that long-term exposure to the chemical mixture selected for this study caused dose-dependent changes in all examined organs. The main organs that contribute to chemical biotransformation and clearance (liver, kidneys, and lungs) consistently presented histopathological changes following exposure to the chemical mixture. In conclusion, exposure to very low doses (below the NOAEL) of the tested mixture for 18 months induced histopathological lesions and cytotoxic effects in a dose and tissue-dependent manner.

In this study, nanostructured gold was successfully prepared on a bare Au electrode using the electrochemical deposition method. Nanostructured gold provided more exposed active sites to facilitate the ion and electron transfer during the electrocatalytic reaction of organophosphorus pesticide (methyl parathion). The morphological and structural characterization of nanostructured gold was conducted using field-emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), which was further carried out to evaluate the electrocatalytic activity towards methyl parathion sensing. The electrochemical performance of nanostructured gold was investigated by electrochemical measurements (cyclic voltammetry (CV) and differential pulse voltammetry (DPV)). The proposed nanostructured gold-modified electrode exhibited prominent electrochemical methyl parathion sensing performance (including two linear concentration ranges from 0.01 to 0.5 ppm (R2 = 0.993) and from 0.5 to 4 ppm (R2 = 0.996), limit of detection of 5.9 ppb, excellent selectivity and stability), and excellent capability in determination of pesticide residue in real fruit and vegetable samples (bok choy and strawberry). The study demonstrated that the presented approach to fabricate a nanostructured gold-modified electrode could be practically applied to detect pesticide residue in agricultural products via integrating the electrochemical and gas chromatography coupled with mass spectrometry (GC/MS-MS) analysis.

Metal–organic framework (UiO-66) derived nanoporous carbon/electrochemically reduced graphene oxide nanocomposite (UiO-66/NPC/ERGO) was developed to fabricate an electrochemical sensor for achieving efficient detection of methyl parathion (MP) residues in food. The carbonization derivative UiO-66/NPC was synthesized by one-step pyrolysis with only UiO-66 precursor. Based on the synergistic effect of enough active absorption sites and specific absorption of UiO-66/NPC for MP as well as the high conductivity of ERGO, the UiO-66/NPC/ERGO sensor exhibited excellent sensing performance. Under the optimal conditions, a linear determination range of 20–4000 ng/mL and low limit of detection (LOD) of 0.395 ng/mL for MP was obtained by direct electrochemical oxidation using SWV. Additionally, the sensor provided excellent stability and selectivity, as well as effective determination of real samples with satisfactory recoveries (98.5–104.0%), manifesting that the UiO-66/NPC/ERGO has great potential for organophosphorus pesticide detection. Graphical Abstract