Phytoremediation of cadmium-trichlorfon co-contaminated water by Indian mustard (Brassica juncea): growth and physiological responses.

In this study, the morphological and physiological responses of Brassica juncea to the stresses of Cadmium (Cd) and trichlorfon (TCF), and the phytoremediation potential of B. juncea to Cd and TCF were investigated under hydroponics. Results showed that Cd exhibited strong inhibition on biomass and root morphology of B. juncea as Cd concentration increased. The chlorophyll a fluorescence intensity and chlorophyll content of B. juncea decreased with the increased Cd concentration, whereas the malondialdehyde and soluble protein contents and superoxide dismutase activity increased. TCF with different concentrations showed no significant influence on these morphological and physiological features of B. juncea. The biomass and physiological status of B. juncea were predominantly regulated by Cd level under the co-exposure of Cd and TCF. B. juncea could accumulate Cd in different plant parts, as well as showed efficient TCF degradation performance. A mutual inhibitory removal of Cd and TCF was observed under their co-system. The present study clearly signified the physiological responses and phytoremediation potential of B. juncea toward Cd and TCF, and these results suggest that B. juncea can be used as an effective phytoremediation agent for the Cd-TCF co-contamination in water.

Combined pollution of heavy metals and pesticides in agricultural water systems is a common phenomenon. In previous phytoremediation studies, limited information is available on the co-contamination of heavy metals and pesticides. In this study, we aimed to investigate the concentration-dependent morphological and physiological characteristics of B. juncea under single and co-stress of Cd and trichlorfon (TCF), and the phytoremediation ability of B. juncea to remove Cd and TCF through hydroponic experiment. B. juncea exhibited efficient removal performance of Cd and TCF alone and simultaneous exposure of both pollutants, indicating that B. juncea is an effective phytoremediation agent for the Cd-TCF co-contaminated water.

Developmental Neurotoxicity of Trichlorfon in Zebrafish Larvae.

Trichlorfon is an organophosphorus pesticide widely used in aquaculture and has potential neurotoxicity, but the underlying mechanism remains unclear. In the present study, zebrafish embryos were exposed to trichlorfon at concentrations (0, 0.1, 2 and 5 mg/L) used in aquaculture from 2 to 144 h post fertilization. Trichlorfon exposure reduced the survival rate, hatching rate, heartbeat and body length and increased the malformation rate of zebrafish larvae. The locomotor activity of larvae was significantly reduced. The results of molecular docking revealed that trichlorfon could bind to acetylcholinesterase (AChE). Furthermore, trichlorfon significantly inhibited AChE activity, accompanied by decreased acetylcholine, dopamine and serotonin content in larvae. The transcription patterns of genes related to acetylcholine (e.g., ache, chrna7, chata, hact and vacht), dopamine (e.g., drd4a and drd4b) and serotonin systems (e.g., tph1, tph2, tphr, serta, sertb, htrlaa and htrlab) were consistent with the changes in acetylcholine, dopamine, serotonin content and AChE activity. The genes related to the central nervous system (CNS) (e.g., a1-tubulin, mbp, syn2a, shha and gap-43) were downregulated. Our results indicate that the developmental neurotoxicity of trichlorfon might be attributed to disorders of cholinergic, dopaminergic and serotonergic signaling and the development of the CNS.

The Combined Use of Copper Sulfate and Trichlorfon Exerts Stronger Toxicity on the Liver of Zebrafish.

In aquaculture, copper sulphate and trichlorfon are commonly used as disinfectants and insecticide, sometimes in combination. However, improper use can result in biotoxicity and increased ecological risks. The liver plays a crucial role in detoxification, lipid metabolism, nutrient storage, and immune function in fish. Selecting the liver as the main target organ for research helps to gain an in-depth understanding of various aspects of fish physiology, health, and adaptability. In the present study, zebrafish were exposed to Cu (0.5 mg/L) and Tri (0.5 mg/L) alone and in combination for 21 days. The results demonstrate that both Cu and Tri caused hepatocyte structure damage in zebrafish after 21 days of exposure, with the combination showing an even greater toxicity. Additionally, the antioxidant and immune enzyme activities in zebrafish liver were significantly induced on both day 7 and day 21. A transcriptome analysis revealed that Cu and Tri, alone and in combination, impacted various physiological activities differently, including metabolism, growth, and immunity. Overall, Cu and Tri, either individually or in combination, can induce tissue damage by generating oxidative stress in the body, and the longer the exposure duration, the stronger the toxic effects. Moreover, the combined exposure to Cu and Tri exhibits enhanced toxicity. This study provides a theoretical foundation for the combined use of heavy metal disinfectants and other drugs.

Trichlorfon blocks androgen synthesis and metabolism in rat immature Leydig cells.

Trichlorfon is a widely used organophosphorus insecticide. It has been reported that it has reproductive toxicity to animal models. However, whether trichlorfon affects testosterone biosynthesis and metabolism remains unclear. In this study, we explored the effects of trichlorfon on the steroidogenesis and the expression of genes in androgen biosynthetic and metabolic cascades in immature Leydig cells isolated from pubertal male rats. Immature Leydig cells were treated with trichlorfon (0.5-50 µM) for 3 h. Trichlorfon significantly inhibited total androgen output under basal condition at 5 and 50 µM, and under LH- and cAMP-stimulated conditions at 50 µM. Trichlorfon also downregulated the expression of Star, Sod2, and Gpx1 and their proteins at 5 and 50 µM and the expression of Cyp11a1, Hsd3b1, Cyp17a1, and Srd5a1 at 50 µM. Trichlorfon significantly inhibited total androgen output at 50 µM, which was partially reversed by 400 µg/ml vitamin E, which alone had no effects on androgen output. In conclusion, trichlorfon downregulates the expression of steroidogenesis-related genes and antioxidants, which leads to a decrease in androgen production in rat immature Leydig cells.

Dynamics of dominant rhizospheric microbial communities responsible for trichlorfon absorption and translocation in maize seedlings.

In this study, the available phosphorus (AP) and TCF concentrations in soils and maize (Zea mays) seedling tissues were measured in response to escalating TCF concentrations during 216 hr of culture. Maize seedlings growth considerably enhanced soil TCF degradation, reaching the highest of 73.2% and 87.4% at 216 hr in 50 and 200 mg/kg TCF treatments, respectively, and increased AP contents in all the seedling tissues. Soil TCF was majorly accumulated in seedling roots, reaching maximum concentration of 0.017 and 0.076 mg/kg in TCF-50 and TCF-200, respectively. The hydrophilicity of TCF might hinder its translocation to the aboveground shoot and leaf. Using bacterial 16 S rRNA gene sequencing, we found that TCF addition drastically lessened bacterial community interactions and hindered the complexity of their biotic networks in rhizosphere than in bulk soils, leading to the homogeneity of bacterial communities that were resistant or prone to TCF biodegradation. Mantel test and redundancy analysis suggested a significant enrichment of dominant species Massilia belonging to Proteobacteria phyla, which in turn affecting TCF translocation and accumulation in maize seedling tissues. This study provided new insight into the biogeochemical fate of TCF in maize seedling and the responsible rhizobacterial community in soil TCF absorption and translocation.

Investigation of the transformation and toxicity of trichlorfon at the molecular level during enzymic hydrolysis of apple juice.

Trichlorfon is one of the most widely used organophosphorus pesticides in agriculture. In this study, the extent of transformation of trichlorfon to dichlorvos (DDVP), during the polygalacturonase (PG) treatment of apple pulp was monitored. A transformation pathway is proposed for trichlorfon molecules, based on density functional theory (DFT) calculations. The transformation of trichlorfon involves hydroxyl substitution and cleavage, which was confirmed by molecular electrostatic potential (MEP) and frontier molecular orbital (FMO) theory. In addition, the toxicity of trichlorfon and its transformed products was analyzed using Ecological Structure Activity Relationships (ECOSAR) software. The binding sites of the two pesticides are located in the hydrophobic grooves of the acetylcholinesterase (AChE) active site region and both pesticides form hydrophobic interactions and hydrogen bonds with a large number of surrounding amino acid residues. DDVP binds more strongly with AChE, so it is a better AChE inhibitor and more toxic than trichlorfon.

Molecular characterization, expression and enzyme activity of three glutathione S-transferase genes from Eriocheir sinensis under pesticide stresses.

Glutathione S-transferases (GSTs) are a multifunctional protein superfamily that can catalyze the detoxification processes in an organism. In the present study, we determined the structure and function of GSTs in Chinese mitten crab (Eriocheir sinensis) by gene cloning, expression, and enzyme activity in order to investigate the metabolic detoxification of GSTs in the hepatopancreas and muscles under three pesticide (trichlorfon, ß-cypermethrin and avermectin) stresses. Multiple sequence alignment analysis showed that all the three Es-GST genes possessed N-terminal, and C-terminal domain as well as G-binding sites, while Es-GST2 and Es-GST3 contained Mu-type GST-specific Mu-loop structures. Phylogenetic tree analysis revealed that the three Es-GSTs belonged to the Mu-type GST of crustaceans. The quantitative real-time PCR revealed that the three Es-GSTS were expressed in 9 tissues of Eriocheir sinensis, with highest expression in hepatopancreas and muscle. The expression of the three Es-GSTS significantly increased in the hepatopancreas and muscle under the three pesticide stresses compared to the control group, and a steady increase in GST activity was observed. The study showed that the three Es-GSTs belong to the Mu-type GST of the crustaceans and might play an important role in the metabolic detoxification in Eriocheir sinensis.

Toxicity, Biodegradation, and Metabolic Fate of Organophosphorus Pesticide Trichlorfon on the Freshwater Algae Chlamydomonas reinhardtii.

This study investigated the toxicity of trichlorfon (TCF) to the freshwater algae Chlamydomonas reinhardtii, as well as its biodegradation and metabolic fate. The growth of C. reinhardtii decreased with increasing TCF concentration, and the maximum inhibition ratio was 51.3% at 200 mg L-1 TCF compared to the control. Analyses of pigment content, chlorophyll fluorescence, and antioxidant enzymes indicated that C. reinhardtii can produce resistance and acclimatize to the presence of TCF. The variations in pH during cultivation suggested that photosynthetic microalgae have innate advantages over bacteria and fungi in remediating TCF. A 100% biodegradation rate was achieved at a maximum concentration of 100 mg L-1 TCF. Ten metabolites were identified by GC-MS, and the degradation pathways of TCF by the algae were proposed. This research demonstrated that C. reinhardtii is highly tolerant to and can efficiently degrade TCF. Thus, C. reinhardtii can be used to remove traces of TCF from natural water environments and to treat TCF-contaminated wastewater.

Bioremediation of cadmium-trichlorfon co-contaminated soil by Indian mustard (Brassica juncea) associated with the trichlorfon-degrading microbe Aspergillus sydowii: Related physiological responses and soil enzyme activities.

Soil co-contaminated with heavy metals and organics is often difficult to remediate. In this study, pot experiments were conducted to investigate the concurrent removal of cadmium (Cd, two levels: CdL [10 mg kg-1] and CdH [50 mg kg-1]) and trichlorfon (TCF, 100 mg kg-1) from co-contaminated soil by comparing the following remediation methods: natural remediation (NR), soil inoculated with Aspergillus sydowii (AS), soil planted with Brassica juncea (BJ), and soil planted with B. juncea and inoculated with A. sydowii (BJ-AS). The physiological responses of B. juncea and soil enzyme activities after remediation were also studied. B. juncea grew well in co-contaminated soil at both Cd levels. The biomass and chlorophyll content of B. juncea in CdH soil were lower than those in CdL soil, whereas the malondialdehyde content and activities of catalase, peroxidase and superoxide dismutase of B. juncea in CdH soil were higher than those in CdL soil. Cd accumulation in B. juncea was high in CdH soil, whereas high Cd removal efficiency was observed in CdL soil. TCF could be thoroughly degraded within 35 days in NR at both Cd-level soils. AS, BJ and BJ-AS promoted TCF degradation and enhanced the activities of catalase, urease, sucrase and alkaline phosphatase in soil compared with the NR. BJ-AS showed the highest phytoextraction ratio (3.32% in CdL and 1.34% in CdH soil) and TCF degradation rate (half-life of 2.18 and 2.37 days in CdL and CdH soil, respectively). These results demonstrate that BJ-AS could effectively remove Cd and TCF from soil and is thus a feasible technology for the bioremediation of these co-contaminated soil.

Simultaneous degradation of trichlorfon and removal of Cd(II) by Aspergillus sydowii strain PA F-2.

Co-contamination with heavy metals and pesticides is a severe environmental problem, but little information is available regarding the simultaneous removal of these pollutants. In this study, we showed that Aspergillus sydowii strain PA F-2 isolated from soil contaminated with heavy metal and pesticides can simultaneously degrade trichlorfon (TCF) and adsorb Cd(II) from mineral salt medium. The maximum removal rates for TCF and Cd(II) were 55.52% and 57.90%, respectively, in the treatment containing 100 mg L-1 TCF and 2 mg L-1 Cd(II). As the initial Cd(II) concentration increased (2, 5, and 10 mg L-1), the PA F-2 biomass, TCF degradation rate, and Cd(II) adsorption efficiency decreased, whereas the Cd(II) adsorption capacity by PA F-2 increased. The addition of exogenous glucose and sucrose significantly increased the PA F-2 biomass as well as the removal of TCF and Cd(II). Moreover, the TCF degradation pathway and Cd(II) adsorption mechanism were investigated by gas chromatography-mass spectrometry, scanning electron microscopy, and Fourier transform infrared spectroscopy. These results suggest that PA F-2 has potential applications in the bioremediation of TCF and Cd(II) co-contamination.

Construction of Persistent Luminescence-Plastic Antibody Hybrid Nanoprobe for In Vivo Recognition and Clearance of Pesticide Using Background-Free Nanobioimaging.

We prepared a specific adsorptive nanocarrier for pesticide due to its challenge to cleanup and low detoxification in the treatment after intake, whether intentional or by mistake. We modified the plastic antibody (molecularly imprinted polymer (MIP)) on the surface of persistent luminescence nanoparticle (La3Ga5GeO14: Cr3+, Zn2+, LGGO) as the specific adsorptive nanocarrier for toxic molecules and realized the nanocarrier was widely distributed for absorbing pesticide and real-time in vivo bioimaging. We used LGGO as the core and trichlorphon as the template to prepare the plastic antibody nanocarrier. After in vivo bioimaging and biodistribution of mice, LGGO@MIP could be distributed evenly in the gastrointestinal tract, circulated in the blood for a long time, and finally excreted to achieve the adsorption and removal of pesticide in the body. The LGGO@MIP nanocarrier prepared in this study opens a new way for the treatment of poisoning.

Gut symbiont enhances insecticide resistance in a significant pest, the oriental fruit fly Bactrocera dorsalis (Hendel).

BACKGROUND: Symbiotic bacteria affect insect physiology and ecology. They may also mediate insecticide resistance within their hosts and thereby impact pest and vector control practices. Here, we document a novel mechanism of insecticide resistance in which a gut symbiont of the tephritid pest fruit fly Bactrocera dorsalis enhances resistance to the organophosphate insecticide trichlorphon. RESULTS: We demonstrated that the gut symbiont Citrobacter sp. (CF-BD) plays a key role in the degradation of trichlorphon. Based on a comparative genomics analysis with other Citrobacter species, phosphatase hydrolase genes were identified in CF-BD. These CF-BD genes had higher expression when trichlorphon was present. Bactrocera dorsalis inoculated with isolated CF-BD obtained higher trichlorphon resistance, while antibiotic-treated flies were less resistant confirming the key role of CF-BD in insecticide resistance. CONCLUSIONS: Our findings suggest that symbiont-mediated insecticide resistance can readily develop in B. dorsalis and may represent a more widely relevant insecticide resistance mechanism than previously recognized.

Sensitive inkjet printing paper-based colormetric strips for acetylcholinesterase inhibitors with indoxyl acetate substrate.

A new paper-based biosensing approach has been developed for sensitive and rapid detection of acetylcholinesterase (AChE) inhibitors. The biosensing zone of the paper strip is constructed with an inkjet printing method, and the biomolecule AChE is immobilized into two layers of biocompatible sol-gel-derived silica ink with a "sandwich" form. Indoxyl acetate (IDA) is used as a chromogenic substrate, which is colorless and can be catalytically hydrolyzed into blue-colored indigo dipolymer. When the enzymatic activity of AChE is inhibited after incubation with organophosphate pesticides (OPs), there is a decreased hydrolysis of IDA accompanying with a drop in color intensity. Paraoxon and trichlorfon are used as the representative OPs in the assay. Due to the low solubility and high molar absorption coefficient of the IDA dipolymer product, the paper-based strip can form a neat blue sensing zone and shows obviously improved sensitivity with a limit of detection (LOD) of 0.01ngmL-1 paraoxon and 0.04ngmL-1 trichlorfon (S/N=3) and the LODs for visual detection are 0.03ngmL-1 for paraoxon and 0.1ngmL-1 for trichlorfon comparing with the previously reported colorimetric methods. The concentrations of paraoxon in apple juice samples are also detected, and the results are in accord well with these results from high-performance liquid chromatography, showing great potential for on-site detection of OPs in practical application. The developed assay can be used to qualitatively and semiquantitatively estimate with naked eyes and quantitatively assess OPs through image analysis.

Performance of trichlorfon degradation by a novel Bacillus tequilensis strain PA F-3 and its proposed biodegradation pathway.

The novel trichlorfon (TCF)-degrading bacterium PA F-3, identified as Bacillus tequilensis, was isolated from pesticide-polluted soils by using an effective screening and domesticating procedure. The TCF biodegradation pathways of PA F-3 were also systematically elucidated. As revealed by high-performance liquid chromatography, the TCF residues in the mineral salt medium demonstrated that PA F-3 can utilize TCF as its sole carbon source and reach the highest degradation of 71.1 % at an initial TCF concentration of 200 mg/L within 5 days. The TCF degradation conditions were optimized using response surface methodology as follows: temperature, 28 °C; inoculum amount, 4 %; and initial TCF concentration, 125 mg/L. Biodegradation treatments supplemented with exogenous carbon sources and yeast extract markedly increased the microbial dry weights and TCF-degrading performance of PA F-3, respectively. Meanwhile, five metabolic products of TCF were identified through gas chromatography/mass spectrometry, and a biodegradation pathway was proposed. Results indicated that deoxidation and dehydration (including the cleavage of the P-C phosphonate bond and the C-O bond) were the preferred metabolic reactions of TCF in this TCF-degrading bacterium.

Biodegradation of the Organophosphate Trichlorfon and Its Major Degradation Products by a Novel Aspergillus sydowii PA F-2.

Trichlorfon (TCF) is an important organophosphate pesticide in agriculture. However, limited information is known about the biodegradation behaviors and kinetics of this pesticide. In this study, a newly isolated fungus (PA F-2) from pesticide-polluted soils was identified as Aspergillus sydowii on the basis of the sequencing of internal transcribed spacer rDNA. This fungus degraded TCF as sole carbon, sole phosphorus, and sole carbon-phosphorus sources in a mineral salt medium (MSM). Optimal TCF degradation conditions were determined through response surface methodology, and results also revealed that 75.31% of 100 mg/L TCF was metabolized within 7 days. The degradation of TCF was accelerated, and the mycelial dry weight of PA F-2 was remarkably increased in MSM supplemented with exogenous sucrose and yeast extract. Five TCF metabolic products were identified through gas chromatography-mass spectrometry. TCF could be initially hydrolyzed to dichlorvos and then be degraded through the cleavage of the P-C bond to produce dimethyl hydrogen phosphate and chloral hydrate. These two compounds were subsequently deoxidized to produce dimethyl phosphite and trichloroethanal. These results demonstrate the biodegradation pathways of TCF and promote the potential use of PA F-2 to bioremediate TCF-contaminated environments.

[Study on decomposed products of trichlorfon in process of gas chromatographic analysis by mass spectrometry].

The decomposed products of trichlorfon in gas chromatographic analysis were identified by mass spectrometry (MS). After MS interpretation, three decomposed products, trichloroacetaldehyde, dimethyl phosphite and dichlorvos were identified. The effects of gas chromatographic conditions on decomposed products of trichlorfon, e. g. injection temperature, injection mode and oven ramp, were studied. The experiments showed that all of the factors have effects on decomposed products of trichlorfon, however, the injection temperature is the key factor to cause trichlorfon being decomposed. The higher the injection temperature is, the bigger the amount of trichlorfon being decomposed. When the injection temperature was raised from 150 degrees C to 250 degrees C, the remaining trichlorfon fell from 86% to 20%. Therefore, on-cold column injection mode gas chromatography or high performance liquid chromatography was recommended for exact quantification of trace trichlorfon.

The effect of trichlorfon and other organophosphates on prenatal brain development in the guinea pig.

The organophosphates trichlorfon, dichlorvos, dimethoate, soman, triortho-cresyl phosphate (TOCP), and the diethoxy-analogue of trichlorfon (O,O-diethyl 2,2,2-trichloro-1-hydroxyethylphosphonate, ethyl-trichlorfon), were administered to guinea pigs between day 42 and 46 of gestation. When the offsprings were examined at birth, there was a severe reduction in brain weight in the case of trichlorfon and dichlorvos, but not after treatment with the other organophosphates. The reduction in weight was most pronounced for cerebellum, medulla oblongata, thalamus/hypothalamus and quadrigemina. The effect was less marked for cerebral cortex and hippocampus. Since soman, a potent anticholinesterase, and TOCP, an inhibitor of neuropathy target esterase, did not show any effects, this excludes that the brain hypoplasia can be caused by inhibition of these two enzymes. Further, the lack of effect with ethyl-trichlorfon has shed some light on the part of the trichlorfon molecule which could be involved in the formation of the hypoplasia. It is suggested that alkylation of DNA may be involved in the development of the lesion. The possible consequences for a teratogenic effect of trichlorfon and dichlorvos on humans are discussed.

Clinical pharmacokinetics of cholinesterase inhibitors.

This review deals mainly with the pharmacokinetics of the reversible quaternary cholinesterase inhibitors neostigmine, pyridostigmine and edrophonium, which are mainly used to antagonise non-depolarising neuromuscular blockade in general anaesthesia and in the symptomatic treatment of myasthenia gravis. Only in the last few years, since the introduction of highly sensitive and selective analytical procedures based on gas and liquid chromatography, have proper pharmacokinetic studies of these drugs become possible. Rapid cooling and addition of internal standard to samples before freezing are important precautions in view of the poor stability of the cholinesterase inhibitors in plasma and blood. Plasma clearances of the reversible quaternary cholinesterase inhibitors are in the range 0.5 to 1.0 L/h/kg and their apparent volumes of distribution range from 0.5 to 1.7 L/kg. Accordingly, the drugs have short plasma elimination half-lives, in the order of 30 to 90 minutes. One to two hours after oral administration of 60 mg pyridostigmine, peak plasma concentrations of 40 to 60 micrograms/L are observed, whereas the plasma concentrations of neostigmine after a 30 mg oral dose are only 1 to 5 micrograms/L. The oral bioavailability of these hydrophilic ionised compounds is low: that of pyridostigmine is approximately 10% and the value for neostigmine is even lower. In spite of the short elimination half-life of pyridostigmine, intraindividual variations in plasma concentration during a dose interval are small in myasthenic patients receiving oral maintenance therapy, probably as a result of slow absorption from the gastrointestinal tract. Severely impaired renal function has been shown to prolong the elimination of neostigmine and pyridostigmine, while methylcellulose has been reported to inhibit the absorption of the latter drug completely. Other pharmacokinetic drug interactions suggested so far do not seem to be of clinical significance. Although a positive correlation has been demonstrated between the plasma concentrations of these drugs and their pharmacological effects as measured by a decrement in muscle response to repetitive nerve stimulation in a single muscle, this relationship is less clear when a global evaluation of muscular function in myasthenia gravis is used. Pharmacokinetic studies of the tertiary reversible cholinesterase inhibitor physostigmine, an important tool in experimental cholinergic neuropharmacology, are still in their initial stages. This drug too is characterised by a short plasma elimination half-life of 20 to 30 minutes.(ABSTRACT TRUNCATED AT 400 WORDS)