-
Pesticide Biochemistry and Physiology May 2020Fluensulfone is a nematicide with a novel mode of action against plant parasitic nematodes. Here, we utilize in vitro hatching assays to investigate fluensufone's...
BACKGROUND
Fluensulfone is a nematicide with a novel mode of action against plant parasitic nematodes. Here, we utilize in vitro hatching assays to investigate fluensufone's ability to inhibit Globodera pallida hatching, relative to the efficacy of other distinct classes of nematicides.
RESULTS
Fluensulfone, abamectin, aldicarb and fluopyram inhibit G. pallida hatching from cysts more potently than from isolated eggs. At 1 μM for cysts, the order of potency is fluensulfone> fluopyram> abamectin> aldicarb. At low concentrations of fluensulfone, inhibition of hatching is reversible, however, more than 50% of the juveniles that hatch from cysts pre-treated with fluensulfone have reduced motility. This is observed to a lesser extent with abamectin, fluopyram and aldicarb. When cysts are exposed to higher concentrations of fluensulfone (≥500 μM), abamectin (≥100 μM) and fluopyram (≥50 μM) inhibition of hatching is irreversible. This results from the loss of encysted juvenile structure giving rise to a granulated appearance consistent with necrosis, suggesting a nematicidal effect. Intriguingly, hatching initiated by root diffusate is arrested when egg populations are subsequently exposed to fluensulfone.
CONCLUSION
Fluensulfone, abamectin, fluopyram and aldicarb inhibit G. pallida hatching. Fluensulfone is a potent inhibitor of hatching and impacts on the viability of the J2 s emerging from the cysts. This activity, and the previously described impaired motility and metabolism of hatched juveniles, show that fluensulfone's distinct mode of action among existing nematicides intersects at two pivotal steps of the parasitic life cycle.
Topics: Aldicarb; Animals; Benzamides; Ivermectin; Pyridines; Sulfones; Thiazoles; Tylenchoidea
PubMed: 32359561
DOI: 10.1016/j.pestbp.2020.02.007 -
Journal of Nematology 2020(peanut root-knot nematode (PRKN)) is a major pest of peanut. Nematicide application is an important tool for the management of PRKN. Nematicides with minimal effects...
(peanut root-knot nematode (PRKN)) is a major pest of peanut. Nematicide application is an important tool for the management of PRKN. Nematicides with minimal effects on free-living nematodes are desired. Fluopyram nematicide is recently introduced in peanut production and needs to be assessed. The objective of this research is to evaluate fluopyram and the established nematicides 1,3-Dichloropropene (1,3-D) and aldicarb for efficacy at managing PRKN and impacts on free-living nematodes. Nematicides were evaluated in field studies in 2017 and 2018 conducted in commercial peanut fields. All nematicides increased peanut yield in 2017 compared with untreated control, but did not affect soil PRKN abundances or root galling. In 2018, PRKN infestation was too low to accurately assess PRKN management by nematicides. Aldicarb and fluopyram did not affect any free-living nematode trophic group or individual genera. In contrast, 1,3-D decreased total fungivore and fungivore genera and soil abundances, but did not affect bacterivores, omnivore-predators, total herbivores, or any other nematode genera. In summary, 1,3-D, but not aldicarb or fluopyram, had non-target effects on free-living nematodes, particularly fungivores. (peanut root-knot nematode (PRKN)) is a major pest of peanut. Nematicide application is an important tool for the management of PRKN. Nematicides with minimal effects on free-living nematodes are desired. Fluopyram nematicide is recently introduced in peanut production and needs to be assessed. The objective of this research is to evaluate fluopyram and the established nematicides 1,3-Dichloropropene (1,3-D) and aldicarb for efficacy at managing PRKN and impacts on free-living nematodes. Nematicides were evaluated in field studies in 2017 and 2018 conducted in commercial peanut fields. All nematicides increased peanut yield in 2017 compared with untreated control, but did not affect soil PRKN abundances or root galling. In 2018, PRKN infestation was too low to accurately assess PRKN management by nematicides. Aldicarb and fluopyram did not affect any free-living nematode trophic group or individual genera. In contrast, 1,3-D decreased total fungivore and fungivore genera and soil abundances, but did not affect bacterivores, omnivore-predators, total herbivores, or any other nematode genera. In summary, 1,3-D, but not aldicarb or fluopyram, had non-target effects on free-living nematodes, particularly fungivores.
PubMed: 32298058
DOI: 10.21307/jofnem-2020-028 -
Molecular and Biochemical Parasitology May 2020The ACC-1 family of cys-loop receptors are ligand-gated chloride channels sensitive to acetylcholine (ACh), and are only present in invertebrates. Studies of this family...
The ACC-1 family of cys-loop receptors are ligand-gated chloride channels sensitive to acetylcholine (ACh), and are only present in invertebrates. Studies of this family of inhibitory receptors has provided insight into how they bind and respond to ACh in a manner vastly different from nicotinic acetylcholine receptors and appear to be present in tissues that are relevant to anthelmintic action. Here, we have identified two members of the ACC-1 family from the parasitic nematode Haemonchus contortus, Hco-LGC-46 and Hco-ACC-4. Hco-LGC-46 is an ACC subunit that has never been previously expressed and pharmacologically characterized. We found that Hco-LGC-46 when expressed in Xenopus laevis oocytes forms a functional homomeric channel that is responsive to the cholinergic agonists ACh and methylcholine. hco-lgc-46 expressed in a C. elegans lgc-46 null strain (ok2900) suppressed hypersensitivity to aldicarb in a manner similar to cel-lgc-46. It was also found that Hco-LGC-46 assembles with Hco-ACC-1 and produces a receptor that is over 5-fold more sensitive to ACh and responds to the cholinergic agonists methycholine and carbachol. In contrast, the co-expression of Hco-LGC-46 with Hco-ACC-4 resulted in non-functional channels in oocytes. Hco-ACC-4 also appears to form heteromeric channels with a previously characterized subunit, Hco-ACC-2. Co-expression of Hco-ACC-4 with Hco-ACC-2 resulted in a functional heteromeric channel with an EC value similar to that of the Hco-ACC-2 homomeric channel. However, the maximum currents generated in the ACC-4/ACC-2 channel were significantly (p < 0.005) lower than those from the ACC-2 homomeric channel. Overall, this is the first report confirming that lgc-46 encodes an acetylcholine-gated chloride channel which when co-expressed with acc-4 results in reduced receptor function or trafficking in oocytes.
Topics: Acetylcholine; Action Potentials; Aldicarb; Amino Acid Sequence; Animals; Anthelmintics; Caenorhabditis elegans; Carbachol; Chloride Channels; Choline; Cloning, Molecular; Cysteine Loop Ligand-Gated Ion Channel Receptors; Gene Expression; Genetic Vectors; Haemonchus; Helminth Proteins; Models, Molecular; Oocytes; Protein Structure, Secondary; Recombinant Proteins; Sequence Alignment; Sequence Homology, Amino Acid; Xenopus laevis
PubMed: 32268182
DOI: 10.1016/j.molbiopara.2020.111276 -
Proceedings of the National Academy of... Mar 2020Fungal predatory behavior on nematodes has evolved independently in all major fungal lineages. The basidiomycete oyster mushroom is a carnivorous fungus that preys on...
Fungal predatory behavior on nematodes has evolved independently in all major fungal lineages. The basidiomycete oyster mushroom is a carnivorous fungus that preys on nematodes to supplement its nitrogen intake under nutrient-limiting conditions. Its hyphae can paralyze nematodes within a few minutes of contact, but the mechanism had remained unclear. We demonstrate that the predator-prey relationship is highly conserved between multiple species and a diversity of nematodes. To further investigate the cellular and molecular mechanisms underlying rapid nematode paralysis, we conducted genetic screens in and isolated mutants that became resistant to We found that paralysis-resistant mutants all harbored loss-of-function mutations in genes required for ciliogenesis, demonstrating that the fungus induced paralysis via the cilia of nematode sensory neurons. Furthermore, we observed that caused excess calcium influx and hypercontraction of the head and pharyngeal muscle cells, ultimately resulting in rapid necrosis of the entire nervous system and muscle cells throughout the entire organism. This cilia-dependent predatory mechanism is evolutionarily conserved in , a nematode species estimated to have diverged from 280 to 430 million y ago. Thus, exploits a nematode-killing mechanism that is distinct from widely used anthelmintic drugs such as ivermectin, levamisole, and aldicarb, representing a potential route for targeting parasitic nematodes in plants, animals, and humans.
Topics: Animals; Caenorhabditis elegans; Calcium; Cilia; Muscle, Skeletal; Mycotoxins; Necrosis; Pleurotus
PubMed: 32123065
DOI: 10.1073/pnas.1918473117 -
ACS Omega Feb 2020Pesticides are used in agriculture for crop production enhancement by controlling pests, but they have acute toxicological effects on other life forms. Thus, it becomes...
Pesticides are used in agriculture for crop production enhancement by controlling pests, but they have acute toxicological effects on other life forms. Thus, it becomes imperative to detect their concentration in food products in a fast and accurate manner. In this study, ZnO nanoparticles (ZnO nps) have been used as optical sensors for the detection of pesticide Aldicarb via a photoinduced electron transfer (PET) route. ZnO nps were synthesized directly by calcining zinc acetate at 450, 500, and 550 °C for 2 h. ZnO nps were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and UV-vis absorption and photoluminescence (PL) spectroscopies to study the phase, crystallinity, shape, morphology, absorbance, and fluorescence of the prepared ZnO nps. XRD and Raman studies confirmed the crystalline nature of ZnO nps. The average crystallite size obtained was 13-20 nm from the XRD study. The SEM study confirmed spherical-shaped ZnO nps with average sizes in the range of 70-150 nm. The maximum absorbance was obtained in the 200-500 nm regions with a prominent peak absorbance at 372 nm from UV-vis spectra. The corresponding band gap for ZnO nps was calculated using Tauc's plots and was found to be 3.8, 3.67, and 3.45 eV for the 450, 500, and 550 °C calcined samples, respectively. The fluorescence spectra showed an increase in the intensity along with the increase in the size of ZnO nps. The ZnO nps (samples calcined at 500 and 550 °C) exhibited a response toward Aldicarb, owing to their pure phase and higher PL intensity. Both the samples showed systematic detection of Aldicarb in the range of 250 pM to 2 nM (500 °C) and 250 pM to 5 nM (550 °C). Among the various quenching mechanisms, PET was found to be the dominant process for the detection of Aldicarb. This method can be used for the detection of Aldicarb in real (food) samples using a portable fluorimeter.
PubMed: 32095679
DOI: 10.1021/acsomega.9b01987 -
Chemico-biological Interactions Feb 2020In this study, we assessed the efficacy of the Reactive Skin Decontamination Lotion (RSDL®) Kit against parathion and aldicarb pesticide dermal exposure in a guinea pig...
In this study, we assessed the efficacy of the Reactive Skin Decontamination Lotion (RSDL®) Kit against parathion and aldicarb pesticide dermal exposure in a guinea pig model. The pesticides inhibit acetylcholinesterase (AChE) leading to signs and symptoms of hyperactivity of organs due to accumulation of acetylcholine. The RSDL Kit has been shown to physically remove and chemically degrade chemical warfare agents. Degradation occurs from a nucleophilic substitution reaction between an active ingredient in the RSDL lotion, potassium 2,3-butanedione monoximate (KBDO), with susceptible sites in these compounds. In the present study, guinea pigs dermally exposed to parathion and aldicarb were decontaminated with RSDL to mitigate the toxic effects of the pesticides. It is observed that animals exposed to 749 mg/kg of parathion (n = 3) died within 24 h without RSDL decontamination; however, RSDL-treated animals (n = 3) showed only mild signs of neurotoxicity. The RSDL-treated animals had an AChE inhibition of 0-58% while the untreated animals had up to 86% inhibition. Similarly, RSDL has been demostrated to prevent aldicarb neurotoxicity effects. The percent inhibition of AChE activity during the 24 h post challenge of 9 mg aldicarb/kg of animal weight ranged from 25% to 61% with severe signs of intoxication while only up to 5% with mild or no signs of intoxication in the case of RSDL-decontaminated animals. Generally, it has been shown that the toxic effects of the organophosphate and carbamate pesticides can be prevented via decontamination using the RSDL Kit.
Topics: Aldicarb; Animals; Decontamination; Guinea Pigs; Insecticides; Parathion; Skin Care; Skin Cream
PubMed: 32044340
DOI: 10.1016/j.cbi.2020.108980 -
APL Bioengineering Mar 2020In , optogenetic stimulation has been widely used to assess neuronal function, control animal movement, or assay circuit responses to controlled stimuli. Most studies...
In , optogenetic stimulation has been widely used to assess neuronal function, control animal movement, or assay circuit responses to controlled stimuli. Most studies are performed on single animals and require high-end components such as lasers and shutters. We present an accessible platform that enables controlled optogenetic stimulation of in two modes: single animal stimulation with locomotion tracking and entire population stimulation for neuronal exercise regimens. The system consists of accessible electronic components: a high-power light-emitting diode, Arduino board, and relay are integrated with MATLAB to enable programmable optogenetic stimulation regimens. This system provides flexibility in optogenetic stimulation in freely moving animals while providing quantitative information of optogenetic-driven locomotion responses. We show the applicability of this platform in single animals by stimulation of cholinergic motor neurons in and quantitative assessment of contractile responses. In addition, we tested synaptic plasticity by coupling the entire-population stimulation mode with measurements of synaptic strength using an aldicarb assay, where clear changes in synaptic strength were observed after regimens of neuronal exercise. This platform is composed of inexpensive components, while providing the illumination strength of high-end systems, which require expensive lasers, shutters, or automated stages. This platform requires no moving parts but provides flexibility in stimulation regimens.
PubMed: 31934682
DOI: 10.1063/1.5120002 -
The Science of the Total Environment Mar 2020To protect ecosystems, threshold concentrations (e.g., HC) for chemicals are often derived using the toxicity data obtained at fixed times. Since the toxicity (e.g., LC)...
To protect ecosystems, threshold concentrations (e.g., HC) for chemicals are often derived using the toxicity data obtained at fixed times. Since the toxicity (e.g., LC) usually decreases with exposure time, the threshold concentrations are expected to be time-dependent, giving rise to the uncertainty in the chemical environmental criteria. Here, using the LC data with at least 3 different exposure durations (24, 48 and 96 h) for compounds, we explored the time evolutions of HC across 20 chemicals. Results showed that all chemical's HC decreased with time, but their decreasing rates of HC (k) are significantly different: for some chemicals the k are lower than 0.001 (e.g., methoxychlor and dieldrin), while for some chemicals the k are higher than 0.05 (e.g., PCP and aldicarb). Furthermore, we found that k is negatively related to the bioconcentration factors (BCF), and positively related to the damage recovery rates (k). Our work demonstrated that time is an important source of the ecological threshold uncertainty, and this uncertainty is associated with chemical-specific toxicokinetic and toxicodynamic characteristics. We recommend that to effectively protect the ecological communities, higher assessment factor should be adopted in deriving the acute environmental criteria for these chemicals with high BCF and low k, fluoranthene and diazinon.
PubMed: 31812410
DOI: 10.1016/j.scitotenv.2019.135234 -
Heliyon Nov 2019Carbamates are synthetic pesticides, extensively used throughout the world due to their broad specificity against various insect pests. However, their enormous and...
Carbamates are synthetic pesticides, extensively used throughout the world due to their broad specificity against various insect pests. However, their enormous and inadequate use have made them a potential threat to the environment. At low temperature, degradation of carbamates becomes difficult mainly because of low biological activity. In the present study, we isolated a bacterial strain from a low temperature climate where the methylated carbamates are used for crop protection. The bacterium, was identified as (TA3) by 16S rRNA analysis. Degradation experiments with both free and immobilized cells in minimal salt medium indicated that the strain TA3 utilized carbaryl, carbofuran and aldicarb as both carbon and nitrogen source. TA3 can grow well at 4 °C and demonstrated the ability to degrade three carbamates (50 μgml) at low temperature. The immobilized cells were found more efficient than their free cells counter parts. Immobilized cells has ability to degrade 100% of carbamates at 30 °C while 80% at 4 °C but incase of their free cells counter parts the efficiency to degrade carbamates was less which was 60% at 4 °C and 80% at 30 °C. TA3 free cellsextract also depicted high activity against all the three carbamates even at 4 °C indicating a possible enzymatic mechanism of degradation.
PubMed: 31768430
DOI: 10.1016/j.heliyon.2019.e02740 -
Ecotoxicology and Environmental Safety Feb 2020A novel carbofuran-degrading strain CFD-1 was isolated and preliminarily identified as Sphingbium sp. This strain was able to utilize carbofuran as the sole carbon...
A novel carbofuran-degrading strain CFD-1 was isolated and preliminarily identified as Sphingbium sp. This strain was able to utilize carbofuran as the sole carbon source for growth. The carbofuran hydrolase gene cehA was cloned from strain CFD-1 and expressed in Escherichia coli. CehA could hydrolyze carbamate pesticides including carbofuran and carbaryl efficiently, while it showed poor hydrolysis ability against isoprocarb, propoxur, oxamyl and aldicarb. CehA displayed maximal enzymatic activity at 40 °C and pH 7.0. The apparent Km and Kcat values of CehA for carbofuran were 133.22 ± 5.70 μM and 9.48 ± 0.89 s-1, respectively. The site-directed mutation experiment showed that His313, His315, His453 and His495 played important roles in the hydrolysis of carbofuran by CehA. Furthermore, the sequence of cehA is highly conserved among different carbofuran-degrading strains, and there are mobile elements around cehA, indicating that it may be transferred horizontally between different strains.
Topics: Amino Acids; Biodegradation, Environmental; Carbamates; Carbaryl; Carbofuran; Hydrolases; Hydrolysis; Pesticides; Sphingomonadaceae
PubMed: 31759739
DOI: 10.1016/j.ecoenv.2019.109938