Contribution of Immune Responses to the Cardiotoxicity and Hepatotoxicity of Deltamethrin in Early Life Stage Zebrafish (Danio rerio).

Deltamethrin (DM) is a widely used insecticide that has demonstrated developmental toxicity in the early life stages of fish. To better characterize the underlying mechanisms, embryos from Tg(cmlc2:RFP), Tg(apo14:GFP), and Tg(mpx:GFP) transgenic strains of zebrafish were exposed to nominal DM concentrations of 0.1, 1, 10, 25, and 50 µg/L until 120 h post-fertilization (hpf). Heart size increased 56.7%, and liver size was reduced by 17.1% in zebrafish exposed to 22.7 and 24.2 µg/L DM, respectively. RNA sequencing and bioinformatic analyses predicted that key biological processes affected by DM exposure were related to inflammatory responses. Expression of IL-1 protein was increased by 69.0% in the 24.4 µg/L DM treatment, and aggregation of neutrophils in cardiac and hepatic histologic sections was also observed. Coexposure to resatorvid, an anti-inflammatory agent, mitigated inflammatory responses and cardiac toxicity induced by DM and also restored liver biomass. Our data indicated a complex proinflammatory mechanism underlying DM-induced cardiotoxicity and hepatotoxicity which may be important for key events of adverse outcomes and associated risks of DM to early life stages of fish.

Aquatic and sediment ecotoxicity data of difenoconazole and its potential environmental risks in ponds bordering rice paddies.

Difenoconazole has a widespread agricultural use to control fungal diseases in crops, including rice. In edge-of-field surface waters the residues of this lipophilic fungicide may be toxic to both pelagic and benthic organisms. To allow an effect assessment we mined the regulatory and open literature for aquatic toxicity data. Since published sediment toxicity data were scarce we conducted 28 d sediment-spiked toxicity test with 8 species of benthic macroinvertebrates. Ecotoxicological threshold levels for effects were assessed by applying the species sensitivity distribution approach. Based on short-term L(E)C50's for aquatic organisms from water-only tests an acute Hazardous Concentration to 5% of the species (HC5) of 100 µg difenoconazole/L was obtained, while the HC5 based on chronic NOEC values was a factor of 104 lower (0.96 µg difenoconazole/L). For benthic macroinvertebrates the chronic HC5, based on 28d-L(E)C10 values, was 0.82 mg difenoconazole/kg dry weight sediment. To allow a risk assessment for water- and sediment-dwelling organisms, exposure concentrations were predicted for the water and sediment compartment of an edge-of-field pond bordering rice paddies treated with difenoconazole using the Chinese Top-Rice modelling approach, the Chinese Nanchang exposure scenario and the Equilibrium Partitioning theory. It appeared that in the vast majority of the 20 climate years simulated, potential risks to aquatic and sediment organisms cannot be excluded. Although the HC5 values based on laboratory toxicity data provide one line of evidence only, our evaluation suggests population- and community-level effects on these organisms due to chronic risks in particular.

Antenna-Biased Odorant Receptor PstrOR17 Mediates Attraction of Phyllotreta striolata to (S)-Cis-Verbenol and (-)-Verbenone.

Phyllotreta striolata, the striped flea beetle, is one of the most destructive pests in Brassicaceae plants worldwide. Given the drawbacks associated with long-term use of chemical insecticides, green strategies based on chemical ecology are an effective alternative for beetle control. However, the lack of information on beetle ecology has hindered the development of effective biocontrol strategies. In this report, we identified two odorants, (S)-cis-verbenol and (-)-verbenone, which displayed significant attraction for P. striolata (p < 0.05), indicating their great potential for P. striolata management. Using the Drosophila "empty neuron" system, an antenna-biased odorant receptor, PstrOR17, was identified as responsible for the detection of (-)-verbenone and (S)-cis-verbenol. Furthermore, the interactions between PstrOR17 and (-)-verbenone or (S)-cis-verbenol were predicted via modeling and molecular docking. Finally, we used RNAi to confirm that PstrOR17 is essential for the detection of (-)-verbenone and (S)-cis-verbenol to elicit an attraction effect. Our results not only lay a foundation for the development of new and effective nonchemical insecticide strategies based on (S)-cis-verbenol and (-)-verbenone, but also provide new insight into the molecular basis of odorant recognition in P. striolata.

Single-cell transcriptome analysis reveals cellular and molecular alterations in small cell lung cancer tumors following chemotherapy.

Chemotherapy is the standard therapy for small cell lung cancer (SCLC), but relapse is common and the 2-year survival rate remains low. Given the contribution of the tumor microenvironment (TME) to cancer development and response to treatment, we analyzed here how chemotherapy alters the TME in SCLC using single-cell RNA sequencing. The comparison between neuroendocrine cells and other epithelial cells in five chemotherapy-naive patients identified upregulation of Notch-inhibiting genes, such as DLL3 and HES6. Analysis of genes differentially expressed between five patients receiving chemotherapy and five treatment-naive patients in cells in the TME showed that chemotherapy promoted antigen presentation and senescence in neuroendocrine cells, upregulated ID1 to enhance angiogenic activities of stalk-like endothelial cells and strengthened vascular endothelial growth factor signaling in lymphatic endothelial cells. Chemotherapy also promoted the remodeling of extracellular matrix by fibroblasts and upregulated interferon-mediated antitumor immune responses by B and T cells. Our single-cell transcriptome analysis provides insights into how chemotherapy affects the TME in SCLC, which may guide efforts to make therapy more effective.

Insights into the Binding Profile of Anti-chlorpyrifos Recombinant Antibodies: From Computational Simulation to Immunoassay Validation.

A novel virtual screening strategy was proposed for the profiling and discovery of active variable regions (VRs) that encode hapten-specific recombinant antibodies (rAbs). Chlorpyrifos, a hazardous organophosphorus pesticide, was selected as the target. First, a VR model-14G4 from anti-chlorpyrifos hybridoma was built via homology modeling. Its binding pattern toward seven organophosphorus analogues was assessed through virtual screening by performing molecular docking. Based on energy scoring, visual examination, and molecular interaction analysis, chlorpyrifos-methyl was also inferred as the high-affinity target for model-14G4 and was then confirmed via a non-competitive surface plasmon resonance (SPR) assay. Subsequently, we attempted to discover hapten-specific VRs by creating a collection of VR models for anonymous testing. Chlorpyrifos and model-14G4 were employed as the known hit and active VRs, respectively. After molecular docking, a novel anti-chlorpyrifos VR (model-1) was identified due to its satisfactory energy scoring and a similar binding pattern to the reference model-14G4. Expressed by HEK293(F) mammalian cells, the newly prepared full-length rAb-model-1 and rAb-14G4 exhibited high sensitivities for detecting chlorpyrifos by the indirect competitive enzyme-linked immunosorbent assay (ic-ELISA), with IC50 of 3.01 ng/mL and 42.82 ng/mL, respectively. They recognized chlorpyrifos-methyl with a cross-reactivity (CR) of 2.5-17.3%. Moreover, the binding properties of rAb-model-1 for recognizing chlorpyrifos and chlorpyrifos-methyl were confirmed via a non-competitive microscale thermophoresis (MST) method. Thus, the experimental results showed good agreement with computational outputs on antibody profiling. Furthermore, the recognition diversity of rAb-model-1 for chlorpyrifos and chlorpyrifos-methyl was studied via molecular dynamics simulation. Overall, the proposed study provides a versatile and economical strategy for antibody characterization and promotes the in vitro production of rAbs for pesticide monitoring.

Early detection and stratification of lung cancer aided by a cost-effective assay targeting circulating tumor DNA (ctDNA) methylation.

BACKGROUND: Detection of lung cancer at earlier stage can greatly improve patient survival. We aim to develop, validate, and implement a cost-effective ctDNA-methylation-based plasma test to aid lung cancer early detection. METHODS: Case-control studies were designed to select the most relevant markers to lung cancer. Patients with lung cancer or benign lung disease and healthy individuals were recruited from different clinical centers. A multi-locus qPCR assay, LunaCAM, was developed for lung cancer alertness by ctDNA methylation. Two LunaCAM models were built for screening (-S) or diagnostic aid (-D) to favor sensitivity or specificity, respectively. The performance of the models was validated for different intended uses in clinics. RESULTS: Profiling DNA methylation on 429 plasma samples including 209 lung cancer, 123 benign diseases and 97 healthy participants identified the top markers that detected lung cancer from benign diseases and healthy with an AUC of 0.85 and 0.95, respectively. The most effective methylation markers were verified individually in 40 tissues and 169 plasma samples to develop LunaCAM assay. Two models corresponding to different intended uses were trained with 513 plasma samples, and validated with an independent collection of 172 plasma samples. In validation, LunaCAM-S model achieved an AUC of 0.90 (95% CI: 0.88-0.94) between lung cancer and healthy individuals, whereas LunaCAM-D model stratified lung cancer from benign pulmonary diseases with an AUC of 0.81 (95% CI: 0.78-0.86). When implemented sequentially in the validation set, LunaCAM-S enables to identify 58 patients of lung cancer (90.6% sensitivity), followed by LunaCAM-D to remove 20 patients with no evidence of cancer (83.3% specificity). LunaCAM-D significantly outperformed the blood test of carcinoembryonic antigen (CEA), and the combined model can further improve the predictive power for lung cancer to an overall AUC of 0.86. CONCLUSIONS: We developed two different models by ctDNA methylation assay to sensitively detect early-stage lung cancer or specifically classify lung benign diseases. Implemented at different clinical settings, LunaCAM models has a potential to provide a facile and inexpensive avenue for early screening and diagnostic aids for lung cancer.

An oral phenylacrylic acid derivative suppressed hepatic stellate cell activation and ameliorated liver fibrosis by blocking TGF-ß1 signalling.

BACKGROUND AND AIMS: Liver fibrosis is an excessive wound-healing response governed by activated hepatic stellate cells (HSCs). To date, there is no drug available for liver fibrosis. Although ferulic acid (FA) has multiple pharmacological functions, its anti-hepatic fibrosis activity is weak. Based on the activity modification of the FA structure, we synthesized a series of phenylacrylic derivatives and found a superior compound, FA11. In this study, we investigated its antifibrotic effect and mechanism. METHODS: Activated HSC and CCl4 -induced mouse liver fibrosis were established and followed by FA11 treatment. Cell viability was measured by CCK-8 assay. Apoptosis and cell cycle analysis were conducted by flow cytometry. Western blot and Real-time qPCR were used to examine the expression of fibrotic and M1/M2-type macrophages markers. Degree of liver fibrosis was shown by histological staining. RESULTS: In vitro, FA11 inhibited TGF-ß1-induced LX-2 proliferation and led to apoptosis and cycle arrest. Furthermore, elevation of fibrotic markers in TGF-ß1-induced LX-2 and primary activated HSC was reversed by FA11. In vivo, FA11 administration alleviated collagen deposition and blocked HSC activation and epithelial-mesenchymal transition (EMT). Additionally, FA11 reduced macrophage infiltration in fibrotic liver and prevented macrophage polarization to a profibrotic phenotype. Meanwhile, the systemic toxicity of CCl4 was also ameliorated by FA11. Mechanistically, FA11 reversed the phosphorylation of canonical and noncanonical TGF-ß1 signalling, as well as FGFR1 signalling. CONCLUSIONS: We reported an oral phenylacrylic acid derivative, FA11, which showed excellent antifibrotic activity and was expected to be an anti-hepatic fibrosis candidate.

Leucine to tryptophane substitution in the pore helix IIP1 confer sodium channel resistance to pyrethroids and DDT.

Aedes aegypti is responsible for transmitting a variety of arboviral infectious diseases such as dengue and chikungunya. Insecticides, particularly pyrethroids, are used widely for mosquito control. However, intensive used of pyrethroids has led to the selection of kdr mutations on sodium channels. L982W, locating in the PyR1 (Pyrethroid receptor site 1), was first reported in Ae. aegypti populations collected from Vietnam. Recently, the high frequency of L982W was detected in pyrethroid-resistant populations of Vietnam and Cambodia, and also concomitant mutations L982W + F1534C was detected in both countries. However, the role of L982W in pyrethroid resistance remains unclear. In this study, we examined the effects of L982W on gating properties and pyrethroid sensitivity in Xenopus oocytes. We found that mutations L982W and L982W + F1534C shifted the voltage dependence of activation in the depolarizing direction, however, neither mutations altered the voltage dependence of inactivation. L982W significantly reduced channel sensitivity to Type I pyrethroids, permethrin and bifenthrin, and Type II pyrethroids, deltamethrin and cypermethrin. No enhancement was observed when synergized with F1534C. In addition, L982W and L982W + F1534C mutations reduced the channel sensitivity to DDT. Our results illustrate the molecular basis of resistance mediates by L982W mutation, which will be helpful to understand the interacions of pyrethroids or DDT with sodium channels and develop molecular markers for monitoring pest resistance to pyrethroids and DDT.

NETs promote pathogenic cardiac fibrosis and participate in ventricular aneurysm formation after ischemia injury through the facilitation of perivascular fibrosis.

Fibrosis has been widely investigated in acute phase of myocardial infarction (MI). However, the mechanism of sustained fibrosis after MI hasn't been elucidated, which eventually gives rise to ventricular aneurysm (VA) formation chronic while lethal. Neutrophil as vital cell facilitating the fibrotic repair after acute MI may not project its effect to chronic phase unless neutrophil extracellular traps (NETs) were secreted and accumulating. The aim of this study was to investigate whether NETs contribute to the sustained fibrosis and VA formation after MI. We identified NETs in ventricular aneurysm of patients. Accordingly, NETs increased in peripheral blood of VA patients. Moreover, in rat VA NETs were also identified. Stimulated by NETs, the migration of fibroblast was enhanced and the differentiation of cardiac myofibroblast was initiated. Smad, MAPK and RhoA signaling pathways were activated by NETs incubation. And additional deposition with DNase I to disrupt NETs and abrogated NETs induced fibrosis both in vivo and vitro. These results collectively demonstrate a novel profibrotic role for NETs in chronic cardiac fibrosis and VA formation.

Online Public Attention Toward Premature Ejaculation in Mainland China: Infodemiology Study Using the Baidu Index.

BACKGROUND: Premature ejaculation (PE) is one of the most described psychosocial stress and sexual complaints worldwide. Previous investigations have focused predominantly on the prospective identification of cases that meet researchers' specific criteria. The genuine demand from patients with regard to information on PE and related issues may thus be neglected. OBJECTIVE: This study aims to examine the online search trend and user demand related to PE on a national and regional scale using the dominant major search engine in mainland China. METHODS: The Baidu Index was queried using the PE-related terms for the period of January 2011 to December 2020. The search volume for each term was recorded to analyze the search trend and demographic distributions. For user interest, the demand and trend data were collected and analyzed. RESULTS: Of the 36 available PE search keywords, 4 PE searching topics were identified. The Baidu Search Index for each PE topic varied from 46.30% (86,840,487/187,558,154) to 6.40% (12,009,307/187,558,154). The annual percent change (APC) for the complaint topic was 48.80% (P<.001) for 2011 to 2014 and -16.82% (P<.001) for 2014 to 2020. The APC for the inquiry topic was 16.21% (P=.41) for 2011 to 2014 and -11.00% (P<.001) for 2014 to 2020. For the prognosis topic, the annual APC was 11.18% (P<.001) for 2011 to 2017 and -19.86% (P<.001) for 2017 to 2020. For the treatment topic, the annual APC was 14.04% (P<.001) for 2011 to 2016 and -38.83% (P<.001) for 2016 to 2020. The age distribution of those searching for topics related to PE showed that the population aged 20 to 40 years comprised nearly 70% of the total search inquiries (second was 17.95% in the age group younger than 19 years). People from East China made over 50% of the total search queries. CONCLUSIONS: The fluctuating online popularity of PE searches reflects the real-time population demands. It may help medical professionals better understand population interest, population concerns, regional variations, and gender differences on a nationwide scale and make disease-specific health care policies. The internet search data could be more reliable when the insufficient and lagging registry data are completed.

Fuziline alleviates isoproterenol-induced myocardial injury by inhibiting ROS-triggered endoplasmic reticulum stress via PERK/eIF2α/ATF4/Chop pathway.

Fuziline, an aminoalcohol-diterpenoid alkaloid derived from Aconiti lateralis radix preparata, has been reported to have a cardioprotective activity in vitro. However, the potential mechanism of fuziline on myocardial protection remains unknown. In this study, we aimed to explore the efficacy and mechanism of fuziline on isoproterenol (ISO)-induced myocardial injury in vitro and in vivo. As a result, fuziline effectively increased cell viability and alleviated ISO-induced apoptosis. Meanwhile, fuziline significantly decreased the production of ROS, maintained mitochondrial membrane potential (MMP) and blocked the release of cytochrome C, suggesting that fuziline could play the cardioprotective role through restoring the mitochondrial function. Fuziline also could suppress ISO-induced endoplasmic reticulum (ER) stress via the PERK/eIF2α/ATF4/Chop pathway. In addition, using ROS scavenger NAC could decrease ISO-induced apoptosis and block ISO-induced ER stress, while PERK inhibitor GSK2606414 did not reduce the production of ROS, indicating that excess production of ROS induced by ISO triggered ER stress. And fuziline protected against ISO-induced myocardial injury by inhibiting ROS-triggered ER stress. Furthermore, fuziline effectively improved cardiac function on ISO-induced myocardial injury in rats. Western blot analysis also showed that fuziline reduced ER stress-induced apoptosis in vivo. Above these results demonstrated that fuziline could reduce ISO-induced myocardial injury in vitro and in vivo by inhibiting ROS-triggered ER stress via the PERK/eIF2α/ATF4/Chop pathway.

The expression of soluble functional α7-nicotinic acetylcholine receptors in E. coli and its high-affinity binding to neonicotinoid pesticides.

Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels mediating fast cholinergic synaptic transmission in nervous system. In insects, nAChRs are the target sites for several naturally occurring and synthetic compounds, including the neonicotinoid insecticides. So far, one of the major strategies to explore the interaction of nAChR and ligands is based on the heterologous expression of nAChR, which is tough, and needs to be explored. In this study, we expressed and purified extracellular domain of rat a7 subunit (Rα7-ECD), the binding site of the ligands in E. coli and determined the interactions and kinetic constants of neonicotinoid insecticides with Rα7-ECD. The recombinant Rα7-ECD is water-soluble and appears to be correctly folded. The interactions of three neonicotinoid pesticides with Rα7-ECD were assessed by surface plasmon resonance (SPR) biosensor. The results revealed a fast association and fast disassociation binding mode of Rα7-ECD/pesticides complexes with the KD value of clothianidin (6.414E-9 M) > imidacloprid (9.030E-9 M) > acetamiprid (2.874E-6 M), respectively. This study demonstrated that the nAChR expressed from E. coli was functional, and SPR biosensor technology would be a good alternative for characterizing members of nAChR receptor family.

Characterization of Variable Region Genes and Discovery of Key Recognition Sites in the Complementarity Determining Regions of the Anti-Thiacloprid Monoclonal Antibody.

Sequence-defined recombinant antibodies (rAbs) have emerged as alternatives to hybridoma-secreted monoclonal antibodies (mAbs) for performing immunoassays. However, the polyploidy nature of hybridomas often leads to the coexistence of aberrant or non-specific functional variable region (VR) gene transcripts, which complicates the identification of correct VR sequences. Herein, we introduced the use of LC-MS/MS combined with next-generation sequencing to characterize VR sequences in an anti-thiacloprid mAb, which was produced by a hybridoma with genetic antibody diversity. The certainty of VR sequences was verified by the functional analysis based on the recombinant antibody (rAb) expressed by HEK293 mammalian cells. The performance of the rAb was similar to that of the parental mAb, with IC50 values of 0.73 and 0.46 µg/L as measured by ELISAs. Moreover, molecular docking analysis revealed that Ser52 (H-CDR2), Trp98, and Trp93 (L-CDR3) residues in the complementarity determining regions (CDRs) of the identified VR sequences predominantly contributed to thiacloprid-specific recognition through hydrogen bonds and the CH-π interaction. Through single-site-directed alanine mutagenesis, we found that Trp98 and Trp93 (L-CDR3) showed high affinity to thiacloprid, while Ser52 (H-CDR2) had an auxiliary effect on the specific binding. This study presents an efficient and reliable way to determine the key recognition sites of hapten-specific mAbs, facilitating the improvement of antibody properties.

Cucurbitacin I induces pro-death autophagy in A549 cells via the ERK-mTOR-STAT3 signaling pathway.

Natural products are a great source of cancer chemotherapeutic agents. In the present study, the anticancer effects of cucurbitacin I on A549 cells were investigated. Cucurbitacin I decreased cell viability, inhibited colony formation, and induced apoptosis in A549 cells. Cucurbitacin I caused accumulation of autophagosome and dose-dependent expression of LC3II protein. Autophagy inhibitors 3-methyladenine (3-MA) inhibited autophagy induced by cucurbitacin I and relieved cucurbitacin I-triggered cell death and apoptosis in A549 Cells. Cucurbitacin I treatment inhibits the ERK activation and the downstream phosphorylation level of mTOR and STAT3, but not the PI3K/Akt pathway. Furthermore, treatment with the mTOR activator MHY-1485, which also suppressed cucurbitacin I-induced LC3II expression, and also reversed cucurbitacin I-induced cell death and apoptosis. Taken together, these results suggest that cucurbitacin I induced pro-death autophagy through ERK/mTOR/STAT3 signaling cascade in A549 cells.

Biotoxin Tropolone Contamination Associated with Nationwide Occurrence of Pathogen Burkholderia plantarii in Agricultural Environments in China.

Tropolone, a biotoxin produced by the agricultural pathogen Burkholderia plantarii, exerts cytotoxicity toward a wide array of biota. However, due to the lack of quantitative and qualitative approach, both B. plantarii occurrence and tropolone contamination in agricultural environments remain poorly understood. Here, we presented a sensitive and reliable method for detection of B. plantarii in artificial, plant, and environmental matrices by tropolone-targeted gas chromatography-triple-quadrupole tandem mass spectrometry analysis. Limits of detection for B. plantarii and tropolone were 10 colony-forming units (CFU)/mL and 0.017 µg/kg, respectively. In a series of simulation trials, we found that B. plantarii from 10 to 108 CFU/mL produced tropolone between 0.006 and 107.8 mg/kg in a cell-population-dependent manner, regardless of habitat. Correlation analysis clarified a reliable reflection of B. plantarii density by tropolone level with R2 values from 0.9201 to 0.9756 ( p < 0.01). Through a nationwide pilot study conducted in China, tropolone contamination was observed at 0.014-0.157 mg/kg in paddy soil and rice grains, and subsequent redundancy analysis revealed soil organic matter to be a dominant environmental factor, having a positive correlation with tropolone contamination. In this context, our results imply that potential ecological and dietary risks posed by long-term exposure to trace levels of tropolone contamination are of concern.

Binding properties of broad-specific monoclonal antibodies against three organophosphorus pesticides by a direct surface plasmon resonance immunosensor.

In this study, heterologous indirect competitive enzyme-linked immunosorbent assay (icELISA) was introduced into the screening of hybridomas for the development of broad-specific monoclonal antibodies (mAbs) against organophosphorus (OP) pesticides. After immunization, two formats of icELISA based on the homologous hapten antigen and four heterologous hapten antigens were conducted for hybridoma screening. Two mAbs 2G6 and 7B2 with good recognition toward three OP pesticides (parathion, methyl-parathion, and fenitrothion) were produced. Results of the icELISA showed that the two mAbs exhibited high sensitivity against three OP pesticides, with IC50 ranging from 2.93 to 19.71 ng mL-1. Moreover, a non-competitive surface plasmon resonance (SPR) immunosensor was used for characterizing the binding properties of the mAbs to OP pesticides. After kinetic analysis, equilibrium dissociation constant (KD) values of mAbs 2G6 and 7B2 were calculated as 1.45 × 10-9 M and 4.26 × 10-9 M for parathion, 6.75 × 10-9 M and 4.17 × 10-9 M for methyl-parathion, and 2.44 × 10-8 M and 1.19 × 10-8 M for fenitrothion, respectively. Whereas, both icELISA and SPR-based immunoassay indicated that the two mAbs could not recognize other five OP analogs. Since SPR-based immunoassay provides comprehensive information of two molecules directly interacting with each other, it is a valuable tool during the development and characterization of broad-specific mAbs. Graphical abstract ᅟ.

Action of six pyrethrins purified from the botanical insecticide pyrethrum on cockroach sodium channels expressed in Xenopus oocytes.

Pyrethrin I, pyrethrin II, cinerin I, cinerin II, jasmolin I and jasmolin II are six closely related insecticidal active esters, known as pyrethrins, found in the pyrethrum extract from the dry flowers of Tanacetum cinerariifolium. The chemical structures of the six compounds differ only in the terminal moieties at the acid and alcohol ends, but the compounds' in vivo toxicities are substantially different. Pyrethrins are lead compounds for pyrethroids, a large family of synthetic insecticides that alter nerve functions by prolonging the opening of voltage-gated sodium channels. However, data on the mechanism of action of natural pyrethrins are very limited. In this study, we examined the actions of all six pyrethrins on cockroach sodium channels expressed in Xenopus oocytes. Although the six compounds showed comparable potencies in inhibiting the inactivation of sodium channels, they had greatly variable potencies in inhibiting channel deactivation. Furthermore, unlike pyrethroids, the action of pyrethrins neither depend on nor were enhanced by repeated channel activation. We created a NavMs-based model of the cockroach sodium channel, in which pyrethrin II was docked at the pyrethroid receptor site 1 (PyR1), and proposed a rationale for the observed structure-activity relationship of the six pyrethrins. Our study sheds light on the molecular mechanism of pyrethrum action on sodium channels and reveled differences in the modes of action of the six bioactive constitutes of pyrethrum.

Whole-Life-Stage Characterization in the Basic Biology of Daphnia magna and Effects of TDCIPP on Growth, Reproduction, Survival, and Transcription of Genes.

Toxicity tests of chemicals have mainly focused on the partial life-cycle evaluation of model animals. Limited information is available for the evaluation of effects of chemicals from a whole-life-stage exposure perspective. The objective of this study was to perform a whole-life-stage characterization in the basic biology of Daphnia magna (D. magna) and evaluate the effects of a known organophosphate ester (OPE) contaminant, tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), on growth, reproduction, survival, and transcription of genes. The whole-life-stage characterization in growth, reproduction, and survival of D. magna was conducted, and representative sampling time points for the three developmental stages were identified (day 6, day 32, and day 62). Transcriptomic profiles for these three stages were compared, and stage-specific PCR arrays of D. magna were developed. The whole-life-stage exposure to environmentally relevant or greater concentrations of TDCIPP significantly inhibited growth and reproduction of D. magna and decreased survival at the later stage of the exposure experiment (≥32 days). Such adverse effects were not observed in the early stage of the exposure (<32 days), suggesting that short-term toxicity tests, such as the standard 21-day test, might underestimate the environmental risk of TDCIPP. Furthermore, expressions of genes selected at day 6, day 32, and day 62 were significantly changed after TDCIPP exposure, and the changes in the expressions of partial genes were correlated to the inhibitory effects on growth, reproduction, and survival.

Determination of a broad spectrum of endocrine-disrupting pesticides in fish samples by UHPLC-MS/MS using the pass-through cleanup approach.

We describe a new methodology for the simultaneous determination of the endocrine-disrupting herbicides (acetochlor, alachlor, amitrole, and atrazine), fungicides (carbendazim, triadimefon, penconazole, and propiconazole), and insecticides (carbaryl and carbofuran) in fish samples followed by high-performance liquid chromatography with tandem mass spectrometry. Samples were extracted and purified using the pass-through cleanup approach. The recoveries of the pesticides were in the range 71.8-116.5%, with relative standard deviations lower than 15.28%. Limits of quantitation were in the range of 0.03-2.50 µg/kg. Validation results on linearity, accuracy, and precision, as well as on application to the analysis of the endocrine-disrupting pesticides in 20 fish samples, demonstrated the applicability to screen the presence of pesticides in fish.

Effects of Pesticide Mixtures on Zooplankton Assemblages in Aquatic Microcosms Simulating Rice Paddy Fields.

The individual and combined effects of pesticides (chlorpyrifos, triadimefon and butachlor) on the zooplankton assemblages of microcosms were investigated. Laboratory microcosms were constructed with water and sediment to simulate aquatic conditions in China's rice paddy fields. Results from principal response curves analysis showed that butachlor and triadimefon had no significant impact individually on the population level in zooplankton assemblages. The deleterious effects of pesticide mixtures on the zooplankton were mainly caused by chlorpyrifos. In fact, assemblage succession only occurred in the treatments containing chlorpyrifos. There was no synergy effect on the microcosm from combinations of pesticides on the assemblages. The zooplankton assemblages affected by chlorpyrifos did not recover at the termination of the experiment, i.e., after 56 days.