Evaluation of boscalid toxicity on Daphnia magna by using antioxidant enzyme activities, the expression of genes related to antioxidant and detoxification systems, and life-history parameters

Development of a Portable Cell-Based Biosensor for the Ultra-Rapid Screening for Boscalid Residues in Lettuce

Fungal plant pathogens have posed a significant threat to crop production. However, the large-scale application of pesticides is associated with possible risks for human health and the environment. Boscalid is a widely used fungicide, consistently implemented for the management of significant plant pathogens. Conventionally, the detection and determination of boscalid residues is based on chromatographic separations. In the present study, a Bioelectric Recognition Assay (BERA)-based experimental approach combined with MIME technology was used, where changes in the electric properties of the membrane-engineering cells with anti-boscalid antibodies were recorded in response to the presence of boscalid at different concentrations based on the maximum residue level (MRL) for lettuce. The membrane-engineering Vero cells with 0.5 μg/mL of antibody in their surface were selected as the best cell line in combination with the lowest antibody concentration. Furthermore, the biosensor was tested against another fungicide in order to prove its selectivity. Finally, the BERA cell-based biosensor was able to detect the boscalid residue, below and above the MRL, in spiked lettuce leaf extracts in an entirely distinct and reproducible manner. This study indicates that the BERA-based biosensor, after further development and optimization, could be used for the routine, high-throughput detection of boscalid residue in lettuce, and not only that.

Cardiac and neurobehavioral impairments in three phylogenetically distant aquatic model organisms exposed to environmentally relevant concentrations of boscalid

Boscalid (2-Chloro-N-(4'-chlorobiphenyl-2-yl) nicotinamide), a pyridine carboxamide fungicide, is an inhibitor of the complex II of the respiration chain in fungal mitochondria. As boscalid is only moderately toxic for aquatic organisms (LC50 > 1-10 mg/L), current environmental levels of this compound in aquatic ecosystems, in the range of ng/L-μg/L, are considered safe for aquatic organisms. In this study, we have exposed zebrafish (Danio rerio), Japanese medaka (Oryzias latipes) and Daphnia magna to a range of concentrations of boscalid (1-1000 μg/L) for 24 h, and the effects on heart rate (HR), basal locomotor activity (BLA), visual motor response (VMR), startle response (SR), and habituation (HB) to a series of vibrational or light stimuli have been evaluated. Moreover, changes in the profile of the main neurotransmitters have been determined. Boscalid altered HR in a concentration-dependent manner, leading to a positive or negative chronotropic effect in fish and D. magna, respectively. While boscalid decreased BLA and increased VMR in Daphnia, these behaviors were not altered in fish. For SR and HB, the response was more species- and concentration-specific, with Daphnia exhibiting the highest sensitivity. At the neurotransmission level, boscalid exposure decreased the levels of L-aspartic acid in fish larvae and increased the levels of dopaminergic metabolites in D. magna. Our study demonstrates that exposure to environmental levels of boscalid alters cardiac activity, impairs ecologically relevant behaviors, and leads to changes in different neurotransmitter systems in phylogenetically distinct vertebrate and invertebrate models. Thus, the results presented emphasize the need to review the current regulation of this fungicide.

Pyriproxyfen Contamination in Daphnia magna: Identifying Early Warning Biomarkers

Pyriproxyfen is an insecticide currently employed in numerous countries for the management of agricultural and indoor pests. Several studies indicate that this insecticide has been detected in multiple rivers, with concentrations reaching as high as 99.59 ng/L in the Júcar River in Spain. Therefore, the determination of some biochemical and genetic effects of this insecticide on aquatic organisms could serve as an early warning mechanism to identify potential disruptions in various biomarkers. Based on this, Daphnia magna organisms were exposed to pyriproxyfen sublethal concentrations for 21 days. Some biochemical parameters, including cholesterol, triglycerides, glucose, lactate, and LDH activity, were determined. Additionally, some genetic biomarkers associated with oxidative stress, heat shock proteins, lipid metabolism, hemoglobin, metallothioneins, and vitellogenin synthesis were evaluated in daphnids exposed to the insecticide for 21 days. LDH activity increased significantly in those daphnids exposed to the highest insecticide concentration (14.02 µg/L), while cholesterol levels decreased significantly. In contrast, glucose, total proteins, and triglycerides remained unaffected in D. magna exposed to pyriproxyfen. On the other hand, exposure to the insecticide led to notable alterations in gene expression among individuals. Specifically, genes associated with lipid metabolism and reproduction exhibited a significant reduction in gene expression. Fabd expression was decreased by approximately 20% in exposed daphnids, while vtg expression was suppressed as much as 80% when compared to control values. Furthermore, it was observed that the hgb1 and hgb2 genes, associated with hemoglobin synthesis, exhibited significant overexpression. Notably, the dysfunction observed in both hemoglobin genes was linked to an increase in pigmentation in Daphnia magna during the course of the experiment. These alterations in gene expression could serve as effective indicators of early contamination even at low pesticide concentrations.

Selected Fungicides as Potential EDC Estrogenic Micropollutants in the Environment

An increasing level of pesticide exposition is being observed as a result of the consumption of large amounts of fruits, vegetables and grain products, which are key components of the vegetarian diet. Fungicides have been classified as endocrine-disrupting compounds, but their mechanisms of action have not yet been clarified. The effect of boscalid (B), cyprodinil (C) and iprodione (I) combined with Tamoxifen (T) and 17β-estradiol (E2) on cell viability, cell proliferation, reporter gene expression, ROS content, the cell membrane's function, cell morphology and antioxidant enzymes gene expression in MCF-7 and T47D-KBluc cell lines were investigated. The cell lines were chosen due to their response to 17β -estradiol. The selected fungicides are commonly used in Poland to protect crops against fungi. Our results revealed that the studied fungicides caused significant increases in cell viability and proliferation, and estrogenic activity was present in all studied compounds depending on their concentrations. Oxidative stress activated uncontrolled cancer cell proliferation by inducing ROS production and by inhibiting antioxidant defense. Our findings verify that the studied fungicides could possibly exhibit endocrine-disrupting properties and exposure should be avoided.

Evaluation of three novel soil bacterial strains for efficient biodegradation of persistent boscalid fungicide: Kinetics and identification of microbial biodegradation intermediates

Boscalid, a new fungicide of anilide group, is intended to prevent and treat grey mould (Botrytis cinerea), primarily in vines and other fruit plants. In many regions, its long half-life in soil and water poses a serious environmental threat. Boscalid is reported to be toxic to a variety of aquatic organisms. One of the best ways to lessen the amount of boscalid that gets into surface and ground waters is to reduce its concentration in soil. Soil microbes are crucial for the degradation of organic pollutants including pesticides. The present study reports the assessment of three novel soil bacterial strains isolated from pesticide-contaminated soil of Crop research centre, Pantnagar, Uttarakhand, India, which possess boscalid degradation ability. Two of these bacterial isolates could degrade boscalid up to 85-95% within 36 h of incubation period under shaking conditions in the minimal medium. The growth pattern of degrading bacterial isolates was monitored by recording the optical density (OD) of bacterial suspension using an ultra violet (UV)-visible spectrophotometer, whereas the concentration of primary boscalid was recorded by High-Performance Liquid Chromatography (HPLC-UV). A linear relationship was observed between the bacterial growth and the decrease in the residual concentration of boscalid. The concentration of boscalid during incubation with different bacterial strains could be best predicted by a second-order polynomial relationship with time and OD of the suspension as independent variables. Three degradation intermediates of boscalid namely, N-(1,1'-biphenyl-2-yl)pyridine-3-carboxamide (C₁₈H₁₄N₂O, N-{[1,1'-biphenyl]-2-yl}-2-chloropyridine-3-carboxamide (C₁₈H₁₃N₂OCl), and N-{[4'-chloro-1,1'-biphenyl]-2-yl}-2-chloropyridine ({C₁₇H₁₁NCl₂}OH) were identified by the liquid chromatography-mass spectrometry (LC-MS) analysis of biodegraded samples. The biodegradation of boscalid through bacterial isolates seemed to be an economical and eco-friendly method for degrading a highly persistent boscalid fungicide.

Evaluation of acute toxicity response to the algae Chlorella pyrenoidosa of biosynthetic silver nanoparticles catalysts

Biosynthetic of silver nanoparticles (AgNPs) by using fungi has attracted much attention due to its high catalytic efficiency and environmentally friendly characteristic. However, a few studies have focused on the ecological toxicity effects of biogenic AgNPs on algae. Here, we first investigated the catalytic reduction of 4-nitrophenol (4-NP) by WZ07-AgNPs biosynthesized by Letendraea sp. WZ07. WZ07-AgNPs had significant catalytic activity with 97.08% degradation of 4-NP in 3.5 min. Then, the toxic effects of WZ07-AgNPs and commercial-AgNPs were compared by Chlorella pyrenoidosa growth, chlorophyll content, protein content, physiological, and biochemical indexes. The results demonstrated that the algal cell biomass of C. pyrenoidosa was differentially inhibited after exposure to different concentrations of AgNPs, which showed concentration dependence and time dependence. The 96h-EC₅₀ values of WZ07-AgNPs and commercial-AgNPs on C. pyrenoidosa were 15.99 mg/mL and 12.69 mg/mL, respectively. With the increase concentration of AgNPs, the chlorophyll content was gradually decreased, the protein content was first increased and then decreased, the activities of superoxide dismutase (SOD) and catalase (CAT) were decreased, and the level of malondialdehyde (MDA) was increased significantly of C. pyrenoidosa. In general, AgNPs affect the growth of algae to some extent. However, compared with commercial-AgNPs, WZ07-AgNPs is less toxic to C. pyrenoidosa, which could be used as a potential and an eco-friendly catalyst. This study provides a basis for the safe application of biosynthetic AgNPs.

Chronic toxicity of diclofenac, carbamazepine and their mixture to Daphnia magna: a comparative two-generational study

The chronic toxicity of diclofenac (DCF) and carbamazepine (CBZ) as separate substances and in conjunction with their mixture on Daphnia magna was assessed in the parental (F0) and first filial (F1) generations. The second (F1-B2) and fifth (F1-B5) broods of F1 offspring were investigated and compared. Both drugs and their mixture were exposed to each generation of Daphnia magna for 21 days with life history, behavioural and gene expressions as measured endpoints. After the parental exposure, offspring from these two broods were transferred to a clean medium for a 21-day recovery. Exposure to diclofenac, carbamazepine and their mixture significantly inhibited growth, reproduction, swimming activities, heart rate, thoracic limb activities, reproductive and antioxidant-related genes in the parental as well as the first filial generations. These effects were relatively greater in the F1 generation. This indicates that Daphnia magna's sensitivity improved while its fitness declined over the two generations, which is an indicator of greater energy requirements for maintenance. Besides, the significant inhibition in the antioxidant-related genes implies that oxidative stress occurred in Daphnia magna under the exposure to these drugs. The significant reduction in the reproductive output, moulting frequency and cyp314 gene expression as a result of exposure to CBZ simultaneously obtained herein may indicate that this drug could act as an endocrine disruptor. Most of these significant effects were not recoverable after the 21-day recovery period. The findings reported herein highlight the necessity to include maternal effects in environmental risk assessment processes, considering that pollutant effects are underestimated during single-generational exposure.

Effects of Two Antiretroviral Drugs on the Crustacean Daphnia magna in River Water

Antiretroviral (ARVs) drugs are used to manage the human immunodeficiency virus (HIV) disease and are increasingly being detected in the aquatic environment. However, little is known about their effects on non-target aquatic organisms. Here, Daphnia magna neonates were exposed to Efavirenz (EFV) and Tenofovir (TFV) ARVs at 62.5–1000 µg/L for 48 h in river water. The endpoints assessed were mortality, immobilization, and biochemical biomarkers (catalase (CAT), glutathione S-transferase (GST), and malondialdehyde (MDA)). No mortality was observed over 48 h. Concentration- and time-dependent immobilization was observed for both ARVs only at 250–1000 µg/L after 48 h, with significant immobilization observed for EFV compared to TFV. Results for biochemical responses demonstrated that both ARVs induced significant changes in CAT and GST activities, and MDA levels, with effects higher for EFV compared to TFV. Biochemical responses were indicative of oxidative stress alterations. Hence, both ARVs could potentially be toxic to D. magna.

The research progress in and perspective of potential fungicides: Succinate dehydrogenase inhibitors

Succinate dehydrogenase inhibitors (SDHIs) have become one of the fastest growing classes of new fungicides since entering the market, and have attracted increasing attention as a result of their unique structure, high activity and broad fungicidal spectrum. The mechanism of SDHIs is to inhibit the activity of succinate dehydrogenase, thereby affecting mitochondrial respiration and ultimately killing pathogenic fungi. At present, they have become popular varieties researched and developed by major pesticide companies in the world. In the review, we focused on the mechanism, the history, the representative varieties, structure-activity relationship and resistance of SDHIs. Finally, the potential directions for the development of SDHIs were discussed. It is hoped that this review can strengthen the individuals' understanding of SDHIs and provide some inspiration for the development of new fungicides.

Evaluation of the Acute Effects and Oxidative Stress Responses of Phenicol Antibiotics and Suspended Particles in Daphnia magna

Suspended particles (SP) exist widely in various water systems and are able to adsorb other pollutants in water, producing ecotoxic effects on aquatic nontarget species. Until now, however, few studies have focused on the effects of SP on antibiotics. Therefore, the present study investigated the effects of the mixtures of SP and phenicol antibiotics (chloramphenicol [CAP], thiamphenicol [TAP]) on acute toxicity and oxidative stress responses in Daphnia magna. The results indicated that the acute toxicity of phenicol antibiotics in D. magna was increased when combined with SP. Besides, the immobilization of daphnids caused by phenicol drugs in the presence of 10 mg/L of SP was more intense than that with 200 mg/L of SP. Furthermore, the impact of SP with diverse concentrations on the activity of catalase and the level of reduced glutathione in D. magna was different. Notably, almost all CAP + TAP + SP treatments markedly increased malondialdehyde content in D. magna, causing potential cellular oxidative damage in D. magna. In summary, the present study provides insights into the toxic effects of phenicol antibiotic and SP mixtures on aquatic organisms. Environ Toxicol Chem 2021;40:2463-2473. © 2021 SETAC.

Exposure to Boscalid Induces Reproductive Toxicity of Zebrafish by Gender-Specific Alterations in Steroidogenesis

Boscalid is a succinate dehydrogenase inhibitor fungicide and is frequently detected in surface water. Due to the frequent detection of boscalid, we evaluated its impact on the reproduction of adult zebrafish following a 21 d exposure to 0, 0.01, 0.1, and 1.0 mg/L. Following exposure to boscalid, the fertility of female zebrafish and fertilization rate of spawning eggs were reduced in a concentration-dependent manner up to a respective 87% and 20% in the highest concentration. A significant 16% reduction in the percentage of late vitellogenic oocytes was noted in ovaries, and a significant 74% reduction in the percentage of spermatids in testis was also observed after treatment with 1.0 mg/L. 17β-Estradiol (E2) concentrations decreased significantly in females (34% decrease) but significantly increased in males (15% increase) following 1.0 mg/L boscalid treatment. The expression of genes (such as era, er2b, cyp19a, and cyp19b) related to the hypothalamus-pituitary-gonad-liver (HPGL) axis was significantly altered and positively correlated with E2 concentrations in female and male zebrafish (p < 0.05). Molecular docking results revealed that the binding modes between boscalid and target proteins (ER and CYP19) of zebrafish were similar to that of the reference compounds and the target proteins. The binding energies indicate that boscalid may have a weak estrogen-like binding effect or CYP19 inhibition, potentially altering the HPGL axis, thereby reducing E2 concentrations and fecundity in females. In contrast, boscalid caused significant induction of E2 steroidogenesis and subsequent feminization of gonads in males, indicating gender-specific adverse outcome pathways.