Under laboratory conditions, the effects of thiamethoxam were investigated in larvae, pupae and emerging honey bees after exposure at larval stages with different concentrations in the food (0.00001 ng/µL, 0.001 ng/µL and 1.44 ng/µL). Thiamethoxam reduced the survival of larvae and pupae and consequently decreased the percentage of emerging honey bees. Thiamethoxam induced important physiological disturbances. It increased acetylcholinesterase (AChE) activity at all developmental stages and increased glutathione-S-transferase (GST) and carboxylesterase para (CaEp) activities at the pupal stages. For midgut alkaline phosphatase (ALP), no activity was detected in pupae stages, and no effect was observed in larvae and emerging bees. We assume that the effects of thiamethoxam on the survival, emergence and physiology of honey bees may affect the development of the colony. These results showed that attention should be paid to the exposure to pesticides during the developmental stages ofthe honey bee. This study represents the first investigation of the effects of thiamethoxam on the development of A. mellifera following larval exposure.

International audience | The study was prompted to characterize the B-type esterase activities in the terrestrial snail <em>Xeropicta derbentina</em> and to evaluate its sensitivity to organophosphorus and carbamate pesticides. Specific cholinesterase and carboxylesterase activities were mainly obtained with acetylthiocholine (Km =77.2 mM; Vmax= 38.2 mU/mg protein) and 1-naphthyl acetate (Km= 222 mM, Vmax= 1095 mU/mg protein) substrates, respectively. Acetylcholinesterase activity was concentration-dependently inhibited by chlorpyrifos-oxon, dichlorvos, carbaryl and carbofuran (IC50 =1.35 x 105–3.80 x 108 M). The organophosphate-inhibited acetylcholinesterase activity was reactivated in the presence of pyridine-2- aldoxime methochloride. Carboxylesterase activity was inhibited by organophosphorus insecticides (IC50 =1.20 x 105–2.98 x 108 M) but not by carbamates. B-esterase-specific differences in the inhibition by organophosphates and carbamates are discussed with respect to the buffering capacity of the carboxylesterase to reduce pesticide toxicity. These results suggest that B-type esterases in<em> X. derbentina</em> are suitable biomarkers of pesticide exposure and that this snail could be used as sentinel species in field monitoring of Mediterranean climate regions

The use of reclaimed water in agriculture represents a promising alternative to relieve pressure on freshwater supplies, especially in arid or semiarid regions facing water scarcity. However, this implies introducing micropollutants such as pharmaceutical residues into the environment. The fate and the ecotoxicological impact of valsartan, an antihypertensive drug frequently detected in wastewater effluents, were evaluated in soil-earthworm microcosms. Valsartan dissipation in the soil was concomitant with valsartan acid formation. Although both valsartan and valsartan acid accumulated in earthworms, no effect was observed on biomarkers of exposure (acetylcholinesterase, glutathione S-transferase and carboxylesterase activities). The geometric mean index of soil enzyme activity increased in the soils containing earthworms, regardless of the presence of valsartan. Therefore, earthworms increased soil carboxylesterase, dehydrogenase, alkaline phosphatase, β-glucosidase, urease and protease activities. Although bacterial richness significantly decreased following valsartan exposure, this trend was enhanced in the presence of earthworms with a significant impact on both alpha and beta microbial diversity. The operational taxonomic units involved in these changes were related to four (Proteobacteria, Bacteroidetes, Actinobacteria and Firmicutes) of the eight most abundant phyla. Their relative abundances significantly increased in the valsartan-treated soils containing earthworms, suggesting the presence of potential valsartan degraders. The ecotoxicological effect of valsartan on microbes was strongly altered in the earthworm-added soils, hence the importance of considering synergistic effects of different soil organisms in the environmental risk assessment of pharmaceutical active compounds.

PFASs are highly persistent in both natural and living environment, and pose a significant risk for wildlife and human beings. The present study was carried out to determine the inhibitory behaviours of fourteen PFASs on metabolic activity of two major isoforms of carboxylesterases (CES). The probe substrates 2-(2-benzoyl-3-methoxyphenyl) benzothiazole (BMBT) for CES1 and fluorescein diacetate (FD) for CES2 were utilized to determine the inhibitory potentials of PFASs on CES in vitro. The results demonstrated that perfluorododecanoic acid (PFDoA), perfluorotetradecanoic acid (PFTA) and perfluorooctadecanoic acid (PFOcDA) strongly inhibited CES1 and CES2. The half inhibition concentration (IC₅₀) value of PFDoA, PFTA and PFOcDA for CES1 inhibition was 10.6 μM, 13.4 μM and 12.6 μM, respectively. The IC₅₀ for the inhibition of PFDoA, PFTA and PFOcDA towards CES2 were calculated to be 9.56 μM, 17.2 μM and 8.73 μM, respectively. PFDoA, PFTA and PFOcDA exhibited noncompetitive inhibition towards both CES1 and CES2. The inhibition kinetics parameters (Kᵢ) were 27.7 μM, 26.9 μM, 11.9 μM, 4.04 μM, 29.1 μM, 27.4 μM for PFDoA-CES1, PFTA-CES1, PFOcDA-CES1, PFDoA-CES2, PFTA-CES2, PFOcDA-CES2, respectively. In vitro-in vivo extrapolation (IVIVE) predicted that when the plasma concentrations of PFDoA, PFTA and PFOcDA were greater than 2.77 μM, 2.69 μM and 1.19 μM, respectively, it might interfere with the metabolic reaction catalyzed by CES1 in vivo; when the plasma concentrations of PFDoA, PFTA and PFOcDA were greater than 0.40 μM, 2.91 μM, 2.74 μM, it might interfere with the metabolic reaction catalyzed by CES2 in vivo. Molecular docking was used to explore the interactions between PFASs and CES. In conclusion, PFASs were found to cause inhibitory effects on CES in vitro, and this finding would provide an important experimental basis for further in vivo testing of PFASs focused on CES inhibition endpoints.

Under laboratory conditions, the effects of thiamethoxam were investigated in larvae, pupae and emerging honey bees after exposure at larval stages with different concentrations in the food (0.00001 ng/μL, 0.001 ng/μL and 1.44 ng/μL). Thiamethoxam reduced the survival of larvae and pupae and consequently decreased the percentage of emerging honey bees. Thiamethoxam induced important physiological disturbances. It increased acetylcholinesterase (AChE) activity at all developmental stages and increased glutathione-S-transferase (GST) and carboxylesterase para (CaEp) activities at the pupal stages. For midgut alkaline phosphatase (ALP), no activity was detected in pupae stages, and no effect was observed in larvae and emerging bees. We assume that the effects of thiamethoxam on the survival, emergence and physiology of honey bees may affect the development of the colony. These results showed that attention should be paid to the exposure to pesticides during the developmental stages of the honey bee. This study represents the first investigation of the effects of thiamethoxam on the development of A. mellifera following larval exposure.

Pyrethroids and metals were simultaneously detected in aquatic environment and showed antagonistic lethality to the benthic invertebrate, Chironomus dilutus. Accelerated biotransformation of pyrethroids in organism by the presence of metals was proposed as the likely reason for the antagonism. Mechanistic explanation for the role of toxicokinetics of pyrethroids in the antagonistic interaction would help better understanding the reasons for the joint toxicity. The goal was achieved in the current study by evaluating the impact of cadmium on toxicokinetic parameters of permethrin in C. dilutus, and by explaining the interaction through quantifying the activity and gene expression of biotransformation-related enzymes. Toxicokinetic parameters were simulated using a first-order kinetic model. Bioconcentration factors and uptake and elimination rate constants for permethrin were not significantly changed with the addition of cadmium at sublethal level, neither did the activity of enzymes, including glutathione S-transferase (GST), carboxylesterase (CarE), catalase and lipid peroxidation. Yet, the activities of metabolism-related enzymes (GST and CarE) showed an elevating tendency with adding cadmium. Furthermore, the expression of metabolism-related genes, including cytochrome P450 and glutathione S-transferase genes were significantly up-regulated in C. dilutus exposed to a mixture of permethrin and cadmium compared with permethrin only. Although co-exposure to cadmium did not induce toxicokinetic changes of permethrin in C. dilutus, it did enhance the activity of metabolic enzymes which were encoded by the metabolism-related genes, suggesting an acceleration of biotransformation of permethrin to less toxic metabolites in the midges. This possibly explained the antagonistic interaction for permethrin and cadmium.

Dinotefuran is a third-generation neonicotinoid pesticide and is increasingly used in agricultural production, which has adverse effects on nontarget organisms. However, the research on the impact of dinotefuran on nontarget organisms is still limited. Here the toxic effects of dinotefuran on an important economic species and a model lepidopteran insect, Bombyx mori, were investigated. Exposure to different doses of dinotefuran caused physiological disorders or death. Cytochrome P450, glutathione S-transferase, carboxylesterase, and UDP glycosyl-transferase activities were induced in the fat body at early stages after dinotefuran exposure. By contrast, only glutathione S-transferase activity was increased in the midgut. To overcome the lack of sensitivity of the biological assays at the individual organism level, RNA sequencing was performed to measure differential expressions of mRNA from silkworm larvae after dinotefuran exposure. Differential gene expression profiling revealed that various detoxification enzyme genes were significantly increased after dinotefuran exposure, which was consistent with the upregulation of the detoxifying enzyme. The global transcriptional pattern showed that the physiological responses induced by dinotefuran toxicity involved multiple cellular processes, including energy metabolism, oxidative stress, detoxification, and other fundamental physiological processes. Many metabolism processes, such as carbon metabolism, fatty acid biosynthesis, pyruvate metabolism, and the citrate cycle, were partially repressed in the midgut or fat body. Furthermore, dinotefuran significantly activated the MAPK/CREB, CncC/Keap1, PI3K/Akt, and Toll/IMD pathways. The links between physiological, biochemical toxicity and comparative transcriptomic analysis facilitated the systematic understanding of the integrated biological toxicity of dinotefuran. This study provides a holistic view of the toxicity and detoxification metabolism of dinotefuran in silkworm and other organisms.

A total of 164 blood samples from 16 clinically healthy bottlenose dolphins (Tursiops truncatus), were obtained from an aquarium in Spain between 2019 and 2020, as part of their preventive medicine protocol. In addition to conventional haematological and biochemical analyses, plasmatic B-esterase activities were characterised to determine the potential application of such analyses in wild counterparts. The hydrolysis rates for the substrates of acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) and carboxylesterase (CE) activity in plasma were measured, the last using two commercial substrates, p-nitrophenyl acetate (pNPA) and p-nitrophenyl butyrate (pNPB). Activity rates (mean ± SEM in nmol/min/mL plasma) were (in descending order): AChE (125.6 ± 3.8), pNPB-CE (65.0 ± 2.2), pNPA-CE (49.7 ± 1.1) and BuChE (12.8 ± 1.3). These values for dolphins are reported in here for the first time in this species. Additionally, the in vitro sensitivity of two B-esterases (AChE and pNPB-CE) to chemicals of environmental concern was determined, and the protective role of plasmatic albumin assessed. Out of the B-esterases measured in plasma of dolphin, AChE activity was more responsive in vitro to pesticides, while CEs had a low response to plastic additives, likely due to the protective presence of albumin. However, the clear in vitro interaction of these environmental chemicals with purified AChE from electric eels and recombinant human hCEs (hCE1 and hCE2) and albumin, predicts their impact in other tissues that require in vivo validation. A relationship between esterase-like activities and health parameters in terrestrial mammals has already been established. Thus, B-esterase measures could be easily included in marine mammal health assessment protocols for dolphins as well, once the relationship between these measures and the animal's fitness has been established.

Expansion of sugarcane crops may have contributed to the increased contamination of native habitats in Brazil. Several species of amphibians inhabit ponds formed in flooded farmlands, where pesticide concentrations are usually high. This study evaluated the ecotoxicological effects of the sugarcane pesticides fipronil and 2,4-D, as well as the fertilizer vinasse (isolated and mixed), on physiological responses of Leptodactylus fuscus and Lithobates catesbeianus tadpoles. In situ assays were conducted in mesocosms with concentrations based on the doses recommended by the manufacturer. Vinasse (1.3% dilution) caused 100% tadpoles’ mortality immediately after its application. Fipronil and/or 2,4-D altered antioxidant and biotransformation responses, induced neurotoxicity and changed lipid contents in tadpoles. A multivariate approach indicated that the mixture of pesticides induced most of the sublethal effects in both tadpole species, in addition to the isolated fipronil in L. fuscus. Fipronil alone increased glucose-6-phosphate dehydrogenase (G6PDH) activity, decreased acetylcholinesterase (AChE) and total lipid contents, and altered some individual lipid classes (e.g., free fatty acids and acetone-mobile polar lipids) in L. fuscus. The interaction between fipronil and 2,4-D in this species were more evident for lipid contents, although enzymatic alterations in G6PDH, AChE and glutathione-S-transferase (GST) were also observed. In L. catesbeianus, the mixture of pesticides reduced triglycerides and total lipids, as well as increased GST and decreased AChE activities. The detoxifying enzyme carboxylesterase was reduced by 2,4-D (alone or in mixture) in both species. Isolated pesticides also modulated specific lipid classes, suggesting their disruptive action on energy metabolism of tadpoles. Our study showed that fipronil, 2,4-D, and vinasse, individually or mixed, can be harmful to amphibians during their larval phase, causing mortality or impairing their functional responses.

Uptake and accumulation by plants is a significant pathway in the migration and transformation of phthalate esters (PAEs) in the environment. However, limited information is available on the mechanisms of PAE metabolism in plants. Here, we investigated the metabolism of di-n-butyl phthalate (DnBP), one of the most frequently detected PAEs, in pumpkin (Cucurbita moschata) seedlings via a series of hydroponic experiments with an initial concentration of 10 mg L⁻¹. DnBP hydrolysis occurred primarily in the root, and two of its metabolites, mono-n-butyl phthalate (MnBP) and phthalic acid (PA), were detected in all plant tissues. The MnBP concentration was an order of magnitude higher than that of PA in shoots, which indicated MnBP was more readily transported to the shoot than was PA because of the former's dual hydrophilic and lipophilic characteristics. More than 80% of MnBP and PA were located in the cell water-soluble component except that 96% of MnBP was distributed into the two solid cellular fractions (i.e., cell wall and organelles) at 96 h. A 13–20% and 29–54% increase of carboxylesterase (CXE) activity shown in time-dependent and concentration-dependent experiments, respectively, indicated the involvement of CXEs in plant metabolism of DnBP. The level of CXE activity in root subcellular fractions was in the order: the cell water-soluble component (88–94%) >> cell wall (3–7%) > cell organelles (3–4%), suggesting that the cell water-soluble component is the dominant locus of CXE activity and also the domain of CXE-catalyzed hydrolysis of DnBP. The addition of triphenyl phosphate, a CXE inhibitor, led to 43–56% inhibition of CXE activity and 16–25% increase of DnBP content, which demonstrated the involvement of CXEs in plant metabolism of DnBP. This study contributes to our understanding of enzymitic mechanisms of PAE transformation in plants.