Photolysis of dinotefuran and nitenpyram in water and ice phase: Influence mechanism of temperature over photolysis.

Neonicotinoids are widely used pesticides around the world, but the photolysis of neonicotinoids in cold agricultural region are still in blank. This paper aimed to study the influence of cold temperature over photolysis of neonicotinoids. To this end, the photolysis rates and photoproducts of dinotefuran and nitenpyram in water, ice and freeze-thawing condition were determined.

Photolysis and photo-enhanced toxicity of three novel designed neonicotinoids: Impact of novel modifying groups.

Three novel neonicotinoids (cycloxaprid, flupyradifurone and sulfoxaflor) were designed to reduce the biotoxicity for non-target organisms. These neonicotinoids were photolyzed under light radiation, but it was unclear for the photo-enhanced toxicity and influences of the novel modifying group of the three neonicotinoids. The photolysis and photo-enhanced toxicity experiments were performed for the three neonicotinoids, coupled with quantum chemistry calculation, the mechanisms of photolysis, photo-enhanced toxicity and the influences of novel modifying groups were analyzed.

Relationship between photolysis mechanism and photo-enhanced toxicity to Vibrio Fischeri for neonicotinoids with cyano-amidine and nitroguanidine structures.

Neonicotinoids are widely used pesticides that contaminate aquatic environments. Although these chemicals can be photolyzed under sunlight radiation, it is unclear for the relationship between photolysis mechanism and toxicity change in aquatic organisms. This study aims to determine the photo-enhanced toxicity of four neonicotinoids with different main structures (acetamiprid, and thiacloprid for cyano-amidine structure, imidacloprid and imidaclothiz for nitroguanidine).

Assessment of toxic mechanisms and mode of action to three different levels of species for 14 antibiotics based on interspecies correlation, excess toxicity, and QSAR.

Antibiotics have received much attention owing to their ecotoxicity toward nontarget aquatic creatures. However, the mode of action (MOA) of toxicity against nontarget organisms is unclear in some aquatic organisms. In this study, the comparison of toxicities through interspecies correlations, excess toxicity calculated from toxicity ratio, and quantitative structure-activity relationship (QSAR) was carried out to investigate the MOAs for 14 antibiotics among Daphnia magna, Vibrio fischeri, and Pseudokirchneriella subcapitata.

Comparison of modes of action between fish, cell and mitochondrial toxicity based on toxicity correlation, excess toxicity and QSAR for class-based compounds.

Mitochondria are significant targets in cells for many environmental chemicals. Mitochondrial damage and dysfunction can lead to apoptosis and death of fish. The objectives of this study were to compare the modes of action (MOAs) between fish, cell and mitochondrial toxicity.

Comparison of modes of toxic action between Rana chensinensis tadpoles and Limnodrilus hoffmeisteri worms based on interspecies correlation, excess toxicity and QSAR for class-based compounds.

Insecticides, fungicides, dinitrobenzenes, resorcinols, phenols and anilines are widely used in agricultural and industrial productions. However, their modes of toxic action are unclear in some nontarget organisms, such as worms and tadpoles. In this study, acute toxicity data was experimentally collected for Limnodrilus hoffmeisteri worms and Rana chensinensis tadpoles, respectively.

Assessing sub-lethal effects of the dinitroaniline herbicide pendimethalin in zebrafish embryos/larvae (Danio rerio).

Pendimethalin is a dinitroaniline herbicide used to control broadleaf weeds by inhibiting the formation of microtubules during cell division. Its use on a variety of crops leads to its potential entry into aquatic environments, but little is known about its sub-lethal toxicity to early developmental stages of aquatic vertebrates. To address this knowledge gap, we assessed the toxicity of pendimethalin to zebrafish embryos and larvae by measuring mortality, developmental abnormalities, oxidative respiration, reactive oxygen species, gene expression, and locomotor activity following exposure to the herbicide throughout early development.

Exposure to acetochlor impairs swim bladder formation, induces heat shock protein expression, and promotes locomotor activity in zebrafish (Danio rerio) larvae.

Acetochlor is one of the most widely used herbicides in the world, however, there are few data on the sub-lethal effects of acetochlor on early developmental stages of fish. To address this, we measured survival, deformity, swim bladder formation, embryo oxygen consumption rates, reactive oxygen species (ROS) levels, transcripts (related to swim bladder formation, oxidative damage response, and apoptosis) and behavior responses following exposure to acetochlor (0.001 µM up to 125 µM).

Behavioral and developmental toxicity assessment of the strobilurin fungicide fenamidone in zebrafish embryos/larvae (Danio rerio).

Strobilurin fungicides are among the most widely used in the world and have characteristics that include high water solubility and toxicity to aquatic organisms. While several studies report on mechanisms of toxicity of strobilurins in fish, there are no data on the sub-lethal toxicity of fish to the fungicide fenamidone. To address this gap, survival and hatch rate, deformities, mitochondrial bioenergetics, expression of oxidative stress and apoptotic genes, and behavior (locomotor activity and anxiolytic-related behaviors) were assessed in zebrafish embryos and larvae following exposure to fenamidone.

Bio-uptake, tissue distribution and metabolism of a neonicotinoid insecticide clothianidin in zebrafish.

Neonicotinoids have been often detected in aquatic environment with high concentrations; however, little is known about their risk and fate to/in fish. This study systematically investigated the bio-uptake, tissue distribution and metabolism of neonicotinoids in zebrafish, taking clothianidin (CLO) as an example. The results revealed the uptake and elimination kinetics of CLO in whole fish and different tissues was very similar, and its bioconcentration factor (<1) indicates the low bioaccumulation potential in zebrafish.

Comparative analysis on the photolysis kinetics of four neonicotinoid pesticides and their photo-induced toxicity to Vibrio Fischeri: Pathway and toxic mechanism.

Neonicotinoids are widely used pesticides all over the world and pose severe water pollution. Although they can be degraded via absorbing sunlight, few attentions have been paid to the environmental risks of their photolysis products. In this paper, the photo-toxicity was investigated for four neonicotinoids (dinotefuran, nitenpyram, thiamethoxam and clothianidin) based on a series of experiments (i.

Discrimination of active and inactive substances in cytotoxicity based on Tox21 10K compound library: Structure alert and mode of action.

In vitro cytotoxicity assay is an ideal alternative method for the in vivo toxicity in the risk assessment of pollutants in environment. However, modes of action (MOAs) of cytotoxicity have not been investigated for a wide range of compounds. In this paper, binomial and recursive partitioning analysis were carried out between the cytotoxicity and molecular descriptors for 8981 compounds.

Freshwater quality criteria of four strobilurin fungicides: Interspecies correlation and toxic mechanism.

Strobilurin fungicides are widely used pesticides in the world. They can have toxic effects not only to target organisms, but also to nontarget organisms. To assess their ecological risk, species sensitivity distributions (SSDs) are required for the development of water quality criteria (WQC).

Identification of active and inactive agonists/antagonists of estrogen receptor based on Tox21 10K compound library: Binomial analysis and structure alert.

Endocrine disrupting chemicals can mimic, block, or interfere with hormones in organisms and subsequently affect their development and reproduction, which has raised significant public concern over the past several decades. To investigate (quantitative) structure-activity relationship, 8280 compounds were compiled from the Tox21 10K compound library. The results show that 50% activity concentrations of agonists are poorly related to that of antagonists because many compounds have considerably different activity concentrations between the agonists and antagonists.

Relative comparison of strobilurin fungicides at environmental levels: Focus on mitochondrial function and larval activity in early staged zebrafish (Danio rerio).

Strobilurin fungicides are used globally and have been detected in microgram per liter concentrations in aquatic environments. Here, we determined the potential toxicity of four commonly used strobilurins (azoxystrobin, kresoxim-methyl, pyraclostrobin, trifloxystrobin) on mitochondrial function and locomotor activity of larval zebrafish at an environmentally relevant level. As the mode of action of strobilurins in fungi is binding to cytochrome bc1 in mitochondrial complex III, we evaluated exposure effects on mitochondrial oxidative phosphorylation of zebrafish, by measuring oxygen consumption rates, mitochondria-related enzyme activities, and transcripts levels for genes associated with the electron transfer chain and citric acid cycle.

Evaluation of modes of action of pesticides to Daphnia magna based on QSAR, excess toxicity and critical body residues.

Agricultural pesticides serve as effective controls of unwanted weeds and pests. However, these same chemicals can exert toxic effects in non-target organisms. To determine chemical modes of action, the toxicity ratio (TR) and critical body residues (CBRs) of 57 pesticides were calculated for Daphnia magna.

Photolysis and photo-induced toxicity of pyraclostrobin to Vibrio fischeri: Pathway and toxic mechanism.

Pyraclostrobin is a fungicide used widely across the world. However, its photolysis pathway and toxic mechanism is unclear. In this study, photolysis and photo-induced toxicity of pyraclostrobin to Vibrio fischeri were determined.

Comparison of modes of action among different trophic levels of aquatic organisms for pesticides and medications based on interspecies correlations and excess toxicity: Theoretical consideration.

Pesticides and medications have adverse effects in non-target organisms that can lead to different modes of action (MOAs). However, no study has been performed to compare the MOAs between different levels of aquatic species. In this study, theoretical equations of interspecies relationship and excess toxicity have been developed and used to investigate the MOAs among fish, Daphnia magna, Tetrahymena pyriformis and Vibrio fischeri for pesticides and medications.

Theoretical consideration on the prediction of in vivo toxicity from in vitro toxicity: Effect of bio-uptake equilibrium, kinetics and mode of action.

Although in vitro assay is an ideal alternative method for the in vivo toxicity prediction, different in vivo-in vitro correlations have been observed for the toxicity endpoints obtained from different levels of species. In this paper, theoretical in vivo-in vitro toxicity correlations have been developed for cytotoxicity versus human, mammalian and fish toxicity, respectively. These theoretical models were then used to investigate the correlations and the influencing factors between in vivo and in vitro toxicity.

Toxicity of some prevalent organic chemicals to tadpoles and comparison with toxicity to fish based on mode of toxic action.

Although mode of action (MOA) plays a key role in the understanding of the toxic mechanism of chemicals, the MOAs of class-based compounds to tadpoles have not been investigated. To explore the MOAs, acute toxicity (expressed as log 1/LC) to Rana chensinensis tadpoles were determined and molecular descriptors were calculated. Quantitative structure-activity relationship (QSAR) showed that toxicity to tadpoles is closely related to the chemical octanol/water partition coefficient (log K), energy of the lowest unoccupied molecular orbital (E), and number of hydrogen bond donors and acceptors (NH), representing the bio-uptake potential in tadpoles, the electrophilicity and hydrogen bonding capacity with target site(s), respectively.

Comparison of modes of action between fish and zebrafish embryo toxicity for baseline, less inert, reactive and specifically-acting compounds.

The mode of action (MOA) plays a key role in the risk assessment of pollutants in water. Although fish is a key model organism used in the risk assessment of pollutants in water, the MOAs have not been compared between fish and embryo toxicity for classified compounds. In this paper, regression analysis was carried out for fish and embryo toxicities against the calculated molecular descriptors and MOAs were evaluated from toxicity ratio.

Fluazinam impairs oxidative phosphorylation and induces hyper/hypo-activity in a dose specific manner in zebrafish larvae.

Fluazinam is a pyridinamine fungicide that induces oxidative stress and mitochondrial damage in cells, and it has been reported to be neurotoxic. To characterize the biological effects of fluazinam, we assessed mitochondrial bioenergetics, dopamine system expression, and behavior of early life staged zebrafish (0.01 μM-0.

High-throughput assessment of oxidative respiration in fish embryos: Advancing adverse outcome pathways for mitochondrial dysfunction.

Mitochondrial dysfunction is a prevalent molecular event that can result in multiple adverse outcomes. Recently, a novel high throughput method to assess metabolic capacity in fish embryos following exposure to chemicals has been adapted for environmental toxicology. Assessments of oxygen consumption rates using the Seahorse XF(e) 24/96 Extracellular Flux Analyzer (Agilent Technologies) can be used to garner insight into toxicant effects at early stages of development.

Development of thresholds of excess toxicity for environmental species and their application to identification of modes of acute toxic action.

The acute toxicity of organic pollutants to fish, Daphnia magna, Tetrahymena pyriformis, and Vibrio fischeri was investigated. The results indicated that the Toxicity Ratio (TR) threshold of log TR =1, which has been based on the distribution of toxicity data to fish, can also be used to discriminate reactive or specifically acting compounds from baseline narcotics for Daphnia magna and Vibrio fischeri. A log TR=0.

Mitochondrial bioenergetics and locomotor activity are altered in zebrafish (Danio rerio) after exposure to the bipyridylium herbicide diquat.

Diquat is a non-selective bipyridylium herbicide which has replaced its sister compound paraquat, as paraquat is associated to an increased risk for Parkinson's disease. However, the propensity of diquat to propagate reactive oxygen species ensures that diquat remains an exposure risk in non-target organisms. In this study, zebrafish (Danio rerio) embryos were exposed to diquat (1, 10, 100μM) beginning at ∼6h post fertilization for up to 7days to learn more about the mechanisms underlying diquat toxicity during vertebrate development.