Developmental toxicity of cypermethrin in embryo-larval stages of zebrafish

Synergistic toxic effects and mechanistic insights of beta-cypermethrin and pyraclostrobin exposure on hook snout carp (Opsariichthys bidens): A biochemical, transcriptional, and molecular approach

The extensive utilization of pesticides results in their frequent detection in aquatic environments, often as complex mixtures, posing risks to aquatic organisms. The hook snout carp (Opsariichthys bidens) serves as a valuable bioindicator for evaluating the impacts of environmental pollutants in aquatic ecosystems. However, few studies examined the toxic effects of pesticides on O.bidens, let alone the characterization of the combined effects resulting from their mixtures. This study aims to elucidate the toxic effects of beta-cypermethrin and pyraclostrobin on O.bidens, individually and in combination, focusing on biochemical, transcriptional, and molecular responses. By organizing and analyzing the toxicogenomic databases, both pesticides were identified as a contributor to processes such as apoptosis, oxidative stress, and inflammatory responses. The acute toxicity test revealed comparable acute toxicity of beta-cypermethrin and pyraclostrobin on O.bidens, with LC50 being 0.019 and 0.027 mg/L, respectively, whereas the LC50 decreased to 0.0057 and 0.0079 mg/L under the combined exposure, indicating potential synergistic effects. The activities of enzymes involved in oxidative stress and detoxification were significantly altered after exposure, with superoxide dismutase (SOD) and catalase (CAT) increasing, while malondialdehyde (MDA) levels decreased. The activity of CYP450s was significantly changed. Likewise, the expression levels of genes (mn-sod, p53, esr, il-8) associated with oxidative stress, apoptosis, endocrine and immune systems were significantly increased. Combined exposure to the pesticides significantly exacerbated the aforementioned biological processes in O.bidens. Furthermore, both pesticides can modify protein activity by binding to the surface of SOD molecules and altering protein conformation, contributing to the elevated enzyme activity. Through the investigation of the synergistic toxic effects of pesticides and molecular mechanisms in O.bidens, our findings highlight the importance of assessing the combined effects of pesticide mixtures in aquatic environments.

AhR agonists screening and identification in indoor dust based on non-target chemical analysis by GC-Q-TOFMS and biological effect evaluation referring to ToxCast/Tox21 database

Numerous studies reported the concentration of agonists of aryl hydrocarbon receptor (AhR) in indoor dust by target chemical analysis or the biological effects of activating the AhR by indoor extracts, but the major AhR agonists identification in indoor dust were rarely researched. In the present study, the indoor dust samples were collected for 7-ethoxyresorufin O-deethylase (EROD) assay and both non-targeted and targeted chemical analysis for AhR agonists by gas chromatography quadrupole time-of-flight mass spectrometry and gas chromatography-mass spectrometry analysis. Coupled with non-targeted analysis and toxicity Forecaster (ToxCast)/Tox21 database, 104 ToxCast chemicals were screened to be able to induce EROD response. The combination of targeted chemical analyses and biological effects evaluation indicated that PAHs, dibutyl phthalate (DBP) and Cypermethrin might be the important AhR-agonists in different indoor dust and mainly contributed in 1.84%-97.56 % (median: 26.62%) of total observed biological effects through comparing toxic equivalency quotient derived from chemical analysis with biological equivalences derived from bioassay. DBP and cypermethrin seldom reported in the analysis of AhR agonists should raise great concern. In addition, the present results in experiment of synthetic solution of 4 selected AhR-agonists pointed out that some unidentified AhR agonists existed in indoor dust.

Placental transcriptome variation associated with season, location, and urinary prenatal pyrethroid metabolites of Thai farm-working women

Prenatal exposure to pyrethroids is linked to adverse health effects in early life and proper placental function is critical to fetal development. This study explores the impact of prenatal pyrethroid exposure, as well as factors impacting exposure and effect, on the placental transcriptome, to understand pyrethroid exposures' relationship to placental function. The study of Asian Women and their Offspring's Development and Environmental Exposures (SAWASDEE) recruited pregnant farm-working women from two agricultural districts in the Chiang Mai province of Thailand between 2017 and 2019. This cohort was predominantly exposed to cypermethrin (type II), alongside pyrethroids such as cyfluthrin (type II) and permethrin (type I). In 253 participants, maternal urinary pyrethroid metabolites, 3-phenoxybenzoic acid (PBA), cis-3-(2,2-Dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (CDCCA), and trans-3-(2,2-Dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (TDCCA) were measured in early, middle, and late pregnancy and adjusted for urinary creatinine. The placental transcriptome was analyzed using RNA-Seq. Using generalized linear regression, we identified differentially expressed genes (DEGs) associated with the sum of each metabolite across pregnancy, as well as those associated with location of residence and season of birth. Pathway and upstream transcription factor analyses were performed to examine potential mechanisms associated with DEGs. Notably, TDCCA and CDCCA levels peaked in late pregnancy, with significant regional differences, particularly higher levels in the Fang region. Placental gene expression analysis showed no DEGs associated with individual metabolites at FDR<0.05. However, 251 DEGs by location, implicating immune response and oxidative phosphorylation pathways, were identified, while season of birth was associated with 2585 DEGs, over-represented in fibrosis signaling and metabolism pathways. Finally, transcription factor analysis identified 226 and 282 transcription factors associated with location and season, respectively, related to cell proliferation, differentiation, and the immune system. These alterations may have significant implications for fetal development and other pathologic processes, highlighting the importance of monitoring environmental exposures during pregnancy.

Fish predation affects invertebrate community structure of tropical temporary ponds, with downstream effects on phytoplankton that are obscured by pesticide pollution

Aquatic biota of tropical temporary ponds typically experience a wide range of stressors that can drive the structure and dynamics of natural communities. Particularly in regions with intense agricultural activity, aquatic biota may not only experience predation pressure but also stress from pesticides that inadvertently enter the ponds. We increasingly understand how these different sources of stress affect classic model taxa under controlled laboratory conditions, but how predators and pesticides may jointly affect pond invertebrate communities is still unclear, particularly for tropical systems. Here, we conducted an outdoor mesocosm experiment to study how fish predation combined with exposure to an environmentally relevant concentration of the commonly used insecticide cypermethrin (0.8 ng/L) affects the structure of invertebrate communities, and its potential effects on leaf litter decomposition and invertebrate grazing efficiency as measures of ecosystem functioning. A total of seven invertebrate taxa were recorded in the mesocosm communities. Fish predation effectively lowered the number of invertebrate taxa, with fish mesocosms being dominated by high densities of rotifers, associated with lower phytoplankton levels, but only when communities were not simultaneously exposed to cypermethrin. In contrast, cypermethrin exposure did not affect invertebrate community structure, and neither fish predation nor cypermethrin exposure affected our measures of ecosystem functioning. These findings suggest that predation by killifish can strongly affect invertebrate community structure of tropical temporary ponds, and that downstream effects on phytoplankton biomass can be mediated by exposure to cypermethrin. More broadly, we contend that a deeper understanding of (tropical) temporary pond ecology is necessary to effectively manage these increasingly polluted systems.

Co-exposure to polystyrene microplastics and cypermethrin enhanced the effects on hepatic phospholipid metabolism and gut microbes in adult zebrafish

Microplastics (MPs) can absorb environmental pollutants from the aquatic environment to cause mixed toxicity, which has received widespread attention. However, studies on the joint effects of MPs and insecticides are limited. As one of the most widely used pyrethroids, there was a large amount of residual cypermethrin (CYP) in water due to insufficient decomposition. Here, adult female zebrafish were exposed to MPs, CYP, and their mixtures for 21 days, respectively. After exposures, the MPs and CYP caused tissue damage to the liver. Hepatic triglyceride (TG) level increased significantly after MPs + CYP exposure, and the expression of genes about glycolipids metabolism was significantly altered. Furthermore, metabolome results suggested that MPs + CYP exposure resulted in increased content of some glycerophospholipid, affecting phospholipid metabolism-related pathways. In addition, through 16 s rDNA sequencing, it was found that MPs + CYP led to significant changes in the proportion of dominant phyla. Interestingly, Cetobacterium which increased in CYP and the co-exposure group was positively correlated with most lipid metabolites. Our results suggested that co-exposure to MPs and CYP enhanced the disturbances in hepatic phospholipid metabolism by affecting the gut microbial composition, while these changes were not observed in separate treatment groups. These results emphasized the importance of studying the joint toxicity of MPs and insecticides.

Cypermethrin: An Emerging Pollutant and Its Adverse Effect on Fish Health and some Preventive Approach-A Review

Pesticides are substance that are used to manage pests, such as aquatic weeds, plant diseases and insects. It has been shown that these substances are highly hazardous to fish as well as other organisms that are part of the food chain. The presence of cypermethrin in food and groundwater has raised environmental concerns, there is a need to develop economical, rapid, and reliable techniques that can be used for field applications Many studies have shown that Cypermethrin (CYP) can cause toxic effect in various animals including fishes. But the molecular mechanism behind the toxicity mediated Cypermethrin (CYP) at genome levels and proteome levels is still need to be studied. However, there is a gap in emerging and undeveloped nations to begin to use these methods and several other recently developed approaches to inhibit the negative consequences and enhance health which may be profitable. The toxicological information currently available might be used to gain a clear understanding of the possibilities of these synthetic pyrethroid insecticides causing various health hazards to environmental and provides insight for future research evaluating the toxic effects of pyrethroid insecticides. This present review article is concerned with the toxicological effects of pesticides and a brief overview of sources, classification of pesticides with an emphasis on the effects of Cypermethrin (CYP) on fish as well mode of toxicity and the mechanism of action (CYP) and toxicity signs in several fish species have been illustrated. The primary controls and appropriate preventive measures that must be adopted are also discussed.

Ligand-based designing of DPP-4 inhibitors via hybridization; synthesis, docking, and biological evaluation of pyridazine-acetohydrazides

A series of novel pyridazine-acetohydrazide hybrids were designed, synthesized, and evaluated for their in vitro and in vivo antihyperglycemic activity. In this context, pyridazine-acetohydrazides (6a-6p) were synthesized by coupling substituted aldehyde with 2-(5-cyano-6-oxo-3,4-diphenylpyridazine-1-6H-yl) acetohydrazide, which was prepared via the reaction of pyridazine ester with hydrazine hydrate. The molecular docking study was carried out to examine the binding affinities and interaction of designed compounds against the DPP-4 enzyme. Compounds 6e, 6f, 6l, and 6n exhibited interaction with active residue. In silico ADMET properties, and toxicity studies corroborated that compounds were found to have good bioavailability and less toxic. The synthesized compounds were further estimated for in vitro DPP-4 activity. Compounds 6e and 6l were found as the most effective DPP-4 inhibitor in this series with IC50 values (6.48, 8.22 nM) when compared with sitagliptin (13.02 nM). According to the toxicity assay compound, 6l showed very less toxicity at a higher concentration so further selected for the in vivo antihyperglycemic activity.

Endocrine disruptive toxicity of cypermethrin in Labeo catla: Involvement of genes and proteins related to the HPG axis

Cypermethrin (CYP) is a synthetic pyrethroid abundantly used in agriculture and aquaculture. It is an established potent endocrine disruptor to fish, yet the molecular mechanism behind its reproductive toxicity remains unclear. In this study, fish Labeo catla (Catla) was exposed to environmentally relevant concentration of CYP (0.7 μg/L) and 0.14 μg/L for 30 days. The changes in circulating sex steroids, genes, and hormones linked to the hypothalamic-pituitary-gonadal (HPG) axis, stress response and associated histological alterations were studied. Significant decline (P < 0.05) in serum 17 beta (β) estradiol (E2), 11 ketotestosterone (11-KT), and brain (FSH and GnRH) were observed in 0.7 μg/L dose of CYP. These effects may be due to the down-regulated expression of the upstream genes of the HPG axis i.e. Kiss 1 and Kiss 2, which further downregulates the expression of the GnRH gene. The decreased level of E2 and 11-KT also affects the vitellogenin (Vtg) gene expression, reducing the production of Vtg, a crucial protein for ovarian development. Principal component analysis (PCA) revealed the relationship between CYP and the biosynthesis of sex steroids. The toxic effect of CYP was also visible in antioxidant enzyme assay and related histological alterations. Overall, the study elucidated that long-term exposure to CYP, even at an environmentally relevant dose, may affect reproductive potential and fish recruitment. The study provides important insights into molecular mechanisms underlying CYP-induced endocrine disruption in fish, and it also raises questions about CYP's potential toxicity at environmentally relevant concentration in terms of understanding ecological risk.

Molecular and phenotypic effects of early exposure to an environmentally relevant pesticide mixture in the Pacific oyster, Crassostrea gigas

Early life stages are crucial for organism development, especially for those displaying external fertilization, whose gametes and early stages face environmental stressors such as xenobiotics. The pacific oyster, Crassostrea gigas, is considered a model species in ecotoxicology because of its ecological characteristics (benthic, sessile, filter feeding). So far studies have investigated the impact of xenobiotics at embryotoxic, genotoxic and physiological endpoints, sometimes at the multigenerational scale, highlighting the role of epigenetic mechanisms in transmitting alterations induced by exposure to single xenobiotics. However, to date, little is known about the impact of environmentally-mimicking contaminants cocktails. Thus, we examined the impact of an early exposure to environmentally relevant mixture on the Pacific oyster life history. We studied transcriptomic, epigenetic and physiological alterations induced in oysters exposed to 18 pesticides and metals at environmental concentration (nominal sum concentration: 2.85 μg.L-1, measured sum concentration: 3.74 ± 0.013 μg.L-1) during embryo-larval stage (0-48 h post fertilization, hpf). No significant differences in embryo-larval abnormalities at 24 hpf were observed during larval and spat rearing; the swimming behaviour of exposed individuals was disturbed, while they were longer and heavier at specific time points, and exhibited a lower epinephrine-induced metamorphosis rate as well as a higher survival rate in the field. In addition, RNA-seq analyses of gastrula embryos revealed the differential expression of development-related genes (e.g. Hox orthologues and cell cycle regulators) between control and exposed oysters. Whole-genome DNA methylation analyses demonstrated a significant modification of DNA methylation in exposed larvae marked by a demethylation trend. Those findings suggest that early exposure to an environmentally relevant pesticide mixture induces multi-scale latent effects possibly affecting life history traits in the Pacific oyster.

Bio-efficacy of aluminum phosphide and cypermethrin against some physiological and biochemical aspects of Chrysomya megacephala maggots

Carrion flies play a significant role in forensic entomotoxicology, where they are employed as alternative samples when traditional samples are unavailable. In situations of poisoned death, these toxins disrupt insect development and affect forensic entomology analyses. So, forensic entomotoxicologists must be aware of this impact. The present study aimed to determine the effects of aluminum phosphide (AlP) and cypermethrin (CP) on the biochemical parameters and antioxidant enzymes of the third instar of Chrysomya megacephala maggots. C. megacephala was reared on normal and poisoned rabbit carcasses with aluminum phosphide and cypermethrin. The third larval instar of C. megacephala was studied using by spectrophotometer for detection of total protein, (TP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), total antioxidant capacity (TAC), superoxide dismutase (SOD), glutathione s-transferase (GST), catalase (CAT) and malondialdehyde (MDA). The results indicated to significantly decrease of TP, TAC, SOD, GST and CAT and increase of AST, ALT and MDA in the maggots reared on the poisoned carcasses with AlP or CP compared with control group. In conclusion, the tested insecticides brought about a decrease antioxidant enzyme activity and increase of MDA could be involved in free radicals in C. megacephala larvae leading to oxidative stress by these insecticidal components.

Lead modification via computational studies: Synthesis of pyrazole-containing β-amino carbonyls for the treatment of type 2 diabetes

This article describes studies on the design, synthesis, and biological evaluation of pyrazole-containing β-amino carbonyl compounds (5a-5q) as DPP-4 inhibitors and anti-diabetic agents. In contrast, mannich reactions went smoothly with bismuth nitrate (Bi (NO₃ )₃ ) catalyst in the presence of ethanol and produced pyrazole-containing β-amino carbonyl compounds in good yield. Molecular docking studies of designed derivatives with DPP-4 enzyme (PDB: 2OLE), compounds 5d, 5h, 5j, and 5k showed excellent interaction. 3D QSAR and pharmacophoric model studies were also carried out. ADMET parameters, pharmacokinetic properties, and in vivo toxicity studies further confirmed that all the designed compounds were found to have good bioavailability and were less toxic. Further, these compounds were evaluated as enzyme-based in vitro DPP-4 inhibitory activity, and 5d, 5h, 5i, 5j, and 5k exhibited IC₅₀ toward DPP-4 enzyme of 10.52, 10.41, 5.55, 4.16, and 7.5 nM, respectively. The most potent compound, 5j, was further selected for in vivo anti-diabetic activity using an STZ-induced diabetic mice model, and 5j showed a significant diabetic control effect.

In silico and in vivo assessment of developmental toxicity, oxidative stress response & Na+/K+-ATPase activity in zebrafish embryos exposed to cypermethrin

Cypermethrin (CYP), a synthetic type II pyrethroid pesticide, is extensively used to control pests in industrial, domestic, and agricultural environments. However, its indiscriminate use leads to a potential threat to aquatic organisms. Although several reports focussed on developmental toxicity effects, a concise study combining cardiotoxicity along with Na⁺/K⁺-ATPase activity and molecular docking of developmental proteins with CYP was lacking. This present study was designed to address this gap to comprehend the impact of CYP exposure (0, 25, 100 and 200 µg/L) on embryonic zebrafish. As a result, CYP delayed the hatching rate, reduced heart rate, increased mortality rate and induced numerous morphological abnormalities. Subsequently, CYP induced oxidative stress in treated zebrafish embryos with the concomitant increase in antioxidant enzymes (SOD and CAT) and malondialdehyde production. In addition, an alteration in AChE, NO content and Na⁺/K⁺-ATPase activity was observed, suggesting a disruption in cardiac development and ion regulation. Furthermore, AO staining showed notable apoptotic cells which are supported by alteration in apoptosis-related gene expressions. Moreover, to explore the putative targets of CYP, computational docking with developmental proteins (WNT3A, WNT8A, GATA-4, Nkx 2-5 and ZHE1) showed strong interactions and binding. Taken together, our findings provide a better understanding of assessing the ecotoxicological risk information and the mode of action underlying the development of teleost fishes following CYP exposure. Meanwhile, the pioneering nature of this study is to emphasize the future use of Na⁺/K⁺-ATPase activity as a potential toxicity biomarker and in silico molecular docking studies to complement developmental toxicity findings.

Enantioselectivity in the toxicological effects of chiral pesticides: A review

As a special category of pesticides, chiral pesticides have increased the difficulty in investigating pesticide toxicity. Based on their usage, chiral pesticides can be divided into insecticides, herbicides, and fungicides. Over the past decades, great efforts have been made on elucidating their toxicological effects. However, no literature has reviewed the enantioselective toxicity of chiral pesticides since 2014. In recent years, more chiral pesticides have been registered for application. As such, huge research progresses have been achieved in enantioselective toxicity of chiral pesticides. Generally, more researches have remedied the knowledge gap in toxicological effects of old and new chiral pesticides. And the toxicological endpoints being evaluated have become more specific rather than centering on basic toxicity and target organisms. Besides, the underlying mechanisms accounting for the enantioselectivity in toxicological effects of chiral pesticides have been discussed as well. All in all, this review provides the critical knowledge for risk assessments, and help to drive the green-technology of single- or enriched-enantiomer pesticides and formulation of relevant laws and regulations.

DNA repair genes play a variety of roles in the development of fish embryos

Embryogenesis is one of the most important life stages because it determines an organism's healthy growth. However, embryos of externally fertilizing species, such as most fish, are directly exposed to the environment during development and may be threatened by DNA damaging factors (pollutants, UV, reactive oxygen species). To counteract the negative effects of DNA fragmentation, fish embryos evolved complex damage response pathways. DNA repair pathways have been extensively studied in some fish species, such as zebrafish (Danio rerio). Our literature review, on the other hand, revealed a paucity of knowledge about DNA damage response and repair in non-model aquaculture fish species. Further, several pieces of evidence underlie the additional role of DNA repair genes and proteins in organogenesis, spatiotemporal localization in different tissue, and its indispensability for normal embryo development. In this review, we will summarize features of different DNA repair pathways in course of fish embryo development. We describe how the expression of DNA repair genes and proteins is regulated during development, their organogenetic roles, and how the expression of DNA repair genes changes in response to genotoxic stress. This will aid in addressing the link between genotoxic stress and embryo phenotype. Furthermore, available data indicate that embryos can repair damaged DNA, but the effects of early-life stress may manifest later in life as behavioral changes, neoplasia, or neurodegeneration. Overall, we conclude that more research on DNA repair in fish embryos is needed.

Environmental Impact of Pharmaceutical Pollutants: Synergistic Toxicity of Ivermectin and Cypermethrin

Veterinary antiparasitic pharmaceuticals as well as pesticides have been detected in surface waters, and they may cause several toxic effects in this environmental compartment. In the present study, we evaluated the toxicity after exposure of different concentration of ivermectin (IVM; 50, 100, and 200 μg L⁻¹) and cypermethrin (CYP; 5, 10, and 25 μg L⁻¹) and the combination of these two compounds at non-toxic concentration (IVM 100 + CYP 5 μg L⁻¹) in zebrafish embryos. Combination of IVM at 100 μg L⁻¹ with CYP at 5 μg L⁻¹ exposure induced hatching delay and malformations at 96 hpf in zebrafish larvae as well as significant induction of cell death in zebrafish larvae. At the same time, the two single concentrations of IVM and CYP did not show a toxic effect on zebrafish development. In conclusion, our study suggests that IVM and CYP show a synergistic effect at common, ineffective concentrations, promoting malformation and cell death in fish development.

circRNA-based biomarker candidates for acute cypermethrin and chlorpyrifos toxication in the brain of Zebrafish (Danio rerio)

Circular RNAs (circRNAs) are a new class of non-endogenous coding RNA and an area with a lot of research interest and activity. Cypermethrin and chlorpyrifos have been shown to cause serious toxicological damage in the brain of fish and other non-target organisms. However, circRNAs associated with acute brain toxicity caused by cypermethrin and chlorpyrifos have not been studied yet. In this study, circRNAs were identified and characterized using RNA-seq in Zebrafish brains exposed to acute cypermethrin and chlorpyrifos toxicity. A total of 10,375 circRNAs were detected. It was determined that 6 circRNAs were up-regulated, 10 circRNAs were down-regulated in CYP brain samples compared to controls. In addition, it was found that 57 circRNAs are up-regulated and 3 circRNAs down-regulated in CPF brain samples compared to controls. Moreover, 62 circRNAs were down-regulated in the CYP samples, when CYP and CPF samples were compared. However, up-regulated circRNA could not be detected. It was revealed that the detected circRNAs specifically regulated the MAPK signaling pathway, endocytosis mechanism, apoptosis, and p53 signaling pathway. This study, which was conducted for the first time in terms of the subject of the study, could bring a different perspective, especially to pesticide toxicity studies.

Pesticide sensitivity of Nothobranchius neumanni, a temporary pond predator with a non-generic life-history

Pesticides are crucial to improve agricultural productivity, but often adversely affect surrounding aquatic systems and their fauna. To determine the environmental risk of pesticides, routine ecotoxicological tests are performed on several organisms, including standard fish models. However, these typically do not include fish species from variable habitats and with non-generic life-histories. In particular, inhabitants from temporary ponds such as annual killifish are conventionally understood to be resilient to natural stressors which could translate to higher pesticide resistance or, alternatively, trade-off with their resistance to pesticides and render them more sensitive than classic fish models. Using standard exposure tests, we assessed short-term toxicity effects of two commonly used pesticides, Roundup and cypermethrin, on the annual killifish Nothobranchius neumanni, and compared its sensitivity with that of classic fish models. For Roundup, we found a 72 h-LC₅₀ of 1.79 ± 0.11 mg/L, which is lower than the values reported for zebrafish, medaka, fathead minnow and rainbow trout, suggesting that N. neumanni is more sensitive to the compound. The opposite was true for cypermethrin, with a 72 h-LC₅₀ of 0.27 ± 0.03 mg/L. However, these LC₅₀-values do not deviate strongly from those reported for other fish species, supporting earlier findings in the congeneric N. furzeri that the sensitivity of annual killifish to pollutants is similar to that of classic fish models despite their assumed robustness to environmental stress.

GR15 peptide of S-adenosylmethionine synthase (SAMe) from Arthrospira platensis demonstrated antioxidant mechanism against H2O2 induced oxidative stress in in-vitro MDCK cells and in-vivo zebrafish larvae model

GR15 is a short molecule or peptide composed of aliphatic amino acids and possesses to have antioxidant properties. The GR15, ¹GGGAFSGKDPTKVDR¹⁵ was identified from the protein S-adenosylmethionine synthase (SAMe) expressed during the sulfur departed state of Arthrospira platensis (spirulina or cyanobacteria). The in-silico assessment and the structural features of GR15 showed its antioxidant potency. Real-time PCR analysis found the up-regulation of ApSAMe expression on day 15 against oxidative stress due to 10 mM H₂O₂ treatment in A. platensis (Ap). The antioxidant activity of GR15 was accessed by the cell-free antioxidant assays such as ABTS, SARS, HRAS and NO; the results showed dose-dependent antioxidant activity. The toxicity assay was performed in both in vitro and in vivo models, in which peptide does not exhibit any toxicity in MDCK cell and zebrafish embryos. The intercellular ROS reduction potential of GR15 peptide was also investigated in both in vitro and in vivo models including LDH assay, antioxidant enzymes (SOD and CAT), and fluorescent staining assay (DCFDA, Hochest and Acridine orange sting) was performed; the results showed that the GR15 peptide was effectively reduced the ROS level. Further, RT-PCR demonstrated that GR15 enhanced the antioxidant property and also up-regulated the antioxidant gene, thus reduced the ROS level in both in vitro and in vivo models. Based on the results obtained from this study, we propose that GR15 has the potential antioxidant ability; hence further research can be directed towards the therapeutic product or drug development against disease caused by oxidative stress.

Nuciferine Attenuates Doxorubicin-Induced Cardiotoxicity: An In Vitro and In Vivo Study

Chemotherapeutic drugs are a known factor that impairs the system of life due to their severe side effects. A more worrying fact is that the patients administered with doxorubicin fall under the risk of cardiotoxicity. The evolution of exploring plant-derived compounds is a possible way to combat health issues in therapeutic applications. Hence, this study focuses on the protective effect of plant-based compound nuciferine (NFN) against doxorubicin-induced cardiotoxicity in both in vitro and in vivo models. In this investigation, nuciferine significantly reduces DOX-mediated cardiotoxicity by mitigating reactive oxygen species, thereby preventing DNA fragmentation, regulating apoptosis genes and reducing the caspase 3/7 levels in vitro. Besides, nuciferine has shown significant protection against DOX-induced cardiac impairment and the upregulation of cardiogenic markers in vivo. The DOX-induced oxidative stress can be mitigated via enhancing the endogenous antioxidants, thereby controlling ROS-mediated apoptosis. In virtue of these potential features, nuciferine can be a budding candidate to address therapeutic needs.

Oxidative stress induced antioxidant and neurotoxicity demonstrated in vivo zebrafish embryo or larval model and their normalization due to morin showing therapeutic implications

AIMS

The study examined that morin as possible antioxidant and neuroprotective due to oxidative stress (H₂O₂) in zebrafish larval model.

MATERIALS AND METHODS

Zebrafish larvae were induced with oxidative stress using H₂O₂ at 1 mM; their behavioural changes were assessed through partition preference and horizontal compartment test. The head section without eyes and yolk sac of zebrafish larvae were employed for enzyme assays such as SOD, CAT, Thiobarbituric acid reactive substances assay, reduced glutathione, glutathione peroxidase activity, glutathione S transferase, Acetylcholinesterase activity and nitrate levels. Also, intracellular ROS and apoptosis in larval head was detected by DCFDA and acridine orange staining followed by gene expression studies.

KEY FINDINGS

Morin exposure was not harmful to the larvae at concentration between 20 and 60 μM, but it caused non-lethal deformity between 80 and 100 μM. In the partition test, zebrafish embryos treated with H₂O₂ showed cognitive impairment, whereas the morin-treated groups showed an improved behavioural activity. The study also found that restoring antioxidant enzymes and reduced lipid peroxidation which had a neuroprotective impact. Inhibition of NO overproduction and increased AChE activity were also shown to reduce the neuronal damage. Apoptosis and intracellular ROS levels were reduced in larvae when it was co-incubated with morin. Morin treatment up regulated the antioxidant enzymes against oxidative stress.

SIGNIFICANCE

Morin provides protection against H₂O₂ induced oxidative stress through a cellular antioxidant defence mechanism by up-regulating gene expression, thus increasing the antioxidant activity at cellular or organismal stage.

Stereoisomeric selectivity in the endocrine-disrupting potential of cypermethrin using in vitro, in vivo, and in silico assays

Despite the ubiquity of cypermethrin (CYP) stereoisomers in environment biota, the stereoisomeric selectivity of endocrine-disrupting potency of α-CYP, β-CYP, and θ-CYP has not been well studied. In this study, dual-luciferase reporter gene assays were adopted to analyze their potential endocrine-disrupting effects via four receptors (ERα, GRα, MR and RXR). The results showed that α-CYP was antagonistic to ERα, GRα, and MR with RIC₂₀ of 9.1 × 10^-7, 7.6 × 10^-7, and 1.0 × 10^-6 M, respectively. β-CYP exhibited only ERα-mediated agonistic activity with a REC₂₀ of 2.1 × 10^-6 M. None of the CYP stereoisomers interacted with RXR. Molecular docking indicated that α-CYP had the strongest binding capacity to GRα among the compounds. The expression levels of steroid hormone-related genes in human adrenocortical carcinoma (H295R) cells displayed that all three compounds inhibited the transcription of 3-βHSD, indicating the block of turning cholesterol into different hormones. Both α-CYP and β-CYP upregulated genes encoding estrogen- and aldosterone-forming enzymes including 17-βHSD, CYP19, STAR, and CYP11B2. Mortality and malformation toxicity assays in zebrafish embryos revealed that the order of toxicity was α-CYP > β-CYP > θ-CYP. Our results indicated that α-CYP may pose the strongest endocrine-disrupting effects. The data provided here will be helpful to systematically understand stereoisomeric selectivity in the endocrine-disrupting effects of cypermethrin.

An Overview on the Potential Hazards of Pyrethroid Insecticides in Fish, with Special Emphasis on Cypermethrin Toxicity

Simple Summary

Pyrethroid insecticides are extensively used in controlling agricultural insects and treatment of ectoparasitic infestation in farm animals. However, the unhygienic disposable and seepage of pyrethroids from the agricultural runoff will lead to contamination of the aquatic ecosystems, which will, in turn, induce harmful toxic effects in the exposed living aquatic organisms, including fish. Cypermethrin (CYP) is a commonly and widely used type II pyrethroid insecticide with known dangerous toxic effects on the exposed organisms. Serious hazardous effects of these toxicants have been reported in several fish species leading to high mortalities and economic losses of the exposed fish.

Abstract

Pesticides are chemicals used to control pests, such as aquatic weeds, insects, aquatic snails, and plant diseases. They are extensively used in forestry, agriculture, veterinary practices, and of great public health importance. Pesticides can be categorized according to their use into three major types (namely insecticides, herbicides, and fungicides). Water contamination by pesticides is known to induce harmful impacts on the production, reproduction, and survivability of living aquatic organisms, such as algae, aquatic plants, and fish (shellfish and finfish species). The literature and information present in this review article facilitate evaluating the toxic effects from exposure to various fish species to different concentrations of pesticides. Moreover, a brief overview of sources, classification, mechanisms of action, and toxicity signs of pyrethroid insecticides in several fish species will be illustrated with special emphasis on Cypermethrin toxicity.

Recent Advances on Detection of Insecticides Using Optical Sensors

Insecticides are enormously important to industry requirements and market demands in agriculture. Despite their usefulness, these insecticides can pose a dangerous risk to the safety of food, environment and all living things through various mechanisms of action. Concern about the environmental impact of repeated use of insecticides has prompted many researchers to develop rapid, economical, uncomplicated and user-friendly analytical method for the detection of insecticides. In this regards, optical sensors are considered as favorable methods for insecticides analysis because of their special features including rapid detection time, low cost, easy to use and high selectivity and sensitivity. In this review, current progresses of incorporation between recognition elements and optical sensors for insecticide detection are discussed and evaluated well, by categorizing it based on insecticide chemical classes, including the range of detection and limit of detection. Additionally, this review aims to provide powerful insights to researchers for the future development of optical sensors in the detection of insecticides.

Efficacy of Different Decontamination Processes in Mitigation of Pesticide Residues from Chili Crop

ABSTRACT

This study was conducted to evaluate the efficacy of seven decontamination processes in reducing the pesticide mixture load of six insecticides (quinalphos, profenophos, ethion, lambda-cyhalothrin, imidacloprid, and acetamiprid) from chili (Capsicum annuum L.). In the control treatment, the pesticide residues were extracted without following any decontamination procedure. The extraction of the insecticides from chili was initiated after 48 h of pesticide mixture spray and was done using the QuEChERS (quick, easy, cheap, effective, rugged, and safe) method. The quantitative analysis of four insecticides, namely quinalphos, profenophos, ethion, and lambda-cyhalothrin, was done by coupled gas chromatography-electron capture detection and that of imidacloprid and acetamiprid by high-performance liquid chromatography-UV detection. The results depicted reduction of pesticide residues in all the decontamination treatments compared with the control, although it varied for different insecticides. Solutions of 1 and 5% NaCl and 5% CH3COOH served as efficient decontaminants in removal of quinalphos, profenophos, ethion, and lambda-cyhalothrin residues from chili to ca. 90%, whereas for imidacloprid and acetamiprid there was a mild decontamination only (33.33 to 52.44%). The solutions of 5% NaHCO3 and 0.01% KMnO4 were effective only in removing lambda-cyhalothrin residues from the chili crop, but for all other pesticides the decontamination was not much pronounced.

HIGHLIGHTS

Tryptophan-tagged peptide from serine threonine-protein kinase of Channa striatus improves antioxidant defence in L6 myotubes and attenuates caspase 3-dependent apoptotic response in zebrafish larvae

This study reports the antioxidant property and molecular mechanism of a tryptophan-tagged peptide derived from a teleost fish Channa striatus of serine threonine-protein kinase (STPK). The peptide was tagged with tryptophan to enhance the antioxidant property of STPK and named as IW13. The antioxidant activity of IW13 peptide was investigated using in vitro methods such as DPPH, ABTS, superoxide anion radical scavenging and hydrogen peroxide scavenging assay. Furthermore, to investigate the toxicity and dose response of IW13 peptide on antioxidant defence in vitro, L6 myotubes were induced with generic oxidative stress due to exposure of hydrogen peroxide (H₂O₂). IW13 peptide exposure was found to be non-cytotoxic to L6 cells in the tested concentration (10, 20, 30, 40 and 50 μM). Also, the pre-treatment of IW13 peptide decreased the lipid peroxidation level and increased glutathione enzyme activity. IW13 peptide treatment upregulated the antioxidant enzyme genes: GPx (glutathione peroxidase), GST (glutathione S transferase) and GCS (glutamine cysteine synthase), in vitro in L6 myotubes and in vivo in zebrafish larvae against the H₂O₂-induced oxidative stress. The results demonstrated that IW13 renders protection against the H₂O₂-induced oxidative stress through a cellular antioxidant defence mechanism by upregulating the gene expression, thus enhancing the antioxidant activity in the cellular or organismal level. The findings exhibited that the tryptophan-tagged IW13 peptide from STPK of C. striatus could be a promising candidate for the treatment of oxidative stress-associated diseases.

Combined endocrine disruptive toxicity of malathion and cypermethrin to gene transcription and hormones of the HPG axis of male zebrafish (Danio rerio)

Cypermethrin (CYP) and malathion (MAT) have been widely used and are frequently detected in surface waters. The purpose of the present study was to investigate the endocrine disrupting toxicity of CYP, MAT, and CYP + MAT to 5-month-old male zebrafish (Danio rerio). After exposure, the hepatosomatic index (HSI) and gonadosomatic index (GSI) did not change significantly. Following exposure to the combination of 0.1 μg/L CYP +25 μg/L MAT, the E2 and VTG levels of male zebrafish were significantly increased compared to those after individual pesticide treatments. The molecular level of the hypothalamic-pituitary-gonadal (HPG) axis in zebrafish was studied; it was found that the expression of the estrogen-related genes, especially the vtg1 gene, was significantly altered in 0.1 μg/L CYP + 25 μg/L MAT. Overall, our observation indicated that CYP or MAT could disturb the hormonal balance, and their combination of 0.1 μg/L CYP +25 μg/L MAT could significantly enhance the estrogenic effect.

Benfuresate induces developmental toxicity in zebrafish larvae by generating apoptosis and pathological modifications

Benfuresate (2,3-dihydro-3,3-dimethylbenzofuran-5-yl ethanesulphonate) is a widely used pre-emergence herbicide of the benzofurane group, which works through the inhibition of lipid synthesis. During embryonic development of zebrafish, benfuresate retards growth while causing internal changes in the body, including alteration of the expression of cell cycle regulators, induction of apoptosis, and suppression of the circulatory system. Acute toxicity towards benfuresate is seen across the range of 5-15 μM in a dose-dependent manner and contributes to pathological conditions and subsequent morphological changes. For embryos 120 h post fertilization (hpf), benfuresate exposure results in an array of malformations involving eye or otolith development, pericardial edema, yolk sac edema, and abnormal curvature of the spine. Mechanistically, benfuresate exposure altered the transcription levels of the proliferative pathway genes ccnd1, ccne1, cdk2, and cdk6, all of which sensitize cells to apoptosis. Benfuresate exposure also affected vascular formation, including the formation of various vessels (DA, SIVs, CA, CV) whose functions in lymphatic-blood circulation were disrupted following decreased vegfaa, vegfc, flt1, flt4, and kdrl expression. These findings provide evidence of embryo-larval toxicity due to benfuresate and highlight the perils of herbicide exposure for non-target organisms far removed from application sites, especially in aquatic environments.

Intracellular ROS scavenging and antioxidant regulation of WL15 from cysteine and glycine-rich protein 2 demonstrated in zebrafish in vivo model

Antioxidant peptides are naturally present in food, especially in fishes, and are considered to contain rich source of various bioactive compounds that are structurally heterogeneous. This study aims to identify and characterize the antioxidant property of the WL15 peptide, derived from Cysteine and glycine-rich protein 2 (CSRP2) identified from the transcriptome of a freshwater food fish, Channa striatus. C. striatus is already studied to contain high levels of amino acids and fatty acids, besides traditionally known for its pharmacological benefits in the Southeast Asian region. In our study, in vitro analysis of WL15 peptide exhibited strong free radical scavenging activity in 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), superoxide anion radical and hydrogen peroxide (H2O2) scavenging assay. Further, to evaluate the cytotoxicity and dose-response, the Human dermal fibroblast (HDF) cells were used. Results showed that the treatment of HDF cells with varying concentrations (10, 20, 30, 40 and 50 μM) of WL15 peptide was not cytotoxic. However, the treatment concentrations showed enhanced antioxidant properties by significantly inhibiting the levels of free radicals. For in vivo assessment, we have used zebrafish larvae for evaluating the developmental toxicity and for determining the antioxidant property of the WL15 peptide. Zebrafish embryos were treated with the WL15 peptide from 4 h of post-fertilization (hpf) to 96 hpf covering the embryo-larval developmental period. At the end of the exposure period, the larvae were exposed to H2O2 (1 mM) for inducing generic oxidative stress. The exposure of WL15 peptide during the embryo-larval period showed no developmental toxicity even in higher concentrations of the peptide. Besides, the WL15 peptide considerably decreased the intracellular reactive oxygen species (ROS) levels induced by H2O2 exposure. WL15 peptide also inhibited the H2O2-induced caspase 3-dependent apoptotic response in zebrafish larvae was observed using the whole-mount immunofluorescence staining. Overall results from our study showed that the pre-treatment of WL15 (50 μM) in the H2O2-exposed zebrafish larvae, attenuated the expression of activated caspase 3 expressions, reduced Malondialdehyde (MDA) levels, and enhanced antioxidant enzymes, including superoxide dismutase (SOD) and catalase (CAT). The gene expression of antioxidant enzymes such as glutathione S-transferase (GST), glutathione peroxide (GPx) and γ-glutamyl cysteine synthetase (GCS) was found to be upregulated. In conclusion, it can be conceived that pre-treatment with WL15 could mitigate H2O2-induced oxidative injury by elevating the activity and expression of antioxidant enzymes, thereby decreasing MDA levels and cellular apoptosis by enhancing the antioxidant response, demonstrated by the in vitro and in vivo experiments.

Effects of cypermethrin on the hepatic transcriptome and proteome of the red claw crayfish Cherax quadricarinatus

Cypermethrin (CYP) is a synthetic pyrethroid broadly used for pest control, however, it is extremely toxic to aquatic organisms. To assess the toxicity of CYP in red claw crayfish Cherax quadricarinatus, transcriptional and proteomic approaches combining two-dimensional polyacrylamide gel electrophoresis and tandem mass spectrometry were used to compare the hepatic expression profiles. A total of 41,349 unigenes and 8839 differentially expressed genes (DEGs) were obtained, which were enriched in the process. The category of 779 (0.625 ng L^-1 CYP vs Con), 1963 (1.25 vs Con), and 2066 (1.25 vs 0.625) DEGs were screened. All findings suggested that CYP can induce antioxidant and biotransformation modulation variations in C. quadricarinatus to resist immunotoxicity and oxidative damages. The category of 196 (0.625 ng L^-1 CYP vs Con) specific proteins were differentially expressed: 24 proteins were upregulated, and 20 proteins were downregulated relative to CYP. Protein identification indicated the KEGG pathways of the human immunodeficiency virus 1 infection, insulin signaling pathway, and influenza A enriched. From the differential expression of the selected nine proteins, the increased Loc113824800, Rps19, Atp2, Rps10, Hsp40, Brafldraft_124327, and the decreased Loc117331934, Loc113213835, and Loc106806551 revealed. While for the verification of the eight genes in transcriptome and the above nine genes in proteomic, specifically, gpx5, ggt, loc106458463, chelonianin decreased in the 0.625 ng L^-1 CYP group. The transcripts of loc113816050, akr1d1 and gst, chelonianin and loc108675455 decreased and increased in the 1.25 ng L^-1 CYP group, respectively. The present study reflects the overall change in cellular structure and metabolism related to the resistance of pyrethroid insecticides.

Severe damages caused by Malathion exposure in Colossoma macropomum

The increase in pesticide use in response to agricultural demands poses a risk to non-target organisms, including fish. Integrated analysis of biochemical, histopathological and genetic parameters in fish exposed to Malathion insecticide provide information on the toxicity mechanisms of this pesticide, which is classified as a probable carcinogen for humans. The present study assessed the biological responses of Colossoma macropomum after exposure to Malathion. We started determining the lethal concentration, which is the concentration capable of killing 50% of the subjects in an acute toxicity test (LC₅₀-96 h), which was 15.77 ± 3.30 mgL^-1. The fish were, then, exposed to Malathion during 96 h at a sublethal concentration, 7.30 mgL^-1. Overall, we observed an increased activity of biotransformation and antioxidant enzymes, which reduced production of mitochondrial reactive oxygen species after 96 h exposure, as well as kept constant the mitochondrial respiration, Acetylcholinesterase activity and DNA damage. However, fish exposed to insecticide presented severe gill histopathological damage and increased expression of proto-oncogene ras. Taken together, the results suggest that, after four days of exposure to the Malathion, C. macropomum efficiently activates its defense mechanisms, suggesting that the basal response mechanisms are responsive. On the other hand, histopathologic damages evidenced the adverse effects of Malathion on fish, since it promoted gill necrosis and increased the expression of ras oncogene that is directly related to tumorigenesis events.

Pyrethroid pesticide exposure during early pregnancy and birth outcomes in southwest China: a birth cohort study

Despite the developmental toxicity reported in animals, few epidemiologic studies have investigated the potential effects of prenatal exposure to pyrethroid pesticides (PYRs) on fetal growth. A birth cohort study was conducted to examine the association between prenatal exposure to PYRs and birth outcomes, and a nested case-control study was conducted in this cohort to evaluate the effects of PYR on congenital defects. The assessment of PYR exposure was based on self-reported household pesticide use and urinary PYR metabolite levels. We found that pregnant women in this region were ubiquitously exposed to low-level PYRs, although few reported household pesticide use. Women who often ate bananas or cantaloupes had a higher level of urinary 3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (DBCA), and the number of fruit types consumed by pregnant women was positively related to the concentrations of 3-phenoxybenzoic acid (3PBA) and total PYR metabolites (P < 0.05). Increased urinary 4-fluoro-3-phenoxybenzoic acid (4F3PBA), DBCA, and total PYR metabolites were associated with increased birth weight, length, and gestational age, and with decreased risk of small for gestational age (SGA) and/or premature birth. However, maternal household pesticides use was related to congenital anomalies. Thus, although prenatal exposure to low-dose PYRs promoted the fetal growth, the beneficial effects of fruit intake may outweigh the adverse effects of pesticide exposure. This study provided us an insight into the biological mechanisms for the effect of prenatal PYR exposure on fetal development, and suggested that further investigations in a larger study population with low-dose PYR exposure is needed.

Mediation of oxidative stress toxicity induced by pyrethroid pesticides in fish

Organophosphate and organochlorine pesticides are banned in most countries because they cause high toxicity and bioaccumulation in non-target organisms. Pyrethroid pesticides have been applied to agriculture and aquaculture since the 1970s to replace traditional pesticides. However, pyrethroids are approximately 1000 times more toxic to fish than to mammals and birds. Fish-specific organs such as the gills and their late metabolic action against this type of pesticide make fish highly susceptible to the toxicity of pyrethroid pesticides. Oxidative stress plays an important role in the neurological, reproductive, and developmental toxicity caused by pyrethroids. Deltamethrin, cypermethrin, and lambda-cyhalothrin are representative pyrethroid pesticides that induce oxidative stress in tissues such as the gills, liver, and muscles of fish and cause histopathological changes. Although they are observed in low concentrations in aquatic environments such as rivers, lakes, and surface water they induce DNA damage and apoptosis in fish. Pyrethroid pesticides cause ROS-mediated oxidative stress in fish species including carp, tilapia, and trout. They also cause lipid peroxidation and alter the state of DNA, proteins, and lipids in the cells of fish. Moreover, changes in antioxidant enzyme activity following pyrethroid pesticide exposure make fish more susceptible to oxidative stress caused by environmental pollutants. In this review, we examine the occurrence of pyrethroid pesticides in the aquatic environment and oxidative stress-induced toxicity in fish exposed to pyrethroids.

A Microfluidic Paper-Based Analytical Device for Type-II Pyrethroid Targets in an Environmental Water Sample

A detection method for type-II pyrethroids in an environmental water sample using a microfluidic paper-based analytical device (µPAD) is reported here. The detection approach is based on the formation of cyanide from the hydrolysis of type-II pyrethroids and the colorimetric detection of cyanide on a layer-based µPAD. Parafilm and inexpensive laminating pouches were used to create a hydrophobic barrier for the assay on the µPAD. This detection approach was selective to type-II pyrethroids in water for which an environmental water sample was tested. The calibration curves for cypermethrin, deltamethrin, cyhalothrin, and fenvalerate ranged from 2 to 40 µg/mL without sample preconcentration. The lower concentrations of type-II pyrethroids can be assessed by including a preconcentration step prior to the detection on a µPAD. This detection system provides an alternative platform for fast, semiquantitative testing for pesticide contamination in environmental surface water by allowing for portability, low reagent/sample consumption, and low-cost testing.

Four cypermethrin isomers induced stereoselective metabolism in H295R cells

Cypermethrin (CP) is widely used for controlling agricultural and indoor vermin. Previous studies have reported the stereoselective difference of CP in biological activities. However, little is known about their potential mechanisms between metabolic phenotypes and endocrine-disrupting effects. Herein, nuclear magnetic resonance (NMR)-based metabolomics combining metabolite identification and pathway analysis were applied to evaluate the stereoselective metabolic cdisorders induced by CP isomers in human adrenocortical carcinoma cells (H295R) culture medium. Then, gene expression levels related to disturbed metabolic pathways were assessed to verify according to metabolic phenotypes. Metabolomics profiles showed that [(S)-cyano(3-phenoxyphenyl)methyl](1R,3R)-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropane-1-carboxylate [(1R,3R,αS)-CP] induced the most significant changes in metabolic phenotypes than did the other stereoisomers. There are 10 differential metabolites (isoleucine, valine, leucine, ethanol, alanine, acetate, aspartate, arginine, lactate, and glucose) as well as two significantly disturbed pathways, including "pyruvate metabolism" and "alanine, aspartate, and glutamate metabolism," that were confirmed in H295R cells culture medium of (1R,3R,αS)-CP compared with other stereoisomers. Polymerase chain reaction (PCR) array also confirmed the results of metabolomics. Our results can help to understand the potential mechanisms between the isomer selectivity in metabolic phenotypes and endocrine-disrupting effects. Data provided here not only lend authenticity to the cautions issued by the scientists and researchers but also offer a solution for the balance between environment and political regulations.

Phenotypic and transcriptomic changes in zebrafish (Danio rerio) embryos/larvae following cypermethrin exposure

Cypermethrin is one of the widely used type-II pyrethroid and the indiscriminate use of this pesticide leads to life threatening effects and in particular showed developmental effects in sensitive populations such as children and pregnant woman. However, the molecular mechanisms underlying cypermethrin-induced development toxicity is not well defined. To address this gap, the present study was designed to investigate the phenotypic and transcriptomic (next generation RNA-Seq method) impact of cypermethrin in zebrafish embryos as a model system. Zebrafish embryos at two time points, 24 h postfertilization (hpf) and 48 hpf were exposed to cypermethrin at a concentration of 10 μg/L. Respective control groups were maintained. Cypermethrin induced both phenotypic and transcriptomic changes in zebrafish embryos at 48 hpf. The phenotypic anomalies such as delayed hatching rate, increased heartbeat rate and deformed axial spinal curvature in cypermethrin exposed zebrafish embryos at 48 hpf as compared to its respective controls. Transcriptomic analysis indicated that cypermethrin exposure altered genes associated with visual/eye development and gene functional profiling also revealed that cypermethrin stress over a period of 48 h disrupts phototransduction pathway in zebrafish embryos. Interestingly, cypermethrin exposure resulted in up regulation of only one gene, tnnt3b, fast muscle troponin isoform 3T in 24 hpf embryos as compared to its respective controls. The present model system, cypermethrin exposed zebrafish embryos elaborates the toxic consequences of cypermethrin exposure during developmental stages, especially in fishes. The present findings paves a way to understand the visual impairment in sensitive populations such as children exposed to cypermethrin during their embryonic period and further research is warranted.

The protective effect of Hibiscus sabdariffa calyxes extract against cypermethrin induced oxidative stress in mice

Cypermethrin (Cyp) is a kind of pyrethroids compound that is broadly used against different species of insects and pests. Cyp can also elicit a range of neurotoxic, immunotoxic, genotoxic and reproductive toxic effects on various experimental organisms. The aim of this study was to evaluate the protective effects of Hibiscus sabdariffa against the toxicity damage induced by Cyp exposure. The Hibiscus sabdariffa calyxes extract was given to mice (200-500 mg/kg bw). The mice, which were treated with Cyp and Hibiscus sabdariffa, were divided into six groups of six mice each. Groups I, IV and VI were used as control and groups II C_YP control (20 mg/kg body weight)., groups III and V were treated with Hibiscus sabdariffa extract (200 and 500 mg/kg body weight) plus (20 mg/kg body weight) for 21 days Furthermore, HPLC was used to identify the compound fraction. This result showed Cyp -induced biochemical changes in all organs of mice. Cyp caused decreased CAT activity, inhibition of AChE activity and increased the levels of H₂O₂ and MDA in brain, heart, liver and kidney. Hibiscus sabdariffa exhibited antioxidant effect and significantly attenuated the neurotoxicity of Cyp. Hibiscus sabdariffa exhibits neuroprotective effects and can be an effective and novel alternative approach to reduce the risk caused by pyrethroid compound.

Nodularin induced oxidative stress contributes to developmental toxicity in zebrafish embryos

Nodularin (NOD) is a kind of cyanobacterial toxins. It is of concern due to elicit severe genotoxicity in humans and animals. The comprehensive evaluation of NOD-induced adverse effects in living organisms is urgently needed. This study is aimed to report the developmental toxicity and molecular mechanism using zebrafish embryos exposed to NOD. The embryonic toxicity induced by NOD is demonstrated by inhibition of embryo hatching, increase in mortality rate, abnormal heart rate, embryonic malformation as well as defects in angiogenesis and common cardinal vein remodeling. NOD triggered a decreased rate of angiogenesis through inhibiting endothelial cells migration. NOD induced embryonic cell apoptosis and DNA damage, which can be alleviated by antioxidant N-acetyl-L-cysteine. NOD significantly caused oxidative damage as indicated by changes in reactive oxygen species, superoxide dismutase, catalase, glutathione and malondialdehyde. NOD also altered the expression of vascular development-genes (DLL4, CDH5, VEGFA, VEGFC) and apoptosis-related genes (BAX, BCL-2, P53, CASPASE 3). Taken together, NOD induced adverse effect on zebrafish embryos development, which may be associated with oxidative stress and apoptosis through the activation of P53-BAX/BCL-2-CASPASE 3-mediated pathway.

tert-Butyl-p-benzoquinone induces autophagy by inhibiting the Akt/mTOR signaling pathway in RAW 264.7 cells

tert-Butyl-p-benzoquinone (TBBQ), a metabolite of tert-butylhydroquinone from food, has cytotoxicity, the underlying mechanism of which is not clear. In this study, the viability of RAW 264.7 cells exposed to TBBQ at concentrations of 0.5-10 μg mL^-1 was assayed by MTT. Results suggest that TBBQ decreased the viability in a dose-dependent manner. Monodansylcadaverine (MDC) staining results indicate the occurrence of autophagy induced by TBBQ, which was manifested by activation of LC3-II concurrent with the increased levels of Beclin1 and reduced levels of p62. Elevated lipid peroxide and decreased SOD activity by TBBQ exposure suggest the overproduction of ROS, which may account for the increase in the genotoxic stress protein p53. Both upregulation of p53 and reduction of Akt levels inhibited mTOR, which activated autophagy. Addition of 3-MA counteracted the impact of TBBQ on ATG proteins and cell viability. All of these results suggest that TBBQ induces autophagy of RAW 264.7 cells principally by inhibition of the Akt/mTOR signaling pathway, and they implicate ROS in this regulation.

The pyrethroid esfenvalerate induces hypoactivity and decreases dopamine transporter expression in embryonic/larval zebrafish (Danio rerio)

Esfenvalerate is a pyrethroid insecticide used widely for agricultural and residential applications. This insecticide has been detected in aquatic environments at concentrations that can induce sub-lethal effects in organisms. In this study, zebrafish embryos were used to examine the effects of environmentally-relevant concentrations of esfenvalerate on development and behavior. It was hypothesized that esfenvalerate exposure would impair locomotion due to its effects on the central nervous system. We also measured mitochondrial bioenergetics and the expression of genes (dopamine system) as putative mechanisms of locomotor impairment. Concentrations of 0.02, 0.2 and 2 μg/L esfenvalerate did not induce significant mortality nor deformity in zebrafish, but there was an acceleration in hatching time for zebrafish exposed to 2 μg/L esfenvalerate. As an indicator of neurotoxicity, the Visual Motor Response (VMR) test was conducted with 5, 6, and 7 dpf zebrafish after continuous exposure, and higher concentrations were used (4 and 8 μg/L esfenvalerate) to better discern age-and dose dependent responses in behavior. Experiments revealed that, unlike the other stages, 6 dpf larvae showed evidence for hypo-activity with esfenvalerate, suggesting that different stages of larval development may show increased sensitivity to pyrethroid exposure. This may be related to age-dependent maturation of the central nervous system. We hypothesized that reduced larval activity may be associated with impaired production of ATP and the function of mitochondria at earlier life stages, however dramatic alterations in oxidative phosphorylation were not observed. Based on evidence that dopamine regulates behavior and studies showing that other pyrethroids affect dopamine system, we measured transcripts involved in dopaminergic signaling. We found that dopamine active transporter was down-regulated with 0.2 μg/L esfenvalerate. Lastly, we comprehensively summarize the current literature (>20 studies) regarding the toxicity of pyrethroids in zebrafish, which is a valuable resource to those studying these pesticides. This study demonstrates that esfenvalerate at environmentally-relevant levels induces hypoactivity that are dependent upon the age of the zebrafish, and these behavioral changes are hypothesized to be related to impaired dopamine signaling.

Toxicity of the organophosphate insecticide sumithion to embryo and larvae of zebrafish

•

The 24 h LC₅₀ value of sumithion for embryo was 0.235 mg L⁻¹.

•

Several malformations were observed in embryos exposed to different concentrations of sumithion.

•

The 24, 48 and 72 h LC₅₀ values of sumithion for larvae were 0.620, 0.475 and 0.341 mg L⁻¹, respectively.

•

Different deformities were evident in the sumithion exposed larvae.

Sumithion, a synthetic organophosphate, is widely used as an agricultural insecticide and for control of tiger bug (Cicindela spp.) in larval rearing for aquaculture. An experiment was conducted to examine the effects of sumithion on embryological and larval development of zebrafish Danio rerio. Fertilized egg (n = 100) and larvae (n = 100) were exposed to six concentrations of sumithion (0, 0.1, 0.2, 0.4, 0.8 and 1.6 mg L⁻¹) in three replicates. LC₅₀ values for embryos and larvae were calculated by probit analysis. The 24 h LC₅₀ value of sumithion for embryo was 0.235 (0.079-0.428) mgL⁻¹. Increasing sumithion concentrations decreased hatching success and increased embryonic mortality. In embryos, sumithion induced several malformations including immature yolk sac, dark yolk sac, yolk sac bud, broken eggshell and notochord, unhatched eggs. Larval LC₅₀ values at 24, 48 and 72 h of various doses of sumithion exposure were 0.620 (0.436-0.963), 0.475 (0.302-0.801) and 0.341 (0.177-0.617) mgL⁻¹, respectively. Various physical deformities, including edema, notochord deformity, yolk sac damage, body arcuation, lordosis and black pigmentation on the yolk sac were evident in response to different concentrations of sumithion. The results of the current study indicate that sumithion exerts developmental toxicity to zebrafish embryos and larvae. It is expected that current findings will increase sensitivity about the toxic effect of sumithion in early development, as well the possibility of similar actions induced by other insecticides and pesticides.

Acute embryonic exposure of zebrafish to permethrin induces behavioral changes related to anxiety and aggressiveness in adulthood

Permethrin (PM) is one of the most used synthetic pyrethroid worldwide. Exposure to this compound during pregnancy and early childhood has been indicated as a risk factor for neurodevelopmental disorders. We evaluated the long-term effects of embryonic PM exposure in different stages of zebrafish development. Briefly, embryos (3 hpf) were exposed to sub-lethal concentrations of PM (25 and 50 μg.L^-1) during 24 h and then behavioral parameters were evaluated during embryonic (28 hpf), eleutheroembryonic (3 dpf), larval (7 dpf), and adult stages (90 dpf). PM exposure decreased spontaneous movement at 28 hpf and decreased thigmotaxis in eleutheroembryos. The long-term effects of PM include changes in non-motor behaviors such as fear and anxiety in larva and adults. Adults embryonically exposed to PM also showed a significant increase in aggressiveness parameters. These results demonstrated that embryonic exposure to PM induces persistent neurotoxic effects in adulthood, which can impair the cognitive and behavioral fitness of non-target species contributing to a rise in neurodevelopmental disorders.

Effects of norfloxacin nicotinate on the early life stage of zebrafish (Danio rerio): Developmental toxicity, oxidative stress and immunotoxicity

Norfloxacin nicotinate (NOR-N), an adduct of norfloxacin (NOR) and nicotinic acid, has been widely used for replacing NOR in animal husbandry and fishery industry. Nowadays, increasing evidences showed that NOR could pose toxic effects on fish and other aquatic organisms, but as its adduct, whether NOR-N could cause adverse effects on aquatic organisms is still unclear. To evaluate the toxic effects of NOR-N on the early life stage of zebrafish, we determined the changes in embryonic development (hatching rate, body length, malformation rate and mortality), antioxidant enzyme (superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (Gpx)) activities, malondialdehyde (MDA) content and gene expression levels related to antioxidant enzymes (Cu/Zn-sod, Mn-sod, CAT and Gpx) and innate immune system (tumor necrosis factor α (TNFα), interferon (IFN), Interleukin-1 beta (IL-1β), IL-8, CXCL-clc, CC-chemokine, lysozyme (Lzy) and complement factors (C3)) after embryonic exposure to NOR-N till 96 hpf. The results showed that NOR-N exposure could decreased the hatching rate and body length, and increased abnormality and mortality as concentration-dependent during embryonic development process. NOR-N induced oxidative stress in zebrafish larvae through increasing the contents of MDA and the activities of SOD, CAT and Gpx, as well as the mRNA levels of genes related to these antioxidant enzymes. Moreover, the expression of TNFα, IFN, IL-1β, IL-8, CXCL-clc, CC-chemokine, Lzy and C3 genes were significantly up-regulated after exposure to high concentration (5 and/or 25 mg/L) of NOR-N till 96 hpf, indicating that the innate immune system in zebrafish larvae was disturbed by NOR-N. Overall, our results suggested that NOR-N caused development toxicity, oxidative stress and immunotoxicity on the early life stage of zebrafish. Thus, widespread application of NOR-N might pose potential ecotoxicological risk on aquatic ecosystems.

Differences in life stage sensitivity of the beetle Tenebrio molitor towards a pyrethroid insecticide explained by stage-specific variations in uptake, elimination and activity of detoxifying enzymes

It is widely accepted that sensitivity towards pesticides varies significantly between species. Much less is known about the potential differences in pesticide sensitivity and its biological mechanism throughout the lifecycle of a single species. In the present study we used three life-stages (larvae, pupae and adult) of the holometabolous insect Tenebrio molitor to investigate: i) Life-stage specific differences in sensitivity towards the pyrethroid insecticide α-cypermethrin after topical exposure, and ii) whether these differences can be explained by the degree of uptake and/or excretion. Finally, we investigated if an efficient excretion coincided with higher activities of the detoxifying enzymes cytochrome P450 (P450), esterases (EST) and glutathione-S-transferease (GST). We found that mobility of adults of T. molitor was more affected by α-cypermethrin treatment than larvae and pupae. Mortality was relatively low for all life stages and did not vary significantly with dose within the duration of the experiment, which indicated that death was (at least partly) due to starvation (indirect effect of paralysis) rather that direct effects of the insecticide. Insecticide treatment during the pupal stage further impaired normal development from pupa to adult. Toxicokinetic measurements showed that cuticle penetration of α-cypermethrin differed significantly between life-stages. Approximately 50% of the applied insecticide had penetrated the adult cuticle after 1 h, whereas a maximum of 30% and 16% had penetrated the waxier cuticle of larvae and pupae. Further, the pupal stage lacked the ability to excrete compounds, and hence internal insecticide concentrations in pupae increased or stagnated until emergence of the adult. Finally, quantification of detoxification enzymes showed a markedly higher activity of P450 in adults and larvae compared to pupae. These findings suggest that assessing toxicity and/or risk of pesticides collectively for a species may not be adequate without taking into account the potential sensitivity differences between life stages.

Developmental toxicity and angiogenic defects of etoxazole exposed zebrafish (Danio rerio) larvae

Etoxazole, a chitin synthesis inhibitor, is widely used to control insects and mites by causing developmental defects. Despite the many advantages of pesticides, the inhibitory effects of most pesticides including etoxazole are based on biochemical reaction and their widespread application is considered as a major risk to human health and the environment because of bioaccumulation and non-target toxic effects. Though used in agricultural area, the pesticide residues run off through rivers or ocean, where diverse aquatic organisms live. Since there are no studies evaluating the risks of etoxazole exposure in embryogenesis of aquatic organisms, we investigated the adverse effects of etoxazole on development and angiogenesis in zebrafish embryos, which are considered to be an effective model for detecting ecotoxicological effects of widely used compounds, especially affecting aquatic organisms. Etoxazole induced yolk sac and heart edema, as well as loss of viability, abnormal heart rate, and developmental deficiency. Through a mechanistic approach, we also showed that etoxazole caused reactive oxygen species accumulation, inhibited the expression of cell cycle activating genes, and induced apoptosis. In addition, we investigated effects of etoxazole on cardiovascular development by demonstrating the loss of vascular structure in response to etoxazole exposure in fli1:eGFP transgenic zebrafish model. Collectively, this first assessment demonstrating the effects of etoxazole on embryogenesis and cardiovascular development provides clear evidence for the toxicity of etoxazole and contributes important data towards formulating safety guidelines on the potential hazards of etoxazole for aquatic environment.

Enantioselectivity in endocrine disrupting effects of four cypermethrin enantiomers based on in vitro models

Cypermethrin (CP) is a kind of chiral pesticides that has been defined as endocrine disrupting chemical. The diversity in bioactivity, toxicity, metabolism, bioaccumulation, and degradation behaviors of CP enantiomers as well as the research deficiency had made the risk assessment of CP enantiomers very complicated. Herein, four CP enantiomers were separated as target chemicals to investigate their enantioselective endocrine disrupting effects. Firstly, dual-luciferase reporter gene assays were adopted to investigate their potential endocrine disrupting effects via various receptors. The expression levels of steroid hormones related genes and hormone secretion levels in H295R cell were measured to verify the results. Results from the reporter gene assay showed that 1R-cis-αS-CP (CP11) exhibited glucocorticoid receptor (GR), mineralocorticoid receptor (MR), and thyroid receptor (TR) antagonistic activity with the RIC₂₀ values of 9.22 × 10^-7, 3.33 × 10^-7, and 4.47 × 10^-7 M, respectively; 1R-trans-αS-CP (CP21) also showed androgen receptor (AR) agonist activity and estrogen receptor (ER) antagonistic activity with the REC₂₀ and RIC₂₀ values were 1.07 × 10^-4 M and 4.78 × 10^-6 M, respectively. Results of qRT-PCR and hormone measurement also showed that CP11 and CP21 could disturb the expression of steroid hormones related genes and hormone secretion accordingly. Results provided here can help to understand the enantioselective ecological and health risks of CP enantiomers comprehensively and provide constructive guidance for the safe use of chiral pesticides and the invention of green pesticides.

Environmental Mechanisms of Neurodevelopmental Toxicity

PURPOSE OF REVIEW

With the incidence of neurodevelopmental disorders on the rise, it is imperative to identify and understand the mechanisms by which environmental contaminants can impact the developing brain and heighten risk. Here, we report on recent findings regarding novel mechanisms of developmental neurotoxicity and highlight chemicals of concern, beyond traditionally defined neurotoxicants.

RECENT FINDINGS

The perinatal window represents a critical and extremely vulnerable period of time during which chemical insult can alter the morphological and functional trajectory of the developing brain. Numerous chemical classes have been associated with alterations in neurodevelopment including metals, solvents, pesticides, and, more recently, endocrine-disrupting compounds. Although mechanisms of neurotoxicity have traditionally been identified as pathways leading to neuronal cell death, neuropathology, or severe neural injury, recent research highlights alternative mechanisms that result in more subtle but consequential changes in the brain and behavior. These emerging areas of interest include neuroendocrine and immune disruption, as well as indirect toxicity via actions on other organs such as the gut and placenta. Understanding of the myriad ways in which the developing brain is vulnerable to chemical exposures has grown tremendously over the past decade. Further progress and implementation in risk assessment is critical to reducing risk of neurodevelopmental disorders.