Effects of Chlorpyrifos on Cholinesterase and Serine Lipase Activities and Lipid Metabolism in Brains of Rainbow Trout (Oncorhynchus mykiss)

Comprehensive multi-omics investigation of sub-chronic toxicity induced by Cadmium and Triazophos Co-exposure in hook snout carps (Opsariichthys bidens)

The coexistence of heavy metals and pesticides poses a critical challenge in agricultural ecosystems. Traditional toxicity assessments often focus only on the individual impacts of either pesticides or heavy metals. Here, the untargeted metabolomics and 16 S rRNA sequencing were used to assess the individual and combined effects of cadmium (Cd) and triazophos (TRI) on hook snout carps (Opsariichthys bidens). Cd caused much more serious impacts on hepatic metabolism and gut microbiota than those in TRI. Combined Cd and TRI exposure synergistically affected hepatic metabolism, causing mitochondrial dysfunction and even oxidative damage. Simultaneously, 16 S rRNA sequencing highlighted significant variations in the composition and abundance of gut microbiota. A noteworthy connection emerged between these distinct microbiota profiles and disruptions in energy metabolism, ultimately leading to disorders in metabolites. These findings enhanced the understanding of risks posed by heavy metals and pesticides, providing insights for better environmental risk assessments of aquatic organisms.

A comparative study on targeted gene expression in zebrafish and its gill cell line exposed to chlorpyrifos

Chlorpyrifos (CPF) is an organophosphorus-based insecticide, which is known to pose a serious risk to aquatic animals. However, the mechanisms of CPF toxicity in animals still remain unclear. The present investigation aimed to compare the potential effects of CPF in zebrafish (Danio rerio) and its gill cell line (DrG cells). Based on the in vivo study, the LC50 was calculated as 18.03 µg/L and the chronic toxic effect of CPF was studied by exposing the fish to 1/10th (1.8 µg/L) and 1/5th (3.6 µg/L) of the LC50 value. Morphological changes were observed in fish and DrG cells which were exposed to sublethal concentrations of CPF. The results of MTT and NR assays showed significant decline in the survival of cells exposed to CPF at 96 h. The production of reactive oxygen species in DrG cells and expression levels of antioxidant markers, inflammatory response genes (cox2a and cox2b), cyp1a, proapoptotic genes (bax), antiapoptotic gene (bcl2), apoptotic genes (cas3 and p53), and neuroprotective gene (ache) were determined in vivo using zebrafish and in vitro using DrG cells after exposure to CPF. Significant changes were found in the ROS production (DrG cells) and in the expression of inflammatory, proapoptotic, and apoptotic genes. This study showed that DrG cells are potential alternative tools to replace the use of whole fish for toxicological studies.

The Roles of Diet and Habitat Use in Pesticide Bioaccumulation by Juvenile Chinook Salmon: Insights from Stable Isotopes and Fatty Acid Biomarkers

Stable isotopes (SI) and fatty acid (FA) biomarkers can provide insights regarding trophic pathways and habitats associated with contaminant bioaccumulation. We assessed relationships between SI and FA biomarkers and published data on concentrations of two pesticides [dichlorodiphenyltrichloroethane and degradation products (DDX) and bifenthrin] in juvenile Chinook Salmon (Oncorhynchus tshawytscha) from the Sacramento River and Yolo Bypass floodplain in Northern California near Sacramento. We also conducted SI and FA analyses of zooplankton and macroinvertebrates to determine whether particular trophic pathways and habitats were associated with elevated pesticide concentrations in fish. Relationships between DDX and both sulfur (δ34S) and carbon (δ13C) SI ratios in salmon indicated that diet is a major exposure route for DDX, particularly for individuals with a benthic detrital energy base. Greater use of a benthic detrital energy base likely accounted for the higher frequency of salmon with DDX concentrations > 60 ng/g dw in the Yolo Bypass compared to the Sacramento River. Chironomid larvae and zooplankton were implicated as prey items likely responsible for trophic transfer of DDX to salmon. Sulfur SI ratios enabled identification of hatchery-origin fish that had likely spent insufficient time in the wild to substantially bioaccumulate DDX. Bifenthrin concentration was unrelated to SI or FA biomarkers in salmon, potentially due to aqueous uptake, biotransformation and elimination of the pesticide, or indistinct biomarker compositions among invertebrates with low and high bifenthrin concentrations. One FA [docosahexaenoic acid (DHA)] and DDX were negatively correlated in salmon, potentially due to a greater uptake of DDX from invertebrates with low DHA or effects of DDX on FA metabolism. Trophic biomarkers may be useful indicators of DDX accumulation and effects in juvenile Chinook Salmon in the Sacramento River Delta.

Impact of Perinatal Coexposure to Chlorpyrifos and a High-Fat Diet on Kisspeptin and GnRHR Presence and Reproductive Organs

Emerging evidence has indicated the involvement of extrahypothalamic Kisspeptin and GnRHR in reproductive function. In this study, we evaluate if maternal exposure to the pesticide chlorpyrifos (CPF) and/or a high-fat diet (HFD) has an impact on the expression of Kisspeptin and GnRHR in the reproductive organs of rats' offspring. A total of 16 pregnant rats are divided into four groups: a control group (n = 4), CPF group (4 rats exposed daily to 1/mg/kg/day), HFD group (4 rats randomly fed a 5.25 kcal/g HFD), and coexposed group (4 rats exposed to CPF and HDF). At postnatal development postnatal day (PND) 60, male and female offspring were sacrificed. The reproductive organs (ovary and testis) were removed, and histological and immunohistological analysis and in silico quantification (TissueGnostics software 6.0.1.102, TissueFAXS, HistoQuest) were applied to investigate the impact of different treatments on Kisspeptin and GnRHR expression in reproductive organs. The main outcomes of the study showed a significant decrease in rat offspring's body weight in the CPF group from PND30 and PND60 (p < 0.05 and p < 0.01, respectively). Histological analysis showed a significant increase in the atretic follicle and abnormal testis structure with germ cell desquamation in the CPF-exposed group. The immunodetection quantification of protein shows a significant decrease in GnRHR and Kisspeptin in the HFD and CPF exposed groups, respectively, in testis rat offspring. Perinatal exposure to CPF and HFD exposure affect the reproduction function of rat offspring.

Untargeted metabolomics reveals the preventive effect of quercetin on nephrotoxicity induced by four organophosphorus pesticide mixtures

This research aimed to explore the protective effect of quercetin against nephrotoxicity induced by four organophosphate pesticide mixtures (PM) using untargeted metabolomics technology in rat kidneys. Sixty male Wistar rats were randomly divided into six groups: control, low-dose quercetin treated (10 mg/kg. bw), high-dose quercetin treated (50 mg/kg. bw), PM-treated, and two dosages of quercetin + PM-treated. Metabolomics results showed that 17 differential metabolites were identified in the PM-treated group, and pathway analysis revealed that renal metabolic disorders include purine metabolism, glycerophospholipid metabolism, and vitamin B6 metabolism. When high-dose quercetin and PM-treated were administered to rats concurrently, the intensities of differential metabolites were substantially restored (p < 0.01), suggesting that quercetin can improve renal metabolic disorders caused by organophosphate pesticides (OPs). Mechanistically, quercetin could regulate the purine metabolism disorder and endoplasmic reticulum stress (ERS)-mediated autophagy induced by OPs by inhibiting XOD activity. Moreover, quercetin inhibits PLA2 activity to regulate glycerophospholipid metabolism and it could also exert antioxidant and anti-inflammatory effects to correct vitamin B6 metabolism in rat kidneys. Taken together, the high dose of quercetin (50 mg/kg.bw) has a certain protective effect on OPs-induced nephrotoxicity in rats, which provides a theoretical basis for quercetin against nephrotoxicity caused by OPs.

The Use of Non-targeted Lipidomics and Histopathology to Characterize the Neurotoxicity of Bifenthrin to Juvenile Rainbow Trout (Oncorhynchus mykiss)

Due to the detection frequencies and measured concentrations in surface water, the type I pyrethroid insecticide, bifenthrin, has been of particular concern within the Sacramento-San Joaquin Delta in California. Concentrations have been detected above levels previously reported to impair neuroendocrine function and induce neurotoxicity to several species of salmonids. Metabolomic and transcriptomic studies indicated impairment of cellular signaling within the brain of exposed animals and potential alteration of lipid metabolism. To better understand the potential impacts of bifenthrin on brain lipids, juvenile rainbow trout (Oncorhynchus mykiss) were exposed to mean bifenthrin concentrations of 28 or 48 ng/L for 14 days, and non-targeted lipidomic profiling in the brain was conducted. Brain tissue sections were also assessed for histopathological insult following bifenthrin treatment. Bifenthrin-exposed trout had a concentration-dependent decrease in the relative abundance of triglycerides (TGs) with levels of phosphatidylcholines (PCs) and phosphatidylethanolamines (PEs) significantly altered following 48 ng/L bifenthrin exposure. An increased incidence of histopathological lesions, such as focal hemorrhages and congestion of blood vessels, was noted in the brains of bifenthrin-treated animals, suggesting an association between altered lipid metabolism and neuronal cell structure and integrity.

Decarboxylases as hypothetical targets for actions of organophosphates: Molecular modeling for prediction of hidden and unexpected health threats

The rise of various neurodegenerative disorders are somewhat correlating with the worldwide application of multiple anthropogenic toxicants. Though different possible targets were revealed to date, for example, for organophosphorus compounds (OPs), plenty of questions remain. Several decarboxylases (aromatic amino acid decarboxylase, AADC; histidine decarboxylase, HDC; glutamate decarboxylase, GAD) catalyze the biosynthesis of neurotransmitters and neuromodulators and contain pyridoxal phosphate (PLP) as a cofactor. In the current work, 18 OPs which have different neurotoxicity (chemical warfare agents and pesticides) and can penetrate through the blood-brain barrier, were selected. Then, their possible interaction with these decarboxylases in both apo- and holoforms was revealed using computer modeling methods (molecular docking and dynamics). The main amino acid residues of the enzymes responsible for binding OPs have been identified. Individual substances that are most dangerous from the point of view of a possible negative effect on the activity of several decarboxylases were revealed among studied OPs. Glyphosate should be of special interest, since it is not highly toxic towards serine hydrolases, but may prove to be a strong inhibitor for decarboxylases. Holo-AADC could be the most inhibition-prone enzyme among all those investigated.

Enhanced trophic transfer of chlorpyrifos from resistant Hyalella azteca to inland silversides (Menidia beryllina) and effects on acetylcholinesterase activity and swimming performance at varying temperatures

Chlorpyrifos, an organophosphate (OP) insecticide, is prevalent in aquatic systems globally and is often implicated in aquatic toxicity during storm events. Chlorpyrifos induces toxicity by inhibition of acetylcholinesterase (AChE) activity, which has been related to alterations to fish swimming performance. Resistance to organophosphate insecticides, including chlorpyrifos, is prevalent in populations of the epibenthic amphipod Hyalella azteca in areas with known OP exposure. Previous studies have demonstrated an elevated bioaccumulation potential of insecticide-resistant prey items, however the potential for trophic transfer of chlorpyrifos from OP-resistant prey items and associated neurotoxic effects in fish predators has not been studied. Consequently, the present study aimed to determine the potential for trophic transfer of chlorpyrifos from OP-resistant H. azteca to a known predator, the inland silverside, Menidia beryllina at two temperatures (18 and 23 °C) to simulate temperature changes associated with global climate change (GCC). Fish were fed either ¹⁴C-chlorpyrifos-dosed H. azteca or control animals for 7 d, after which total bioaccumulation, percent parent chlorpyrifos, brain AChE activity and swimming performance (ramp-U_crit) were determined. Fish fed chlorpyrifos-dosed H. azteca bioaccumulated chlorpyrifos ranging from 29.9 to 1250 ng/g lipid, demonstrating the potential for trophic transfer. Lower bioaccumulation and greater biotransformation were observed in M. beryllina at 23 °C as compared to 18 °C, though this was not statistically significant. A significant 36.5% reduction in brain AChE activity was observed in fish fed chlorpyrifos-dosed H. azteca at 23 °C only, which may be attributed to increased biotransformation of parent chlorpyrifos to more potent AChE-inhibiting metabolites. Dietary chlorpyrifos exposure had no significant effect on swimming performance in M. beryllina, though ramp-U_crit was significantly increased by 25% at 23 as compared to 18 °C. These findings confirm the potential for trophic transfer of chlorpyrifos from OP-resistant prey to fish predators and the potential for elevated temperatures to exacerbate the neurotoxic effects of chlorpyrifos.

Design of bioluminescent biosensors for assessing contamination of complex matrices

The presence of potentially toxic xenobiotics in complex matrices has become rather the rule than the exception. Therefore, there is a need for highly sensitive inexpensive techniques for analyzing environmental and food matrices for toxicants. Enzymes are selectively sensitive to various toxic compounds, and, thus, they can be used as the basis for detection of contaminants in complex matrices. There are, however, a number of difficulties associated with the analysis of complex matrices using enzyme assays, including the necessity to take into account properties and effects of the natural components of the test media for accurate interpretation of results. The present study describes the six-stage procedure for designing new enzyme sensors intended for assessing the quality of complex matrices. This procedure should be followed both to achieve the highest possible sensitivity of the biosensor to potentially toxic substances and to minimize the effect of the uncontaminated components of complex mixtures on the activity of the biosensor. The proposed strategy has been tested in designing a bioluminescent biosensor for integrated rapid assessment of the safety of fruits and vegetables. The biosensor is based on the coupled enzyme system NAD(P)H:FMN-oxidoreductase and luciferase as the biorecognition element. The study describes methods and techniques for attaining the desired result in each stage. The proposed six-stage procedure for designing bioluminescent enzyme biosensors can be used to design the enzymatic biosensors based on other enzymes.

Vitamin C rescues inflammation, immunosuppression, and histopathological alterations induced by chlorpyrifos in Nile tilapia

Chlorpyrifos (CPF) is an extensive environmental contaminant and disrupts the physiological status of living organisms. CPF is found to hinder the health of aquatic organisms and ecological function in aquatic systems. The current study aimed at evaluating the protective effects of vitamin C (VC) on the immune response, hematological parameters, and histopathological alterations in Nile tilapia exposed to CPF. Nile tilapia were exposed to waterborne CPF (15 μg/L) for 30 days. Fish were divided into control group: received basal diet; CPF group: received basal diet and exposed to waterborne CPF; VC group: received basal diet plus 0.8 mg VC/kg; and CPF/VC group: received basal diet plus 0.8 mg VC/kg and exposed to waterborne CPF. Blood samples were taken after 15 days and 30 days of the treatment. Liver, gills, and intestine tissues were collected on the 30th day of treatment. CPF showed a deleterious effect on fish's growth performance; it decreased the weight gain by 6%, while VC increased it by 17-23% compared to the control group. CPF group recorded the lowest survival rate (83%), while VC achieved survivability of 96.7% and 93.3% in VC and CPF/VC groups, respectively. The blood picture revealed moderate changes in the CPF group, where the marked alteration was in the hemoglobin concentration and white blood cells. CPF disrupted the hepatic and renal function. Serum lysozyme activity, phagocytic activity, and phagocytic index displayed a dramatic decline in the CPF group but enhanced in VC and CPF/VC groups. An upregulation was observed in antioxidant genes (catalase and glutathione peroxidase), heat shock protein 70, caspase-3, and the cytokines interleukin 1β, interleukin 8, and interferon-gamma in the CPF group. Simultaneously, moderate or normal levels were shown in the VC and CPF/VC groups. CPF altered the histoarchitecture of gills, intestine, and hepatopancreas with apparent degenerative changes possibly resulted from the oxidative stress. At the same time, VC retained the normal structure of the studied tissues. This study raises concerns about the safety of CPF and its impact on the aquatic environment. VC has a high potential to restore the normal physiology of fish exposed to CPF.

A comprehensive review on chlorpyrifos toxicity with special reference to endocrine disruption: Evidence of mechanisms, exposures and mitigation strategies

Chlorpyrifos (CPF) is a broad-spectrum chlorinated organophosphate (OP) pesticide used for the control of a variety of insects and pathogens in crops, fruits, vegetables, as well as households, and various other locations. The toxicity of CPF has been associated with neurological dysfunctions, endocrine disruption, and cardiovascular diseases (CVDs). It can also induce developmental and behavioral anomalies, hematological malignancies, genotoxicity, histopathological aberrations, immunotoxicity, and oxidative stress as evidenced by animal modeling. Moreover, eye irritation and dermatological defects are also reported due to CPF toxicity. The mechanism of action of CPF involves blocking the active sites of the enzyme, acetylcholinesterase (AChE), thereby producing adverse nervous system effects. Although CPF has low persistence in the body, its active metabolites, 3,5,6-trichloro-2-pyridinol (TCP), and chlorpyrifos-oxon (CPO) are comparatively more persistent, albeit equally toxic, and thus produce serious health complications. The present review has been compiled taking into account the work related to CPF toxicity and provides a brief compilation of CPF-induced defects in animals and humans, emphasizing the abnormalities leading to endocrine disruption, neurotoxicity, reproductive carcinogenesis, and disruptive mammary gland functionality. Moreover, the clinical signs and symptoms associated with the CPF exposure along with the possible pharmacological treatment are reported in this treatise. Additionally, the effect of food processing methods in reducing CPF residues from different agricultural commodities and dietary interventions to curtail the toxicity of CPF has also been discussed.

In Silico Studies of Lamiaceae Diterpenes with Bioinsecticide Potential against Aphis gossypii and Drosophila melanogaster

Background: The growing demand for agricultural products has led to the misuse/overuse of insecticides; resulting in the use of higher concentrations and the need for ever more toxic products. Ecologically, bioinsecticides are considered better and safer than synthetic insecticides; they must be toxic to the target organism, yet with low or no toxicity to non-target organisms. Many plant extracts have seen their high insecticide potential confirmed under laboratory conditions, and in the search for plant compounds with bioinsecticidal activity, the Lamiaceae family has yielded satisfactory results. Objective: The aim of our study was to develop computer-assisted predictions for compounds with known insecticidal activity against Aphis gossypii and Drosophila melanogaster. Results and conclusion: Structure analysis revealed ent-kaurane, kaurene, and clerodane diterpenes as the most active, showing excellent results. We also found that the interactions formed by these compounds were more stable, or presented similar stability to the commercialized insecticides tested. Overall, we concluded that the compounds bistenuifolin L (1836) and bistenuifolin K (1931), were potentially active against A. gossypii enzymes; and salvisplendin C (1086) and salvixalapadiene (1195), are potentially active against D. melanogaster. We observed and highlight that the diterpenes bistenuifolin L (1836), bistenuifolin K (1931), salvisplendin C (1086), and salvixalapadiene (1195), present a high probability of activity and low toxicity against the species studied.

Lipidomics reveals multiple stressor effects (temperature × mitochondrial toxicant) in the zebrafish embryo toxicity test

Aquatic organisms are exposed to multiple stressors in the environment, including contaminants and rising temperatures due to climate change. The objective of this study was to characterize the effect of increased temperature on chemical-induced toxicity and lipid profiles during embryonic development and hatch in fish. This is important because temperature and many environmental chemicals modulate cellular metabolism and lipids, both of which play integral roles for normal embryonic development. As such, we employed the zebrafish embryo toxicity test for multiple stressor exposures, using the mitochondrial toxicant 2,4-Dinitrophenol (DNP; 6-30 μM) in conjunction with different temperature treatments (28 °C and 33 °C). We found a positive relationship between temperature and lethality at lower DNP concentrations, suggesting temperature stress can increase toxicant sensitivity. Next, we used LC-MS/MS for lipidomics following exposure to sublethal stressor combinations. It was determined that temperature stress at 33 °C augmented DNP-induced effects on the lipidome, including the upregulation of bioactive lipids involved in apoptosis (e.g., ceramides). These data reveal potential implications for climate change and sensitivity to environmental pollution and demonstrate the utility of lipidomics to characterize metabolic pathways underlying toxicity. Data such as these are expected to advance adverse outcome pathways by establishing multiple stressor networks that include intermediate lipid responses.

Metabolomic Profiles in the Brains of Juvenile Steelhead (Oncorhynchus mykiss) Following Bifenthrin Treatment

The pyrethroid insecticide, bifenthrin, is frequently measured at concentrations exceeding those that induce acute and chronic toxicity to several invertebrate and fish species residing in the Sacramento-San Joaquin Delta of California. Since the brain is considered to be a significant target for bifenthrin toxicity, juvenile steelhead trout (Oncorhynchus mykiss) were treated with concentrations of bifenthrin found prior to (60 ng/L) and following (120 ng/L) major stormwater runoff events with nontargeted metabolomics used to target transcriptomic alterations in steelhead brains following exposure. Predicted responses were involved in cellular apoptosis and necrosis in steelhead treated with 60 ng/L bifenthrin using the software Ingenuity Pathway Analysis. These responses were predominately driven by decreased levels of acetyl-l-carnitine (ALC), docosahexaenoic acid (DHA), and adenine. Steelhead treated with 120 ng/L bifenthrin had reductions of lysophosphatidylcholines (LPC), lysophosphatidylethanolamines (LPE), and increased levels of betaine, which were predicted to induce an inflammatory response. Several genes predicted to be involved in apoptotic (caspase3 and nrf2) and inflammatory (miox) pathways had altered expression following exposure to bifenthrin. There was a significantly increased expression of caspase3 and miox in fish treated with 120 ng/L bifenthrin with a significant reduction of nrf2 in fish treated with 60 ng/L bifenthrin. These data indicate that bifenthrin may have multiple targets within the brain that affect general neuron viability, function, and signaling potentially through alterations in signaling fatty acids.

Ecotoxico-lipidomics: An emerging concept to understand chemical-metabolic relationships in comparative fish models

Lipids play an essential role in development, homeostatic functions, immune signaling, reproduction, and growth. Although it is evident that changes in lipid biosynthesis and metabolism can affect organismal physiology, few studies have determined how environmental stressors affect lipid pathways, let alone alter global lipid profiles in fish. This is a significant research gap, as a number of environmental contaminants interact with lipid signaling and metabolic pathways. In this review, we highlight the utility of lipidomics as a tool in environmental toxicology, discussing the current state of knowledge regarding chemical-lipidomic perturbations. As with most oviparous animals, the processing and storage of lipids during oocyte development is also particularly important for embryogenesis in fish. Using largemouth bass (Micropterus salmoides) as an example, transcriptomics data suggest that various chemicals alter lipid metabolism and regulation, highlighting the need for more sophisticated investigations into how toxicants impact lipid responses. We also point out the challenges ahead; these include a lack of understanding about lipid processing and signaling in fish, tissue and species-specific lipid composition, and extraneous factors (e.g., nutrition, temperature) that confound interpretation. For example, toxicant exposure can lead to oxidative stress and lipid peroxidation, resulting in complex lipid byproducts that are challenging to measure. With the emergence of lipidomics in systems toxicology, multi-omics approaches are expected to more clearly define effects on physiology, creating stronger linkages between multiple molecular entities (gene-protein-lipid/metabolite). The development and implementation of novel technologies such as ion mobility-mass spectrometry and ozone-induced dissociation support the complete structural elucidation of lipid molecules. This has implications in the adverse outcome pathway framework, which will enhance the application of lipidomics in toxicology by linking these molecular changes to effects at higher levels of biological organization.