Sublethal toxicity of quinalphos on oxidative stress and antioxidant responses in a freshwater fish Cyprinus carpio

Unveiling the impact of bisphenol A on date mussels: Insights into oxidative stress, hormonal imbalance, gonadal atresia, and immune resilience

Sedentary organisms, such as mussels, may be susceptible to environmental estrogenic compounds, including bisphenol A (BPA). This study aimed to evaluate the interplay between BPA exposure and the immune response, hormonal imbalance, tissue damage (specifically in the digestive glands, labial palps, and male gonads), gonadal atresia, and antioxidant mechanisms in the marine mussel, Lithophaga lithophaga. Over a period of 28 days, mussels were exposed to BPA concentrations of 0, 0.25, 1, 2, and 5 μg/L. The exposure resulted in notable morphological alterations in the hemocytes of L. lithophaga, characterized by irregularities in the outer cell membranes of granulocytes and hyalinocytes, with some cells exhibiting filopodia formation. Granulocytes displayed an increased number of granules and vacuoles, while the nuclei of hyalinocytes appeared shrunken. The condition index, along with levels of testosterone and 17β-estradiol, significantly decreased with increasing BPA concentration, except for the 1 and 2 μg/L treatments. BPA exposure led to a marked increase in malondialdehyde (MDA) levels and a reduction in reduced glutathione (GSH) across all tissues at every concentration tested. The activity of antioxidant enzymes varied among the gonads, digestive glands, and labial palps. Notably, there was a significant increase in superoxide dismutase (SOD) activity in the gonads of mussels exposed to 2 μg/L of BPA, as well as in the digestive glands and labial palps of those exposed to 1 μg/L, suggesting a potential alteration in redox homeostasis. Additionally, structural changes in the digestive tubules of BPA-exposed mussels were observed. The observed pathological symptoms were characteristic of an inflammatory response, including hemocyte diapedesis and infiltration, the formation of syncytia, and the sloughing of epithelial tissue, indicated by an increased ratio of mean luminal radius to mean epithelial thickness in a dose-dependent manner. In the BPA-exposed group, testicular follicles exhibited atrophy, deformation, and a reduction in both size and number per area, appearing nearly empty and lacking spermatids and spermatozoa, alongside hypertrophy and hyperplasia of auxiliary cells. Scanning electron microscopy further revealed structural abnormalities in the heads and flagella of spermatids from the BPA-exposed group. Thus, this study demonstrates the risk of long-term exposure to BPA in immune response, tissue, and biochemical responses of date mussel L. lithophaga. The gonad was the most affected tissues followed by the digestive gland and labial palps.

Assessing the dual toxicity of HfO2 nanoparticles and quinalphos on Pila virens

Pila virens (P. virens) is an edible freshwater snail, widely distributed in Asia and Africa. P. virens is used as one of the most promising model organisms for monitoring environmental contamination in aquatic ecosystems. The physiological responses to the contaminants such as pesticides and nanomaterials are inadequate, especially in relation to the effects of co-exposure. In this work, we have investigated on the noxious effects of co-exposure between an organophosphorus pesticide, quinalphos and hafnium oxide nanoparticles (HfO2NPs) on the antioxidant responses of P. virens. Phase pure forms of HfO2NPs (monoclinic, P21/c) were obtained by sol-gel method. The crystallinity, structure and surface morphology were analysed with various spectroscopic methods like powder X-ray, Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), High Resolution Scanning Electron Microscope (HR-SEM) and Transmission Electron Microscope (TEM). P. virens after exposure for 96 h to the different concentrations of quinalphos (0.25-2.25 mg/mL) and HfO2NPs (10-50 mg/mL), the median lethal concentration (LC50) was determined to be 1.159 mg/mL and 11.47 mg/mL, respectively and show a significant fatal effect against the snail. The P. virens were exposed to sub-lethal concentrations of LC25 (0.57 mg/mL quinalphos and 5.73 mg/mL HfO2NPs) individually and in combination as a binary toxicity (quinalphos + HfO2NPs), (0.57 mg/mL + 5.73 mg/mL) for 24 and 48 h. Further, the antioxidant responses were assessed which included catalase (CAT), glutathione sulfo-transferase (GST), and malonaldehyde (MDA) activity in the group exposed to quinalphos and HfO2NPs exhibited to show an enhancement in their activity in comparison to controls after 24 and 48 h and revealed that 48 h exposure has significant impact. These results provide a valuable insight towards increased awareness of the physiological defences of P. virens after co-exposure to quinalphos and HfO2NPs in aquatic ecosystem.

Sub-Chronic Methomyl Exposure Induces Oxidative Stress and Inflammatory Responses in Zebrafish with Higher Female Susceptibility

The widespread use of carbamate pesticides has raised significant environmental and health concerns, particularly regarding water contamination and the disruption of defense systems in organisms. Despite these concerns, research on the differential impacts of pesticides on male and female organisms remains limited. This study focused on methomyl, investigating sex-specific differences in liver antioxidant defenses and inflammatory response indices in male and female zebrafish after 56 days of exposure to environmentally relevant concentrations (0, 0.05, 0.10, and 0.20 mg/L). Our findings indicate that methomyl exposure significantly increased ROS content in zebrafish livers, inducing oxidative stress and activating enzymatic antioxidant defenses such as SOD, CAT, and GSH-Px activities. Sub-chronic exposure altered the expression of apoptosis-related genes (Bax/Bcl2a and Caspases3a), resulting in liver cell apoptosis in a concentration-dependent manner, with the 0.20 mg/L concentration causing the most severe damage. Additionally, methomyl exposure at environmentally relevant concentrations triggered persistent inflammatory responses in liver tissues, evidenced by increased transcription levels of inflammatory factor genes and the activation of toll-like receptors, heightening susceptibility to exogenous allergens. It is noteworthy that oxidative damage indicators (AST, ROS, MDA) and inflammatory gene expressions (IL-1β, TNF-α) were significantly higher in female livers compared to male livers at 0.10-0.20 mg/L methomyl exposure. Consequently, our study underscores the potential adverse effects of environmental methomyl exposure on aquatic organisms and highlights the need for heightened consideration of the risks posed by environmental endocrine disruptors to female health and safety.

New roles for Bacillus thuringiensis in the removal of environmental pollutants

For a long time, the well-known Gram-positive bacterium Bacillus thuringiensis (Bt) has been extensively studied and developed as a biological insecticide for Lepidoptera and Coleoptera pests due to its ability to secrete a large number of specific insecticidal proteins. In recent years, studies have found that Bt strains can also potentially biodegrade residual pollutants in the environment. Many researchers have isolated Bt strains from multiple sites polluted by exogenous compounds and characterized and identified their xenobiotic-degrading potential. Furthermore, its pathway for degradation was also investigated at molecular level, and a number of major genes/enzymes responsible for degradation have been explored. At present, a variety of xenobiotics involved in degradation in Bt have been reported, including inorganic pollutants (used in the field of heavy metal biosorption and recovery and precious metal recovery and regeneration), pesticides (chlorpyrifos, cypermethrin, 2,2-dichloropropionic acid, etc.), organic tin, petroleum and polycyclic aromatic hydrocarbons, reactive dyes (congo red, methyl orange, methyl blue, etc.), and ibuprofen, among others. In this paper, the biodegrading ability of Bt is reviewed according to the categories of related pollutants, so as to emphasize that Bt is a powerful agent for removing environmental pollutants.

Chronic exposure to bisphenol A induces behavioural, neurochemical, histological, and ultrastructural alterations in the ganglia tissue of the date mussels Lithophaga lithophaga

Bisphenol A (BPA), a common plastic additive, has been demonstrated mechanistically to be a potential endocrine disruptor and to affect a variety of body functions in organisms. Although previous research has shown that BPA is toxic to aquatic organisms, the mechanism of neurotoxic effects in marine bivalves remains unknown. The current study aimed to elucidate the neurotoxic effects of BPA when administered at different concentrations (0.25, 1, 2, and 5 µg/L) for twenty-eight days in the ganglia of a bivalve model, the Mediterranean mussel (Lithophaga lithophaga), which is an ecologically and economically important human food source of bivalve species in the Mediterranean Sea. Our findings revealed an increase in behavioural disturbances and malondialdehyde levels in treated mussel ganglia compared to the control group. Furthermore, superoxide dismutase activity increased in the ganglia of L. lithophaga treated with 0.25 and 2 µg/L. However, at BPA concentrations of 1 and 5 µg/L, SOD activity was significantly reduced, as was total glutathione concentration. BPA causes neurotoxicity, as evidenced by concentration-dependent inhibition of acetylcholinesterase, dopamine, and serotonin. After chronic exposure to BPA, neurons showed distortion of the neuronal cell body and varying degrees of pyknosis. The ultrastructure changes in BPA-treated groups revealed the lightening of the nucleoplasm and a shrunken nuclear envelope. Overall, our findings suggest that BPA exposure altered antioxidation, neurochemical biomarkers, histopathological, and ultrastructural properties, resulting in behavioural changes. As a result, our findings provide a basis for further study into the toxicity of BPA in marine bivalves.

Cyhalofop-butyl and pyribenzoxim-induced oxidative stress and transcriptome changes in the muscle of crayfish (Procambarus clarkii)

Cyhalofop-butyl and pyribenzoxim are commonly used herbicides in rice-crayfish co-culture fields. In actual production, weed control in paddy fields is inseparable from cyhalofop-butyl and pyribenzoxim, while its risk to P. clarkii is still unclear. The present study investigated the risk of acute and subchronic toxicity of cyhalofop-butyl and pyribenzoxim to P. clarkii. The results showed that cyhalofop-butyl and pyribenzoxim exposure for 28 days could accumulate in P. clarkii muscle and inhibit P. clarkii growth. Further research found that the malondialdehyde (MDA) level and glutathione-S-transferase (GST) activity in muscle of P. clarkii were significantly increased after exposure to cyhalofop-butyl and pyribenzoxim (4 days and 28 days), and the superoxide dismutase (SOD) and catalase (CAT) activities were significantly altered. Histological results also confirmed cyhalofop-butyl and pyribenzoxim-induced muscle damage in P. clarkii. Additionally, after 28 days exposure to 1.02 mg/L cyhalofop-butyl and 10.4 mg/L pyribenzoxim, transcriptome analysis identified 2029 and 4246 differentially expressed genes (DEGs), respectively. Exposure to 1.02 mg/L cyhalofop-butyl significantly altered metabolism-related pathways, such as drug metabolism-other enzymes, glutathione metabolism, drug metabolism-cytochrome P450, fatty acid biosynthesis and fatty acid degradation. While the pathways related to antioxidant system and nutrient substances synthesis and metabolic were significantly enriched after exposure to 10.4 mg/L pyribenzoxim. This research has significant implications for scientific and rational use of herbicides under rice-crayfish co-culture and will contribute to the development of the highly productive agricultural model.

Assessing the toxic effects of bisphenol A in consumed crayfish Astacus leptodactylus using multi biochemical markers

Bisphenol A (BPA), an endocrine-disrupting chemical (EDC), has strong potential for daily exposure to humans and animals due to its persistence and widespread in the environment, so its effects directly concern public health. Although invertebrates represent important components of aquatic ecosystems and are at significant risk of exposure, there is little information about the biological effects of EDCs in these organisms. Astacus leptodactylus used in this study is one of the most consumed and exported freshwater species in Europe. In this study, the 96-h effect of BPA on A. leptodactylus was examined using various biomarkers. The LC₅₀ value of BPA was determined as 96.45 mg L^-1. After 96 h of exposure to BPA, there were increases in superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione S-transferase (GST), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) activities and levels of malondialdehyde (MDA), and total oxidant status context (TOSC), and there were decreases in the activity of glutathione reductase (GR), carboxylesterase (CaE), acetylcholinesterase (AChE), Na⁺/K⁺ ATPase, Mg²⁺ ATPase, Ca²⁺ ATPase, and total ATPase and the total antioxidant context (TAC). From the results of this study, it can be concluded that BPA has significant toxic effects on A. leptodactylus based on the selected biochemical parameters of antioxidant, cholinergic, detoxification, and metabolic systems in crayfish even at low doses. Thus, it can be said that BPA can seriously threaten the aquatic ecosystem and public health.

Advances in organophosphorus pesticides pollution: Current status and challenges in ecotoxicological, sustainable agriculture, and degradation strategies

Organophosphorus pesticides (OPPs) are one of the most widely used types of pesticide that play an important role in the production process due to their effects on preventing pathogen infection and increasing yield. However, in the early development and application of OPPs, their toxicological effects and the issue of environmental pollution were not considered. With the long-term overuse of OPPs, their hazards to the ecological environment (including soil and water) and animal health have attracted increasing attention. Therefore, this review first clarified the classification, characteristics, applications of various OPPs, and the government's restriction requirements on various OPPs. Second, the toxicological effects and metabolic mechanisms of OPPs and their metabolites were introduced in organisms. Finally, the existing methods of degrading OPPs were summarized, and the challenges and further addressing strategy of OPPs in the sustainable development of agriculture, the environment, and ecology were prospected. However, methods to solve the environmental and ecological problems caused by OPPs from the three aspects of use source, use process, and degradation methods were proposed, which provided a theoretical basis for addressing the stability of the ecological environment and improving the structure of the pesticide industry in the future.

Eliminating pesticide quinalphos from surface waters using synthesized GO-ZnO nanoflowers: Characterization, degradation pathways and kinetic study

The presence of highly toxic and persistent pesticides in water bodies causes serious problems to human beings as well as aquatic life. Quinalphos is one such widely used organophosphorus pesticide in agricultural fields. Herein, for degradation and mineralization of quinalphos, ZnO nanoflowers and their hybrid nanocomposite with graphene oxide have been synthesized. FESEM analysis confirmed the formation of ZnO nanoflowers over nanosheets of graphene oxide having a thickness of 20 ± 10 nm. GO-ZnO composite exhibited remarkable photocatalytic activity in comparison to pure ZnO. 98 % degradation of quinalphos was achieved using GO-ZnO nano-catalyst at 6 pH within 45 min of irradiations, whereas it was 80 % for bare ZnO nanoflowers. Higher degradation with hybrid nanocomposite was attributed to improved surface area (36 m² g^-1), a substantial reduction in bandgap energy from 3.10 to 2.90 eV and enhanced charge separation (e^-/h⁺ pairs) after the addition of GO. Reaction kinetics study followed pseudo-first-order behaviour. Further, mineralization to the extent of 90 % in 90 min was confirmed by TOC analysis. Based on identified intermediates, using LCMS analysis, degradation pathways were proposed. The plausible pathways confirmed the presence of smaller and safer reaction intermediates supported by excitation of e^- from nanocomposite followed by oxidation of quinalphos with huge free radicals. Overall, this study is significant in terms of using photocatalysis as a tertiary treatment of quinalphos pesticide wastewater at pH 6 in a short duration.

Antioxidant and Protective Effects of Artemisia campestris Essential Oil Against Chlorpyrifos-Induced Kidney and Liver Injuries in Rats

This study is aimed to elucidate the possible antioxidant and protective effects of Artemisia campestris essential oil (ACEO) against the deleterious effects of chlorpyrifos (CPF) in rats. The in vivo study revealed increases in aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and alkaline phosphatase (ALP) activities and the serum contents of creatinine, urea, uric acid, cholesterol, triglycerides, low density lipoproteins (LDL), and glucose in rats treated with CPF as compared to controls. Meanwhile, hepatic and renal activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in liver and kidney decreased and the content of malondialdehyde (MDA) increased. Some histopathologic features were noticed in liver and kidney of the CPF group. Interestingly, ACEO alleviated the biochemical disruptions and reduced these hepato-renal morphologic changes.

Maximum contaminant level of arsenic in drinking water potentiates quinalphos-induced renal damage on co-administration of both arsenic and quinalphos in Wistar rats

This study was designed to determine alterations in renal biomarkers, antioxidant profile, and histomorphology of renal tissue following subacute exposure to quinalphos alone or in conjunction with arsenic in rats. A total of 54 adult Wistar rats were randomly divided into nine groups of six rats each and were administered sub-lethal concentrations of quinalphos (1/100th and 1/10th of LD50) orally daily and arsenic (50 and 100 ppb) in drinking water for 28 days. Significantly (p < 0.05) decreased levels of antioxidant biomarkers in renal tissue, viz., total thiols, catalase, superoxide dismutase, glutathione peroxidase, glutathione-s-transferase, and glutathione reductase along with increased (p < 0.05) thiobarbituric acid reacting substance (TBRAS) levels indicated that significant oxidative damage to renal tissue occurred following repeated administrations of quinalphos at either dose levels or arsenic at the concentration of 100 ppb when compared with the control rats. The alterations in the antioxidant parameters were observed to be more pronounced in co-administered groups as compared with either toxicant administered group. Similarly, activity of renal acetylcholinesterase was decreased after repeated exposure to quinalphos or arsenic, but inhibition was higher (up to 48%) in rat renal tissue co-exposed with quinalphos and arsenic at the higher concentration. These findings corroborated with the histopathological alterations in renal tissue of toxicant exposed rats. The altered plasma and tissue antioxidant biomarkers along with histopathological changes in the kidney at higher dose level of either toxicant indicate that renal tissue is significantly impacted by these toxicants, and these effects become more pronounced after their co-administration.

DNA damage and physiological responses in an Indian major carp Labeo rohita exposed to an antimicrobial agent triclosan

This study is aimed to evaluate the toxic effects of triclosan (TCS) in an Indian major carp Labeo rohita. The 96-h LC₅₀ value of triclosan to L. rohita was found to be 0.39 mg L^-1. Fish were exposed to two sublethal concentrations (0.039 mg L^-1, treatment I and 0.078 mg L^-1, treatment II) of TCS for 35 days, and certain hematobiochemical, antioxidant, histopathological responses were measured. Compared to the control group, there was a significant (p < 0.05) decrease in the values and genotoxicity of hematological parameters such as hemoglobin (Hb), hematocrit (Hct), and erythrocyte (RBC) in TCS-exposed fish, but the values of leucocyte count (WBC), mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCH) were found to be increased. A biphasic response in mean corpuscular hemoglobin concentration (MCHC) value was observed during the study period (35 days). Significant (p < 0.05) alterations in plasma biochemical parameters (glucose and protein), electrolytes (Na⁺, K⁺, and Cl^-), and transaminases (GOT and GPT) were observed in fish treated with TCS in both treatments. Gill Na⁺/K⁺-ATPase activity was found to be decreased in fish treated with TCS in both treatments. Enzymatic and nonenzymatic antioxidant index levels have also fluctuated in all the tissues (gill, liver, and kidney). The histological lesions were comparatively more severe in the gill than the liver and kidney. Comet assay showed DNA damage on exposure at two sublethal concentrations. The present results suggest that TCS is highly toxic to fish even at sublethal concentrations.

Transcriptomic responses of the clam Meretrix meretrix to the organophosphorus pesticide (dimethoate)

Organophosphorus pesticides (OPs) play a certain role in promoting the development of agriculture and forestry, but they may cause potential harm to aquatic life when entering rivers and polluting water sources. Previous researches have shown that OPs participate in the regulation mechanism of aquatic organisms. Here, our aim is to determine the underlying mechanisms of one OP (dimethoate) at the transcriptional level using the clam Meretrix meretrix. 4119 DEGs were obtained from high-throughput RNA sequencing data. Then, expression profiles of some genes were verified by qPCR, which showed a positive correlation with the RNA sequencing results. 14,481 simple sequence repeats were also identified and could be further used as molecular markers. In addition, some oxidative, immune, and stress-related genes were further discussed and could also be used as biomarkers to indicate the biological response of dimethoate. This study will help to better understand the clam's response mechanism to dimethoate stress.

Evaluating the protective efficacy of Silybum marianum against deltamethrin induced hepatotoxicity in piscine model

With the known facts of deltamethrin toxicity in aquaculture, efforts have been made to ameliorate its toxicity with supplementation of Silybum marianum plant extract in Cyprinus carpio. For validating its efficacy, standard techniques of histopathology, anti-oxidant profile and RAPD-PCR were used. By performing acute toxicity bioassay, 96 h LC50 of the pesticide to C. carpio was determined and was found to be 2 μg/L. Histopathological alterations were comprised of nuclear alterations, vacuolisation and oedema in the hepatocytes. Chronic exposure to the toxicant induced significant changes in antioxidant defense system (CAT, SOD, GSH and GST levels), lipid peroxidation being prominent. Diet supplementation with silymarin appeared to modulate the oxidative stress, histopathological alterations and genotoxic damage caused by the pesticide in the fish. RAPD-PCR studies revealed deltamethrin induced toxicity and its effective amelioration in form of restoration of bands which were lost in toxicant exposed DNA profile.

Chronic exposure to quinalphos shows biochemical changes and genotoxicty in erythrocytes of silver barb, Barbonymus gonionotus

An in vivo study was carried out on the freshwater fish Barbonymus gonionotus to evaluate the genotoxic effects of the organophosphate quinalphos. The fish were exposed to sub-lethal doses of quinalphos (0%, 10%, 25%, and 50% of LC₅₀) for a period of 30 days. Analysis of biochemical characteristics (protein and lipid contents of different organs), nuclear abnormalities of erythrocytes (NAE) and morphological abnormalities of erythrocytes (MAE) were performed on peripheral erythrocytes sampled at post-treatment intervals of 0 and 30 days. The biochemical results revealed a significant dose-dependent decline in protein and lipid contents and increase in the frequencies of NAE as well as MAE. Our findings also confirmed that the morphological deformations of erythrocytes in addition to NAE on fish erythrocytes in vivo are effective tools in determining the potential genotoxicity of organophosphates.

Oxidative stress and DNA damage in common carp (Cyprinus carpio) exposed to the herbicide mesotrione

The present study was undertaken to investigate the oxidative stress and genotoxic effects of the herbicide mesotrione in a common freshwater fish, Cyprinus carpio. These fish were exposed to environmentally relevant concentrations of mesotrione (1.8, 18 and 180 μg L^-1) for 7, 14 and 28 days. Levels of reactive oxygen species (ROS), malondialdehyde (MDA), reduced glutathione (GSH), activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) were measured in the gill, liver and muscle, together with levels of DNA damage that occurred. After 28 days exposure, significant increases in SOD and CAT activity and ROS content were observed in all three tissues but only at the highest concentration of exposure (180 μg L^-1). No obvious changes in MDA, GSH, GPx or GR were observed in all treatments during the experiment. Comet assays revealed that the highest concentration of mesotrione induced DNA damage to different tissues in the common carp, especially the liver after chronic exposure occurred. These results provide evidence that the oxidant-antioxidant and comet assay could be integrated into monitoring programs determining the toxicity of water pollutants.