Evaluation of the acute toxic effect of azoxystrobin on non-target crayfish (Astacus leptodactylus Eschscholtz, 1823) by using oxidative stress enzymes, ATPases and cholinesterase as biomarkers

Oxidative stress and DNA alteration on the earthworm Eisenia fetida exposed to four commercial pesticides

Modern agriculture is mainly based on the use of pesticides to protect crops but their efficiency is very low, in fact, most of them reach water or soil ecosystems causing pollution and health hazards to non-target organisms. Fungicide triazoles and strobilurins based are the most widely used and require a specific effort to investigate toxicological effects on non-target species. This study evaluates the toxic effects of four commercial fungicides Prosaro® (tebuconazole and prothioconazole), Amistar®Xtra (azoxystrobin and cyproconazole), Mirador® (azoxystrobin) and Icarus® (Tebuconazole) on Eisenia fetida using several biomarkers: lipid peroxidation (LPO), catalase activity (CAT), glutathione S-transferase (GST), total glutathione (GSHt), DNA fragmentation (comet assay) and lysozyme activity tested for the first time in E. fetida. The exposure to Mirador® and AmistarXtra® caused an imbalance of ROS species, leading to the inhibition of the immune system. AmistarXtra® and Prosaro®, composed of two active ingredients, induced significant DNA alteration, indicating genotoxic effects. This study broadened our knowledge of the effects of pesticide product formulations on earthworms and showed the need for improvement in the evaluation of toxicological risk deriving from the changing of physicochemical and toxicological properties that occur when a commercial formulation contains more than one active ingredient and several unknown co-formulants.

Environmental levels of azoxystrobin disturb male zebrafish behavior: Possible roles of oxidative stress, cholinergic system, and dopaminergic system

A widely applied pesticide of azoxystrobin, is increasingly detected in the water environment. Concern has been raised against its potential detriment to aquatic ecosystems. It has been shown that exposure to azoxystrobin interfere with the locomotor behavior of zebrafish larvae. This study aims to investigate whether exposure to environmental levels of azoxystrobin (2 μg/L, 20 μg/L, and 200 μg/L) changes the behavior of male adult zebrafish. Herein, we evaluated behavioral response (locomotor, anxiety-like, and exploratory behaviors), histopathology, biochemical indicators, and gene expression in male adult zebrafish upon azoxystrobin exposure. The study showed that exposure to azoxystrobin for 42 days remarkably increased the locomotor ability of male zebrafish, resulted in anxiety-like behavior, and inhibited exploratory behavior. After treatment with 200 μg/L azoxystrobin, vasodilatation, and congestion were observed in male zebrafish brains. Exposure to 200 μg/L azoxystrobin notably elevated ROS level, MDA concentration, CAT activity, and AChE activity, while inhibiting SOD activity, GPx activity, ACh concentration, and DA concentration in male zebrafish brains. Moreover, the expression levels of genes related to the antioxidant, cholinergic, and dopaminergic systems were significantly changed. This suggests that azoxystrobin may interfere with the homeostasis of neurotransmitters by causing oxidative stress in male zebrafish brains, thus affecting the behavioral response of male zebrafish.

Multigenerational and transgenerational effects of azoxystrobin on Folsomia candida

Soil organisms are exposed to various pollutants during several generations. However standard toxicity tests are often based on exposure in only one generation. Research of multigenerational (MG) and transgenerational (TG) effects are still quite scarce, however evidence accumulates that effects observed in one generation can be significantly different in some of the following generations, with different effects observed. Some studies suggest adaptation to pollutants, while others report severe effects in following generations. Azoxystrobin is commonly used in the prevention and treatment of fungal diseases in a wide range of economically important crops. The main aim of this study was to assess the toxic effects of azoxystrobin (AZO) on F. candida over 3 generations through the application of biochemical and population level biomarkers. Results of reproduction tests showed a significant decrease in estimated EC50 values, with EC50 for F0 being estimated at 104.44 mga.i./kgD.W.soil and only 15.4 mga.i./kgD.W.soil for F1. In F1 a significant reduction in the number of juveniles was observed, and at AZO concentration of 50 mga.i./kgD.W and higher, F1 did not reproduce. Significant oxidative stress was observed in all generations, with increased SOD and lipid damage that slowly decreased in subsequent generations. Transgenerational effects were also observed, with a significantly reduced number of juveniles in F1 and significant oxidative stress and lipid damage in all generations. IBRv2 showed that F1 was most affected, followed by F0, and least affected was F3. When considering the whole body energy budget, F1 to F3 had significantly higher WBEB compared to F0, and a shift in proportion of energy reserves occurred in F1, where the proportion of lipids increased while protein decreased. Results of this research show that considering standard toxicity tests, risks for populations of soil organisms are possibly severely underestimated. Therefore, standard toxicity guidelines should be supplemented by multigenerational tests, when possible.

Cadmium induced time-dependent kidney injury in common carp via mitochondrial pathway: Impaired mitochondrial energy metabolism and mitochondrion-dependent apoptosis

Toxic effect of heavy metal cadmium (Cd) on fish kidneys had been reported. Mitochondrion is an important organelle for maintaining kidney function, while its role in Cd-induced kidney injury in common carp remained unclarified. In this experiment, we established a poisoning model of common carp with Cd exposure (0.26 mg/L) for 15, 30, and 45 days. Serum biochemistry determination, histological observation, TUNEL assay, qRT-PCR, Western blot, and integrated biomarker response (IBR) were applied to assess the nephrotoxicity of Cd to common carp. Our results displayed that Cd exposure increased the levels of serum biochemical indexes (UREA, CRE, and UA), indicating kidney injury. We further revealed via histological observation that Cd damaged structural integrity of kidneys, as evidenced by renal glomerulus and renal tubular injury, hallmark phenotypes of apoptosis, and mitochondrial damage, suggesting that mitochondria damage and apoptosis were involved in Cd-induced kidney injury. Moreover, Cd exposure decreased ATPase (Na⁺/K⁺-ATPase, Ca²⁺-ATPase, Mg²⁺-ATPase, and Ca²⁺Mg²⁺-ATPase) activities as well as PGC-1a and Mfn2 levels, while increased Drp1 and PINK1 levels as well as LC3-II/LC3-I ratio, which indicated that Cd-impaired renal energy metabolism was related to mitochondrial dysfunction. Additionally, we found that Cd induced oxidative stress (abnormal levels of SOD, CAT, GPX, MDA, and H₂O₂) in kidneys, which was involved in triggering mitochondrial dysfunction and further impairing mitochondrial energy metabolism. Moreover, the occurrence of mitochondria-dependent apoptosis was found after Cd-exposure in common carp kidneys, as indicated by enhanced levels of Bax, CytC, APAF1, Caspase-9, and Caspase-3, while declined level of Bcl-2. Subsequently, we confirmed a time-dependent nephrotoxicity of Cd to common carp via IBR assessment. In conclusion, Cd induced time-dependent nephrotoxicity in common carp via mitochondrial pathway. This mitochondria-oriented study shed light on underlying mechanisms of Cd-induced renal pathologies and provided a theoretical basis for evaluating Cd toxicity to aquatic organisms.

Short-term effects of the strobilurin fungicide dimoxystrobin on zebrafish gills: A morpho-functional study

Strobilurins represent the most widely used class of fungicides nowadays andare considered relatively non-toxic to mammals and birds but highly toxic to aquatic biota. Dimoxystrobin is one of the novel strobilurins, recently included in the 3rd Watch List of the European Commission as available data indicate that it could pose a significant risk to aquatic species. As yet, the number of studies explicitly assessing the impact of this fungicide on terrestrial and aquatic species is extremely low, and the toxic effects of dimoxystrobin on fish have not been reported. Here we investigate for the first time the alterations induced by two environmentally relevant and very low concentrations of dimoxystrobin (6.56 and 13.13 μg/L) in the fish gills. morphological, morphometric, ultrastructural, and functional alterations have been evaluated using zebrafish as a model species. We demonstrated that even short-term exposure (96 h) to dimoxystrobin alters fish gills reducing the surface available for gas exchange and inducing severe alterations encompassing three reaction patterns: circulatory disturbance and both regressive and progressive changes. Furthermore, we revealed that this fungicide impairs the expression of key enzymes involved in osmotic and acid-base regulation (Na⁺/K⁺-ATPase and AQP3) and the defensive response against oxidative stress (SOD and CAT). The information presented here highlights the importance of combining data from different analytical methods for evaluating the toxic potential of currently used and new agrochemical compounds. Our results will also contribute to the discussion on the suitability of mandatory ecotoxicological tests on vertebrates before the introduction on the market of new compounds.

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.

Assessment of the effect of sub-lethal acute toxicity of Emamectin benzoate in Labeo rohita using multiple biomarker approach

Emamectin benzoate (EMB) is a potent neurotoxin agent, widely used for ectoparasites control in aquaculture, but their detailed toxicological implications in Labeo rohita are unknown. Thus, this study was conceptualized to determine the LC₅₀ and to investigate the effects of two sub-lethal concentrations 1/50th of 96 h LC₅₀ (1.82 μgL^-1) and 1/10thof 96 h LC₅₀ (9.1 μgL^-1) on hemato-immunological and biochemical responses in L. rohita (mean weight 25.54 ± 2.3 g and length 10.35 ± 2.4 cm) for a period of 24 h, 48 h, and 72 h. LC₅₀ of EMB were 163 μgL^-1, 112 μgL^-1, 99 μgL^-1 and 91 μgL^-1 at 24 h, 48 h, 72 h, and 96 h respectively. The safe limit at 96 h LC₅₀ of EMB was 2.30 μgL^-1. In EMB treated fish, red blood cells, white blood cells, hemoglobin, and hematocrit counts were reduced (p < 0.05) significantly. Superoxide dismutase (SOD) activity in the liver and kidney declined (p < 0.05) at 72 h while in gill and muscle the activity increased significantly. Glutathione-s-transferase (GST) activity in the liver, gill, and kidney increased (p < 0.05) while muscle decreased significantly. Catalase (CAT) activity in liver, gill, and muscle decreased while in kidney increases. Glutamic-oxaloacetic acid transaminase (GOT) activity and Glutamate pyruvate transaminase (GPT) activity were increased in liver, kidney, and muscle tissue. The change in serum triglycerides, serum protein level was noticed. The level of cortisol, heat shock protein 70 (HSP70), and HSP90 increased (p < 0.05) while the immunological responses like immunoglobulin M (IgM) and complement 3(C3) activity decreased (p < 0.05) in EMB exposed fish. Thus, EMB exposure at two sub-lethal concentrations in L. rohita induces several hemato-immuno, and biochemical alterations in blood, serum, and different organs. The overall result of the present study indicated that EMB is toxic to fish even for a short-term exposure and low doses, and therefore utmost caution should be taken to prevent their drainage into water bodies.

Evaluating Multiple Biochemical Markers in Xenopus laevis Tadpoles Exposed to the Pesticides Thiacloprid and Trifloxystrobin in Single and Mixed Forms

Pesticide exposure is thought to be one of the common reasons for the decline in amphibian populations, a phenomenon that is a major threat to global biodiversity. Although the single effects of pesticides on amphibians have been well studied, the effects of mixtures are not well known. The present study aimed to evaluate the acute toxicity of the insecticide thiacloprid and the fungicide trifloxystrobin on early developmental stages of Xenopus laevis using various biochemical markers (glutathione S-transferase, glutathione reductase, acetylcholinesterase, carboxylesterase, glutathione peroxidase, catalase, alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, Na⁺ K⁺ -adenosine triphosphatase [ATPase], Ca²⁺ -ATPase, Mg²⁺ -ATPase, and total ATPase). The median lethal concentrations (LC50s) of thiacloprid and trifloxystrobin were determined to be 3.41 and 0.09 mg a.i. L^-1 , respectively. Tadpoles were exposed to the LC50, LC50/2, LC50/10, LC50/20, LC50/50, and LC50/100 of these pesticides. Both pesticides significantly affected (inhibited/activated) the biomarkers even at low concentrations. The pesticides showed a synergistic effect when applied as a mixture and altered the biomarkers more than when applied individually. In conclusion, we can assume that tadpoles are threatened by these pesticides even at environmentally relevant concentrations. Our findings provide important data to guide management of the ecotoxicological effects of these pesticides on nontarget amphibians.  Environ Toxicol Chem 2021;40:2846-2860. © 2021 SETAC.

The effect of chronic exposure to chloridazon and its degradation product chloridazon-desphenyl on signal crayfish Pacifastacus leniusculus

The effects of chloridazon (Ch) and its metabolite chloridazon-desphenyl (Ch-D) at the environmentally relevant concentrations of 0.45 µg/L and 2.7 µg/L on signal crayfish Pacifastacus leniusculus were assessed in a 30-day exposure followed by a 15-day depuration period. Locomotion, biochemical haemolymph profile, oxidative and antioxidant parameters, and histopathology were evaluated. Crayfish exposed to Ch at 0.45 µg/L and 2.7 µg/L showed significantly (p < 0.01) higher CAT activity and GSH level in hepatopancreas and gill compared to controls. The concentration of Ch at 2.7 µg/L was associated with significantly (p < 0.01) higher levels of GLU, LACT, ALT, AST in haemolymph compared to controls. Chloridazon-desphenyl exposure at both tested concentrations caused significantly higher (p < 0.01) GLU, LACT, ALT, AST, NH₃, and Ca in haemolymph; lipid peroxidation (TBARS) levels in hepatopancreas; and CAT activity and GSH level in hepatopancreas and gill. Alterations of structure including focal dilatation of tubules, increased number of fibrillar cells, and haemocyte infiltration in the interstitium were observed with 2.7 µg/L Ch and with both Ch-D exposures. Locomotion patterns did not vary significantly among groups. A 15-day recovery period was insufficient to restore normal physiological parameters in exposed groups. Chloridazon and its metabolite Ch-D exerts harmful effects on crayfish.