Antioxidant responses of Annelids, Brassicaceae and Fabaceae to pollutants: a review

Adverse effects of environmentally relevant microplastics on in vivo endpoints, oxidative stress, and mitogen-activated protein kinase signaling pathway and multixenobiotic resistance system in the marine rotifer Brachionus plicatilis

This study compared the toxicological effects of environmentally relevant microplastics (MPs) on the marine rotifer Brachionus plicatilis, focusing on MPs derived from various sources, including fossil fuel-based low-density polyethylene, bio-based polylactic acid (PLA), biodegradable poly(butylene adipate-co-terephthalate), and a novel PLA modified with β-cyclodextrin. We assessed in vivo effects such as reproductive output and mortality, alongside in vitro oxidative stress responses, including oxidative stress, antioxidant enzyme activities, and activation of the mitogen-activated protein kinase (MAPK) signaling pathway and the multixenobiotic resistance (MXR) system. Reproductive output and lifespan reduced significantly across all MP types, ranging from 0.5 to 10 mg L-1, indicating compromised reproductive fitness and life maintenance. At an environmentally relevant concentration of 0.5 mg L-1, in vitro assessments revealed differential modulation of reactive oxygen species levels and antioxidant enzyme activities, contingent upon the specific MP type. Moreover, MAPK signaling pathway and MXR assays showed changes in phosphorylation and detoxification proteins depending on the type of MPs. This study highlights the ecological risks that various MPs, including bio-based, biodegradable, and petrochemical-based MPs, could pose in marine environments.

Antioxidant-related enzymes and peptides as biomarkers of metallic nanoparticles (eco)toxicity in the aquatic environment

Increased awareness of the impact of human activities on the environment has emerged in recent decades. One significant global environmental and human health issue is the development of materials that could potentially have negative effects. These materials can accumulate in the environment, infiltrate organisms, and move up the food chain, causing toxic effects at various levels. Therefore, it is crucial to assess materials comprising nano-scale particles due to the rapid expansion of nanotechnology. The aquatic environment, particularly vulnerable to waste pollution, demands attention. This review provides an overview of the behavior and fate of metallic nanoparticles (NPs) in the aquatic environment. It focuses on recent studies investigating the toxicity of different metallic NPs on aquatic organisms, with a specific emphasis on thiol-biomarkers of oxidative stress such as glutathione, thiol- and related-enzymes, and metallothionein. Additionally, the selection of suitable measurement methods for monitoring thiol-biomarkers in NPs' ecotoxicity assessments is discussed. The review also describes the analytical techniques employed for determining levels of oxidative stress biomarkers.

Joint toxic mechanism of clothianidin and prochloraz in the earthworm (Eisenia fetida)

Pesticides are typically present as combinations within soil ecosystems and have detrimental effects on untamed surroundings. However, the collective impacts and fundamental mechanisms of pesticides on soil living beings are currently inadequately assessed. In our current work, we evaluated the interactive consequences of clothianidin (CLO) and prochloraz (PRO) on earthworms (Eisenia fetida) using several toxicological tests, such as acute adverse effects, biocatalytic activity, and alterations in transcriptional activity. The findings revealed that CLO (with a 14-day LC50 value of 6.08 mg kg-1) exhibited greater toxicity compared to PRO (with a 14-day LC50 value of 79.41 mg kg-1). Moreover, the combinations of CLO and PRO had synergistic acute effects on E. fetida. Additionally, the activities of POD, CAT, and GST were significantly varied in most instances of single and mixed treatments when compared to the control. Surprisingly, the transcriptional levels of four genes (gst, sod, crt, and ann), related to oxidative load, metabolic detoxification systems, endoplasmic reticulum, and oxytocin neuropeptide, respectively, were also altered in response to single and mixture exposures, as compared to the control. Alterations in enzyme activity and gene transcriptional level could serve as early indicators for detecting co-exposure to pesticides. The findings of this research offered valuable holistic understanding regarding the toxicity of pesticide combinations on earthworms. Further research should be conducted to investigate the persistent effects of pesticide mixtures on terrestrial invertebrates in order to draw definitive conclusions about the associated risks.

Mixture toxicity study of two metal oxide nanoparticles and chlorpyrifos on Eisenia andrei earthworms

Co-exposure soil studies of pollutants are necessary for an appropriate ecological risk assessment. Here, we examined the effects of two-component mixtures of metal oxide nanoparticles (ZnO NPs or goethite NPs) with the insecticide chlorpyrifos (CPF) under laboratory conditions in short-term artificial soil assays using Eisenia andrei earthworms. We characterized NPs and their mixtures by scanning electron microscopy, atomic force microscopy, dynamic light scattering and zeta potential, and evaluated effects on metal accumulation, oxidative stress enzymes, and neurotoxicity related biomarkers in single and combined toxicity assays. Exposure to ZnO NPs increased Zn levels compared to control in single and combined exposure (ZnO NPs + CPF) at 72 h and 7 days, respectively. In contrast, there was no indication of Fe increase in organisms exposed to goethite NPs. One of the most notable effects on oxidative stress biomarkers was produced by single exposure to goethite NPs, showing that the worms were more sensitive to goethite NPs than to ZnO NPs. Acetylcholinesterase and carboxylesterase activities indicated that ZnO NPs alone were not neurotoxic to earthworms, but similar degrees of inhibition were observed after single CPF and ZnO NPs + CPF exposure. Differences between single and combined exposure were found for catalase and superoxide dismutase (goethite NPs) and for glutathione S-transferase (ZnO NPs) activities, mostly at 72 h. These findings suggest a necessity to evaluate mixtures of NPs with co-existing contaminants in soil, and that the nature of metal oxide NPs and exposure time are relevant factors to be considered when assessing combined toxicity, as it may have an impact on ecotoxicological risk assessment.

A multi-biomarker approach to verify chronic effects on Eisenia andrei earthworms exposed to tailings from one of the world's largest mining disasters

Mining is of great relevance to the global economy, but its activities are challenging due to socio-environmental impacts. In January 2019, an iron ore tailings dam collapsed in Brumadinho (Minas Gerais, Brazil) releasing 12 × 106 m3 of tailings, causing human losses and devastation around 3.13 × 106 m2 of a watershed. In this context, the present study aimed to investigate the potential toxic effects of tailings from the collapsed dam using earthworms Eisenia andrei as a model organism for terrestrial environments. An extensive set of tests was performed, including behavioral (avoidance), acute (mortality and biomass) and chronic tests, such as biomass, reproduction and cytotoxicity (viability and cell density and change in coelomocyte pattern). The physical-chemical characterization revealed a higher density of the tailings in relation to the control soil, which can result in physical changes, such as soil compaction and surface sealing. Aluminum, Ca, Fe, Hg, Mg, Mn, K, Na and P registered higher concentrations in the tailings compared to the control soil, while Total Nitrogen, Total Organic Carbon and Organic Matter were higher in the natural soil. Based on the avoidance test, an EC50 of 27.18 ± 2.83% was estimated. No lethality was observed in the acute exposure, nor variations in biomass in the acute and chronic assays. However, there was a tendency to reduce the number of juveniles in relation to cocoons in the proportions of 3125; 12.5 and 25%. Significant changes in viability, cell density and pattern of amebocytes and eleocytes were observed up to the 35th day of exposure. A multi-biomarker approach (Integrated Biological Response version 2) indicated concentration-dependent effects and attenuation of cellular changes over time. These are the first results of chronic effects on earthworms exposed to tailings from the B1 dam. Despite being conclusive, we highlight the possible heterogeneity of the tailings and the necessary care in extrapolating the results.

Can antimony contamination in soil undermine the ecological contributions of earthworms?

As antimony (Sb) has been increasingly used in manufacturing industries (e.g., alloy, polymer and electronics industries), Sb contamination in the soil environment becomes widely reported and has drawn growing attention due to the toxicity of Sb to living organisms. Whether soil-dwelling organisms can tolerate Sb toxicity and maintain their ecological functions remains poorly understood. Using a cosmopolitan, ecologically important earthworm species (Eisenia fetida) as an ideal model organism, we examine the effects of Sb on the physiological, molecular and behavioural responses of earthworms to different levels of Sb contamination in soil (0, 10, 50, 100, 250 and 500 mg/kg). We found that earthworms could tolerate heavy Sb contamination (100 mg/kg) by boosting their antioxidant defence (POD and GST) and immune systems (ACP) so that their body weight and survival rate were sustained (c.f. control). However, these systems were compromised under extreme Sb contamination (500 mg/kg), leading to mortality. As such, earthworms exhibited avoidance behaviour to escape from the Sb-contaminated soil, implying the loss of their ecological contributions to the environment (e.g., increase in soil aeration and maintenance of soil structure). By measuring various types of biomarkers along a concentration gradient, this study provides a mechanistic understanding of how earthworms resist or succumb to Sb toxicity. Since extreme Sb contamination in soil (>100 mg/kg) is rarely found in nature, we are optimistic that the health and performance of earthworms are not influenced by Sb in most circumstances, but regular monitoring of Sb in soil is recommended to ensure the integrity and functioning of soil environment. Further studies are recommended to evaluate the long-term impact of Sb in the soil ecosystem through bioaccumulation and trophic transfer among soil-dwelling organisms.

Evaluation of Acute Toxicity and Antioxidant Response of Earthworm Exposed to a Lignin-Modified Crosslinked Hydrogel

Hydrogels are polymers of great importance due to their multiple applications, which have led to an exponential increase in their production. However, once they have fulfilled their function, they become waste and their ecotoxicological effects are unknown. The aim of the present study was to evaluate the acute toxicity and total antioxidant capacity of the earthworm (Eisenia fetida) exposed to a terpolymeric hydrogel (acrylic acid, acrylamide, and 2-acrylamido-2-methyl-1-propane-sulfonic acid) crosslinked with modified kraft lignin. Four different amounts of hydrogel per unit area were evaluated (0.0924, 0.1848, 0.9242, and 1.848 mg hydrogel/cm²) plus a control, and three replicates were performed for each group. Starting from the amount of 0.1848 mg hydrogel/cm², the earthworms showed physiological and behavioral alterations; at higher amounts, 0.9242 and 1.848 mg hydrogel/cm², more acute signs were observed with mortality rates of 51.7% and 100%, respectively. On the other hand, the antioxidant activity assay showed that the higher the hydrogel exposure amount, the higher the oxidative stress, as evidenced by lower antioxidant activity (67.09% inhibition of the ABTS^●+ radical). Therefore, we concluded that the lignin-modified hydrogel generated oxidative stress and acute lethal toxic effects in Eisenia fetida.

Oxidative stress and gene expression induced by biodegradable microplastics and imidacloprid in earthworms (Eisenia fetida) at environmentally relevant concentrations

The environmental issues caused by biodegradable microplastics (BMPs) from polylactic acid (PLA) as well as pesticides are of increasing concern nowadays. In this study, the toxicological effects of the single and combined exposure of PLA BMPs and imidacloprid (IMI), a neonicotinoid insecticide, on earthworms (Eisenia fetida) were investigated in terms of oxidative stress, DNA damage, and gene expression, respectively. The results showed that compared with the control, SOD, CAT and AChE activities in the single and combined treatments decreased significantly, and POD activity showed an "inhibition-activation" trend. SOD and CAT activities of combined treatments on day 28 and AChE activity of combined treatment on day 21 were significantly higher than those of the single treatments. For the rest of the exposure period, SOD, CAT and AChE activities in the combined treatments were lower than those in the single treatments. POD activity in the combined treatment was significantly lower than those of single treatments at day 7 and higher than that of single treatments at day 28. MDA content showed an "inhibition-activation-inhibition" trend, and the ROS level and 8-OHdG content increased significantly in both the single and combined treatments. This shows that both single and combined treatments led to oxidative stress and DNA damage. ANN and HSP70 were expressed abnormally, while the SOD and CAT mRNA expression changes were generally consistent with the corresponding enzyme activities. The integrated biomarker response (IBR) values were higher under combined exposures than single exposures at both biochemical and molecular levels, indicating that combined treatment exacerbated the toxicity. However, the IBR value of the combined treatment decreased consistently at the time axis. Overall, our results suggest that PLA BMPs and IMI induce oxidative stress and gene expression in earthworms at environmentally relevant concentrations, thereby increasing the risk of earthworms.

Phycotoxins and marine annelids - A global review

Several species of microalgae can produce potent phycotoxins that negatively affect aquatic organisms and their consumers following different exposure routes, as well as toxicokinetic (TK) and toxicodynamic (TD) processes. Benthic organisms are especially vulnerable as they are exposed to both benthic and planktonic species causative of harmful algal blooms (HABs). While benthic algae can come into direct contact with annelids during substrate remobilization, planktonic cells can settle to the bottom mostly during senescence and/or encystment stages, and in shallow and calm waters. We performed a systematic, qualitative review of the literature on the phycotoxin TK and TD processes in marine annelids, summarizing the most relevant findings and general trends. Besides, by using innovative analytical/statistical approaches, we were able to detect patterns and gaps in the current literature, thus pointing to future research directions. We retrieved and analyzed studies involving diarrhetic shellfish toxins (DSTs), paralytic shellfish toxins (PSTs), brevetoxins (PbTXs), domoic acid (DA), as well as palytoxin and its congeners, the ovatoxins (treated together as PLTXs). It is worth mentioning that studies evaluating other phycotoxins (e.g., ciguatoxins, yessotoxins) were not found in the literature. The absence of data on PbTXs, PSTs and DA is the largest gap hampering TK assessment in annelids, although some relevant information on TD is already available. Whereas lethal effects from DSTs have not been reported, more potent toxins like PbTXs, PSTs, DA and those grouped as PLTX-like compounds can cause mortality and/or marked decrease in annelid abundance. In addition, phycotoxins have been linked to sublethal effects on annelid cells. Although very sparse, field and laboratory studies offer strong evidence that annelids may be reliable indicators of toxin exposure and their negative effects during both early and later stages of HABs in marine environments. Besides quickly responding to these compounds at both organismic and suborganismic levels, annelids are easily found in areas affected by HABs. The use of annelids in future investigations evaluating the action mechanisms of toxic microalgae on marine invertebrates should be thus encouraged. In this case, the choice for widely dispersed and numerically dominant species of annelids would strengthen the validation and extrapolation of results from risk assessments in areas affected by HABs worldwide.

Heat stress delays detoxification of phenanthrene in the springtail Folsomia candida

Climate change has intensified the occurrence of heat waves, resulting in organisms being exposed to thermal and chemical stress at the same time. The effects of mild heat shock combined with sublethal concentrations of phenanthrene (PHE) on defense mechanisms in springtails Folsomia candida were investigated. The transcription of Heat Shock Protein 70 (HSP70) was significantly upregulated by heat shock but tended to reach the control levels after 42 h of recovery. The transcription of cytochrome P450 3A13 (CYP3A13) was upregulated 3-13 fold by PHE but suppressed by heat shock. The suppression by heat shock might contribute to the reduced detoxification of PHE during high-temperature exposure. In line with this, we found that the internal PHE concentration was approximately 70% higher in heat-shocked springtails than in animals kept at control temperature. In general, the transcription of genes encoding enzymes of detoxification phase Ⅱ (glutathione S-transferase 3) and phase Ⅲ (ABC transporter 1) and the activity of antioxidant defense enzymes (superoxide dismutase and catalase) were less influenced than genes encoding phase I detoxification mechanisms (CYP3A13). These results indicate that heat shock delays the detoxification of PHE in springtails.

Ecotoxicological responses of Daphnia magna and Eisenia andrei in landfill leachate

Leachate toxicity using bioindicators such as microcrustaceans and earthworms has not been fully elucidated. These bioindicators are traditionally determined through physicochemical and microbiological analyses. The ecotoxicological assessment of leachate using indicator organisms from different environments is a technique to ensure the treatment and safe disposal of this effluent with minimum impact on human health and the environment. The current study aimed to evaluate the ecotoxicological responses of Daphnia magna and Eisenia andrei in landfill leachate, identifying which organism was more sensitive to this effluent. The leachate used in ecotoxicological tests was collected at the Campina Grande Sanitary Landfill (ASCG), Paraíba, Brazil. The leachate sample contained a high content of organic matter in the form of chemical oxygen demand (19496.86 mg.L^-1) and ammoniacal nitrogen (2198.00 mg.NL^-1), in addition to metals with carcinogenic potential, such as Cr (0.64 mg.L^-1) and Fe (1.16 mg.L^-1). The exposure of Daphnia magna to the leachate showed that the effluent is harmful to aquatic organisms, obtaining an EC 50, 48 h = 1.22%, FT of 128 and a TU of 81.96%. Among the contaminant concentrations tested in Eisenia andrei, 57% (59.28 mL.kg^-1) caused the highest lethality, causing the death of 21 earthworms within 72 hours of exposure. The avoidance test showed that exposure to leachate concentrations between 10.38 and 39.86 mL.kg^-1 led to the leakage of earthworms, and habitat loss was observed at a concentration of 55.80 mL.kg^-1, in which leak response (LR) ≥80% was obtained. This study demonstrates that the mentioned organisms are suitable for ecotoxicological tests in landfill leachate. Moreover, the microcrustacean Daphnia magna showed the most significant sensitivity, presenting a rapid ecotoxicological response to the leachate.

Single and Mixture Toxicity of Boron and Vanadium Nanoparticles in the Soil Annelid Enchytraeus crypticus: A Multi-Biomarker Approach

The increased use and production of new materials has contributed to Anthropocene biodiversity decrease. Therefore, a careful and effective toxicity evaluation of these new materials is crucial. However, environmental risk assessment is facing new challenges due to the specific characteristics of nanomaterials (NMs). Most of the available ecotoxicity studies target the aquatic ecosystems and single exposures of NMs. The present study evaluated Enchytraeus crypticus survival and reproduction (28 days) and biochemical responses (14 days) when exposed to nanoparticles of vanadium (VNPs) and boron (BNPs) (single and mixture; tested concentrations: 10 and 50 mg/kg). Although at the organism level the combined exposures (VNPs + BNPs) did not induce a different toxicity from the single exposures, the biochemical analysis revealed a more complex picture. VNPs presented a higher toxicity than BNPs. VNPs (50 mg/kg), independently of the presence of BNPs (additive or independent effects), caused a decrease in survival and reproduction. However, acetylcholinesterase, glutathione S-transferase, catalase, glutathione reductase activities, and lipid peroxidation levels revealed alterations in neurotoxicity, detoxification and antioxidant responses, depending on the time and type of exposure (single or mixture). The results from this study highlight different responses of the organisms to contaminants in single versus mixture exposures, mainly at the biochemical level.

Similarities and differences among the responses to three chlorinated organophosphate esters in earthworm: Evidences from biomarkers, transcriptomics and metabolomics

The wide use of chlorinated organophosphate esters (Cl-OPEs) as additive flame retardants has aroused concern about their potential risks on ecosystem and human health. However, knowledge about the toxicity of Cl-OPEs on soil organisms remains limited. In this study, earthworms, Eisenia fetida, were exposed to three representative Cl-OPEs, i.e., tris(2-chloroethyl) phosphate (TCEP), tris(2-chloro-1-methylethyl) phosphate (TCPP), and tris(1,3-dichloro-2-propyl) phosphate (TDCPP) in artificial soil. Using a combination of biochemical indicators (biomarkers), transcriptomics, and metabolomics, we compared the Cl-OPE-induced toxicity to E. fetida and provide new insight into the related molecular mechanism. All three Cl-OPEs elicited immune defense by the earthworms, as evidenced by increased acid phosphatase and alkaline phosphatase activities, and the genes involved in immune-related pathways (e.g., lysosomal and interleukin-17 signaling pathways). Furthermore, no effects on acetylcholinesterase activity were observed among the three Cl-OPEs. However, the TCPP and TDCPP treatments significantly decreased the neurotransmitter serotonin, suggesting the potential neurotoxicity of Cl-OPEs. Although TCEP affected the genes involved in carbohydrate and amino acid metabolism, the changes in the corresponding metabolites were not statistically significant. In contrast, exposure to TCPP and TDCPP induced oxidative stress, and affected xenobiotic metabolism and energy metabolism, leading to the decreased body weight in E. fetida. Based on these toxic effects, TCPP and TDCPP were more severely toxic than TCEP, despite their structural similarity. Given that the use of TCEP has been tightly regulated, our results suggest the potentially toxic effects of TCPP and TDCPP should not be ignored in future risk assessments of flame retardants.

In vitro cultivation of primary intestinal cells from Eisenia fetida as basis for ecotoxicological studies

The earthworm Eisenia fetida is a commonly used model organism for unspecific soil feeders in ecotoxicological studies. Its intestinal cells are the first to encounter possible pollutants co-ingested by the earthworm, which makes them prime candidates for studies of toxic effects of environmental pollutants on the cellular as compared to the organismic level. In this context, the aim of this study was to demonstrate the suitability of preparations of primary intestinal E. fetida cells for in vitro ecotoxicological studies. For this purpose, a suitable isolation and cultivation protocol was established. Cells were isolated directly from the intestine, maintaining >85% viability during subsequent cultivations (up to 144 h). Exposure to established pollutants and soil elutriates comprising silver nanoparticles and metal ions (Cu²⁺, Cd²⁺) induced a significant decrease in the metabolic activity of the cells. In case of microplastic particles (MP particles), namely 0.2, 0.5, 2.0, and 3.0 µm diameter polystyrene (PS) beads as well as 0.5 and 2.0 µm diameter polylactic acid (PLA) beads, no active uptake was observed. Slight positive as well as negative dose and size dependent effects on the metabolism were seen, which to some extent might correlate with effects on the organismic level.

Bioaccumulation, elimination and metabolism in earthworms and microbial indices responses after exposure to decabromodiphenyl ethane in a soil-earthworm-microbe system

As a novel brominated flame retardant (NBFR), decabromodiphenyl ethane (DBDPE) has been poorly understood for the environmental fate and toxicity in terrestrial invertebrates. For the first time, the bioaccumulation, elimination, metabolism and detoxification of DBDPE in earthworms as well as its potential impacts on soil microbes were investigated. The results showed much higher DBDPE concentrations in casts than in earthworms. The bioaccumulation factor (BAF) and elimination rate constant (k_e) values were 0.028-0.213 (gdw, worm/gdw, soil) and 0.323-0.452 (day^-1), respectively. The detoxifying enzymes (CYP450 and GST) could be induced by DBDPE within the range of exposure dosage, and the activities were significantly increased at 21 d (p < 0.05). The results were identified by GC-ECNI-MS, and it showed that at least eleven unknown peaks were separately observed in the earthworms, which were the biotransformation products of DBDPE in earthworms. Additionally, the damages, including skin shrinkage, setae impairment, and intercellular vacuolization, were clearly observed by SEM/TEM. Based on these data, DBDPE could accumulate in earthworms, yet, with low bioaccumulation ability. Moreover, DBDPE exposure resulted in minimal harmful impacts on microbial activities including microbial biomass C (MBC), Microbial basal respiration (MBR), Urease (US) activity and fluorescein diacetate hydrolase (FDA) activity (p < 0.05). Our findings would provide some essential information for interpreting the ecological risks of DBDPE in soil.

Ecotoxicological responses of Eisenia andrei exposed in field-contaminated soils by sanitary sewage

The disposal of untreated sanitary sewage in the soil has several consequences for human health and leads to environmental risks; thus, it is necessary investigating, monitoring and remediating the affected sites. The aims of the current study are to evaluate ecotoxicological effects on Eisenia andrei earthworms exposed to soil subjected to sources of sanitary sewage discharge and to investigate whether prevention values established by the Brazilian legislation for soil quality, associated with the incidence of chemical substances in it, are satisfactory enough to assure the necessary quality for different organisms. Earthworms' behavior, reproduction, acetylcholinesterase activity, catalase, superoxide dismutase and malondialdehyde levels were evaluated. The reproduction and behavior of earthworms exposed to sanitary sewage were adversely affected. Increased superoxide dismutase and catalase activity acted as antioxidant defense mechanism. Significantly increased lipid peroxidation levels and acetylcholinesterase activity inhibition have indicated lipid peroxidation in cell membrane and neurotransmission changes, respectively. Results have confirmed that sanitary sewage induced oxidative stress in earthworms. In addition, based on biochemical data analysis, the integrated biomarker response (IBR) has evidenced different toxicity levels in earthworms between the investigated points. Finally, results have indicated that effluents released into the soil, without proper treatment, lead to contaminant accumulation due to soil saturation and it can hinder different processes and biological development taking place in the soil. In addition, the current study has shown that physical-chemical analyses alone are not enough to assess soil quality, since it is also requires adopting an ecotoxicological approach. Brazilian legislation focused on soil quality must be revised and new guiding values must be proposed.

Arginase Activity in Eisenia andrei Coelomocytes: Function in the Earthworm Innate Response

Arginase is the manganese metalloenzyme catalyzing the conversion of l-arginine to l-ornithine and urea. In vertebrates, arginase is involved in the immune response, tissue regeneration, and wound healing and is an important marker of alternative anti-inflammatory polarization of macrophages. In invertebrates, data concerning the role of arginase in these processes are very limited. Therefore, in the present study, we focused on the changes in arginase activity in the coelomocytes of Eisenia andrei. We studied the effects of lipopolysaccharide (LPS), hydrogen peroxide (H₂O₂), heavy metals ions (e.g., Mn²⁺), parasite infection, wound healing, and short-term fasting (5 days) on arginase activity. For the first time in earthworms, we described arginase activity in the coelomocytes and found that it can be up-regulated upon in vitro stimulation with LPS and H₂O₂ and in the presence of Mn²⁺ ions. Moreover, arginase activity was also up-regulated in animals in vivo infected with nematodes or experiencing segment amputation, but not in fasting earthworms. Furthermore, we confirmed that the activity of coelomocyte arginase can be suppressed by l-norvaline. Our studies strongly suggest that similarly to the vertebrates, also in the earthworms, coelomocyte arginase is an important element of the immune response and wound healing processes.

Molybdenum Supply Alleviates the Cadmium Toxicity in Fragrant Rice by Modulating Oxidative Stress and Antioxidant Gene Expression

Increasing evidence shows that cadmium (Cd) toxicity causes severe perturbations on growth performance, physio-biochemical and molecular processes in crop plants. Molybdenum (Mo), an essential trace element, plays key roles in oxidative stress tolerance of higher plants. Hence, the present study has been conducted to investigate the possible role of Mo in alleviating Cd-induced inhibitions in two fragrant rice cultivars namely Guixiangzhan (GXZ) and Meixiangzhan-2 (MXZ-2). The results revealed that Mo application enhanced the plant dry biomass by 73.24% in GXZ and 58.09% in MXZ-2 under Cd stress conditions, suggesting that Mo supplementation alleviated Cd-induced toxicity effects in fragrant rice. The enhanced Cd-tolerance in fragrant rice plants prompted by Mo application could be ascribed to its ability to regulate Cd uptake and reduce Cd-induced oxidative stress as evident by lower hydrogen peroxide levels, electrolyte leakage and malondialdehyde contents in Cd-stressed plants. The ameliorative role of Mo against Cd-toxicity also reflected through its protection to the photosynthetic pigments, proline and soluble protein. Mo also induced antioxidant defense systems via maintaining higher contents of glutathione and ascorbate as well as enhancing the ROS-detoxifying enzymes such as catalase, peroxidase, superoxide dismutase and ascorbate peroxidase activities and up-regulating transcript abundance in both fragrant rice cultivars under Cd stress. Conclusively, Mo-mediated modulation of Cd toxicity in fragrant rice was through restricting Cd uptake, maintaining photosynthetic performance and alleviating oxidative damages via the strong anti-oxidative defense systems; however, GXZ cultivar is comparatively more Cd tolerant and Mo-efficient as evident from the less growth inhibition and biomass reduction as well as enhanced Mo-induced Cd stress tolerance and less oxidative damage than MXZ-2 fragrant rice cultivar.

Embryonic development and oxidative stress effects in the larvae and adult fish livers of zebrafish (Danio rerio) exposed to the strobilurin fungicides, kresoxim-methyl and pyraclostrobin

Two important strobilurin fungicides, kresoxim-methyl and pyraclostrobin, are widely used globally. Their effects on embryonic development and oxidative stress effects in the larvae and adult fish livers of zebrafish (Danio rerio) were assessed in our study. The hatching, mortality, and teratogenic rates were determined when the eggs of fish were exposed to kresoxim-methyl and pyraclostrobin for 24-144 h postfertilization (hpf). For further study, the effects of kresoxim-methyl and pyraclostrobin on antioxidant enzymes [catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD)], detoxification enzymes [carboxylesterase (CarE) and glutathione S-transferase (GST)] and the malondialdehyde (MDA) content of larval zebrafish (96 h) and male or female adult zebrafish livers (up to 28 d) were evaluated for potential toxicity mechanisms. The study of embryonic development revealed that both kresoxim-methyl and pyraclostrobin caused developmental toxicity (hatching inhibition, mortality, and teratogenic rates) increase with significant concentration- and time-dependent responses, and the 144-h median lethal values (LC₅₀) of kresoxim-methyl and pyraclostrobin were 195.0 and 81.3 μg L^-1, respectively. In the larval zebrafish study, both kresoxim-methyl and pyraclostrobin at the highest concentrations (100 μg L^-1 and 15 μg L^-1, respectively) significantly increased the CAT, POD and CarE activities and MDA content compared with those of the control group (P < 0.05). We further found that oxidative stress effects in adult zebrafish livers caused by long-term kresoxim-methyl and pyraclostrobin exposure differed with time and sex. Regarding the residues in natural waters, the potential adverse effects of kresoxim-methyl and pyraclostrobin would be relatively low for adult zebrafish but must not be overlooked for zebrafish embryos/larvae (hatching impairment). Our results from the detoxification enzyme study also initially indicated that adult zebrafish had a greater detoxification ability than larvae and that males had a greater detoxification ability than females.

The vital function of humic acid with different molecular weight in controlling Cd and Pb bioavailability and toxicity to earthworm (Eisenia fetida) in soil

Humic acid (HA) plays vital roles in regulating the environmental behaviors of metals and thus their toxicity to biota. However, the inner relation between metal bioavailability to soil organisms and the presence of HA with different molecular weight (Mw) is not well documented. In this study, we separated HAs into four fractions with Mw range of 5-30k Da, and discussed their ability to alleviating the toxicity of Cd and Pb to earthworm. The bioaccumulation capacities (C_max) increased in order of: UF1<UF2<UF3<UF4, which is in line with the variations of bioavailable concentrations of Cd and Pb in soil. Variations of Mw and binding capacities of HA determine the accumulation behavior in soil solution. The unsatisfactory of biotic ligand model fitting and the differences in fractions of the total biotic ligand sites (f) in earthworm bound by Cd and Pb suggested that only free species of Cd could be considered as biological available to earthworm, while the Pb-HAs complexes have potential ability to interact with earthworm membrane. Antioxidant enzymes are effective biomarkers, and HA with lower Mw play more important roles in restricting the toxicity of soil Cd and Pb to earthworm. These results reveal the different mechanism for HA controlling metal bioavailability between Cd and Pb in soil environment.

Transcriptome analysis of genes expressed in the earthworm Eisenia fetida in response to cadmium exposure

Eisenia fetida earthworm is an ecotoxicologically important test species to monitor various pollutants. However, there is a little knowledge about the effects of cadmium (Cd) on earthworms at the transcriptional level. Firstly, we exposed E. fetida to soils supplemented with different concentrations (10, 30, 60 mg/kg soil) of Cd. Moreover, we depicted the characterization of gene expressions with E. fetida using high-throughput profiling of gene expression. In addition, a comparison of the gene expression profiles between each Cd treatment group and the control group suggested that differential expressional genes (DEGs) mainly enriched in enzyme activity, metabolism, oxidative stress, regeneration and apoptosis pathways. 8 DEGs from these pathways had been selected randomly to confirm the data of RNA-seq. Among these DEGs, six genes (metallothionein-2, phytochelatin synthase 1a, CuZn superoxide dismutase, sex determining region Y-box 2, sex determining region Y-box 4b, TP53-regulated inhibitor of apoptosis 1-like) up-regulated and 2 genes (beta-1,4-endoglucanase, apoptosis-stimulating of p53 protein 2-like) down-regulated in response to Cd exposure. The alteration of them indicated that earthworms could reduce the toxicity and bioavailability of Cd in polluted soil ecosystems through different pathways. This work lays an important foundation for linking earthworm transcriptional level with the ecological risk of Cd in soil ecosystem.

Study of Zn availability, uptake, and effects on earthworms of zinc oxide nanoparticle versus bulk applied to two agricultural soils: Acidic and calcareous

The increasing use of zinc oxide nanoparticles (ZnO NPs) in agriculture renders it necessary to evaluate their impact on soil non-target organisms. This work studies Zn availability to earthworms from the ZnO (NP and bulk) applied to two agricultural soils with a different pH at 20, 225, 500, and 1000 mg Zn kg^-1. Zn uptakes and the effects on Eisenia andrei, grown under controlled conditions, were determined. Effects were assessed at three levels: organisms, mortality, growth and reproduction; biochemical, catalase and glutathione S-transferase activities, malondialdehyde (MDA), and protein content; cellular in coelomocytes, reactive oxygen species (ROS) generation, lysosomal membrane alterations (RN) and mitochondrial dysfunction (MTT). Available Zn was 100-fold higher in acidic than in calcareous soil and did not differ among ZnO (NP or bulk). Zn in worms was auto-regulated regardless of the soil Zn concentration, pH and ZnO size. Effects on mortality and weight were observed only in the acidic soil at the highest concentration, ZnO NPs reduced survival and body weight, while ZnO bulk reduced body weight. Reproduction parameters in acidic soil were: EC50 (fecundity) 277 and 256 mg Zn kg-1 and EC50 (fertility) 177 and 179 mg Zn kg-1 for ZnO NPs and bulk, respectively, with no found NP-specific effects. No responses of enzymatic activities, MDA and MTT were detected. ROS and RN were altered in the coelomocyte cells of earthworms in the two soils, but effects depended on ZnO size suggesting nanospecific effects. Soil pH governs toxicity more than ZnO size regardless of body Zn concentration.

Evaluation of gene expression of different molecular biomarkers of stress response as an effect of copper exposure on the earthworm EIsenia Andrei

The paper reports the results of a laboratory test on the bioaccumulation and toxicological effects of sub-lethal soil concentration of copper, a widely used fungicide in organic farming, on DNA damage, a critical marker increasingly used in ecotoxicology in the earthworm Eisenia andrei. In the same experimental setting we evaluated gene expression of classical biomarker of stress induced by xenobiotic. [Heat Shock Protein 70 (HSP70) and Metallothionein (MET)], as well as genes coding for enzymes involved in detoxification of reactive oxygen species [Superoxide dismutase (SOD) and catalase (CAT)]. Additionally, expression of genes involved in the immune response were investigated: a Toll-like receptor (TLR), a receptor with cytolytic activity named Cytolytic Factor (CCF) and two antimicrobial peptides, fetidin (FET) and lysenin (LYS). Results showed significant time-dependent bioaccumulation of Cu and DNA damage at concentrations remarkably lower than those found in most agricultural soils worldwide. MET was increased as was FET and TLR. The present work gives new insights into the mechanisms of sub-lethal toxicity of copper as an environmental pollutant and in the identification of novel sub-lethal biomarkers of cellular response to the stressor such as immune response genes.

Insight into the Phytoremediation Capability of Brassica juncea (v. Malopolska): Metal Accumulation and Antioxidant Enzyme Activity

Metal hyperaccumulating plants should have extremely efficient defense mechanisms, enabling growth and development in a polluted environment. Brassica species are known to display hyperaccumulation capability. Brassica juncea (Indiana mustard) v. Malopolska plants were exposed to trace elements, i.e., cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn), at a concentration of 50 μM and were then harvested after 96 h for analysis. We observed a high index of tolerance (IT), higher than 90%, for all B. juncea plants treated with the four metals, and we showed that Cd, Cu, Pb, and Zn accumulation was higher in the above-ground parts than in the roots. We estimated the metal effects on the generation of reactive oxygen species (ROS) and the levels of protein oxidation, as well as on the activity and gene expression of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX). The obtained results indicate that organo-specific ROS generation was higher in plants exposed to essential metal elements (i.e., Cu and Zn), compared with non-essential ones (i.e., Cd and Pb), in conjunction with SOD, CAT, and APX activity and expression at the level of encoding mRNAs and existing proteins. In addition to the potential usefulness of B. juncea in the phytoremediation process, the data provide important information concerning plant response to the presence of trace metals.

Accumulation and toxicological effects of nonylphenol in tomato (Solanum lycopersicum L) plants

Nonylphenol (NP) is one of the most worrisome and ubiquitous environmental endocrine disruptors. The tomato is one of the most important agricultural plants in the world. However, little is known about the toxicological effects of NP on tomato crops or the accommodative responses of tomato plants to NP stress. Thus, in this study, relevant tests were performed using pot experiments, and they indicated that when the NP concentration in the soil was elevated from 25 mg kg-1 to 400 mg kg-1, NP was progressively accumulated by the tomato plants. The NP induced growth inhibition and a declined in the total chlorophyll content, and it aggravated membrane lipid peroxidation in tomato plants. When confronted with NP stress, the tomato plants correspondingly induced their antioxidant enzymes via both molecular and protein pathways to relieve the NP-induced oxidative stress. All the above results would be illuminating for developing strategies to address NP-induced damage to agricultural output, food quality and public health.

Caenorhabditis elegans as a tool for environmental risk assessment: emerging and promising applications for a "nobelized worm"

Caenorhabditis elegans has been an invaluable model organism in research fields such as developmental biology and neurobiology. Neurotoxicity is one of the subfields greatly profiting from the C. elegans model within biomedical context, while the corresponding potential of the organism applied to environmental studies is relevant but has been largely underexplored. Within the biomedical scope, the implication of metals and organic chemicals with pesticide activity (hereinafter designated as pesticides) in the etiology of several neurodegenerative diseases has been extensively investigated using this nematode as a primary model organism. Additionally, as a well-known experimental model bearing high sensitivity to different contaminants and representing important functional levels in soil and aquatic ecosystems, C. elegans has high potential to be extensively integrated within Environmental Risk Assessment (ERA) routines. In spite of the recognition of some regulatory agencies, this actual step has yet to be made. The purpose of this review is to discuss the major advantages supporting the inclusion of C. elegans in lower tiers of ERA. Special emphasis was given to its sensitivity to metals and pesticides, which is similar to that of other model organisms commonly used in ERA (e.g. Daphnia magna and Eisenia sp.), and to the large array of endpoints that can be tested with the species, both concerning the aquatic and the soil compartments. The inclusion of C. elegans testing may hence represent a relevant advance in ERA, providing ecologically relevant insights toward improvement of the regulatory capacity for establishing appropriate environmental protection benchmarks.

Assessment of acute toxicity and biochemical responses to chlorpyrifos, cypermethrin and their combination exposed earthworm, Eudrilus eugeniae

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In the present study, co-exposed administered pesticides induced a higher level of toxicity to Eudrilus eugeniae.

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Statistically significant changes were observed after 48 h exposure of CPF, cypermethrin and combination of the two, reflects the synergistic cumulative impact on the AChE and oxidative stress parameters in dose- dependent manner.

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Significant changes were observed in different body segments (Pre-Clitellar, Clitellar and Post-Clitellar) of earthworm in tissue specific pattern.

Recurrent application of chemical pesticides in the agricultural fields have adverse impact on flora and fauna of soil ecosystem. Earthworms immensely contribute in increasing the fertility of soil. They may act as a bioindicator for the ecotoxicological analysis of pesticide induced soil pollution. Earthworms, Eudrilus eugeniae were exposed to different concentrations of pesticides chlorpyrifos (OP), cypermethrin (a pyrethroid) and their combination for 48 h by paper contact toxicity method. The LC₅₀ for commercial grade of chlorpyrifos, cypermethrin and combined pesticides were determined as 0.165, 0.066 and 0.020 μg/cm², respectively. To assess the sub-lethal effect of these pesticides, E. eugeniae were exposed to 5% and 10% of LC₅₀ of the pesticides for 48 h. Variation in morpho-behavioural changes such as coiling, clitellar swelling, mucus release, bleeding and body fragmentation in earthworms were observed after exposure of both pesticides and their combination. Various biochemical estimations such as specific activity of acetylcholinesterase (AChE), superoxide dismutase (SOD), catalase (CAT), glutathione -S-transferase (GST); levels of lipid peroxidation (LPO) and reduced glutathione (GSH) were carried out in different body segments. Significant changes in these stress markers were observed at low and high sub-acute concentration of pesticides exposed earthworm, Eudrilus eugeniae. Such changes indicate potential health risk to E. eugeniae if exposed to the high concentrations of these pesticides accumulated in soil.

Combined toxic effects and DNA damage to two plant species exposed to binary metal mixtures (Cd/Pb)

Acute and long-term (3-, 10- and 56-day exposure) laboratory toxicity tests were carried out to assess the individual and combined toxic effects of cadmium (Cd) and lead (Pb) in Brassica oleracea and Trifolium repens. In addition to morphological parameters, this work also used comet assay to address endpoints in relation to genotoxicity. Bioaccumulation was measured to demonstrate the influence of the mixture on the concentrations of each metal in the plant. The statistical method reported by Ince et al. (1999) was used to evaluate the types of interaction between Cd and Pb in each treatment and concerning their combined effect. This study concludes that the combined effects of binary metal combinations of Cd/Pb on morphological parameters are most often additive, sometimes antagonistic and more rarely synergistic, thus extending the findings of previous publications on this subject. DNA damage analysis revealed concentration- and time-dependent interactions. Synergistic effects of mixed metals (more breaks than individually applied metals) are observed in T. repens after a short exposure. Antagonistic effects are statistically significant after 10 days-exposure, suggesting competition between metals. At 56 days, the rate of DNA damage observed in plants exposed to the Cd/Pb mixture was similar to that measured in plants exposed to lead only and was significantly lower than the rate of DNA damage induced by Cd. This supports the idea that there may be competition between metals and also strengthens the hypothesis that long-term reparation mechanisms may be implemented. Cd/Pb co-exposure does not significantly influence the bioaccumulation of each metal. It is nevertheless important to note that a statistically significant 'interaction' is not necessarily biologically relevant and should therefore be considered with caution when assessing heavy metals combined effects.

Species-dependent toxicity, accumulation, and subcellular partitioning of cadmium in combination with tetrabromobisphenol A in earthworms

Cadmium (Cd) and tetrabromobisphenol A (TBBPA) are two ubiquitous pollutants in soils and are often found together at electronic waste recycling sites. In this study, their toxicity as well as the accumulation and subcellular partitioning of Cd were determined in two ecologically different earthworms Eisenia fetida and Metaphire guillelmi exposed for 14 days to Cd (1 mg kg^-1) and TBBPA (10, 50, 100, and 500 mg kg^-1) alone and in combination. In general, Cd-TBBPA co-exposure resulted in synergistic effects in terms of acute toxicity, growth inhibition, histopathological changes in body walls, and oxidative stress responses to earthworms, moreover, M. guillelmi showed higher sensitivity than E. fetida. Principal component analysis showed that the two earthworm species differed in their biomarker expression patterns. In addition, Cd accumulation was significantly (P < 0.01) reduced in E. fetida co-exposed to TBBPA but significantly (P < 0.05 and 0.01) enhanced in M. guillelmi. The difference in bioaccumulation between the two earthworm species may be made by their different exposure routes despite the decrease of Cd bioavailability (assessed by the diffusive gradients in thin films technique) in the soils. High doses of TBBPA also altered the subcellular distribution of Cd in the earthworms. These findings demonstrate the need to include more ecologically relevant earthworm species, represented in this study by M. guillelmi, in soil risk assessments of Cd and TBBPA co-exposure.

Effects of two strobilurins (azoxystrobin and picoxystrobin) on embryonic development and enzyme activities in juveniles and adult fish livers of zebrafish (Danio rerio)

Azoxystrobin and picoxystrobin are two primary strobilurin fungicides used worldwide. This study was conducted to test their effects on embryonic development and the activity of several enzyme in the zebrafish (Danio rerio). After fish eggs were separately exposed to azoxystrobin and picoxystrobin from 24 to 144 h post fertilization (hpf), the mortality, hatching, and teratogenetic rates were measured. Additionally, effects of azoxystrobin and picoxystrobin on activities of three important antioxidant enzymes [catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD)] and two primary detoxification enzymes [carboxylesterase (CarE) and glutathione S-transferase (GST)] and malondialdehyde (MDA) content in zebrafish larvae (96 h) and livers of adult zebrafish of both sexes were also assessed for potential toxicity mechanisms. Based on the embryonic development test results, the mortality, hatching, and teratogenetic rates of eggs treated with azoxystrobin and picoxystrobin all showed significant dose- and time-dependent effects, and the 144-h LC₅₀ values of azoxystrobin and picoxystrobin were 1174.9 and 213.8 μg L^-1, respectively. In the larval zebrafish (96 h) test, activities of CAT, POD, CarE, and GST and MDA content in azoxystrobin and picoxystrobin-treated zebrafish larvae increased significantly with concentrations of the pesticides compared with those in the control. We further revealed that azoxystrobin and picoxystrobin exposure both caused significant oxidative stress in adult fish livers and the changes differed between the sexes. Our results indicated that picoxystrobin led to higher embryonic development toxicity and oxidative stress than azoxystrobin in zebrafish and the male zebrafish liver had stronger ability to detoxify than that of the females.

28-homobrassinolide regulates antioxidant enzyme activities and gene expression in response to salt- and temperature-induced oxidative stress in Brassica juncea

Brassinosteroids (BRs) are a group of naturally occurring plant steroid hormones that can induce plant tolerance to various plant stresses by regulating ROS production in cells, but the underlying mechanisms of this scavenging activity by BRs are not well understood. This study investigated the effects of 28-homobrassinolide (28-HBL) seed priming on Brassica juncea seedlings subjected to the combined stress of extreme temperatures (low, 4 °C or high, 44 °C) and salinity (180 mM), either alone or supplemented with 28-HBL treatments (0, 10⁻⁶, 10⁻⁹, 10⁻¹² M). The combined temperature and salt stress treatments significantly reduced shoot and root lengths, but these improved when supplemented with 28-HBL although the response was dose-dependent. The combined stress alone significantly increased H₂O₂ content, but was inhibited when supplemented with 28-HBL. The activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APOX), glutathione reductase (GR), dehydroascorbate reductase (DHAR) and monodehydroascorbate reductase (MDHAR) increased in response to 28-HBL. Overall, the 28-HBL seed priming treatment improved the plant’s potential to combat the toxic effects imposed by the combined temperature and salt stress by tightly regulating the accumulation of ROS, which was reflected in the improved redox state of antioxidants.

Effects of treated industrial wastewaters and temperatures on growth and enzymatic activities of duckweed (Lemna minor L.)

The efficacy of the removal of contaminants from wastewater depends on physico-chemical properties of pollutants and the efficiency of treatment plant. Sometimes, low amounts of toxic compounds can be still present in the treated sewage. In this work we considered the effects of contaminant residues in treated wastewaters and of temperatures on Lemna minor L. Treated effluent waters were collected, analyzed and used as duckweed growth medium. In order to better understand the effects of micropollutants and seasonal variation, the plants were grown under ambient conditions for seven days in summer and winter. Relative growth rate, pigments and phenolic compounds concentrations were determined, as well as the activities of catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (G-POD) and polyphenol oxidase (PPO). The pollutant concentrations varied in the two seasons, depending on the industrial and municipal activities and efficiency of treatments. Treated waters contained heavy metals, nitrogenous and phosphorus compounds, surfactants and hydrocarbons. Compared to the control, duckweed growth of treated plants decreased by 25% in summer, while in the winter due to the lower temperatures and the presence of pollutants was completely impeded. The amounts of photosynthetic pigments of treated plants were not significantly affected in the summer, while they were higher than the control in the winter when the effluent had a high nitrogen amount. High CAT activity was registered in both seasons. Treated plants had significantly lower APX activity in the summer (53%) and winter (59%) respect to the controls. The observed inhibition of the peroxidase activities in the exposed plants, confirms the controversy existing in the literature about the variability of enzymatic response in stress condition.

Earthworm coelomocyte extracellular traps: structural and functional similarities with neutrophil NETs

Invertebrate immunity is associated with natural mechanisms that include cellular and humoral elements, similar to those that play a role in vertebrate innate immune responses. Formation of extracellular traps (ETs) is a newly discovered mechanism to combat pathogens, operating not only in vertebrate leucocytes but also in invertebrate immune cells. The ET components include extracellular DNA (exDNA), antimicrobial proteins and histones. Formation of mammalian ETs depends on enzymes such as neutrophil elastase, myeloperoxidase, the citrullination of histones and protease activity. It was confirmed that coelomocytes-immunocompetent cells of the earthworm Eisenia andrei-are also able to release ETs in a protease-dependent manner, dependent or independent of the formation of reactive oxygen species and rearrangement of the cell cytoskeleton. Similar to vertebrate leukocytes (e.g., neutrophil), coelomocytes are responsible for many immune functions like phagocytosis, cytotoxicity and secretion of humoral factors. ETs formed by coelomocyte analogues to neutrophil ETs consist of exDNA, histone H3 and attached to these structures proteins, e.g., heat shock proteins HSP27. The latter fact confirms that mechanisms of ET release are conserved in evolution. The study on Annelida adds this animal group to the list of invertebrates capable of ET release, but most importantly provides insides into innate mechanisms of ET formation in lower animal taxa.

Study on the influential biochemical indices of Cd(II) on Eisenia fetida in oxidative stress by principal component analysis in the natural soil

With the aggravation of heavy metal pollution in soil, the individual heavy metal content monitoring cannot predict the true effects of harmful substances on the ecosystems. Thus, the effective biological evaluation system should be established to assess the pollution risk caused by heavy metal. Earthworms are widely distributed in the soil, and at the bottom of the food chain, the changes of biochemical indices play an important role in the early warning for heavy metal pollution. Principal component analysis (PCA) is a statistical method that derives several independent principal components from the original variable based on retaining the information as much as possible. This paper is aimed at finding out and analyzing the key monitoring factors related to Cd²⁺ on the earthworm Eisenia fetida in oxidative stress. The Cd²⁺ stress concentrations were set at 0, 1, 10, 20, 100, 200, 400, and 800 mg kg^-1, and the post-clitellum segment of earthworm was chosen to determine TP, POD, SOD, GST, GPX, CAT, MDA, VE, and AChE. The results showed that the main bioindicators associated with oxidative stress reaction were GST, POD, and MDA at the exposure time of 10 days; at 20 days GPX, MDA, and AChE; at 30 days CAT, TP, and GPX; CAT, MDA, and SOD at 40th day. These results indicated that PCA can quickly, effectively, directly, and scientifically select biomarkers of oxidative stress induced by Cd and improve the accuracy and scientificity of earthworm as a biomarker in monitoring and early warning for heavy metal-contaminated soil.

Nitric oxide induces rice tolerance to excessive nickel by regulating nickel uptake, reactive oxygen species detoxification and defense-related gene expression

Soil contamination with nickel (Ni) is a persistent threat to crop production worldwide. The present study examined the putative roles of nitric oxide (NO) in improving Ni-tolerance in rice. Our findings showed that application of exogenous sodium nitroprusside (SNP), a NO donor, significantly improved the growth performance of rice seedlings when grown under excessive Ni. The enhanced Ni-tolerance of rice prompted by SNP could be ascribed to its ability to regulate Ni uptake, decrease Ni-induced oxidative stress as evidenced by reduced levels of hydrogen peroxide, malondialdehyde, and electrolyte leakage in Ni-stressed plants. The positive roles of NO against Ni-toxicity also reflected through its protective effects on photosynthetic pigments, soluble proteins and proline. SNP also boosted antioxidant capacity in Ni-stressed plants by maintaining increased levels of ascorbate, enhanced activities of ROS-detoxifying enzymes, particularly peroxidase (POD) and catalase (CAT) in both roots and shoots compared with Ni-stressed alone plants. Moreover, SNP treatment also upregulated the transcript levels of CAT, POD, ascorbate peroxidase, glutathione reductase and superoxide dismutase genes in shoots under Ni-stress. Using different sulfide compounds and NO scavenger cPTIO, we also provided evidence that NO, rather than other byproducts of SNP, contributed to the improved performance of rice seedlings under Ni-stress. Collectively, our results conclude that exogenous SNP-mediated modulation of endogenous NO enhanced rice tolerance to Ni-stress by restricting Ni accumulation, maintaining photosynthetic performance and reducing oxidative damage through improved antioxidant system, thereby suggesting NO as an effective stress regulator in mitigating Ni-toxicity in economically important rice, and perhaps in other crop plants.

Protective role of metallothionein during regeneration in Eisenia andrei exposed to cadmium

Lumbricid earthworms are often exposed to simultaneous action of various environmental stressors like soil contamination, temperature fluctuation or predators' attacks, which may induce extrusion of coelomocyte-containing coelomic fluid or loss of tail segments. If the injuries are not lethal, renewal of the immune-competent cells and soluble components of coelomic fluid and/or the regeneration of tail segments occurs. The aim of our investigations was to test the hypothesis that exposure of adult earthworms Eisenia andrei to cadmium-polluted soil at room temperature (RT) and/or low temperature (6°C) have adverse effects on restoration of experimentally depleted coelomocytes or on regeneration of amputated posterior segments. Intact control earthworms and their experimental counterparts subjected to electrostimulation-induced coelomocyte depletion or surgical amputation of posterior segments were maintained either in control soil or in soil spiked with cadmium chloride (500mg/kg air-dried soil) at RT or 6°C. Four weeks after the beginning of experiments, cadmium accumulation in earthworm bodies was significantly lower at 6°C than at room temperature. The numbers of restored cells and fluorophore contents were hardly affected by temperature or cadmium. However, cocoon production was reduced by cadmium and completely abolished at 6°C and regeneration of amputated posterior segments was inhibited in cold but was enhanced by cadmium exposure at RT. Independently on the temperature, the 4-week cadmium exposure of adult earthworms was connected with significantly upregulated expression of Cd-metallothionein (but not of catalase, lysenin and phytochelatin) in coelomocytes.

Effect of earthworms on growth, photosynthetic efficiency and metal uptake in Brassica juncea L. plants grown in cadmium-polluted soils

The present study has been carried out to examine the role of earthworms in phytoremediation of Cd and its effect on growth, pigment content, expression of genes coding key enzymes of pigments, photosynthetic efficiency and osmoprotectants in Brassica juncea L. plants grown under cadmium (Cd) metal stress. The effect of different Cd concentrations (0.50, 0.75, 1.0, 1.25 mM) was studied in 30 and 60-day-old plants grown in soils containing earthworms. It was observed that earthworm inoculation showed stimulatory effect on phytoremediation capacity and Cd uptake has increased by 49% (in 30-day-old plants) and 35% (in 60-day-old plants) in shoots and 13.3% (in 30-day-old plants) and 10% (in 60-day-old plants) in roots in 30 and 60-day-old plants in Cd (1.25 mM) treatments. Plant growth parameters such as root and shoot length, relative water content and tolerance index were found to increase in the presence of earthworms. Recovery in photosynthetic pigments (chlorophyll and carotenoid) and gas exchange parameters, i.e. net photosynthetic rate (P _n ), stomatal conductance (G _s ), intercellular CO₂ concentration (C _i ) and transpiration rate (E _t ), was observed after earthworm's supplementation. Modulation in expression of key enzymes for pigment synthesis, i.e. chlorophyllase, phytoene synthase, chalcone synthase and phenylalanine ammonia lyase, was also observed. The results of our study revealed that earthworms help to mitigate the toxic effects produced by Cd on plant growth and photosynthetic efficiency along with enhanced phytoremediation capacity when co-inoculated with Cd in soil.

Effects of bifenthrin exposure in soil on whole-organism endpoints and biomarkers of earthworm Eisenia fetida

In this study, toxic effects of bifenthrin in soil on earthworms were evaluated by acute and chronic toxic endpoints combined with a set of biomarkers. Bifenthrin was moderately toxic in 72-h filter paper test and low toxic in 14-d soil test. The exposure of earthworms to bifenthrin-polluted soil for 8 weeks showed that cocoons were inhibited by high dose of bifenthrin, and larvae were stimulated by low dose but inhibited by high dose of bifenthrin. Furthermore, 28-d soil test on the responses of enzymes associated with antioxidation and detoxification in worms showed that peroxidase (POD) was stimulated by bifenthrin, superoxide dismutase (SOD) inhibited in the early period but stimulated in the later period, glutathione S- transferase (GST) inhibited in the later period, and ethoxyresorufin-O-deethylase (EROD) inhibited at day 3 but markedly stimulated at day 28 at high dose. The different responses of these indexes indicated that multi indexes should be jointly taken into account for comprehensive evaluation of the environmental risk of contaminants in soil.

Oxidative stress responses and insights into the sensitivity of the earthworms Metaphire guillelmi and Eisenia fetida to soil cadmium

Soil toxicological tests are commonly performed using Eisenia fetida as the standard earthworm species, but it is tolerant to a wide range of pollutants. Therefore, the inclusion of susceptible species is crucial for the accurate estimation of soil contamination. In this study, we examined the sensitivity to soil cadmium (Cd) of anecic Metaphire guillelmi and epigeic E. fetida by measuring multiple indexes of oxidative stress. Using subcellular partitioning analysis, we further elucidated the inherent mechanism underlying the species-specific sensitivity of the two earthworm species. Among the battery of biochemical indexes, reactive oxygen species and protein carbonyl groups served as sensitive biomarkers. According to their respective response thresholds, M. guillelmi was more sensitive than E. fetida and they differed in their dose-response relationships. In E. fetida, the activities of three antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST), exhibited a hormesis-like U-shaped dose-response relationship, while in M. guillelmi SOD, glutathione peroxidase (an analogue of CAT) and GST showed an inverted U-shaped relationship. The concentrations of Cd in the subcellular fractions and whole body of the earthworms well fit (R²>0.9) a saturation model versus bioavailable Cd concentrations determined by the diffusive gradients in thin films technique. Despite the lower accumulation capacity of M. guillelmi, the Cd-binding capacity (C_max) of its subcellular heat-stable protein fraction, the so-called biologically detoxified metal pool, was 2.7 times lower than that of E. fetida, whereas the Cd binding affinity (logK) of its heat-denatured protein fraction, i.e. the metal-sensitive fraction, was 3.0 times higher, which accounted for the high susceptibility of M. guillelmi to soil Cd. Our results suggest that because of their sensitivity, as exemplified by M. guillelmi, native earthworm species should be taken into account in soil risk assessments to avoid underestimation of the toxicity of various pollutants.

Oxidative stress of imidaclothiz on earthworm Eisenia fetida

Imidaclothiz, a kind of neonicotinoid insecticides, is developed as a commercial pesticide in China and used for the control of sucking and biting insects, including aphids, whiteflies, beetles and some Lepidoptera species as well. In recent years, more and more attention has been focused on the adverse effects of neonicotinoid insecticides on non-target organisms. In this study, inhibition effects of imidaclothiz and recovery capacity of molecular biomarkers (GST, CE, CAT, SOD and POD activity, and DNA damage) in earthworms were detected for the first time. Earthworms were exposed to imidaclothiz (0.3 and 1.0mgkg^-1) for 28days, and then transferred to the clean artificial soil for 28days. Regarding enzyme activities, GST, CE, CAT and POD were inhibited following exposure to imidaclothiz at one or more sample times, while SOD was not affected. After transferring to the clean artificial soil, POD continued to be significantly inhibited till sample time 35days at 0.3mg/kg^-1. For GST, CE, CAT and SOD, activities of them were significantly increased compared to those of the control during the recovery period. The olive tail moments (OTM) in comet assay, as an indication of DNA damage, were significantly increased compared to the control after treatment and then decreased during the recovery period. These results suggested that imidaclothiz induced oxidative damage on earthworms which caused damage to vital macromolecules including DNA. However, the recovery changes of all tested biomarkers following the transfer to clean soil suggested the tested earthworm recovery from imidaclothiz exposure.

Study on the influential factors of Cd(2+) on the earthworm Eisenia fetida in oxidative stress based on factor analysis approach

When earthworms are exposed to pollutants, their antioxidant system will have responses immediately. Consequently earthworms are widely used to monitor various pollutants as a sensitive bio-indicator. However, there are a large number of indices associated with the oxidative stress response. Finding out the key monitoring indices in the stress process becomes a practical demand of the pollution monitoring and warning process. Factor analysis approach is a statistical method that uses a few factors to replace many original factors. This paper is aimed at analyzing and sorting factors related to Cd(2+) on the earthworm Eisenia fetida in oxidative stress. We studied two groups, the short-term test and the long-term test. The former test lasted for ten days, removing an earthworm every day for analysis; The latter test lasted for 30 days, taking out an earthworm every ten days. The Cd(2+) concentration was set at 0, 50, 100, 125, 250 and 500 mg kg(-1), post-clitellum segments of earthworms were chosen to determine SOD, POD, GPX, GST, CAT, VE, MDA and AChE. The results showed that in the short-term group, the main bioindicator associated with oxidative stress reaction was CAT at the exposure time of 1-3 days, at 4-5 days MDA, 6-7 days POD, and GST and GPX at 8th day, CAT at 9-10 days. While with the long-term test, the main bioindicator associated with oxidative stress reaction was GPX.

Conservative Mechanisms of Extracellular Trap Formation by Annelida Eisenia andrei: Serine Protease Activity Requirement

Formation of extracellular traps (ETs) capturing and immobilizing pathogens is now a well-established defense mechanism added to the repertoire of vertebrate phagocytes. These ETs are composed of extracellular DNA (extDNA), histones and antimicrobial proteins. Formation of mouse and human ETs depends on enzymes (i) facilitating decondensation of chromatin by citrullination of histones, and (ii) serine proteases degrading histones. In invertebrates, initial reports revealed existence of ETs composed of extDNA and histones, and here we document for the first time that also coelomocytes, immunocompetent cells of an earthworm Eisenia andrei, cast ETs which successfully trap bacteria in a reactive oxygen species (ROS)-dependent and -independent manner. Importantly, the formation of ETs was observed not only when coelomocytes were studied ex vivo, but also in vivo, directly in the earthworm coelom. These ETs were composed of extDNA, heat shock proteins (HSP27) and H3 histones. Furthermore, the formation of E. andrei ETs depended on activity of serine proteases, including elastase-like activity. Moreover, ETs interconnected and hold together aggregating coelomocytes, a processes proceeding encapsulation. In conclusion, the study confirms ET formation by earthworms, and unravels mechanisms leading to ET formation and encapsulation in invertebrates.

Exogenous proline mediates alleviation of cadmium stress by promoting photosynthetic activity, water status and antioxidative enzymes activities of young date palm (Phoenix dactylifera L.)

The ability of exogenous compatible solutes, such as proline, to counteract cadmium (Cd) inhibitory effects in young date palm plants (Phoenix dactylifera L. cv Deglet Nour) was investigated. Two-year-old date palm plants were subjected for five months at different Cd stress levels (0, 10 and 30 mg CdCl2 kg(-1) soil) whether supplied or not with exogenous proline (20mM) added through the irrigation water. Different levels of Cd stress altered plant growth, gas exchanges and chlorophyll content as well as water status, but at different extent among them. In contrast, an increase of antioxidant enzymes activities of Cd-treated plants in association with high amounts of proline content, hydrogen peroxide (H2O2), thiobarbituric acid reactive substances (TBARS) and electrolyte leakage (EL) were observed. Interestingly, exogenous proline mitigated the adverse effects of Cd on young date palm. Indeed, it alleviated the oxidative damage induced by Cd accumulation and established better levels of plant growth, water status and photosynthetic activity. Moreover, proline-treated plants showed high antioxidant enzymes activities (superoxide dismutase, catalase and glutathione peroxydase) in roots and leaves as compared to Cd-treated plants.

Biological responses of wheat (Triticum aestivum) plants to the herbicide simetryne in soils

The rotation of rice and wheat is widely used and highly endorsed, and simetryne (s-triazine herbicide) is one of the principal herbicides widely used in this rotation for weed and grass control. However, little is known regarding the mechanism of the ecological and physiological effects of simetryne on wheat crops. In this study, we performed a comprehensive investigation of crop response to simetryne to elucidate the accumulation and phytotoxicity of the herbicide in wheat crops. Wheat plants exposed to 0.8 to 8.0mgkg(-1) simetryne for 7 d exhibited suppressed growth and decreased chlorophyll content. With simetryne concentration in the soil varied from 0.8mgkg(-1) to 8.0mgkg(-1), simetryne was progressively accumulated by the wheat plants. The accumulation of simetryne in the wheat plants not only induced the over production of ROS and injured the membrane lipids but also stimulated the production of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX), glutathione reductase (GR) and glutathione S-transferase (GST). A test of enzymatic activity and gene expression illustrated that the wheat plants were wise enough to motivate the antioxidant enzymes through both molecular and physiological mechanisms to alleviate the simetryne-induced stress. This study offers an illuminating insight into the effective adaptive response of the wheat plants to the simetryne stress.

Unraveling the role of dark septate endophyte (DSE) colonizing maize (Zea mays) under cadmium stress: physiological, cytological and genic aspects

A growing body of evidence suggests that plant root-associated fungi such as dark septate endophytes (DSE) can help plants overcome many biotic and abiotic stresses, of great interest is DSE-plant metal tolerance and alleviation capabilities on contaminated soils. However, the tolerance and alleviation mechanisms involved have not yet been elucidated. In the current study, the regulation and physiological response of Zea mays to its root-associated DSE, Exophiala pisciphila was analyzed under increased soil Cd stress (0, 10, 50, 100 mg kg⁻¹). Under Cd stress, DSE inoculation significantly enhanced the activities of antioxidant enzymes and low-molecular weight antioxidants, while also inducing increased Cd accumulation in the cell wall and conversion of Cd into inactive forms by shoot and root specific regulation of genes related to metal uptake, translocation and chelation. Our results showed that DSE colonization resulted in a marked tolerance to Cd, with a significant decrease in cadmium phytotoxicity and a significant increase in maize growth by triggering antioxidant systems, altering metal chemical forms into inactive Cd, and repartitioning subcellular Cd into the cell wall. These results provide comprehensive evidence for the mechanisms by which DSE colonization bioaugments Cd tolerance in maize at physiological, cytological and molecular levels.

Antioxidant defense gene analysis in Brassica oleracea and Trifolium repens exposed to Cd and/or Pb

This study focused on the expression analysis of antioxidant defense genes in Brassica oleracea and in Trifolium repens. Plants were exposed for 3, 10, and 56 days in microcosms to a field-collected suburban soil spiked by low concentrations of cadmium and/or lead. In both species, metal accumulations and expression levels of genes encoding proteins involved and/or related to antioxidant defense systems (glutathione transferases, peroxidases, catalases, metallothioneins) were quantified in leaves in order to better understand the detoxification processes involved following exposure to metals. It appeared that strongest gene expression variations in T. repens were observed when plants are exposed to Cd (metallothionein and ascorbate peroxidase upregulations) whereas strongest variations in B. oleracea were observed in case of Cd/Pb co-exposures (metallothionein, glutathione transferase, and peroxidase upregulations). Results also suggest that there is a benefit to use complementary species in order to better apprehend the biological effects in ecotoxicology.

Jasmonic Acid Modulates the Physio-Biochemical Attributes, Antioxidant Enzyme Activity, and Gene Expression in Glycine max under Nickel Toxicity

In present study, we evaluated the effects of Jasmonic acid (JA) on physio-biochemical attributes, antioxidant enzyme activity, and gene expression in soybean (Glycine max L.) plants subjected to nickel (Ni) stress. Ni stress decreases the shoot and root length and chlorophyll content by 37.23, 38.31, and 39.21%, respectively, over the control. However, application of JA was found to improve the chlorophyll content and length of shoot and root of Ni-fed seedlings. Plants supplemented with JA restores the chlorophyll fluorescence, which was disturbed by Ni stress. The present study demonstrated increase in proline, glycinebetaine, total protein, and total soluble sugar (TSS) by 33.09, 51.26, 22.58, and 49.15%, respectively, under Ni toxicity over the control. Addition of JA to Ni stressed plants further enhanced the above parameters. Ni stress increases hydrogen peroxide (H2O2) by 68.49%, lipid peroxidation (MDA) by 50.57% and NADPH oxidase by 50.92% over the control. Supplementation of JA minimizes the accumulation of H2O2, MDA, and NADPH oxidase, which helps in stabilization of biomolecules. The activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) increases by 40.04, 28.22, 48.53, and 56.79%, respectively, over the control in Ni treated seedlings and further enhancement in the antioxidant activity was observed by the application of JA. Ni treated soybean seedlings showed increase in expression of Fe-SOD by 77.62, CAT by 15.25, POD by 58.33, and APX by 80.58% over the control. Nevertheless, application of JA further enhanced the expression of the above genes in the present study. Our results signified that Ni stress caused negative impacts on soybean seedlings, but, co-application of JA facilitate the seedlings to combat the detrimental effects of Ni through enhanced osmolytes, activity of antioxidant enzymes and gene expression.

Exposure to 17β-Oestradiol Induces Oxidative Stress in the Non-Oestrogen Receptor Invertebrate Species Eisenia fetida

Background

The environmental impacts of various substances on all levels of organisms are under investigation. Among these substances, endocrine-disrupting compounds (EDCs) present a threat, although the environmental significance of these compounds remains largely unknown. To shed some light on this field, we assessed the effects of 17β-oestradiol on the growth, reproduction and formation of free radicals in Eisenia fetida.

Methodology/Principal Findings

Although the observed effects on growth and survival were relatively weak, a strong impact on reproduction was observed (50.70% inhibition in 100 μg/kg of E₂). We further demonstrated that the exposure of the earthworm Eisenia fetida to a contaminant of emerging concern, 17β-oestradiol (E₂), significantly affected the molecules involved in antioxidant defence. Exposure to E₂ results in the production of reactive oxygen species (ROS) and the stimulation of antioxidant systems (metallothionein and reduced oxidized glutathione ratio) but not phytochelatins at both the mRNA and translated protein levels. Matrix-assisted laser desorption/ionization (MALDI)-imaging revealed the subcuticular bioaccumulation of oestradiol-3,4-quinone, altering the levels of local antioxidants in a time-dependent manner.

Conclusions/Significance

The present study illustrates that although most invertebrates do not possess oestrogen receptors, these organisms can be affected by oestrogen hormones, likely reflecting free diffusion into the cellular microenvironment with subsequent degradation to molecules that undergo redox cycling, producing ROS, thereby increasing environmental contamination that also perilously affects keystone animals, forming lower trophic levels.

Effect of Heavy Metals in Plants of the Genus Brassica

Several species from the Brassica genus are very important agricultural crops in different parts of the world and are also known to be heavy metal accumulators. There have been a large number of studies regarding the tolerance, uptake and defense mechanism in several of these species, notably Brassica juncea and B. napus, against the stress induced by heavy metals. Numerous studies have also been published about the capacity of these species to be used for phytoremediation purposes but with mixed results. This review will focus on the latest developments in the study of the uptake capacity, oxidative damage and biochemical and physiological tolerance and defense mechanisms to heavy metal toxicity on six economically important species: B. juncea, B. napus, B. oleracea, B. carinata, B. rapa and B. nigra.