Oxidative Stress In Earthworms Research Articles

Comparative study of fenpropathrin and its main metabolite in soil-earthworm microcosms: Toxicity, degradation, transcriptome, and oxidative stress

This study comprehensively investigated the comparative acute toxicities, degradation, transcriptome, and oxidative stress induction of fenpropathrin (FEN) and its main metabolite 3-phenoxybenzoic acid (3-PBA)in soil-earthworm microcosms. FEN degradation half-life ranged from 19.09 to 28.52 days, and the peak-shaped trends of 3-PBA were also observed in different soil types. The LC50 values of FEN and 3-PBA were 12.75 and 7.49 μg/cm2, respectively, suggesting that 3-PBA was more toxic to earthworms. Furthermore, the sub-lethal toxicities indicated that 3-PBA exerted more prominent alterations in protein content, enzyme activity, lipid peroxidation, and oxidative stress in earthworms. Additionally, integrated biomarker response evaluations indicated that 3-PBA induced more prominent sub-lethal toxicity in earthworms than FEN. Finally, exposure to FEN and 3-PBA resulted in distinct differentially expressed genes (DEGs) in earthworms. Enrichment analysis revealed that these DEGs were predominantly enriched in purine metabolism and bile secretion pathways in earthworms. Moreover, the p53 signaling pathway, cell cycle, DNA replication, drug metabolism, and pyrimidine metabolism were also enriched in earthworms after exposure to FEN and 3-PBA. These results suggested that FEN and 3-PBA induced varying toxicities in earthworms. This study highlighted the systemic differences in the toxicities, degradation, transcriptome, and oxidative stress induction between FEN and 3-PBA in soil-earthworm microcosms. Our findings could be used for a comprehensive risk assessment of FEN and 3-PBA in the soil ecosystem.

Combined exposure to decabromodiphenyl ether and nano zero-valent iron aggravated oxidative stress and interfered with metabolism in earthworms

Decabromodiphenyl ether (BDE-209) is a common brominated flame retardant in electronic waste, and nano zero-valent iron (nZVI) is a new material in the field of environmental remediation. Little is known about how BDE-209 and nZVI combined exposure influences soil organisms. During the 28 days study, we determined the effects of single and combined exposures to BDE-209 and nZVI on the oxidative stress and metabolic response of earthworms (Eisenia fetida). On day 7, compared to CK, malondialdehyde (MDA) content increased in most combined exposure groups. To remove MDA and reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activities were induced in most combined exposure groups. On day 28, compared to CK, the activities of SOD and CAT were inhibited, while POD activity was significantly induced, indicating that POD plays an important role in scavenging ROS. Combined exposure to BDE-209 and nZVI significantly affected amino acid biosynthesis and metabolism, purine metabolism, and aminoacyl-tRNA biosynthesis pathways, interfered with energy metabolism, and aggravated oxidative stress in earthworms. These findings provide a basis for assessing the ecological impacts of using nZVI to remediate soils contaminated with BDE-209 from electronic waste.

Speciation, bioaccumulation, and toxicity of the newly deposited atmospheric heavy metals in soil-earthworm (Eisenia fetida) system near a large copper smelter

The speciation, bioaccumulation, and toxicity of the newly deposited atmospheric heavy metals in the soil-earthworm (Eisenia fetida) system were investigated by a fully factorial atmospheric exposure experiment using soils exposed to 0.8-year and 1.8-year atmospheric depositions. The results shown that the newly deposited metals (Cu, Cd, and Pb) primarily accumulated in the topsoil (0–6 cm) and were present as the highly bioavailable speciation. They can migrate further to increase the concentrations of Cu, Cd, and Pb in soil solution of the deeper layer (at 10 cm) by 12 %–436 %. Earthworms tended to preferentially accumulate the newly deposited metals, which contributed 10 %–61 % of Cu, Cd, and Pb in earthworms. Further, for the unpolluted and moderately polluted soils, the newly deposited metals induced the significant oxidative stress in earthworms, resulting in significant increases in antioxidant enzyme activities (SOD, CAT, and GSH-Px). No significant differences were observed in the levels of heavy metals in soil solutions, bioaccumulation, and enzyme activities in earthworms exposed to 0.8-year and 1.8-year depositions, indicating the bioavailability of atmospheric metals deposited into soils was rapidly decreased with time. This study highlights the high bioaccumulation and toxicity of heavy metals to earthworm from the new atmospheric deposition during the earthworm growing period.

Effects of polyethylene microplastics stress on soil physicochemical properties mediated by earthworm Eisenia fetida.

Microplastics (MPs) are widely distributed in soil environments, but their ecological risks are not fully understood. To fill this knowledge gap, incubation experiments were conducted to explore the physiological response of Eisenia foetida (E. fetida) to polyethylene MP stress and its effects on soil physicochemical properties. E. fetida was incubated in soils amended with MPs of two particle sizes (13μm and 130μm) at six concentrations (0, 1, 3, 6, 10 and 20g MPs·kg-1 soil) under laboratory conditions. The toxicity of 13μm MPs on the growth and survival of E. fetida was greater than that of 130μm MPs. Excessive reactive oxygen species accumulation induced by high MP concentrations decreased superoxide dismutase activity and increased malondialdehyde content. Soil pH increased significantly in the 130μm treatments. MPs increased the contents of soil organic carbon and available potassium. However, the presence of MPs did not significantly alter available phosphorus or nitrate nitrogen content. MP contamination in soil may have adverse impacts on the growth of earthworms, induce oxidative stress in earthworms, and change soil physicochemical properties. In addition, the effects of MPs are size-dependent and dose-dependent. This study provides new evidence for the ecological risks of MP pollution in the earthworm-soil systems.

Comparative Toxicological Effects of Perfluorooctane Sulfonate and Its Alternative 6:2 Chlorinated Polyfluorinated Ether Sulfonate on Earthworms.

High levels of 6:2 chlorinated polyfluorinated ether sulfonate (F-53B), which is a substitute for perfluorooctane sulfonate (PFOS), are detected in various environmental matrices, wildlife, and humans. Chlorinated polyfluorinated ether sulfonate has received increased attention due to its potential risk to ecosystems. However, its toxicity in the soil organisms remains unclear. In the present study, a comparative investigation was conducted on the toxicities of 6:2 Chlorinated polyfluorinated ether sulfonate (F-53B) and PFOS to the earthworm Eisenia. fetida. F-53B was significantly more acutely toxic to earthworms than PFOS, with median lethal concentrations of 1.43 and 1.83 mmol/kg dry soil (~816 and 984 mg/kg dry soil), respectively. Although both F-53B and PFOS, at 0.4 mmol/kg dry soil (=228 and 215 mg/kg dry soil) caused oxidative stress in earthworms, as evidenced by increased superoxide dismutase, peroxidase, and catalase activities as well as malondialdehyde level, the stress caused by F-53B was higher than that caused by PFOS. In transcriptomic and metabolomic studies, negative effects of PFOS and F-53B were observed on several metabolic processes in earthworms, including protein digestion and amino acid absorption, lipid metabolism, and the immune response. Compared with PFOS, F-53B exhibited a weaker disruption of lipid metabolism, comparable potency for toxicity to the immune response, and a stronger potency in extracellular matrix destruction along with apoptosis and ferroptosis induction. Hence, our data suggest that F-53B is more toxic than PFOS to earthworms. The findings provide some new insights into the potential toxicity of F-53B to soil organisms. Environ Toxicol Chem 2024;43:170-181. © 2023 SETAC.

The influence of ambient temperature and polyphenols from plant leaves on growth and the response to oxidative and nitrosative stress in African nightcrawler earthworm, Eudrilus eugeniae (Kinberg, 1867).

Earthworms are one of the organisms that may be affected by climate change. Finding ways to help them deal with this problem is, therefore, important and necessary. The objective of this experiment was to understand the influence of ambient temperature and polyphenols from mulberry (Morus alba L.), almond (Terminalia catappa L.) and cassava (Manihot esculenta (L.) Crantz) leaveson growth, ferric reducing antioxidant power (FRAP), malondialdehyde (MDA), hydrogen peroxide (H2O2) and nitric oxide (NO) concentrationof the African night crawler, Eudrilus eugeniae (Kinberg, 1867) earthworm. The earthworms were cultured in 2 different conditions of ambient temperature, and in 4 types of substrate i.e. dairy cow faeces (BS), dairy cow faeces + mulberry leaves (BS + MA), almond leaves (BS + TC), and cassava leaves (BS + ME), respectively. At week 2 of the experiment, body weight, FRAP, MDA, H2O2 and NO were measured in the earthworms. It was found that the body weight gain (BWG) of the earthworms cultured in BS at cyclical temperature (26+1oC-34+1oC-26+1oC,CyT) was higher than the constant temperature (26 ± 1°C, CoT) (P < 0.05). FRAP of earthworms cultured in BS + TC was higher than in other groups (P < 0.05). MDA of earthworms cultured at CyT was higher than ambient temperature at CoT (P < 0.05). At CyT, the MDA of earthworms cultured in BS + MA was higher than that of those cultured in BS, BS + TC and BS + ME (P < 0.05). NO of earthworms at CoT was higher than at CyT(P < 0.05). At CoT, the NO of earthworms cultured in BS + TC was lower than that of those cultured in BS + MA and BS + ME (P < 0.05). H2O2 of earthworms at CoT was higher than those at CyT (P < 0.05). The level of H2O2 of the earthworms cultured in BS + ME at CoT was higher than at CyT (P < 0.05). In addition, the H2O2 of earthworms cultured in both ambient temperatures and cultured in BS + MA was higher than the other groups (P < 0.05). These phenomena indicated that low and high ambient temperatures induced nitrosative and oxidative stress in earthworms, respectively. Mulberry leaves are toxic to earthworms. On the other hand, almond leaves could reduce nitrosative stress in earthworms. While at the CoT, cassava leaves induced the production of H2O2 in the earthworms.

Oxidative potential of heavy-metal contaminated soil reflects its ecological risk on earthworm

The ecological risk of heavy metal-contaminated soil is usually evaluated by its oxidative stress on terrestrial animals, which are vulnerable to the impact of individual differences of animals and environmental conditions. Oxidative potential (OP) is the potential of particles to induce the formation of reactive oxygen species (ROS). In this study, OP of the in situ contaminated soils collected from an industrial site (i.e., 64.5–7783 mg/kg of Cu, 54.9–397 mg/kg of Pb, 278–2085 mg/kg of Zn and 0.615–121 mg/kg of Cd) were measured as 38.0–60.1 pmol/min/mg, and the water extractable Cu, Pb, Zn, and Cd in soils have been proved to contribute 89%–98% to OP. Oxidative stress in earthworms (Eisenia fetida) caused by the industrial contaminated soils can be reflected by the biomarkers such as 8-hydroxy-2′-deoxyguanosine, metallothionein, and antioxidant enzymes, and a negative correlation presents between the comprehensive biomarker response index and the OP of soils (r = −0.979, p < 0.01). This is the first time to propose a dose-response relationship between OP and oxidative stress. Metabolomic analysis also verified that the regulation of four ROS-related metabolites (i.e., l-pipecolate, 1-methylhistidine, 5-methoxytryptamine, and xanthosine) in earthworms treated with contaminated soil were directly correlated with OP values. These results indicate that OP can be used as an indicator for ecological risk assessment of heavy metal-contaminated soil, which provides a fast, stable and easily testable chemical method.

Metsulfuron-methyl induced physiological, behavioural and biochemical changes in exotic (Eisenia fetida) and indigenous (Metaphire posthuma) earthworm species: Toxicity and molecular docking studies

In modern agricultural practices, Metsulfuron-methyl (sulfonylurea herbicide) is widely employed to inhibit the weeds and grasses. The current study revealed that Metaphire posthuma was more sensitive than Eisenia fetida against Metsulfuron-methyl (MSM). The LC50 values for Eisenia fetida were 2884.08 mgkg−1 and 1871.18 mgkg−1after 7 and 14 days, respectively. Similarly, the LC50 values for Metaphire posthuma were 2449.34 mgkg−1 and 1673.10 mgkg−1for 7 and 14 days, respectively. Reproduction parameters were significantly decreased at 400 (T3), 800 (T4) and 1600 (T5) mgkg−1 MSM in E. fetida whereas at 200 (T2), 400 (T3), 800 (T4), 1600 (T5) mgkg−1 MSM in M. posthuma. EC50 of avoidance response for 20% MSM by E. fetida and M. posthuma was recorded 901.76 mgkg−1and 544.21 mgkg−1 respectively. Malondialdehyde (MDA) content along with guaiacol peroxidase (POD), catalase (CAT) and superoxide dismutase (SOD) activities were initially increased up to 21st day by MSM, inducing a slight oxidative stress in earthworms and recovered to control level on 28th day. The GST activities were continuously stimulated throughout the exposure period and enhance the detoxification effect thereby preventing the earthworms from toxins. Molecular docking studies indicated that hydrogen bonding and hydrophobic interactions are key forces in binding between MSM and SOD/CAT/POD/GST. As a result, this is the first study to be reported on physiological, behavioural and biochemical changes in two different earthworm species under the exposure of sulfonyl urea herbicide.

Ecotoxicological Effects of Bimetallic PdNi/MWCNT and PdCu/MWCNT Nanoparticles onto DNA Damage and Oxidative Stress in Earthworms.

Bimetallic nanoparticles are synthesized using two different metal elements and used recently in many fields. However, limited studies related to the ecotoxic effects of nanoparticles available in the literature. The purpose of this study is to synthesize and characterize bimetallic PdCu/MWCNT and PdNi/MWCNT NPs and investigate their ecotoxic effects on earthworms. For this purpose, we injected approximately 20 µL of various concentrations of bimetallic PdCu/MWCNT and PdNi/MWCNT NPs (1, 10, 100, 1000, and 2000mg/L) into the coelomic space of earthworms. We evaluated survival rate, malformations, reactive oxygen species (ROS) level, 8-OHdG content, and histopathological changes in earthworms at the 48th hour after exposure. PdCu/MWCNT and PdNi/MWCNT NPs were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) pattern, and Raman-scattering spectroscopy. Toxicological examinations showed that PdCu/MWCNT NPs reduced the survival rate of earthworms (2000mg/L, 84%) and caused various malformations (various lesions, thinning, swelling, and rupture), but nonsignificant effects of survival rate and malformations were observed in earthworms using PdNi/MWCNT NPs. The histopathological examinations of earthworm tissues exposed with PdNi/MWCNT determined that tissues in all treatment groups had a normal histological appearance. However, at a concentration of 2000mg/L of PdCu/MWCNT NPs, atrophy in the longitudinal muscle layer and less degenerative cells in the epidermis layer were observed in earthworm tissues. It was determined that PdNi/MWCNT and PdCu/MWCNT NPs caused significant increases in ROS levels and 8-OHdG activity in earthworm tissues after 48h. Finally, our results demonstrated that the toxicity of PdNi/MWCNT NPs was detected to be lower than PdCu/MWCNT NPs. However, both nanoparticles may pose a toxicological risk at high concentrations (1000 and 2000mg/L). These findings will provide valuable information to studies on the use of PdNi/MWCNT NPs in wastewater treatment systems, industrial and medical fields, which have been determined to have less ecotoxicological risk.

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.

Study of cadmium (Cd)-induced oxidative stress in Eisenia fetida based on mathematical modelling

As a sensitive biological indicator, earthworms are widely used to monitor various pollutants of soil and provide an early warning for soil pollution. However, because many indices are involved in the exposure-induced oxidative stress response, practical applications of these indices are quite inconvenient. Therefore, it is appropriate to investigate the key monitoring index for use in early warning and pollution monitoring. Using Eisenia fetida as an experimental model in an indoor simulation experiment, the mathematical modelling of the effect on oxidative stress in earthworms under cadmium (Cd) stress was studied. The test lasted 40 d, with the removal of one earthworm every 10 d. The Cd2+ concentration gradient was set as 0, 1, 10, 20, 100, 200, 400, and 800 mg kg-1 dry weight. The earthworms were divided into two sections from the clitellum for the determination of total protein (TP) and peroxidase (POD), superoxide dismutase (SOD), glutathione-S-transferase (GST), glutathione peroxidase (GPX), catalase (CAT), malondialdehyde (MDA), and acetylcholinesterase (AChE) activities. Results showed that POD was the key index of oxidative stress in head tissues after 10 d of exposure, TP was the key index at 20 d, and POD became the key index again at 30 and 40 d. By contrast, in tail tissues, MDA and SOD were the key indices at an exposure time of 10 d, GPX at 20 d, CAT and TP at 30 d, and POD and MDA at 40 d. These results contribute to establishing a scientific method for ecotoxicological diagnosis and revealing the mechanism of soil Cd toxicity.

Effects of tetracycline on the relationship between the microbial community and oxidative stress in earthworms based on canonical correlation analysis

In this study, Eisenia fetida was taken as the test organism and tetracycline was taken as the stress compound. The artificial soil test was conducted to study the utilization intensity of different carbon sources (the Biolog-microplate supplied) by microorganisms under different stress times and stress concentrations. The changes in the in vivo key enzymes activities of earthworms and oxidative stress indicators, such as malondialdehyde (MDA), were explored. The canonical correlation analysis method was the first used to establish a analysis-model to explore the relationship between the functional diversity of microbial community and the oxidative stress in earthworms in vivo under different stress times and concentrations. Research shows: 1) after tetracycline stress, in the earthworm, the CAT, POD, SOD, GPX were related to the microbes that use carbohydrate carbon sources; the GST and AChE were related to the microbes that use polymer carbon sources; the MDA was related to the microbes that use carbon sources: amino acid, carboxylic acid and phenolic acid. 2) Under low concentrations of tetracycline stress, there was no significant relationship between the functional diversity of the microbial communities and the effects of oxidative stress at this concentration. The high concentration of tetracycline can be utilized to screen probiotics that alleviate the effects of oxidative stress. 3) The utilization of carbon sources by microbial community in the earthworm after stress can be used as biomarker of ecotoxicology. It provides a basic theoretical for adding beneficial carbon sources to combat oxidative damage in vivo.

Biochemical responses and DNA damage induced by herbicide QYR301 in earthworm (Eisenia fetida).

QYR301, a novel herbicidal inhibitor of 4-hydroxyphenylpyruvate dioxygenase (HPPD), has great potential for resistant weed control in paddy fields, but massive use of pesticides may result in toxicity to soil non-target organisms. Thus, this study was designed to assess subchronic toxicity of different doses of QYR301 in artificial soil (0, 0.1, 1.0, 2.5, and 5.0mgkg-1) to earthworms (Eisenia fetida) on days 7, 14, 21, and 28 after exposure, using biomarkers of reactive oxygen species (ROS) and malondialdehyde (MDA) contents, activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD) and glutathione-S-transferase (GST), and DNA damage. The ROS content significantly increased for all treatments on 7 and 14 days then decreased, and recovered to control level for 0.1 and 1.0mgkg-1 treatment on day 28. Concerning enzymes activities, QYR301 increased POD, SOD, and GST activities, but inhibited CAT activity. Except for POD activity, SOD, CAT, and GST activities of 0.1mgkg-1 group recovered to control level on day 28. Also, the MDA content of 0.1mgkg-1 group reached control level on day 28. However, DNA damage was observed for all treatments throughout the experiment and it increased with increasing doses and time except for 5.0mgkg-1 treatment on day 28. These results suggested that QYR301 induced excessive ROS production leading to oxidative stress in earthworms, which caused lipid membrane peroxidation and DNA damage ultimately. The findings could provide a theoretical foundation for assessing ecological damage of QYR301 to soils and a guide for future QYR301 applications.

Correlation of the oxidative stress indices and Cd exposure using a mathematical model in the earthworm, Eisenia fetida

With the increase in heavy metal pollution, it is of great significance to evaluate the ecological security and early warning of cadmium (Cd) contaminated soil. In this paper, a mathematical model was established for the first time by combining the advantages of the factor analysis method and the analytic hierarchy process, and was used to screen and analyze the ecological indices of oxidative stress in earthworms under Cd exposure. The experiment lasted for 40 days, removing one earthworm every 10 days. The Cd2+ concentration gradient was set at 0, 1, 10, 20, 100, 200, 400 and 800 mg kg−1. The ecological indices measured were total protein (TP), peroxidase (POD), superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione-S-transferase (GST), catalase (CAT), acetylcholinesterase (AChE) and malondialdehyde (MDA) levels. The results showed that when the earthworm was exposed to Cd2+ for 10 days and 30 days, in the head tissues, the key indices to focus on for monitoring were both POD. At 20 days and 40 days, the key indices were both TP. For the tail tissue tests, under Cd exposure for 10 days, the key indicator focused on for monitoring was MDA. After 20 days of exposure, the key monitoring indicator was AChE. At 30 days, it was CAT, and at 40 days, it was TP. This study provides a theoretical basis for the prompt, inexpensive, accurate and scientific early warning of metal contaminated soils and establishes a foundation for application of the screening model for other ecological indicators.

Effects of a novel neonicotinoid insecticide cycloxaprid on earthworm, Eisenia fetida.

Cycloxaprid (CYC) is a novel neonicotinoid insecticide with high activity against resistant pests but is safe for mammals. The toxic effects of CYC on earthworms (Eisenia fetida) were studied in this paper. The 14-day exposure results showed that CYC is potentially toxic to earthworms, with a 14d-LC50 of 10.21mg/kg dry soil, and that it induced tissue damage to the epidermis, gut, and neurochord at sublethal doses. During a 21-day exposure, CYC induced oxidative stress in earthworms, and both enzyme activities of catalase (CAT) and superoxide dismutase (SOD) were impacted. In addition, expression of the genes Cat and Sod were down- and upregulated, respectively. The activity of the enzyme acetylcholinesterase (AChE) was increased at day 7 but decreased at day 21 after CYC exposure, while expression of the signal transduction-related genes was significantly regulated. Our study shows for the first time that negative impacts could be induced by CYC on earthworms under both acute and chronic exposure through oxidative stress and gene regulation. The present study provides a database for assessing the environmental risk to non-target organisms resulting from the use of CYC.

Antioxidant defense system responses and DNA damage of earthworms exposed to Perfluorooctane sulfonate (PFOS)

The use of earthworms as a sublethal endpoint has significantly contributed to the ecological risk assessment of contaminated soils. Few studies have focused on the potential toxicity of PFOS to earthworms in the soil. In this work, artificial soils were tested, and contact filter paper studies were used. The results showed that earthworm growth was generally inhibited. The antioxidant activities of the enzymes superoxide dismutase, peroxidase, catalase and glutathione peroxidase were initially activated and then inhibited. Reduced glutathione content was observed, and malondialdehyde content was elevated over the duration of the exposure. These results suggested that PFOS induced oxidative stress in earthworms. In addition, the values of olive tail moment, tail DNA% and tail length using SCGE showed similar frequency distributions and increased with increases in the PFOS concentration. These results suggest that all concentrations of PFOS cause DNA damage.

Hydroxyl radical generation and oxidative stress in earthworms (Eisenia fetida) exposed to decabromodiphenyl ether (BDE-209)

Antioxidant responses induced by decabromodiphenyl ether (BDE-209) in the earthworms (Eisenia fetida) were studied after 7 days of exposure. Electron paramagnetic resonance (EPR) spectra indicated that hydroxyl radicals (•OH) in earthworms were significantly induced by 0.01-10 mg/kg of BDE-209. Malondialdehyde (MDA) and protein carbonyl (PCO) were stimulated at 0.5-10 mg/kg and 1-10 mg/kg, respectively. The reduced glutathione (GSH) was inhibited at 1-10 mg/kg while oxidized glutathione (GSSG) accumulated at 0.5-10 mg/kg. The GSH/GSSG ratio decreased at 0.5-10 mg/kg, and superoxide dismutase (SOD) and glutathione-S-transferase (GST) activities were induced at 0.1-1 and 0.5 mg/kg, respectively and both decreased at 10 mg/kg. Catalase (CAT) activities increased at 1-10 mg/kg. The results showed that severe oxidative stress occurred in E. fetida, and may play an important role in inducing the toxicity of BDE-209 on earthworms.