Olive Tail Moment Research Articles

Evaluation of Genotoxic and Mutagenic Effects of Glyphosate Roundup Original®inDendropsophus minutusPeters, 1872 Tadpoles

The herbicide glyphosate is widely used on Brazilian crops and commonly found in water bodies. Despite its usefulness in controlling pests and increasing agricultural production, improper use of this environmental contaminant might accelerate the decline of species, especially frogs. The aim of this study was to evaluate the genotoxic and mutagenic effects of glyphosate Roundup Original® in tadpoles of Dendropsophus minutus by comet assay and micronucleus test. Fourteen egg masses were collected in two permanent ponds in Chapada dos Veadeiros National Park in Alto Paraiso de Goias, Brazil. Acute exposure was conducted with 180 tadpoles maintained for 99 d in a storage tank until developmental stages 26–31. During acclimation, tadpoles were distributed among 36 tanks and exposed to the following concentrations of the active ingredient (ai) glyphosate Roundup Original®: 0.28 mg ai/L, 1.0 mg ai/L, 2.0 mg ai/L, 4.0 mg ai/L of, negative control (0 mg ai/L), and positive control (10 mg ai/L mitomycin C). After 96 h of exposure, the tadpoles were euthanized with 5% benzocaine and submitted to comet assay and micronucleus test. In the comet assay, a significant increase in DNA damage was observed in response to the 0.28 mg ai/L concentration for tail length, % DNA in the tail, and Olive tail moment. There was no dose-response effect at other concentrations. For the micronucleus test, we did not find a statistically significant increase in micronuclei in erythrocytes of D. minutus after 96 h of exposure to glyphosate. Therefore, in the present study we found that tadpoles of D. minutus are extremely sensitive to low concentrations of glyphosate, demonstrating the importance of amphibian tadpoles in studies of genotoxicity and mutagenicity.

Ecotoxicological effects of fertilizers made from pulping waste liquor on earthworm Eisenia fetida

In recent years, increasing efforts have focused on production of organic-inorganic compound fertilizers using ammonium sulfite pulping waste liquor. However, their ecological effects on soil have not been studied. In this study, earthworm Eisenia fetida was exposed to various doses (0, 0.13, 0.26 and 0.52 kg/m2) for different time (7, 14, 21, and 28 d) to evaluate the effects of fertilizers made from pulping waste liquor, including reactive oxygen species (ROS) generation, antioxidant enzymes activities, glutathione S-transferase enzyme (GST) activity, malondialdehyde (MDA) content and DNA damage. Results showed that there were significant increase of ROS and MDA levels after 14 d, inducing production of antioxidant enzymes (superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT)) as well as GST. Before 14 d, excess ROS and MDA caused damage to the DNA of earthworms, leading to gradual increase of Olive tail moment (OTM) in the comet assay. With the exposure time extended to 28 d, owing to the combined effects of elimination of free radicals by antioxidant enzymes and detoxification enzymes as well as self-repairing function of cells, ROS and MDA levels declined slightly and OTM gradually decreased. In summary, this study indicated that there was a toxicological effect on earthworms when fertilizers made from pulping waste liquor were applied to soil, which needs more attention.

Genetic and physiological effects of the natural radioactive gas radon on the epiphytic plant Tillandsia brachycaulos

Radon (222Rn) is the most abundant natural radioactive gas in nature and triggers carcinogenesis. Few reports exist on whether radon can damage plants as it does animals. Therefore, we chose Tillandsia brachycaulos, a common indicator plant, as the material to detect the physiological and genetic changes caused by radon. With an increase in radon concentration, DNA indices (tail length, tail DNA, tail moment and Olive tail moment) from the comet assay and malondialdehyde (MDA) content increased significantly, suggesting that T. brachycaulos inevitably suffered from radiation damage. However, neither the leaf relative conductivity nor the soluble protein content changed significantly with radon fumigation, and no dose-dependent effect existed between the chlorophyll content and radon concentration, indicating that T. brachycaulos had resistance to radon stress. Foliar trichomes most likely excluded the pollutant from plants because DNA damage in T. brachycaulos with trichomes manually removed was considerably greater than that with trichomes. Moreover, the antioxidant enzyme system further reduced the damage of radon to plants because the activity of superoxide dismutase (SOD) increased significantly with the radon concentration.

Molluscicidal impacts of Anagallis arvensis aqueous extract on biological, hormonal, histological and molecular aspects of Biomphalaria alexandrina snails

Controlling of Biomphalaria alexandrina snails by plant molluscicides is the cornerstone in treating schistosomiasis in Egypt. The objective of this study is, to evaluate the molluscicidal activity of the aqueous leaves extract of Anagallis arvensis against B. alexandrina snails. The present results showed that this aqueous extract was lethal for B. alexandrina snails at (LC50 37.9 mg/l; LC90 48.3 mg/l), and caused reduction in survival; reproductive rates and hormonal activity (testosterone (T) and 17β-estradiol (E)) of these snails. Histopathological changes occurred in the hermaphrodite glands of snails exposed to the sub lethal concentrations of this aqueous extract are detected, where, there were degeneration in both eggs and sperms and there were losses of connective tissues between acini. The present investigation revealed that this plant had a genotoxic effect especially with its concentration (LC10 and LC25), where, the length of olive tail moment was significantly increased than control group. These observations prove the potent molluscicidal activity of aqueous leaves extract of A. arvensis against the intermediate hosts of Schistosoma mansoni and provide natural biodegradable resources for snails' molluscicidal agents.

A Comet Assay for DNA Damage and Repair After Exposure to Carbon-Ion Beams or X-rays in Saccharomyces Cerevisiae.

Ionizing radiation (IR) can result in serious genomic instability and genotoxicity by causing DNA damage. Carbon ion (CI) beams and X-rays are typical IRs and possess high-linear energy transfer (LET) and low-LET, respectively. In this article, a comet assay that was optimized by decreasing the electrophoresis time (8 minutes) and voltage (0.5 V/cm) was performed to elucidate and quantify the DNA damage induced by CI or X-rays radiation. Two quantitative methods for the comet assay, namely, comet score and olive tail moment, were compared, and the appropriate means and parameter values were selected for the present assay. The dose–effect relationship for CI or X-rays radiation and the DNA repair process were studied in yeast cells. These results showed that the quadratic function fitted the dose–effect relationship after CI or X-rays exposure, and the trend for the models fitted the dose–effect curves for various repair times was precisely described by the cubic function. A kinetics model was also creatively used to describe the process of DNA repair, and equations were calculated within repairable ranges that could be used to roughly evaluate the process and time necessary for DNA repair.

Evaluation of acetamiprid-induced genotoxic and oxidative responses in Eisenia fetida

As a novel neonicotinoids insecticide, acetamiprid has been widely used worldwide. In this study, a laboratory test was conducted to expose earthworms (Eisenia fetida) to artificial soil spiked with various concentrations of acetamiprid (0, 0.05, 0.10, 0.25 and 0.50 mg/kg of soil) respectively after 7, 14, 21 and 28 d. Reactive oxygen species (ROS) generation, antioxidant enzymes activity including superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferases (GST), malondialdehyde (MDA) content, and DNA damage were determined in earthworms. The ROS level increased in varying degrees at most exposure concentrations. The SOD activity was not significantly affected. The CAT activity was increased in the beginning, then gradually suppressed and resumed to the control level at the end, with the maximum change (171%) occurred at 14 d for 0.05 mg/kg. The GST activity was induced at 7 d, and then inhibited, with the maximum change (67.6%) occurred at 14 d for 0.50 mg/kg. The MDA content had a tendency that increasing at the first and decreasing at the end. The olive tail moment (OTM) in comet assay reflected a dose-dependent relationship, and DNA damage initially increased and then decreased over time. The results suggest that the sub-chronic exposure of acetamiprid can cause oxidative stress and DNA damage of earthworm and change the activity of the anti-oxidant enzyme. In addition, ROS content and DNA damage can be good indicators for assessing environmental risks of acetamiprid in earthworms.

Elevated oxidative DNA damage in patients with coronary artery disease and its association with oxidative stress biomarkers

Objective: The objective of the present study was to evaluate oxidative DNA damage in peripheral blood leukocytes (PBLs) of patients with coronary artery disease (CAD) and to explore the relationship of oxidised purine and pyrimidine with oxidative stress.Methods: The study participants (n = 100) included 50 patients and unrelated 50 age-, sex- and population-subgroup (Jat Sikhs)-matched healthy controls. Oxidative DNA damage using the modified enzymatic comet in PBLs, and malondialdehyde (MDA) levels, total oxidant status (TOS) and total antioxidant status (TAS) in blood serum samples using spectrophotometric methods was determined.Results: The basal DNA damage of percent tail DNA (T-DNA%) was increased as were tail moment (TM) and olive tail moment (OTM). Oxidative DNA damage in terms of oxidised purines and oxidised pyrimidines was also significantly (p < .001) elevated in patients. Rather the advanced stages of CAD, unstable angina and acute myocardial infarction had significantly more basal and oxidative DNA damage (p < .05) compared to stable angina. MDA levels (p < .01) and TOS (p < .001) were increased significantly in patients with significant (p < .001) decrease in TAS. There was positive correlation of oxidised purines (T-DNA% r = 0.399, p = .004; TM r = 0.623, p = .001; OTM r = 0.456, p= .001) and of total oxidative damage (TM r = 0.515, p = .001; OTM r = 0.463, p = .001) with disease severity, and, with TOS (r = 0.279, p = .050) and negative with TAS (r = −0.341, p = .015). Multiple linear regression analysis revealed TOS and disease severity as independent predictors of oxidative DNA damage.Conclusions: There was significant increase in oxidative DNA damage and oxidative stress in CAD patients compared to levels in healthy controls.

Role of p38 MAPK in disease relapse and therapeutic resistance by maintenance of cancer stem cells in head and neck squamous cell carcinoma.

This study aimed to investigate the role of p38 MAPK in maintenance of cancer stem cell (CSC) phenotype, therapy resistance, and DNA damage repair and response in head and neck squamous cell carcinoma (HNSCC). In this study, 104 HNSCC patients were included. Western blot, immunohistochemistry, and qPCR analysis were performed to investigate the expression level of p-p38 and CSC markers in cut margin and tumor area of HNSCC patients. The expression level of p-p38 and CSC markers was also evaluated in HNSCC cells with or without p38 inhibitor. Chemoresistance, wound healing capacity, and multicellular tumor spheroids (MCTS) formation capacity were evaluated in HNSCC-derived cell lines with or without p38 inhibitor. In addition, DNA damage response and repair capacities were also evaluated in HNSCC cells after p38 inhibition using alkaline comet assay and γ-H2 AX immunostaining. We observed that recurrence could be associated with upregulated status of p-p38 and p38α gene in cut margin area of HNSCC patients as compared to tumor region. p38-inhibited cells showed significantly reduced expression of CSC markers, chemosensitivity toward cisplatin, reduced migration potential, and sphere-forming ability along with increased apoptotic population after treatment with increasing concentration of cisplatin. p38-inhibited cells also exhibited significantly increased comet olive tail moment and accumulation of γ-H2 AX, demonstrating increased DNA damage. This study demonstrated that p38 MAPK activation may play a role in therapeutic resistance and disease relapse in HNSCC by maintenance of CSCs phenotype.

Protective effects of folic acid on DNA damage and DNA methylation levels induced by N-methyl-N'-nitro-N-nitrosoguanidine in Kazakh esophageal epithelial cells.

The protective effects of folic acid on DNA damage and DNA methylation induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in Kazakh esophageal epithelial cells were investigated using a 3 × 3 factorial design trial. The cells were cultured in vitro and exposed to media containing different concentrations of folic acid and MNNG, after which growth indices were detected. DNA damage levels were measured using comet assays, and genome-wide DNA methylation levels (MLs) were measured using high-performance liquid chromatography. The DNA methylation of methylenetetrahydrofolate reductase (MTHFR) and folate receptor-α (FRα) genes was detected by bisulfite sequencing polymerase chain reaction (PCR). The results showed significant increases in tail DNA concentration, tail length, and Olive tail moment (p < 0.01); a significant reduction of genome-wide DNA MLs (p < 0.01); and an increase in the methylation frequencies of MTHFR and FRα genes. In particular, significant differences were observed in the promoter regions of both genes (p < 0.01). Our study indicated that a reduction in folic acid concentration promotes DNA damage and DNA methylation in Kazakh esophageal epithelial cells upon MNNG exposure. Thus, sufficient folic acid levels could play a protective role against the damage induced by this compound.

Toxic effect of [Omim]BF4 and [Omim]Br on antioxidant stress and oxidative damage in earthworms (Eisenia fetida)

In this paper, model soil organism, earthworms (Eisenia fetida), were selected to examine the chronic toxic effect of two different ionic liquids (ILs) [Omim]BF4 and [Omim]Br. Earthworms were put into different ILs concentrations (0, 5, 10, 20, 40 mg/kg) in artificial soil and random selected on days 7, 14, 21 and 28. Reactive oxygen species (ROS), antioxidant enzymes and detoxifying enzyme glutathione-S-transferase (GST) were researched for determination of antioxidant stress. Malondialdehyde (MDA) and olive tail moment (OTM) were researched to determine the oxidative damage. Both the pollutants had the same effect on earthworms: ILs led to accumulation of ROS, and then antioxidant enzymes and detoxification enzyme all changed to eliminate the effects of ROS, and the above process led to lipid peroxidation and DNA damage in earthworms. This paper shows that [Omim]BF4 and [Omim]Br both caused toxicity to earthworms and had the similar toxicity levels.

InP/ZnS QDs exposure induces developmental toxicity in rare minnow (Gobiocypris rarus) embryos

We investigated the in vivo toxicity of InP/ZnS quantum dots (QDs) in Chinese rare minnow (Gobiocypris rarus) embryos. The 72 h post-fertilization (hpf) LC50 (median lethal concentration) was 1678.007 nmol/L. Rare minnows exposed to InP/ZnS QDs exhibited decreased spontaneous movement, decreased survival and hatchability rates, and an increased malformation rate. Pericardial edema, spinal curvature, bent tails and vitelline cysts were observed. Embryonic Wnt8a and Mstn mRNA levels were significantly up-regulated after InP/ZnS QDs treatment at 48 hpf (200 nmol/L) (p < 0.05). The superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels at 96 hpf (800 nmol/L) had an increasing trend. Hsp70 mRNA expression was significantly changed at 48 hpf (200 nmol/L), but compared with the blank control, the different InP/ZnS QDs treatments did not significantly change the Olive tail moments (p > 0.05). Thus, InP/ZnS QDs caused teratogenic effects and death during the development of Chinese rare minnow embryos, but InP/ZnS QDs did not cause significant genetic toxicity during Chinese rare minnow development.

Combined effect of Benzophenone-2 and ultraviolet radiation promote photogenotoxicity and photocytotoxicity in human keratinocytes

Benzophenone-2 (BP2), a common ingredient of sunscreens formulation is widely used as UV filter. We have assessed the photogenotoxic and photocytotoxic potential of BP2. Photostability test showed that BP2 is unstable under UV exposure. Cell proliferation assay revealed that viability of HaCaT cells significantly reduced under UVA, UVB and sunlight exposure. DCF fluorescence intensity proved intracellular ROS generation capacity of BP2 under sunlight, UVA and UVB irradiation. Photodynamic degradation of guanine base of DNA is promoted by BP2 under UV treatment. Genotoxicity assessed by comet assay, showed that photosensitized BP2 enhanced DNA damage, which is measured in term of % tail DNA and olive tail moment. Genotoxic potential of BP2 was further validated with photomicronuclei assay. Photogenotoxicity of BP2 was lastly confirmed by formation of CPDs (Cyclo butane pyrimidine dimmers). DNA damage induced by BP2 was irreversible and extended incubation periods (6–12 h) not favored the recovery from damaged DNA. JC 1 staining showed significant reduction in mitochondrial membrane potential. Membrane integrity compromisation of HaCaT cells was established by AO (Acridine orange), EtBr (Ethidium bromide) staining and confirmed with sub G1 population of cell cycle. Thus, results suggest that BP2 should be avoided in topical application for safe sunscreen practices.

Exposure to non-ionizing electromagnetic fields emitted from mobile phones induced DNA damage in human ear canal hair follicle cells

ABSTRACTThe aim of this study was to investigate effect of radiofrequency radiation (RFR) emitted from mobile phones on DNA damage in follicle cells of hair in the ear canal. The study was carried out on 56 men (age range: 30–60 years old)in four treatment groups with n = 14 in each group. The groups were defined as follows: people who did not use a mobile phone (Control), people use mobile phones for 0–30 min/day (second group), people use mobile phones for 30–60 min/day (third group) and people use mobile phones for more than 60 min/day (fourth group). Ear canal hair follicle cells taken from the subjects were analyzed by the Comet Assay to determine DNA damages. The Comet Assay parameters measured were head length, tail length, comet length, percentage of head DNA, tail DNA percentage, tail moment, and Olive tail moment. Results of the study showed that DNA damage indicators were higher in the RFR exposure groups than in the control subjects. In addition, DNA damage increased with the daily duration of exposure. In conclusion, RFR emitted from mobile phones has a potential to produce DNA damage in follicle cells of hair in the ear canal. Therefore, mobile phone users have to pay more attention when using wireless phones.

Assessment of neurohepatic DNA damage in male Sprague-Dawley rats exposed to organophosphates and pyrethroid insecticides.

The current work was undertaken to test the genotoxic potential of chlorpyrifos (CPF), dimethoate, and lambda cyhalothrin (LCT) insecticides in rat brain and liver using the single cell gel electrophoresis (comet assay). Three groups of adult male Sprague-Dawley rats were exposed orally to one third LD50of CPF, dimethoate, or LCT for 24 and 48h while the control group received corn oil. Serum samples were collected for estimation of malondialdehyde (MDA) and glutathione peroxidase (GPx); the brain and liver samples were used for comet assay and for histopathological examination. Results showed that signs of neurotoxicity appeared clinically as backward stretching of hind limb and splayed gait in dimethoate and LCT groups, respectively. CPF, LCT, and dimethoate induced oxidative stress indicated by increased MDA and decreased GPx levels. CPF and LCT caused severe DNA damage in the brain and liver at 24 and 48h indicated by increased percentage of DNA in tail, tail length, tail moment, and olive tail moment. Dimethoate induced mild DNA damage in the brain and liver at 48h. Histopathological changes were observed in the cerebrum, cerebellum, and liver of exposed rats. The results concluded that CPF, LCT, and dimethoate insecticides induced oxidative stress and DNA damage associated with histological changes in the brain and liver of exposed rats.

N-Acetyl-tryptophan glucoside (NATG) protects J774A.1 murine macrophages against gamma radiation-induced cell death by modulating oxidative stress

Immune system is amongst the most radiosensitive system to radiation-induced cellular and molecular damage. Present study was focused on the evaluation of radioprotective efficacy of a novel secondary metabolite, N-acetyl tryptophan glucoside (NATG), isolated from a radioresistant bacterium Bacillus sp. INM-1 using murine macrophage J774A.1 cells experimental model. Radioprotective efficacy of NATG against radiation-induced DNA damage and apoptosis was estimated using phosphatidyl-serine-externalization Annexin V-PI and Comet assay analysis. Radiation-induced cell death is the outcome of oxidative stress caused by free radicals. Therefore, perturbations in antioxidant enzymes i.e., superoxide dismutase (SOD), catalase, glutathione-s-transferase (GST) and GSH activities in irradiated and NATG pre-treated irradiated J774A.1 cells were studied. Results of the present study demonstrated that NATG pre-treated (0.25µg/ml) irradiated (20Gy) cells showed significant (p < 0.05) reduction in apoptotic cells index at 4-48h as compared to radiation alone cells. Comet assay exhibited significant protection to radiation-induced DNA damage in J774A.1 cells. Significantly shortened DNA tail length, increased % Head DNA contents and lower olive tail moment was observed in NATG pre-treated irradiated cells as compared to radiation alone cells. Further, significant increase in catalase (~ 3.9 fold), SOD (67.52%), GST (~ 1.9 fold), and GSH (~ 2.5 fold) levels was observed in irradiated cells pre-treated with NATG as compared to radiation-alone cells. In conclusion, current study suggested that NATG pre-treatment to irradiated cells enhanced antioxidant enzymes in cellular milieu that may contribute to reduce oxidative stress and decrease DNA damage which resulted to significant reduction in the cell death of irradiated macrophages.

Genotoxicity and Hemocompatibility of a Novel Calcium Aluminate-Based Cement.

Objective:The aim of this in vitro study was to evaluate the genotoxicity and hemocompatibility of a novel calcium aluminate-based cement, EndoBinder (EB) (Binderware, São Carlos, SP, Brazil) and compare it with Angelus White Mineral Trioxide Aggregate (MTA) (AWMTA) (Angelus, Soluções Odontológicas, Londrina, PR, Brazil).Methods:For evaluation of genotoxicity, a comet assay was performed with Chinese hamster ovary (CHO) cells that had been grown for 24 h in Dulbecco’s Modified Eagle Medium incubated with each of the cements for 24 h at 37°C. DNA percentage in head and Olive tail moment were analyzed. For assessment of hemocompatibility, erythrocyte lysis quantification, and concentration of plasma fibrinogen were determined in human blood samples placed in contact with each of the materials. One way analysis of variance (ANOVA) followed by post hoc Tukey test and Student t-test were used for data analysis of genotoxicity and hemocompatibility, respectively.Results:Results showed that the genotoxic effects of EB and AWMTA were comparable to that of the negative control, with no statistically significant differences between AWMTA and negative control (P>0.05). Compared to AWMTA, EB showed greater hemolytic potential when placed in direct contact with erythrocytes (P<0.05). Fibrinogen values were low for both materials, with protein concentration being greater in samples exposed to EB than to AWMTA.Conclusion:Both materials presented a higher hemolytic behaviour compared to what is established by international standards. Fibrinogen formation was low for both materials, and DNA damage induction was not observed in a comet assay.

WITHDRAWN: Cytogenetics alteration in adult men involved in the recycling of electronic wastes

Abstract In this data article, 146 villagers (exposed group) were randomly selected from the workers who involved in the e-wastes recycling directly as a daily job in Tianjin. Control group, including 121 villagers, came from another town without e-waste disposal sites. Chromosomal aberrations (CA) and cytokinesis blocking micronucleus (CBMN) were performed to detect the cytogenetic effect for each subject. DNA damage was detected using comet assay; the DNA percentage in the comet tail (TDNA%), tail moment (TM), and Olive tail moment (OTM) were recorded to describe DNA damage to lymphocytes and spermatozoa. Routine semen analysis, spermatozoa motility and morphology were analyzed. The RT 2 Profiler PCR array was used to measure levels of expression of 84 genes related to quality of DNA. It showed significant relationships between CA, CBMN, DNA damage and exposure time in exposure subjects. The alteration of sperm motility rate, abnormality rate and total sperm counts had association with exposure time and age.

Preparation of β-CD-Ellagic Acid Microspheres and Their Effects on HepG2 Cell Proliferation.

Objective: In this study, β-cyclodextrin (β-CD) was chosen as the coating for ellagic acid to prepare ellagic acid microspheres, and the effect of microspheres on the growth of HepG2 cells was observed. Methods: Scanning electron microscopy, infrared spectroscopy, and release rate analysis were used to identify the formation of ellagic acid microspheres. Methyl thiazolyl tetrazolium (MTT) assay was used to detect the effect of different concentrations of ellagic acid microspheres on tumor cell proliferation at 6, 12, 24 and 36 h, and cell morphology and quantity were observed using hematoxylin-eosin (HE) staining. Single-cell gel electrophoresis was used to observe the effect of ellagic acid microspheres on the DNA damage of HepG2 cells, and the Olive tail moment and the mRNA expression of tumor suppressor protein gene p53 was measured. Results: β-CD could be used as wrapping material of ellagic acid to prepare ellagic acid microspheres. HepG2 cell proliferation could be inhibited by 0.1, 0.3 and 0.5 g/L of ellagic acid microspheres in a dose- and time-dependent manner, and the mechanism of proliferation inhibition was related to DNA damage and cell apoptosis. Conclusion: Preparing ellagic acid microspheres with β-CD is feasible, and ellagic acid microspheres have potential therapeutic value (anticancer).

Toxicity of arsenite to earthworms and subsequent effects on soil properties

Arsenic (As) is widely distributed in soil and is toxic to plants, animals and humans. In this study, earthworms (Eisenia fetida) were exposed to five concentrations of sodium arsenite (5, 10, 20, 40, and 80 mg As kg−1) in farm soils for 28 d. With increasing soil As(III) concentrations, As bioaccumulation in earthworms increased (maximum bioaccumulation factor 3.77), and levels of reactive oxygen species (ROS) and malondialdehyde (MDA) were elevated. The expression of nuclear factor erythroid 2- related factor 2 (Nrf2) and heme oxygenase -1 (HO-1) were upregulated by As in a dose-dependent pattern, and reached 5.93 and 2.94 times the control values for Nrf2 and HO-1 respectively, at 28 d in the 80 mg As kg−1 soil treatment. Similarly, DNA damage, as measured in earthworm sperm using the comet assay, increased with increasing As(III) concentrations, with ‘Olive tail moment’ values in the comet assay ranging from c. 0.5 in Control to c. 3.5 at 80 mg As kg−1 soil. In contrast, activity of the antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), decreased. These results indicate that As(III) caused oxidative stress that resulted in damage to lipids and DNA. Nrf2 and HO-1 protein expression was demonstrated in earthworms for the first time to our knowledge, and found to be a sensitive biomarker of arsenic contamination. The presence of earthworms was also found to change the distribution of As in soil, in particular, reducing the proportion in the residual fraction and increasing the proportion in As bound to Fe-oxides. This may result in increased bioavailability of bound arsenic. Soil organic matter, NH4+-N, NO3−-N and available K were indirectly changed by the As(III) through its toxicity to earthworms. This study helps to inform future assessments and biomonitoring of soil arsenic contamination.

Oxidative stress, cell cycle arrest, DNA damage and apoptosis in adult zebrafish (Danio rerio) induced by tris(1,3-dichloro-2-propyl) phosphate

Tris(1,3-dichloro-2-propyl)phosphate (TDCPP) is an additive flame retardant of high production volume, and frequently detected in biota and environment. However, knowledge on its potential risk and toxicological mechanism still remains limited. In this study, DNA damage, transcriptomic responses and biochemical changes in the liver of zebrafish (Danio rerio) induced by TDCPP were investigated. Zebrafish was exposed to 45.81μg/L (1/100 (96h-LC50)) and 229.05μg/L (1/20 (96h-LC50)) TDCPP for 7 d. The reactive oxygen species (ROS) and GSH contents, in addition to antioxidant enzyme activities in the liver changed significantly, and the mRNA levels of genes related to oxidative stress were alerted in a dose-dependent and/or sex-dependent manner after exposure to TDCPP. Significant DNA damage in zebrafish liver was found, and olive tail moment increased in a concentration-dependent manner. Moreover, exposure of TDCPP at 45.81μg/L level activated the cell cycle arrest, DNA repair system and apoptosis pathway in male zebrafish, and 229.05μg/L TDCPP exposure inhibited those pathways in both male and female zebrafish. The cell apoptosis was confirmed in TUNEL assay as higher incidence of TUNEL-positive cells were observed in zebrafish exposed to 229.05μg/L TDCPP. Our results also indicated that males were more sensitive to TDCPP exposure compared with females. Taken together, our results showed that TDCPP could induce oxidative stress, cell cycle arrest, DNA damage and apoptosis in adult zebrafish liver in sex- and concentration-dependent manners.