Impacts of sewage sludges deposition on agricultural soils: Effects upon model soil organisms.

During years sewage sludges have been worldwide poured in agricultural soils to enhance vegetal production. The "Landfill 17" located in Gernika-Lumo town (43°19'28.9"N 2°40'30.9"W) received for decades sewage sludges from the local Waste Water Treatment Plant (WWTP) with agricultural purposes. To this WWTP, several pollutants as heavy metals (Cd, Cr, Ni, Pb), PAHs (benzo(a)pyrene among many others) and pesticides (i.e. dieldrin) could have arrived from local industry and be widespread all over the landfill. Soil invertebrates like earthworms and plants are of special interest due to their close contact with the polluted matrix and their potential effects by the presence of pollutants. In this context, the aim of the present work was to determine the health status of landfill soils by evaluating the effects on model soil organisms exerted by long-lasted pollutants after on site deposition of WWTP active sludges. With such a purpose, different standard toxicity tests and cellular level endpoints were performed on lettuce and earthworms. Indeed, germination (EPA 850.4100) and root elongation (EPA 850.4230) tests were carried out in Lactuca sativa, while OECD acute toxicity test (OECD-204), reproduction test (OECD-222) and Calcein-AM viability test with coelomocytes were applied in Eisenia fetida worms. For the exposure, soils collected in the landfield containing low, medium and high concentrations of pollutants were selected, and as reference LUFA 2.3 natural standard soil was chosen. While no differences were shown in the assays with L. sativa, significant differences between sludge exposed groups and control group were recorded with E. fetida, with lower coelomocyte number and viability and higher tissue metal accumulation after 28 days of exposure to polluted soils. These results confirmed the impact of contaminants to soil biota even after long periods of time.

Synthesis, Antibacterial and Anthelmintic Activity of Novel 3-(3-Pyridyl)-oxazolidinone-5-methyl Ester Derivatives.

In this study, a series of 3-(3-pyridyl)-oxazolidone-5-methyl ester derivatives was synthesized and characterized by 1H NMR, 13C NMR, and LC-MS. The conducted screening antibacterial studies of the new 3-(3-pyridyl)-oxazolidone-5-methyl ester derivatives established that the methyl sulfonic acid esters have broad activity spectrum towards Staphylococcus aureus, Streptococcus pneumoniae, Bacillus subtilis and Staphylococcus epidermidis. Among them, compound 12e has the most potent activity, with an MIC of 16 µg/mL against B.subtilis, and could reduce the instantaneous growth rate of bacteria. Furthermore, molecular docking studies were also simulated for compound 12e to predict the specific binding mode of this compound. In addition, anthelmintic activity of these compounds was also evaluated against adult Indian earthworms (Pheretima posthuman). The results showed that compound 11b had the best effect. These results above can provide experimental reference for the development of novel antibacterial and anthelmintic drugs.

Ecotoxicological Effects of Aflatoxins on Earthworms under Different Temperature and Moisture Conditions.

Aflatoxin contamination remains one of the most important threats to food safety and human health. Aflatoxins are mainly found in soil, decaying plant material and food storage systems and are particularly abundant during drought stress. Regulations suggest the disposal of aflatoxin-contaminated crops by incorporation into the soil for natural degradation. However, the fate and consequences of aflatoxin in soil and on soil organisms providing essential ecological services remain unclear and could potentially pose a risk to soil health and productivity. The protection of soil biodiversity and ecosystem services are essential for the success of the declared United Nations Decade on Ecosystem Restoration. The focus of this study was to investigate the toxicological consequences of aflatoxins to earthworms' survival, growth, reproduction and genotoxicity under different temperature and moisture conditions. Results indicated an insignificant effect of aflatoxin concentrations between 10 and 100 µg/kg on the survival, growth and reproduction but indicated a concentration-dependent increase in DNA damage at standard testing conditions. However, the interaction of the toxin with different environmental conditions, particularly low moisture, resulted in significantly reduced reproduction rates and increased DNA damage in earthworms.

Ecotoxicity of herbicide carfentrazone-ethyl towards earthworm Eisenia fetida in soil.

Herbicides pose a potential threat to the soil biodiversity and health. Carfentrazone-ethyl (CE), a triazolinones herbicide, is increasingly used in agricultural production. Its non-target toxic effects on soil microorganisms and soil enzymes are reported recently. However, the sublethal toxicity of CE on soil invertebrates like earthworms is not yet known. Therefore, in this work, the sublethal toxic effects of CE (0.05, 0.5, and 5.0 µg/g in soil) on the soil earthworm (Eisenia fetida) were evaluated using a battery of biomarkers including reactive oxygen species (ROS), enzyme (superoxide dismutase-SOD, catalase-CAT, peroxidase-POD, and glutathione S-transferase-GST) activities, malondialdehyde (MDA) contents, histopathological and DNA damage. Results indicated that CE increased ROS contents, enzyme activities, and MDA contents in the short-time (14 d), thus, causing a slight oxidative stress to E. fetida. However, the toxic effects of CE on earthworms gradually disappeared after 14 days. The CE did not cause histopathological and DNA damage in earthworms. Integrated Biological Response index (IBR) indicated that both concentration and exposure time of CE regulated its sublethal toxicity on earthworms. In conclusion, herbicide CE is safe to soil invertebrate earthworms when applied at the recommended doses. Our results contribute to the current understanding of CE effects on soil earthworms, and can be useful in developing soil health strategies under agrochemical use.

Ecotoxicity of chlorpyrifos on earthworm Eisenia fetida (Savigny, 1826): Modifications in oxidative biomarkers.

Chlorpyrifos (CPF; O, O'-diethyl-3, 5, 6-trichloro-2-pyridyl phosphorothionate) as an organophosphate compound with moderate toxicity that entered the soil in 1965, is widely used as an active substance of many insecticides. CPF may affect some biochemical mechanisms, particularly through disrupting pro- and anti-oxidant balance and inducing free radical-induced oxidative stress. Expired pesticides, if present in ecosystem, may pose new issues of toxicological concern. In the current study, modifications in the oxidative stress (OS) hallmarks including the content of lipid peroxidation (LPO/MDA) and the activities of antioxidant enzymes catalase (CAT) and glutathione S-transferase (GST) in the whole body extract and total antioxidant capacity (TAC), in the coelomic fluid (CF) of earthworm Eisenia fetida were evaluated spectrophotometrically after exposure to different concentrations (1/20th, 1/10th, and 1/5th of LC50) of fresh and expired CPF for 4 and 8 days. First, LC50 for both fresh and expired CPF were determined by using probit method as ≤192 and ≤ 209 mg/kg dry soil, respectively. Our results also revealed that both fresh and expired CPF could be toxic to earthworms via inducing OS at higher concentrations. Here, CPF-induced OS was determined by a significant elevation (p < 0.05) in LPO content, CAT and GST activities and also a meaningful decrease (p < 0.05) in TAC value. Briefly, CPF may exhibit toxic effects in earthworms in the fresh and expired forms via changing oxidative balance and modifying some biochemical markers in the whole body. Further unraveling is needed to elucidate CPF-related impairments in soil organisms.

Evaluation of the combined toxicity of multi-walled carbon nanotubes and cadmium on earthworms in soil using multi-level biomarkers.

The coexistence of multi-walled carbon nanotubes (MWCNTs) with cadmium (Cd) in soil may cause the combined biological effects, but few study reported about their joint toxic effects on earthworms. Therefore, this study investigated the effects of sub-lethal levels of MWCNTs (10, 50, 100 mg/kg) and Cd (2.0, 10 mg/kg) on earthworms Eisenia fetida for 14 days. The changes in multi-level biomarkers of growth inhibition rate, cytochrome P450 isoenzymes (CYP1A2, 2C9 and 3A4), and small molecular metabolites (metabolomics) were determined. The toxic interaction between MWCNTs and Cd was characterized by the combination of the biomarker integration index (BRI), joint effect index concentration addition index (CAI), and the effect concentration addition index (EAI). The results showed that the single MWCNTs exposure caused insignificant change in most biomarkers, while the combined exposure of MWCNTs (50-100 mg/kg) and 10 mg/kg Cd led to significant changes in ten most important metabolites identified by metabolomics and activities of CYP1A2, 2C9, and 3A4. Compared with the toxicity of Cd alone, the combined toxicity of the mixture was significantly reduced. According to the integration of BRI and CAI/EAI, a clearly antagonistic interaction at relatively low effects was observed between MWCNTs and Cd. The responses of multiple biomarkers suggest the toxic action mode of the mixture on earthworms was related to the oxidative injury, and the disruption of amino acid, purine, and pyrimidine metabolism, and the urea cycle.

Bisphenol A affects the pulse rate of Lumbriculus variegatus via an estrogenic mechanism.

Invertebrates are recognized as important species in endocrine disrupting chemical (EDC) testing. However, it is poorly understood whether the effects of EDCs in invertebrates are mediated by hormonal mechanisms. Previously, we showed that bisphenol A (BPA) affected the physiology of the freshwater oligochaete Lumbriculus variegatus. In the present study, we examined the mechanism of the impact of BPA on L. variegatus, using pulse rate of the dorsal blood vessel (DBV) as an endpoint. Both long term and acute exposures to BPA increased the pulsing rate of DBV. The former had a distinct inverted-U dose response relationship with a most efficacious dose of 10-9 M, which increased the pulse rate from 8.97 to 10.9 beats/min. The effects of BPA were mimicked by the synthetic estrogen ethinylestradiol with a most efficacious dose of 10-12 M. Interestingly E2 had no effect on pulsing rate, either acute or long term. The sensitivity of L. variegatus to estrogens were exquisite, with detectable effects at 10-14 to 10-10 M range. Both the long term and acute effects of BPA were partially or fully blocked by various vertebrate estrogen receptor (ER) antagonists, including ICI 182,780, MPP and G15. Our results suggest that the impact of BPA on pulsing rate of L. variegatus is likely mediated by an estrogenic mechanism instead of general toxicity. The exceptionally high sensitivity of L. variegatus to some estrogens makes it a possible tool for estrogenic EDC screening.

Soil invertebrate toxicity and bioaccumulation of nano copper oxide and copper sulphate in soils, with and without biosolids amendment.

The fate, toxicity and bioaccumulation of copper oxide nanoparticles (nCuO) was investigated in soil, with and without biosolids amendment, through chronic exposures using the earthworm, Eisenia andrei, and the collembolan, Folsomia candida. The effects of copper sulphate (CuSO4) were included so as to compare the behavior of nCuO to a readily soluble counterpart. The fate of nCuO was evaluated through characterization of dissolved and nano-particulate fractions (via single particle ICP-MS) as well as extractable Cu2+ throughout the duration of select tests. Neither Cu form was particularly toxic to F. candida, but effects on E. andrei reproduction were significant in all treatments (IC50 range: 98 - 149 mg Cu kg-1 dry soil). There were no significant differences in toxicity between the Cu forms, nor in extractable Cu2+ activities, indicative that particle dissolution within the soil and, subsequent activity of Cu2+ was likely the primary mode of toxicity in the nCuO exposures. The presence of biosolids did not significantly alter toxicity of nCuO, but did affect Cu2+ activity over time. Bioaccumulation of total Cu in E. andrei when exposed to nCuO (kinetic bioaccumulation factor (BAFk): 0.80 with biosolids and 0.81 without) was lower than exposure to CuSO4 (BAFk: 2.31 with biosolids and 1.12 without). Enhanced dark-field hyperspectral imaging showed accumulation of nCuO along the epidermis and gut of E. andrei, with trace amounts observed in muscle and chloragogenous tissue, providing evidence of nCuO translocation within the organism. The present study demonstrates that the current risk assessment approach for trace metals in the environment, based on substance solubility and bioavailability of the dissolved free ion, are applicable for nCuO exposure to soil invertebrates, but that the rate of particle dissolution in different soil environments is an important factor for consideration.

Effect of chlorpyrifos on the earthworm Eudrilus euginae and their gut microbiome by toxicological and metagenomic analysis.

The earthworms are important soil invertebrates and play a crucial role in pedogenesis. The application of pesticides and prolonged exposure to pesticides causes mortality of earthworms apart from profoundly affecting the resident gut microbiome. The microbiome plays a significant effect on the metabolic processes associated with earthworms. The pesticide Chlorpyrifos (CPF) was studied for its toxicity on Eudrilus euginae by toxicity studies. The LC50 value of filter paper contact test and acute toxicity test was 3.8 mg/mL and 180 mg/kg. The prolonged exposure of earthworms to pesticide on reproductive toxicity resulted in the mortality of earthworms and absence of cocoon formation. Further, the effects of CPF on the whole gut microbiome of E. euginae was analyzed using a long amplicon Nanopore sequencing. Results indicated no fluctuations with Firmicutes and Bacteroidetes, that were found to be dominant at bacterial phyla level while at the genus level, remarkable differences were noticed. Clostridium dominated the earthworm gut prior to CPF exposure while Bacillus dominated after exposure. Similarly, the fungal members such as Ascomycota and Basidiomycota were observed to dominate the gut of earthworm at the phyla level before and after exposure to CPF. In contrast, Clavispora (65%) was the dominant genus before CPF exposure and Taloromyces (42%) dominated after the CPF exposure. Our study demonstrates the effect of CPF on the mortality of E. euginae while the amplicon sequencing established the unique microbiome of the gut in response to the CPF exposure.

Assessing potential indicator of endocrine-disrupting property of chemicals using soil invertebrates.

Vitellogenin has been regarded as an acceptable indicator for evaluating the endocrine-disrupting property of chemicals using fish. However, the endocrine-disrupting property of chemicals has been rarely evaluated using soil species. This study aimed to find evidence that endocrine-disrupting chemicals (including the natural hormones estradiol and dihydrotestosterone) can affect the reproductive organs of earthworms. Earthworms were exposed to 17ß-estradiol, dihydrotestosterone, bisphenol A, and methylparaben for seven days. The four EDCs inhibited normal oogenesis and maturation of oocytes in earthworm ovary, and dihydrotestosterone and bisphenol A were observed to damage earthworm seminal vesicle tissues and inhibit normal spermatogenesis. The evidence showed that the tested EDCs have an adverse effect on female and male reproductive systems of soil invertebrates. The results suggest that the evaluations of oogenesis and spermatogenesis in the ovary and seminal vesicles of earthworms are useful indicators for investigating the endocrine-disrupting property of chemicals. Additionally, our results encourage further studies on developing novel indicators using soil invertebrates to evaluate the effects of the toxicity of endocrine-disrupting chemicals on the soil ecosystem.

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.

Acute toxicity and sublethal effects of sodium laureth sulfate on oxidative stress enzymes in benthic oligochaete worm, Tubifex tubifex.

The present study was performed to determine the acute toxicity of sodium laureth sulfate (SLES) and its sublethal effects on oxidative stress enzymes in benthic oligochaete worm Tubifex tubifex. The results showed that 96 h median lethal concentration (LC50) value of SLES for Tubifex tubifex is 21.68 mg/l. Moreover exposed worms showed abnormal behaviours including incremented erratic movement, mucus secretion, and decreased clumping tendency at acute level. Percentage of autotomy additionally increased significantly (P < 0.05) with the increasing dose of toxicant at 96 h exposure. Sublethal concentrations of SLES (10% and 30% of 96 h LC50 value) caused paramount alterations in the oxidative stress enzymes. Superoxide dismutase (SOD), reduced glutathione (GSH), glutathione S-transferase (GST), and glutathione peroxidase (GPx) exhibited a striking initiatory increment followed by a resulting descending pattern. Moreover, during exposure times, catalase (CAT) activity and malondialdehyde (MDA) level increased markedly with incrementing concentrations of SLES. However, the effects of sodium laureth sulfate on Tubifex tubifex were characterized and portrayed by the development of a correlation matrix and an integrated biomarker response (IBR) assessment. These results indicate that exposure to this anionic surfactant alters the survivability and behavioral response at acute level and modifies changes in oxidative stress enzymes at sublethal level in Tubifex tubifex.

Toxic mechanism of pyrene to catalase and protective effects of vitamin C: Studies at the molecular and cell levels.

Polycyclic aromatic hydrocarbons, distributing extensively in the soil, would potentially threaten the soil organisms (Eisenia fetida) by triggering oxidative stress. As a ubiquitous antioxidant enzyme, catalase can protect organisms from oxidative damage. To reveal the potential impact of polycyclic aromatic hydrocarbon pyrene (Pyr) on catalase (CAT) and the possible protective effect of Ascorbic acid (vitamin C), multi-spectral and molecular docking techniques were used to investigate the influence of structure and function of catalase by pyrene. Fluorescence and circular dichroism analysis showed that pyrene would induce the microenvironmental changes of CAT amino acid residues and increase the α-helix in the secondary structure. Molecular simulation results indicated that the main binding force of pyrene around the active center of CAT is hydrogen bonding force. Furthermore, pyrene inhibited catalase activity to 69.9% compared with the blank group, but the degree of inhibition was significantly weakened after vitamin C added into the research group. Cell level experiments showed that pyrene can increase the level of ROS in the body cavity cell of earthworms, and put the cells under the threat of potential oxidative damage. Antioxidants-vitamin C has a protective effect on catalase and maintains the stability of intracellular ROS levels to a certain extent.

The different toxic effects of metalaxyl and metalaxyl-M on Tubifex tubifex.

Metalaxyl and Metalaxyl-M are the fungicides that widely used in many countries. In this study, the environmental behaviors between metalaxyl and metalaxyl-M in Tubifex tubifex (T. tubifex) were quantitative analyzed by using a high performance liquid chromatography with photo-diode-array-detector (HPLC-DAD). Results demonstrated that there was no significant difference (p > 0.05) in the concentration of metalaxyl and metalaxyl-M in T. tubifex during the exposure process. However, the dissipation behaviors of metalaxyl and metalaxyl-M in T. tubifex were different (p < 0.05) during the non-exposure culture process. Meanwhile, the toxic effects were also evaluated by comparing the different influences of these two compounds on related physiological indicators, and functional enzyme activities. The survival rates of T. tubifex were 63.33 ± 15.28% (20 mg L-1), 63.33 ± 5.77% (200 mg L-1) treated with metalaxyl and were 50.00 ± 10.00% (20 mg L-1), 46.67 ± 11.55 (200 mg L-1) treated with metalaxyl-M at the non-exposure culture process. The autotomy rates were increased significantly compared with the initial in all treatments. Besides, the activities of CAT, SOD, and GST in T. tubifex were also inhibited by metalaxyl and metalaxyl-M treatments. Finally, the high-throughput transcriptome sequencing technology was applied to investigate the metabolic pathways of target analytes in T. tubifex, and results proved that the metabolic pathways associated with human diseases (such as viral myocarditis) were up-regulated expression for metalaxyl and metalaxyl-M treatments, and metalaxyl-M up-regulated more significantly. All the results demonstrated that metalaxyl-M had a higher toxicity than metalaxyl on T. tubifex.

Assessing single effects of sugarcane pesticides fipronil and 2,4-D on plants and soil organisms.

The continuous growth in global population since the beginning of the 20th century result in the necessity of food and energy provision favoring the intensive use of agricultural products such as pesticides. Although pesticides are important to prevent losses in the conventional chemically based agriculture, they frequently present side effects, which goes against agricultural production. The use of pesticides cause direct and indirect effects to soil organisms unbalancing essential soil processes (e.g. primary production, organic matter decomposition, nutrient cycling). Under tropical conditions, very little is known regarding the effects of pesticides to terrestrial organisms. Hence, the aim of the present study was to assess the ecotoxicological effects of the herbicide DMA® 806 BR (active ingredient: 2,4-D) and the insecticide Regent® 800 WG (active ingredient: fipronil), on terrestrial plant species (the dicot Raphanus sativus var. acanthioformis and the monocot Allium cepa), and soil invertebrates (the collembolan Folsomia candida and the enchytraeid Enchytraeus crypticus), using natural (NS) and artificial soils (TAS). For both pesticides, negative effects on non-target species were observed at concentrations lower than the doses recommended to prevent pests in sugarcane fields. For both soils, the dicot species was the most affected by the herbicide (R. sativus > A. cepa > F. candida > E. crypticus) and the collembolan species was the most affected by the insecticide (F. candida > E. crypticus = R. sativus = A. cepa). Although the order of the organisms' sensitivity for both pesticides was the same in both soils, results showed that the extent of the effects was soil dependent. Considering the ecologically relevant concentrations tested, and their severe effects to non-target organisms, it may be concluded that the use of fipronil and 2,4-D under recommended conditions may pose a risk to the terrestrial environment.

Chemicals associated with biodegradable microplastic drive the toxicity to the freshwater oligochaete Lumbriculus variegatus.

Microplastics (MPs) as complex synthetic pollutants represent a growing concern for the aquatic environment. Previous studies examined the toxicity of MPs, but infrequently used a natural particle control such as kaolin. The cause of toxicity, either the physical structure of the particles or chemical components originating from the MPs, has rarely been resolved. Moreover, the ecotoxicological assessment of biodegradable plastics has received little attention. To narrow down the main driver for toxicity of irregular biodegradable MPs, we conducted a series of 28-days sediment toxicity tests with the freshwater oligochaete Lumbriculus variegatus and recorded the number of worms and dry weight as endpoints. Therefore, MPs containing several biodegradable polymers were either mixed with the sediment or layered on the sediment surface with concentrations from 1 to 8.4% sediment dw-1. Kaolin particles were evaluated in parallel as particle control. Furthermore, aqueous leachates and methanolic extracts as MP equivalents as well as solvent-treated, presumably pure MPs were investigated after mixing them into the sediment. Our results reveal that MP mixed with the sediment induced stronger adverse effects than layered MP. Kaolin particles caused no adverse effects. In contrast, they enhanced dry weight in both applications. The impact of aqueous leachates was comparable to the control without MPs, whereas methanolic extracts affected the worm number at the highest concentration with 100% mortality. Solvent-treated, presumably pure MP resulted in mostly higher worm numbers when compared to untreated MPs mixed into the sediment. This study demonstrates that MPs mixed into the sediment affect L. variegatus more than MPs that are layered on the sediment surface. Kaolin as a natural, fine-sized particle control created somewhat favorable conditions for the worm. The main driver for toxicity, however, proved to be chemicals associated with the plastic product and its previous content.

Oxidative stress in benthic oligochaete worm, Tubifex tubifex induced by sublethal exposure to a cationic surfactant cetylpyridinium chloride and an anionic surfactant sodium dodecyl sulfate.

The present study was assessed to determine the in vivo toxic effects of a cationic surfactant, cetylpyridinium chloride (CPC), and an anionic surfactant, sodium dodecyl sulfate (SDS) in terms of oxidative stress biomarkers in benthic oligochaete worm Tubifex tubifex for 14 days. The investigation demonstrated that sublethal concentrations of CPC (0.0213, and 0.0639 mg L-1) and SDS (1.094 and 3.092 mg L-1)induced paramount alterations in the oxidative stress enzymes in Tubifex tubifex. Superoxide dismutase (SOD), glutathione S-transferase (GST), reduced glutathione (GSH), and glutathione peroxidase (GPx) exhibited an initial notable increase in their activities in the surfactants exposed worms at 1d and 7d of exposure period followed by consequential reduction at 14d exposure period with respect to control, while catalase (CAT) and malondialdehyde (MDA) activities markedly incremented gradually throughout the exposure periods. Through the construction of the correlation matrix and integrated biomarker response (IBR), the effects of CPC and SDS on Tubifex tubifex were distinguished. These results indicate that exposure to these cationic and anionic surfactants modulates the levels of oxidative stress enzymes in Tubifex tubifex.

Gold and silver nanoparticles effects to the earthworm Eisenia fetida - the importance of tissue over soil concentrations.

To address and to compare the respective impact of gold and silver nanoparticles (Au and Ag NPs) in soil invertebrate, the earthworm Eisenia fetida was exposed to soil containing 2, 10, and 50 mg/kg of Au and Ag in both nanoparticulate and ionic forms for 10 days. Both metal NPs were 2-15 times less bioavailable than their ionic forms, and displayed similar transfer coefficients from soil to earthworm tissues. Both metal NPs triggered the onset of an oxidative stress as illustrated by increased glutathione S-transferase levels, decreased catalase levels, and increased malondialdehyde concentrations. Protein carbonylation distinguished the nanoparticular from the ionic forms as its increase was observed only after exposure to the highest concentration of both metal NPs. Au and Ag NPs triggered DNA modifications even at the lowest concentration, and both repressed the expression of genes involved in the general defense and stress response at high concentrations as did their ionic counterparts. Despite the fact that both metal NPs were less bioavailable than their ionic forms, at equivalent concentrations accumulated within earthworms tissues they exerted equal or higher toxic potential than their ionic counterparts.Capsule: At equivalent concentrations accumulated within earthworm tissues Au and Ag NPs exert equal or higher toxic potential than their ionic forms.

Synergistic growth inhibition effect of TiO2 nanoparticles and tris(1,3-dichloro-2-propyl) phosphate on earthworms in soil.

The co-existence of organic pollutants and nanoparticles in the environment may lead to combined biological effects. The joint toxicity of pollutants and nanoparticles has been receiving increasing attention from researchers, but few studies have focused on soil biota due to the complexity of soil matrices. This study investigated the effects of tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) at 0, 5, and 25 mg/kg and nanoparticulate TiO2 (nTiO2) at 0, 500, and 2500 mg/kg in a 3 × 3 factorial arrangement of treatments for 28 days (d) on Eisenia fetida (earthworm). Compared with the control group (the 0 mg/kg TDCIPP + 0 mg/kg nTiO2 treatment), all other single (TDCIPP or nTiO2) and binary (TDCIPP + nTiO2) treatments except for the single 500 mg/kg nTiO2 treatment significantly reduced the weight gain rate of E. fetida. The binary treatments had significantly greater such effect than their corresponding single treatments, exhibiting a synergistic toxicity between TDCIPP and nTiO2 on the growth of E. fetida. Since TDCIPP and nTiO2 had no significant effect on their concentrations in the soil or in E. fetida during binary exposure, the synergistic toxicity could be a result of the superimposition of the toxicity pathways of TDCIPP and nTiO2. Transcriptomic analysis of E. fetida intestinal region revealed that exposure to 25 mg/kg TDCIPP or 2500 mg/kg nTiO2 affected nutrient-related or cell apoptosis and DNA damage related genes, respectively; their co-exposure greatly inhibited genes related to nutrient digestion and absorption, while causing abnormal transcription of genes related to the development and maintenance of E. fetida's muscles, leading to synergistic toxicity. These findings provide new insights into the environmental risks of organophosphorus flame retardants, nanoparticles, and their co-exposure.

Lumbriculus variegatus (oligochaeta) exposed to polyethylene microplastics: biochemical, physiological and reproductive responses.

Freshwater sediments are a repository of microplastics (MPs) resulting from inland anthropogenic activities. Benthic invertebrates, particularly endobenthic sediment-ingesting species such as the annelid Lumbriculus variegatus (blackworm), are commonly found in contaminated sediments where they likely find and ingest MPs. In the present study, L. variegatus was exposed to concentrations between 0.51 and 20 g kg-1 dry sediment of four size-classes of irregularly-shaped polyethylene MPs (PE-MPs; size-class A: 32-63, B: 63-125, C: 125-250 and D: 250-500 µm) for 48 h to assess their sub-cellular responses to particles ingested, and for 28 days to determine chronic effects on worm's reproduction and biomass. After the short-term exposure (48 h), number of PE-MPs in blackworms' gut were related to MPs concentration in the sediment. In general, PE-MPs ingestion by blackworms induced depletion of their energy reserves (e.g., sugars in all size classes and lipids in the size-classes of PE-MPs > 125 µm), concomitant with the activation of antioxidant and detoxification mechanisms (increased level of total glutathione in all size-classes, and increased glutathione-S-transferase activity in PE-MPs > 250 µm), preventing lipid peroxidation. In addition, it was observed a reduction of aerobic energy production (decreased activity of the electron transport system) and a slight increase in neurotransmission (cholinesterase activity). After a long-term exposure (28 d), the presence and ingestion of PE-MPs did not affect reproduction and biomass of L. variegatus. The activation and efficiency of the antioxidant and detoxification mechanisms allied with the anatomy and physiology of L. variegatus, its feeding strategy and potentially dynamic ingestion/egestion capacity seem to be key features preventing MP deleterious effects under short- and chronic-exposures. Considering the MPs levels reported for freshwater sediments, and despite evidence of MPs ingestion and some sub-organismal effects, our results suggest no adverse impacts of PE-MPs contamination on L. variegatus populations fitness. This study applies an integrative approach in which data concerning the ingestion of different sized MPs and subsequent sub-cellular and apical responses are delivered, raising knowledge on endobenthic invertebrates' strategies to potentially overcome MP toxicity in field contaminated sites.