Pollutant-induced alterations of granulocyte morphology in the earthworm Eisenia foetida

Copper toxicity to earthworms: A comprehensive review and meta-analysis

Copper can accumulate in agricultural topsoil through the use of Cu-based fungicides, which may harm soil organisms such as earthworms. This study aimed at reviewing the effects of copper on earthworms at different levels of biological organization, and to determine critical values of copper toxicity to earthworms using a meta-analysis and accounting for lethal and sub-lethal effects and different earthworm species and exposure conditions. Endpoints at the sub-individual level were more sensitive than at higher levels of organization. At the individual level, the most sensitive endpoints were reproduction and growth (hatching success, hatchling growth). Hormetic growth was clearly recognized at copper concentrations less than 80 mg kg-1 in dry soil. However, effects at the sub-individual level already occurred at lower concentrations. Considering all the exposure conditions, the calculated weighted means were 113 mg Cu kg-1 dry soil (95% CI -356; 582) for the LC50 (lethal concentration for 50% of the exposed individuals), 94.6 mg Cu kg-1 dry soil (95% CI 14.0; 175) for the EC50 reproduction, and 144 mg Cu kg-1 dry soil (95% CI -12.6; 301) for the EC50 growth or weight change. When accounting for the origin of the soil, earthworms were five times more sensitive to copper (LC50) in natural than in artificial soils. The different factors affecting Cu toxicity to earthworms explain the high variability of these values, making it difficult to derive thresholds. However, considering the potential negative effects of copper on earthworms, attention should be given to the more sustainable use of human-contributed copper in agricultural soils.

Morphological and functional alterations in hemocytes of Mytilus galloprovincialis exposed in high-impact anthropogenic sites

The work aimed to study the induction of morphological alterations in M. galloprovincialis in the field and its suitability to be integrated into a sensitive, simple, and cost-effective cell-based multimarker approach for the detection of the stress status induced by pollution in coastal marine environments in view of ecotoxicological biomonitoring and assessment application. Cellular morphometric alterations was paralleled by the analysis of standardized biomarkers such as lysosomal membrane destabilization, and genotoxocity biomarkers such as micronuclei and binuclated cells frequencies were investigated. The study was carried out by means of a transplanting experiment in the field, using caged organisms from an initial population exposed in the field in two multi-impacted coastal sites of the central Mediterranean area, Bagnoli in the eastern Tyrrhenian Sea and Augusta-Melilli-Priolo in the western Ionian Sea. Capo Miseno (NA) for the Tyrrhenian area and Brucoli (ME) for the Ionian area were chosen as control sites. Hemocyte enlargement and filopodial elongation increased frequencies were observed in organisms exposed to the impacted sites. These morphometric alterations showed strong agreement with the lysosomal membrane destabilization and biomarkers of genotoxicity, suggesting their usefulness in detecting the pollutant-induced stress syndrome related to genotoxic damage.

A comparative account of coelomocyte of earthworm ecotypes with reference to its morphology, morphometry, density, phagocytosis, autofluorescence, and oxidative status

Earthworms inhabit different strata of moist soil. Epigeic and endogeic earthworms prefer superficial and inner stratum of soil respectively, whereas, semiaquatic species are distributed around hydrated soil near ponds and lakes. Coelomocytes, the chief immunoeffector cells of coelomic origin, perform diverse physiological functions like phagocytosis, maintenance of cellular homeostasis, and acid-base balance of coelomic fluid, graft rejection, elicitation of cytotoxic, and oxidative responses under the challenges of pathogens and toxins. The present study aims to analyze selected morphological and functional parameters in three differentially adapted Indian earthworms of nonsimilar habitats. Coelomocytes of Glyphidrilus tuberosus (Stephenson, 1916) (semiaquatic), Perionyx excavatus (Perrier, 1872) (epigeic), and Eutyphoeus orientalis (Beddard, 1883) (endogeic) were isolated for morphological and morphometric analyses and subjected to determination of phagocytic, oxidative, and cytotoxic responses. Activities of phenoloxidase, pro, and antioxidant enzymes, and autofluorescence were determined in the extruded coelomocytes of earthworms of three contrasting habitats. The differential result may be correlated with species-specific responses and variation in habitat preference and related adaptation.

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.

Toxicity of isoprocarb to earthworms (Eisenia fetida): Oxidative stress, neurotoxicity, biochemical responses and detoxification mechanisms

Isoprocarb (IPC) is a conventional carbamate with high insecticidal activity, however, generalized use of it may cause soil contamination and adversely implicate non-target biota. Following OECD standardized toxicological protocols, the toxic effects of IPC on Eisenia fetida at lethal and sublethal concentrations were examined to elucidate its toxic modes of action as well as biochemical and detoxification responses of E. fetida. Acute toxicity tests showed that IPC induced a concentration-dependent rise of mortality, with LC₅₀ of 8.20 μg/cm² (48 h) in FPCT and 3.37 mg/kg (14 d) in AST, respectively. The ecotoxicological effects of IPC chronic exposure were measured by physiochemical, qRT-PCR and western blot analysis. Specifically, ROS, MDA and 8-OHdG contents were enhanced and T-AOC, SOD, CAT and POD activities diminished with increasing concentrations. While activities of CYP3A4 and CarE as well as expressions of Hsp70, GPx and GST were elevated upon IPC treatments, responsible for detoxifying mechanisms as implied by principal component analysis (PCA). Meanwhile, IPC diminished NRRT and inhibited AChE activities along with expressions of AChE-related genes. All these striking alterations between IPC-exposed earthworms and controls were illustrated in PCA model. More importantly, growth, reproductive and regenerative toxicity of IPC were observed with reduced cast production and soluble protein content, suppressed ANN protein and gene expressions, reversely modulated TCTP and Sox2 gene and protein, respectively. Taken together, deleterious perturbations could be induced by IPC in biophysiological homeostasis of E. fetida primarily through oxidative stress and neural dysfunction. This study not only highlighted potential hazard of IPC to earthworms in the terrestrial ecosystem, but also expounded upon mechanisms underlying toxic modes of action for IPC and detoxification of earthworms.

Impact of Intensive Farming on Soil Heavy Metal Accumulation and Biomarkers Responses of Earthworms Eisenia andrei

In this work, we propose to evaluate the effect of agriculture intensification under greenhouses on the biochemical and transcriptomic responses of the earthworms Eisenia andrei. This work was conducted on two sites in Téboulba and Sahline (Monastir governorate) and a control site in an experimental plot that is undergoing organic farming. For this purpose, the earthworms Eisenia andrei were exposed to the soils during 7 and 14 days. The physicochemical properties of the soils were analyzed. The biochemical biomarkers of metallothioneins (MTs) and malondialdehyde (MDA) accumulations were also assessed. Moreover, the gene expression level of the MTs was analyzed. The results of our study revealed a significant trace element accumulation accompanied by a high level of MDA and MT proteins. Moreover, a significant expression of the MT gene was observed in earthworms exposed to the soils from Sahline and Téboulba. Hence, this work reveals that intensive agriculture can affect the biological responses of earthworms and consequently, the soil's biofertility.

Effects of organic mercury on Mytilus galloprovincialis hemocyte function and morphology

Abstract

Filter-feeding organisms accumulate xenobiotics and other substances in their tissues. They can be useful as sentinel organisms in biomonitoring of the marine compartment. Bivalve cellular immunity is ensured by phagocytosis and cytotoxic reactions carried out by hemocytes in a network with humoral responses. These can be affected by chemical contaminants in water that can be immunosuppressors also at a low concentration increasing the sensibility to pathogens. This work is an attempt to individuate cellular markers for pollution detection, investigating the effect of methylmercury (CH₃HgCl) at different concentrations on the activity and hemocyte morphology of the Mediterranean mussel, Mytilus galloprovincialis. We assessed the effect of three sub-lethal concentrations of the organometal on the cellular morphology, the efficacy of phagocytosis toward yeast cells, the alteration of the lysosomal membrane and the ability to release cytotoxic molecules. The results provide information on the alteration of hemocyte viability, modification of the morphological and cytoskeletal features and besides the cellular spreading, intrinsic ability of motile cells was used as a complementary investigation method. Exposure to the contaminant affected the percentage of phagocytosis and the phagocytosis index. Moreover, morphological and cytoskeleton alteration, caused by the pollutant, leads to reduced ability to incorporate the target and adhere to the substrate and the low ability of cells to retain neutral red could depend on the effects of methylmercury on membrane permeability. These results reinforce the use of the Mediterranean mussel as model for the evaluation of environmental quality in aquatic ecosystems integrating the novel information about hemocyte functions and morphology sensibility to organic mercury.

Graphic abstract

Nanomaterials and Annelid Immunity: A Comparative Survey to Reveal the Common Stress and Defense Responses of Two Sentinel Species to Nanomaterials in the Environment

Simple Summary

Nanotechnology is a dynamically developing field producing large amounts of nanocompounds that are applied in industry, daily life, and health care. During production, use, and waste these materials could end up in water or soil. Large scale contaminations of our environment are a threat to public health. Pollution can have harmful effects on the immune system, as revealed by numerous studies in humans and other vertebrates. The relative simplicity of invertebrate immune functions offers potentially sensitive and accessible means of monitoring the effects and complex interactions of nanoparticles which ultimately affect host resistance. Among terrestrial and freshwater invertebrates, earthworms and leeches are the “keystone” species to evaluate the health of our ecosystems. In this review we compare the conserved stress and immune responses of these invertebrate model organisms toward nanoparticles. The obtained knowledge provides exciting insights into the conserved molecular and cellular mechanisms of nanomaterial-related toxicity in invertebrates and vertebrates. Understanding the unique characteristics of engineered nanoproducts and their interactions with biological systems in our environment is essential to the safe realization of these materials in novel biomedical applications.

Abstract

Earthworms and leeches are sentinel animals that represent the annelid phylum within terrestrial and freshwater ecosystems, respectively. One early stress signal in these organisms is related to innate immunity, but how nanomaterials affect it is poorly characterized. In this survey, we compare the latest literature on earthworm and leeches with examples of their molecular/cellular responses to inorganic (silver nanoparticles) and organic (carbon nanotubes) nanomaterials. A special focus is placed on the role of annelid immunocytes in the evolutionarily conserved antioxidant and immune mechanisms and protein corona formation and probable endocytosis pathways involved in nanomaterial uptake. Our summary helps to realize why these environmental sentinels are beneficial to study the potential detrimental effects of nanomaterials.

Washing soda induced alteration of the differential cell count, nonself surface adhesion efficacy and nuclear morphology of the polyphenotypic cells of a freshwater sponge of India

Washing soda has been identified as a precarious contaminant of the freshwater ponds and lakes, the natural habitat of Eunapius carteri. Treatment of sublethal concentrations of washing soda for 384 hours exhibited a significant decrease in the densities of blast like cells, small and large amoebocytes. The percentage occurrence of granular cells and archaeocytes yielded a marked increase against the experimental concentrations of washing soda. Washing soda mediated alterations in the differential cell densities of E. carteri indicative of a state of physiological stress and an undesirable shift in the cellular homeostasis of the organism distributed in polluted environment. Experimental exposure of washing soda yielded a significant increase in the cellular dimensions of large amoebocytes and archaeocytes. Prolonged treatment with washing soda presented a gross reduction in nonself surface adhesion efficacy of E. carteri cells. Experimental concentrations of washing soda resulted in a dose dependent increment in the frequencies of binucleation and micronucleation in the cells of E. carteri. The data were indicative of a high level of genotoxicity of washing soda in E. carteri. The present investigation provides an important information base in understanding the toxin induced chemical stress on the archaic immune defense of a primitive urmetazoa.

Environmental pollutants, pathogens and immune system in earthworms

Earthworms also known as farmer's friends are natural tillers of soil. They belong to Phylum Annelida and class Oligochaeta. Acid soils with organic matter and surface humus maintain the largest fauna of worms and earthworms. Due to their habitat in soil, they are constantly exposed to microbes and pollution generated by anthropogenic sources. Studies have revealed that damage of the immune system of earthworms can lead to alterations of both morphological and cellular characteristics of worms, activation of signalling pathways and can strongly influence their survival. Therefore, the understanding of the robust immune system in earthworms has become very important from the point of view of understanding its role in combating pathogens and pollutants and its role in indicating the soil pollution. In this article, we have outlined the (i) components of the immune system and (ii) their function of immunological responses on exposure to pollutants and pathogens. This study finds importance from the point of view of ecotoxicology and monitoring of earthworm health and exploring the scope of earthworm immune system components as biomarkers of pollutants and environmental toxicity. The future scope of this review remains in understanding the earthworm immunobiology and indicating strong biomarkers for pollution.

The ascidian Styela plicata hemocytes as a potential biomarker of marine pollution: In vitro effects of seawater and organic mercury

Toxic metals, such as mercury, contribute substantially to anthropogenic pollution in many estuarine environments. Animals living in those environments, particularly invertebrate filter feeders like tunicates, can be used as bioindicators. In an attempt to identify cellular markers for revealing pollution, this study examined in vitro the effects of different concentrations of methyl mercury on Styela plicata hemocytes. The harvested hemocytes from S. plicata that were exposed to the metal had a significant mortality, cellular count and morphometric alterations. These findings provided evidence of MeHg immunotoxic effects on S. plicata, resulting in hemocyte death and morphological changes induced by cytoskeleton alterations. Thus, a morphometric cellular parameter, such as spreading ability, was used as a complementary method for differentiation between hemocytes treated with a marine solution (as a negative control) and hemocytes incubated with methylmercury and/or Sicilian seawater samples.

Metallothionein 2 and Heat Shock Protein 72 Protect Allolobophora chlorotica from Cadmium But Not Nickel or Copper Exposure: Body Malformation and Coelomocyte Functioning

Earthworms serve as good indicators of heavy metal contamination due to their innate sensitivity towards soil pollution. However, to date, not many studies have focused on endogeic earthworms, such as the omnipresent Allolobophora chlorotica. The current study was designed to verify whether this earthworm could serve as a novel distinctively susceptible species for environmental contamination studies. We show that the dermal exposure to Cu, Ni, and Cd affected the mortality and morphology of A. chlorotica, and the number and functioning of coelomocytes. These features particularly were pronounced in animals treated with Ni and Cu and interestingly to a lesser extend with Cd. In contrast, Cd induced a strong expression of metallothioneins (MT-2) and heat shock proteins (HSP72). The presence of MT-2 was detected not only in coelomocytes but also in the intestine, blood vessels, and epidermis. In conclusion, Allolobophora chlorotica coelomocytes are adopted to respond differentially to various heavy metals, generating powerful response towards potentially most dangerous exogenous non-essential elements.

Mercury induced haemocyte alterations in the terrestrial snail Cantareus apertus as novel biomarker

The aim of the present work was to study the response of a suite of cellular and biochemical markers in the terrestrial snail Cantareus apertus exposed to mercury in view of future use as sensitive tool suitable for mercury polluted soil monitoring and assessment. Besides standardized biomarkers (metallothionein, acetylcholinesterase, and lysosomal membrane stability) novel cellular biomarkers on haemolymph cells were analyzed, including changes in the spread cells/round cells ratio and haemocyte morphometric alterations. The animals were exposed for 14 days to Lactuca sativa soaked for 1h in HgCl2 solutions (0.5 e 1 μM). The temporal dynamics of the responses were assessed by measurements at 3, 7 and 14 days. Following exposure to HgCl2 a significant alteration in the relative frequencies of round cells and spread cells was evident, with a time and dose-dependent increase of the frequencies of round cells with respect to spread cells. These changes were accompanied by cellular morphometric alterations. Concomitantly, a high correspondence between these cellular responses and metallothionein tissutal concentration, lysosomal membrane stability and inhibition of AChE was evident. The study highlights the usefulness of the terrestrial snail C. apertus as bioindicator organism for mercury pollution biomonitoring and, in particular, the use of haemocyte alterations as a suitable biomarker of pollutant effect to be included in a multibiomarker strategy.

Multibiomarker response in the earthworm Eisenia fetida as tool for assessing multi-walled carbon nanotube ecotoxicity

Carbon nanotubes have received a great attention in the last years thanks to their remarkable structural, electrical, and chemical properties. Nowadays carbon nanotubes are increasingly found in terrestrial and aquatic environment and potential harmful impacts of these nanoparticles on humans and wildlife are attracting increasing research and public attention. The effects of carbon nanotubes on aquatic organisms have been explored by several authors, but comparatively the information available on the impact of these particles on soil organisms is much less. Earthworms have traditionally been considered to be convenient indicators of land use impact and soil fertility. The aim of this work was to study the integrated response of a suite of biomarkers covering molecular to whole organism endpoints for the assessment of multi-walled carbon nanotube (MWCNTs) effects on earthworms (Eisenia fetida) exposed to spiked soil. Results showed that cellular and biochemical responses, such as immune cells morphometric alterations and lysosomal membrane destabilization, acetylcholinesterase inhibition and metallothionein tissue concentration changes, showed high sensitivity to MWCNTs exposure. They can improve our understanding and ability to predict chronic toxicity outcomes of MWCNTs exposure such as reproductive alterations. In this context although more investigation is needed to understand the mechanistic pathway relating the biochemical and cellular biomarker analyzed to reproductive alterations, the obtained results give an early contribution to the future development of an adverse outcomes pathways for MWCNTs exposure.

DNA damage in different Eisenia andrei coelomocytes sub-populations after in vitro exposure to hydrogen peroxide

Earthworms play an essential role in providing soil fertility and may represent an important soil contamination bio-indicator. They are able to ingest soil particles, adsorb substances throughout the intestinal epithelium into the coelomic cavity, where chemicals can come in direct contact with coelomic fluid. Earthworm coelomic fluid shelters leucocytes (coelomocytes) that differ significantly both structurally and functionally. Cellular variability could lead to different susceptibility towards contaminants possibly present in soil ecosystem. In order to define population specific dose response to chemicals and to identify a homogeneous cell population to be used as a relevant biomarker, we investigated different coelomocytes subpopulation, obtained by Percoll density gradient centrifugation (5–35 %), exposed ex vivo to H₂O₂ in the range of concentration 15–120 µM. DNA damage levels were assessed by the comet assay on unseparated coelomocytes and on three enriched cellular fractions (light, medium and heavy density subpopulations). All tested samples showed a dose–response genotoxic effect following H₂O₂ exposure. Moreover, light density sub-population appeared more susceptible to oxidative insult highlighted by a significant increase in DNA damage indexes at lower concentrations of H₂O₂. Present data suggested that in these experimental condition coelomocytes light fraction may represent a more sensitive biomarker of genotoxic insult.

Morphological alteration, lysosomal membrane fragility and apoptosis of the cells of Indian freshwater sponge exposed to washing soda (sodium carbonate)

Washing soda is chemically known as sodium carbonate and is a component of laundry detergent. Domestic effluent, drain water and various anthropogenic activities have been identified as major routes of sodium carbonate contamination of the freshwater ecosystem. The freshwater sponge, Eunapius carteri, bears ecological and evolutionary significance and is considered as a bioresource in aquatic ecosystems. The present study involves estimation of morphological damage, lysosomal membrane integrity, activity of phosphatases and apoptosis in the cells of E. carteri under the environmentally realistic concentrations of washing soda. Exposure to washing soda resulted in severe morphological alterations and damages in cells of E. carteri. Fragility and destabilization of lysosomal membranes of E. carteri under the sublethal exposure was indicative to toxin induced physiological stress in sponge. Prolonged exposure to sodium carbonate resulted a reduction in the activity of acid and alkaline phosphatases in the cells of E. carteri. Experimental concentration of 8 mg/l of washing soda for 192 h yielded an increase in the physiological level of cellular apoptosis among the semigranulocytes and granulocytes of E. carteri, which was suggestive to possible shift in apoptosis mediated immunoprotection. The results were indicative of an undesirable shift in the immune status of sponge. Contamination of the freshwater aquifers by washing soda thus poses an alarming ecotoxicological threat to sponges.

Indication of metal homeostasis disturbance in earthworm Eisenia fetida after exposure to semi-solid depot sludge

Treated sewage sludge is commonly used in agriculture as fertilizer. It is, therefore, necessary to determine possible detrimental influences of sludge application on soil contamination and accumulation of contaminants in tissues of terrestrial animals, which in the long run could also have undesirable effects on humans. With that aim, the study was performed using earthworm Eisenia fetida as test organism and semi-solid depot sludge from a wastewater treatment plant as exposure media. The concentrations of 26 metals/metalloids were determined in depot sludge, and their bioaccumulation was estimated in whole tissue of E. fetida, and for the first time in the soluble tissue fraction, which represents metal fraction available for metabolic requirements and toxic effects. Obtained results have revealed acceptable levels of several elements (Cd, Cr, Cu, Ni, Pb, Zn) in depot sludge, when compared to currently valid regulations, and only moderate accumulation of some elements (e.g. As, Ba, Cd, Co, Fe, Tl, V, and Zn) in earthworms, as a consequence of exposure to depot sludge. However, a concentration increase after exposure to depot sludge was observed in E. fetida for several elements (Cd, Mo, and Zn), which were present in lower concentrations in the exposure mixtures than in soil. Contrary, a concentration decrease was observed for Cs, Mn, and Rb, although they were present in higher concentrations in depot sludge than in soil. It was an indication of disturbance in metal homeostasis in earthworms, possibly caused by exposure to complex mixture of contaminants present in depot sludge. The cumulative effect of exposure to a number of various contaminants (inorganic, organic, microbiological and pharmaceutical), even if each of them was not present in very high concentrations, could have caused distress in earthworms exposed to depot sludge.

Antioxidant and oxidative stress related responses in the Mediterranean land snail Cantareus apertus exposed to the carbamate pesticide Carbaryl

The aim of the present work was to study the alterations of the antioxidant defenses and the overall susceptibility to oxidative stress of the terrestrial snail Cantareus apertus exposed to the carbamate pesticide Carbaryl at a low environmentally realistic concentration. The animals were exposed to Lactuca sativa soaked for 1h in 1μM Carbaryl. The temporal dynamics of the responses was assessed by measurements at 3, 7 and 14days of exposure. C. apertus exposed to Carbaryl activates a number of enzymatic antioxidant responses, represented by the early induction of catalase, glutathione peroxidase, glutathione reductase, followed by a delayed induction of superoxide dismutase. Concomitantly, a derangement of the total oxyradical scavenging of the tissues was observed, suggesting an overall impairment of the tissue capability to neutralize ROS probably resulting from the overall negative balance between enzymatic antioxidant defense capability and oxidative stress intensity. This negative balance exposed the animals to the risk of oxidative stress damages including genotoxic damage. Compared to acetylcholinesterase inhibition, the antioxidant responses developed to Carbaryl exposure at the low concentration utilized showed a greater percentage variation in exposed organisms. The results pointed out the high sensitivity of the antioxidant and oxidative stress related responses to Carbaryl exposure at an environmental realistic concentration, demonstrating their usefulness in environmental monitoring and risk assessment. The study highlights also the usefulness of the terrestrial snail C. apertus as potential bioindicator species for assessing the risk of pesticide environmental contamination.

Metallothionein induction in the coelomic fluid of the earthworm Lumbricus terrestris following heavy metal exposure: a short report

Earthworms are useful bioindicator organisms for soil biomonitoring. Recently the use of pollution biomarkers in earthworms has been increasingly investigated for soil monitoring and assessment. Earthworm coelomic fluid is particularly interesting from a toxicological perspective, because it is responsible for pollutant disposition and tissue distribution to the whole organism. The aim of the present work was to study the effect of heavy metal exposure on metallothionein (Mt) induction in the coelomic fluid of Lumbricus terrestris in view of future use as sensitive biomarker suitable for application to metal polluted soil monitoring and assessment. L. terrestris coelomic fluid showed a detectable Mt concentration of about 4.0 ± 0.6 μg/mL (mean ± SEM, n = 10) in basal physiological condition. When the animals were exposed to CuSO₄ or CdCl₂ or to a mixture of the two metals in OECD soils for 72 h, the Mt specific concentration significantly (P < 0.001) increased. The Mt response in the coelomic fluid perfectly reflected the commonly used Mt response in the whole organism when the two responses were compared on the same specimens. These findings indicate the suitability of Mt determination in L. terrestris coelomic fluid as a sensitive biomarker for application to metal polluted soil monitoring and assessment.

Using biomarkers in an evolutionary context: lessons from the analysis of biological responses of oligochaete annelids to metal exposure

Anthropogenic activities may lead to the accumulation of inorganic and organic compounds in topsoils. Biota living in close contact with contaminated soils may experience stress at different levels of biological organization throughout the continuum from molecular to community level. Biological responses observed at the individual or infra-individual level of biological organization led to the development of biomarkers. The development of biomarkers consists often in evidencing biological modifications following a contaminant stress in laboratory conditions, using naïve organisms and it is sometime proposed to use the biological state of individuals from sentinel species collected in the field to evaluate the level of environmental exposure. However, considering the possibility of local adaptation following long-term exposure, organisms response sampled in the field may substantially differ from laboratory specimens. In this review, we discuss this point focusing on the definition and validity of molecular biomarkers of metal pollution using earthworms of the Lumbricidae family.

Acetylcholinesterase as a biomarker in environmental and occupational medicine: new insights and future perspectives

Acetylcholinesterase (AChE) is a key enzyme in the nervous system. It terminates nerve impulses by catalysing the hydrolysis of neurotransmitter acetylcholine. As a specific molecular target of organophosphate and carbamate pesticides, acetylcholinesterase activity and its inhibition has been early recognized to be a human biological marker of pesticide poisoning. Measurement of AChE inhibition has been increasingly used in the last two decades as a biomarker of effect on nervous system following exposure to organophosphate and carbamate pesticides in occupational and environmental medicine. The success of this biomarker arises from the fact that it meets a number of characteristics necessary for the successful application of a biological response as biomarker in human biomonitoring: the response is easy to measure, it shows a dose-dependent behavior to pollutant exposure, it is sensitive, and it exhibits a link to health adverse effects. The aim of this work is to review and discuss the recent findings about acetylcholinesterase, including its sensitivity to other pollutants and the expression of different splice variants. These insights open new perspective for the future use of this biomarker in environmental and occupational human health monitoring.

Dermal exposure to immunostimulants induces changes in activity and proliferation of coelomocytes of Eisenia andrei

Due to the specific habitat conditions in which they live, earthworms are constantly exposed to pathogens. Consequently, they have evolved various immuno-defense mechanisms, including cellular (coelomocytes) and humoral responses, which may help to eliminate deleterious micro-organisms but also repair and/or protect host cells and tissues. Similar to mammalian phagocytes, coelomocytes can kill ingested pathogens with reactive oxygen species (ROS) and nitric oxide. In the present work, we studied the effects of the dermal exposure of Eisenia andrei earthworms to different immuno-stimulants: phorbol-12-myristate-13-acetate (PMA), lipopolysaccharide (LPS) or concanavalin A (ConA). After 3 days of treatment with all immuno-stimulants, decreased numbers and changed composition of the coelomocytes were observed. The immuno-stimulants also induced numerous changes in bactericidal activity, including ROS production. Furthermore, all stimulants increased cell proliferation while only LPS-treatment significantly elevated apoptosis of coelomocytes. These results demonstrate that in vivo treatment of earthworms with immuno-stimulants induces various changes in their coelomocyte response.

Integrated biomarker analysis in the earthworm Lumbricus terrestris: application to the monitoring of soil heavy metal pollution

As recently recognized exposure and effect assessment of soil contaminants on soil biota is necessary for decision-making related to ecosystem services and habitat protection, establishment of remediation procedures, or pollution monitoring programs. Therefore, biological approaches to soil monitoring, such as the measurement of biomarkers in soil bioindicator organisms, have recently received increasing attention. The aim of the present work was to assess the performance of a suite of cellular and biochemical biomarkers in native earthworms (Lumbricus terrestris) sampled in heavy metal contaminated sites in view of the validation of this biomarker approach in soil monitoring and assessment. Besides well known and standardized biomarkers such as lysosomal membrane stability, metallothionein tissue concentration and acetylcholinesterase activity, novel potential biomarkers such as changes in blood hemoglobin concentration and granulocyte morphometric alterations were analyzed. Both univariate and multivariate (PCA) statistical analysis applied to the data set revealed that the integrated multi-marker approach in native L. terrestris under field conditions produces a sensitive and cost-effective assessment of heavy metal soil pollution, which could be incorporated as a descriptor of environmental status in future soil biomonitoring programmes.

Biomarker response in the earthworm Lumbricus terrestris exposed to chemical pollutants

Earthworms are important organisms for the soil ecosystem. They are sensitive to toxic chemicals and represent useful bioindicator organisms for soil biomonitoring. Recently the use of biomarkers in earthworms has been increasingly investigated for soil monitoring and assessment purpose. The aim of the preset paper was to analyze the pollutant-induced response of a suite of cellular and biochemical biomarkers in the earthworm Lumbricus terrestris exposed to copper sulphate or methiocarb in OECD soil at the maximal concentrations recommended in agriculture. These responses were compared to lifecycle parameters such as survival, growth and reproduction. Granulocyte morphometric alteration, lysosomal membrane stability, metallothionein concentration, and acetylcholinesterase activity were considered. In either copper sulphate or methiocarb exposure conditions the mean percentage variation of the pollutant-induced molecular and cellular biomarkers was consistent with the whole organism end-point responses. In particular pollutant-induced granulocyte enlargement, detected in either copper sulphate or methiocarb exposed organisms, showed to be a potential general biomarker that may be directly linked to organism health. Compared to the other biological responses to pollutants, it showed high sensitivity to pollutant exposure suggesting its possible applications as a sensitive, simple, and quick general biomarker for monitoring and assessment applications.