Metallothionein responses in the earthworm Lampito mauritii (Kinberg) following lead and zinc exposure: A promising tool for monitoring metal contamination

Efficacy of Vermiremediation to Remove Contaminants from Soil

BACKGROUND

In addition to improving soil fertility and crop production, earthworms have been found to be useful in the removal of contaminants from soil, known as vermiremediation. Previous studies on vermiremediation have focused primarily on organic wastes, with relatively less attention paid to inorganic contaminants. In addition, some basic terms used in environmental health studies have often not been properly clarified.

OBJECTIVES

The present study is a review of the state of the literature on the effectiveness of using earthworms to remediate organic and inorganic (metal) soil contaminants. Earthworms' actions in remediation of organic and inorganic contaminants are described. Some terms that are used interchangeably in environmental health are clarified. The challenges and limitations of vermiremediation are highlighted.

METHODS

A systematic literature search was conducted to access online academic publications indexed in Google Scholar, PubMed, Scopus, Clarivate Analytics (Web of Science), ScienceDirect, ResearchGate and Springer Link. A total of 165 publications on the subject matter were accessed, out of which 47 were used for the review.

DISCUSSION

Empirical and theoretical information from the literature showed evidence of the significant contributions of earthworms to the removal of soil organic contaminants and metals. Earthworms indirectly facilitate the conversion of organic contaminants by promoting microbial and enzyme activities. Some organic contaminants are directly taken up through dermal and intestinal absorption and accumulated by preferential sequestration in sub-organismic and tissue fractions of earthworms. Metals are directly removed and accumulated by the mechanism of detoxification and sequestration, via metallothioneins induction. The terms 'contaminants' and 'pollutants' have different meanings and should not be used interchangeably. Although vermiremediation presents an ideal clean-up technique, it is limited in application to only mildly contaminated soil environments. Ethical concerns should not pose a serious issue because vermiremediation simply takes advantage of earthworms' natural soil-conditioning abilities. Many vermiremediation processes, especially of organic wastes, are harmless to earthworms, improving the soil for their growth and survival.

CONCLUSIONS

Vermiremediation presents a good long-term biological option to clean up mildly contaminated soil. It may be deployed as a secondary measure to rid the soil of residual contaminants after applying physicochemical remediation techniques to an overtly polluted soil environment.

COMPETING INTERESTS

The authors declare no competing financial interests.

Quantitative immunodetection of metalloprotein II in Perinereis aibuhitensis after heavy metal exposure

The metal detoxification mechanism is essential for the accumulation activity of some polychaetes. In order to investigate the detoxification function of metalloprotein II in polychaete Perinereis aibuhitensis, a recombinant fusion protein of MP II was successfully expressed in vitro and an anti-MP II polyclonal antibody was got. The tissue distribution of MP II in P. aibuhitensis and the protein expression under Cd, Pb and Zn exposure were detected by ELISA with this antibody. The results showed that MP II was higher in the intestine of P. aibuhitensis, followed by the body wall and parapodium. Cd, Zn and Pb exposure can induced MP II expression, but the change trend of MP II under various heavy metal exposure was different. The amount of MP II induced in P. aibuhitensis increased with the rises of Cd concentration, but there is no significant relationship between Zn and Pb concentration and MP II level.

Enzymatic and non-enzymatic detoxification in Lycosa terrestris and Pardosa birmanica exposed to single and binary mixture of copper and lead

Organisms employ various enzymatic and non-enzymatic detoxification mechanisms to minimize the harmful effects of metal pollution in the terrestrial environment. We examined the effects of copper (Cu), lead (Pb) and their mixture (Cu + Pb) on glutathione (GSH), metallothionein (MTs), cytochrome P450 (CYP 450), carboxylesterase (CarbE), acetylcholinesterase (AchE) and glutathione S-transferase (GST) in Lycosa terrestris and Pardosa birmanica via two exposure routes, i.e., soil and food for 10, 20 and 40 days. The present results revealed that the accumulation of Cu and Pb in both spiders' species increase with exposure duration and depend on the route of exposure and type of metal. The activities of CarbE, GST, and MTs significantly increased with increasing metal body burden for all experimental treatments. The CYP 450 activity exhibited a significant time-dependent decrease with increasing Cu concentration in both species. The AchE activity was significantly inhibited on Pb exposure via soil and Cu + Pb exposure via both routes. The decrease in the level of GSH was measured on Cu + Pb exposure via both routes. Thus, all these enzymatic and non-enzymatic responses are sensitive to the metals tested and could serve as early warning indicators for assessing the effects of metal pollution in these species.

Insights into the mechanisms underlying the remediation potential of earthworms in contaminated soil: A critical review of research progress and prospects

In recent years, soil pollution is a major global concern drawing worldwide attention. Earthworms can resist high concentrations of soil pollutants and play a vital role in removing them effectively. Vermiremediation, using earthworms to remove contaminants from soil or help to degrade non-recyclable chemicals, is proved to be an alternative, low-cost technology for treating contaminated soil. However, knowledge about the mechanisms and framework of the vermiremediation various organic and inorganic contaminants is still limited. Therefore, we reviewed the research progress of effects of soil contaminants on earthworms and potential of earthworm used for remediation soil contaminated with heavy metals, polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), pesticides, as well as crude oil. Especially, the possible processes, mechanisms, advantages and limitations, and how to boost the efficiency of vermiremediation are well addressed in this review. Finally, future prospects of vermiremediation soil contamination are listed to promote further studies and application of vermiremediation in contaminated soils.

Mechanism underlying earthworm on the remediation of cadmium-contaminated soil

Cadmium (Cd) contamination of soil becomes a potential agricultural and global environmental problem due to the need to ensure safe food. In this study, earthworms (Eisenia fetida) and plants (vetiver grass) were prepared for removal Cd from soil. The results showed the Cd concentration in the soil of all experimental groups decreased, notably by 17.60% in the group with 20 mg/kg Cd concentration. In the roots of vetiver, the content of Cd increased by 57% after earthworms were added and the transfer coefficient of Cd was also significantly increased. Moreover, Cd in the soil was generally absorbed by the intestinal tract of earthworms and became concentrated, mainly in the midgut and hindgut accounting for >77.78% of the total. In addition, enteric microorganism analysis demonstrated that the bacterial community structure played an important role in Cd enrichment and metabolism regulation. There was a significant correlation between some bacteria and Cd concentration. Among these bacteria, Pseudomonas brenneri, were involved in the adsorption and metabolism of Cd to reduce the toxicity of Cd to the earthworms. On the other hand, in order to cope with the external Cd stress, the malondialdehyde (MDA) and hydrogen critically (CAT) enzymes in the earthworms increased with the concentration. Therefore, the high tolerance of earthworms to Cd is related to its physiological adjustment and the balance of intestinal bacteria. The combination of earthworms, microorganisms and plants can result a good alternative to diminish the impact of Cd in soils.

Biochemical and reproductive effects of red mud to earthworm Eisenia fetida

Red mud (RM) is the main waste of alumina production whose disposal poses a problem. The research of various possible effects of red mud on soil organisms has been scarce. We have exposed earthworms (Eisenia fetida) to red mud: artificial soil mixtures. The tested samples of red mud were of different origin: Croatian (CRRM) and Hungarian (HURM). The effects of exposure on the metabolic and oxidative status of earthworms were measured using several biochemical biomarkers (acetylcholinesterase, catalase and glutathione S-transferase activity and metallothionenin content) and reproductive success was assessed upon counting the number of hatched juveniles. The LC₅₀ value for CRRM was 40% and for HURM 62% of red mud in the growth medium on weight basis, respectively. A significant effect (p < 0.001) of the RM concentration and origin, as well as significant interactions between the origin of RM and the applied concentrations on all measured biomarkers were observed. CRRM had a higher content of different metals as well as a higher conductivity in comparison to HURM. The reproduction was inhibited after exposure to both RMs. Namely, 25% CRRM caused a 53.26% reduction in the number of juveniles, whereas 18% HURM caused a 68.84% reduction, and 50% HURM caused 97.9% reduction, respectively. Both RMs caused changes in the measured biomarkers related to an oxidative stress. Consequently, the possible adverse effects on soil organisms before the environmental application of red mud should be assessed to avoid further environmental damage.

Oxidative stress responses of two different ecophysiological species of earthworms (Eutyphoeus waltoni and Eisenia fetida) exposed to Cd-contaminated soil

The aim of this study was to assess the biomarkers of oxidative stress [reduced glutathione (GSH), glutathione-S-transferase (GST), superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), glutathione reductase (GR), aldehyde dehydrogenase (ALDH) and lipid peroxidation (LPO)] in earthworms of different ecological categories [epigeic Eisenia fetida (E. fetida) and anecic Eutyphoeus waltoni (E. waltoni)] exposed to cadmium (Cd)-polluted soil (30, 60 and 120 mg kg^-1) for 28 days. Cd accumulation in earthworms increased significantly with increasing exposure dose and duration. However, E. fetida showed a relatively higher level of Cd accumulation until day 21; thereafter, depletion in the Cd level was recorded for the highest exposure dose. In E. waltoni, the detoxification enzymes and GSH level increased significantly with increasing exposure dose and Cd accumulation for 14 days (acute phase). In contrast, in E. fetida, acute exposure to Cd increased detoxification enzymes with decrease in GSH levels. For both species, sub-chronic exposures (28 days) increased lipid peroxidation with decrease in detoxification enzymes. GPx and ALDH responses of Cd-exposed earthworms showed a similar trend. Thus, these enzymes can be used as general biomarkers in these two species. The consistent variations in GST, GPx and ALDH activities suggest that E. waltoni may be used as a bioindicator species; this further signifies the use of endemic earthworms as a bioindicator to assess the risk of soil contamination. The present investigation indicates that Cd accumulation and biomarker responses in earthworms depend on dose and duration of exposure and on the concerned species.

Antioxidant responses in the earthworm Aporrectodea caliginosa of eastern Slovakia: application of principal component analysis as a tool to identify metal contaminated areas

The soil of Slovak Republic is severely contaminated with heavy metals, creating hazards to soil health. In order to assess the current status with the prospect of selecting the appropriate treatment methods and land use, this investigation aimed to determine a panel of complementary and ecologically relevant biomarkers that reflect adverse biological responses towards terrestrial pollutants. To attain this objective, the concentration of reduced glutathione and enzymes of glutathione antioxidant system were assessed in clitellate earthworm, Aporrectodea caliginosa sampled from selected sites of eastern Slovakia along with the pH and total metal concentration (As, Cd, Pb, Cr, Hg, Mn, Fe, Co, Ni, Cu, Zn) of soils. Positive, significant (p < 0.05) induction of glutathione peroxidase, glutathione reductase, and glutathione-S-transferase activities and depletion of reduced glutathione level (negative correlation) were associated with the increased soil metal concentrations. Metal interference was found in the detoxification process and antioxidant defense mechanism does not efficiently counteract the oxidative stress induced by chronic metal exposure. The tested biomarkers confirmed sensitive and affective response to the pollution of soil contaminants, in this case metals. This has a potential use in ecotoxicological field monitoring. The proposed principal component analysis is a multivariate model of data analysis that represents a cost-effective approach to differentiate metalliferous soils of eastern Slovakia with different health status.

Vermicomposting of coal fly ash using epigeic and epi-endogeic earthworm species: nutrient dynamics and metal remediation

Study highlights the metal removal efficiency and nutrient dynamics of three potent earthworm species from coal fly ash with a comparative aspect.

Exploring metal detoxification and accumulation potential during vermicomposting of Tea factory coal ash: sequential extraction and fluorescence probe analysis

Metal contamination from coal ashes (CAs) is widely recognized as a significant environmental concern. To learn more about metal detoxification and accumulation potential of earthworm species, metal-rich tea factory coal ashes (TFCA) were fed to Eisenia fetida and Lampito mauritii by employing a fluorescent tag detection method. Fascinatingly, on feeding fluorescence probed Zn and Cd along with cow dung to Eisenia fetida, the detection of the gut-proteins with a molecular mass higher than 100 kDa was a distinct evidence of metal binding. Significant increases were observed in the content of humified organic C [humic acid (HAC) and fulvic acid C (FAC)] and degree of humification during vermicomposting. Concurrently, considerably large amount of toxic metals (Cr, Cd, Pb, and Zn) was transformed from exchangeable to recalcitrant (organic matter and mineral bound) fractions. Moreover, total metal concentrations were reduced with high removal efficiency upon vermicomposting.

Cadmium transfer and detoxification mechanisms in a soil-mulberry-silkworm system: phytoremediation potential

Phytoremediation has been proven to be an environmentally sound alternative for the recovery of contaminated soils, and the economic profit that comes along with the process might stimulate its field use. This study investigated cadmium (Cd) transfer and detoxification mechanisms in a soil-mulberry-silkworm system to estimate the suitability of the mulberry and silkworm as an alternative method for the remediation of Cd-polluted soil; it also explored the underlying mechanisms regulating the trophic transfer of Cd. The results show that both the mulberry and silkworm have high Cd tolerance. The transfer factor suggests that the mulberry has high potential for Cd extraction from polluted soil. The subcellular distribution and chemical forms of Cd in mulberry leaves show that cell wall deposition and vacuolar compartmentalization play important role in Cd tolerance. In the presence of increasing Cd concentrations in silkworm food, detoxification mechanisms (excretion and homeostasis) were activated so that excess Cd was excreted in fecal balls, and metallothionein levels in the mid-gut, the posterior of the silk gland, and the fat body of silkworms were enhanced. And, the Cd concentrations in silk are at a low level, ranging from 0.02 to 0.21 mg kg(-1). Therefore, these mechanisms of detoxification can regulate Cd trophic transfer, and mulberry planting and silkworm breeding has high phytoremediation potential for Cd-contaminated soil.

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.

Dual-channel detection of metallothioneins and mercury based on a mercury-mediated aptamer beacon using thymidine-mercury-thymidine complex as a quencher

A novel dual-channel strategy for the detection of metallothioneins (MTs) and Hg(2+) has been developed based on a mercury-mediated aptamer beacon (MAB) using thymidine-mercury-thymidine complex as a quencher for the first time. In the presence of Hg(2+), the T-rich oligonucleotide with a 6-carboxyfluorescein (TRO-FAM) can form an aptamer beacon via the formation of T-Hg(2+)-T base pairs, which results in a fluorescence quenching of the sensing system owing to the fluorescence resonance energy transfer (FRET) from the fluorophore of FAM to the terminated T-Hg(2+)-T base pair. The addition of MTs into this solution leads to the disruption of the T-Hg(2+)-T complex, resulting in an increase of the fluorescent signal of the system. In the optimizing condition, ΔF was directly proportional to the concentrations ranging from 5.63 nM to 0.275 μM for MTs, and 14.2 nM to 0.30 μM for Hg(2+) with the detection limits of 1.69 nM and 4.28 nM, respectively. The proposed dual-channel method avoids the label steps of a quencher in common molecular beacon strategies, without tedious procedure or the requirement of sophisticated equipment, and is rapid, inexpensive and sensitive.

Lead in the soil-mulberry (Morus alba L.)-silkworm (Bombyx mori) food chain: translocation and detoxification

The translocation of lead (Pb) in the soil-mulberry-silkworm food chain and the process of Pb detoxification in the mulberry-silkworm chain were investigated. The amount of Pb in mulberry, silkworm, feces and silk increased in a dose-responsive manner to the Pb contents in the soils. Mulberry roots sequestered most of the Pb, ranging from 230.78 to 1209.25 mg kg(-1). Over 92% of the Pb in the mulberry leaves was deposited in the cell wall, and 95.29-95.57% of the Pb in the mulberry leaves was integrated with oxalic acid, pectates and protein, and it had low bioavailability. The Pb concentrations in the silkworm feces were 4.50-4.64 times higher than those in the leaves. The synthesis of metallothioneins in three tissues of the silkworms was induced to achieve Pb homeostasis under Pb stress. These results indicated the mechanism involved in Pb transfer along the food chain was controlled by the detoxification of Pb in different trophic levels. Planting mulberry and rearing silkworm could be a promising approach for the remediation of Pb-polluted soils due to the Pb tolerance of mulberry and silkworm.

Effects of lead on tolerance, bioaccumulation, and antioxidative defense system of green algae, Cladophora

Effects of various concentrations (0.5, 1.0, 2.5, 5.0, 7.5, and 10.0 mg/L) of lead (Pb(2+)) on the growth, bioaccumulation, and antioxidative defense system of green algae, Cladophora, was investigated. Low concentrations of Pb(2+) accelerated Cladophora growth, but concentrations of 10.0 mg/L and above inhibited the growth because of the hinderance to photosynthesis. The total soluble sugar content of Cladophora was affected by Pb(2+) treatment, but the protein content showed no significant changes. The malondialdehyde (MDA) content and peroxidase(POD) activity of Cladophora gradually increased whereas superoxide dismutase(SOD) decreased with Pb(2+) concentrations. Catalase (CAT) activity exhibited no significant changes following Pb(2+) treatment. Pb(2+) accumulated in Cladophora and that the lead content in Cladophora was correlated with POD growth, MDA, and Metallothionein (MT). POD and MT play a role in the survival of Cladophora in Pb-contaminated environments. This study suggests that Cladophora can be a choice organism for the phytoremediation of Pb-polluted coastal areas.

Metallothionein gene expression differs in earthworm populations with different exposure history

Metals are persistent pollutants in soils that can harm soil organisms and decrease species diversity. Animals can cope with metal contamination with the help of metallothioneins, small metal-binding proteins involved in homeostasis and detoxification of metals. We studied the expression of metallothionein with qPCR in a small, epigeic earthworm, Dendrobaena octaedra. We compared expression patterns and metal body content in earthworms collected from two sites with different metal contamination histories: Harjavalta, contaminated by a Cu-Ni smelter operational for over 50 years, and Jyväskylä, an uncontaminated site. Earthworms from both sites were also experimentally exposed to different concentrations of Cu (control, 50, 100 or 200 mg/kg) or Zn (control, 75, 150 or 300 mg/kg) for 7, 14 or 28 days to determine if there is a time related dose-response in gene expression. Population comparison showed that metallothionein expression was higher in earthworms from the contaminated site. In the exposure experiment, exposure time affected expression, but only in the earthworms from the uncontaminated site, suggesting that there is a delay in the metallothionein response of earthworms in this population. In contrast, earthworms from the contaminated site showed higher and constant levels of metallothionein expression at all exposure concentrations and durations. The constant metallothionein expression in earthworms from the contaminated site suggests that inducibility of metallothionein response could be lost in earthworms with metal exposure history. Adaptation of D. octaedra to metal exposure could explain the differences between the populations and explain the persistence of this species in contaminated forest soils.

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.

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.

Resonance light scattering determination of metallothioneins using levofloxacin-palladium complex as a light scattering probe

A novel method of resonance light scattering (RLS) was developed for the analysis of trace metallothioneins (MTs) in human urine. In a CH(3)COOH-CH(3)COONa buffer solution of pH 4.5, the formation of a complex between levofloxacin (LEV)-Pd and MTs led to enhance the RLS intensity of the system, and the enhanced RLS intensity at 468 nm was proportional to the concentration of MTs in the range of 0.059-22.4 μg mL(-1). The linear regression equation was ΔI=127.5 ρ (μg mL(-1))-88.02 with a correlation coefficient of 0.9992, and the detection limit of 17.8 ng mL(-1). The relative standard deviation and the average recovery were 3.8-5.4% (n=11) and 92.15%, respectively. The proposed method is convenient, reliable and sensitive, and has been used successfully for the determination of trace MTs in human urine samples.

Quantitative immunodetection of metallothioneins in relation to metals concentration in spiders from variously polluted areas

Spiders inhabiting post industrial environments, such as waste heaps or ore-bearing areas, are exposed to high concentrations of metals, accumulated in the body of their prey and transferred along food chains. Therefore spiders are pressed to develop metal-neutralization strategies. Low-molecular, multifunction proteins: metallothioneins (MTs), often postulated as biomarkers of metal exposure, are known to bind metals and thus protect organisms against their toxic effects. Yet the proteins are still not well recognized in spiders. The aim of this study was to assess, by immunodetection method, ELISA, the concentration of metallothioneins in adult females of three web building spider species: Araneus diadematus (Araneidae), Agelena labyrinthica (Agelenidae) and Linyphia triangularis (Linyphiidae) from three variously polluted areas in southern Poland: Olkusz, ore-bearing post industrial site; Katowice-WeŁnowiec: post metallurgic waste heap, Pilica: the reference, rural, area. The concentration of metallothioneins has been analyzed in relation to the metal concentration in spiders body. The study gives the evidence that metallothioneins are reliably detectable by means of ELISA technique. The analysis of results obtained shows a strong species-dependence of the MTs level. Positive correlations between MTs concentration and metal body burden (mainly Zn and Pb) were found. This suggests that the proteins play an important role in the neutralization and regulation of metal ions in spiders. The same correlation indicate the possibility to consider MTs in spiders as biomarkers of metal exposure and effects. However, the species specificity as well as metal characteristics should be taken under account.