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PubMed2004

The environmental safety of eprinomectin to earthworms.

A study was conducted to assess the environmental safety of the endectocide eprinomectin to the earthworm Lumbricus terrestris under conditions mimicking typical product use on pasture. The LC50 value of eprinomectin in artificial soil after 28 days of exposure is higher than the levels expected in feces from dosed cattle or in soil fertilized with manure from dosed cattle, which indicates a wide margin of safety for this compound to earthworms. However, the no-observed-effect concentration has not been established. Therefore, the current study was conducted to determine whether there would be any effects on earthworms from feces from cattle treated with the commercial formulation of eprinomectin. Feces were collected rectally from grazing cattle on Day 0 before treatment and on Days 2, 4, 7 and 14 after treatment with EPRINEX (eprinomectin) Pour-On for Beef and Dairy Cattle (Merial Limited) at 0.5 mg eprinomectin per kg bodyweight. Assays of eprinomectin B1a (the major component of eprinomectin) were 0, 0.427, 0.152, 0.0512 and 0.00185 mg kg-1 wet weight of feces (equivalent to 0, 3.34, 1.19, 0.40 and 0.010 mg kg-1 on a dry weight basis, respectively). No significant differences (p>0.05) were observed at any day post-treatment in the survival or behavioral effects of any worms fed post-dose feces relative to the worms fed control feces. All post-dose comparisons of weight changes of living earthworms to the control group were not significantly different (p>0.05), indicating that treatment of cattle with EPRINEX (eprinomectin) Pour-On for Beef and Dairy Cattle did not affect feeding or weight gain of the earthworms. The LC50 value and the results of this study establish the wide margin of safety afforded to earthworms by eprinomectin under typical usage conditions.

Administration, Topical↗

PubMed1998

Identification of heavy metal induced changes in the expression patterns of the translationally controlled tumour protein (TCTP) in the earthworm Lumbricus rubellus1.

Heavy metal contaminated soils are assessed for specific human health and ecological risk by governmental regulatory agencies utilizing the abundant soil invertebrate, the earthworm, in a biomonitoring process. Fingerprinting the molecular genetic responses resulting from heavy metal exposure facilitates the identification of biomarkers for assessing the impact of such pollution on individual organisms. This paper reports the identification of a novel translationally controlled tumour protein (TCTP) in the earthworm Lumbricus rubellus. In addition to the standard molecular biological technique of differential Southern blotting, a fully quantitative approach (fluorescent microvolume PCR) was performed to assess the specific expression profiles of TCTP in earthworms exposed to different heavy metal regimes. After normalizing with actin as an invariant control, the results showed that TCTP was upregulated by at least a factor of 4 in the population originating from a Pb/Zn/Cd polluted mine, compared to an unpolluted control population. An even more pronounced increase was identified in earthworms native to a Cu polluted mine, where TCTP increased 335-fold. TCTP copies in earthworms exposed to artificial soil with a single stressor (Cd) were 14 times higher than in the appropriate control earthworms (maintained on artificial soil without Cd). The data presented are novel in two ways: first, they provide evidence for an upregulation that is induced by heavy metals (especially copper); second, they show that TCTP can also be under transcriptional control, therefore upregulation is not limited to translational modifications as TCTP's nomenclature suggests.

Amino Acid Sequence↗

PubMed1998

The distribution and intracellular compartmentation of metals in the endogeic earthworm Aporrectodea caliginosa sampled from an unpolluted and a metal-contaminated site.

The tissue distribution of Cd, Cu, Pb, Zn and Ca in the endogeic earthworm Aporrectodea caliginosa living in a non-polluted and a heavy metal polluted soil was investigated. The tissues of animals from the contaminated soil contained greater concentrations of Cd, Pb and Zn than the corresponding tissues of animals from the unpolluted soil. The greatest concentrations of Cd, Pb, Zn, and Ca were primarily accumulated within the posterior alimentary canal (PAC), a tissue fraction which contained the greatest proportion of the whole-worm burdens of the respective metals. Cu was distributed fairly evenly in the tissue fractions investigated. The pattern of accumulation for the 'heavy' metals is broadly similar to that for epigeic earthworms; in contrast, a different pattern of tissue accumulation was found for Ca. In animals from the uncontaminated site, the major elemental constituents of the chloragosomes were P, Ca, Zn and S. A significant positive correlation exists between P and Ca within the chloragosomal matrix. These intracellular vesicles are major foci for Pb and Zn accumulation within the PAC, with 'excess' metals associated with P ligands within the chloragosome matrix. The incorporation of Pb and Zn appears to involve the cationic displacement of Ca. Such compartmentation appears to prevent dissemination of large concentrations of these metals into other earthworm tissues, and may thus represent a detoxification strategy based on accumulative immobilization. No intracellular localization of Cd was identified in the study, although the Cd concentration in the metalliferous soils examined was not exceptionally high. The observations are discussed in the context of a contribution to enhanced understanding of metal ecotoxicology in earthworms by providing baseline data on a little investigated ecophysiological group of earthworms. Comparisons of metal distribution and mechanisms of metal sequestration are made with other ecophysiological groups of earthworms, and the significance of the findings to biomonitoring and toxicity-testing programmes is considered.

Journal Article↗

PubMed2000

Genotoxicity of two novel pesticides for the earthworm, Eisenia fetida.

In this paper, several studies were conducted to evaluate the genotoxicity of two pesticides, Imidacloprid and RH-5849, for earthworm (Eisenia fetida). Earthworms were exposed in different exposure systems to evaluate their acute toxicity and the genotoxicity of the two pesticides was evaluated by using the method of sperm deformity assessment, micronucleus test of root tip cells in Vicia faba, a mouse bone-marrow micronucleus test, and comet assay. LC(50) (interpolated concentration at which 50% mortality of test population occurs) for earthworms varied in different exposure systems. The results indicated that Imidacloprid was consistently more toxic than RH-5849 in all exposure systems. In this study, sperm deformity test was used to detect the potential adverse influences of pesticides on the reproduction of earthworms. The results demonstrated that significant induction of sperm deformity (p<0.01) and a dose-effect relationship displayed at Imidacloprid concentrations higher than 0.5 mg/kg dry soil. However, the sperm deformity frequency of groups exposed to RH-5849 did not show significant difference (p>0.05) from the control until the dose reached 100 mg/kg dry soil. The results of the V. faba micronucleus tests showed that micronuclei frequency of the exposed group did not show significant difference (p>0.05) from the control until the concentration of Imidacloprid and RH-5849 reached 100 mg/ml. The results of the mouse bone-marrow micronuclei test also indicate that two pesticides did not show significant effects (p>0.05) on the micronuclei frequency in mice bone-marrow cells until the dose reached 100 mg/kg for Imidacloprid and 300 mg/kg for RH-5849 (2/3 LD(50)). Although no genotoxicity was detected by using the micronucleus tests, the results of the comet assay showed that the two pesticides induce significant DNA damage (p<0.01) in earthworms and dose-effect relationships were displayed. The 'earthworm comet assay' is a rapid and sensitive way to screen chemicals or terrestrial environments for their DNA-damaging properties.

Journal Article↗

PubMed2003

Identification of two types of synaptic activity in the earthworm nervous system during locomotion.

In the ventral nervous system of the earthworm, a central pattern generator and motor neurons are activated during locomotion. We have previously reported that bath application of octopamine (OA) induces fictive locomotion in the earthworm, and the burst frequency of electrical activity from the first lateral nerves increases with OA concentration. However, there are no reports concerning locomotor neural networks in the earthworm. To identify neural networks involved in fictive locomotion, we optically monitored activity-dependent fluorescent staining in the earthworm ventral nerve cord (VNC) with a styryl dye, N-(3-triethylammoniumpropyl)-4-(4-(dibutylamino)styryl)pyridinium dibromide (FM1-43), and a confocal laser scanning microscope. OA induces FM1-43 fluorescence in a dose-dependent manner, with bright fluorescent spots of 3-10 microm in diameter observed to be localized around specified neurons in the segmental ganglion of the VNC. We compared OA dose-response curves for FM1-43 fluorescence with the bursting frequency for fictive locomotion, and found that two types of curves could be identified: one fluorescence response shows a similar dose-dependency to that of the burst frequency, while another response has a higher sensitivity to OA. From these results, we suggest that OA acts as one of the neuromodulators for the earthworm locomotion. This is the first attempt to record motor and inter-neuronal activities simultaneously in a locomotor network in the earthworm.

Action Potentials↗

PubMed2003

Earthworms (Oligochaeta, Lumbricidae) and mycobacteria.

The objective of the study was to define the role of earthworms in the survival of mycobacteria in animal populations. In 13 sampling sites mycobacteria were detected in 53 (5.5%) samples of faeces and parenchymatous tissues from animals, in 25 (7.3%) environmental and in nine (8.2%) earthworm samples. In cattle and goat farms affected by Mycobacterium avium subsp. paratuberculosis (M. paratuberculosis) of IS900 restriction fragment length polymorphism (RFLP) type B-C1 was isolated from 37 (4.6%) faecal samples, three (1.4%) environmental and one (3.1%) earthworm sample. Investigations of aviaries affected by avian tuberculosis detected M. avium of genotype IS901+ and IS1245+ in six (7.9%) bird's faecal and in four (4.4%) environmental samples. M. avium (genotype IS901- and IS1245+) was detected in four (4.4%) and M. abscessus in one (1.1%) environmental sample. M. avium of genotype IS901- and IS1245+ and M. gastri were isolated from three (6.4%) earthworm samples. In pig farm with mycobacteriosis M. avium of genotype IS901- and IS1245+ was detected in five (20.0%) faecal samples from pigs and in four (12.9%) environmental samples. M. scrofulaceum was isolated in one (4.6%) sample of Lumbricus rubellus. In laboratory experiments identical RFLP types of M. paratuberculosis were isolated from bodies and faeces of earthworms 1-2 days after the last contact with the faeces contaminated with the same RFLP type of M. paratuberculosis. The results suggest that earthworms may become vectors of mycobacteria.

Animals↗

PubMed2001

Bioavailability of nonextractable (bound) pesticide residues to earthworms.

There is an ongoing debate regarding whether nonextractable (bound) pesticide residues in soils are occluded or may remain bioavailable in the long term in the environment. This study investigated the release of 14C-labeled residues, which were previously nonextractable after exhaustive extraction with organic solvents in soils, and their uptake by earthworms (Aporrectodea longa). After a 100-day incubation of soils treated with 14C-labeled atrazine, isoproturon, and dicamba and exhaustive Soxhlet extractions with methanol and dichloromethane, nonextracted 14C-labeled residues remaining in the soils were 18, 70, and 67%, respectively. Adding clean soil in the ratio of 7:1 increased the volumes of these extracted soils. After earthworms had lived in these previously extracted soils for 28 days, 0.02-0.2% of previously bound 14C activity was absorbed into the earthworm tissue. Uptake by earthworms was found to be 2-10 times higher in soils containing freshly introduced 14C-labeled pesticides as compared to soils containing nonextractable 14C-labeled residues. The differential bioavailability observed between freshly introduced 14C-labeled pesticides and those previously nonextractable may be related to the ease of transfer of the 14C activity into the solution phase. By the end of the 28-day incubation period, 3, 23, and 24% of previously nonextractable 14C-labeled isoproturon, dicamba, and atrazine residues, respectively, were extracted by solvents or mineralized to 14CO2. The amounts of 14C activity released were not significantly different in the presence or in the absence of earthworms in soils containing previously nonextractable residues. However, the formation of bound residues was 2, 2, and 4 times lower for freshly introduced 14C-labeled isoproturon, dicamba, and atrazine, respectively, suggesting that the presence of earthworms retarded bound residue formation.

Animals↗

PubMed2001

Polycyclic aromatic hydrocarbon-polluted dredged peat sediments and earthworms: a mutual interference.

In lowland areas of the Netherlands, any peat sediments will gradually become enriched with anthropogenically derived Polycyclic Aromatic Hydrocarbons. Due to Dutch policy standards these (anaerobic) sediments are not allowed to be dredged and placed onto land. Under aerobic conditions, however, biodegradation of PAH is greatly enhanced. This degradation is further stimulated by colonisation of the sediments by earthworms. Laboratory experiments show that although earthworms do not avoid PAH-contaminated sediment, their burrowing-activity is reduced. Furthermore, these sediments have no significant ecotoxicological impacts on earthworms. Experimental introduction of earthworms into PAH-contaminated OECD-soil will result in a decrease in overall PAH content. In field surveys no significant differences in earthworm numbers between locations with fresh and old sediment could be found. It is concluded that dredging of PAH-contaminated sediment poses a very limited environmental threat, and that putting these sediments on land will improve PAH-biodegradation, partly through the colonisation by and activities of earthworms.

Animals↗

PubMed1986

Earthworms produce a collagen-like substance detected by the garter snake vomeronasal system.

Earthworms (Lumbricus terrestris) produce a chemical substance that is readily detected by and serves as an attractant for garter snakes (Thamnophis sirtalis). This chemoattractant is sensed by the vomeronasal system of snakes. Amino acid analysis of the chemoattractant revealed a high hydroxyproline/proline ratio and large amounts of serine and threonine. More than one-third of the residues were glycine. No hydroxylysine and no cysteine were present. Carbohydrate analyses revealed a high content of galactose (11% by weight) and smaller amounts of fucose, mannose, glucose, N-acetylglucosamine, and N-acetylgalactosamine. These results were very similar to results reported for the amino acid composition and carbohydrate content of earthworm cuticle collagen and gelatin. A preparation of purified earthworm cuticle collagen proved to be a potent source of chemoattractant for garter snakes. Further, it was not possible to prepare chemoattractant from decuticlized earthworms. These results strongly suggest that a component of the earthworm chemoattractant for snakes is structurally related to earthworm cuticle collagen.

Animals↗

PubMed2000

Sorption of atrazine and metolachlor by earthworm surface castings and soil.

Atrazine and metolachlor were more strongly retained on earthworm (Lumbricus terrestris L.) castings than on soil, suggesting that earthworm castings at the surface or at depth can reduce herbicide movement in soil. Herbicide sorption by castings was related to the food source available to the earthworms. Both atrazine and metolachlor sorption increased with increasing organic carbon (C) content in castings, and Freundlich constants (Kf values) generally decreased in the order: soybean-fed > corn-fed > not-fed-earthworm-castings. The amount of atrazine or metolachlor sorbed per unit organic carbon (Koc values) was significantly greater for corn-castings compared with other castings, or soil, suggesting that the composition of organic matter in castings is also an important factor in determining the retention of herbicides in soils. Herbicide desorption was dependent on both the initial herbicide concentration, and the type of absorbent. At small equilibrium herbicide concentrations, atrazine desorption was significantly greater from soil than from any of the three casting treatments. At large equilibrium herbicide concentrations, however, the greater organic C content in castings had no significant effect on atrazine desorption, relative to soil. For metolachlor, regardless of the equilibrium herbicide concentration, desorption from soybean- and corn-castings treatments was always less than desorption from soil and not-fed earthworm castings treatments. The results of this study indicate that, under field conditions, the extent of herbicide retention on earthworm castings will tend to be related to crop and crop residue management practices.

Acetamides↗

PubMed2003

The fate of 14C-diazinon in compost, compost-amended soil, and uptake by earthworms.

A process for disposing of pesticide rinsates using sorption onto organic matter followed by composting is being evaluated. As a part of this evaluation process, we have studied the bioavailability of composted delta-2-14C-diazinon and its degradation products to earthworms (Eisenia foetida Savigny) in 30 and 60 d compost amended soil. After 60 d of composting there was considerable degradation of diazinon (95%) and a corresponding increase in the primary hydrolysis product, 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMHP) as determined by high performance thin layer chromatography (HPTLC). Approximately 50% of the radioactivity became incorporated into the non-extractable fractions associated with composted organic matter with no measurable amounts of 14CO2 produced during the 60-day composting period. Following addition of the composted materials to soil, diazinon leading to 50% mortality after 14 d of exposure; continued to slowly degrade and become increasingly sorbed/entrapped within the soil-compost matrix. Soil amended with 30-d composted diazinon was toxic to earthworms whereas, no mortality was observed in those earthworms exposed to the 60-d composted diazinon. However, earthworms exposed to 30-d and 60-d composted diazinon were found to have similar levels of radioactivity in their tissues. The majority of the radioactivity in earthworms exposed 60-d composted diazinon was either unextractably bound within the earthworm tissue or was not acetone soluble. Most of the radioactivity that could be extracted with acetone was not separated by the two HPTLC methods we used. This study demonstrates that composting high concentrations of diazinon can greatly reduce toxicity and the amount of diazinon that is bioavailable to a representative soil macroinvertebrate (E. foetida).

Animals↗

PubMed2005

Influence of soil properties on bioaccumulation of 14C-simazine in earthworms Eisenia foetida.

The toxicity of pesticides has been evaluated by several methods including tests with earthworms in both artificial and natural soils treated with the compounds. The ecological niches of earthworms make them good bioindicators of soil contamination. The bioaccumulation of 14C-simazine (6-chloro-N2-N4-diethyl- 1,3,5-triazine-2,4-diamine) was evaluated in earthworms (Eisenia foetida) maintained during three months in two substrates with different physical-chemical characteristics. The substrates were treated with 3.0 mg and 330 kBq of 14C-simazine kg(-1) substrate. Results indicated that worms did not influence simazine dissipation in both substrates as indicated by similar recoveries and with no statistical differences with and without earthworms. The radiocarbon recoveries were 86.8 and 95.3%, respectively in the substrates with lower and higher organic matter contents with earthworms, and 91.0 and 107.4% in the same substrates without worms. However, in earthworms the recoveries were statistically higher when they were maintained in the substrate with lower amount of organic matter (0.89%) than from the higher one (0.33%). Consequently, 14C-simazine bioconcentration factor (BCF) was also greater in the substrate with lower organic matter (6.89+/-1.55) than in the substrate with higher organic matter content (0.88+/-0.06). The results suggest that the higher soil organic matter content will cause lower probability of contamination of soil organisms with simazine.

Animals↗

PubMed1996

Influence of earthworm activity on gene transfer from Pseudomonas fluorescens to indigenous soil bacteria.

We have developed a model system to assess the influence of earthworm activity on the transfer of plasmid pJP4 from an inoculated donor bacterium, Pseudomonas fluorescens C5t (pJP4), to indigenous soil microorganisms. Three different earthworm species (Lumbricus terrestris, Lumbricus rubellus, and Aporrectodea trapezoides), each with unique burrowing, casting, and feeding behaviors, were evaluated. Soil columns were inoculated on the surface with 10(8) cells per g of soil of the donor bacterium, and after a 2-week incubation period, donor, transconjugant, and total bacteria were enumerated at 5-cm-depth intervals. Transconjugants were confirmed by use of colony hybridization with a mer gene probe. In situ gene transfer of plasmid pJP4 from P. fluorescens C5t to indigenous soil bacteria was detected in all inoculated microcosms. In the absence of earthworms, the depth of recovery was limited to the top 5 cm of the column, with approximately 10(3) transconjugants per g of soil. However, the total number of transconjugants recovered from soil was significantly greater in microcosms containing either L. rubellus or A. trapezoides, with levels reaching about 10(5) CFU/g of soil. In addition, earthworms distributed donor and transconjugant bacteria throughout the microcosm columns, with the depth of recovery dependent on the burrowing behavior of each earthworm species. Donor and transconjugant bacteria were also recovered from earthworm casts and inside developing cocoons. Transconjugant bacteria from the indigenous soil microflora were classified as belonging to Acidovorax spp., Acinetobacter spp., Agrobacterium spp., Pasteurella spp., Pseudomonas spp., and Xanthomonas spp.

Animals↗

PubMed2003

N2O-producing microorganisms in the gut of the earthworm Aporrectodea caliginosa are indicative of ingested soil bacteria.

The main objectives of this study were (i) to determine if gut wall-associated microorganisms are responsible for the capacity of earthworms to emit nitrous oxide (N(2)O) and (ii) to characterize the N(2)O-producing bacteria of the earthworm gut. The production of N(2)O in the gut of garden soil earthworms (Aporrectodea caliginosa) was mostly associated with the gut contents rather than the gut wall. Under anoxic conditions, nitrite and N(2)O were transient products when supplemental nitrate was reduced to N(2) by gut content homogenates. In contrast, nitrite and N(2)O were essentially not produced by nitrate-supplemented soil homogenates. The most probable numbers of fermentative anaerobes and microbes that used nitrate as a terminal electron acceptor were approximately 2 orders of magnitude higher in the earthworm gut than in the soil from which the earthworms originated. The fermentative anaerobes in the gut and soil displayed similar physiological functionalities. A total of 136 N(2)O-producing isolates that reduced either nitrate or nitrite were obtained from high serial dilutions of gut homogenates. Of the 25 representative N(2)O-producing isolates that were chosen for characterization, 22 isolates exhibited >99% 16S rRNA gene sequence similarity with their closest cultured relatives, which in most cases was a soil bacterium, most isolates were affiliated with the gamma subclass of the class Proteobacteria or with the gram-positive bacteria with low DNA G+C contents, and 5 isolates were denitrifiers and reduced nitrate to N(2)O or N(2). The initial N(2)O production rates of denitrifiers were 1 to 2 orders of magnitude greater than those of the nondenitrifying isolates. However, most nondenitrifying nitrate dissimilators produced nitrite and might therefore indirectly stimulate the production of N(2)O via nitrite-utilizing denitrifiers in the gut. The results of this study suggest that most of the N(2)O emitted by earthworms is due to the activation of ingested denitrifiers and other nitrate-dissimilating bacteria in the gut lumen.

Animals↗

PubMed2003

The earthworm gut: an ideal habitat for ingested N2O-producing microorganisms.

The in vivo production of nitrous oxide (N(2)O) by earthworms is due to their gut microbiota, and it is hypothesized that the microenvironment of the gut activates ingested N(2)O-producing soil bacteria. In situ measurement of N(2)O and O(2) with microsensors demonstrated that the earthworm gut is anoxic and the site of N(2)O production. The gut had a pH of 6.9 and an average water content of approximately 50%. The water content within the gut decreased from the anterior end to the posterior end. In contrast, the concentration of N(2)O increased from the anterior end to the mid-gut region and then decreased along the posterior part of the gut. Compared to the soil in which worms lived and fed, the gut of the earthworm was highly enriched in total carbon, organic carbon, and total nitrogen and had a C/N ratio of 7 (compared to a C/N ratio of 12 in soil). The aqueous phase of gut contents contained up to 80 mM glucose and numerous compounds that were indicative of anaerobic metabolism, including up to 9 mM formate, 8 mM acetate, 3 mM lactate, and 2 mM succinate. Compared to the soil contents, nitrite and ammonium were enriched in the gut up to 10- and 100-fold, respectively. The production of N(2)O by soil was induced when the gut environment was simulated in anoxic microcosms for 24 h (the approximate time for passage of soil through the earthworm). Anoxia, high osmolarity, nitrite, and nitrate were the dominant factors that stimulated the production of N(2)O. Supplemental organic carbon had a very minimal stimulatory effect on the production of N(2)O, and addition of buffer or ammonium had essentially no effect on the initial N(2)O production rates. However, a combination of supplements yielded rates greater than that obtained mathematically for single supplements, suggesting that the maximum rates observed were due to synergistic effects of supplements. Collectively, these results indicate that the special microenvironment of the earthworm gut is ideally suited for N(2)O-producing bacteria and support the hypothesis that the in situ conditions of the earthworm gut activate ingested N(2)O-producing soil bacteria during gut passage.

Animals↗

PubMed2006

In vivo emission of dinitrogen by earthworms via denitrifying bacteria in the gut.

Earthworms emit the greenhouse gas nitrous oxide (N2O), and ingested denitrifiers in the gut appear to be the main source of this N2O. The primary goal of this study was to determine if earthworms also emit dinitrogen (N2), the end product of complete denitrification. When [15N]nitrate was injected into the gut, the earthworms Aporrectodea caliginosa and Lumbricus terrestris emitted labeled N2 (and also labeled N2O) under in vivo conditions; emission of N2 by these two earthworms was relatively linear and approximated 1.2 and 6.6 nmol N2 per h per g (fresh weight), respectively. Isolated gut contents also produced [15N]nitrate-derived N2 and N2O under anoxic conditions. N2 is formed by N2O reductase, and acetylene, an inhibitor of this enzyme, inhibited the emission of [15N]nitrate-derived N2 by living earthworms. Standard gas chromatographic analysis demonstrated that the amount of N2O emitted was relatively linear during initial incubation periods and increased in response to acetylene. The calculated rates for the native emissions of N2 (i.e., without added nitrate) by A. caliginosa and L. terrestris were 1.1 and 1.5 nmol N2 per h per g (fresh weight), respectively; these emission rates approximated that of N2O. These collective observations indicate that (i) earthworms emit N2 concomitant with the emission of N2O via the in situ activity of denitrifying bacteria in the gut and (ii) N2O is quantitatively an important denitrification-derived end product under in situ conditions.

Acetylene↗

PubMed2001

Evaluation for Hsp70 as a biomarker of effect of pollutants on the earthworm Lumbricus terrestris.

Induction of heat shock proteins (Hsps) is often associated with a cellular response to a harmful stress or to adverse life conditions. The main aims of the present study were (1) to assess if stress-induced Hsp70 could be used to monitor exposure of the earthworm species Lumbricus terrestris to various soil pollutants, (2) to assess the specificity of pollutants in their tissue targeting and in Hsp70 induction, and (3) to evaluate if dose-response relationships could be established and if the stress-response observed was specific. The midgut/intestinal tissues of L. terrestris are shown to express an inducible member of the Hsp70 family after heat shock treatment in vitro and exposures to different soil toxicants in vivo (re: artificial soil). Short-term (24-72 hours) and long-term (14-16 days) exposures to the chemical standards chloroacetamide and pentachlorophenol and to heavy metals (Pb++, Cd++, Cu++, and Hg++) also affected the earthworms, and Hsp70 was induced in their midgut/intestinal tissues. After a 3-day exposure to heavy metals, the level of Hsp70 induction in the midgut/intestinal tissues appears to correlate well with the reported in vivo and in vitro toxicity data. Comparatively, in proximal and midbody wall muscle tissues of animals exposed to the heavy metals, a decrease in expression of Hsp70 was sometimes detected. Thus Hsp analysis by Western blot in L. terrestris tissues and particularly in the midgut/intestine proved to be a suitable and sensitive assay for adverse effects in earthworms and showed a good level of reproducibility despite some individual variations. The use of pristine/nonexposed animals transposed into contaminated environments as in the present study should therefore be of high ecological relevance. Induction of Hsp70 in earthworms should represent not only a good wide-spectrum biomarker of exposure but also a biomarker of effect since known toxicants altered gene expression in tissues of these animals, as contrasted with a simple accumulation of Hsp. Hence, the detection of Hsp70 in earthworms can constitute an early-warning marker for the presence of potentially deleterious agents in soils, with L. terrestris in particular and earthworms in general acting as potential sentinel animal species.

Acetamides↗

PubMed2001

Effects of endophyte status of tall fescue tissues on the earthworm (Eisenia fetida).

A cryptic fungal endophyte, Neotyphodium coenophialum, infects most tall fescue (Festuca arundinacea) pastures in the United States. Cattle, sheep, and horses that consume the endophyte-infected grass can suffer fescue toxicosis caused by toxic alkaloids in the infected plants. The effects of the endophyte on mammalian herbivores have been well documented, but less is known regarding the quality of the grass (infected vs noninfected) as a food material for soil invertebrates. We conducted 21-d tests with earthworms (Eisenia fetida) to determine the nutritional quality of endophyte-infected and noninfected tall fescue leaf and root tissues. Earthworm survival, growth, and reproduction were measured in each treatment combination of tissue type and infection status. Earthworm survival was 100% in all treatments. Tall fescue tissue type (leaf vs root) and infection status (present or absent) both significantly affected E. fetida growth and reproduction. The earthworms grew and had moderate levels of reproduction in replicates containing tall fescue leaf tissue as the sole food source regardless of the endophyte-infection status, but earthworms lost weight and had less reproduction in replicates where tall fescue root tissue was the sole food source. An unexpected effect of infection status on earthworm growth in the tall fescue leaf-tissue treatments was also evident: mean growth of E. fetida with access to endophyte-infected leaf tissue as the sole food source was 3.6-fold greater than mean growth of E. fetida with access to noninfected leaf tissue as the sole food source. Knowledge regarding the relative effects of endophyte status of tall fescue on soil organisms may allow the development of more effective environmental management strategies at sites where tall fescue is being considered for use in phytoremediation or for vegetative cover. Investigators working with tall fescue should be alert to the possibility of endophyte-mediated effects of tall fescue on other organisms and, at a minimum, should provide information regarding the grass's infection status when reporting the results of studies that involve use of tall fescue.

Animals↗