Coelomic fluid: a complimentary biological medium to assess sub-lethal endosulfan exposure using ¹H NMR-based earthworm metabolomics

Toxicity of titanate nanotubes in earthworm (Eisenia fetida): Growth inhibition and integrated biomarker response

Widely use of Titanate Nanotubes (TNTs) as remediation materials for heavy metal polluted water and soil lead to their release into the soil environment, persistently threatening faunal biodiversity and the entire environment. Growth inhibition rates (GIR) and specific growth rates (SGR) are used to evaluate the effect of TNTs on earthworm growth, and the integrated biomarker response (IBR) index is used to comprehensively evaluate the toxicity of eight biomarkers (Protein-body mass ratio, MDA, SOD, CAT, POD, Cellulase, AChE, and Na⁺/K⁺-ATPase) on earthworms exposed to TNTs contaminated soil by concentrations of CK, 50, 250, 500 and 2500 mg TNTs/kg dry soil. Results show that TNTs significantly inhibit the growth of earthworms (p < 0.05), and GIR reaches up to 52.34 % at 2500 mg TNTs/kg dry soil for 28 days. IBR index has a dose-time relationship, which indicates that exposure time and concentration of TNTs contaminated soil affect the toxicity degree of contaminant to earthworms.

Metabolite changes associated with earthworms (Eisenia fetida) graphene exposure revealed by matrix-assisted laser desorption/ionization mass spectrometry imaging

The increased production and environmental release of graphene nanoparticles has raised concerns about its environmental impact, but the effects of graphene on living organisms at the metabolic level remain unknown. In this study, we used matrix assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI)-based untargeted metabolomics to investigate the metabolic response of juvenile earthworms (Eisenia fetida) to graphene exposure in soil tests for the first time. Our results reveal that graphene-exposure significantly disturbs earthworm metabolome, and graphene toxicity on earthworm shows non-concentration-dependent effect. Alanine, phenylalanine, proline, glutamate, arginine, histidine, maltose, glucose, malate, succinate, myo-inositol, and spermidine were successfully screened as significantly change compounds in earthworms for the exposure of graphene. The heterogeneous distributions of these metabolites in earthworm were also clearly imaged by MALDI-MSI. Our MSI results fully showed that the metabolite expression levels in juvenile earthworms significantly changed (up-/down-regulation) after exposure to graphene nanoparticles. This work improves our understanding of graphene nanoparticle toxicity to juvenile earthworms and also enables the continued progression of MALDI-MSI-based metabolomics as an emerging, reliable, and rapid ecotoxicological tool for assessing contaminant toxicity.

Targeted toxicometabolomics of endosulfan sulfate in adult zebrafish (Danio rerio) using GC-MS/MS in multiple reaction monitoring mode

Endosulfan sulfate is a major oxidative metabolite of the chlorinated insecticide endosulfan. In this study, a targeted metabolomics approach was used to investigate the toxic mechanisms of endosulfan sulfate in adult zebrafish using the multiple reaction monitoring mode of a GC-MS/MS. The LC₅₀ of endosulfan sulfate in adult zebrafish was determined and then zebrafish were exposed to endosulfan sulfate at one-tenth the LC₅₀ (0.1LC₅₀) or the LC₅₀ for 24 and 48 h. After exposure, the fish were extracted, derivatized and analyzed by GC-MS/MS for 379 metabolites to identify 170 metabolites. Three experimental groups (control, 0.1LC₅₀ and LC₅₀) were clearly separated in PLS-DA score plots. Based on the VIP, ANOVA, and fold change results, 40 metabolites were selected as biomarkers. Metabolic pathways associated with those metabolites were identified using MetaboAnalyst 4.0 as follows: aminoacyl-tRNA biosynthesis, valine/leucine/isoleucine biosynthesis, citrate cycle, glycerolipid metabolism, and arginine/proline metabolism. Gene expression studies confirmed the activation of citrate cycle and glycerolipids metabolism. MDA levels of the exposed group significantly increased in oxidative toxicity assay tests. Such significant perturbations of important metabolites within key biochemical pathways must result in biologically hazardous effects in zebrafish.

Evaluating the effects of the tebuconazole on the earthworm, Eisenia fetida by H-1 NMR-Based untargeted metabolomics and mRNA assay

Tebuconazole, a widely used fungicide, can severely disrupt the reproductive process of various organisms. In this study, we investigated the subacute effects of tebuconazole on the earthworm to fully understand its toxic implications. Herein, untargeted metabolomics, mRNA assay and biochemical approaches were adopted to evaluate the subacute effects of Eisenia fetida earthworms, when exposed to tebuconazole at three different concentrations (0.5, 5 and 50 mg/kg) for seven days. SOD enzyme activity test displayed that tebuconazole exposure interfered with the earthworms' ROS. ANN mRNA expression was down-regulated after tebuconazole exposure. ¹H nuclear magnetic resonance (¹H-NMR)-based untargeted metabolomics study showed that 5 mg/kg tebuconazole exposure interfered with earthworms' metabolism. Twelve significantly changed metabolites were identified. The pathway analyses indicate that tebuconazole can disrupt the earthworm's metabolism, particularly in the AMP pathway, which impact the reproduction. This may explain the tebuconazole's mechanism of action behind the down-regulation of the expression of ANN mRNA, which is related to the earthworm's reproductive process. We comprehensively evaluated the mRNA expression, enzyme activity, and metabolomics, and acquired sufficient information for evaluating the toxicity of tebuconazole.

Selection of an optimal culture medium and the most responsive viability assay to assess AgNPs toxicity with primary cultures of Eisenia fetida coelomocytes

Earthworm immune cells (coelomocytes) have become a target system in ecotoxicology due to their sensitivity against a wide range of pollutants, including silver nanoparticles (AgNPs). Presently, in vitro approaches (viability assays in microplate, flow cytometry, cell sorting) with primary cultures of Eisenia fetida coelomocytes have been successfully used to test the toxicity and the dissimilar response of cell subpopulations (amoebocytes and eleocytes) after PVP-PEI coated AgNPs and AgNO₃ exposures. In order to obtain reliable data and to accurately assess toxicity with coelomocytes, first an optimal culture medium and the most responsive assay were determined. AgNPs posed a gradual decrease in coelomocytes viability, establishing the LC₅₀ value in RPMI-1640 medium at 6 mg/l and discarding that the observed cytotoxicity was attributable to its coating agent PVP-PEI. Exposure to AgNPs caused selective cytotoxicity in amoebocytes, which correlated with the Ag concentrations measured in sorted amoebocytes and reinforced the idea of dissimilar sensitivities among amoebocytes and eleocytes. Silver nano and ionic forms exerted similar toxicity in coelomocytes. The in vitro approaches with coelomocytes of E. fetida performed in this study have the capacity to predict impairments caused by pollutants at longer exposure levels and thus, provide rapid and valuable information for eco(nano)toxicology.

Metabolite biomarkers of chlorothalonil exposure in earthworms, coelomic fluid, and coelomocytes

Earthworm (Eisenia fetida) metabolomics is a useful indicator of toxicant exposure. Extracts of whole earthworms are most commonly used to measure metabolic perturbations, in addition to coelomic fluid which has been used on a more limited basis. Coelomocytes are free moving cells found within earthworm coelomic fluid, and the potential of this compartment has not been evaluated for its utility in earthworm metabolomics. In this study, earthworms were exposed to 18.5 and 37.0 mg/kg chlorothalonil, a commonly used fungicide that targets glutathione. The metabolic impacts of a 14-day chlorothalonil exposure were assessed using ¹H NMR and targeted LC-MS measurements of earthworm, coelomic fluid, and coelomocyte extracts. Coelomic fluid was identified as the most sensitive matrix for measuring the effects of chlorothalonil exposure, where an increase in glutamine levels was the only biomarker observed at both doses. At the high dose, multiblocked-orthogonal partial least squares-discriminant analysis (MB-OPLS-DA) supported increased N-acetylserine and ophthalmic acid levels as additional biomarkers of exposure in coelomic fluid. These perturbations may indicate increased oxidative stress, although no changes in glutathione were observed in any matrix.

Comparison of metabolomic responses of earthworms to sub-lethal imidacloprid exposure in contact and soil tests

Eisenia fetida earthworms were exposed to sub-lethal levels of imidacloprid for 48 h via contact filter paper tests and soil tests. After the exposure, ¹H nuclear magnetic resonance (NMR) metabolomics was used to measure earthworm sub-lethal responses by analyzing the changes in the polar metabolite profile. Maltose, glucose, malate, lactate/threonine, myo-inositol, glutamate, arginine, lysine, tyrosine, leucine, and phenylalanine relative concentrations were altered with imidacloprid exposure in soil. In addition to these metabolites (excluding leucine and phenylalanine), fumarate, ATP, inosine, betaine, scyllo-inositol, glutamine, valine, tryptophan, alanine, tyrosine, and isoleucine relative concentrations shifted with imidacloprid exposure during contact tests. Metabolite changes in E. fetida earthworms exposed to imidacloprid showed a non-linear concentration response and an upregulation in gluconeogenesis. Overall, imidacloprid exposure in soil induces a less pronounced response in metabolites glucose, maltose, fumarate, adenosine-5'-triphosphate (ATP), inosine, scyllo-inositol, lactate/threonine, and tyrosine in comparison to the response observed via contact tests. Thus, our study highlights that tests in soil can result in a different metabolic response in E. fetida and demonstrates the importance of different modes of exposure and the extent of metabolic perturbation in earthworms. Our study also emphasizes the underlying metabolic disruption of earthworms after acute sub-lethal exposure to imidacloprid. These observations should be further examined in different soil types to assess the sub-lethal toxicity of imidacloprid to soil-dwelling earthworms.

Effects of the Chiral Fungicides Metalaxyl and Metalaxyl-M on the Earthworm Eisenia fetida as Determined by ¹H-NMR-Based Untargeted Metabolomics

Although metalaxyl and metalaxyl-M are widely used fungicides, very little is known about their subacute and enantiospecific effects on the earthworm metabolome. In this study, Eisenia fetida were exposed to metalaxyl and metalaxyl-M at three concentrations (0.5, 5 and 50 mg/kg) for seven days. ¹H nuclear magnetic resonance (¹H-NMR)-based untargeted metabolomics showed that metalaxyl and metalaxyl-M exposure disturbed earthworms’ metabolism at all three concentrations. Endogenous metabolites, such as succinate, arginine, aspartate, urea, asparagine, alanine, trimethylamine, taurine, cysteine, serine, threonine, histidine, lysine, glucose, choline, carnitine, citric acid, alpha-ketoisovaleric acid, fumaric acid and so on, were significantly changed. These results indicate that metalaxyl and metalaxyl-M produce different, enantiospecific disturbances in the earthworm metabolism, particularly in the tricarboxylic acid (TCA) and urea cycles. The application of untargeted metabolomics thus provides more information for evaluating the toxic risks of metalaxyl and metalaxyl-M.

Synthesis and Structure Reassignment of Malylglutamate, a Recently Discovered Earthworm Metabolite

Malylglutamate, a newly identified metabolite in earthworms, was synthesized using a traditional peptide coupling approach for assembling the amide from protected malate and glutamate precursors. The proposed structure (1) and a diastereomer were synthesized, but their NMR spectra did not match the natural sample. Further analysis of the natural sample using HMBC spectroscopy suggested an alternative attachment of the malyl moiety, and β-malylglutamate (2) diastereomers were synthesized, L,L-2 and D,D-2. NMR spectra were an excellent match with the natural sample, and chiral-phase chromatography was employed to identify (-)-β-l-malyl-l-glutamate (2) as the isomer native to Eisenia fetida.

Untargeted metabolomics reveals transformation pathways and metabolic response of the earthworm Perionyx excavatus after exposure to triphenyl phosphate

Triphenyl phosphate (TPHP) is one of the most highly utilized organophosphorus flame retardants, and has been frequently detected in various environmental matrices, including soil. So far, limited information is known regarding the potential toxicity of TPHP to the earthworm-soil ecosystem. We investigated the metabolism of TPHP and the perturbation of the endogenous metabolome in the earthworm, Perionyx excavatus, using gas chromatography mass spectrometry (GC-MS) and liquid chromatography quadrupole time-of-flight (LC-QTOF)-based untargeted metabolomics approach after acute exposure to TPHP for one and two days through a filter paper contact test, as well as after chronic exposure for 28 days in a soil microcosm experiment. TPHP showed low bioaccumulation potential in the earthworm-soil ecosystem at concentrations of 10 mg/kg and 50 mg/kg. Identified phase I metabolites include diphenyl phosphate, mono-hydroxylated and di-hydroxylated TPHP. Two groups of phase II metabolites, thiol conjugates (including mercaptolactic acid, cysteine, cysteinylglycine, and mercaptoethanol conjugates) and glucoside conjugates (including glucoside, glucoside-phosphate, and C₁₄H₁₉O₁₀P conjugates), were putatively identified. Only acute TPHP exposure caused significant perturbations of the endogenous metabolome in earthworms, featuring fluctuations in amino acids, glucose, inosine and phospholipids. These results reveal novel phase II metabolism and toxicity of TPHP in P. excavatus.

Metabolic Profiling of Chloroacetanilide Herbicides in Earthworm Coelomic Fluid Using 1H NMR and GC-MS

Earthworms ( Eisenia fetida) are vital members of the soil environment. Because of their sensitivity to many contaminants, monitoring earthworm metabolism may be a useful indicator of environmental stressors. Here, metabolic profiles of exposure to five chloroacetanilide herbicides and one enantiomer (acetochlor, alachlor, butachlor, racemic metolachlor, S-metolachlor, and propachlor) are observed in earthworm coelomic fluid using proton nuclear magnetic resonance spectroscopy (NMR) and gas chromatography-mass spectrometry (GC-MS). Multiblocked-orthogonal partial least-squares-discriminant analysis (MB-OPLS-DA) and univariate analysis were used to identify metabolic perturbations in carnitine biosynthesis, carbohydrate metabolism, lipid metabolism, nitrogen metabolism, and the tricarboxylic acid cycle. Intriguingly, stereospecific metabolic responses were observed between racemic metolachlor and S-metolachlor exposed worms. These findings support the utility of coelomic fluid in monitoring metabolic perturbations induced by chloroacetanilide herbicides in nontarget organisms and reveal specificity in the metabolic impacts of herbicide analogues in earthworms.

Analysis of earthworm sublethal toxic responses to atrazine exposure using 1 H nuclear magnetic resonance (NMR)-based metabolomics

Atrazine toxicity to earthworms is still not fully understood, particularly at sublethal concentrations. Because of the ubiquity of atrazine in the environment, it is imperative to understand the impacts of atrazine presence to soil-dwelling organisms. To examine this in detail, we used ¹ H nuclear magnetic resonance (NMR)-based metabolomics to elucidate earthworm (Eisenia fetida) responses after 48 h of atrazine exposure in contact tests. Earthworms were exposed to 4 sublethal concentrations of 362.4, 181.2, 90.6, and 45.3 ng/cm² , which correspond to 1/8th, 1/16th, 1/32nd, and 1/64th of the median lethal concentration (LC50) values, respectively. After exposure, polar metabolites were isolated from earthworm tissues and analyzed using ¹ H NMR spectroscopy. Sublethal atrazine exposure induced a nonmonotonic response with respect to exposure concentration and caused an overall suppression in earthworm metabolism. Maltose, fumarate, malate, threonine/lactate, adenosine-5'-triphosphate (ATP), betaine, scyllo-inositol, glutamate, arginine, and glutamine were the metabolites identified as most sensitive to atrazine exposure. These observed fluctuations in the metabolic profile suggest that atrazine reduced ATP synthesis and negatively impacted the health of earthworms after acute sublethal exposure. Our study also demonstrates the utility of NMR-based metabolomics for the basic assessment of sublethal toxicity, which can then be used for more targeted approaches with other molecular techniques. Environ Toxicol Chem 2018;37:473-480. © 2017 SETAC.

Antioxidant gene expression and metabolic responses of earthworms (Eisenia fetida) after exposure to various concentrations of hexabromocyclododecane

Hexabromocyclododecane (HBCD), a ubiquitous suspected contaminant, is one of the world's most prominent brominated flame retardants (BFRs). In the present study, earthworms (Eisenia fetida) were exposed to HBCD. The expression of selected antioxidant enzyme genes was measured, and the metabolic responses were assessed using nuclear magnetic resonance (NMR) to identify the molecular mechanism of the antioxidant stress reaction and the metabolic reactions of earthworms to HBCD. A significant up-regulation (p < 0.05) of superoxide dismutase (SOD) gene expression was detected, with the highest gene expression level of SOD appearing at a dose of 400 mg kg^-1 dw (2.06-fold, p < 0.01). However, the glutathione transferase (GST) gene expression levels did not differ significantly (p > 0.05). Principal component analysis (PCA) of the metabolic responses showed that all groups could be clearly differentiated, and the highest concentration dose group was the most distant from the control group. Except for fumarate, the measured metabolites, which included adenosine triphosphate (ATP), valine, lysine, glycine, betaine and lactate, revealed significant (p < 0.05) increases after 14 days of exposure to HBCD. HBCD likely induces high levels of anaerobic respiration, which would result in high levels of ATP and lead to the disintegration of proteins into amino acids, including valine and lysine, to produce energy. The observed changes in osmotic pressure were indicative of damage to the membrane structure. Furthermore, this study showed that NMR-based metabolomics was a more sensitive tool than measuring the gene expression levels for elucidating the mode of toxicity of HBCD in earthworm exposure studies.

1H NMR Metabolic Profiling of Earthworm (Eisenia fetida) Coelomic Fluid, Coelomocytes, and Tissue: Identification of a New Metabolite-Malylglutamate

Earthworm metabolism is recognized as a useful tool for monitoring environmental insults and measuring ecotoxicity, yet extensive earthworm metabolic profiling using ¹H nuclear magnetic resonance (NMR) spectroscopy has been limited in scope. This study aims to expand the embedded metabolic material in earthworm coelomic fluid, coelomocytes, and tissue to aid systems toxicology research. Fifty-nine metabolites within Eisenia fetida were identified, with 47 detected in coelomic fluid, 41 in coelomocytes, and 54 in whole-worm samples and tissue extracts. The newly detected but known metabolites 2-aminobutyrate, nicotinurate, Nδ,Nδ,Nδ-trimethylornithine, and trigonelline are reported along with a novel compound, malylglutamate, elucidated using 2D NMR and high-resolution MS/MS. We postulate that malylglutamate acts as a glutamate/malate store, chelator, and anionic osmolyte and helps to provide electrolyte balance.

Lethal and sub-lethal effects of triclosan toxicity to the earthworm Eisenia fetida assessed through GC-MS metabolomics

Triclosan (TCS) is a ubiquitous contaminant in municipal biosolids, which has also been detected in soils and earthworms sampled from agricultural fields amended with biosolids. The goal of this study was to evaluate the toxicity of TCS to earthworms using a metabolomics-based approach for an improved interpretation of toxicity. Toxicity of TCS was assessed using the OECD Method 207 filter paper contact test measuring the endpoints of weight loss, mortality, and ten metabolites determined by GC-MS. Eight earthworms were exposed as individual replicates to six concentrations of triclosan (0, 0.0001, 0.001, 0.01, 0.1, and 1mg TCS cm^-2) on filter paper, with mortality assessed after 6, 24 and 48h. Mortalities were first observed at 24h, with 100% mortality in the 1 and 0.1mgcm^-2 treatments. Worms at 1mgcm^-2 lost most of their coelomic fluid before they could be sampled. The 48h LC₅₀ for triclosan was estimated to be 0.006 and 0.008mgcm^-2 by a linear and logistic model, respectively. Based on the LC₅₀, triclosan is relatively more toxic to earthworms than a number of other emerging contaminants, but is less toxic than other chlorophenols and many pesticides. Alanine, valine, leucine, serine, phenylalanine, putrescine, spermidine, mannitol, and inositol were significantly different between treatments, although changes were most often associated with mortality rather than triclosan exposure. An increase in putrescine and decrease in amino acids, polyols, and spermidine were associated with mortality, suggesting decomposition had begun. Principal components analysis did not reveal evidence of metabolic impacts at sub-lethal concentrations. However, there were changes in the pattern of correlations between metabolite pairs in surviving worms at both 0.0001 and 0.001mgcm^-2 exposure compared to the control.

Effects of oxidative stress reaction for the Eisenia fetida with exposure in Cd2

Earthworms are widely used in all kinds of pollutants as sensitive bio-indicator organisms because of their immediately oxidative stress response under the stress of heavy metal. However, there are a large number of indexes associated with the oxidative stress response. Finding out the key monitoring indexes in the stress process becomes a practical demand of the pollution monitoring and warning process. We studied two groups, the short-term test and the long-term test. The former one is for 10 days, taking out an earthworm every day. The latter test lasted 30 days, taking out an earthworm every 10 days. The Cd²⁺ concentration was set at 50, 100, 125, 250, and 500 mg kg^-1. Post-clitellum segments of earthworms were chosen to determine superoxide enzyme (SOD), peroxidase (POD), glutathione peroxidase (GSH-Px), glutathione-S transferase (GST), catalase (CAT), vitamin E (VE), malondialdehyde (MDA), and acetylcholinesterase (AChE). The results showed that the main bio-indicators associating with oxidative stress reaction in short-term group were CAT, SOD, and POD. MDA could be used as a bio-indicator in the early and mid-term. VE was only the bio-indicator in the mid-term stress. While with the long-term test, the main bio-indicators associated with oxidative stress reaction were GSH-Px and MDA. The AChE activity was only suitable for oxidative stress response caused by heavy metal stress more than 30 days.

Unexpected effects of sublethal doses of insecticide on the peripheral olfactory response and sexual behavior in a pest insect

Pesticides have long been used as the main solution to limit agricultural pests, but their widespread use resulted in chronic or diffuse environmental pollutions, development of insect resistances, and biodiversity reduction. The effects of low residual doses of these chemical products on organisms that affect both targeted species (crop pests) but also beneficial insects became a major concern, particularly because low doses of pesticides can induce unexpected positive--also called hermetic--effects on insects, leading to surges in pest population growth at greater rate than what would have been observed without pesticide application. The present study aimed to examine the effects of sublethal doses of deltamethrin, one of the most used synthetic pyrethroids, known to present a residual activity and persistence in the environment, on the peripheral olfactory system and sexual behavior of a major pest insect, the cotton leafworm Spodoptera littoralis. We highlighted here a hormetic effect of sublethal dose of deltamethrin on the male responses to sex pheromone, without any modification of their response to host-plant odorants. We also identified several antennal actors potentially involved in this hormetic effect and in the antennal detoxification or antennal stress response of/to deltamethrin exposure.

Development of an NMR microprobe procedure for high-throughput environmental metabolomics of Daphnia magna

Nuclear magnetic resonance (NMR) is the primary platform used in high-throughput environmental metabolomics studies because its non-selectivity is well suited for non-targeted approaches. However, standard NMR probes may limit the use of NMR-based metabolomics for tiny organisms because of the sample volumes required for routine metabolic profiling. Because of this, keystone ecological species, such as the water flea Daphnia magna, are not commonly studied because of the analytical challenges associated with NMR-based approaches. Here, the use of a 1.7-mm NMR microprobe in analyzing tissue extracts from D. magna is tested. Three different extraction procedures (D2O-based buffer, Bligh and Dyer, and acetonitrile : methanol : water) were compared in terms of the yields and breadth of polar metabolites. The D2O buffer extraction yielded the most metabolites and resulted in the best reproducibility. Varying amounts of D. magna dry mass were extracted to optimize metabolite isolation from D. magna tissues. A ratio of 1-1.5-mg dry mass to 40 µl of extraction solvent provided excellent signal-to-noise and spectral resolution using (1)H NMR. The metabolite profile of a single daphnid was also investigated (approximately 0.2 mg). However, the signal-to-noise of the (1)H NMR was considerably lower, and while feasible for select applications would likely not be appropriate for high-throughput NMR-based metabolomics. Two-dimensional NMR experiments on D. magna extracts were also performed using the 1.7-mm NMR probe to confirm (1)H NMR metabolite assignments. This study provides an NMR-based analytical framework for future metabolomics studies that use D. magna in ecological and ecotoxicity studies.

Whole transcriptome analysis using next-generation sequencing of sterile-cultured Eisenia andrei for immune system research

Recently, earthworms have become a useful model for research into the immune system, and it is expected that results obtained using this model will shed light on the sophisticated vertebrate immune system and the evolution of the immune response, and additionally help identify new biomolecules with therapeutic applications. However, for earthworms to be used as a genetic model of the invertebrate immune system, basic molecular and genetic resources, such as an expressed sequence tag (EST) database, must be developed for this organism. Next-generation sequencing technologies have generated EST libraries by RNA-seq in many model species. In this study, we used Illumina RNA-sequence technology to perform a comprehensive transcriptome analysis using an RNA sample pooled from sterile-cultured Eisenia andrei. All clean reads were assembled de novo into 41,423 unigenes using the Trinity program. Using this transcriptome data, we performed BLAST analysis against the GenBank non-redundant (NR) database and obtained a total of 12,285 significant BLAST hits. Furthermore, gene ontology (GO) analysis assigned 78 unigenes to 24 immune class GO terms. In addition, we detected a unigene with high similarity to beta-1,3-glucuronyltransferase 1 (GlcAT-P), which mediates a glucuronyl transfer reaction during the biosynthesis of the carbohydrate epitope HNK-1 (human natural killer-1, also known as CD57), a marker of NK cells. The identified transcripts will be used to facilitate future research into the immune system using E. andrei.

FT-IR spectroscopy as a sentinel technology in earthworm toxicology

FT-IR spectroscopy is a useful tool for determining the biomolecular profile of micro-samples of body fluids such as coelomic fluid of earthworms. The present study focuses on the usefulness of the earthworm (Perionyx sansibaricus) coelomic fluid for observing pathologically induced biochemical changes. Compared to controls, appreciable changes in expression of peaks were observed in worms exposed to seven selected xenobiotics (pesticides, heavy metals, herbicides and detergents). Observation of bands in the region 1600-1690 cm(-1) indicates the presence of amide I band in all the worms. The peak at 2364 cm(-1) present as a weak band on day 7 of treatment, is shifted to 2358/2359 cm(-1) and more pronounced in most of the treated groups on day 14. Presence of band at 1663 cm(-1) in controls is attributed to CO stretching vibration representing the amino acid, glutamic acid. Under toxicological conditions vibration in this region is absent. Presence of the amino acid arginine (1633 cm(-1)) and lysine (1629 cm(-1)) and absence of glutamic acid (1663 cm(-1)) under toxicological stress were characteristic. FT-IR spectra of the coelomic fluid were similar under the sublethal and lethal concentrations of the test chemicals. The potential use of FT-IR spectral information as baseline data for toxicological studies and for monitoring the quality of the environment is recommended.

1-D and 2-D NMR-based metabolomics of earthworms exposed to endosulfan and endosulfan sulfate in soil

One-dimensional (1-D) and two-dimensional (2-D) nuclear magnetic resonance (NMR)-based metabolomics was used to investigate the toxic mode of action (MOA) of endosulfan, an organochlorine pesticide, and its degradation product, endosulfan sulfate, to Eisenia fetida earthworms in soil. Three soil concentrations (0.1, 1.0 and 10.0 mg/kg) were used for both endosulfan and endosulfan sulfate. Both earthworm coelomic fluid (CF) and tissues were extracted and then analyzed using (1)H and (1)H-(13)C NMR techniques. A similar separation trajectory was observed for endosulfan and endosulfan sulfate-exposed earthworms in the mean principal component analysis (PCA) scores plot for both the earthworm CF and tissue extracts. A neurotoxic and apoptotic MOA was postulated for both endosulfan and endosulfan sulfate exposed earthworms as significant fluctuations in glutamine/GABA-glutamate cycle metabolites and spermidine were detected respectively. This study highlights the application of NMR-based metabolomics to understand molecular-level toxicity of persistent organochlorine pesticides and their degradation products directly in soil.