Uptake of hexanitrohexaazaisowurtzitane (CL-20) by the earthworm Eisenia fetida through dermal contact

Gong, Ping; Escalon, B. Lynn; Hayes, Charolett A.; Perkins, Edward J.

doi:10.1016/j.scitotenv.2007.10.001

Cited by 5 publications

(6 citation statements)

References 11 publications

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“…One milliliter of CL-20 solution in methanol was spread on the filter paper (115 cm 2 ) and methanol was allowed to evaporate before moistening the filter paper with 2 ml of de-ionized water. The concentration of CL-20 in stock solutions (µg CL-20/ml of methanol) was confirmed by HPLC analysis (Gong et al 2008) and was converted into µg/cm 2 to express concentration of exposure. The ε-CL-20 (99.3%) was synthesized by ATK Thiokol Propulsion (China Lake, UT, USA).…”

Section: Methodsmentioning

confidence: 99%

Neurochemical and electrophysiological diagnosis of reversible neurotoxicity in earthworms exposed to sublethal concentrations of CL-20

Gong¹,

Basu

Scheuhammer

et al. 2009

Environ Sci Pollut Res

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Background, aim, and scopeHexanitrohexaazaisowurtzitane (CL-20) is a relatively new energetic compound sharing some degree of structural similarity with hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), a known neurotoxic compound. Previously, we demonstrated using a noninvasive electrophysiological technique that CL-20 was a more potent neurotoxicant than RDX to the earthworm Eisenia fetida. In the present study, we investigated the effect of CL-20 exposure and subsequent recovery on muscarinic acetylcholine receptors (mAChRs) to further define the mechanism of reversible neurotoxicity of CL-20 in E. fetida.Materials and methodsWe used a noninvasive electrophysiological technique to evaluate neurotoxicity in CL-20-treated worms, and then measured how such exposures altered levels of whole-body mAChR in the same animals.Results and discussionA good correlation exists between these two types of endpoints. Effect on mAChR levels was most prominent at day 6 of exposure. After 7 days of recovery, both conduction velocity and mAChR were significantly restored. Our results show that sublethal concentrations of CL-20 significantly reduced mAChR levels in a concentration- and duration-dependent manner, which was accompanied with significant decreases in the conduction velocity of the medial and lateral giant nerve fibers. After 7-day post exposure recovery, worms restored both neurochemical (mAChR) and neurophysiological (conduction velocity) endpoints that were reduced during 6-day exposures to CL-20 concentrations from 0.02 to 0.22 µg/cm2.Conclusions and perspectivesOur findings support the idea that CL-20 induced neurotoxic effects are reversible, and suggest that CL-20 neurotoxicity may be mediated through the cholinergic system. Future studies will investigate other neurotransmission systems such as GABA, glutamate, and monoamine. Ion channels in the nerve membrane should be examined to further define the precise mechanisms underlying CL-20 neurotoxicity.

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Section: Methodsmentioning

confidence: 99%

Neurochemical and electrophysiological diagnosis of reversible neurotoxicity in earthworms exposed to sublethal concentrations of CL-20

Gong¹,

Basu

Scheuhammer

et al. 2009

Environ Sci Pollut Res

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“…A 4-day preliminary exposure experiment to identify appropriate chemical concentrations and the most sensitive analytical method revealed that nominal soil amendment concentrations of 0–96 mg [U– 14 C] TNT/kg or 0–128 mg [U– 14 C] RDX/kg caused no mortality, and that the Combustion–Scintillation Counting (CSC) method (see Section 2.2 for details) had a consistently higher recovery rate of amended chemicals in both soil and earthworm tissues than the SE-HPLC-ECD (Solvent Extraction followed by High Performance Liquid Chromatography coupled with Electrochemical Detector) method and the SE-HPLC-RFD (Solvent Extraction followed by HPLC equipped with Radioactivity Flow Detector) method (see Supporting Information and ref ). In good agreement with previous reports, , our preliminary results also showed that TNT quickly broke down after being amended in soil and little parent compound was recovered in earthworm tissue samples.…”

Section: Methodsmentioning

confidence: 99%

Building Quantitative Prediction Models for Tissue Residue of Two Explosives Compounds in Earthworms from Microarray Gene Expression Data

Gong

Loh

Barker

et al. 2011

Environ. Sci. Technol.

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Soil contamination near munitions plants and testing grounds is a serious environmental concern that can result in the formation of tissue chemical residue in exposed animals. Quantitative prediction of tissue residue still represents a challenging task despite long-term interest and pursuit, as tissue residue formation is the result of many dynamic processes including uptake, transformation, and assimilation. The availability of high-dimensional microarray gene expression data presents a new opportunity for computational predictive modeling of tissue residue from changes in expression profile. Here we analyzed a 240-sample data set with measurements of transcriptomic-wide gene expression and tissue residue of two chemicals, 2,4,6-trinitrotoluene (TNT) and 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), in the earthworm Eisenia fetida. We applied two different computational approaches, LASSO (Least Absolute Shrinkage and Selection Operator) and RF (Random Forest), to identify predictor genes and built predictive models. Each approach was tested alone and in combination with a prior variable selection procedure that involved the Wilcoxon rank-sum test and HOPACH (Hierarchical Ordered Partitioning And Collapsing Hybrid). Model evaluation results suggest that LASSO was the best performer of minimum complexity on the TNT data set, whereas the combined Wilcoxon-HOPACH-RF approach achieved the highest prediction accuracy on the RDX data set. Our models separately identified two small sets of ca. 30 predictor genes for RDX and TNT. We have demonstrated that both LASSO and RF are powerful tools for quantitative prediction of tissue residue. They also leave more unknown than explained, however, allowing room for improvement with other computational methods and extension to mixture contamination scenarios.

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“…The motivation of the present study stems from our previous observations that CL-20, taken up through dermal contact (20), induces neurotoxicity in E. fetida (13), as reflected in reduced whole body muscarinic acetylcholine receptor (mAChR) levels and giant nerve fiber conduction velocity (14). Interestingly, earthworms are capable of recovering rapidly from the neurotoxicity once removed from the stressor CL-20 (13;14).…”

Section: Introductionmentioning

confidence: 99%

“…Although CL-20 does not affect the growth of higher plants such as alfalfa (Medicago sativa) and perennial ryegrass (Lolium perenne), it can accumulate in plants and may pose a potential risk of biomagnification across the food chain. 18,19 The motivation of the present study stems from our previous observations that CL-20, taken up through dermal contact, 20 induces neurotoxicity in E. fetida, 13 as reflected in reduced whole body muscarinic acetylcholine receptor (mAChR) levels and giant nerve fiber conduction velocity. 14 Interestingly, earthworms are capable of recovering rapidly from the neurotoxicity once removed from the stressor CL-20.…”

Section: ■ Introductionmentioning

confidence: 99%

“…The motivation of the present study stems from our previous observations that CL-20, taken up through dermal contact, induces neurotoxicity in E. fetida , as reflected in reduced whole body muscarinic acetylcholine receptor (mAChR) levels and giant nerve fiber conduction velocity . Interestingly, earthworms are capable of recovering rapidly from the neurotoxicity once removed from the stressor CL-20. , To further explore molecular mechanisms underlying the reversible neurotoxicity, we employed a toxicogenomics approach to interrogating transcriptional response to CL-20 exposure and recovery.…”

Section: Introductionmentioning

confidence: 99%

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Gene Expression Analysis of CL-20-Induced Reversible Neurotoxicity Reveals GABA_AReceptors as Potential Targets in the EarthwormEisenia fetida

Gong

Guan

Pirooznia

et al. 2012

Environ. Sci. Technol.

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The earthworm Eisenia fetida is one of the most used species in standardized soil ecotoxicity tests. Endpoints such as survival, growth and reproduction are eco-toxicologically relevant but provide little mechanistic insight into toxicity pathways, especially at the molecular level. Here we applied a toxicogenomic approach to investigate the mode of action underlying the reversible neurotoxicity of hexanitrohexaazaisowurtzitane (CL-20), a cyclic nitroamine explosives compound. We developed an E. fetida-specific shotgun microarray targeting 15119 unique E. fetida transcripts. Using this array we profiled gene expression in E. fetida in response to exposure to CL-20. Eighteen earthworms were exposed for 6 days to 0.2 μg/cm2 of CL-20 on filter paper, half of which were allowed to recover in a clean environment for 7 days. Nine vehicle control earthworms were sacrificed at day 6 and 13, separately. Electrophysiological measurements indicated that the conduction velocity of earthworm medial giant nerve fiber decreased significantly after 6-day exposure to CL-20, but was restored after 7 days of recovery. Total RNA was isolated from the four treatment groups including 6-day control, 6-day exposed, 13-day control and 13-day exposed (i.e. 6-day exposure followed by 7-day recovery), and was hybridized to the 15K shot-gun oligo array. Statistical and bioinformatic analyses suggest that CL-20 initiated neurotoxicity by non-competitively blocking the ligand-gated GABAA receptor ion channel, leading to altered expression of genes involved in GABAergic, cholinergic, and Agrin-MuSK pathways. In the recovery phase, expression of affected genes returned to normality, possibly as a result of autophagy and CL-20 dissociation/metabolism. This study provides significant insights into potential mechanisms of CL-20-induced neurotoxicity and the recovery of earthworms from transient neurotoxicity stress.

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Uptake of hexanitrohexaazaisowurtzitane (CL-20) by the earthworm Eisenia fetida through dermal contact

Cited by 5 publications

References 11 publications

Neurochemical and electrophysiological diagnosis of reversible neurotoxicity in earthworms exposed to sublethal concentrations of CL-20

Neurochemical and electrophysiological diagnosis of reversible neurotoxicity in earthworms exposed to sublethal concentrations of CL-20

Building Quantitative Prediction Models for Tissue Residue of Two Explosives Compounds in Earthworms from Microarray Gene Expression Data

Gene Expression Analysis of CL-20-Induced Reversible Neurotoxicity Reveals GABA_AReceptors as Potential Targets in the EarthwormEisenia fetida

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Uptake of hexanitrohexaazaisowurtzitane (CL-20) by the earthworm Eisenia fetida through dermal contact

Cited by 5 publications

References 11 publications

Neurochemical and electrophysiological diagnosis of reversible neurotoxicity in earthworms exposed to sublethal concentrations of CL-20

Neurochemical and electrophysiological diagnosis of reversible neurotoxicity in earthworms exposed to sublethal concentrations of CL-20

Building Quantitative Prediction Models for Tissue Residue of Two Explosives Compounds in Earthworms from Microarray Gene Expression Data

Gene Expression Analysis of CL-20-Induced Reversible Neurotoxicity Reveals GABAAReceptors as Potential Targets in the EarthwormEisenia fetida

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Gene Expression Analysis of CL-20-Induced Reversible Neurotoxicity Reveals GABA_AReceptors as Potential Targets in the EarthwormEisenia fetida