Whole-organism transcriptomic analysis provides mechanistic insight into the acute toxicity of emamectin benzoate in Daphnia magna (original) (raw)
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Aquatic Toxicology, 2012
The potential impact of commercial salmon aquaculture along the coast of British Columbia on the health of non-target marine wildlife is of growing concern. In the current initiative, the biological effects on gene expression within spot prawn (Pandalus platyceros) exposed to the sea lice controlling agent, emamectin benzoate (EB; 0.1-4.8 mg/kg sediment), were investigated. A mean sediment/water partitioning coefficient (K p) was determined to be 21.81 and significant levels of EB were detected in the tail muscle tissue in all exposed animals. Animals selected for the experiment did not have eggs and were of similar weight. Significant mortality was observed within 8 days of EB treatment at concentrations between 0.1 and 0.8 mg/kg and there was no effect of EB on molting. Twelve spot prawn cDNA sequences were isolated from the tail muscle either by directed cloning or subtractive hybridization of control versus EB exposed tissues. Three of the transcripts most affected by EB exposure matched sequences encoding the 60S ribosomal protein L22, spliceosome RNA helicase WM6/UAP56, and the intracellular signal mediator histidine triad nucleotide binding protein 1 suggesting that translation, transcription regulation, and apoptosis pathways were impacted. The mRNA encoding the molting enzyme, -N-acetylglucosaminidase, was not affected by EB treatment. However, the expression of this transcript was extremely variable making it unsuitable for effects assessment. The results suggest that short-term exposure to EB can impact biological processes within this non-target crustacean.
Aquaculture, 2011
Caligus rogercresseyi is a sea louse that affects salmon farming industry throughout the Southern hemisphere. In Chile, oral delivery of emamectin benzoate (EMB) to salmon was the main treatment used; however, C. rogercresseyi became resistant to EMB. The aims of this study were determine the effect of EMB on proteins involved in metabolism and drug resistance in rainbow trout (Oncorhynchus mykiss) and C. rogercresseyi. Since no commercial antibodies are available for these salmon's proteins, the expression of trout cytochrome P450 CYP2K1, CYP2M1, CYP3A and CYP3A27, and the multidrug transporters Pgp and MRP1 were investigated by semi-quantitative duplex RT-PCR. Trout specimens infested with C. rogercresseyi were medicated with EMB by a standard seven-day oral treatment in salmon farms from southern Chile, and collected between 10 and 25 days after the completion of medication. The samples examined were liver, muscle, gill, middle kidney and intestine from control and EMB treated rainbow trout, and C. rogercresseyi's total homogenates. In trout tissues most CYP and MDR gene expressions were up-regulated by EMB treatment, being MRP1 mRNA in all tissues, but particularly in the kidney and intestine, and CYP2M1 mRNA from muscle and gill, the most augmented. CYP3A, CYP3A27, CYP2K1 and Pgp mRNAs were slightly affected in the most tissues analyzed. In C. rogercresseyi minimal up-regulation of the expression for most of mRNA analyzed was observed, except for CYP2M1 mRNA, decreasing its expression by half, and CYP3A27 doubling its expression levels. Nonetheless, CYP3A mRNA expression was not detected in this parasite. These results suggest that treatment with EMB in salmon regulates the transcriptional expression of proteins involved in metabolism, distribution and elimination of endobiotics and xenobiotics, such as hormones and drugs, and even could affect the pharmacokinetics of EMB in the same treatment.► We examined transcriptional effect of emamectin benzoate on rainbow trout and Caligus rogercresseyi. ► Emamectin benzoate is used as antiparasitic against Caligus rogercresseyi. ► Most CYP and MDR genes expression were up-regulated in trout tissues ► MRP1 mRNA was the most augmented. ► In Caligus rogercresseyi minimal up-regulation was observed.
Aquatic Toxicology, 2014
This study describes the function of transcripts with altered abundance in the epibenthic amphipod, Melita plumulosa, following whole-sediment exposure to a series of common environmental contaminants. M. plumulosa were exposed for 48 h to sediments spiked and equilibrated with the following contaminants at concentrations predicted to cause sublethal effects to reproduction: porewater ammonia 30 mg L −1 ; bifenthrin at 100 g kg −1 ; fipronil at 50 g kg −1 ; 0.6% diesel; 0.3% crude oil; 250 mg Cu kg −1 ; 400 mg Ni kg −1 ; and 400 mg Zn kg −1 . RNA was extracted and hybridized against a custom Agilent microarray developed for this species. Although the microarray represented a partial transcriptome and not all features on the array could be annotated, unique transcriptomic profiles were generated for each of the contaminant exposures. Hierarchical clustering grouped the expression profiles together by contaminant class, with copper and zinc, the petroleum products and nickel, and the pesticides each forming a distinct cluster. Many of the transcriptional changes observed were consistent with patterns previously described in other crustaceans. The changes in the transcriptome demonstrated that contaminant exposure caused changes in digestive function, growth and moulting, and the cytoskeleton following metal exposure, whereas exposure to petroleum products caused changes in carbohydrate metabolism, xenobiotic metabolism and hormone cycling. Functional analysis of these gene expression profiles can provide a better understanding of modes of toxic action and permits the prediction of mixture effects within contaminated ecosystems.
Ecotoxicology and Environmental Safety, 2012
The marine copepod, Amphiascus tenuiremis (A. tenuiremis), is a well characterized invertebrate model for the screening and evaluation of endocrine and reproductive toxins using life-cycle assays. These tests evaluate phenotypic endpoints related to development and reproduction, which are utilized to predict population outcomes. Some of these endpoints in arthropods, including sexual maturation and molting, are controlled by the hormone ecdysone which acts through its cognate receptor, the ecdysone receptor. The purpose of this research was to obtain and characterize sequence information for the A. tenuiremis ecdysone receptor and investigate modulation of expression levels by fipronil, an insecticide that causes infertility in males and reduced egg extrusion in female copepods, and ponasterone, a natural ecdysone receptor agonist. Results show successful cloning and phylogenetic analysis of the ecdysone receptor for A. tenuiremis, providing the first genetic information for a hormone receptor in this species. Exposure of copepodites to fipronil for 1, 2, 4, 18 and 30 h caused a significant increase in ecdysone receptor transcriptional expression at 30 h compared to control unexposed animals. This work illustrates a potential mechanism whereby exposure to fipronil, and potentially other endocrine disrupting compounds, results in impacted reproduction. Furthermore, this exemplifies the potential utility of ecdysone receptor transcriptional measurement as a sensitive and rapid biomarker of ecological relevance when linked to traditional A. tenuiremis bioassays.
Aquatic Toxicology, 2009
Transcriptome profiling in crustaceans as a tool for ecotoxicogenomics
Cell Biology and Toxicology, 2008
Chemicals released into the environment have the potential to affect various species and it is important to evaluate such chemical effect on ecosystems, including aquatic organisms. Among aquatic organisms, Daphnia magna has been used extensively for acute toxicity or reproductive toxicity tests. Although these types of tests can provide information on hazardous concentrations of chemicals, they provide no information on their mode of action. Recent advances in toxicogenomics, the integration of genomics with toxicology, have the potential to afford a better understanding of the responses of aquatic organisms to pollutants. In a previous study, we developed an oligonucleotide-based DNA microarray with high reproducibility using a Daphnia expressed sequence tag (EST) database. In this study, we increased the number of genes on the array and used it for a careful ecotoxicogenomic assessment of Daphnia magna. The DNA microarray was used to evaluate gene expression profiles of neonate daphnids exposed to beta-naphthoflavone (bNF). Exposure to this chemical resulted in a characteristic gene expression pattern. As the number of the genes on an array was increased, the number of genes that were found to respond to the chemicals was also increased, which made the classification of the toxic chemicals easier and more accurate. This newly developed DNA microarray can be useful for a obtaining a better mechanistic understanding of chemical toxicity effects on a common freshwater organism.
International Journal of Molecular Sciences, 2016
Scientific efforts to elucidate the mechanisms of chemical communication between organisms in marine environments are increasing. This study applied novel molecular technology to outline the effects of two xenobiotic drugs, deltamethrin (DM) and azamethiphos (AZA), on the neurotransmission system of the copepod ectoparasite Caligus rogercresseyi. Transcriptome sequencing and bioinformatics analyses were conducted to evaluate treatment effects on the glutamatergic synaptic pathway of the parasite, which is closely related to chemoreception and neurotransmission. After drug treatment with DM or AZA, stochastic mRNA expression patterns of glutamatergic synapse pathway components were observed. Both DM and AZA promoted a down-regulation of the glutamate-ammonia ligase, and DM activated a metabotropic glutamate receptor that is a suggested inhibitor of neurotransmission. Furthermore, the delousing drugs drove complex rearrangements in the distribution of mapped reads for specific metabotropic glutamate receptor domains. This study introduces a novel methodological approach that produces high-quality results from transcriptomic data. Using this approach, DM and AZA were found to alter the expression of numerous mRNAs tightly linked to the glutamatergic signaling pathway. These data suggest possible new targets for xenobiotic drugs that play key roles in the delousing effects of antiparasitics in sea lice.
The toxicity of emamectin benzoate, an aquaculture pesticide, to planktonic marine copepods
Aquaculture, 2003
The acute and sublethal toxicity of emamectin benzoate to non-target planktonic marine copepods was determined. Emamectin benzoate is the active ingredient in SliceR, an in-feed pesticide formulation used to control parasitic sea lice in salmon aquaculture. The comparative sensitivity of three life stages (nauplii, copepodites, adults) of four common marine copepods (Acartia clausi, Pseudocalanus elongatus, Temora longicornis and Oithona similis) was assessed in 48-h exposures followed by a recovery period in toxicant-free sea water. The calanoid copepods responded similarly to emamectin benzoate and EC50 values were significantly lower than those for the cyclopoid O. similis. Nauplii and copepodite 48-h EC50 values were generally lower than those for the adults. EC50 values ranged from 0.12 Ag/l (P. elongatus nauplii) to 232 Ag/l (O. similis adults). The primary toxic effect, immobilisation, was generally irreversible. A 7-day sublethal test with adult A. clausi females measured a significant reduction in egg production at higher concentrations. The noobserved-effect-concentration (NOEC) and lowest-observed-effect-concentration (LOEC) values were 0.05 and 0.158 Ag/l, respectively. Concentrations causing toxicity to planktonic copepods were considerably higher than Predicted Environmental Concentrations (PEC) in the vicinity of treated salmon farms and suggest that the use of emamectin benzoate for lice control is unlikely to adversely affect planktonic copepods. D
The chronic toxicity of emamectin benzoate to three marine benthic species using microcosms
Ecotoxicology and Environmental Safety
The commercial farming of Atlantic salmon, Salmo salar, may require the periodic application of emamectin benzoate (EB) treatments to reduce the effects of biological pests, such as sea lice. As a result, EB is detected in sediments beneath these fish farms at considerable levels. Literature sediment toxicity data for EB for marine benthic species is only available for 10-day sediment toxicity tests, which might be too short to assess field effects. Here, we present a sediment toxicity test to determine 28-day mortality and growth effect concentrations for the non-target polychaete worm Arenicola marina, the crustacean Corophium volutator and the mollusk Cerastoderma edule using a marine microcosm setup. Results indicate that no concentration-dependent increase of mortality and growth rate was apparent to A. marina and C. edule. But for C. volutator, a concentrationdependent increase in mortality was observed, resulting in a calculated 28-d LC50 of 316 μg/kg dry sediment (95% confidence interval: 267-373 μg/kg dry sediment). There were significant effects on C. volutator growth rate at concentrations of 100 μg/kg dry sediment and above (NOEC = 30 μg/kg dry sediment). These observations show that C. volutator is more sensitive to EB than A. marina, which differs from results reported in previous studies. Comparison to the most sensitive NOEC (30 μg/kg dry sediment) found for C. volutator (organisms of 8-11 mm length), shows that the Environmental Quality Standard, derived by the Scottish Environment Protection Agency in 2017 which based on freshwater species data (NOEC = 1.175 μg/kg dry sediment), are relatively strict and is sufficiently protective for the marine species tested in this paper.