Gene expression profiling of copper-induced responses in the intertidal copepod Tigriopus japonicus using 6K oligochip microarray

Department of Chemistry, College of Natural Sciences, Hanyang University, Seoul 133-791, South Korea.
Aquatic toxicology (Amsterdam, Netherlands) (Impact Factor: 3.45). 05/2009; 93(4):177-87. DOI: 10.1016/j.aquatox.2009.04.004
Source: PubMed


The intertidal copepod Tigriopus japonicus has shown promising results in classical acute and chronic toxicity studies. Recently, a large number of genes have been identified from this species and their mRNA expression has been studied independently against exposure to marine environmental pollutants. T. japonicus is a promising organism for the study of mechanistic aspects of marine environmental pollutants using genomics. In this study, a 6K oligochip for T. japonicus that included mostly unique sets of genes from approximately 26K ESTs, was developed. A total of 5463 spots (2313 mRNAs upregulated and 3150 downregulated) were identified to be significantly expressed on microarray by hierarchical clustering of genes after exposure to copper for different time durations (10 microg/L for 6, 12 and 24h). However, mRNAs of only 138 and 375 genes were observed to be consistently upregulated and downregulated, respectively, at all time points. Most of the changes of mRNA expression were observed at the short exposure of 6h. It was observed that mRNA expression of several genes involved in growth, metabolism, reproduction and hormonal regulation was modulated in Cu-exposed T. japonicus. mRNA expression of genes involved in detoxification and antioxidant functions was also modulated. This indicates that Cu-induced gene transcription is complicated in T. japonicus similar to other crustaceans. Cu specifically upregulated mRNAs of genes of some isoforms of cytochrome P450 (CYP). On the other hand, a majority of downregulated mRNAs were of genes encoding for proteins important for growth and development. The expression profile of mRNAs of selected genes was verified by the quantitative real time RT-PCR. The mRNA expression profiles provide insight into the mechanism of action of copper in T. japonicus. These results demonstrate the suitability of a T. japonicus oligochip microarray for risk assessment of trace metals in the marine environment. As yet, major breakthroughs in invertebrate toxicogenomics have mainly been in Daphnia and Drosophila. Daphnia's use is limited to freshwater ecotoxicogenomics. Here we propose an oligochip microarray-based approach for risk assessment of trace metals in a potential model marine test species.

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Available from: Jae-Sung Rhee
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    • "These characteristics make it a potential sentinel species for aquatic ecotoxicological studies (Raisuddin et al., 2007). The use of T. japonicus in acute ecotoxicity studies, transgenerational toxicity, and gene expression studies have demonstrated its potentials as a model organism (Lee et al., 2008; Ki et al., 2009; Rhee et al., 2009; Guo et al., 2012; Kim et al., 2013). However, there is a paucity of information regarding the toxic effect of b-NF in T. japonicus and other copepods with reference to oxidative stress, although extensive ecotoxicological studies using T. japonicus have been performed with several environmental pollutants (Marcial et al., 2003; Kwok and Leung, 2005; Lee et al., 2007; Raisuddin et al., 2007). "
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    ABSTRACT: β-Naphtoflavone (β-NF) is a flavonoid and enhances oxidative stress in vertebrates with little information from aquatic invertebrates as yet. In this study, we investigated the effects of β-NF on the antioxidant defense systems of the intertidal copepod Tigriopus japonicus. To measure the β-NF-triggered changes in oxidative stress markers, such as intracellular reactive oxygen species (ROS), glutathione (GSH) concentration, residual glutathione S-transferase (GST), glutathione peroxidase (GPx), glutathione reductase (GR), and superoxide dismutase (SOD) activity, T. japonicus were exposed to β-NF (0.5 and 1 mg/L) for 72 h. Significant (P < 0.05) induction of the intracellular ROS content (%) was observed in 1 mg/L of β-NF exposed T. japonicus, compared to the negative control and H2 O2 -exposed group. The GSH levels were significantly increased in the 0.5 mg/L of β-NF-exposed group for 12 h and 1 mg/L of β-NF-exposed groups for 12-24 h. GPx, GST, and GR activities showed a significant increase in the 1 mg/L β-NF-exposed group, indicating that β-NF induces oxidative stress in T. japonicus. To understand the effects of β-NF at the level of transcript expression, a 6K microarray analysis was employed. Transcript profiles of selected antioxidant-related genes were modulated after 72 h exposure to 1 mg/L of β-NF. From microarray data, 10 GST isoforms, GR, GPx, PH-GPx, and Se-GPx were chosen for a time-course test by real-time RT-PCR. T. japonicus GST-S, GST-O, GST-M, and GST-D1 were significantly increased in a 1 mg/L β-NF-exposed group. T. japonicus GPx, GR, and Se-GPx mRNA levels were also significantly increased at both concentrations. Our results revealed that oxidative stress was induced by β-NF exposure in T. japonicus. © 2013 Wiley Periodicals, Inc. Environ Toxicol, 2013.
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    • "Tigriopus spp. respond to a variety of relevant environmental toxicants through standard toxicity end points such as LC 50 (Lee et al., 2007) life-history traits (Kwok et al., 2008; Lee et al., 2008; Kwok et al., 2009), and through gene expression (Seo et al., 2006; Ki et al., 2009). These characteristics make Tigriopus a tractable marine model for ecotoxicological studies (Raisuddin et al., 2007). "
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    • "Based on the chronic toxicity results, three TPTCl concentrations were selected as the three treatment groups (i.e., 0.1, 0.5 and 1 lg/L) plus a seawater control; there were three replicates for each treatment or the control. For each replicate, around 200 copepods were added to a test tube with 50 mL of the corresponding test solution and collected after 24 h exposure (Ki et al. 2009; Kim et al. 2013). Test conditions were identical to those applied in the acute toxicity test. "
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