Biomarker Discovery and Transcriptomic Responses in Daphnia magna exposed to Munitions Constituents

Abstract

Ecotoxicogenomic approaches are emerging as alternative methods in environmental monitoring because they allow insight into pollutant modes of action and help assess the causal agents and potential toxicity beyond the traditional end points of death, growth, and reproduction. Gene expression analysis has shown particular promise for identifying gene expression biomarkers of chemical exposure that can be further used to monitor specific chemical exposures in the environment. We focused on the development of gene expression markers to detect and discriminate between chemical exposures. Using a custom cDNA microarray for Daphnia magna, we identified distinct expression fingerprints in response to exposure at sublethal concentrations of Cu, Zn, Pb, and munitions constituents. Using the results obtained from microarray analysis, we chose a suite of potential biomarkers for each of the specific exposures. The selected potential biomarkers were tested in independent chemical exposures for specificity using quantitative reverse transcription polymerase chain reaction. Six genes were confirmed as differentially regulated bythe selected chemical exposures. Furthermore, each exposure was identified by response of a unique combination (suite) of individual gene expression biomarkers. These results demonstrate the potential for discovery and validation of novel biomarkers of chemical exposures using gene expression analysis, which could have broad applicability in environmental monitoring.

Review and synthesis of evidence regarding environmental risks posed by munitions constituents (MC) in aquatic systems

“…Advances in molecular biology are extending the use of biomarkers to the level of the genes, which, when coupled with bioinformatics, are progressing toward the development of screening tools for ecotoxicologists. Environmental genomics (using gene expression profiles after exposure to toxicants, also called toxicogenomics) allow insight into modes of action that may be used to assess causal agents and potential toxicity (Garcia-Reyero et al 2009). Recent research goals include development of robust methods for using gene expression analysis when identifying gene expression biomarkers of chemical exposure that can be further used to monitor specific chemical exposures in the environment (Garcia-Reyero et al 2009, 2012.…”

“…Environmental genomics (using gene expression profiles after exposure to toxicants, also called toxicogenomics) allow insight into modes of action that may be used to assess causal agents and potential toxicity (Garcia-Reyero et al 2009). Recent research goals include development of robust methods for using gene expression analysis when identifying gene expression biomarkers of chemical exposure that can be further used to monitor specific chemical exposures in the environment (Garcia-Reyero et al 2009, 2012. Gust et al (2011a) conducted a comprehensive investigation of the effects RDX exposure elicited on transcript expression in fathead minnow brain tissue.…”

Gene transcription profiles, global DNA methylation and potential transgenerational epigenetic effects related to Zn exposure history in Daphnia magna

“…In the past few years, microarrays have been developed for Daphnia magna, a key species in aquatic toxicology and ecology. These tools have subsequently been used to evaluate the effects of exposure to different types of chemicals on gene transcription in D. magna (Soetaert et al, 2007;Garcia-Reyero et al, 2009;Vandenbrouck et al, 2009).…”

Endocrinology: Advances through omics and related technologies

“…While Daphnia has long been used in biomedical research to study cellular immunity, phenotypic plasticity, or genetic heritability among others (Ebert, 2011;Kocabas et al, 2006), the recent advance on genetic tools coupled with the release of the Daphnia pulex genome (Colbourne et al, 2011), the first crustacean genome ever sequenced, rapidly promoted the use of Daphnia as a model species. Transcriptomic profiling of Daphnia magna was rapidly embraced as a tool for ecotoxicogenomics research (Garcia-Reyero et al, 2012, 2009bWatanabe et al, 2008Watanabe et al, , 2007. Ceriodaphnia dubia has been proposed as a cost-effective alternative to Daphnia due to their shorter life cycle, while providing similar outcomes in toxicological studies (Constantine and Huggett, 2010).…”