Transcriptome information of the Arctic green sea urchin and its use in environmental monitoring

Abstract

The Arctic sea urchin Strongylocentrotus droebachiensis is considered to be a potential indicator species for assessing aquatic environmental conditions in the polar region. To develop a gene resource for the Arctic sea urchin, we sequenced S. droebachiensis cDNAs using a GS-20 sequencer and obtained expressed sequence tags information. In the assembly stage, 31,526 transcripts were obtained and showed a 32 % hit rate in the GenBank nonredundant database with 9,995 unigenes. Of the transcripts obtained in this species, we found several stress- and cellular defense-related genes (antioxidant-related genes and genes from the heat shock protein family) that are useful for the monitoring of pollutant-triggered stress responses at the molecular level. To validate the usefulness of these potential biomarker genes, we analyzed the transcript profiles of selected genes in response to polychlorinated biphenyls (PCB) mixtures (Aroclor 1254) for 48 h. PCB contamination is a present-day threat to the health of individual organisms and ecosystems in the polar region. We showed that 11 of 14 genes responded to PCB treatment at transcriptional levels, with the most dramatic upregulation observed in the hsp70.5 gene. In this paper, we summarize the expressed cDNA information and discuss its potential use in ecotoxicological genomic studies on PCB exposure.