Seonock Woo 1 , Seungshic Yum 1 , Hong-Seog Park 2 , Jee Hyun Jung 1 , Sukchan Lee 3 , So Jung Kim 4 & Taek Kyun Lee 1 1 Southern Coastal Environment Research Division, Korea Ocean Research and Development Institute, Geoje 656-830, Korea 2 Genome Research Center, Korea Research Institute of Bioscience and Technology, Daejeon 305-333, Korea 3 Department of Genetic Engineering, Sungkyunkwan University, Suwon 440-746, Korea 4 Gyeongbuk Institute for Marine Bioindustry, Uljin 767-813, Korea Correspondence and requests for materials should be addressed to T. K. Lee (tklee@kordi.re.kr) Accepted 16 October 2007 Abstract Environmental and anthropogenic changes affect the health and stability of marine ecosystem. In this study we aimed to identify molecular biomarkers for ecotoxicological pollutants risk assessment in the rockfish (Sebastes schlegeli ). We designed primers based on conserved sequences by multiple align- ments of target genes from related species, and clon- ed the partial cDNAs of cytochrome P450 (CYP1A1), glutathione S-transferase (GST), metallothionein (MT), superoxide dismutase (SOD), ubiquitin (UB), vitellogenin (VTG) and β-actin by reverse transcrip- tion polymerase chain reaction (RT-PCR) from S. schlegeli. Northern blot results indicated that these six genes expressions were significantly induced by benzo[a]pyrene (BaP, 1 µM) and that the level of each of their transcripts increased in BaP-exposed rock- fish in a time-dependent manner. This study sug- gests that transcriptional changes in these six genes may be used for monitoring environmental exposure to polycyclic aromatic hydrocarbons (PAHs). Keywords: Sebastes schlegeli , Environmental stress, Benzo[a]pyrene, Biomarkers, Gene expression The marine environment is continuously being af- fected by a large number anthropogenic contaminants and stressors that threaten its stability. This is particu- larly true in densely populated and massively develop- ed coastal areas such as the areas involved in ship- building or marine engineering, and the areas conta- minated by various types of land runoffs or sewage. Currently, various methods of biotoxicity assessment have been developed, for example, the analyses of specific enzyme activity variations involved in cellu- lar defense 1 , the use of protein chip technology to fol- low proteomic profiles changes in organisms exposed to environmental toxicants 2 , and the direct determi- nation of DNA strand breaks or levels of PAH meta- bolites in the polluted marine organisms 3 . However, investigations on transcriptional changes in represen- tative genes, which are known to respond to abiotic stressors, are rare in marine organisms. In this study we aimed to develop the integrated biomarkers throu- gh the analyses of transcriptional changes induced by ecotoxicant and as a first step for this approach, we isolated six genes which are known to be related with oxidative stress, heavy metal toxicity, reproductive toxicity, and genotoxicity from rockfish, Sebastes schlegeli. Rockfish, S. schlegeli, distribute in coastal area of Korea and Japan and we choose the rockfish as an experimental animal because of its importance as food resource and considerable easiness on han- dling and obtainment (Figure 1). The integrated use of biomarkers of exposure and knowledge of the effects of oxidative stress, heavy metal toxicity, reproductive toxicity, and genotoxicity in living marine organisms may help us to better inter- pret the impact of pollutants on the marine coastal environment. The molecular tools introduced in this study can provide information on the health of spe- cies and thus contribute to our knowledge of marine ecosystem and provide information on the pollution status of coastal regions. Cloning of CYP1A1, GST, MT, SOD, UB and VTG To clone the target genes, nucleotide sequences were selected in conserved regions as primers after performing multiple alignments of each gene from the known sequences of related species [Dicentrar- chus labrax (CYP1A1), Pleuronectes platessa (GST), Sparus aurata (MT), Acanthopagrus schlegelii (SOD), Pagrus major (UB), Sillago japonica (VTG)]. The primers used to amplify the targeted genes are listed MOLECULAR & CELLULAR TOXICOLOGY, Vol. 3, No. 4, 267-272, December 2007 Molecular Parameters for Assessing Marine Biotoxicity: Gene Expressions of Rockfish (Sebastes schlegeli ) Exposed to Polycyclic Aromatic Hydrocarbons