Identification and characterization of expressed sequence tags from the liver of rare minnow (Gobiocypris rarus) Yanhong Wei a,c , Jianshe Wang a , Xiaowei Zhang b , Muqi Xu a , Jiayin Dai a, ⁎ a Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, PR China b Beijing Genomics Institute, Chinese Academy of Sciences, Beijing, 101300, PR China c Graduate School of the Chinese Academy of Sciences, Beijing, 100080, PR China Received 5 July 2007; received in revised form 10 September 2007; accepted 10 September 2007 Available online 16 September 2007 Abstract Rare minnow (Gobiocypris rarus) is a newly developed aquatic test organism that has been widely used in a range of studies of toxicological risk assessment by virtue of its higher sensitivity to xenobiotics. To describe extensively the transcripts expressed in the livers of adult rare minnow, we generated 6919 high-quality expressed sequence tags (ESTs) from a non-normalized cDNA library. After processing, a total of 1773 unigenes (unique genes) comprising 771 contigs (consensus sequences) and 1002 singlets were acquired. Based on the analysis by BLAST, 1512 unigenes (85%) had been identified and annotated. The result of functional classification reveals that the genes involved in the processes of general metabolism prevail in liver expressed genes. In addition, we compiled a potentially toxicology-related catalog comprising 262 unigenes that associated with metabolism of xenobiotics and adaptive responses. There are eleven groups referring to diverse functions in the catalog. This report provides the first set of genetic data for rare minnow which is of great value for further exploitation of this species in functional genomics and toxicogenomics, and sets a basis for the discovery of new molecular markers of exposure and for the production of the function-focused microarray. © 2007 Elsevier Inc. All rights reserved. Keywords: cDNA library; Transcriptomics; Teleosts; Toxicogenomics 1. Introduction Rare minnow (Gobiocypris rarus), a newly developed aquatic test organism, has been reported to be an ideal fish for toxicological risk assessment of a wide range of chemicals (Zhou et al., 2002). Compared with fathead minnow (Pimephales promelas), rainbow trout (Oncorhynchus mykiss), zebrafish (Danio rerio), medaka (Oryzias latipes) and some other aquatic test teleosts recommended by the International Organization for Standardization (ISO), rare minnow has many attractive char- acteristics that make it suitable for aquatic toxicity tests. The characteristics include sensitivity to chemicals, small size, wide temperature range, ease of laboratory culture, and short em- bryonic development period (Zhou et al., 1995; Lu and Shen, 2002). To date, a variety of studies have been conducted utilizing rare minnow to evaluate the impact of many chemicals (Yang and Feng, 2003; Ma et al., 2004; Zhong et al., 2004, 2005; Zha et al., 2007). Although it has been widely recognized and utilized in broader fields of research, there are few genetic resources or any transcriptional data about this organism available to the public. This forms a formidable obstacle to exploiting this organism for further study. Many results could not be clearly elucidated due to the lack of knowledge of the alteration induced by xenobiotics on the level of gene transcription and protein expression prior to the endpoint effects, on account of the scarcity of genetic resources. Here, we applied expressed sequences tag (EST) analysis to characterize the gene expression profile of liver of rare minnow. Besides, given that rare minnow is a newly developed species for chemical toxic test, the genes involved in absorption, transportation, biotransformation, metabolism of xenobiotics and adaptive responses elicited by chemicals are of great value. Thus, we attempted to compile a potential toxicological catalog recruiting the genes that are involved in the toxicological Available online at www.sciencedirect.com Comparative Biochemistry and Physiology, Part D 2 (2007) 356 – 362 www.elsevier.com/locate/cbpd ⁎ Corresponding author. Tel.: +86 10 64807185; fax: +86 10 64807099. E-mail address: daijy@ioz.ac.cn (J. Dai). 1744-117X/$ - see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.cbd.2007.09.002