The present study successfully utilizes a new ADME Rat Expression Bioarray, containing 1040 metabolism-and toxicology-linked genes, to monitor gene expression from the livers of rats treated with carbon tetrachloride (CCl 4 ). Histopathological analysis, hierarchical clustering methods, and gene expression profiling are compared between the control and CCl 4 -treated animals. A total of 44 transcripts were found to be altered in response to the hepatotoxin, 19 of which were upregulated and 25 were downregulated. Some of these gene expression changes were expected and concurred with previously published data while others were novel findings.

We have developed a unique methodology for the combined analysis of histomorphometric and gene-expression profiles amenable to intensive data mining and multisample comparison for a comprehensive approach to toxicology. This hybrid technology, termed extensible morphometric relational gene-expression analysis (EMeRGE), is applied in a toxicological study of time-varied vehicle-and carbon-tetrachloride (CCl 4 )-treated rats, and demonstrates correlations between specific genes and tissue structures that can augment interpretation of biological observations and diagnosis. The electronic version of this article is the complete one and can be found online at

Poster abstracts 53 tion for parallel analysis of sets of target sequences. The method employs arrayed primers that bind specific padlock probes and initiate rolling-circle replication. A localized, linear concatemer is generated that is detected by fluorescence microscopy in a microarray format. Recently we have shown that padlock probes can also be ligated on RNA template with good sequence discrimination. Therefore, this method may also be suitable for analysis of RNA expression. The ability of padlock probes to detect RNA sequence variation may facilitate the analysis of closely related genes and alternatively spliced transcripts, which have been difficult to study with cDNA-based expression arrays. The inherent signal amplification will aid in quantitation of low-abundance RNA, and may expand the use of expression arrays by permitting the study of small cell populations such as developing tissues and solid tumours. Iyer, Vishy