6. Effects of the beta-blocker propranolol on health status and gene regulation in the mussel, Mytilus galloprovincialis E. Fabbri, S. Franzellitti (University of Bologna, Italy); A. Capuzzo (University of Ferrara, Italy) Pharmaceuticals and personal care products (PPCPs) are ubiquitous emerging contaminants in the environment. Although acute toxicity toward aquatic organisms is relatively low, many studies agree that chronic exposure and more specific endpoints should be used in pharmaceutical risk assessment. Furthermore, the identification of modes of toxic action exerted on non-target organisms is a crucial step in assessing the effect of pharmaceuticals. In the present study, we evaluated the possible toxicity of propranolol in mussels, Mytilus galloprovincialis, exposed for 7 days to the compound at environmentally relevant concentrations (0.3 and 30 μg/L). Propranolol is a well-known beta adrenergic receptor-blocker widely used for cardiovascular diseases therapy, acting also as a serotonin-receptor antagonist. Different endpoints were evaluated: a) lysosome membrane stability as a highly sensitive biomarker indication of the cell health status; b) PKA activity, since this enzyme is involved in the transduction pathways coupled to beta adrenergic- and serotonin-receptors; and c) Pgp gene expression, an ABC transporter related both to the PKA-mediated regulatory pathway as well as to the cytoprotective response towards xenobiotics. Lysosome membrane stability of mussel haemocytes was significantly lowered (up to -60% vs controls) after a 7-day exposure to propranolol. PKA activity was significantly increased in the mantle, while unaffected in the gills. In the same experimental conditions, a significant up-regulation of the Pgp transcript was detected in the mantle. On the whole, our data indicated that propranolol caused the development of a stress syndrome and alteration of regulatory pathways, possibly interfering with physiological and stress response mechanisms in mussels. doi:10.1016/j.cbpa.2009.05.053 7. Closing the gap between transcriptomics and physiology D. Knapen, R. Blust (University of Antwerp, Belgium) Transcriptomics, the analysis of gene expression patterns, has become a highly popular means of studying responses of organisms to toxicants and other types of stress. Although our understanding of the mechanisms underlying stress responses still remains fragmentary, new insights into these mechanisms have been provided by focusing on the transcriptional level. The idea that gene expression data would lead to the unraveling of underlying molecular mechanisms, which would subsequently offer a direct explanation for effects observed at higher levels of biological organisation, has long been the central dogma of the transcriptomics approach, and of a systems biology approach in general. However, as technology progresses and many thousands of genes can now be studied simultaneously leading to highly complex datasets, and as more and more transciptomics data are being published, it has become clear that the true biological significance of altered expression of one or more genes is difficult to comprehend. The current work analyses and reviews published studies that try to close the gap between transciptomics and its real physiological significance. Transcriptomics data should probably be approached differently from what is often the case today if one aims at truly integrating such data with higher-level information. The potential of new analytical and statistical techniques developed for this purpose, such as functional module discovery, is critically examined. doi:10.1016/j.cbpa.2009.05.054 8. Metal-induced death in fish cells: Signalling pathways and mechanisms G. Krumschnabel, C. Manzl, H.L. Ebner (Medical University Innsbruck, Austria) Environmental contaminants, including various metals at supra- physiological levels, exert toxic effects on fish and other aquatic organisms, both at the systemic and at the cell level. In order to elucidate the mechanisms underlying cellular effects induced by the environmentally important metals copper and cadmium, specifically focusing on the pathways leading to cell death and the mode of death triggered, in vitro studies using primary cells and cell lines from fish were conducted. Previous studies showed that acute cadmium toxicity is relatively minor, whereas copper causes either necrotic or apoptotic cell death, depending on the dose applied. Further, while cadmium affected neither metabolism nor ion homeostasis, copper caused a massive calcium-influx, calcium-dependent disturbance of energy metabolism, affected hormonal responsiveness, and induced radical-stress. The latter originated primarily form mitochondria and lysosomal compartments and was critically involved in opening of the cyclosporine-A-sensitive mitochondrial permeability transition pore. Upstream signalling pathways activated by copper appeared to involve mitogen-activated protein kinases, the selective inhibition of which reduced radical formation (ERK, p38), caspase activation (ERK, p38, JNK), and necrosis (ERK, p38). Additional experiments address the question of whether copper toxicity in fish cells also triggers the DNA damage response pathway, as known from mammalian cell models (p-ATM, gamma-H2AX, 53BP-1), and if apoptosis is asso- ciated with Bax-activation and mitochondrial translocation, and ultimately with mitochondrial outer membrane permeabilization (MOMP). doi:10.1016/j.cbpa.2009.05.055 9. Biomphalaria glabrata embryonic cells as a model system for toxicological and molecular studies of stress-induced expression of metallothionen genes D. Schuler, M. Höckner, A. Prader, R. Dallinger (University of Innsbruck, Austria) Biomphalaria glabrata is a widespread freshwater gastropod mollusk. Like other gastropod species, these animals possess efficient capabilities for dealing with environmental stress includ- ing metal exposure, for which efficient mechanisms have been evolved aiming at inactivating toxic metal ions. It has been shown that in terrestrial helicids, for example, a Cd-inducible Metallothio- nein isoform (Cd-MT) plays an important role in such detoxifying processes. In our current work we identified three different MT isoforms at the mRNA level from individual midgut glands of Biomphalaria glabrata, kept in freshwater tanks. In addition, we used Biomphalaria glabrata embryonic cells (Bge cells) as a model system for metal exposure, MT induction, and MT construct transfection experiments. We could show that Cd-exposed Bge cells were about 20-times less susceptible towards Cd 2+ ions compared to a NIH/3T2 mouse cell line. All three MT isoforms previously isolated from living individuals of Biomphalaria glabrata could also be detected in the Bge cells, including a Cd-specific isoform. PCR amplification and quantification of this isoform showed a significantly increased transcription of the Cd-MT gene in Cd-treated cells compared to untreated ones. We suggest that Abstracts / Comparative Biochemistry and Physiology, Part A 154 (2009) S13–S22 S15