EMBRYOTOXICITY OF DICLOFENAC ON DANIO RERIO: MORTALITY, MORPHOLOGICAL ALTERATIONS AND TRANSCRIPTOME-WIDE SCALE TOXICITY ASSESSMENT Lancieri M.*, Chiarelli G.*,De Felice B,** Lombardo M.* and Guida M.* *Department of Biological Sciences, University of Naples “Federico II” , Via Mezzocannone 8, 80134 Napoli, Italy e-mail lancieri @unina.it ** Department of Life Sciences, University of Naples II, Via Vivaldi 43, 81100 Caserta, Italy Diclofenac, 2-[(2,6-dichlorophenyl)amino]phenylacetic acid is a non-steroidal anti-infiammatory drug (NSAID) taken to reduce inflammation and as an analgesic reducing pain in conditions such as arthritis or acute injury. It can also be used to reduce menstrual pain, dysmenorrhea. The name is derived from its chemical name: 2-(2,6-dichloranilino) phenylacetic acid. The primary mechanism responsible for its antiinflammatory / antipyretic / analgesic action is inhibition of prostagladin synthesis by blocking cyclooxygenase (COX). Pollution from drugs is an emergent problem (Comoretto et al., 2005) because they are continually released in the environment. It is seemed important to study the embryo toxic effects of diclofenac for his numerous and serious side effects on humans, leading to heart, liver, kidney, gastrointestinal and hematological damages. To assess the ecotoxicity of Diclofenac, Danio rerio (zebrafish) embryos tests can be useful (Lancieri et al., 2004). Acute toxicity test. In these tests, the embryos were left to develop in the presence of Diclofenac to different concentrations, from 0.3 to 320mg / L, for 144 hours. Every 24 hours, the embryos were observed and the number of malformed and dead was counted. At 0.6 mg / L Diclofenac concentration, about 60% of malformed embryos were counted after 48h of development. This number rises to 100% at Diclofenac concentration of 1.25 mg / L. The most common morphological alterations include: a bending of the body axis, possibly consequent of the very poor development of the musculature; unilateral anomalies in eye development and a significant disorganization of gastro-intestinal and cardiac systems. These malformations led to death of embryos after 144h of development from fertilization. With increasing of Diclofenac concentration, the damages became increasingly severe and the survival times shorter, until to obtain fatality rate of nearly 100% in the first 24 hours of development, at Diclofenac concentration of 80mg / L. Beside, we have studied the effect of diclofenac polluted waters on zebrafish embryos on a transcriptome-wide scale. To reveal the molecular mechanism leading to the toxic effects, the technique of mRNA differential display was applied to the detection of RNAs induced in zebrafish embryos undergoing neogenesis following toxicant- induced injury. Our studies clearly indicate that the use and consequent release of diclofenac in the environment may cause considerable environmental damages. References Comoretto L. and Chiorn S. Comparing pharmaceutical and pesticide loads into a small Mediterranean river. Science of Total Envroment 2005; 349: 201-210. Lancieri M., Aniello F., Esposito D:, Migliore L. and Gaudio L. Embryotoxicity of flumequine on Danio rerio: mortality, morphological/histological alterations and changes in calmodulin gene expression 2004;13:1415-1419.