Chemico-Biological Interactions 169 (2007) 171–188 Induction of biochemical stress markers and apoptosis in transgenic Drosophila melanogaster against complex chemical mixtures: Role of reactive oxygen species Hifzur R. Siddique a , Subash C. Gupta a,1 , Kalyan Mitra c , Ramesh C. Murthy b , Daya K. Saxena a , Debapratim K. Chowdhuri a,∗ a Embryotoxicology Section, Industrial Toxicology Research Centre, P.O. Box No. 80, M.G. Marg, Lucknow 226 001, Uttar Pradesh, India b Metal Analysis Section, Industrial Toxicology Research Centre, P.O. Box No. 80, M.G. Marg, Lucknow 226 001, Uttar Pradesh, India c Electron Microscopy Unit, Central Drug Research Institute, Chattar Manzil, M.G. Marg, Lucknow 226 001, Uttar Pradesh, India Received 18 April 2007; received in revised form 31 May 2007; accepted 12 June 2007 Available online 20 June 2007 Abstract The study was aimed to investigate the effect of leachates of solid waste from a flashlight battery factory and a pigment plant on 70 kDa heat shock protein (Hsp70) expression, generation of reactive oxygen species (ROS), antioxidant enzymes activities and apoptosis in Drosophila. Third instar larvae of Drosophila melanogaster transgenic for hsp70 (hsp70-lacZ) were fed on diet mixed with leachates of solid wastes (0.05–2.0%, v/v) released from two industrial plants at three different pHs (7.00, 4.93 and 2.88) for 2–48 h. A concentration- and time-dependent significant change in Hsp70 expression, ROS generation, antioxidant enzymes activities and MDA content was observed in the exposed larvae preceding the antioxidant enzymes activities. Mitochondria-mediated, caspase-dependent apoptotic cell death in the larvae exposed to 1.0 and 2.0% leachates of flashlight battery factory was concurrent with a significant regression in Hsp70 expression and a higher ROS generation. A positive correlation drawn between ROS generation and apoptotic markers and a negative correlation between apoptotic markers and Hsp70 expression in these groups indicated the important role of ROS in the leachate-induced cellular damage. Hsp70 along with antioxidant enzymes offered protection to the organisms exposed to all the tested concentrations of the leachates of pigment plant waste and 0.5% leachate of flashlight battery factory in a cooperative manner when ROS generation was less induced. Conversely, higher levels of ROS generation in the organisms treated with 1.0 and 2.0% leachate of flashlight battery factory after 24 and 48 h resulted in regression of Hsp70 expression in them leading to cell death. The study suggests that (1) leachates of flashlight battery factory waste more adversely affected the organisms in comparison to the leachates of pigment plant waste. (2) Hsp70 may be used as a biomarker of cellular damage in organisms exposed to leachates. (3) Cell based assays using D. melanogaster as an in vivo model may provide important mechanistic information about the adverse effect of xenobiotics. © 2007 Elsevier Ireland Ltd. All rights reserved. Keywords: Leachates; ROS; Hsp70; Antioxidant enzymes; LPO; Apoptosis ∗ Corresponding author. Tel.: +91 522 2620207x219; fax: +91 522 2628227. E-mail address: dkarchowdhuri@rediffmail.com (D.K. Chowdhuri). 1 Present address: Central Fuel Research Institute, Dhanbad 828 108, India. 0009-2797/$ – see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.cbi.2007.06.035