A TOXICOGENOMIC APPROACH FOR DEVELOPMENT OF BIOMARKERS OF PESTICIDE EXPOSURE

CESCHIN, DG; MARDIROSIAN, M; PIRES, N; LASCANO, C; VENTURINO, A

Natal

Congreso; 9th Congress of Toxicology in Developing Countries and XIX Congresso Brasileiro de Toxicología.; 2015

Sociedaide Brasileira de Toxicologia

Introduction: Northern Patagonia is an irrigated area holding 95% of exportable production of apple and pear. Around 900 ton/year of pesticides have been applied since year 2000 where 90% correspond to organophosphates. 50% of the pesticides applied are dispersed into the atmosphere without reaching the intended targets and ending mainly in irrigation canals, ponds, streams and rivers. Biomonitoring of environmental impact of pesticides using native species is a preferred resource for its ecological significance. Rhinella arenarum is a toad widely distributed in Argentina and less in Brazil, Bolivia and Uruguay. Organophosphates produce lethal and sublethal organism effects including presence of abnormalities, impaired growth and biochemical effects. In this sense, enzymes and metabolites of detoxification system are widely used as biomarkers. However, many of them are not specific and in several cases not responsive enough. Therefore, it is necessary to develop early, specific and sensitive ecotoxicological biomarkers. Here, we present a high throughput approach (RNA-Seq) to screen new potential biomarkers in R. arenarum larvae exposed to chlorpyrifos (CLP) pesticide.Objective: to develop new biomarkers for chlorpyrifos exposure.Materials and Methods: R. arenarum embryos were obtained by in vitro fertilization. Larvae (complete operculum (CO) + 11 days) were exposed to sublethal concentration of CLP (0.1 mg/L) [96h-LC50 2.5 mg/L)]. Samples were taken at 6h and 24h to evaluate reduced glutathione (GSH) levels and the activities of Glutathione S transferase (GST) and Catalase (CAT). At same time, samples were collected for RNA purification and massive sequencing. Results and discussion: GSH levels and GST and CAT activities were not significantly affected by CLP exposition neither 6h nor 24h compared with control. However, the RNA-Seq profiles showed differences between 6h vs 24h and compared to control. There was a first wave of gene expression at 6h where protein of several of them could drive transcription of genes detected at 24h. As expected, detoxification and oxidative stress pathways were activated. Beside, clustering of genes using Gene Ontology classification showed hits for Biological Process category: development, metabolic and cellular process, among others.