Searching for toxic mechanisms and synergistic effects of synthetic and natural organophosphates in Oreochromis niloticus (Cichlidae) and Danio rerio (Cyprinidae)

• Grant number: 23/01033-1
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: February 01, 2024
• End date: January 31, 2025
• Field of knowledge: Biological Sciences - Pharmacology - Toxicology
• Principal Investigator: Ernani Pinto Junior
• Grantee: Larissa Souza Passos
• Supervisor: Colette Vom Berg
• Host Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Institution abroad: EAWAG - Swiss Federal Institute for Aquatic Science and Technology, Dübendorf, Switzerland
• Associated to the scholarship: 21/14239-1 - Effects of interaction between synthetic and natural organophosphates on Oreochromis niloticus (Teleostei: Cichlidae), BP.DR

Abstract

This study aims to evaluate the toxicity of a natural organophosphate (guanitoxin), produced by the cyanobacterial strain ITEP-024 (Sphaerospermopsis torques-reginae), combined with synthetic organophosphates (malathion and trichlorfon) in specimens of Oreochromis niloticus and Danio rerio. The hypothesis is that the association of these compounds will cause additive/synergistic effects (e.g., molecular damage) in these animals. First, O. niloticus specimens will be exposed for 96 hours to the insecticide's malathion (1 mg/L) and trichlorfon (0.5 mg/L) and cyanobacterial extracts of guanitoxin of the strain ITEP-024 (250 mg/L - dry weight biomass) separately and combined. Then, the following combinations will be studied: ITEP-024 + malathion, ITEP-024 + trichlorfon, and ITEP-024 + malathion + trichlorfon. The D. rerio assays will be performed in the early life stages of the embryos (Fish Embryo Toxicity test - FET), following OECD guideline number 236 (2013). Embryos will be exposed to malathion, trichlorfon, and ITEP-024 extracts, separately and combined, for 120 hours (final concentrations still need to be defined). For both species, the expression of genes related to acetylcholine neurotransmission will be quantified by quantitative real-time PCR. For D. rerio, skeletal muscle integrity, neurotoxicity, morphological, cardiovascular, and behavioral changes will be assessed. We expect to contribute to understanding the toxicological potential of natural and synthetic organophosphates present in freshwater environments and their effects and interaction with fish. (AU)