Multiple biomarkers response of Oreochromis niloticus (Teleostei: Cichlidae) exposed to a guanitoxin-producing cyanobacterial strain

Author(s)

Larissa Souza Passos

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ)
• Defense date: 2022-01-28

Examining board members

Ernani Pinto; Rafael Mendonça Duarte; Adriana Regina Chippari Gomes; Levi Pompermayer Machado

• Advisor: Ernani Pinto

Abstract

Changes in environmental conditions in aquatic ecosystems caused by anthropic actions can modify the composition of primary producers, promoting the excessive proliferation of cyanobacteria. These organisms can form cyanobacterial blooms, which directly affect aquatic life. The present study investigated the mutagenicity of the cyanobacterium Sphaerospermopsis torques-reginae (strain ITEP-024) guanitoxin-producing (natural organophosphate) and sublethal effects on fish in relevant environment concentrations. For this, Ames test (Salmonella/microsome) was performed as a mutagenic assay for extracts of ITEP-024 strain. Specimens of Oreochromis niloticus (Teleostei: Cichlidae) were subjected to acute 96-hour exposure to different concentrations of aqueous extract of the strain: C = control group; T1 = 31.25 mg L-1; T2 = 62.5 mg L-1; T3 = 125 mg L-1, and T4 = 250 mg L-1. Genotoxic, biochemical, osmoregulatory, and physiologic biomarkers were analyzed. Our results showed that the cyanobacterium had a weak mutagenic response for TA102 strain of Salmonella with and without metabolic activation by S9. Strains TA98 and TA100 were not affected. Fish from treatments T3 and T4 showed changes in oxidative stress (CAT, SOD, and GST enzymes), inhibition of the enzyme AChE activity, micronucleus formation, and osmoregulatory disorders. No guanitoxin accumulation was detected in the different tissues of O. niloticus by LC-MS/MS. Our results showed unprecedented mutagenicity data of the cyanobacteria guanitoxin-producing by Ames test and biochemical, osmoregulatory, and genotoxic disorders in fish, providing efficient aquatic contamination biomarkers. Despite the great concern related to the presence of guanitoxin in blooms in freshwater ecosystems, there is no monitoring, and its concentration is not yet regulated. (AU)

• FAPESP's process: 20/00109-6 - Cyanopeptide toxicity assessment in fish for human consumption from artificial ponds
• Grantee: Larissa Souza Passos
• Support Opportunities: Scholarships in Brazil - Master