Molecular responses caused by the combination of pesticide exposure and immunological challenge in Broad-snouted caiman

POLETTA, GISELA; EVELYN CECILIA LOPEZ GONZALEZ; MARIA VIRGINIA PARACHÚ MARCÓ; KROLL, KEVIN J; SIROSKI, PABLO ARIEL; DENSLOW, NANCY D.

Nashville

Congreso; 62nd Annual Meeting and ToxExpo Nashville; 2023

Toxicogenomics is an emerging field of science that combines toxicology and genomics knowledge, especially using high throughput molecular profiling technologies, such as Transcriptomics. The principle idea underlying toxicogenomics is that alterations in conventional toxicological parameters are accompanied by gene expression changes. The analysis of expressed genes in a tissue at the mRNA level provides much increased insight into biologicalprocesses at the molecular level. The aim of this study was to analyze gene expression profiles of blood samples obtained from juvenile Caiman latirostris after acute exposure to a cypermethrin-based pesticide formulation and immune challenge with Escherichia coli. Eight juvenile caiman were separated in two experimental groups: a negative control (C) and a group exposed (E) to the cypermethrin formulation Atanor® (25% a.i.). Animals were maintained under controlled conditions in plastics containers and the exposure was performed by voluntary immersion in water, at a concentration of 2 µg/l during 15 days. After exposure, all animals were immunologically challenged by an injection with E. coli suspension (absorbance: 0.5, ~ 1.5 x 108 CFU/ml) at a dose of 0.1 ml/kg during 96 h. Blood samples were taken from all animals at the beginning and at the end of the experiment and immediately preserved in TRIzol®reagent-LiqN2. RNA extraction from whole blood was conducted following a protocol previously adapted for the species. Libraries were prepared (cDNA 0.1-5.0 μg) and cDNA was sequenced using Illumina sequencing Technology (NGS) through a Hiseq3000 instrument. We identified 1266 differentially expressed genes in caiman challenged only by E. coli: 489 (38.6%) downregulated (DR) and 777 (61.4 %) upregulated (UR). When we analyze animals previously exposed to CYP, the number of genes differentially expressed decreased to 592, of which 248 (41.9%) were DR and 344 (58.1%) UR. These results suggestthat the previous exposure of caiman to CYP caused a decrease in the immune response of the animals. Functional analysis identified different affected metabolic pathways with possible consequences in important biological processes, including lipid and carbohydrate metabolism (synthesis and degradation), immune response (cytokines, interleukins, tumor necrotic factor), oxidative damage and cell adhesion function, allowing the development of new molecular biomarkers through the expression analysis of genes related to these pathways.