Expression patterns of Cytochrome P4501A gene induced by environmental conditions and glucocorticoid response elements (GRE) in wild fish lagoon Fundulus species

Several species of the genus Fundulus survive in environments highly impacted by human activities. When fish are exposed to environmental stress conditions, the expression of enzyme cytochrome P4501A is induced. The capacity of fish to adapt to environmental conditions could influence their survival and distribution. We evaluate the gene expression of CYP4501A in two endemic Fundulus species from Chelem Lagoon (22 individuals of Fundulus grandissimus and 31 of Fundulus persimilis ) and Carbonera Lagoon (12 individuals of F. persimilis ), both located in the north coast of the Yucatan Peninsula. Individuals of F. grandissmus exhibit higher expression values compared to F. persimilis. A statistically significant difference was detected in CYP4501A gene expression between populations of F. persimilis in Chelem Lagoon and between lagoons, possibly induced by environmental conditions. We also found Glucocorticoid Response Elements (GRE) in the sequences of the regulatory region of the CYP4501A gene. GRE act as glucocorticoid recognition sites, which regulate the expression of CYP enzymes. F. grandissimus individuals with higher expression levels exhibit a mutation in a GRE site, affecting the regulation of CYP enzymes inducing overexpression. Our results suggest that gene expression of CYP enzymes is induced by environmental conditions and also affects the function of their regulatory GRE sites.