# Molecular Cloning and Characterization of Estrogen-Related Receptor Gene in Corbicula fluminea: Expression Profiles in Response to Bisphenol A and Its Substitutes Exposure

## TL;DR

This study cloned and analyzed an estrogen-related receptor gene in a freshwater mussel, finding that it responds to endocrine-disrupting chemicals like BPA and its substitutes.

## Contribution

The first characterization of the ERR gene in Corbicula fluminea and its response to bisphenol exposure in mollusks.

## Key findings

- The CfERR gene is highly expressed in the gonad, indicating a role in reproductive regulation.
- Exposure to BPA and its substitutes upregulates CfERR expression in a time- and dose-dependent manner.
- BPS and BPAF showed stronger estrogenic interference effects compared to BPA.

## Abstract

Bisphenol A (BPA) and its alternatives have been identified as endocrine-disrupting chemicals (EDCs), yet there is a paucity of research data regarding their reproductive disrupting effects on mollusks. In this study, we successfully cloned the full length of the estrogen-related receptor (ERR) gene from Corbicula fluminea (CfERR) by RACE technology. Subsequently, we conducted bioinformatics analysis and tissue-specific expression analysis of CfERR. Additionally, we examined the expression profiles of the CfERR gene following 28-day exposure to 1, 10, and 100 μg/L concentrations of 17β-estradiol (E2), BPA, and its substitutes (bisphenol S (BPS), bisphenol F (BPF), and bisphenol AF (BPAF)). Sequence alignment revealed that the CfERR showed high homology with those of other bivalve mollusks. Tissue expression analysis demonstrated that the CfERR gene exhibited the highest expression level in the gonad. Results from the exposure experiment indicated that the expression of CfERR was upregulated under the stress of all tested pollutants. This study provided a scientific basis for the conservation of shellfish germplasm resources, laying a foundation for investigating the reproductive regulation mechanism of bivalve mollusks and offering important data support for the toxic assessment of BPA and its alternatives.

Bisphenol A (BPA) and its substitutes have been identified as endocrine-disrupting chemicals (EDCs). However, little information is available on their reproductive endocrine disruptive effects in mollusks. This study cloned the full-length sequence (2434 bp) of the estrogen-related receptor (ERR) gene in the freshwater bivalve Corbicula fluminea and performed a bioinformatics analysis and tissue-specific expression analysis. We further examined the expression of the CfERR gene after exposure to E2, BPA, and their substitutes (BPS, BPF, and BPAF) at 1, 10, and 100 μg/L for 0, 1, 7, 14, 21, and 28 days. The results showed that CfERR is a nuclear protein with a typical structure. Phylogenetic analysis indicated a high degree of similarity among bivalve species. The high expression of CfERR in the gonad suggested its important role in reproductive regulation. The exposure experiment confirmed that CfERR showed a time- and dose-dependent upregulation in response to all pollutants, with BPS and BPAF exhibiting stronger estrogenic interference effects. This study facilitates a better understanding of the reproductive regulation of bivalves and provides data to support the toxicity evaluation of BPA and its substitutes.