Freshwater snail Parafossarulus striatulus estrogen receptor: Characteristics and expression profiles under lab and...

The modes of action by which putative endocrine disrupting chemicals (EDCs) elicit toxicity in mollusks remains unclear due to our limited understanding of the molluscan endocrine system. We identified and partially characterised the estrogen receptor (ER) of the mollusk Parafossarulus striatulus. The full-length cDNA of the ER of P. striatulus (psER) was isolated and found to have an ORF of 1386 bp which corresponded to 461 amino acids. Phylogenetic analysis revealed that psER is an orthologue of ER of other mollusks. Moreover, the DNA-binding domain, ligand-binding domain, P-box, D-box, and AF2 domain were also identified in psER. Exposure of females and males to 17β-estradiol (E2, 100 ng/L) for 24 h and 72 h did not alter psER transcription, but exposure to 17α-methyltestosterone (MT, 100 μg/L) for 72 h significantly decreased ER transcription in females only (p < 0.05). psER transcription was surveyed in males and females seeded in different regions in Taihu Lake, China. psER transcription were elevated among females and males maintained at site ML. This elevation was statistically significant (p < 0.05) among male snails as compared to snails held at the more pristine site of SZ. This was different to the results from lab, implying that some unknown chemicals or other environmental factors in field could affect psER transcription level in snails. Furthermore, females and males held at site ML also exhibited a significant elevation in vitellogenin transcription as compared to snails held at site SZ, suggesting that vitellogenin production may be directly regulated by psER or co-regulated with psER in this species.