The presence of 17-beta estradiol in Mytilus edulis gonadal tissues: evidence for estradiol isoforms.

OBJECTIVES: In earlier studies, we demonstrate that 17-β -estradiol and an estrogen cell surface receptor can be found on various human cells, i.e., vascular endothelial, monocytes, and granulocytes, where they are coupled to nitric oxide release. We further demonstrated this phenomenon in the marine mussel Mytilus edulis ganglionic tissues. In the present report we sought to determine if estrogen can be found in M. edulis reproductive tissues. MATERIAL & METHODS: We determined the presence of 17-β -estradiol via high pressure liquid chromatography (HPLC) and radioimmunoassay (RIA) in the animals gonads. This substance was further identifi ed via nanoelectro-spray ionization quadrupole time of fl ight mass spectrometry (Q-TOF-MS). RESULTS: 17-β -estradiol was identifi ed and quantifi ed in Mytilus gonads. Interestingly, we also determined that estradiol isoforms also were present in this tissue. CONCLUSION: These data demonstrate that 17-β-estradiol and an estradiol isoform is present in M. edulis gonadal tissues, suggesting that they have functions related to reproduction. This further suggests that estrogen’s association with reproductive activities has a long evolutionary history and that this association began in invertebrates.