A estradiol‐17β receptor in the reproductive system of the female of Octopus vulgaris: Characterization and immunolocalization

Abstract In this study, for the first time we have identified an estradiol‐17β receptor (ER) in the reproductive system of the female of Octopus vulgaris . Scatchard analysis revealed that one binding component with high affinity and low capacity for the ligand was present in the cytosol, but not in the nuclear extract of the ovary and the oviduct. A steroid specificity competition assay showed that 3 H‐estradiol‐17β binding activity showed a preference for estradiol‐17β. DNA‐cellulose chromatography confirmed the presence of one 3 H‐estradiol‐17β binding component. By using antibodies anti ER (578‐595), we have localized by Western blotting one band of about 70 kDa. ER immunoreactivity has been localized in the nuclei of the follicle cells of the ovary, in the nuclei of the epithelium lining the proximal portion of the oviduct and in the nuclei, and in the cytoplasm of the inner region of the oviducal gland and in the cytoplasm of the outer region of the oviducal gland. These data, taken together, provide evidence that in Octopus vulgaris the ER has biochemical and immunohistochemical characteristics resembling those of ER in vertebrates.Mol. Reprod. Dev. 61: 367–375, 2002. © 2002 Wiley‐Liss, Inc.