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- Sea bream (Sparus auratus) estrogen receptors: phylogeny and tissue distributionPublication . Pinto, Patricia IS; Passos, A. L.; Power, Deborah; Canario, Adelino V. M.Most estrogen actions are mediated by two estrogen receptor subtypes (ER and ER ). While a single ER appears to be present in higher vertebrates, two forms of ER encoded by different genes have recently been isolated in some teleost fish species. We investigated whether this also applies to the hermaphrodite sparid sea bream (Sparus auratus) and cloned a second ER (sbER 2) in this species. We have also compared the tissue distribution of the three receptors as yet identified in sea bream, designated sbER , sbER 1, and sbER 2.
- Immunohistochemical detection of estrogen receptors in fish scalesPublication . Pinto, Patricia IS; Estêvão, M. Dulce; Redruello, Begoña; Socorro, S.; Canario, Adelino V. M.; Power, DeborahCalcium mobilization from internal stores, such as scales, induced by 17b-estradiol during sexual maturation in salmonids is well documented. This calcium mobilization from scales is proposed to be mediated by the estrogen receptor (ER). However, the ER subtypes involved and signaling mechanisms responsible for this effect remain to be fully characterized. In the present study, we have localized ERa, ERba and ERbb proteins in juvenile and adult sea bream (Sparus auratus) and Mozambique tilapia (Oreochromis mossambicus) scales by immunohistochemistry with sea bream ER subtype specific antibodies. The three ERs were detected in isolated or small groups of round cells, in the basal layer of the scales of both juvenile and adult fish and the localization and signal intensity varied with the species and age of the animals. The ERs may be co-localized in cells of the scale posterior region that expressed tartrateresistant acid phosphatase (TRAP), a marker for osteoclasts. These results suggest that the calcium mobilizing action of 17b-estradiol on fish scales is via its direct action on ERs localized in osteoclasts.
- A yeast assay based on the gilthead sea bream (teleost fish) estrogen receptor ß for monitoring estrogen mimicsPublication . Passos, A. L.; Pinto, Patricia IS; Power, Deborah; Canario, Adelino V. M.A yeast(Saccharomyces cerevisiae)-based assay was developed and tested with steroids and chemicals (mostly pesticides). The induction of b-galactosidase activity was strictly dependent on the presence of seabream (Sparus aurata) ba estrogen receptor(sbERba) and substances known to have estrogenic activity. 17b-Estradiol (E2) and diethylstilbestrol(DES), both agonists, were most active and the antagonist tamoxifen(TAM)was14-fold less active than E2. Among the chemicals tested bisphenol-A was most active, followed by pentachlorophenol and naphthalene. Ligand-binding assays with recombinant sbERba and sbERa revealed that sbERba binds E2 with 6.5-fold higher affinity than sbERa, confirming the selection of a high sensitive receptor for the yeast assay. DES, ICI182, 780,estrone and TAM had higher relative binding affinity to E2 in sbERa than sbERba, although there was no difference in IC50 for these steroids between the two receptors. These results reveal the use fulness of using they east-based receptor assay for detecting chemical interaction with steroid receptors from contaminated samples.