Percorrer por autor "Passos, A. L."
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- Characterization of estrogen receptor ßb in sea bream (Sparus auratus): phylogeny, ligand-binding, and comparative analysis of expressionPublication . Pinto, Patricia IS; Passos, A. L.; Martins, Rute S. T.; Power, Deborah; Canario, Adelino V. M.Estrogens control many physiological processes in both female and male vertebrates, mostly mediated by speciWc nuclear estrogen receptors (ER). Two ER subtypes (ER and ER ) are present in most vertebrates, including the sea bream (Sparus auratus) a hermaphrodite teleost Wsh. In the present study several variant cDNAs encoding a second sea bream ER (sbER b) is reported. Phylogenetic and Southern blot analysis indicate that sbER b and the previously cloned sbER a (formerly sbER ) are encoded by diVerent genes, which may have arisen by duplication of an ancestral ER gene. Competitive binding assays show that sbER b has high aYnity for 17 -estradiol (KdD1 nM) and speciWcally binds estrogen agonists (diethylstilbestrol and ethynylestradiol) and antagonists (ICI 182,780). In Northern blot sbER , sbER a, sbER b produce several diVerent transcripts in a variety of tissues. RT-PCR showed a partially overlapping but diVerential tissue distribution in both male and female sea bream.
- Isolation of a novel aquaglyceroporin from a marine teleost (Sparus auratus) Function and tissue distributionPublication . Santos, C. R. A.; Estêvão, Dulce; Fuentes, J.; Cardoso, João CR; Fabra, Mercedes; Passos, A. L.; Detmers, F. J.; Deen, P. M. T.; Cerda, J.; Power, DeborahThe aquaporins (formerly called the major intrinsic protein family) are transmembrane channel proteins. The family includes the CHIP group, which are functionally characterised as water channels and the GLP group, which are specialised for glycerol transport. The present study reports the identification and characterisation of a novel GLP family member in a teleost fish, the sea bream Sparus auratus. A sea bream aquaporin (sbAQP) cDNA of 1047·bp and encoding a protein of 298·amino acids was isolated from a kidney cDNA library. Functional characterization of the sbAQP using a Xenopus oocyte assay revealed that the isolated cDNA stimulated osmotic water permeability in a mercury-sensitive manner and also stimulated urea and glycerol uptake. Northern blotting demonstrated that sbAQP was expressed at high levels in the posterior region of the gut, where two transcripts were identified (1.6·kb and 2·kb), and in kidney, where a single transcript was present (2·kb). In situ hybridisation studies with a sbAQP riboprobe revealed its presence in the lamina propria and smooth muscle layer of the posterior region of the gut and in epithelial cells of some kidney tubules. sbAQP was also present in putative chloride cells of the gill. Phylogenetic analysis of sbAQP, including putative GLP genes from Fugu rubripes, revealed that it did not group with any of the previously isolated vertebrate GLPs and instead formed a separate group, suggesting that it may be a novel GLP member.
- 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.
- Transcriptome analysis of the gilthead sea bream (sparus auratus) pituitary gland. Type I markers for molecular geneticsPublication . Louro, Bruno; Passos, A. L.; Power, DeborahThe pituitary gland of vertebrates produces a number of hormones, growth hormone, prolactin, somatolactin, gonadotrophin, thyroid stimulating hormone, proopiomelanocorticotrophin, which regulate a number of important production traits.
- 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.