Name: | Description: | Size: | Format: | |
---|---|---|---|---|
6.9 MB | Adobe PDF |
Authors
Advisor(s)
Abstract(s)
Two estrogen receptor subtypes (ERα and ERβ) mediate most estrogen actions in
vertebrates, including fishes. Furthermore in teleost fishes two ERβ genes are
differentially expressed. In this thesis, an ERβ (sbERβb) was cloned from the
hermaphrodite teleost fish sea bream (Sparus auratus) which added to the previously
cloned sbERα and sbERβa. sbERβb specifically binds estrogen agonists and antagonists
with high affinity. The three sbER genes (α, βa, βb) have a partially overlapping but
differential distribution in male and female sea bream tissues and produce multiple
transcripts. Two exon2 deleted sbERα variants were also identified with different tissue
distribution and hormonal regulation.
Estradiol-17β up-regulated the expression of sbERα and down-regulated both sbERβs in
liver, suggesting a major role for ERα in vitellogenesis. Agonistic effects were identified
for the “pure antiestrogen” ICI 182,780 in several estrogenic responses, probably
mediated by sbERα up regulation in liver. The immunolocalization of sbER proteins in
sea bream scales suggested that the calcium mobilising actions of E2 in scales are via a
direct action on osteoclasts. Subtractive hybridization followed by RT-PCR demonstrated
for the first time in fish testis the E2 up regulation of some typical liver E2-induced genes
(e.g. vitellogenins and choriogenins).
Description
Tese dout., Biologia, Universidade do Algarve, 2006
Keywords
Teses Biologia molecular Estradiol Estrogénios Teleósteos Antiestrogénio Disrupção endócrina