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Gen Comp Endocrinol 2010 Apr 01;1662:428-35. doi: 10.1016/j.ygcen.2009.12.008.
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Expression and T3 regulation of thyroid hormone- and sex steroid-related genes during Silurana (Xenopus) tropicalis early development.

Duarte-Guterman P , Langlois VS , Pauli BD , Trudeau VL .

In amphibians, thyroid hormones (THs) are the primary regulators of metamorphosis; however, their physiological role during embryogenesis remains unclear. First, we established complete developmental profiles for TH receptors (tr alpha and tr beta), deiodinases (dio; types 1, 2, 3), estrogen receptors (er alpha and er beta) and androgen receptor (ar) mRNA levels during embryogenesis and early larval stages in Silurana (Xenopus) tropicalis (from Nieuwkoop and Faber (NF) stage 2 until NF 46). Real-time RT-PCR analyses in whole embryos and larvae revealed that all transcripts except tr alpha were detected throughout development; tr alpha only appears after gastrulation. The first significant increase in the expression of tralpha and tr beta was observed before hatching, between NF 21 and NF 27 (2.5- and 11-fold, respectively). In order to test if these genes could be regulated by THs during early larval development, embryos were exposed to triiodothyronine (T3; 0.5, 5.0, 50 nM) from NF 27 to NF 46. T3 exposure caused a dose-dependent increase relative to control in the expression of tr alpha, tr beta, dio (types 2 and 3), ar, and 5 alpha-reductase type 1 in whole larvae. These results indicate that in S. tropicalis, tr and dio can be induced by T3 as early as NF 46, a response that had only been characterized later during frog metamorphosis. In addition, T3 also affected androgen-related gene expression, supporting our hypothesis that THs are involved in male development in frogs.

PubMed ID: 20015451
Article link: Gen Comp Endocrinol

Species referenced: Xenopus tropicalis
Genes referenced: ar cyp19a1 dio1 dio2 dio3 esr1 esr2 odc1 rpl8 srd5a1 srd5a2 thra thrb

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