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Expression of enzymes involved in thyroid hormone metabolism during the early development of Xenopus tropicalis

Tindall, A.J., Morris, I.D., Pownall, M.E. and Isaacs, H.V. (2006) Expression of enzymes involved in thyroid hormone metabolism during the early development of Xenopus tropicalis. Biology of the Cell, 99 (3). pp. 151-163. ISSN 0248-4900

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Abstract

BACKGROUND INFORMATION

There are significant indications that amphibians require TH (thyroid hormones) prior to their involvement in the regulation of metamorphosis and before the development of a functional thyroid.

RESULTS.

In order to investigate the potential role for TH in pre-metamorphic Xenopus tropicalis we have cloned cDNAs for, and analysed the expression of, TPO (thyroid peroxidase), 5´DII (type II iodothyronine deiodinase) and 5DIII (type III iodothyronine deiodinase), enzymes involved in TH metabolism. Zygotic expression of TPO was detected in neurula stage embryos. Expression was observed in the notochord and later in the thyroid. The notochord was also a common site of expression for 5´DII and 5DIII. Other sites of 5´DII expression are the otic vesicles, retina, liver, blood-forming region, branchial arches and brain. 5DIII is also expressed in the brain, retina, liver, developing pro-nephros, blood-forming region and branchial arches. Embryos exposed to the TPO inhibitor methimazole showed a distinctive dose-dependent phenotype of a crimped notochord and shortened axis, together with alterations in 125I- uptake.

CONCLUSIONS

These data suggest a novel extrathyroidal role for TH during early development, and support the proposal that embryos require thyroid signalling for normal development prior to metamorphosis.

Item Type: Article
Institution: The University of York
Academic Units: The University of York > Hull York Medical School (York)
Depositing User: York RAE Import
Date Deposited: 14 Aug 2009 09:50
Last Modified: 14 Aug 2009 09:50
Published Version: http://dx.doi.org/10.1042/BC20060074
Status: Published
Publisher: Portland Press
Identification Number: 10.1042/BC20060074
URI: http://eprints.whiterose.ac.uk/id/eprint/5682

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