In ovo thyroxine exposure alters later UVS cone loss in juvenile rainbow trout

Jason C Raine; Allison B Coffin; Craig W Hawryshyn

doi:10.1242/jeb.055566

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In ovo thyroxine exposure alters later UVS cone loss in juvenile rainbow trout

Journal article

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Peer reviewed

In ovo thyroxine exposure alters later UVS cone loss in juvenile rainbow trout

Jason C Raine, Allison B Coffin and Craig W Hawryshyn

Journal of experimental biology, Vol.214(Pt 13), pp.2248-2257

07/01/2011

DOI: https://doi.org/10.1242/jeb.055566

Handle:

https://hdl.handle.net/2376/108135

PMID: 21653819

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Abstract

Oncorhynchus mykiss - metabolism

Thyroid Hormone Receptors beta - metabolism

Down-Regulation

Opsins - biosynthesis

Male

Retina - embryology

Maternal Exposure

Photoreceptor Cells, Vertebrate - physiology

Animals

Gene Expression Regulation, Developmental

Protein Isoforms

Thyroxine - metabolism

Embryo, Nonmammalian

Female

Oncorhynchus mykiss - embryology

Thyroid hormones (THs) play a vital role in vertebrate neural development, and, together with the beta isoform of the thyroid hormone receptor (TRβ), the development and differentiation of cone photoreceptors in the vertebrate retina. Rainbow trout undergo a natural process of cone cell degeneration during development and this change in photoreceptor distribution is regulated by thyroxine (T4; a thyroid hormone). In an effort to further understand the role of T4 in photoreceptor ontogeny and later developmental changes in photoreceptor subtype distribution, the influence of enhanced in ovo T4 content on the onset of opsin expression and cone development was examined. Juvenile trout reared from the initial in ovo-treated embryos were challenged with exogenous T4 at the parr stage of development to determine if altered embryonic exposure to yolk THs would affect later T4-induced short-wavelength-sensitive (SWS1) opsin transcript downregulation and ultraviolet-sensitive (UVS) cone loss. In ovo TH manipulation led to upregulation of both SWS1 and long-wavelength-sensitive (LWS) opsin transcripts in the pre-hatch rainbow trout retina and to changes in the relative expression of TRβ. After 7 days of exposure to T4, juveniles that were also treated with T4 in ovo had greatly reduced SWS1 expression levels and premature loss of UVS cones relative to T4-treated juveniles raised from untreated eggs. These results suggest that changes in egg TH levels can have significant consequences much later in development, particularly in the retina.

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Title: In ovo thyroxine exposure alters later UVS cone loss in juvenile rainbow trout
Creators: Jason C Raine - Department of Biology, Queen's University, Kingston, ON K7L 3N6, Canada
Allison B Coffin
Craig W Hawryshyn
Publication Details: Journal of experimental biology, Vol.214(Pt 13), pp.2248-2257
Academic Unit: Integrative Physiology and Neuroscience, Department of
Publisher: England
Identifiers: 99900547239101842
Language: English
Resource Type: Journal article