English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Thyroid hormone (TH) orchestrates amphibian metamorphosis. Thus, this developmental phase is often used to study TH-dependent responses in specific tissues. However, TH signaling appears early in development raising the question of the control of TH availability in specific cell types prior to metamorphosis. TH availability is under strict temporal and tissue-specific control by deiodinases. We examined the expression of the TH-inactivating enzyme, deiodinase type 3 (D3), during early retinal development. To this end we created a  Xenopus laevis  transgenic line expressing GFP from the Xenopus  dio3  promoter region (p dio3 ) and followed p dio3 –GFP expression in pre-metamorphic tadpoles. To validate retinal GFP expression in the transgenic line as a function of  dio3  promoter activity, we used  in situ  hybridization to compare endogenous  dio3  expression to reporter-driven GFP activity. Retinal expression of  dio3  increased during pre-metamorphosis through stages NF41, 45 and 48. Both sets of results show  dio3  to have cell-specific, dynamic expression in the pre-metamorphic retina. At stage NF48,  dio3  expression co-localised with markers for photoreceptors, rods, Opsin-S cones and bipolar neurons. In contrast, in post-metamorphic juveniles  dio3  expression was reduced and spatially confined to certain photoreceptors and amacrine cells. We compared  dio3  expression at stages NF41 and NF48 with TH-dependent transcriptional responses using another transgenic reporter line:  THbZIP -GFP and by analyzing the expression of T 3 -regulated genes in distinct TH availability contexts. At stage NF48, the majority of retinal cells expressing  dio3  were negative for T 3  signaling. Notably, most ganglion cells were virtually both  dio3- free and T 3 -responsive. The results show that  dio3  can reduce TH availability at the cellular scale. Further, a reduction in  dio3  expression can trigger fine-tuned T 3  action in cell-type specific maturation at the right time, as exemplified here in photoreceptor survival in the pre-metamorphic retina.

Expression of the inactivating deiodinase, Deiodinase 3, in the pre-metamorphic tadpole retina