Temperature induced variation in gene expression of thyroid hormone receptors and deiodinases of European eel (Anguilla anguilla) larvae

S. N. Politis (1) , Arianna Servili (2, 3) , David Mazurais (2, 3) , Jose-Luis Zambonino-Infante (2, 3) , J. J. Miest (4) , J. Tomkiewicz (1) , I. A. E. Butts (1)

1 DTU Aqua, National Institute of Aquatic Resources
2 LEMAR - Laboratoire des Sciences de l'Environnement Marin (LEMAR)
3 IFREMER - Institut Français de Recherche pour l'Exploitation de la Mer
4 GEOMAR - Helmholtz Centre for Ocean Research [Kiel]

Thyroid hormones (THs) are key regulators of growth, development, and metabolism in vertebrates and influence early life development of fish. TH is produced in the thyroid gland (or thyroid follicles) mainly as T4 (thyroxine), which is metabolized to T3 (3,5,3'-triiodothyronine) and T2 (3,5-diiodothyronine) by deiodinase (DIO) enzymes in peripheral tissues. The action of these hormones is mostly exerted by binding to a specific nuclear thyroid hormone receptor (THR). In this study, we i) cloned and characterized thr sequences, ii) investigated the expression pattern of the different subtypes of thrs and dios, and iii) studied how temperature affects the expression of those genes in artificially produced early life history stages of European eel (Anguilla anguilla), reared in different thermal regimes (16, 18, 20 and 22 degrees C) from hatch until first-feeding. We identified 2 subtypes of thr (thr alpha and thr beta) with 2 isoforms each (thr alpha A, thr alpha B, thr beta A, thr beta beta) and 3 subtypes of deiodinases (dio1, dio2, dio3). All thr genes identified showed high similarity to the closely related Japanese eel (Anguilla japonica). We found that all genes investigated in this study were affected by larval age (in real time or at specific developmental stages), temperature, and/or their interaction. More specifically, the warmer the temperature the earlier the expression response of a specific target gene. In real time, the expression profiles appeared very similar and only shifted with temperature. In developmental time, gene expression of all genes differed across selected developmental stages, such as at hatch, during teeth formation or at first-feeding. Thus, we demonstrate that thrs and dios show sensitivity to temperature and are involved in and during early life development of European eel.

Mots clés: ACL; Aquaculture; Fish; atlantic cod; Early life history; embryonic-development; gadus-morhua; iodothyronine outer ring; japanese eel; life-cycle; oncorhynchus-mykiss; rainbow-trout; sargasso sea; water temperature

Domaines: Biodiversité et Ecologie

S. N. Politis, Arianna Servili, David Mazurais, Jose-Luis Zambonino-Infante, J. J. Miest, et al.. Temperature induced variation in gene expression of thyroid hormone receptors and deiodinases of European eel (Anguilla anguilla) larvae. General and Comparative Endocrinology, 2018, 259, pp.54-65. ⟨10.1016/j.ygcen.2017.11.003⟩. ⟨hal-02640321⟩