Thyroid in intestinal development during atlantic salmon smoltification

Atlantic salmon (Salmo salar L.) has a complex lifecycle. It starts its life in FW, grows, and after several changes at behavioral, morphological, and physiological levels, a process called smoltification, the fish migrate downstream to the sea. During this process of seawater (SW) acquisition, the osmoregulatory organs encompass critical changes, especially due to the excess of ions. The intestine is one of the osmoregulatory organs, and the tissue will receive the nutrients and ions, process them, and handle the osmotic pressure gain in SW. This organ needs to be equipped to accommodate these changes. Thyroid hormones (THs) play an essential role in developing and differentiating the intestine in tadpoles and mammals. They are important in the preparation for new environments, such as the passage from the aquatic to the terrestrial environment in the tadpoles. TH are involved in salmon metabolic and morphological changes. The present PhD thesis gives a novel insight into intestinal morphology, intestinal SW acquisition, and involvement of TH in intestinal development during the freshwater (FW) and the development of competence for the SW phase. Here we used a winter signal (Photoperiod manipulation) and functional feeds (salt and amino acid enriched feeds) to putatively manipulate the process of smoltification in freshwater and focused our effort on the characterization of the intestinal response. The two intestinal regions, anterior and posterior intestine, have different responses as a result of light and salt-enriched feed treatments. The anterior intestine is more responsive to those treatments and to TH just before SW transfer. In this thesis, we show that even though triiodothyronine (T3), the active TH hormone, has an effect on intestinal development, and in its preparation for developing SW tolerance. However, T3 alone it is not a sufficient factor for a complete intestinal adaptation to the marine environment. Our data, together with other studies, indicates that size and the metabolic status of the fish are likely the determinant factors for a successful SW adaptation in Atlantic salmon.

Author dc:creator

• Fernandes Duarte, Vilma Vanessa

Advisors dc:contributor.advisor

• Campinho, Marco António
• Fuentes Díaz, Juan

Statement dc:rights

• Attribution-NonCommercial-NoDerivatives 4.0 Internacional

Licence dc:rights.uri

• http://creativecommons.org/licenses/by-nc-nd/4.0/

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/10498/34034

OAI identifier oai:identifier

oai:rodin.uca.es:10498/34034