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Project

Mechanisms of ammonia transport in marine fish with a different nitrogen metabolism.

Ammonia toxicity is a frequent problem in aquatic environments (aquaculture, eutrophication, …) which adversely affects fish performance and welfare. Fish also produce endogenous ammonia in their nitrogen metabolism, and it is their most important nitrogen waste product. Mechanistic strategies in fish gills to cope with ammonia toxicity and transport have fascinated biologists for many decades. The recent discovery of the ammonia transport function of Rhesus (Rh) glycoprotein has added a new major mechanism associated with ammonia handling at piscine gills. It was established that mammalian Rh glycoproteins, linked to antibody production in humans, are members of a protein family that mediates ammonia transport in broad group of organisms, suggesting a long evolutionary history. Also, the Rh family might have undergone some evolutionary changes among piscine phylogeny likely in association with the functional significance of ammonia handling. Among freshwater teleosts, Rh proteins are emerging as vital ammonia conduits, as was also evident from our studies in salmonids and cyprinids. Despite these recent advancements, very limited mechanistic information is available in marine teleosts and in more primitive marine cartilaginous fish such as sharks, rays and chimaeras, who show very different strategies for ionoregulation. Moreover, there is no consensus about the possible linkage of ammonia excretion with ion fluxes (in freshwater or marine fish) and the role the skin in ammonia excretion. Therefore, there is an urgent need to explore the evolution of mechanisms allied with ammonia handling in these different marine fish which possess very diverse ion-regulatory strategies. This project aims at characterizing and localizing Rh protein among the above-mentioned piscine groups, and at unravelling their involvement in ammonia transport. Additionally, it wants to establish possible links between ammonia and ion fluxes as well as the role of the skin in ammonia transport.
Date:1 Oct 2015 →  30 Sep 2019
Keywords:RHESUS GLYCOPROTEINS, AMMONIA, MARINE FISHES, FISH GILLS
Disciplines:Animal biology, General biology, Fisheries sciences, Veterinary medicine