Study of amino acid transporters in rainbow trout

Abstract:

The global expansion of aquaculture over the last three decades is now facing new ecological and economic challenges. It is becoming imperative to overcome them in order to develop this activity in a sustainable manner and thus feed a human population with exponential demographics. One of these challenges stems from the dependence of aquaculture on industrial fishing for the supply of fishmeal and fish oil needed to feed farmed fish. For many years, the scientific community has been working to identify alternatives to fishmeal. At present, the best considered alternative, i.e. the substitution of fishmeal by vegetable meal, still does not ensure optimal growth of fish, especially carnivorous species such as rainbow trout. In fact, despite a rebalancing of the amino acid profile of these new plant-based diets by adding free amino acids to cover the needs of the fish, the growth performance obtained remains below that usually observed with fishmeal-based diets. Previous data, as well as our own preliminary results, suggest that a lack of absorption of the supplemented free amino acids, associated with deregulation of the expression of amino acid transporters, is responsible for the poorer growth performances of fish fed with plant-based diets. In this context, through comprehensive approaches, from molecular and cellular technics (cell culture) to in vivo experimentations, the proposed thesis project aims to identify all the amino acid transporters in rainbow trout and to study their nutrient regulation modes.

Key words: Cell culture, Transporters, Signalling, Amino acid metabolism, autophagy, growth factor, fish, aquaculture

Labortory expertise: The NuMéA unit benefits from experimental facilities, unique in Europe, which gives us a perfect autonomy for carrying out nutrition and metabolism experiments on the complete biological life cycle of rainbow trout. In addition, the unit has all the equipment necessary for molecular (RT-qPCR, Western blot, UPLC-MS...) and cellular studies (primary and cell line cultures). Thus, by combining in vitro and in vivo approaches, the NuMéA laboratory's research is based on an integrative biology approach ranging from the study of the regulation of gene expression to the performance of the animal in its rearing system, made possible by a panel of complementary skills and adapted analytical devices.

Scientific framework

Previous results obtained in the lab (Morin et al., 2020) confirmed that amino acids are not only building blocks for protein synthesis but are also signalling molecules controlling anabolic and catabolic pathways in rainbow trout cell lines. Although it has already been shown that dietary amino acids play a major role in the metabolism of rainbow trout - and thus its growth – to date, none of the mechanisms by which amino acids are imported into the cells are known in rainbow trout.

Purpose(s)

In this context, we propose to study amino acid metabolism in rainbow trout, from specific amino acid transporter activities to signalling pathways governed by amino acids. Thus, by combining in vitro and in vivo experiments, we aim to identify amino acid transporters in trout and study their specificities as well as the outcomes of their different expression levels on trout metabolism and physiology.

Expected results

Altogether this study will considerably help to better understand amino acid metabolism in trout and will offer new strategies to develop appropriate diets for trout aquaculture.

Research collaborations

The successful candidate will work in a young and dynamic group in close collaborations with local, national and international talented scientists. He/she will also be given the opportunity to be involved in the teaching program of the University of Pau for a total of 32 hours per years.

Morin, G., Pinel, K., Dias, K., Seiliez, I., and Beaumatin, F. (2020). RTH-149 Cell Line, a Useful Tool to Decipher Molecular Mechanisms Related to Fish Nutrition. Cells 9, 1754.