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Short and long term programming consequences of a high carbohydrate nutrition of trout broodstock on progeny
Reference
1560341372
Deadline for applications
06/28/2019
Date of publication
06/12/2019

Details

Details on the type of contract
PhD contract
Duration of contract
36 months
Beginning
10/01/2019

Remuneration
Growth salary : 1878 €

Assignment

Name of unit of assignment
UMR1419 NUMEA Nutrition, Métabolisme, Aquaculture
Address of unit of assignment
INRA Aquapôle de Saint-Pée-sur-Nivelle 173 Route de Saint-Jean-de-Luz RD 918 64310 SAINT-PEE-SUR-NIVELLE
Website of unit of assignment
https://www6.bordeaux-aquitaine.inra.fr/st_pee_eng/UR-NuMeA
Region of assignment
Nouvelle-Aquitaine

Description

Working environment

Description of the lab :

Researches in the INRA lab NuMeA/UPPA (Nutrition, Metabolism, Aquaculture) are conducted in a context of limited marine resources and a strong aquaculture development worldwide. They aim to understand the regulation of the metabolic pathways by nutrients in fish, using an integrative approach (from genes to the animal). The finalized goal is to provide recommendations for innovative strategies in aquaculture feeds in order to optimize growth and feed efficiency in respect of sustainability.

One objective of NuMeA is to develop “New feeding strategies” to remove the obstacles that limit the replacement of fish meal and fish oil in aquafeeds. To contribute to these issues, the scientific objectives are to acquire new knowledge on the regulation of ingestion and carbohydrate utilization, and to identify metabolic pathways strongly affected by the new diets. The post-doctorate belongs to this theme of research.

  

Missions and scientific activities :

Context :

Since the 1980’s, aquaculture, and particularly salmonid aquaculture in Europe, has developed and already provide a large portion (73.8 million tons) of fish supply for human food. As a reliable supply of fish production for human increasing needs, this industry is expected to grow at an annual rate close to 6.3% in the next years. However, reducing the reliance of aquaculture on wild fish resources while ensuring the sustainability of salmonid aquaculture, the main fresh water production in Europe, fishmeal (FM) and fish oil (FO), the traditional ingredients of aquafeeds (Naylor et al., 2009), must be replaced by renewable, eco-friendly and less costly alternative terrestrial plant products, and particularly digestible carbohydrates. This is particularly true for salmonid broodstock breeding as these animals consume a high quantity of expensive diet and reject important quantity of nitrogen. Indeed

the main source of energy in salmon comes from proteins provided by FM. Increasing the proportion of digestible carbohydrates in aquafeed may be one solution to reduce the cost of broodstock feeding because they are easy and economical to produce. Moreover such a replacement will help to limit broodstock environmental impact by providing another energy source, saving protein for growth and thus limiting nitrogen waste.

However, salmonids and more particularly rainbow trout (the main fresh water fish produce in Europe) are carnivorous species, and thus usually consider as glucose-intolerant (GI) species and poor user of dietary carbohydrates (Polakof et al., 2012) displaying a decrease in growth and a persistent postprandial hyperglycaemia when fish meal (FM) is substituted at more than 20% by digestible carbohydrates in the diet. In particular, the non-inhibition of the last step of the hepatic gluconeogenesis is suspected to be involved in this GI phenotype in trout (Marandel et al., 2015; Marandel et al., 2016; Marandel et al., 2017). However, these findings were mainly deduced from experiments conducted on immature trout juvenile. Studies published in the 90’s strongly suggested that a metabolic switch between liver and gonads (i.e. a modification in glycolysis and glycogen storage in liver in favor of gonads), more particularly related to glucose metabolism, occurred during gametogenesis in both males and females (Soengas, 1993a; Soengas, 1993b). In this regard, we recently demonstrated that trout broodstock (both male and female) are able to be good users of dietary digestible carbohydrates and able to regulate and modulate their intermediary metabolism in this purpose. The first mission of the PhD student will be thus to investigate the consequences of a high dietary carbohydrate diet on broodstock metabolism and reproductive performances.

   

Nevertheless it is now well accepted that early environmental events, of a nutritional or non-nutritional nature, occurring during the perinatal life at critical developmental windows (including gametogenesis) may result in permanent changes in postnatal growth potential, health and metabolic status (Lillycrop et al., 2005; Burdge et al., 2011; Liu et al., 2017). The notion of early programming has clearly been established in fish and especially in trout (Geurden et al., 2014; Liu et al., 2017). Thus our hypothesize is that feeding broodstock with a high content of digestible carbohydrates should impact, through gametes modifications, the phenotype and the intermediary metabolism of offspring in the short and long term. The PhD student will thus then investigate this hypothesis at the transcriptional level.

In mammals, programming has been shown to be triggered mostly by epigenetics mechanisms (Lillycrop et al., 2007). We also recently demonstrated that digestible dietary carbohydrates could act as epigenetic modulators in trout liver and more particularly by inducing DNA methylation changes (Marandel et al., 2016) which were remarkably correlated to transcriptional changes into gluconeogenic genes. Thus, based on transcriptional results, epigenetic mechanisms would be investigated.

  

The PhD student will publish the results of the project and disseminate them in international meetings.

Training and skills required

Diploma : Master in biology, molecular biology or agronomy

Skills : molecular biology skills will be an advantage and theoretical/practical skills in epigenetics and hightroughput techniques will be appreciated but are not required.                                                                                     

Additionnal appreciated skills   : Knowledge in fish biology and nutrition will be an advantage but is not mandatory.

Qualities : Great communication skills, good English knowledge and autonomy are required. He/she will also participate in lab maintenance and samplings.

 

Selected candidates will be interviewed on the second week of July (8th, 9th or 10th).

This thesis includes a teaching load of 96 hours to be taught over the 3 years of the thesis for the PhD student .

Send a motivation letter and a CV including the name of two referees to Lucie MARANDEL.

Contact

Name
Lucie MARANDEL
Telephone
+33 5 59 51 59 81
Email
lucie.marandel@inra.fr