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Post Doc: Short and long term programming consequences of a high carbohydrate nutrition of trout broodstock on progeny

Employeur : INRA Aquitaine

Job Location

France : Bordeaux

Publish date

13/09/18

Doctorat en:

Molecular biology

Job Description:

Deadline for application: 10/31/2018
Date of publication: 09/15/2018
Details: Details on the type of contract : Post-doctoral contract
Duration of contract: 36 months
Beginning: 01/01/2019
Gross salary: 2338€ to 2867€ (depending on experience)
Assignment
Name of unit of assignment: UMR1419, Nutrition, metabolism and aquaculture
Address of unit of assignment: Aquapole INRA, RD918, 64310 SAINT-PEE-SUR-NIVELLE
Website of unit of assignment: https://www6.bordeaux-aquitaine.inra.fr/st_pee/UMR-NuMeA
Region of assignment: New Aquitaine
Description
Working environment Research unit :
Researches in the INRA Unit NuMeA (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.
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 noninhibition 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 i this purpose.
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 post-doctorate will thus 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.

References
Burdge, G.C., Hoile, S.P., Uller, T., Thomas, N.A., Gluckman, P.D., Hanson, M.A. and Lillycrop, K.A., 2011. Progressive, transgenerational changes in offspring phenotype and epigenotype following nutritional transition. PLoS One 6, e28282.
Geurden, I., Mennigen, J., Plagnes-Juan, E., Veron, V., Cerezo, T., Mazurais, D., Zambonino-Infante, J., Gatesoupe, J., Skiba-Cassy, S. and Panserat, S., 2014. High or low dietary carbohydrate:protein ratios during first-feeding affect glucose metabolism and intestinal microbiota in juvenile rainbow trout. J Exp Biol 217, 3396-406.
Lillycrop, K.A., Phillips, E.S., Jackson, A.A., Hanson, M.A. and Burdge, G.C., 2005. Dietary protein restriction of pregnant rats induces and folic acid supplementation prevents epigenetic modification of hepatic gene expression in the offspring. J Nutr 135, 1382-6.
Lillycrop, K.A., Slater-Jefferies, J.L., Hanson, M.A., Godfrey, K.M., Jackson, A.A. and Burdge, G.C., 2007. Induction of altered epigenetic regulation of the hepatic glucocorticoid receptor in the offspring of rats fed a protein-restricted diet during pregnancy suggests that reduced DNA methyltransferase-1 expression is involved in impaired DNA methylation and changes in histone modifications. Br J Nutr 97, 1064-73.
Liu, J., Dias, K., Plagnes-Juan, E., Veron, V., Panserat, S. and Marandel, L., 2017. Long-term programming effect of early hypoxia and high carbohydrate diet at first-feeding on glucose metabolism in rainbow trout juveniles. J Exp Biol.
Marandel, L., Lepais, O., Arbenoits, E., Véron, V., Dias, K., Zion, M. and Panserat, S., 2016. Remodelling of the hepatic epigenetic landscape of glucose-intolerant rainbow trout (Oncorhynchus mykiss) by nutritional status and dietary carbohydrates. Scientific Reports 6, 32187.
Marandel, L., Panserat, S., Plagnes-Juan, E., Arbenoits, E., Soengas, J.L. and Bobe, J., 2017. Evolutionary history of glucose-6-phosphatase encoding genes in vertebrate lineages: towards a better understanding of the functions of multiple duplicates. BMC Genomics 18, 342.
Marandel, L., Seiliez, I., Veron, V., Skiba-Cassy, S. and Panserat, S., 2015. New insights into the nutritional regulation of gluconeogenesis in carnivorous rainbow trout (Oncorhynchus mykiss): a gene duplication trail. Physiol Genomics 47, 253-63.
Naylor, R.L., Hardy, R.W., Bureau, D.P., Chiu, A., Elliott, M., Farrell, A.P., Forster, I., Gatlin, D.M., Goldburg, R.J., Hua, K. and Nichols, P.D., 2009. Feeding aquaculture in an era of finite resources. Proc Natl Acad Sci U S A 106, 15103-10.
Polakof, S., Panserat, S., Soengas, J.L. and Moon, T.W., 2012. Glucose metabolism in fish: a review. J Comp Physiol B 182, 1015-45.
Soengas, J.L., B Sanmartin, P Barciela, M Aldegunde, G Rozas, 1993a. Changes in carbohydrate metabolism related to the onset of ovarian recrudescence in dmesticated rainbow trout (Oncorhynchus mykiss). Comparative Biochemistry and Physiology Part A: Physiology 105, 293-301.
Soengas, J.L., B. Sanmartín, P. Barciela, M. Aldegunde, G. Rozas, 1993b. Changes in carbohydrate metabolism in domesticated rainbow trout (Oncorhynchus mykiss) related to spermatogenesis. Comparative Biochemistry and Physiology Part B: Comparative Biochemistry 105, 665-671.

Profil / Qualifications Requises

Training and skills required
PhD in molecular biology, experience in microarray analysis is required and
theoretical/practical skills in epigenetics will be appreciated. Knowledge in fish biology and nutrition will be an advantage but is not mandatory. He/she will publish the results of the project and disseminate them in international meetings. Great communication skills, fluency in English and autonomy are required. He/she will also participate in lab maintenance and will be asked to participate in samplings.

Apply

Send a motivation letter and a CV including the name of two referees to Lucie MARANDEL (phone: +33 5 59 51 59 81, email : [email protected]).

[email protected]

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