Impacts of Embryonic Thermal Programming on the Expression of Genes Involved in Foie gras Production in Mule Ducks

Embryonic thermal programming has been shown to improve foie gras production in overfed mule ducks. However, the mechanisms at the origin of this programming have not yet been characterized. In this study, we investigated the effect of embryonic thermal manipulation (+1°C, 16 h/24 h from embryonic (E) day 13 to E27) on the hepatic expression of genes involved in lipid and carbohydrate metabolisms, stress, cell proliferation and thyroid hormone pathways at the end of thermal manipulation and before and after overfeeding (OF) in mule ducks. Gene expression analyses were performed by classic or high throughput real-time qPCR. First, we confirmed well-known results with strong impact of OF on the expression of genes involved in lipid and carbohydrates metabolisms. Then we observed an impact of OF on the hepatic expression of genes involved in the thyroid pathway, stress and cell proliferation. Only a small number of genes showed modulation of expression related to thermal programming at the time of OF, and only one was also impacted at the end of the thermal manipulation. For the first time, we explored the molecular mechanisms of embryonic thermal programming from the end of heat treatment to the programmed adult phenotype with optimized liver metabolism.

Slightly different metabolomic profiles are associated with high or low weights duck foie gras

Understanding the evolution of fatty liver metabolism of ducks is a recurrent issue for researchers and industry. Indeed, the increase in weight during the overfeeding period leads to an important change in the liver metabolism. However, liver weight is highly variable at the end of overfeeding within a batch of animals reared, force-fed and slaughtered in the same way. For this study, we performed a proton nuclear magnetic resonance ( 1 H-NMR) analysis on two classes of fatty liver samples, called low-weight liver (weight between 550 and 599 g) and high-weight liver (weight above 700 g). The aim of this study was to identify the differences in metabolism between two classes of liver weight (low and high). Firstly, the results showed that increased liver weight is associated with higher glucose uptake leading to greater lipid synthesis. Secondly, this increase is probably also due to a decline in the level of export of triglycerides and cholesterol from the liver by maintaining them at high hepatic concentration levels. Finally, the increase in liver weight could lead to a significant decrease in the efficiency of aerobic energy metabolism associated with a significant increase in the level of oxidative stress.

Application of Metabolomics to Identify Hepatic Biomarkers of Foie Gras Qualities in Duck

Foie gras is a traditional dish in France that contains 50 to 60% of lipids. The high-fat content of the liver improves the organoleptic qualities of foie gras and reduces its technological yield at cooking (TY). As the valorization of the liver as foie gras products is strongly influenced by the TY, classifying the foie gras in their potential technological quality before cooking them is the main challenge for producers. Therefore, the current study aimed to identify hepatic biomarkers of foie gras qualities like liver weight (LW) and TY. A group of 120 male mule ducks was reared and overfed for 6–12 days, and their livers were sampled and analyzed by proton nuclear magnetic resonance (1H-NMR). Eighteen biomarkers of foie gras qualities were identified, nine for LW and TY, five specific to LW, and four specific to TY. All biomarkers were strongly negatively correlated to the liver weights and positively correlated to the technological yield, except for the lactate and the threonine, and also for the creatine that was negatively correlated to foie gras technological quality. As a result, in heavy livers, the liver metabolism was oriented through a reduction of carbohydrate and amino acid metabolisms, and the plasma membrane could be damaged, which may explain the low technological yield of these livers. The detected biomarkers have been strongly discussed with the metabolism of the liver in nonalcoholic steatohepatitis.

A Novel Fluorescence Optical Imaging Scoring System for Hand Synovitis in Rheumatoid Arthritis – validity and agreement with ultrasound

Objectives To develop and validate a new semiquantitative Fluorescence Optical Imaging (FOI) scoring system – the FOI Enhancement-Generated rheumatoid arthritis (RA) Score (FOIE-GRAS) for synovitis assessment in the hand. Methods The development of FOIE-GRAS was based on consensus of 4 experts in musculoskeletal imaging. Forty-six RA patients, eligible for treatment intensification and with ≥1 clinically swollen joint in the hands and 11 healthy controls were included. FOI, ultrasound and clinical assessment of both hands were obtained at baseline and for RA patients after 3- and 6-months’ follow-up. Twenty RA patients had an FOI rescan after 4 hours. Synovitis was scored using FOIE-GRAS and the OMERACT ultrasound synovitis scoring system. All FOI images were scored by 2 readers. Inter-scan, inter-and intra-reader reliability were determined. Furthermore, FOIE-GRAS agreement with ultrasound and responsiveness was assessed. Results FOIE-GRAS synovitis was defined as early enhancement and scores based on the degree of coverage of the specific joint region after 3 seconds (0–3). Inter-scan, intra- and inter-reader intraclass correlations coefficients (ICC) were good-excellent for all baseline scores (0.76-0.98) and moderate-to-good for change (0.65-76). The FOIE-GRAS had moderate agreement with ultrasound (ICC 0.30-0.54) for total score, a good standardized response mean (>0.80), and moderate correlation with clinical joint assessment and DAS28-CRP. The median (IQR) reading time per FOI examination was 133 (109;161) seconds. Scores were significantly lower in controls 1(0;4) than RA patients 11(6;19). Conclusion The FOIE-GRAS offers a feasible and reliable assessment of synovitis in RA, with a moderate correlation with ultrasound and DAS28CRP, and good responsiveness.

Identification of Plasmatic Biomarkers of Foie Gras Qualities in Duck by Metabolomics

The foie gras is an emblematic product of French gastronomy composed of waterfowl fatty liver. The organoleptic qualities of this product depend on the liver characteristics such as liver weight (LW) and technological yield (TY) at cooking. One of the main issues for producers is to classify the foie gras with high or low technological quality before cooking them. Thus the study aims at identifying biomarkers of these characteristics with non-invasive biomarkers in duck. 1H-NMR (nuclear magnetic resonance of the proton) analyses were performed on plasma of male mule ducks at different time points during the overfeeding period to obtain a large range of liver characteristics so as to identify plasmatic biomarkers of foie gras. We used two methods, one based on bucket data from the 1H-NMR spectra and another one based on the fingerprints of several metabolites. PLS analyses and Linear models were performed to identify biomarkers. We identified 18 biomarkers of liver weight and 15 biomarkers of technological yield. As these two quality parameters were strongly correlated (−0.82), 13 biomarkers were common. The lactate was the most important biomarker, the other were mainly amino acids. Contrary to the amino acids, the lactate increased with the liver weight and decreased with the technological yield. We also identified 5 biomarkers specific to LW (3 carbohydrates: glucuronic acid, mannose, sorbitol and 2 amino acids: glutamic acid and methionine) that were negatively correlated to liver weight. It was of main interest to identify 2 biomarkers specific to the technological yield. Contrary to the isovaleric acid, the valine was negatively correlated to the technological yield.

Conditions d’élevage des palmipèdes à foie gras : des demandes sociétales à une démarche de progrès

La pratique du gavage des palmipèdes consiste à introduire un tube (embuc) dans l’œsophage des animaux pour y déposer de l’aliment en quantité croissante afin de produire du foie gras. Cette pratique est remise en question et fortement contestée par des associations de protection animale et une partie de la société. En l’absence d’une alternative efficace, elle reste toutefois la seule façon de produire du foie gras à grande échelle, produit auquel reste attachée une majorité de français. Cette synthèse replace la production de foie gras au sein des questions sociétales autour du bien-être des animaux et fait le point sur les données scientifiques sur l’impact du gavage au sens large (introduction de l’embuc, charge alimentaire, mode d’hébergement) sur différents indicateurs de l’état de l’animal. Il apparaît ainsi notamment que i) le gavage et l’hypertrophie hépatique ne sont probablement pas nociceptifs en conditions normales de gavage ; ii) les animaux sont sensibles à la capture et à la contention ; iii) la fonction hépatique et la structure histologique sont préservées et l’hypertrophie hépatique est réversible ; iv) le gavage induit des modifications comportementales : augmentation de la fréquence d’abreuvement et de halètement sans apparition d’hypoxie ; diminution de la fréquence du toilettage ; v) ces comportements varient par ailleurs en fonction des conditions climatiques et de la configuration des logements ; vi) le gavage peut générer des blessures spécifiques (blessure de l’œsophage) lorsqu’il est mal réalisé et les conditions d’hébergement des animaux tendent à aggraver les lésions préexistantes (lésions des pattes) ; vii) la mortalité augmente pendant la période de gavage. Cet article synthétise aussi les connaissances et ressources disponibles pour mettre au point une méthode d’évaluation de l’état de l’animal, qui soit multicritère, adaptée aux palmipèdes pendant la phase de gavage et utilisable en ferme. Une telle évaluation permettrait d’objectiver l’état de confort ou d’inconfort des animaux et d’accompagner la filière de production de foie gras dans une démarche de progrès.

Ontogeny of hepatic metabolism in mule ducks highlights different gene expression profiles between carbohydrate and lipid metabolic pathways

Background The production of foie gras involves different metabolic pathways in the liver of overfed ducks such as lipid synthesis and carbohydrates catabolism, but the establishment of these pathways has not yet been described with precision during embryogenesis. The early environment can have short- and long-term impacts on the physiology of many animal species and can be used to influence physiological responses that is called programming. This study proposes to describe the basal hepatic metabolism at the level of mRNA in mule duck embryos in order to reveal potential interesting programming windows in the context of foie gras production. To this end, a kinetic study was designed to determine the level of expression of selected genes involved in steatosis-related liver functions throughout embryogenesis. The livers of 20 mule duck embryos were collected every 4 days from the 12th day of embryogenesis (E12) until 4 days after hatching (D4), and gene expression analysis was performed. The expression levels of 50 mRNAs were quantified for these 7 sampling points and classified into 4 major cellular pathways. Results Interestingly, most mRNAs involved in lipid metabolism are overexpressed after hatching (FASN, SCD1, ACOX1), whereas genes implicated in carbohydrate metabolism (HK1, GAPDH, GLUT1) and development (HGF, IGF, FGFR2) are predominantly overexpressed from E12 to E20. Finally, regarding cellular stress, gene expression appears quite stable throughout development, contrasting with strong expression after hatching (CYP2E1, HSBP1, HSP90AA1). Conclusion For the first time we described the kinetics of hepatic ontogenesis at mRNA level in mule ducks and highlighted different expression patterns depending on the cellular pathway. These results could be particularly useful in the design of embryonic programming for the production of foie gras.