Caroline Molette

Proteomic profile evolution during steatosis development in ducks

We investigated a protein profile evolution during steatosis in ducks using 2-dimensional electrophoresis gels to better understand the mechanisms underlying liver steatosis at the level of hepatic proteins in waterfowl. Two-dimensional electrophoresis gels were performed in the liver at different stages of steatosis in the duck. Mule ducks were slaughtered after 0, 14, or 23 meals of overfeeding, according to commercial conditions. Thirty-one proteic spots were differentially expressed between 3 or 2 durations of overfeeding: 3 spots were differentially expressed between the 3 times and 28 spots were differentially expressed between 2 times. The identified proteins (14) could be regrouped into 5 categories: enzymes, translation factors, proteins involved in cell structure, proteins with antioxidant properties, and proteins that can link calcium. This study opens new research areas in the understanding of steatosis in waterfowl, such as cell structure and oxidative stress.

Using 2-DE for the differentiation of local chicken breeds

The aim of this study was to apply a proteomic approach for the characterisation of local chicken breeds. The experiment involved a total of 29 males of three local Italian chicken breeds: Pépoi, Padovana and Ermellinata di Rovigo. Sarcoplasmic protein fractions of breast muscle were analysed by 2‐DE. Image analysis followed by statistical analysis enabled to differentiate groups of individuals based on the similarities of protein expression. Individuals were distinguished into clusters and groups, corresponding to the breed of origin. Distances among individuals, calculated using data on spot volumes, were used to draw a neighbour‐joining tree, showing clear individual and breed grouping. The most relevant spots regarding breed differentiation were detected; 11 were identified by MS revealing preliminary evidences on the mechanisms of the breed differentiation process. The results evidenced the ability of proteomic analyses for the characterisation of chicken breeds.

Functional genomics of the muscle response to restraint and transport in chickens

In the present study, we used global approaches (proteomics, transcriptomics, and metabolomics) to assess the molecular basis of the muscle response to stress in chickens. A restraint test, combined with transport for 2 h (RT test) was chosen as the potentially stressful situation. Chickens (6 wk old) were either nontreated (control chickens) or submitted to the RT test (treated chickens). The RT test induced a 6-fold increase in corticosterone concentrations, suggesting hypothalamic-pituitary-adrenal axis activation. The RT test decreased the relative abundance of several hexose phosphates [glucose-1-P (G1P), glucose-6-P (G6P), fructose-6-P (F6P), and mannose-6-P (M6P)] in thigh muscle. In addition, 55 transcripts, among which 39 corresponded to unique annotated genes, were significantly up- (12 genes) or downregulated (27 genes) by treatment. Similarly, 45 proteic spots, among which 29 corresponded to unique annotated proteins, were overexpressed (11 proteins), underexpressed (14 proteins), or only expressed in treated chickens. Integrative analysis of differentially expressed genes and proteins showed that most transcripts and proteins belong to 2 networks whose genes were mainly related with cytoskeleton structure or carbohydrate metabolism. Whereas the decrease in energetic metabolites suggested an activation of glycogenolysis and glycolysis in response to the RT test, the reduced expression of genes and proteins involved in these pathways suggested the opposite. We hypothesized that the prolonged RT test resulted in a repression of glycogenolysis and glycolysis in thigh muscle of chickens. The down-expression of genes and proteins involved in the formation of fiber stress after the RT test suggests a reinforcement of myofibrils in response to stress.

Duration of transport and holding in lairage at constant postprandial delay to slaughter—Effects on fatty liver and breast muscle quality in mule ducks

The present study was designed to evaluate the effect of preslaughter transport (30 vs. 150 min) and holding of mule ducks in lairage in their transport crates (15 vs. 120 min) on the quality of the meat and fatty liver. A total of 120 birds were allocated in a 2 × 2 factorial design with a constant postprandial delay to slaughter (8 h), to avoid the confounding between the effects of the experimental treatments and those of fasting duration. Under such conditions, extending the transport or holding duration did not induce a loss in preslaughter live weight or liver weight. Similarly, breast muscle glycogen stores were not affected by the treatments, nor was the kinetics of postmortem pH decline affected. The mechanical resistance of raw meat obtained by the compression test significantly increased with holding duration. The gross chemical composition of the livers did not differ significantly among the preslaughter treatments. Residual blood in the liver, as indicated by heme pigment concentration, was enhanced with a longer transport, but this effect was more pronounced after the longest holding duration, as shown by a significant interaction. This, however, did not significantly affect the incidence of appearance defects or the commercial grading of the livers. The percentage of fat loss during the cooking of canned livers was significantly reduced when the transport duration was increased. This effect could not be explained on the basis of the current knowledge for determining the technological quality of fatty liver. The identification of biological markers of liver quality is currently underway in our laboratory. Further investigations studying the differential expression of these biological markers according to preslaughter conditions would provide a better understanding of the effect of transport duration on liver processing yield.

Current advances in proteomic analysis of (fatty) liver.

In this review, an overview on proteomic studies conducted in livers of farm animals is conducted with a special focus on liver steatosis in waterfowl. Several studies had interest in understanding liver metabolism in dairy cows under various conditions (e.g. fasting) or the evolution of liver proteome during embryonic phases or growing periods in chicken. Those studies provide interesting results leading to a better understanding of the liver metabolism. Liver steatosis development in waterfowl represents a special case and a focus on proteomic studies conducted in these birds will be done. Indeed, recent studies aimed at resolving protein evolution during overfeeding in duck. Proteomic analysis combining two complementary approaches (2-dimensional electrophoresis gels and shot gun strategy) in order to better understand the mechanisms underlying the variability of cooking yield of fatty liver will be presented.

Direct and correlated responses to selection in two lines of rabbits selected for feed efficiency under ad libitum and restricted feeding: I. Production traits and gut microbiota characteristics

To get insights into selection criteria for feed efficiency, 2 rabbit lines have been created: the ConsoResidual line was selected for residual feed intake (RFI) with ad libitum feeding and the ADGrestrict line was selected for ADG under restricted feeding (-20% of voluntary intake). The first objective of this study was to evaluate, after 9 generations of selection, the direct and correlated responses to selection on production traits in the 2 lines for traits recorded during growth. Second, applying the 2 feeding conditions used for selection to both selected lines plus the control unselected line (generation 0, G0) in a 2 × 3 factorial trial, the line performances were compared and the gut microbiota of the lines was characterized. The correlated responses in feed conversion ratio (FCR) were remarkably equivalent in both selected lines (-2.74 genetic σ) but correlated responses in other traits were notably different. In the ConsoResidual line, selection for decreased RFI resulted in a small negative correlated response in BW at 63 d old (BW63) and in a null response in ADG. In the ADGrestrict line, on the contrary, the correlated response in BW63 was substantial (+1.59 σ). The 2 selected lines had a FCR reduced by 0.2 point compared with the G0 line, and the same difference was found in both feeding regimens ( < 0.001). Indeed, selection on ADG would lead to heavier animals with no significant reduction of feed costs, whereas selection on RFI leads to lower feed costs and no increase of animal BW under ad libitum feeding. Altogether, our results do not suggest any genotype × environment interaction in the response to feeding regimens. The intestinal microbial communities from efficient rabbits differed from their unselected counterparts in terms of fermentation end products and microbial phylotypes, suggesting a central role of these microbes in the better feed efficiency of the rabbits.

Are one early muscle pH and one early temperature measurement sufficient to detect PSE breast meat in turkeys

1. Within a large flock of turkey toms (2000 BUT9 conventionally reared and slaughtered), early muscle pH measurements were randomly done to distinguish two groups of birds presenting low (fast glycolysing, GR) or normal (normal glycolysing, GN) values. 2. Subsequently, ultimate pH values and meat quality parameters were also recorded. Meat quality parameters from GR or GN samples differ more or less indicating more or less severe PSE conditions. Proteins extracted from the samples at 20 min post mortem were similar while they differed greatly at 24 h post mortem. Moreover, among the GR birds, a subgroup of animals (called AB) presented SDS-PAGE profiles largely different from other GR or GN birds. 3. All the subsequent analysis developed on meat quality parameters as well as for protein extractabilities also differed between AB and other animals indicating that they must be considered differently in term of PSE syndrome development. 4. Western blots against Myosin Heavy Chain and actin at 24 h post mortem indicate that myofibrillar protein alterations are different in AB and GR or GN samples. 5. At 20 min post mortem, glycogen content was lowest in AB samples while the glycolytic potential was similar in all samples at the time of death. Measurements of PFK enzyme specific activity did not indicate a different regulation of post mortem glycolysis in AB samples. 6. Our results suggest that a unique pH measurement at 20 min post is insufficient to detect animals more prone to developing a severe PSE syndrome in turkeys. In consequence, it is suggested that a more precise evaluation of the kinetics of pH and temperature decrease has to be conducted to understand the aetiology of meat quality parameter alterations in poultry.

The influence of choice feeding and cereal type (corn or triticale) during the finishing period on performance of mule ducks

The aim of this trial was to study the influence of choice feeding and cereal type (corn or triticale) during the finishing period on performance of ducks. In total, 624 one-day-old male mule ducks (Cairina moschata × Anas platyrhynchos) were divided into 3 groups differing in the diet they received between 56 and 84 d of age: a commercial complete pelleted diet (control group; AMEn 12.1 MJ/kg, CP 15%), or corn whole seeds (AMEn 14.4 MJ/kg, CP 7.3%) and protein-rich pellets (AMEn 9.9 MJ/kg, CP 22.7%) in 2 separated feeders [choice feeding with corn (CFC) group]; or triticale whole seeds (AMEn 13.0 MJ/kg, CP 10.5%) and protein-rich pellets (AMEn 11.2 MJ/kg, CP 19.5%) in 2 separated feeders [choice feeding with triticale (CFT) group]. From 85 to 96 d, 96 birds/group were overfed with corn. Feed intake (complete pellets or cereal and protein-rich pellets) per pen was measured at 60, 62, 65, 69, 78, and 84 d of age. Body weight and body traits were measured at 56 to 84 d of age. Over the entire period, from 56 to 84 d, the feed intake of the CFC group was 7% lower than the control group, and 5% lower than that in the CFT group (P = 0.002). Whatever the diet tested, at 56 and 84 d of age, the BW (4,099 and 4,779 g, P = 0.42 and P = 0.35, respectively) and the carcass traits (P > 0.05) of ducks were similar in the 3 groups. During and after overfeeding, the performances of the ducks were also similar (P > 0.05). The present results suggest that CFC during the finishing period is a solution to reduce the cost of diet destined to ducks. Indeed, using locally grown grains could reduce the economic and environmental impacts of duck feeding, reducing the transportation and crushing processes.

Proteome response of fish under multiple stress exposure: Effects of pesticide mixtures and temperature increase.

Aquatic systems can be subjected to multiple stressors, including pollutant cocktails and elevated temperature. Evaluating the combined effects of these stressors on organisms is a great challenge in environmental sciences. To the best of our knowledge, this is the first study to assess the molecular stress response of an aquatic fish species subjected to individual and combined pesticide mixtures and increased temperatures. For that, goldfish (Carassius auratus) were acclimated to two different temperatures (22 and 32°C) for 15 days. They were then exposed for 96h to a cocktail of herbicides and fungicides (S-metolachlor, isoproturon, linuron, atrazine-desethyl, aclonifen, pendimethalin and tebuconazole) at two environmentally relevant concentrations (total concentrations of 8.4μgL-1 and 42μgL-1) at these two temperatures (22 and 32°C). The molecular response in liver was assessed by 2D-proteomics. Identified proteins were integrated using pathway enrichment analysis software to determine the biological functions involved in the individual or combined stress responses and to predict the potential deleterious outcomes. The pesticide mixtures elicited pathways involved in cellular stress response, carbohydrate, protein and lipid metabolisms, methionine cycle, cellular functions, cell structure and death control, with concentration- and temperature-dependent profiles of response. We found that combined temperature increase and pesticide exposure affected the cellular stress response: the effects of oxidative stress were more marked and there was a deregulation of the cell cycle via apoptosis inhibition. Moreover a decrease in the formation of glucose by liver and in ketogenic activity was observed in this multi-stress condition. The decrease in both pathways could reflect a shift from a metabolic compensation strategy to a conservation state. Taken together, our results showed (1) that environmental cocktails of herbicides and fungicides induced important changes in pathways involved in metabolism, cell structure and cell cycle, with possible deleterious outcomes at higher biological scales and (2) that increasing temperature could affect the response of fish to pesticide exposure.

Protein Matrix Involved in the Lipid Retention of Foie Gras during Cooking: A Multimodal Hyperspectral Imaging Study

Denaturation of the protein matrix during heat treatment of duck foie gras was studied in relationship to the amount of fat loss during cooking. A low fat loss group was compared with a high fat loss group by histochemistry, FT-IR, and synchrotron UV microspectroscopy combination to characterize their protein matrix at different scales. After cooking, the high fat loss group showed higher densification of its matrix, higher ultraviolet tyrosine autofluorescence, and an infrared shift of the amide I band. These results revealed a higher level of protein denaturation and aggregation during cooking in high fat loss than in low fat loss foie gras. In addition, the fluorescence and infrared responses of the raw tissue revealed differences according to the level of fat losses after cooking. These findings highlight the importance of the supramolecular state of the protein matrix in determining the fat loss of foie gras.