Prawn Shell Chitosan Has Anti-Obesogenic Properties, Influencing Both Nutrient Digestibility and Microbial Populations in a Pig Model

This study was supported financially (Grant-Aid Agreement No. MFFRI/07/01) under the Sea Change Strategy with the support of the Marine Institute and the Department of Agriculture, Food and the Marine, funded under the National Development Plan 2007–2013.peer-reviewedThe potential of natural products to prevent obesity have been investigated, with evidence to suggest that chitosan has anti-obesity effects. The current experiment investigated the anti-obesity potential of prawn shell derived chitosan on a range of variables relevant to obesity in a pig model. The two dietary treatment groups included in this 63 day study were: T1) basal diet and T2) basal diet plus 1000 ppm chitosan (n = 20 gilts per group (70 ± 0.90 kg). The parameter categories which were assessed included: performance, nutrient digestibility, serum leptin concentrations, nutrient transporter and digestive enzyme gene expression and gut microbial populations. Pigs offered chitosan had reduced feed intake and final body weight (P< 0.001), lower ileal digestibility of dry matter (DM), gross energy (GE) (P< 0.05) and reduced coefficient of apparent total tract digestibility (CATTD) of gross energy and nitrogen (P<0.05) when compared to the basal group. Fatty acid binding protein 2 (FABP2) gene expression was down-regulated in pigs offered chitosan (P = 0.05) relative to the basal diet. Serum leptin concentrations increased (P< 0.05) in animals offered the chitosan diet compared to pigs offered the basal diet. Fatness traits, back-fat depth (mm), fat content (kg), were significantly reduced while lean meat (%) was increased (P<0.05) in chitosan supplemented pigs. Pigs offered chitosan had decreased numbers of Firmicutes in the colon (P <0.05), and Lactobacillus spp. in both the caecum (P <0.05) and colon (P <0.001). Bifidobacteria populations were increased in the caecum of animals offered the chitosan diet (P <0.05). In conclusion, these findings suggest that prawn shell chitosan has potent anti-obesity/body weight control effects which are mediated through multiple biological systems in vivo.This study was supported financially (Grant-Aid Agreement No. MFFRI/07/01) under the Sea Change Strategy with the support of the Marine Institute and the Department of Agriculture, Food and the Marine, funded under the National Development Plan 2007–2013

Transcriptome analysis of porcine M. semimembranosus divergent in intramuscular fat as a consequence of dietary protein restriction

peer-reviewedBackground: Intramuscular fat (IMF) content is positively correlated with aspects of pork palatability, including flavour, juiciness and overall acceptability. The ratio of energy to protein in the finishing diet of growing pigs can impact on IMF content with consequences for pork quality. The objective of this study was to compare gene expression profiles of Musculus semimembranosus (SM) of animals divergent for IMF as a consequence of protein dietary restriction in an isocaloric diet. The animal model was derived through the imposition of low or high protein diets during the finisher stage in Duroc gilts. RNA was extracted from post mortem SM tissue, processed and hybridised to Affymetrix porcine GeneChip® arrays. Results: IMF content of SM muscle was increased on the low protein diet (3.60 ± 0.38% versus 1.92 ± 0.35%). Backfat depth was also greater in animals on the low protein diet, and average daily gain and feed conversion ratio were lower, but muscle depth, protein content and moisture content were not affected. A total of 542 annotated genes were differentially expressed (DE) between animals on low and high protein diets, with 351 down-regulated and 191 up-regulated on the low protein diet. Transcript differences were validated for a subset of DE genes by qPCR. Alterations in functions related to cell cycle, muscle growth, extracellular matrix organisation, collagen development, lipogenesis and lipolysis, were observed. Expression of adipokines including LEP, TNFα and HIF1α were increased and the hypoxic stress response was induced. Many of the identified transcriptomic responses have also been observed in genetic and fetal programming models of differential IMF accumulation, indicating they may be robust biological indicators of IMF content. Conclusion: An extensive perturbation of overall energy metabolism in muscle occurs in response to protein restriction. A low protein diet can modulate IMF content of the SM by altering gene pathways involved in lipid biosynthesis and degradation; however this nutritional challenge negatively impacts protein synthesis pathways, with potential consequences for growth.Department of Agriculture, Food and the Marine, Ireland - Food Institutional Research Measur

Neural computations underlying inverse reinforcement learning in the human brain

In inverse reinforcement learning an observer infers the reward distribution available for actions in the environment solely through observing the actions implemented by another agent. To address whether this computational process is implemented in the human brain, participants underwent fMRI while learning about slot machines yielding hidden preferred and non-preferred food outcomes with varying probabilities, through observing the repeated slot choices of agents with similar and dissimilar food preferences. Using formal model comparison, we found that participants implemented inverse RL as opposed to a simple imitation strategy, in which the actions of the other agent are copied instead of inferring the underlying reward structure of the decision problem. Our computational fMRI analysis revealed that anterior dorsomedial prefrontal cortex encoded inferences about action-values within the value space of the agent as opposed to that of the observer, demonstrating that inverse RL is an abstract cognitive process divorceable from the values and concerns of the observer him/herself

Long-tailed Duck, Clangula hyemalis, Eider, Somateria spp., and Scoter, Melanitta spp., Distributions in Central Alaska Beaufort Sea Lagoons, 1999-2002

During July and August 1999–2002, distributions of Long-tailed Ducks (Clangula hyemalis), eiders (Somateria spp.) and scoters (Melanitta spp.) were documented in three barrier island-lagoon systems in the central Alaska Beaufort Sea. Concentration areas for each species were determined during 16 aerial surveys. Kernel density procedures were used to delineate 75% and 50% “activity” or concentration areas for all three species. Long-tailed Ducks were 13 times more numerous than eiders and 38 times more numerous than scoters. The Long-tailed Duck 75% activity area encompassed all three lagoon systems and was three times as large as the eider activity area and one-third larger than the scoter activity area. Eider activity areas were located only in the eastern lagoon, and scoter activity areas were located only in the western lagoon. Density contours showed patterns of repeated habitat use for sea ducks over the four years of sampling and improve our understanding of sea duck habitat use within Beaufort Sea barrier island-lagoon habitats

Behavioural evidence for parallel outcome-sensitive and outcome-insensitive Pavlovian learning systems in humans

There is a dichotomy in instrumental conditioning between goal-directed actions and habits that are distinguishable on the basis of their relative sensitivity to changes in outcome value. It is less clear whether a similar distinction applies in Pavlovian conditioning, where responses have been found to be predominantly outcome-sensitive. To test for both devaluation-insensitive and devaluation-sensitive Pavlovian conditioning in humans, we conducted four experiments combining Pavlovian conditioning and outcome-devaluation procedures while measuring multiple conditioned responses. Our results suggest that Pavlovian conditioning involves two distinct types of learning: one that learns the current value of the outcome, which is sensitive to devaluation, and one that learns about the spatial localization of the outcome, which is insensitive to devaluation. Our findings have implications for the mechanistic understanding of Pavlovian conditioning and provide a more nuanced understanding of Pavlovian mechanisms that might contribute to a number of psychiatric disorders

Motor Preparatory Activity in Posterior Parietal Cortex is Modulated by Subjective Absolute Value

For optimal response selection, the consequences associated with behavioral success or failure must be appraised. To determine how monetary consequences influence the neural representations of motor preparation, human brain activity was scanned with fMRI while subjects performed a complex spatial visuomotor task. At the beginning of each trial, reward context cues indicated the potential gain and loss imposed for correct or incorrect trial completion. FMRI-activity in canonical reward structures reflected the expected value related to the context. In contrast, motor preparatory activity in posterior parietal and premotor cortex peaked in high “absolute value” (high gain or loss) conditions: being highest for large gains in subjects who believed they performed well while being highest for large losses in those who believed they performed poorly. These results suggest that the neural activity preceding goal-directed actions incorporates the absolute value of that action, predicated upon subjective, rather than objective, estimates of one's performance

A study of protein and amino nutrition of growing pigs.

End of Project ReportProtein nutrition of the pig is concerned primarily with supplying the amino acid requirements for fast, efficient growth and development of a lean carcass. In addition, surplus protein contributes to a high level of nitrogen excretion in manure which is a problem in complying with the Nitrates Directive. Metabolism of the excess protein / nitrogen in the pig involves creation of urea and this process depresses the efficiency of energy utilisation. As the pig grows, its requirement for individual amino acids falls but the optimum ratio changes. Providing a diet with the correct levels and balance of the principal amino acids is expected to improve performance. Improvements in genetics and changes in management such as slaughter weight require that the amino acid requirements be reassessed periodically. The objective of this study was to examine response of pigs to variation in dietary lysine in several weight ranges with the concentrations of the other principal amino acids held constant. Entire males had superior FCR to females in all trials except 15 to 30kg, but differences in dietary lysine requirements did not occur until the finishing stage. At heavier weights, response of male and female pigs began to diverge at lysine concentrations greater than 10.7 g/kg (ADG) and 9.7 g/kg (FCR). There appeared to be a need to increase the threonine to lysine ratio in the diet from 0.60 to 0.70 when lysine concentration was reduced from 12.0 to 9.5 g/kg as weight of the pig increased. Providing the same mean lysine content (11.1 g/kg) to pigs from 38 to 97 kg in a series of five diets declining in lysine concentration compared with a single diet did not affect performance, or reduce N excretion. However, lowering the overall mean lysine concentration from 11g/kg to 10.0 g/kg reduced overall N excretion by 13 %, without a negative effect on pig performance. Pigs which were offered a low lysine diet in the early stage of growth exhibited a compensatory response during realimentation on a high lysine diet but it was not sufficient to equal the overall performance of pigs previously offered a lysine-adequate diet. Nitrogen excretion was reduced by 23 % while the low lysine diet was fed in the initial period but there was no residual effect on N excretion during realimentation.Teagasc Walsh Fellowship ProgrammeNational Development Programme Funds (NDP

Common Eider (Somateria mollissima v-nigrum) Nest Cover and Depredation on Central Alaskan Beaufort Sea Barrier Islands

Female common eiders (Somateria mollissima v-nigrum) generally select nest sites in areas with driftwood cover. Previous studies of common eiders have shown a positive relationship between nest success and driftwood cover. Our observations led us to hypothesize that cover does not enhance nest success when mammalian predators are present. To evaluate nest cover selection in common eiders, we examined five years of nesting data to determine the interactions between the probability of nest activity and the amount of driftwood cover in the presence of avian versus mammalian predators. Most common eider nests were surrounded by low (40%) or moderate (38%) driftwood cover. Nest failure rates were high (32%– 95%), and arctic foxes (Alopex lagopus), alone or with polar bears (Ursus maritimus), appeared to be more destructive than glaucous gulls (Larus hyperboreus) to eider nests. Logistic regression was used to model common eider nest activity associated with driftwood cover and predators. When glaucous gulls were the only predators, more driftwood cover consistently increased the probability of nest activity. But when foxes were present, nest activity consistently decreased with increasing cover. Our models support our observations that nest cover was beneficial to eiders when glaucous gulls alone were predators. Driftwood cover may be most important for the thermal and structural protection it offers, rather than for the camouflage it provides. The energetic benefit provided by driftwood windbreaks coupled with the common eider’s behavioral response of decreased nest attendance, or increased exposure to avian depredation of nests as energy reserves are depleted during incubation, provides an explanatory mechanism for our model results.L’eider à duvet femelle (Somateria mollissima v-nigrum) choisit en général son site de nidification dans des zones ayant un couvert de bois flotté. Des études précédentes sur les eiders à duvet ont révélé qu’il existe une relation positive entre le succès de la couvée et le couvert de bois flotté. Nos observations nous ont amenés à émettre l’hypothèse que le couvert n’augmente pas le succès de la couvée en présence de prédateurs mammifères. Afin d’évaluer le choix de couvert du nid chez l’eider à duvet, nous avons examiné des données de nidification obtenues sur cinq années, en vue de dégager les interactions entre la probabilité d’activité au nid et la quantité de couvert de bois flotté en présence de prédateurs aviens par opposition aux prédateurs mammifères. La plupart des nids de l’eider à duvet étaient entourés par un faible couvert de bois flotté (40 %) ou un couvert modéré (38 %). Les taux d’insuccès étaient élevés (32 à 95 %) et le renard arctique (Alopex lagopus), seul ou avec l’ours polaire (Ursus maritimus), semblait plus destructeur pour les nids de l’eider que le goéland bourgmestre (Larus hyperboreus). On a utilisé la régression logistique pour simuler l’activité au nid de l’eider à duvet associée au couvert de bois flotté et aux prédateurs. Quand le goéland bourgmestre était le seul prédateur, une plus grande quantité de bois flotté augmentait toujours la probabilité d’activité au nid. En revanche, en présence du renard, l’activité au nid diminuait toujours avec une augmentation du couvert. Nos modèles viennent appuyer nos observations à l’effet que le couvert du nid représentait un avantage pour l’eider quand le goéland bourgmestre était le seul prédateur. Le couvert de bois flotté pourrait bien être d’une importance capitale en raison de la protection thermique et structurale qu’il offre, plutôt que pour ses capacités de camouflage. L’avantage énergétique qu’offrent les brise-vent de bois flotté joint à la réaction comportementale de l’eider à duvet – qui se manifeste par une plus grande présence au nid, ou une plus grande exposition à une déprédation avienne du nid à mesure que s’épuisent les réserves d’énergie durant l’incubation –, ces deux éléments donc fournissent un mécanisme pouvant expliquer les résultats de notre modèle