A Peer-to-Peer Normative System to Achieve Social Order

International audienceSocial order in distributed descentralised systems is claimed to be obtained by using social norms and social control. This paper presents a normative P2P architecture to obtain social order in multi-agent systems. We propose the use of two types of norms that coexist: rules and conventions. Rules describe the global normative constraints on autonomous agents, whilst conventions are local norms. Social control is obtained by providing a non-intrusive control infrastructure that helps the agents build reputation values based on their respect of norms. Some experiments are presented that show how communities are dynamically formed and how bad agents are socially excluded

The effect of a diet with fructan-rich chicory roots on intestinal helminths and microbiota with special focus on Bifidobacteria and Campylobacter in piglets around weaning

The restrictions on the use of antibiotic and anthelmintic treatments in organic pig farming necessitate alternative non-medical control strategies. Therefore, the antibiotic and parasite-reducing effect of a fructan-rich (prebiotic) diet of dried chicory was investigated in free-ranging piglets. Approximately half of 67 piglets from 9 litters were experimentally infected with Ascaris suum and Trichuris suis in the suckling period (1 to 7 weeks of age) and 58 of the piglets were challenged daily with E. coli O138:F8 for 9 days after weaning to induce weaning diarrhoea. The litters were fed either chicory (30% DM) or a control diet. The effect of chicory on intestinal helminths, intestinal microbiota, especially Bifidobacteria and Campylobacter spp., and E. coli post-weaning diarrhoea was assessed. The weight gain of the piglets was not impaired significantly by chicory. The intestinal A. suum worm burden was reduced by 64% (P=0.034) in the chicory-fed piglets, whereas these same piglets had 63% more T. suis worms (P=0.016). Feeding with chicory elicited no changes among the main bacterial groups in ileum according to terminal restriction fragment length polymorphism (T-RFLP) analysis. However, the terminal-restriction fragment (T-RF) 208 bp, which may belong to Lachnospiraceae, was stimulated by the chicory feed (P=0.03), and T-RF 370 bp that matches Enterobacter belonging to the Enterobacteria was reduced (P=0.004). Additionally, chicory increased the level of Bifidobacteria (P=0.001) and the faecal Campylobacter excretion level was transitorily reduced in chicory-fed piglets at 7 weeks of age (P=0.029). Unfortunately, it was not possible to assess the effect of chicory on post-weaning diarrhoea as it did not develop. In conclusion, feeding piglets chicory around the time of weaning caused complex changes of the microbiota and parasite communities within the intestinal tract, and feeding piglets chicory may therefore serve as an animal-friendly strategy to control pathogens

An ecological perspective on microbes and immune defences in avian eggs

Lichaamseigen micro-organismen beïnvloeden veel eigenschappen van de gastheer, maar hun invloed op fysiologische flexibiliteit wordt vaak over het hoofd gezien. Door eieren te gebruiken als een eenvoudig model voor de vogel, heb ik de link tussen microbiële gemeenschappen en antimicrobiële afweersystemen kunnen onderzoeken. Ik focus mij op de familie van de leeuwerik (Alaudidae), die voorkomt in grote delen van Eurazië en Afrika, maar overal overeenkomstige eigenschappen heeft. Met een zelf-ontwikkelde techniek om het eierschaal-bioom te karakteriseren, heb ik aangetoond dat dit micro-bioom en de antimicrobiële eiwitten in het ei dynamisch zijn. Zowel de bacteriedichtheid en -diversiteit, als de aanwezigheid van bepaalde antimicrobiële eiwitten nemen toe tijdens de broedperiode. Het micro-bioom van de eischaal lijkt bovendien een paar dagen na het leggen al meer op die van de veren van de moeder, dan die van de cloaca of het nest. Dit benadrukt het belang van horizontale transmissie voor micro-organismen. Omdat microbiële gemeenschappen worden beperkt door omgevingsfactoren, heb ik vervolgens micro-biomen van eischalen tussen klimatologisch verschillende omgevingen in Kenia onderzocht. Eischalen uit een koelere omgeving hadden een grotere bacteriedichtheid, terwijl het warmste gebied de meeste diversiteit vertoonde. Er was echter geen verschil in antimicrobiële eiwitten. Ik vond geen verschil tussen micro-biomen van Keniaanse en Nederlandse eischalen. Ondanks de lage variatie in afweereigenschappen, vond ik wel correlaties tussen bacteriesoorten en antimicrobiële eiwitten. Het onderzoeken van de functionele diversiteit van micro-biomen van eischalen zal inzicht geven in de rol die zij spelen in het reduceren van kostbare maternale investeringen in het afweersysteem van eieren

RÔLE DE LA LEUCINE CONTRE LE DÉVELOPPEMENT DE LA SARCOPÉNIE

A progressive loss of muscle mass has been well described in both humans and rodents during ageing. This loss of proteins results from an imbalance between protein synthesis and degradation rates. Although some authors have shown a decrease of myofibrillar protein synthesis rates in human volunteers, this imbalance is not clearly apparent when basal rates of protein turnover are measured. A decrease in muscle protein synthesis stimulation has nevertheless been detected in ageing rats during the postprandial period, suggesting that the ‘meal signal’ is altered during ageing. Many results now suggest that aged muscle is less sensitive to the stimulatory effect of amino acids at physiological concentrations, but is still able to respond if the increase in aminoacidaemia is sufficiently large. Indeed, amino acids play an important role in regulating muscle protein turnover both in vitro and in vivo. Of amino acids, leucine seems to play the key role in regulating the metabolic function. It inhibits proteolysis and stimulates muscle protein synthesis independently of insulin. Leucine has been shown to act as a mediator, by modulating specifically the activities of intracellular kinases linked to the translation of proteins such as phosphatidylinositol 3_ kinase and mammalian target of rapamycin – 70 kDa ribosomal protein S6 (p70S6K) kinases. We recently demonstrated in vitro that protein synthesis in ageing rat muscles becomes resistant to the stimulatory effect of leucine in its physiological concentration range. Protein synthesis was however stimulated normally when the leucine concentration was increased well above its postprandial level. We also studied the effect of meal leucine supplementation on in vivo protein synthesis in adult and ageing rats. Leucine supplementation had no additional effect on muscle protein synthesis in adults but totally restored its stimulation in ageing rats. Whether chronic oral leucine supplementation would be beneficial for maintaining muscle protein mass in elderly humans remains to be studied.Une diminution de la masse musculaire au cours du vieillissement est aujourd'hui bien décrite chez l'Homme et l'animal. Cette perte de protéines résulte d'un déséquilibre entre synthèse et dégradation des protéines musculaires. Bien que certains auteurs aient pu montrer une diminution de la synthèse des protéines myofibrillaires chez l'Homme, ce déséquilibre est difficilement apparent dans la plupart des études menées à l'état post-absorptif. Cependant, une altération de la stimulation de la synthèse des protéines a été mise en évidence chez le rat âgé au cours de la phase post-prandiale suggérant que « l'effet repas » normalement observé était altéré au cours du vieillissement. Plusieurs travaux ont montré que le muscle âgé était moins sensible à l'effet anabolique des acides aminés aux concentrations physiologiques mais qu'il était toujours en mesure de répondre si d'importantes hyper-aminoacidémies étaient générées. En effet les acides aminés jouent un rôle majeur dans la régulation du métabolisme protéique, que ce soit in vivo ou in vitro. Parmi eux, la leucine semble être celui qui présente le plus fort effet. La leucine seule est capable d'inhiber la protéolyse et de stimuler la synthèse protéique indépendamment de l'insuline. Cet acide aminé, en plus d'être un substrat, est également un véritable médiateur cellulaire en modulant spécifiquement les activités de plusieurs kinases impliquées dans la régulation de l'initiation de la synthèse des protéines i.e phosphatidylinositol 3_ kinase and mammalian target of rapamycin-70 kDa ribosomal protein 56 (p70S6K) kinases. Nous avons montré récemment in vitro que la synthèse protéique musculaire devenait résistante à l'effet stimulateur de la leucine chez le rat âgé dans l'intervalle de ces concentrations physiologique. Cependant, si les concentrations de leucine étaient largement supérieures aux valeurs post-prandiales, la protéosynthèse était stimulée normalement. Nous avons donc étudié l'effet d'une supplémentation en leucine du régime sur la protéosynthèse du rat adulte et âgé in vivo. Cette supplémentation n'a pas eu d'effet additionnel chez l'adulte mais a permis de restaurer totalement la régulation post-prandiale du métabolisme protéique musculaire chez l'âgé. L'effet bénéfique d'une telle supplémentation en nutrition entérale chronique sur le maintien de la masse musculaire au cours du vieillissement reste cependant à étudier

Shifts in bacterial communities of eggshells and antimicrobial activities in eggs during incubation in a ground-nesting passerine

Microbial invasion of egg contents is a cause of embryonic death. To counter infection risks, the embryo is protected physically by the eggshell and chemically by antimicrobial proteins. If microbial pressure drives embryo mortality, then females may have evolved, through natural selection, to adapt their immune investment into eggs. Although frequently hypothesized, this match between immune allocation and microorganisms has not been explored yet. To examine if correlations between microbes on eggs and immunity in eggs exist, we collected eggs from red-capped larks (Calandrella cinerea) and simultaneously examined their bacterial communities and antimicrobial components--pH, lysozyme and ovotransferrin--during natural incubation. Using molecular techniques, we find that bacterial communities are highly dynamic: bacterial abundance increases from the onset to late incubation, Shannon's α-diversity index increases during early incubation stages, and β-diversity analysis shows that communities from 1 day-old clutches are phylogenetically more similar to each other than the older ones. Regarding the antimicrobials, we notice a decrease of pH and lysozyme concentration, while ovotransferrin concentration increases during incubation. Interestingly, we show that two eggs of the same clutch share equivalent immune protection, independent of clutch age. Lastly, our results provide limited evidence of significant correlation between antimicrobial compounds and bacterial communities. Our study examined simultaneously, for the first time in a wild bird, the dynamics of bacterial communities present on eggshells and of albumen-associated antimicrobial components during incubation and investigated their relationship. However, the link between microorganisms and immunity of eggs remains to be elucidated further. Identifying invading microbes and their roles in embryo mortality, as well as understanding the role of the eggshell microbiome, might be key to better understand avian strategies of immune maternal investment

Acute Oral Poisoning Due to Chloracetanilide Herbicides

Chloracetanilide herbicides (alachlor, butachlor, metachlor) are used widely. Although there are much data about chronic low dose exposure to chloracetanilide in humans and animals, there are few data about acute chloracetanilide poisoning in humans. This study investigated the clinical feature of patients following acute oral exposure to chloracetanilide. We retrospectively reviewed the data on the patients who were admitted to two university hospitals from January 2006 to December 2010. Thirty-five patients were enrolled. Among them, 28, 5, and 2 cases of acute alachlor, metachlor, butachlor poisoning were included. The mean age was 49.8 ± 15.4 yr. The poison severity score (PSS) was 17 (48.6%), 10 (28.6%), 5 (14.3%), 2 (5.7%), and 1 (2.9%) patients with a PSS of 0, 1, 2, 3, and 4, respectively. The age was higher for the symptomatic patients (1-4 PSS) than that for the asymptomatic patients (0 PSS) (43.6 ± 15.2 vs 55.7 ± 13.5). The arterial blood HCO3 ¯ was lower in the symptomatic patients (1-4 PSS) than that in the asymptomatic patients (0 PSS). Three patients were a comatous. One patient died 24 hr after the exposure. In conclusion, although chloracetanilide poisoning is usually of low toxicity, elder patients with central nervous system symptoms should be closely monitored and cared after oral exposure

Microbiome assembly of avian eggshells and their potential as transgenerational carriers of maternal microbiota

The microbiome is essential for development, health and homeostasis throughout an animal's life. Yet, the origins and transmission processes governing animal microbiomes remain elusive for non-human vertebrates, oviparous vertebrates in particular. Eggs may function as transgenerational carriers of the maternal microbiome, warranting characterisation of egg microbiome assembly. Here, we investigated maternal and environmental contributions to avian eggshell microbiota in wild passerine birds: woodlark Lullula arborea and skylark Alauda arvensis. Using 16S rRNA gene sequencing, we demonstrated in both lark species, at the population and within-nest levels, that bacterial communities of freshly laid eggs were distinct from the female cloacal microbiome. Instead, soil-borne bacteria appeared to thrive on freshly laid eggs, and eggshell microbiota composition strongly resembled maternal skin, body feather and nest material communities, sources in direct contact with laid eggs. Finally, phylogenetic structure analysis and microbial source tracking underscored species sorting from directly contacting sources rather than in vivo-transferred symbionts. The female-egg-nest system allowed an integrative assessment of avian egg microbiome assembly, revealing mixed modes of symbiont acquisition not previously documented for vertebrate eggs. Our findings illuminated egg microbiome origins, which suggested a limited potential of eggshells for transgenerational transmission, encouraging further investigation of eggshell microbiome functions in vertebrates