The bacteriohopanepolyol inventory of novel aerobic methane oxidising bacteria reveals new biomarker signatures of aerobic methanotrophy in marine systems

Aerobic methane oxidation (AMO) is one of the primary biologic pathways regulating the amount of methane (CH4) released into the environment. AMO acts as a sink of CH4, converting it into carbon dioxide before it reaches the atmosphere. It is of interest for (paleo)climate and carbon cycling studies to identify lipid biomarkers that can be used to trace AMO events, especially at times when the role of methane in the carbon cycle was more pronounced than today. AMO bacteria are known to synthesise bacteriohopanepolyol (BHP) lipids. Preliminary evidence pointed towards 35-aminobacteriohopane-30,31,32,33,34-pentol (aminopentol) being a characteristic biomarker for Type I methanotrophs. Here, the BHP compositions were examined for species of the recently described novel Type I methanotroph bacterial genera Methylomarinum and Methylomarinovum, as well as for a novel species of a Type I Methylomicrobium. Aminopentol was the most abundant BHP only in Methylomarinovum caldicuralii, while Methylomicrobium did not produce aminopentol at all. In addition to the expected regular aminotriol and aminotetrol BHPs, novel structures tentatively identified as methylcarbamate lipids related to C-35 amino-BHPs (MCBHPs) were found to be synthesised in significant amounts by some AMO cultures. Subsequently, sediments and authigenic carbonates from methane-influenced marine environments were analysed. Most samples also did not contain significant amounts of aminopentol, indicating that aminopentol is not a useful biomarker for marine aerobic methanotophic bacteria. However, the BHP composition of the marine samples do point toward the novel MC-BHPs components being potential new biomarkers for AMO

FXR agonists and FGF15 reduce fecal bile acid excretion in a mouse model of bile acid malabsorption

Bile acid malabsorption, which in patients leads to excessive fecal bile acid excretion and diarrhea, is characterized by a vicious cycle in which the feedback regulation of bile acid synthesis is interrupted, resulting in additional bile acid production. Feedback regulation of bile acid synthesis is under the control of an endocrine pathway wherein activation of the nuclear bile acid receptor, farnesoid X receptor (FXR), induces enteric expression of the hormone, fibroblast growth factor 15 (FGF15). In liver, FGF15 acts together with FXR-mediated expression of small heterodimer partner to repress bile acid synthesis. Here, we show that the FXR-FGF15 pathway is disrupted in mice lacking apical ileal bile acid transporter, a model of bile acid malabsorption. Treatment of Asbt-/- mice with either a synthetic FXR agonist or FGF15 downregulates hepatic cholesterol 7alpha-hydroxylase mRNA levels, decreases bile acid pool size, and reduces fecal bile acid excretion. These findings suggest that FXR agonists or FGF15 could be used therapeutically to interrupt the cycle of excessive bile acid production in patients with bile acid malabsorption

Influence of solvent granularity on the effective interaction between charged colloidal suspensions

We study the effect of solvent granularity on the effective force between two charged colloidal particles by computer simulations of the primitive model of strongly asymmetric electrolytes with an explicitly added hard sphere solvent. Apart from molecular oscillating forces for nearly touching colloids which arise from solvent and counterion layering, the counterions are attracted towards the colloidal surfaces by solvent depletion providing a simple statistical description of hydration. This, in turn, has an important influence on the effective forces for larger distances which are considerably reduced as compared to the prediction based on the primitive model. When these forces are repulsive, the long-distance behaviour can be described by an effective Yukawa pair potential with a solvent-renormalized charge. As a function of colloidal volume fraction and added salt concentration, this solvent-renormalized charge behaves qualitatively similar to that obtained via the Poisson-Boltzmann cell model but there are quantitative differences. For divalent counterions and nano-sized colloids, on the other hand, the hydration may lead to overscreened colloids with mutual attraction while the primitive model yields repulsive forces. All these new effects can be accounted for through a solvent-averaged primitive model (SPM) which is obtained from the full model by integrating out the solvent degrees of freedom. The SPM was used to access larger colloidal particles without simulating the solvent explicitly.Comment: 14 pages, 16 craphic

General scientific guidance for stakeholders on health claim applications

The European Food Safety Authority (EFSA) asked the Panel on Dietetic Products Nutrition and Allergies (NDA) to update the General guidance for stakeholders on the evaluation of Article 13.1, 13.5 and 14 health claims published in March 2011. Since then, the NDA Panel has completed the evaluation of Article 13.1 claims except for claims put on hold by the European Commission, and has evaluated additional health claim applications submitted pursuant to Articles 13.5, 14 and also 19. In addition, comments received from stakeholders indicate that general issues that are common to all health claims need to be further clarified and addressed. This guidance document aims to explain the general scientific principles applied by the NDA Panel for the evaluation of all health claims and outlines a series of steps for the compilation of applications. The general guidance document represents the views of the NDA Panel based on the experience gained to date with the evaluation of health claims, and it may be further updated, as appropriate, when additional issues are addressed

Choline and contribution to normal liver function of the foetus and exclusively breastfed infants: evaluation of a health claim pursuant to Article 14 of Regulation (EC) No 1924/2006

Following an application from Procter & Gamble BV pursuant to Article 14 of Regulation (EC) No 1924/2006 via the Competent Authority of Belgium, the Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on the scientific substantiation of a health claim related to choline and contribution to normal liver function of the foetus and exclusively breastfed infant. The scope of the application was proposed to fall under a health claim referring to children's development and health. The Panel considers that choline is sufficiently characterised. The claimed effect proposed by the applicant is contribution ‘to normal foetal and infant development, especially liver’. The proposed target population is ‘unborn fetuses and breastfed infants’. Choline is involved in the structure of cell membranes, cell signalling, metabolism and transport of lipids and cholesterol and neurotransmitter synthesis. Although choline can be synthesised de novo by the human body, depletion-repletion studies in humans show that low choline intake leads to liver dysfunction and muscle damage, which are reverted by the administration of dietary choline. For these functions, de novo synthesis of choline by the human body is insufficient and choline must be obtained from dietary sources. No human studies have addressed the effect of low maternal dietary choline intake on liver function in the fetus or exclusively breastfed infants. However, the Panel considers that the biological role of choline in normal liver function and dietary choline being essential for the function applies to all ages, including fetus and infants. The Panel concludes that a cause and effect relationship has been established between the intake of choline by pregnant and lactating women and contribution to normal liver function of the fetus and exclusively breastfed infants

Appethyl® and reduction of body weight: evaluation of a health claim pursuant to Article 13(5) of Regulation (EC) No 1924/2006

Following an application from Greenleaf Medical AB, submitted for authorisation of a health claim pursuant to Article 13(5) of Regulation (EC) No 1924/2006 via the Competent Authority of Sweden, the EFSA Panel on Nutrition, Novel Foods and Food allergens (NDA) was asked to deliver an opinion on the scientific substantiation of a health claim related to Appethyl® and reduction of body weight. Appethyl® is an aqueous extract from spinach leaves standardised by the manufacturing process and its lipase/colipase inhibition capacity in vitro. The Panel considers that the food is sufficiently characterised. A reduction in body weight is a beneficial physiological effect for overweight/obese individuals. The applicant identified a total of three human intervention studies that investigated the effects of Appethyl® on body weight as being pertinent to the claim. In weighing the evidence, the Panel took into account that Appethyl® (5 g/day for 12 weeks) had no effect on body weight as compared to placebo under minimal dietary counselling and moderate physical activity, and that no beneficial physiological effects are to be expected for the target population of overweight/obese individuals from the weight loss that could be attributed to the intervention with Appethyl® under predefined energy restriction and moderate physical activity. The Panel also considered that the effect of Appethyl® (5 g/day for 24 weeks) on body weight maintenance after initial weight loss shown in one study has not been replicated in different settings, which questions the external validity of the results, and that no evidence was provided for a plausible mechanism by which daily consumption of Appethyl® could exert a sustained effect on body weight in humans. The Panel concludes that a cause-and-effect relationship has not been established between the consumption of Appethyl® and a reduction of body weight under the conditions of use proposed by the applicant

Isomaltulose and normal energy-yielding metabolism: evaluation of a health claim pursuant to Article 13(5) of Regulation (EC) No 1924/2006

Following an application from BENEO GmbH submitted for authorisation of a health claim pursuant to Article 13(5) of Regulation (EC) No 1924/2006 via the Competent Authority of Germany, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on the scientific substantiation of a health claim related to isomaltulose and normal energy-yielding metabolism. The scope of the application was proposed to fall under a health claim based on newly developed scientific evidence. The food proposed by the applicant as the subject of the health claim is isomaltulose. The Panel considers that isomaltulose is sufficiently characterised. The claimed effect proposed by the applicant is ‘normal energy-yielding metabolism’. The Panel considers that contribution to normal energy-yielding metabolism is a beneficial physiological effect. A number of human studies applying indirect calorimetry measurements or stable isotope methodologies have shown the postprandial metabolic utilisation of isomaltulose as energy source. However, all energy-containing macronutrients (i.e. carbohydrates, proteins, and lipids) supply the body with energy and this property is not specific to isomaltulose. The Panel concludes that a cause and effect relationship has been established between the intake of isomaltulose and contribution to energy-yielding metabolism. The following wording reflects the scientific evidence: ‘isomaltulose contributes to normal energy-yielding metabolism’. Since the contribution to energy-yielding metabolism is not specific to isomaltulose but applies to all energy containing macronutrients (i.e. carbohydrates, proteins, and lipids) that supply the body with metabolisable energy and any amount would contribute to the claimed effect, the Panel cannot set conditions of use for this claim. The applicant proposes that isomaltulose should replace other sugars in foods and/or beverages. The target population is the general population