Consequence of omitting or adding a meal in man on body composition, food intake, and metabolism

Objective: To investigate in man the consequence on body composition and related biological and metabolic parameters of omitting or adding a meal. Research Methods and Procedures: Twenty‐four young normal‐weight male subjects were recruited, 12 usual four‐meal and 12 usual three‐meal eaters, differing only in the consumption of an afternoon meal. They omitted or added a fourth meal during a 28‐day habituation period and were asked to report their intake on three 3‐day occasions. Before and after this habituation period, subjects participated in a session with a time‐blinded procedure, and blood was collected continuously from lunch to the spontaneously requested dinner. Body composition, respiratory quotient, and biochemical parameters were measured in the late evening preceding each session. Results: Omitting a meal was followed by increases in fat mass (360 ± 115 grams, p < 0.05), late evening leptin concentration (20.7 ± 11.0%, p < 0.05), and respiratory quotient (3.7 ± 1.4%, p < 0.05). Increase in the percentage of dietary fat during the habituation period (+4.1 ± 2.0%, p < 0.05) was correlated with fat mass (r = 0.66, p < 0.05). Adding a meal had no effect, but, in both groups, the change in energy content at this fourth eating occasion was correlated with the change in adiposity. Discussion: Our results suggest that adiposity may increase when young lean male subjects switch from a four‐ to a three‐meal pattern by removing their usual afternoon meal. This effect could be partly mediated by a change in the macronutrient composition of the diet.     

Intranasal vaccine from whole Leishmania donovani antigens provides protection and induces specific immune response against visceral leishmaniasis

Visceral leishmaniasis is a protozoan disease associated with high fatality rate in developing countries. Although the drug pipeline is constantly improving, available treatments are costly and live-threatening side effects are not uncommon. Moreover, an approved vaccine against human leishmaniasis does not exist yet. Using whole antigens from Leishmania donovani promastigotes (LdAg), we investigated the protective potential of a novel adjuvant-free vaccine strategy. Immunization of mice with LdAg via the intradermal or the intranasal route prior to infection decreases the parasitic burden in primary affected internal organs, including the liver, spleen, and bone marrow. Interestingly, the intranasal route is more efficient than the intradermal route, leading to better parasite clearance and remarkable induction of adaptive immune cells, notably the helper and cytotoxic T cells. In vitro restimulation experiments with Leishmania antigens led to significant IFN-γ secretion by splenocytes; therefore, exemplifying specificity of the adaptive immune response. To improve mucosal delivery and the immunogenic aspects of our vaccine strategy, we used polysaccharide-based nanoparticles (NP) that carry the antigens. The NP-LdAg formulation is remarkably taken up by dendritic cells and induces their maturation in vitro, as revealed by the increased expression of CD80, CD86 and MHC II. Intranasal immunization with NP-LdAg does not improve the parasite clearance in our experimental timeline; however, it does increase the percentage of effector and memory T helper cells in the spleen, suggesting a potential induction of long-term memory. Altogether, this study provides a simple and cost-effective vaccine strategy against visceral leishmaniasis based on LdAg administration via the intranasal route, which could be applicable to other parasitic diseases.     

The Evolution of Calcification in Reef-Building Corals

Corals build the structural foundation of coral reefs, one of the most diverse and productive ecosystems on our planet. Although the process of coral calcification that allows corals to build these immense structures has been extensively investigated, we still know little about the evolutionary processes that allowed the soft-bodied ancestor of corals to become the ecosystem builders they are today. Using a combination of phylogenomics, proteomics, and immunohistochemistry, we show that scleractinian corals likely acquired the ability to calcify sometime between ∼308 and ∼265 Ma through a combination of lineage-specific gene duplications and the co-option of existing genes to the calcification process. Our results suggest that coral calcification did not require extensive evolutionary changes, but rather few coral-specific gene duplications and a series of small, gradual optimizations of ancestral proteins and their co-option to the calcification process.     

Cellular BRET assay suggests a conformational rearrangement of preformed TrkB/Shc complexes following BDNF-dependent activation

We developed a cellular Bioluminescent Resonance Energy Transfer (BRET) assay based on the interaction of TrkB fused to Renilla luciferase with the intracellular adaptor protein Shc fused to Enhanced Yellow Fluorescent Protein (EYFP). The TrkB agonist Brain Derived Neurotrophic Factor (BDNF) induced a maximum BRET signal as of 10 min with an EC₅₀ value of 1.4 nM, similar to the other endogenous agonists NT-3 and NT-4/5, 1.5 nM and 0.34 nM, respectively. Interestingly, measure of the BRET signal with increasing expression of Shc-EYFP, in the presence or absence of BDNF, suggested a conformational change of preformed TrkB/Shc complexes rather than Shc recruitment. Furthermore, the Y516F TrkB mutant deficient to bind Shc as well as the kinase-dead K572R TrkB mutant was unable to respond to BDNF and exhibited a lower basal BRET signal than that of the wild-type TrkB receptor, again suggesting a preformed complex with constitutive activity. The double YY706/707FF TrkB mutant in the kinase activation loop also showed reduced basal activity but surprisingly kept its capacity to enhance BDNF-induced interaction with Shc, though with less efficacy. The Trk selective kinase inhibitors K252a and BMS-9 blocked BDNF-induced BRET signal with similar potency (100–150 nM), the preferential c-Met inhibitor PF-2341006 being one order of magnitude less potent. Remarkably, in the absence of BDNF, K252a and BMS-9 also reduced basal activity to the level of the Y516F TrkB mutant, suggesting that these compounds were able to reduce the TrkB constitutive activity. BRET responses of mutants and to kinase inhibitors thus reveal a complex level of interaction between TrkB and Shc and suggest that this BRET assay could be of great utility to test blockers of TrkB signalling in a physiologically relevant context.     

Modern and fossil non-pollen palynomorphs from the Basque mountains (western Pyrenees, France): the use of coprophilous fungi to reconstruct pastoral activity

This paper presents results from a modern dataset of non-pollen palynomorphs and its application to a ca. 2,000 year peat record from the same area in the western Pyrenees (Basque Country, France). The modern dataset is composed of 35 surface samples (moss polsters) from a mountainous pasture-woodland landscape. Airborne fungal spores (ascospores and conidia), found dominant in the dataset, are linked to the degree of landscape openness and grazing pressure. The complete spectrum of 13 selected spore-types of dung-related Ascomycetes is positively linked with grazing pressure. However, different dung affinities between the spore-types have been identified. These are types clearly related to high grazing pressure and types with no or unclear dung indicative value. The modern dataset is used to aid interpretation of the local fossil pollen record as an independent ‘proxy’ to assess past pastoral dynamics. This study confirms the utility of modern non-pollen palynomorphs from terrestrial ecosystems in the reconstruction of historical local pastoral activities but also shows their limitation. It may be necessary to extend such study to wetland ecosystems and to investigate the spatial dimension of some fungal spores.     

Activation of the l,d‐transpeptidation peptidoglycan cross‐linking pathway by a metallo‐d,d‐carboxypeptidase in Enterococcus faecium

Bypass of the penicillin‐binding proteins by an l ,d ‐transpeptidase (Ldt_fm) confers cross‐resistance to β‐lactam and glycopeptide antibiotics in mutants of Enterococcus faecium selected in vitro. Ldt_fm is produced by the parental strain D344S although it insignificantly contributes to peptidoglycan cross‐linking as pentapeptide stems cannot be used as acyl donors by this enzyme. Here we show that production of the tetrapeptide substrate of Ldt_fm is controlled by a two‐component regulatory system (DdcRS) and a metallo‐d ,d ‐carboxypeptidase (DdcY). The locus was silent in D344S and its activation was due to amino acid substitutions in DdcS or DdcR that led to production of DdcY and hydrolysis of the C‐terminal d ‐Ala residue of the cytoplasmic peptidoglycan precursor UDP‐MurNAc‐pentapeptide. The T¹⁶¹A and T¹⁶¹M substitutions affected a position of DdcS known to be essential for the phosphatase activity of related sensor kinases. Complete elimination of UDP‐MurNAc‐pentapeptide, which was required specifically for resistance to glycopeptides, involved substitutions in DdcY that increased the catalytic efficiency of the enzyme (E¹²⁷K) and affected its interaction with the cell envelope (I¹⁴N). The ddc locus displays striking similarities with portions of the van vancomycin resistance gene clusters, suggesting possible routes of emergence of cross‐resistance to glycopeptides and β‐lactams in natural conditions.     

Identification and functional implication of a Rho kinase-dependent moesin-EBP50 interaction in noradrenaline-stimulated artery

Ezrin, radixin, and moesin (ERM) proteins are known to be substrates of Rho kinase (ROCK), a key player in vascular smooth muscle regulation. Their function in arteries remains to be elucidated. The objective of the present study was to investigate ERM phosphorylation and function in rat aorta and mesenteric artery and the influence of ERM-binding phosphoprotein 50 (EBP50), a scaffold partner of ERM proteins in several cell types. In isolated arteries, ERM proteins are phosphorylated by PKC and ROCK with different kinetics after either agonist stimulation or KCl-induced depolarization. Immunoprecipitation of EBP50 in noradrenaline-stimulated arteries allowed identification of its interaction with moesin and several other proteins involved in cytoskeleton regulation. This interaction was inhibited by Y27632, a ROCK inhibitor. Moesin or EBP50 depletion after small interfering RNA transfection by reverse permeabilization in intact mesenteric arteries both potentiated the contractility in response to agonist stimulation without any effect on contractile response induced by high KCl. This effect was preserved in ionomycin-permeabilized arteries. These results indicate that, in agonist-stimulated arteries, the activation of ROCK leads to the binding of moesin to EBP50, which interacts with several components of the cytoskeleton, resulting in a decrease in the contractile response.     

Wound healing and arm regeneration in Ophioderma longicaudum and Amphiura filiformis (Ophiuroidea, Echinodermata): comparative morphogenesis and histogenesis

All species of the Ophiuroidea have exceptional regenerative capabilities; in particular, they can replace arms lost following traumatic or self-induced amputation. In order to reconstruct this complex phenomenon, we studied arm regeneration in two different ophiuroids, Ophioderma longicaudum (Retzius, 1805) and Amphiura filiformis O. F. Müller, 1776, which are quite distantly related. These species present contrasting regeneration and differentiation rates and differ in several ecological traits. The aim of this paper is to interpret the primary sequence of morphogenetic and histogenetic events leading to the complete reconstruction of a new arm, comparing the arm regenerative processes of these two ophiuroid species with those described in crinoids. Arm regeneration in ophiuroids is considered an epimorphic process in which new structures develop from a typical blastema formed from an accumulation of presumptive undifferentiated cells. Our results showed that although very different in some respects such as, for instance, the regeneration rate (0.17 mm/week for O. longicaudum and 0.99 mm/week for A. filiformis), morphogenetic and histogenetic aspects are surprisingly similar in both species. The regenerative process presents similar characteristics and follows a developmental scheme which can be subdivided into four phases: a repair phase, an early regenerative phase, an intermediate regenerative phase and an advanced regenerative phase. In terms of histogenesis, the regenerative events involve the development of new structures from migratory pluripotent cells, which proliferate actively, in addition in both cases there is a significant contribution from dedifferentiated cells, in particular dedifferentiating myocytes, although to varying extents. This evidence confirms the plasticity of the regenerative phenomenon in echinoderms, which can apparently follow different pathways in terms of growth and morphogenesis, but nevertheless involve both epimorphic and morphallactic contributions at the cellular level.