Microbiota of the Gut-Lymph Node Axis: Depletion of Mucosa-Associated Segmented Filamentous Bacteria and Enrichment of Methanobrevibacter by Colistin Sulfate and Linco-Spectin in Pigs

Microorganisms are translocated from the gut to lymphatic tissues via immune cells, thereby challenging and training the mammalian immune system. Antibiotics alter the gut microbiome and consecutively might also affect the corresponding translocation processes, resulting in an imbalanced state between the intestinal microbiota and the host. Hence, understanding the variant effects of antibiotics on the microbiome of gut-associated tissues is of vital importance for maintaining metabolic homeostasis and animal health. In the present study, we analyzed the microbiome of (i) pig feces, ileum, and ileocecal lymph nodes under the influence of antibiotics (Linco-Spectin and Colistin sulfate) using 16S rRNA gene sequencing for high-resolution community profiling and (ii) ileocecal lymph nodes in more detail with two additional methodological approaches, i.e., cultivation of ileocecal lymph node samples and (iii) metatranscriptome sequencing of a single lymph node sample. Supplementation of medicated feed showed a local effect on feces and ileal mucosa-associated microbiomes. Pigs that received antibiotics harbored significantly reduced amounts of segmented filamentous bacteria (SFB) along the ileal mucosa (p = 0.048; 199.17-fold change) and increased amounts of Methanobrevibacter, a methanogenic Euryarchaeote in fecal samples (p = 0.005; 20.17-fold change) compared to the control group. Analysis of the porcine ileocecal lymph node microbiome exposed large differences between the viable and the dead fraction of microorganisms and the microbiome was altered to a lesser extent by antibiotics compared with feces and ileum. The core microbiome of lymph nodes was constituted mainly of Proteobacteria. RNA-sequencing of a single lymph node sample unveiled transcripts responsible for amino acid and carbohydrate metabolism as well as protein turnover, DNA replication and signal transduction. The study presented here is the first comparative study of microbial communities in feces, ileum, and its associated ileocecal lymph nodes. In each analyzed site, we identified specific phylotypes susceptible to antibiotic treatment that can have profound impacts on the host physiological and immunological state, or even on global biogeochemical cycles. Our results indicate that pathogenic bacteria, e.g., enteropathogenic Escherichia coli, could escape antibiotic treatment by translocating to lymph nodes. In general ileocecal lymph nodes harbor a more diverse and active community of microorganisms than previously assumed

Short-Chain Fatty Acids Modulate Permeability, Motility and Gene Expression in the Porcine Fetal Jejunum Ex Vivo

Postnatally, short-chain fatty acids (SCFA) are important energetic and signaling agents, being involved in host nutrition, gut imprinting and immune and barrier function. Whether SCFA exert similar effects during the late fetal phase has been insufficiently elucidated. This study aimed to evaluate whether the fetal jejunum senses SCFA and whether SCFA modify the muscle tension and epithelial permeability and related signaling in jejunal tissue from the porcine fetus in late gestation. Exposure of fetal jejunal tissue to a mix of SCFA (70 µmol/mL) in an organ bath for 20 min lowered the muscle tension. Moreover, SCFA decreased the transepithelial conductance while increasing the short-circuit current in the Ussing chamber, indicating reduced permeability and increased SCFA absorption. Gene expression in the tissues harvested from the Ussing chamber after 30 min indicated downregulation of the expression of receptors (i.e., FFAR2 and TLR2), MCT1 and tight-junction and adherens proteins, which may be a negative feedback response to the applied high SCFA concentration compared with the micromolar concentration detected in fetal gastric fluid. Taken together, our data demonstrate that the fetal jejunum senses SCFA, which trigger electrophysiological, muscle contraction and related gene transcription responses. Hence, SCFA may play a role in prenatal gut nutrition and imprinting

Glutathione peroxidase 4 and vitamin E control reticulocyte maturation, stress erythropoiesis and iron homeostasis

Glutathione peroxidase 4 (GPX4) is unique as it is the only enzyme that can prevent detrimental lipid peroxidation in vivo by reducing lipid peroxides to the respective alcohols thereby stabilizing oxidation products of unsaturated fatty acids. During reticulocyte maturation, lipid peroxidation mediated by 15-lipoxygenase in humans and rabbits and by 12/15-lipoxygenase (ALOX15) in mice was considered the initiating event for the elimination of mitochondria but is now known to occur through mitophagy. Yet, genetic ablation of the Alox15 gene in mice failed to provide evidence for this hypothesis. We designed a different genetic approach to tackle this open conundrum. Since either other lipoxygenases or non-enzymatic autooxidative mechanisms may compensate for the loss of Alox15, we asked whether ablation of Gpx4 in the hematopoietic system would result in the perturbation of reticulocyte maturation. Quantitative assessment of erythropoiesis indices in the blood, bone marrow (BM) and spleen of chimeric mice with Gpx4 ablated in hematopoietic cells revealed anemia with an increase in the fraction of erythroid precursor cells and reticulocytes. Additional dietary vitamin E depletion strongly aggravated the anemic phenotype. Despite strong extramedullary erythropoiesis reticulocytes failed to mature and accumulated large autophagosomes with engulfed mitochondria. Gpx4-deficiency in hematopoietic cells led to systemic hepatic iron overload and simultaneous severe iron demand in the erythroid system. Despite extremely high erythropoietin and erythroferrone levels in the plasma, hepcidin expression remained unchanged. Conclusively, perturbed reticulocyte maturation in response to Gpx4 loss in hematopoietic cells thus causes ineffective erythropoiesis, a phenotype partially masked by dietary vitamin E supplementation.ISSN:0390-6078ISSN:1592-872

Responses of flowering phenology of snowbed plants to an experimentally imposed extreme advanced snowmelt

In snowbed habitats, characterized by a long-lasting snow cover, the timing of snowmelt can be included among the major factors controlling plant phenology. Nevertheless, only a few ecological studies have tested the responses of flowering phenology of species growing in very late snow-free habitats to an advanced snowmelt (AS) date. The aim of this study was to determine the impacts of an extremely earlier melt-out of snow on flowering phenology of vascular plant species inhabiting an alpine snowbed. The study was conducted in the high Gavia Valley (Italy, 2,700 m a.s.l.). On 30th May 2012, we removed manually the snow cover and set up an experiment with 5 AS and 5 control plots. Phenological observations of the most abundant vascular species were conducted every 4–6 days. Moreover, we calculated cumulative soil temperature and recorded the mortality of reproductive structures of three species. For several species flowering occurred earlier, and the prefloration period was extended in the AS treatment in comparison with the control. For the majority of species, cumulative soil temperatures in the AS treatment and the control were comparable, confirming that temperature exerts the main control on the flowering of the species inhabiting snowbeds. Earlier flowering species resulted more affected by an AS date in comparison with later flowering species. The mortality of reproductive structures did not increase in the AS treatments in comparison with the control suggesting that few and weak frost events in late spring do not affect the survival of reproductive structures of the species studied

Winter climate change, plant traits and nutrient and carbon cycling in cold biomes

It is essential that scientists be able to predict how strong climate warming, including profound changes to winter climate, will affect the ecosystem services of alpine, arctic and boreal areas, and how these services are driven by vegetation-soil feedbacks. One fruitful avenue for studying such changing feedbacks is through plant functional traits, as an understanding of these traits may help us to understand and synthesise (1) responses of vegetation (through 'response traits' and 'specific response functions' of each species) to winter climate and (2) the effects of changing vegetation composition (through 'effect traits' and 'specific effect functions' of each species) on soil functions. It is the relative correspondence of variation in response and effect traits that will provide useful data on the impacts of winter climate change on carbon and nutrient cycling processes. Here we discuss several examples of how the trait-based, response-effect framework can help scientists to better understand the effects of winter warming on key ecosystem functions in cold biomes. These examples support the view that measuring species for their response and effect traits, and how these traits are linked across species through correspondence of variation in specific response and effects functions, may be a useful approach for teasing out the contribution of changing vegetation composition to winter warming effects on ecosystem functions. This approach will be particularly useful when linked with ecosystem-level measurements of vegetation and process responses to winter warming along natural gradients, over medium time scales in given sites or in response to experimental climate manipulations. © 2013 The Ecological Society of Japan

On a further search for a yearly modulation of the rate in particle Dark Matter direct search

DAMA collaborationConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro,7, Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal