Project description:It is increasingly recognised that the gastrointestinal microbiota plays a critical role in human health and promising evidence is accumulating that with dietary strategies, of prebiotic intervention, microbiota imbalances can be corrected and host health improved. Several prebiotics are widely used commercially in foods including inulin, fructo-oligosaccharides, galacto-oligosaccharides and resistant starches and there is convincing evidence, in particular for galacto-oligosaccharides, that prebiotics can modulate the microbiota and promote the growth of bifidobacteria in the intestinal tract of infants and adults. In this study we describe the identification and functional characterisation of the genetic loci responsible for the transport and metabolism of purified galacto-oligosaccharides (PGOS) by our model bifidobacterial strain, B. breve UCC2003. We further demonstrate that the extracellular endogalactanase specified by several B. breve strains, including B. breve UCC2003, is essential for metabolism of PGOS components with a long retention time and high degree of polymerisation. These PGOS components are transported into the bifidobacterial cell via various ABC transport systems and sugar permeases where they are further metabolised to galactose and glucose monomers that feed into the bifid shunt. This research described here advances our understanding of GOS metabolism by bifidobacteria and for the future there is great potential for exploiting bifidobacterial beta-galactosidase to create targeted prebiotics that can enrich for selected Bifiobacteria sp. and other beneficial microbes among the gut microbiota.
Project description:The factors that govern the retention and abundance of specific microbial lineages within a developing intestinal microbiota remain poorly defined. Human milk oligosaccharides consumed by nursing infnats pass undigested to the distal gut where they may be consumed by microbes. We investigated the transcriptional response of Bacterides fragilis, a prominent gut resident, to the presence of HMOs. In vitro transcriptional profiles of Bacteroides fragilis obtained from biological duplicate cultures taken at middle log phase in minimal media glucose (MM-Glu) and in minimal media with human milk oligosaccharides (MM-HMO).
Project description:Endurance exercise has a dramatic impact on the functionality of mitochondria and on the composition of intestinal microbiome, but the mechanisms regulating the crosstalk between these two components are still largely unknown. Here, we sampled 20 elite horses before and after an endurance race and used blood transcriptome, blood metabolome and fecal microbiome to describe the microbiota-mitochondria inter-talk. A subset of mitochondria-related differentially expressed genes involved in pathways such as energy metabolism, oxidative stress and inflammation was discovered and then shown to be associated with butyrate-producing bacteria of the Lachnospiraceae family, especially Eubacterium. The mechanisms involved were not fully understood, but through the action of their metabolites likely acted on PPARδ, the FRX-CREB axis and their downstream targets to delay the onset of hypoglycemia, inflammation and extend running time. Our results also suggested that circulating free fatty acids may act not merely as fuel but drive mitochondrial inflammatory responses triggered by the translocation of gut bacterial polysaccharides following endurance. Targeting the gut-mitochondria axis appears therefore as a potential strategy to enhance athletic performance.
Project description:The factors that govern the retention and abundance of specific microbial lineages within a developing intestinal microbiota remain poorly defined. Human milk oligosaccharides consumed by nursing infnats pass undigested to the distal gut where they may be consumed by microbes. We investigated the transcriptional response of Bacterides fragilis, a prominent gut resident, to the presence of HMOs.
Project description:With this study, we wanted to investigate degradation of human milk oligosaccharides and the subsequent cross-feeding interactions of a complex bacterial community that resembles the gut microbiota of pre-weaned vaginally-born breastfed infants.
Project description:Maternal secretor status is one of the determinants of human milk oligosaccharides (HMOs) composition, which in turn changes the gut microbiota composition of infants. To understand if this change in gut microbiota impacts immune cell composition, intestinal morphology and gene expression, day 21-old germ-free mice were transplanted with fecal microbiota from infants whose mothers were either secretors (SMM) or non-secretors (NSM) or from infants consuming dairy-based formula (MFM). For each group, one set of mice was supplemented with HMOs. HMO supplementation did not significantly impact the microbiota diversity however, SMM mice had higher abundance of genus Bacteroides, Bifidobacterium, and Blautia, whereas, in the NSM group, there were higher abundance of Akkermansia, Enterocloster, and Klebsiella. In MFM, gut microbiota was represented mainly by Parabacteroides, Ruminococcaceae_unclassified, and Clostrodium_sensu_stricto. In mesenteric lymph node, Foxp3+ T cells and innate lymphoid cells type 2 (ILC2) were increased in MFM mice supplemented with HMOs while in the spleen, they were increased in SMM+HMOs mice. Similarly, serum immunoglobulin A (IgA) was also elevated in MFM+HMOs group. Distinct global gene expression of the gut was observed in each microbiota group, which was enhanced with HMOs supplementation. Overall, our data shows that distinct infant gut microbiota due to maternal secretor status or consumption of dairy-based formula and HMO supplementation impacts immune cell composition, antibody response and intestinal gene expression in a mouse model.
Project description:The adaptive response to extreme endurance exercise might involve transcriptional and translational regulation by microRNAs (miRNAs). Therefore, the aim of this study was to define an integrative analysis of blood transcriptome and miRNome in horses before and after a long endurance ride (160 km) using equine microarrays. A total of 2,453 genes and 162 miRNAs were found to be differentially expressed (DEG) between animals at rest and after the endurance ride. To gain understanding of the biological functions regulated by the differentially expressed miRNA, we used a hypergeometric test analysis. Notably, we detected 42 differentially expressed miRNAs that putatively regulate a total of 350 depleted DEGs, involved in glucose metabolism, fatty acid oxidation, mitochondrion biogenesis, and immune response pathways. Graphical Gaussian models in an independent validation set of animals confirmed that 4 miRNAs could be strong candidate regulatory molecules for endurance exercise adaptation. This study represents, to the best of our knowledge, the first integrated comprehensive overview of the miRNA-mRNA co-regulation networks that may play a central role in controlling post-transcriptomic regulations during endurance exercise in horses.
Project description:Age-related declines in cardiorespiratory fitness and physical function are mitigated by regular endurance exercise in older adults. This may be due, in part, to changes in the transcriptional program of skeletal muscle following repeated bouts of exercise. However, the impact of chronic exercise training on the transcriptional response to an acute bout of endurance exercise has not been clearly determined. Here, we characterized baseline differences in muscle transcriptome and exercise-induced response in older adults who were active/endurance trained or sedentary. RNA-sequencing was performed on vastus lateralis biopsy specimens obtained before, immediately after, and 3 h following a bout of endurance exercise (40 min of cycling at 60%–70% of heart rate reserve). Using a recently developed bioinformatics approach, we found that transcript signatures related to type I myofibers, mitochondria, and endothelial cells were higher in active/endurance-trained adults and were associated with key phenotypic features including V̇o2peak, ATPmax, and muscle fiber proportion. Immune cell signatures were elevated in the sedentary group and linked to visceral and intermuscular adipose tissue mass. Following acute exercise, we observed distinct temporal transcriptional signatures that were largely similar among groups. Enrichment analysis revealed catabolic processes were uniquely enriched in the sedentary group at the 3-h postexercise timepoint. In summary, this study revealed key transcriptional signatures that distinguished active and sedentary adults, which were associated with difference in oxidative capacity and depot-specific adiposity. The acute response signatures were consistent with beneficial effects of endurance exercise to improve muscle health in older adults irrespective of exercise history and adiposity.
Project description:Exercise is a fundamental component of human health that is associated with greater life expectancy and reduced risk of chronic diseases. While the beneficial effects of endurance exercise on human health are well established, the molecular mechanisms responsible for these observations remain unclear. Endurance exercise reduces the accumulation of mitochondrial DNA (mtDNA) mutations, alleviates multisystem pathology, and increases the lifespan of the mtDNA mutator mouse model of aging, in which the proof-reading capacity of mitochondrial polymerase gamma (POLG1) is deficient. Clearly, exercise recruited a POLG1-independent mtDNA repair pathway to induce these adaptations, a novel finding as POLG1 is canonically considered to be the sole mtDNA repair enzyme. Here we investigate the identity of this pathway, and show that endurance exercise prevents mitochondrial oxidative damage, attenuates telomere erosion, and mitigates cellular senescence and apoptosis in mtDNA mutator mice. Unexpectedly, we observe translocation of tumour suppressor protein p53 to mitochondria in response to endurance exercise that facilitates mtDNA mutation repair. Indeed, endurance exercise failed to prevent mtDNA mutations, induce mitochondrial biogenesis, preserve mitochondrial morphology, reverse sarcopenia, and mitigate premature mortality in mtDNA mutator mice with muscle-specific deletion of p53. Our data establish an exciting new role for p53 in exercise-mediated maintenance of the mtDNA genome, and presents mitochondrially-targeted p53 as a novel therapeutic modality for aging-associated diseases of mitochondrial etiology. Microarray analysis of gene expression from skeletal muscle (quadriceps femoris) from Mus musculus. N=23 samples per treatment were analysed for whole transcriptiome gene expression profile using NimbleGen Arrays. The treatment groups included wild-type C57Bl/6J mice as the control group, then two treatment groups which both contained homozygous knock-in mtDNA mutator mice (PolG; PolgAD257A/D257A). Once group of these heterozygous knock out mice received regular endurance exercise sessions while the other group remained sedentraty for 6 months. The control group specimens were wild-type litter mates to the transgenic knockout mice.