ALBERT

Description: A core promoter is a stretch of DNA surrounding the transcription start site (TSS) that integrates regulatory inputs and recruits general transcription factors to initiate transcription. The nature and causative relationship of the DNA sequence and chromatin signals that govern the selection of most TSSs by RNA polymerase II remain unresolved. Maternal to zygotic transition represents the most marked change of the transcriptome repertoire in the vertebrate life cycle. Early embryonic development in zebrafish is characterized by a series of transcriptionally silent cell cycles regulated by inherited maternal gene products: zygotic genome activation commences at the tenth cell cycle, marking the mid-blastula transition. This transition provides a unique opportunity to study the rules of TSS selection and the hierarchy of events linking transcription initiation with key chromatin modifications. We analysed TSS usage during zebrafish early embryonic development at high resolution using cap analysis of gene expression, and determined the positions of H3K4me3-marked promoter-associated nucleosomes. Here we show that the transition from the maternal to zygotic transcriptome is characterized by a switch between two fundamentally different modes of defining transcription initiation, which drive the dynamic change of TSS usage and promoter shape. A maternal-specific TSS selection, which requires an A/T-rich (W-box) motif, is replaced with a zygotic TSS selection grammar characterized by broader patterns of dinucleotide enrichments, precisely aligned with the first downstream (+1) nucleosome. The developmental dynamics of the H3K4me3-marked nucleosomes reveal their DNA-sequence-associated positioning at promoters before zygotic transcription and subsequent transcription-independent adjustment to the final position downstream of the zygotic TSS. The two TSS-defining grammars coexist, often physically overlapping, in core promoters of constitutively expressed genes to enable their expression in the two regulatory environments. The dissection of overlapping core promoter determinants represents a framework for future studies of promoter structure and function across different regulatory contexts.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Haberle, Vanja -- Li, Nan -- Hadzhiev, Yavor -- Plessy, Charles -- Previti, Christopher -- Nepal, Chirag -- Gehrig, Jochen -- Dong, Xianjun -- Akalin, Altuna -- Suzuki, Ana Maria -- van IJcken, Wilfred F J -- Armant, Olivier -- Ferg, Marco -- Strahle, Uwe -- Carninci, Piero -- Muller, Ferenc -- Lenhard, Boris -- MC_UP_1102/1/Medical Research Council/United Kingdom -- Medical Research Council/United Kingdom -- England -- Nature. 2014 Mar 20;507(7492):381-5. doi: 10.1038/nature12974. Epub 2014 Feb 16.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Department of Biology, University of Bergen, Thormohlensgate 53A, N-5008 Bergen, Norway [2] Institute of Clinical Sciences and MRC Clinical Sciences Center, Faculty of Medicine, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK [3]. ; 1] School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK [2]. ; School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. ; 1] RIKEN Omics Science Center, Yokohama, Kanagawa 230-0045, Japan [2] RIKEN Center for Life Science Technologies, Division of Genomic Technologies, RIKEN Yokohama Campus, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan. ; 1] Computational Biology Unit, Uni Computing, Uni Research AS, University of Bergen, Thormohlensgate 55, N-5008 Bergen, Norway [2] German Cancer Research Center (DKFZ), Genomics & Proteomics Core Facility (GPCF), Im Neuenheimer Feld 580/TP3, Heidelberg 69120, Germany (C.Pr.); Broegelmann Research Laboratory, The Gade Institute, University of Bergen, The Laboratory Building, Haukeland University Hospital, N-5021 Bergen, Norway (C.N.); Acquifer AG, Sophienstrasse 136, 76135 Karlsruhe, Germany (J.G.); Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA (X.D.); Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland (A.A.). ; 1] School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK [2] German Cancer Research Center (DKFZ), Genomics & Proteomics Core Facility (GPCF), Im Neuenheimer Feld 580/TP3, Heidelberg 69120, Germany (C.Pr.); Broegelmann Research Laboratory, The Gade Institute, University of Bergen, The Laboratory Building, Haukeland University Hospital, N-5021 Bergen, Norway (C.N.); Acquifer AG, Sophienstrasse 136, 76135 Karlsruhe, Germany (J.G.); Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA (X.D.); Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland (A.A.). ; Erasmus Medical Center, Center for Biomics, Room Ee679b, Dr Molewaterplein 50, 3015 GE Rotterdam, The Netherlands. ; Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Postfach 3640, 76021 Karlsruhe, Germany. ; 1] Institute of Clinical Sciences and MRC Clinical Sciences Center, Faculty of Medicine, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK [2] Department of Informatics, University of Bergen, Thormohlensgate 55, N-5008 Bergen, Norway.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24531765" target="_blank"〉PubMed〈/a〉

Description: 〈p〉To examine the contributions of impaired gut microbial community development to childhood undernutrition, we combined metabolomic and proteomic analyses of plasma samples with metagenomic analyses of fecal samples to characterize the biological state of Bangladeshi children with severe acute malnutrition (SAM) as they transitioned, after standard treatment, to moderate acute malnutrition (MAM) with persistent microbiota immaturity. Host and microbial effects of microbiota-directed complementary food (MDCF) prototypes targeting weaning-phase bacterial taxa underrepresented in SAM and MAM microbiota were characterized in gnotobiotic mice and gnotobiotic piglets colonized with age- and growth-discriminatory bacteria. A randomized, double-blind controlled feeding study identified a lead MDCF that changes the abundances of targeted bacteria and increases plasma biomarkers and mediators of growth, bone formation, neurodevelopment, and immune function in children with MAM.〈/p〉

Description: 〈p〉Characterizing the organization of the human gut microbiota is a formidable challenge given the number of possible interactions between its components. Using a statistical approach initially applied to financial markets, we measured temporally conserved covariance among bacterial taxa in the microbiota of healthy members of a Bangladeshi birth cohort sampled from 1 to 60 months of age. The results revealed an "ecogroup" of 15 covarying bacterial taxa that provide a concise description of microbiota development in healthy children from this and other low-income countries, and a means for monitoring community repair in undernourished children treated with therapeutic foods. Features of ecogroup population dynamics were recapitulated in gnotobiotic piglets as they transitioned from exclusive milk feeding to a fully weaned state consuming a representative Bangladeshi diet.〈/p〉