Structure and dynamics of the operon map of Buchnera aphidicola sp. strain APS

<p>Abstract</p> <p>Background</p> <p>Gene expression regulation is still poorly documented in bacteria with highly reduced genomes. Understanding the evolution and mechanisms underlying the regulation of gene transcription in <it>Buchnera aphidicola</it>, the primary endosymbiont of aphids, is expected both to enhance our understanding of this nutritionally based association and to provide an intriguing case-study of the evolution of gene expression regulation in a reduced bacterial genome.</p> <p>Results</p> <p>A Bayesian predictor was defined to infer the <it>B. aphidicola </it>transcription units, which were further validated using transcriptomic data and RT-PCR experiments. The characteristics of <it>B. aphidicola </it>predicted transcription units (TUs) were analyzed in order to evaluate the impact of operon map organization on the regulation of gene transcription.</p> <p>On average, <it>B. aphidicola </it>TUs contain more genes than those of <it>E. coli</it>. The global layout of <it>B. aphidicola </it>operon map was mainly shaped by the big reduction and the rearrangements events, which occurred at the early stage of the symbiosis. Our analysis suggests that this operon map may evolve further only by small reorganizations around the frontiers of <it>B. aphidicola </it>TUs, through promoter and/or terminator sequence modifications and/or by pseudogenization events. We also found that the need for specific transcription regulation exerts some pressure on gene conservation, but not on gene assembling in the operon map in <it>Buchnera</it>. Our analysis of the TUs spacing pointed out that a selection pressure is maintained on the length of the intergenic regions between divergent adjacent gene pairs.</p> <p>Conclusions</p> <p><it>B. aphidicola </it>can seemingly only evolve towards a more polycistronic operon map. This implies that gene transcription regulation is probably subject to weak selection pressure in <it>Buchnera </it>conserving operons composed of genes with unrelated functions.</p

The human body at cellular resolution: the NIH Human Biomolecular Atlas Program

Abstract: Transformative technologies are enabling the construction of three-dimensional maps of tissues with unprecedented spatial and molecular resolution. Over the next seven years, the NIH Common Fund Human Biomolecular Atlas Program (HuBMAP) intends to develop a widely accessible framework for comprehensively mapping the human body at single-cell resolution by supporting technology development, data acquisition, and detailed spatial mapping. HuBMAP will integrate its efforts with other funding agencies, programs, consortia, and the biomedical research community at large towards the shared vision of a comprehensive, accessible three-dimensional molecular and cellular atlas of the human body, in health and under various disease conditions