Project description:Resident microorganisms (microbiota) have far-reaching effects on the biology of their animal hosts, with major consequences for the host’s health and fitness. Some of these effects can be explained by microbial impacts on the expression of individual genes but a full understanding of microbiota-dependent gene regulation requires analysis of the overall architecture of the host transcriptome. In this study, we investigated the impact of the microbiota on the global structure of the transcriptome of Drosophila. Our transcriptomic analysis of 17 Drosophila lines representative of the global genetic diversity of this species yielded a total of 11 transcriptional modules of co-expressed genes. For 7 of these modules, the strength of the transcriptional network (defined as gene-gene coexpression) differed significantly between flies bearing a defined gut microbiota (gnotobiotic flies) and flies reared under microbiologically-sterile conditions (axenic flies). Furthermore, the network structure was uniformly stronger in these microbiota-dependent modules than in both the microbiota-independent modules in gnotobiotic flies and all modules in axenic flies, indicating that the presence of the microbiota tightens gene regulation in a subset of the transcriptome. The genes constituting the microbiota-dependent transcriptional modules include regulators of growth, metabolism and neurophysiology, previously implicated in mediating phenotypic effects of microbiota on Drosophila phenotype. Together these results provide the key first evidence that the microbiota strengthens the co-expression of genesin specific networks of functionally-related transcripts relative to the animal’s intrinsic baseline level of co-expression. Our system-wide analysis demonstrates that the presence of microbiota enhances the structure of the transcriptional network in the animal host. This finding has potentially major implications for understanding of the mechanisms by which microbiota affect host health and fitness, and the ways in which hosts and their resident microbiota coevolve.
Project description:Nucleus is a highly structured organelle and contains many functional compartments. While the structural basis for this complex spatial organization of compartments is unknown, a major component of this organization is likely to be the non-chromatin scaffolding called nuclear matrix (NuMat). Experimental evidence over the past decades indicates that most of the nuclear functions are at least transiently associated with the NuMat although the components of NuMat itself are poorly known. Here, we report NuMat proteome analysis from Drosophila melanogaster embryos and discuss its links with nuclear architecture and functions. In the NuMat proteome, we find structural proteins, chaperones related, DNA/RNA binding, chromatin remodeling and transcription factors. This complexity of NuMat proteome is an indicator of its structural and functional significance. Comparison of the 2D profile of NuMat proteome from different developmental stages of Drosophila embryos shows that less than half of the NuMat proteome is constant and rest of the proteins are stage specific dynamic components. This NuMat dynamics suggests a possible functional link between NuMat and the embryonic development. Finally, we also show that a subset of NuMat proteins remain associated with the mitotic chromosomes implicating their role in mitosis and possibly the epigenetic cellular memory. NuMat proteome analysis provides tools and opens up ways to understand nuclear organization and function.