Project description:Chlamydiae are obligate intracellular bacteria comprising well-known human pathogens and ubiquitous symbionts of protists, which are characterized by a unique developmental cycle. Here we comprehensively analyzed gene expression dynamics of Protochlamydia amoebophila during infection of its Acanthamoeba host by RNA sequencing. This revealed a highly dynamic transcriptional landscape, where major transcriptional shifts are conserved among chlamydial symbionts and pathogens. Our data served to propose a time-resolved model for type III protein secretion during the developmental cycle, and we provide evidence for a biphasic metabolism of P. amoebophila during infection, which involves energy parasitism and amino acids as carbon source during initial stages and a post-replicative switch to endogenous glucose-based ATP production. This fits well with major transcriptional changes in the amoeba host, where upregulation of complex sugar breakdown precedes the P. amoebophila metabolic switch. The biphasic chlamydial metabolism represents a unique adaptation to exploit eukaryotic host cells, which likely contributed to the evolutionary success of this group of microbes.
Project description:Bathymodiolus mussels inhabiting deep-sea hydrothermal vents harbor bacterial symbionts in their gills, which support the animals’ diet. While the basic mechanisms of energy generation and CO2 fixation that drive these symbioses are largely established, details of molecular interactions between the symbiotic partners and adaptations to their respective habitats remain unknown. In this study, we therefore comparatively examined the genomes and proteomes of two Bathymodiolus hosts and their respective symbionts from different geographical locations. Two mussel species were proteomically compared: i) B. thermophilus mussel containing sulfur-oxidizing symbiont from the east pacific rise. thermophilus and ii) B. azoricus containing thiotrophic and methanotrophic symbionts from the mid-atlantic ridge. Symbionts (for both species) and host components (for B. azoricus) were selectively enriched using a multi-step centrifugation procedure. Enriched host and symbiont fractions along with unenriched gill foot tissue were subject to in-depth semi-quantitative proteomic analyses using the orbitrap and velos mass spectrometers. Proteins were quantified based on their spectral counts using the normalized spectral abundance factor (NSAF) method. We identified common strategies of metabolic interactions that provide mutual nutritional support between host and symbionts, such as the detoxification of ambient sulfide by the Bathymodiolus host, which provides a stable thiosulfate reservoir for the thiotrophic symbionts, and a putative amino acid cycling mechanism that could supply the host with symbiont-derived amino acids. A suite of genes and proteins putatively related to virulence or defense functions was particularly abundant in the B. thermophilus symbiont, compared to its symbiont relatives, and may pose a host species-specific adaptation. Our results reveal both, a high degree of integration between the symbiotic partners, and great potential to adapt to the prevailing environment, which facilitate the holobiont’s survival in its hydrothermal vent habitat.
Project description:Molecular basis for CNS dysfunction in simian immunodeficiency virus-infected rhesus monkeys. We used microarrays to identify differentially expressed genes in chronic simian immunodeficiency virus-infected rhesus monkeys.
Project description:Molecular basis for CNS dysfunction in simian immunodeficiency virus-infected rhesus monkeys. We used microarrays to identify differentially expressed genes in chronic simian immunodeficiency virus-infected rhesus monkeys. Frontal lobe samples were obtained from control and SIV infected animals for RNA extraction and hybridization on Affymetrix microarrays. We sought to better understand the gene that changes in gene expression with SIV infection in the frontal lobe.
Project description:Gene expression profiles of Bacteroides thetaiotaomicron in vitro during growth on host mucosal polysaccharides as sole carbon sources. All substrates in this series are derived from porcine gastric mucin and include mucin O-glycans and glycosaminoglycans. Two different culture formats used: 800ml batch-culture bioreactors and 5ml tube cultures (format is indicated within each sample title). Each set of growths was referenced to a minimal medium glucose reference corressponding to the same culture format. Unfractionated porcine mucosal glycan (PMG) growths were compared to previously published in vivo datasets, which were referenced to the 800ml minimal medium glucose reference dataset.