Browsing School, Graduate by Subject "16S rRNA"
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THE BACTERIAL COMMUNITIES ASSOCIATED WITH TWO MARINE SPONGES OF THE GENUS XESTOSPONGIAMarine sponges are sessile, filter-feeding, multicellular invertebrates that host diverse assemblages of microbial organisms, including bacteria, diatoms, and fungi. Marine sponges and their microbial associations are important in the field of drug discovery, and are models for studying the complex symbioses that exist between eukaryotes and bacteria. The bacterial communities associated with Xestospongia muta from the Florida Keys and Xestospongia testudinaria from Indonesia were being compared to reveal key symbionts that are important to these sponges. These two sponge species have been separated for millions of years and some groups of bacteria will have been maintained for this time because they have important roles as symbionts. We hypothesize that the bacterial communities associated with giant barrel sponges of the genus Xestospongia have a characteristic composition that includes novel species. Based on these observations, the experimental focus of this proposal is on in-depth analysis of the bacterial communities associated with Xestospongia spp. sponges. Both molecular and culture-based techniques are used to characterize and compare the bacterial symbionts of X. muta and X. testudinaria.
The Effect of Live-attenuated and Wild-type Shigella Strains on the Gastrointestinal Microbiota in Cynomolgus MacaquesLittle is known about the role of the gastrointestinal microbiota in susceptibility to infection with enteric pathogens and response to live oral vaccines. This study examined the effect of immunization with an oral live-attenuated Shigella dysenteriae 1 vaccine and challenge with wild-type S. dysenteriae 1 on the gastrointestinal microbiota of cynomolgus macaques using 16S rRNA analysis. Multi-dimensional cluster analysis identified distinct bacterial community types within healthy macaques. The microbiota found in association with Mauritian macaques is distinct from and characterized by significantly higher diversity than the microbiota found in macaques from other geographic origins. Mauritian macaques also contain genetically distinct microsatellites in loci spanning the major histocompatibility complex (MHC) region, providing a possible link between the MHC repertoire and the intestinal microbiota. The intestinal microbiota in distinct macaque populations responds differently to immunization and subsequent challenge with wild-type Shigella, and is altered in fecal samples collected post-immunization and post-challenge in macaques from Indonesia, Indochina and the Philippines, but not from Mauritius. Specifically, Shigella exposure results in the appearance of a community type that is dominated by Enterococcus, a genus typically present at low abundance. While both Mauritian and non-Mauritian macaques exhibit anti-Shigella antibody responses upon immunization and challenge, clinical symptoms of shigellosis post-challenge are only observed in non-Mauritian macaques. These studies highlight the importance of further investigation into the possible protective role of the microbiota against enteric pathogens and the importance of host genetic backgrounds in conducting vaccine studies.