Query: NC_008043:167108 Silicibacter sp. TM1040 mega plasmid, complete sequence
Lineage: Ruegeria; Ruegeria; Rhodobacteraceae; Rhodobacterales; Proteobacteria; Bacteria
General Information: This strain was isolated from a culture of the dinoflagellate Pfiesteria piscicida CCMP1830 which has been implicated in many large scale algal blooms resulting in increased mortality in fish. The bacteria are attached to the surface of the dinoflagellate and in some ways allow the dinoflagellate to grow as those lacking the bacteria die off. The bacterium also chemotaxes towards the dinoflagellate product DMSP (dimethylsulfoniopropionate) and metabolizes it. DMSP is a major source of sulfur in marine ecosystems and plays a role in the sulfur biogeochemical cycle. The implication is a tight association between these important dinoflagellates and this marine bacterium.
Subject: NC_000921:1007519 Helicobacter pylori J99, complete genome
Lineage: Helicobacter pylori; Helicobacter; Helicobacteraceae; Campylobacterales; Proteobacteria; Bacteria
General Information: This strain was isolated in 1994 in the USA from a patient with duodenal ulcer. This genus consists of organisms that colonize the mucosal layer of the gastrointestinal tract or are found enterohepatically (in the liver). It was only recently discovered (1983) by two Australians (Warren and Marshall) that this organism was associated with peptic ulcers. It is one of the most common chronic infectious organisms, and is found in half the world's population. This organism attacks the gastric epithilial surface, resulting in chronic gastritis, and can cause more severe diseases including those that lead to gastric carcinomas and lymphomas, peptic ulcers, and severe diarrhea. It is an extracellular pathogen that persists in the gastric environment, which has a very low pH, by production of the urease enzyme, which converts urea to ammonia and carbon dioxide, a process which can counteract the acidic environment by production of a base. The toxins include cytolethal distending toxin, vacuolating cytotoxin (VacA) that induces host epithelial cell apopoptosis (cell death), and the cytotoxin associated antigen (CagA) which results in alteration to the host cell signalling pathways. The CagA protein is translocated into host cells by a type IV secretion system encoded by the cag pathogenicity island.