Query: NC_016931:171444 Rickettsia massiliae str. AZT80 chromosome, complete genome
Lineage: Rickettsia massiliae; Rickettsia; Rickettsiaceae; Rickettsiales; Proteobacteria; Bacteria
General Information: Members of this genus, like other Rickettsial organisms such as Neorickettsia and Anaplasma, are obligate intracellular pathogens. In both groups, the bacteria are transmitted via an insect, usually a tick, to a host organism where they target endothelial cells and sometimes macrophages. They attach via an adhesin, rickettsial outer membrane protein A, and are internalized where they persist as cytoplasmically free organisms. This bacterium is a member of the spotted fever group of the Rickettsiales and has been isolated from ticks in Europe and Africa. Rickettsia massiliae does not appear to cause disease in humans.
Subject: NC_010628:6165632 Nostoc punctiforme PCC 73102, complete genome
Lineage: Nostoc punctiforme; Nostoc; Nostocaceae; Nostocales; Cyanobacteria; Bacteria
General Information: The strain was isolated from a symbiotic association with the gymnosperm cycad Macrozamia sp. It typically grows in freshwater habitats. This genera of cyanobacteria are typically terrestrially-associated and are especially found in limestone or nutrient-poor soils. They are very similar to Anabaena spp. and historically they have been distinguished on the basis of morphological and life cycle characteristics. Nostoc spp. can grow heterotrophically or photoheterotrophically, and form heterocysts for nitrogen fixation. This organism can form nitrogen-fixing symbiotic relationships with plants and fungi such as the bryophyte Anthoceros punctatus. The relationship is relatively simple as compared to the Rhizobial symbiotic relationship. In the presence of the plant, hormogonia (short motile filaments) infect the plant, and then form long heterocyst-containing (nitrogen-fixing differentiated bacterial cells) filaments. The bacterial cell receives carbon sources in exchange for fixed nitrogen.