Query: NC_014816:545441 Asticcacaulis excentricus CB 48 chromosome 1, complete sequence
Lineage: Asticcacaulis excentricus; Asticcacaulis; Caulobacteraceae; Caulobacterales; Proteobacteria; Bacteria
General Information: Environment: Fresh water; Isolation: Pondwater; Temp: Mesophile; Isolation: pond water. Asticcacaulis excentricus inhabits aquatic environments and plays an important part in biogeochemical cycling of organic nutrients. This bacterium undergoes an unusual developmental cycle in which a swarming motile cell becomes a stalked cell that is attached to a solid surface. The stalked cell then undergoes asymmetric cell division and produces one flagellated motile daughter cell and one stalked daughter cell. Thus, the asymmetric processes in this organism provide useful models for differentiation and development.
Subject: NC_004061:498483 Buchnera aphidicola str. Sg (Schizaphis graminum), complete genome
Lineage: Buchnera aphidicola; Buchnera; Enterobacteriaceae; Enterobacteriales; Proteobacteria; Bacteria
General Information: This strain is the symbiont of the aphid Schizaphis graminum and contains a large circular chromosome. Aphid endosymbiont. Almost all aphids contain maternally transmitted bacteriocyte cells, which themselves contain bacteria called Buchnera. The aphids live on a restricted diet (plant sap), rich in carbohydrates, but poor in nitrogenous or other essential compounds. It is believed that the Buchnera provide the essential nutrients the host lacks. Besides a nutritional co-dependence, due to a co-existence of millions of years, Buchnera have lost the ability to produce cell surface components such as lipopolysaccharides. This makes for an obligate endosymbiont relationship between host and Buchnera. Buchnera are prokaryotic cells which belong to the gamma-Proteobacteria, closely related to the Enterobacteriaceae family. Phylogenetic studies using 16S rRNA indicate that the symbiotic relationship was established around 200-250 million years ago. Since Buchnera are closely related to Escherichia coli and Haemophilus influenzae, comparative genomic studies can shed light on the evolutionary mechanisms of intracellular endosymbiosis as well as the different underlying molecular basis between organisms with parasitic behavior and symbionts.