Query: NC_006831:622906 Ehrlichia ruminantium str. Gardel, complete genome
Lineage: Ehrlichia ruminantium; Ehrlichia; Anaplasmataceae; Rickettsiales; Proteobacteria; Bacteria
General Information: This strain was isolated from the Caribbean island of Guadeloupe. Obligate intracellular bacterium and causative agent of heartwater. This organism causes heartwater, a disease with a high mortality rate that affects both wild and domesticated ruminants in sub-Saharan Africa and parts of the Caribbean. The name heartwater refers to the hydropericardium (excessive fluid in the sac surrounding the heart) commonly found associated with infection. This organism is found in membrane-bound vacuoles in endothelial cells and neutrophils and is an obligate intracellular parasite.
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.