n1_4mer:GRV/n1_4mer:RV = (Global Relative Variance of OU patterns) / (Local Relative Variance of OU patterns)
n0_4mer:D = Distance between local and global OU patterns
n0_4mer:PS = Distance between 2 strands of same DNA molecule
Selected loci indicated by large D, increased GRV associated with decreased RV and moderate increase in PS
NC_011834: Buchnera aphidicola str. Tuc7 (Acyrthosiphon pisum) chromosome,
NCBI: NC_011834
Host Lineage: Buchnera aphidicola; Buchnera; Enterobacteriaceae; Enterobacteriales; Proteobacteria; Bacteria
General Information: This strain is found in the pea aphid, Acyrthosiphon pisum. Buchnera of A. pisum are the prime model of an obligate symbiosis. 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.