In the Early Edition of the Proceedings of the National Academy of Sciences, van Ham and colleagues report the sequencing of the genome of the intracellular symbiont Buchnera aphidicola, from the aphid Baizongia pistacea (BBp) (PNAS, DOI:10.1073/pnas.0235981100, December 30, 2002).

As the bacteria and the host cannot be easily cultured in the laboratory, the Spanish researchers collected insects from the field (from galls of a natural population on Pistacia tree) and then isolated bacterial DNA for whole-genome shotgun sequencing. The BBp genome consists of a 616 kb chromosome and a 2,399 bp plasmid, containing 544 putative genes and nine pseudogenes. van Ham et al. observed extensive intra-population variation and over 1,000 dimorphic SNPs.

Comparison with two other sequenced Buchnera genomes revealed almost perfect chromosomal synteny; 78% of genes are present in all three genomes.