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If the 3573470 bases of Synechocystis PCC 6803 isn't enough for you, the Kazusa DNA Research Institute has more. No, not more Synechocystis genome (nature has her limits), but the same group that completed the first cyanobacterial genome project has embarked on the second: sequencing the genome of the heterocystous cyanobacterium Anabaena (or Nostoc) PCC 7120.
The Anabaena genome holds many secrets unknown to Synechocystis. At 6.42 Mbp, its chromosome is about 80% bigger than that of Synechocystis [Bancroft et al (1989) J Bacteriol 171:5940-5948], never mind about 710 additional kb in large plasmids. Much of the extra coding potential may be accounted for by genes required for nitrogen fixation and the ability to differentiate to heterocysts, cells specialized for protecting the nitrogen fixing apparatus from oxygen. Although this laboratory strain lacks the ability of its close relatives to form hormogonia and akinetes, it is likely that most of the genes required for these two developmental fates remain in the genome.
It isn't as if the Kazusa group hasn't enough on its plate. The group is in the midst of sequencing the first plant genome, that of Arabidopsis. For this reason, progress on the Anabaena project may be relatively slow. Satoshi Tabata, head of the group responsible for both projects, predicted that sequencing the Anabaena genome would require more than a year to complete.