Distribution and orientation of genes in the genome of Pyrococcus OT3

Novel characteristics of genes identified in the genome of a hyper-thermoph ilic archaebacterium, Pyrococcus sp. OT3, are described by correlating the 1.74 M bases in the circular genome to the 12 hours in a clock. From 0:00 t o 7:00 the bases are used to code more for the genes whose transcription ta kes place in the clockwise direction, while from 7:00 to 12:00 to code more for the genes whose transcription takes place in the anti-clockwise direct ion. Genes that are closely related to known eubacterial genes distribute e qually through the genome without showing any strong position-preference. I n contrast, genes that are closely related to known eukaryotic genes have t endency to cluster from 1:30 to 3:30. On the basis of these findings a poss ible link between transcription and-replication and the origin of archaebac terial genomes are discussed.