Genome context analyses of the origins in the oriCa and oriCb families. A. Phylogenetic tree based on the 16S rRNA genes (Methanocaldococcus jannaschii was added as an outgroup) and the distribution of the oriCa and oriCb families in the haloarchaeal genomes. + indicates the presence of this family of origins in the chromosome, and (+) indicates its presence in an extrachromosomal element. B and C. The regions around oriCa (B) and oriCb (C). Shaded regions denote similarity greater than 70% by BLASTN analyses. The orc/cdc6 genes are highlighted in red; genes annotated with transposase (tnp) are highlighted in purple; rRNAs, including 16S rRNA, 23S rRNA and 5S rRNA, are highlighted in yellow; tRNAs are highlighted in green, with T, C and A representing the Thr-tRNA, Cys-tRNA and Ala-tRNA genes, respectively. oriCb origins of replication in H. volcanii, H. borinquense and H. lacusprofundi are indicated by teal rectangles.