BMC Genomics 2005, 6:136 Additional material Additional File 1 Table S1 Base percentages in the entire mitochondrial genome and in just protein-coding or RNA-coding sections. Figure S1 The pyrimidine-purine walk of each codon position of eight soluble mitochondrial-encoded protein transcripts from Arabidopsis thaliana. Figure S2 The 2-dimensional A- G and T-C walks of human mtDNA-encoded transcripts. Figure S3 Pyri- midine-purine walks of unspliced mitochondrial-encoded transcripts from Arabidopsis thaliana and Marchantia polymorpha. The introns in these transcripts do not encode known proteins. Click here for file [http://www.biomedcentral.com/content/supplementary/1471- 2164-6-136-S1.pdf] Acknowledgements The authors thank the Virginia Bioinformatics Institute for financial support and Harsha Rajasimha for many helpful discussions. References 1. 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