title: Error-reducing structure of the genetic code indicates code origin in non-thermophile organisms.
abstract: During the RNA World, organisms experienced high rates of genetic errors, which implies that there was strong evolutionary pressure to reduce the errors' phenotypical impact by suitably structuring the still-evolving genetic code. Therefore, the relative rates of the various types of genetic errors should have left characteristic imprints in the structure of the genetic code. Here, we show that, therefore, it is possible to some extent to reconstruct those error rates, as well as the nucleotide frequencies, for the time when the code was fixed. We find evidence indicating that the frequencies of G and C in the genome were not elevated. Since, for thermodynamic reasons, RNA in thermophiles tends to possess elevated G+C content, this result indicates that the fixation of the genetic code occurred in organisms which were either not thermophiles or that the code's fixation occurred after the rise of DNA.
authors.affiliation: Center for Applied Mathematics, Cornell University, Ithaca, New York 14853, USA. gfriend@cam.cornell.edu
authors.forename: Alexander
authors.initials: A
authors.lastname: Gutfraind
authors.forename: Achim
authors.initials: A
authors.lastname: Kempf
mesh_terms: D001482:Base Composition; D004247:DNA / Q000737:chemistry / Q000235:genetics; D019143:Evolution, Molecular; D005815:Genetic Code; D006358:Hot Temperature; D000069497:Origin of Life; D012313:RNA / Q000737:chemistry* / Q000235:genetics
chemical_list: D012313:RNA; D004247:DNA