Open Access5-Hydroxymethyluracil in the DNA of a Dinoflagellate
Author(s) -
Peter M. M. Rae
Publication year - 1973
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.70.4.1141
Subject(s) - hyperchromicity , dinoflagellate , guanine , cytosine , dna , thymine , nucleotide , base pair , biology , microbiology and biotechnology , chemistry , biochemistry , gene , botany
During the characterization of DNA from the dinoflagellateGyrodinium cohnii , a large discrepancy was detected between the estimation of guanine + cytosine content from the buoyant density of the DNA in CsCl (56.1% G+C) and from the midpoint (Tm ) of its hyperchromicity induced by a thermal gradient (35.6% G+C). Composition analyses of32 P-labeled nucleotides revealed an actual G+C content of 41.3%, and the presence of an unusual nucleotide amounting to about 37% of the expected thymidylate in unfractionated DNA-a feature that can explain the aberrant behavior of the DNA. The chromatographic properties of the unusual base and UV spectral analyses of the base and its corresponding nucleotide are consistent with its identification as hydroxymethyluracil. This base is not uniformly interspersed with thymine in the DNA. About 10% ofGyrodinium DNA is contributed by a fraction with low hydroxymethyluracil content, which behaves anomalously in Ag+ -Cs2 SO4 density gradients but not in CsCl.