DNA modification in chick heart and cerebrum.
Heart muscle cells and cerebral neurons are known to lose the ability to proliferate and are called terminally differentiated cells. They are generated in appropriate numbers during embryogenesis and retained throughout adult life without turnover. We are interested in such a long-lived DNA. We isolated DNA from chick heart and cerebrum and compared it with DNA from other organs after incubation with DNase I. Single-strand breaks were assessed using a reaction system composed of DNA and Escherichia coli DNA polymerase. The DNA of both organs was relatively resistant to DNase I, and DNA modification occurred during embryogenesis. CIMS (chemical ionization mass spectrometry) indicated that the molecular mass of the deoxynucleoside of both DNAs was larger than that of the corresponding canonical deoxyribonucleoside by m/z 28 (or 30 for the protonated form). The difference between these deoxynucleosides is based on a difference in sugar constituents. Cerebral deoxynucleotides were analyzed by (13)C NMR. An extra signal near 173 ppm was observed, which was assigned to the amide carbonyl. We propose a model of the deoxynucleoside where a carbonyl residue exists between the base and the 2-deoxyribose moiety of the canonical deoxyribonucleoside.
Department of Biological Responses, Institute for Virus Research, Kyoto University, Shogoin-kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. kkagawa@virus.kyoto-u.ac.jp
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D000818:Animals; D002236:Carbohydrate Conformation; D002467:Cell Nucleus / Q000378:metabolism; D002645:Chickens; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000737:chemistry*; D004256:DNA Polymerase I / Q000737:chemistry; D003850:Deoxyribonuclease I / Q000737:chemistry; D003853:Deoxyribonucleosides / Q000032:analysis; D003854:Deoxyribonucleotides / Q000032:analysis; D004926:Escherichia coli / Q000201:enzymology; D066298:In Vitro Techniques; D007659:Ketones / Q000032:analysis; D013058:Mass Spectrometry; D009206:Myocardium / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D009928:Organ Specificity; D012680:Sensitivity and Specificity; D013687:Telencephalon / Q000737:chemistry*; D013997:Time Factors
D003853:Deoxyribonucleosides; D003854:Deoxyribonucleotides; D007659:Ketones; D004247:DNA; D004256:DNA Polymerase I; D003850:Deoxyribonuclease I