The interaction of melanin with ionizing and UVC radiations: Characterization of thymine damage
These studies were undertaken to determine whether melanin could protect DNA against the harmful effects of ionizing or UVC radiations. A simple, in vitro, model system was developed to evaluate eumelanin (Sigma melanin) as a radioprotector of solutions of 0.1 mM thymine or thymidine exposed to 570Gy of ionizing radiation. Sigma melanin was compared to several amino acids, other biomolecules or to other forms of melanin. To investigate the role of melanin as a passive screen of UVC radiation, melanotic (I{sub 3}), amelanotic (AMEL) cells (both derived from a Cloudman S91 melanoma) and non-melanotic (EMT6) cells were labelled with radioactive dTHd and exposed to 0, 1, 5 or 10KJ/m{sup 2} of UVC. The DNA was extracted; the bases hydrolyzed with concentrated HCl. Thymine bases were separated by reverse phase HPLC. No difference in dimer content was observed between I{sub 3} and AMEL cells, but EMT6 cells had nearly twice the amount of dimer. Overall thymine degradation was more pronounced in I{sub 3} cells than in the other two cell lines, due to the production of non-dimer thymine damage. This damage was identified as thymine glycol by HPLC and mass spectrometry. Melanin, upon exposure to UVC, appears to enhance thymine damage by producing oxidative damage.
- Research Organization:
- Rutgers-the State Univ., New Brunswick, NJ (USA)
- OSTI ID:
- 5259608
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DNA
GENETIC RADIATION EFFECTS
MELANIN
RADIOSENSITIVITY EFFECTS
ANIMAL CELLS
IONIZING RADIATIONS
LIQUID COLUMN CHROMATOGRAPHY
MASS SPECTROSCOPY
THYMIDINE
THYMINE
ULTRAVIOLET RADIATION
AZINES
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
CHROMATOGRAPHY
ELECTROMAGNETIC RADIATION
GENETIC EFFECTS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
NUCLEIC ACIDS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PIGMENTS
PYRIMIDINES
RADIATION EFFECTS
RADIATIONS
RIBOSIDES
SEPARATION PROCESSES
SPECTROSCOPY
URACILS
560120* - Radiation Effects on Biochemicals
Cells
& Tissue Culture