Deoxyribonucleic acid repair

Smerdon MJ, Lieberman MW (1980) Distribution within chromatin of deoxyribonucleic acid repair synthesis occurring at different times after ultraviolet radiation. Biochemistry 19 2992-3000... 

James MR, Lehmann AR (1982) Role of poly(adenosine diphosphate ribose) in deoxyribonucleic acid repair in human fibroblasts. Biochemistry 21 4007-4013... 

Deoxyribonucleic acid footprinting studies have shown that HMG domains A and B inhibit cleavage by nucleases over a 12- to 15-base-pair region centered around the platinum adduct (81). The HMG proteins can modulate cisplatin cytotoxicity by inhibition of the excinuclease-mediated removal of Pt-d(GpG) adducts from DNA (82). However, this hypothesis has been questioned because there is no evidence for cellular protein shielding of Pt-d(GpG) adducts from repair enzymes (83). 

In animals, there is some evidence that hexachlorobutadiene interacts with genetic material. Male rats administered a single gavage dose of hexachlorobutadiene (20 mg/kg/day) showed a 40% increase in renal deoxyribonucleic acid (DNA) repair and 0.78 alkylations per million nucleotides... 

Ananthaswamy, H.N. Eisenstark, A. (1977) Repair of hydrogen peroxide-induced single-strand breaks va. Escherichia coli deoxyribonucleic acid. J. Bacterial., 130, 187-191... 

Dean, C.J., Feldschreiber, P., Lett, J.T. (1966). Repair of X-ray damage to the deoxyribonucleic acid in Micrococcus radiodurans. Nature (London) 209,49-52. 

Rasmussen, R.E. Painter, R.E. (1964). Evidence for repair of ultra-violet damaged deoxyribonucleic acid in cultured mammalian cells. Nature (London) 203, 1360-1362. 

Deoxyribonucleic acid (DNA) has limited chemical stability. As a result, oxidative damage, hydrolysis, and nonenzymatic DNA methylation occur in vivo at significant rates (L6). Thus, another aspect of this theory is that of intrinsic somatic mutations and the ability of cells to repair the damage to both mitochondrial and nuclear DNA. Indeed, mammalian cells have an elaborate system of DNA repair enzymes which become less efficient with time. Thus, failure to repair damaged DNA or to "misrepair it could lead to gene inactivation or possible excision of... 

H7. Hart, R. W., and Setlow, R. B., Correlation between deoxyribonucleic acid excision-repair and lifespan in a number of mammalian species. Proc. Natl. Acad. Sci. USA 71, 2169-2173 (1974). 

The fidelity of cellular repair and reproduction is determined by a coding system based on polynucleotides - deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). In general (with some inevitable exceptions of course), the information flow is from DNA molecules (genes) which are transcribed to yield RNA molecules which in turn are translated on complex macromolecular protein-RNA assemblies called ribosomes to yield proteins (polymers of amino acids linked by peptide bonds). 

Wavelength, m, or Empirical coefficient Empirical coefficients Empirical coefficients Advanced oxidation process Base excision repair Biochemical Oxygen Demand 5-d Biochemical Oxygen Demand Computational fluid dynamics Chemical oxygen demand Disinfection byproducts Deoxyribonucleic acid Heterotrophic plate count Low-pressure Low-pressure high-output Low-pressure low-output... 

E. Seaman, H. van Vunakis, L. Levine (1972). Serologic estimation of thymine dimers in the deoxyribonucleic acid of bacterial and mammalian cells following irradiation with ultraviolet light and postirradiation repair. J. Biol Chem., 247, 5709-5715. 

Other defense mechanisms are also available. Cells have effective transport systems which pump out foreign chemicals. Our cells are very good at repairing chemically damaged DNA (deoxyribonucleic acid see Chapter 9 for a more detailed discussion of DNA) and even this event is not fatal. Only when the capacity for the cell to repair itself is overwhelmed does disease result. Again, dose is the determining factor. Finally, if all else fails, cells that become carcinogenic often induce an immune response to themselves and are eliminated by this route. When these mechanisms have been exhausted, or, in the case of extreme age, when they have become worn out, disease occurs. 

Some Type-I mutants that do not form capsular polysaccharide lack the dehydrogenase, whereas others lack the epimerase. Such enzyme deficiencies can be repaired by introducing, into cultures of the mutant, deoxyribonucleic acid from pneumococci which possess the enzyme in question. For example, if transforming deoxyribonucleic acid from Type I cells that contain epimerase is added to a culture of mutants which contain dehydrogenase but not epimerase, the mutants become able to form uridine 5-(D-galactop3rranosyluronic acid pyrophosphate). Since such treatment repairs the break in the metabolic sequence described above, the transformed mutants are capable of synthesizing the capsule. 

Richardson, C. C.., R. B. Inman, and A. Kornberg. 1964. Enzymic synthesis of deoxyribonucleic acid. XVIII. The repair of partially single-stranded DNA templates by DNA polymerase. J. Molec. Biol., 9 46-69. 

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