A lifetime of retinal light exposure does not appear to increase mitochondrial mutations.
Recently, there have been a number of reports of an accumulation of mutations in the mitochondrial (mt) genome with age. Such mutations may be due in part to the mt oxidative metabolic pathways which provide most of the cell's energy, but also generate free radicals. In addition, the mt genome in some tissues, such as the retina, may also accumulate mutations from the effects of ultraviolet light. To obtain information concerning the possible accumulation of retinal mt mutations with age, we cloned retinal mt DNA from a 71-year-old person. Thirty-two kilobases of sequence from 83 independently isolated clones representing two regions, a coding and a noncoding region, of the mt genome were obtained. Three polymorphisms between these sequences and the standard 'Anderson sequence' were discovered. Only one heteroplasmic mutation was found. These results confirm the low somatic mutation rate found in prior studies utilizing different types of human tissues. In addition, these results suggest that there is little if any accumulated damage to the mt DNA of the retina during normal aging.
Bodenteich
A
A
Laboratory of Biochemical Genetics, National Institute of Mental Health, Washington, DC 20032.
Mitchell
L G
LG
Merril
C R
CR
D000368:Aged; D000375:Aging / Q000235:genetics* / Q000528:radiation effects; D001483:Base Sequence; D015139:Blotting, Southern; D003001:Cloning, Molecular; D004260:DNA Repair / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics*; D003576:Electron Transport Complex IV / Q000235:genetics; D005260:Female; D006801:Humans; D008928:Mitochondria / Q000528:radiation effects*; D008969:Molecular Sequence Data; D009154:Mutation; D009245:NADH Dehydrogenase / Q000235:genetics; D012353:RNA, Transfer, Gly / Q000235:genetics; D012160:Retina / Q000528:radiation effects*; D014466:Ultraviolet Rays / Q000009:adverse effects
D004272:DNA, Mitochondrial; D012353:RNA, Transfer, Gly; D009245:NADH Dehydrogenase; D003576:Electron Transport Complex IV