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Longevity-dependent organ-specific accumulation of DNA damage in two closely related murine species
Abstract:
To measure directly the accumulation of DNA damage with age, and to understand better the effect of modulators of DNA damage in vivo, the DNA of brain, liver, and kidney of two mice from different families, Mus musculus and Peromyscus leucopus, have been examined for age-dependent accumulation of single-strand breaks plus alkali-labile bonds, by the alkaline sucrose sedimentation method. These two species of small rodents are closely related taxonomically, yet differ significantly in maximum achievable lifespan. Using the reciprocal of the number average molecular weight for estimation of DNA size, these analyses indicate that: (a) DNA damage does not measurably accumulate in brain tissue; (b) the accumulation of DNA damage was more pronounced in hepatic DNA than other tissue DNA; and (c) the rate of accumulation of DNA damage in liver and kidney cells with age was greater in the shorter-lived species (M. musculus) and was inversely proportional to maximum achievable lifespan. There are suggestions that a similar threshold might exist for tolerance of DNA damage in the two species in specific organs, and that these species differ in the rate at which this threshold is reached as a function of maximum achievable lifespan.
Insights
DNA damage accumulation varies by tissue and species. Shorter-lived mice showed faster DNA damage in liver and kidney, suggesting a link between DNA repair and lifespan.
Area of Science:
- Genetics
- Aging Research
- Molecular Biology
Background:
- Aging is associated with increased DNA damage.
- Understanding DNA damage accumulation is crucial for aging research.
- Rodent models offer insights into lifespan differences.
Purpose of the Study:
- To directly measure age-dependent DNA damage accumulation in different tissues.
- To investigate the influence of lifespan on DNA damage rates.
- To compare DNA damage accumulation in two closely related rodent species with different lifespans.
Main Methods:
- Alkaline sucrose sedimentation method used to analyze DNA from brain, liver, and kidney.
- Examined DNA single-strand breaks and alkali-labile bonds in Mus musculus and Peromyscus leucopus.
- Estimated DNA size using the reciprocal of number average molecular weight.
Main Results:
- No significant DNA damage accumulation observed in brain tissue with age.
- Hepatic DNA showed more pronounced accumulation of DNA damage compared to other tissues.
- Faster DNA damage accumulation in liver and kidney of shorter-lived Mus musculus, inversely proportional to lifespan.
Conclusions:
- DNA damage accumulation is tissue-specific and influenced by species-specific lifespan.
- The rate of DNA damage accumulation correlates inversely with maximum achievable lifespan.
- Potential conserved thresholds for DNA damage tolerance may exist across species.