LIU, W; VLECK, CM; Iowa State Univ.; Iowa State Univ.: Does oxidative damage to DNA increase with age in birds?

Aerobic respiration and exposure to various exogenous agents results in the formation of reactive oxygen species (ROS) that cause oxidative damage to biological systems. Cumulative damage to cellular macromolecules, like DNA, may contribute significantly to aging. Measurement of oxidative lesions in genomic DNA provides an overall estimation of exposure to ROS. Because birds have high rates of metabolism, yet surprisingly long lifespans, they promise to have both lower rate of free radical production and increased capabilities for damage repair. 8-axo-2-deoxyguanosine (8oxodG) is the most commonly used marker and can be measured with relative ease. Oxo8dG levels have been measured in a few avian species, but have not been correlated with ages. We used Zebra Finches (Taeniopygia guttata) of known age from 0.3 to 45 month from our lab colony for this study. An FPG enzyme-gel electrophoresis method was used to determine the 8oxodG levels in DNA extracted from finch pectoral muscle and heart muscle tissues. We observed an agerelated increase in 8oxodG levels in genomic DNA isolated from both muscle and heart tissues, showing that there is a cumulative effects of oxidative damage on DNA over the lifetime of birds. We will measure the 8oxodG level in other tissues. These results may help to explain the relatively greater life span in birds than mammals.