DEGRADATION OF DNA IN DRIED TISSUES BY ATMOSPHERIC OXYGEN

Recently, DNA of extinct creatures have been brought into analyses. Th e difficulty in this field of research is DNA degradation. Oxidative d amage is considered to be one of the causes of the DNA degradation. We studied how DNA in dried tissue was affected by atmospheric oxygen us ing freeze-dried rat liver as a model. In tissues exposed to oxygen, D NA degradation occurred within several months and the amount of 8-hydr oxy-2'-deoxyguanosine in DNA rapidly increased. The DNA degradation wa s inhibited by lipid extraction prior to the exposure to atmospheric o xygen. Purified lambda phage DNA was not affected by oxygen. Cellular DNA and RNA were degraded slowly in nitrogen air. These results sugges t that both atmospheric and endogenous oxygens play a role in DNA degr adation in dried tissues. (C) 1995 Academic Press, Inc.