Ageing of fixed cytological preparations produces degradation of chromosomal DNA

Abstract
When fixed chromosome preparations were allowed to age for 1–72 h, they became progressively more susceptible to digestion by exonuclease III and by SI nuclease. Analysis of DNA from these aged preparations on agarose gels showed that the molecular weight of the DNA decreased as ageing progressed. We conclude that DNA in fixed chromosome preparations becomes progressively degraded as the preparations age.