A Marker for Mammalian DNA Sedimentation

Authors:
  • KWK. T. Wheeler
    K. T. Wheeler
  • JDJ. DeWitt
    J. DeWitt
  • JLJ. T. Lett
    J. T. Lett
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Abstract
DNA from Chinese hamster ovary (CHO) cells which had been irradiated with 1 krad of x-rays was sedimented in alkaline sucrose gradients with the single strands of DNA and and large DNA-containing species which can be released from mammalian cells. We have found that the CHO DNA profile is suited for use as a marker in such circumstances because it has both a characteristic shape and principal component (∼165S) which are substantially independent of DNA concentration, EDTA concentration, and lytic storage time. The sedimentation rate of the principal component varied with rotor speed and radius as predicted by Zimm for single-stranded DNA molecules with a molecular weight of approximately 5× 108 daltons. The irradiated CHO cells can be frozen and stored without changing the sedimentation characteristics of the marker DNA.