DNA damage production in CHO cells at elevated temperatures

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Abstract
Induction of DNA lesions in the nucleus of Chinese hamster ovary (CHO) cells was observed at hyperthermic temperatures using the alkaline filter elution and the alkaline sucrose gradient sedimentation methods. These lesions were observed principally at temperatures greater than 45°C with an activation energy of 140 kcal/mole. On alkaline sucrose gradients the cell genome was reduced to a 140 S or 2 × 108 dalton subunit of DNA independent of increasing exposure time at temperatures above 45°C. The large thermal activation energy and the limited DNA size reduction suggest the possible involvement of thermal denaturation of a nuclear polypeptide in the production of these nuclear lesions.
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