Nuclear components of dividing cells

Abstract

Ultra-violet microspectrography has been employed to determine the total quantity of absorbing substances in living cell nuclei. The values obtained by this method for non-dividing cells such as erythrocytes and sperm heads agree with those obtained by biochemical extraction methods. However, a range of values of from twice to four times that of the homologous diploid non-dividing nucleus (erythrocytes) is found in tissue culture interphase nuclei. A film technique has demonstrated that this tissue culture range of values is correlated with the time since the previous mitosis. The absorbing material doubles during interphase, and it has been shown that there is no sudden increase in absorbing material during prophase. Further, photometric measurements show that there is the same amount of Feulgen staining material in the recently divided tissue-culture nucleus as in the erythrocyte. The Feulgen staining component also increases during interphase. It is concluded that desoxyribose nucleic acid is synthesized during interphase, and that the additional absorbing molecules may include DNA precursors.