Relation entre l'activité de la desoxyribonuclease acide et la croissance chez le rat

The activity of acid deoxyribonuclease and the mitototic indices have been determined in the Iiver, spleen, kidneys and brain of rats killed 1 hr, 1, 2, 6, 21 and 49 days after birth. The activity of the enzyme expressed per mg DNA, i e. per cell, is lower in the most activevely dividing tissue (spleen). When expressed per mg protein, however, the specific activity of acid DNAase is always highest in the spleen and lowest in the brain, as is also the case for the mitotic indexes in regenerating liver, the activity of acid DNAase is always highest in the spleen and lowest in the brain, as is also the case for the mitotic indexes. In regenerating liver, the activity of acid DNAase markedly increased at the 18th hr post-operation, at a time when no mitosis and no DNA synthesis are observed.
A correlation between acid DNAase activity and rate of growth definitely exists in a homogeneous population of synchronized cells, but is not so unequivocal when one compares different organs exhibiting different rates of growth.