The Kinetic Complexity of <i>Paramecium</i> Macronuclear Deoxyribonucleic Acid

Abstract

SYNOPSIS DNA extracted from macronuclei of axenically cultured Paramecium aurelia has been characterized with regard to its kinetic complexity. Renaturation of macronuclear DNA from this protozoon appeared to follow 2nd order kinetics and revealed the presence of 2 components: a main component comprising ∼96% of the genome which renatured slowly and a minor component comprising ∼4% of the genome which renatured at a rate ∼3000 faster than the main component. The value of the kinetic complexity of the main component has been estimated at 3.8 × 10 10 daltons and that of the minor component at 1.45 × 10 7 daltons. It is suggested that the macronucleus contains ∼840 diploid copies of the slowly renaturing component; for each copy of the latter there are ∼100 copies of the fast renaturing component.