Macronuclear DNA in <i>Stentor coeruleus</i>: a first approach to its characterization

Abstract

SUMMARY The macronuclei of Stentor coeruleus were isolated on a discontinuous sucrose gradient and their DNA was purified by conventional methods. The GC content was 32 mole%. The DNA banded as a single peak on analytical ultracentrifugation at 1·691 g/cm 3 . The molecular weight of the DNA was 5 × 10 6 to 4 × 10 7 daltons. Genome size determined by DNA–DNA reassociation kinetics was 6 × 10 10 daltons. The macronuclear genome was mostly simple, about 85% being made of non-repetitive sequences.