A rapid high-yield isolation method for nuclear envelope ghosts

A method is presented for the isolation of nuclear envelopes from isolated Tetrahymena macronuclei. In principle, nuclei are treated with DNase and RNase at low Ca²⁺/Mg²⁺ concentration followed by an extraction with 1 NaCl. The major advantages of this method are: (1) Unfragmented nuclear envelopes are obtained in the form of ghosts consisting of two juxtaposing nuclear membranes interrupted by pores as revealed by thin-section and freeze-etch electron microscopy. (2) The ghosts are obtained in high yield (60%) within a short period (1 h). (3) The nuclear envelopes largely retain their lipid composition. An average ghost contains about 96% of total phospholipids of an average nucleus. Nuclei and ghosts reveal an almost identical pattern of phospholipids and fatty acids as shown by thin-layer and gas-chromatography. (4) The lipids in the ghosts largely remain arranged in bilayers as probed by electron spin resonance using 5-doxylstearic acid as a spin label.