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The frozen tissue was sliced and then homogenized at 20 °C in LiCl, 2 m; lauryltrimethyl ammonium chloride (K & K No. 4484), 5 %; pronase, B grade (Calbiochem), 1 mg/ml and Tris-HCl 10 mM pH 7.5. The homogenate was left to stand 15 min at 20 °C with occasional shaking. After centrifugation at 35 000 × g for 30 min at 0 °C, the supernatant containing the crude DN A was purified by filtration on Ultrogel A 2 (LKB, Sweden). The Ultrogel A 2 column (2.5 × 45 cm) was equilibrated with a solution containing NaCl 2 m, EDTA 2.5 mM, Tris-HCl 10 mM pH 7.5. The flow rate was 3 ml cm−2 h−1. Five ml of the supernatant were placed on the column. The first peak contained highly polymerized (as demonstrated by ultracentrifugation) pure DNA (A260/A230 = 3.19; A260/A280 = 1.82). The yield was 2.26 mg of DNA/g of fresh liver.

Total HMW-RNAs were prepared by three different methods (method with phenol, method with NaCIO4, method without phenol using Ultrogel AcA 22 filtration). Giant RNAs were obtained in the void volume by filtration on Sepharose 2B.The giant RNAs/total HMW-RNA ratio is higher (6.77%) with the gel filtration method than with phenol or NaCIO4 methods (1.41% and 1.00% respectively).The nucleotide composition of these RNAs is DNA-like and the sedimentation constants are approximately 70-100 S.

Total HMW-RNAs were prepared by three different methods (method with phenol, method with NaClO4, method without phenol using Ultrogel AcA 22 filtration). Giant RNAs were obtained in the void volume by filtration on Sepharose 2B. The giant RNAs/total HMW-RNA ratio is higher (6.77%) with the gel filtration method than with phenol or NaClO4 methods (1.41% and 1.00% respectively). The nucleotide composition of these RNAs is DNA-like and the sedimentation constants are approximately 70-100 S.

The frozen tissue was sliced and then homogenized at 20 degree C in LiCl, 2 M; lauryl-trimethyl ammonium chloride (KK No. 4484), 5%; pronase, B grade (calbiochem), 1 mg/ml and Tris-HCl 10 mM pH 7.5. The homogenate was left to stand 15 min at 20 degree C with occasional shaking. After centrifugation at 35 000 X g for 30 min at 0 degree C, the supernatant containing the crude DNA was purified by filtration on Ultrogel A 2 (LKB, Sweden). The Ultrogel A 2 column (2.5 X 45 cm) was equilibrated with a solution containing NaCl 2 M, EDTA 2.5 mM, Tris-HCl 10 mM pH 7.5. The flow rate was 3 ml cm-2 h-1. Five ml of the supernatant were placed on the column. The first peak contained highly polymerized (as demonstrated by ultracentrifugation) pure DNA (A260/A230 = 3.19; A260/A280 = 1.82). The yield was 2.26 mg of DNA/g of fresh liver.