The RNA was selectively precipitated by adding NaCl up to 3 M and incubating over-night at 4 ํc RNA was recovered by centrifugation at 8000 x g for 10 min, resuspended in 10 mM Tris-HCL (pH 8.0), 1 mM Na2EDTA and 1% SDS and precipitated at -20 ํแ with sodium acetate and ethanol.