• Arif, Basil M.
  Canadian Forestry Service
  

A nuclear polyhedrosis virus from the spruce budworm, Choristoneura fumiferana, was purified and its genome was extracted by several procedures. Examination of the DNA by methylated albumin kieselguhr chromatography demonstrated that it elutes as a single homogeneous band at 0.75 M NaCl. On CsCl gradients, the genome bands at a density of 1.7075 g/ml. However, analysis on CsCl gradients containing 125µg/ml of ethidium bromide revealed the presence of two fluorescent bands of closed circular (ρ = 1.593 g/ml) DNA molecules. On neutral sucrose gradients the viral DNA was resolved into one component with sedimentation coefficients of 46.25. The molecular weight of the genome was calculated to be 61.0 - 68.3 X 10^6 daltons when analyzed with respect to the DNA of bacteriophage T2. The GC content of the viral genome (48.4%) was computed from the values of two DNA standards from E. coli and Cl. perfringens in heat denaturation experiments in 0.1x SSC.