DNA FROM 2 ORGYIA-PSEUDOTSUGATA BACULOVIRUSES - MOLECULAR-WEIGHT DETERMINATION BY MEANS OF ELECTRON-MICROSCOPY AND RESTRICTION ENDONUCLEASE ANALYSIS

Both aqueous and urea-formamide procedures for spreading nucleic acid were employed for electron microscopic studies on the DNAs from the nucleopolyhedrosis bundle virus (NPBV) and the nucleopolyhedrosis single-rod virus (NPSV) both of which are pathogenic for Orgyia pseudotsugata. The molecular weight estimates via electron microscopy were derived by comparison of the mean length values for the double-stranded relaxed circular DNAs with that of SV40 DNA. The aqueous and urea-formamide spreading methods yielded NPSV DNA molecular weight values of 103 × 106 and 104 × 106 daltons, respectively, and molecular weight values of 87 × 106 and 85 × 106 daltons for NPBV DNA. These molecular weights were compared with molecular weight estimates from restriction endonuclease analysis, sedimentation analysis, and renaturation kinetic analysis. DNA located within the NPBV polyhedra but external to virions was characterized by restriction endonuclease analysis and examined by electron microscopy. It was determined to be composed of fragments of random size and to be viral origin. © 1979.