SV40ウイルスDNAを鋳型とするRNAの合成とその分子形態

In vitro synthesis of RNA was carried out with SV40-DNA, mostly form I, as a template by using DNA-dependent RNA polymerise from E. Coli A 19. physicochemical analysis and electron microscopic observation of the synthesized RNA were made to clarify its molecular form andsize, and foliowing results have been obtained. 1. The reaction products of the in vitro RNA synthesis had a broad distribution of sedimentation coefficient covering from 10 S to 28 S with a peak at 16 S determined by sucrose density gradient sedimentation. 2. RNA synthesized in Vero cells infected with SV40 had also a broad distribution of sedimentation coefficient ranging from 10 S to 28 S. 3. Electron microscopy of the in vitro synthesized RNA revealed a single stranded linear structure. Histogram of length distribution of the RNA showed a peak at the molecular length between 1 to 2 μ, corresponding to the molecular weight of 1.08-2.16×10(6) dalton. Small RNA with a molecular length less than 1.0 or 0.3μ and large RNA with a molecular length of 2.0-4.0μ, rarely 4.5 μ, were also observed. 4. The transcription under the present condition was considered to be made along a whole circle of the template DNA measuring 1.5-1.6 μ in the contour length or a part of it such as 2/3-1/2-1/3 of the circle, occationally 2-3 rounds of the circle.