Transcription of rat DNA fractions reassociated to various cOt values.

Two fractions of rat liver DNA: "intermediate" (reassociated to COt = 1 - 10(2), moleXsecX1(-1)) and "slow" (COt = 10(2) - 10(5) showed differences in template activity on transcription with E. coli RNA-polymerase. The "intermediate" fraction both in double- and single-stranded form was a better template than the "slow" one. The efficiency of transcription dropped progressively for the template obtained at COt values increasing from 10(2) to 10(6). No differences in the template activity of the "intermediate" and "slow" fractions were observed when rifampicin-resistant transcription was studied.