Transcription of Tetrahymena mitochondrial DNA in vivo

Electrophoretic strand separation of long DNAs with poly (U,G) in agarose gels

“…Strand separation with ribopolymers in CsCl gradients is time-consuming, expensive and the separations obtained are often strongly dependent on the size and composition of the polymer and the exact experimental conditions [19]. This may explain why we have been unable to reproduce the gradient separation of the complementary strands of Tetrahymena mtDNA (strain ST) reported by Schutgens et al [16], even though this experiment was done five years ago in the same lab with the same batch of poly(U,G). In contrast, our gel procedure for strand separation has been highly reproducible.…”

“…The hybridization of both bands with 21S rRNA is in full agreement with our previous finding that the 21S rRNA cistron lies within the duplication-inversion of this mtDNA. In a previous paper from this laboratory Schutgens et al [16] reported that total Tetrahymena mitochondrial rRNA hybridized with only one of the complementary strands of Tetrahymena mtDNA. This is incompatible with the known arrangement of rRNA genes on this DNA and the results in Fig.…”

The binding of poly(rA) and poly(rU) to denatured DNA.I. Model studies with homopolymers.

“…1.620 [16] infer from the graphs presented in Figs 6 and 8 that the complex between poly(rA) and (dT)n tracts is only stable for n l13, whereas the complex between poly(rU) and (dA)n tracts is already stable for n),4 in 6.6 M CsCl at 220C. Since (dT) tracts larger n than 13 residues are not likely to occur on a large scale in the DNAs tested for poly(rU) binding [1][2][3][4][5][6][7][8][9][10], a poly(rA)-induced density shift after a suitable pre-annealing step might be below the resolution of the gradient. Third, the density of poly(rA) in CsCl is much lower than that of poly(rU) and the density of the poly(rA).2poly(dT) complex is much lower than that of the 2poly(rU).poly(dA) complex (Table I).…”

“…Binding of polyribonucleotides to single-stranded DNA in concentrated CsCl provides a convenient method to separate the complementary strands of many DNAs [1][2][3][4][5][6][7][8][9][10], because more of the polyribonucleotide is bound to one strand than to the other. Interest in the mechanism of polyribonucleotide binding was raised by the finding that binding often correlates with transcriptional specificity [11][12][13][14].…”

Uniqueness of Sperm mtDNA as Compared to Somatic mtDNA in Ram

“…1974. Mitochondria have the capability to transcribe this D N A into rRNA (Wu et al 1972;Schutgens et al 1973), tRNA (Nass & Buck 1970;Casey et al 1974a,b) and into messenger-type RNA components (Ojala 8c Attardi 1974;Hirsch & Penman 1973 and translate this RNA into proteins (Ashwell & Work 1970).…”