Chromosomal location of ribosomal RNA cistrons in Escherichia coli

Summary DNA isolated from a strain carrying an episomal that contains the str spc region (60–66 min) hybridized with significantly more ribosomal RNA than did DNA from either the parental strain that does not carry the episome or from a similar strain carrying an episome covering a neighboring region (55–61 min) of the genome.     

Physical linkage of the 5 S cistrons to the 18 S and 28 S ribosomal RNA cistrons in Saccharomyces cerevisiae

In the yeast Saccharomyces cerevisiae, there are approximately 150 cistrons coding for 5 S RNA. These cistrons are interspersed with the cistrons coding for the high molecular weight ribosomal RNAs.     

Transcription termination and RNA processing in the 3''-end spacer of mouse ribosomal RNA genes.

The 3' termini of ribosomal RNA precursors from mouse FM3A cultured cells are mapped to eight sites within 625 bp downstream from the 3' terminus of 28 S rRNA. Three additional sites are mapped in liver RNA from C3H/He strain mice. Two of them, the sites at 570 bp and 625 bp are assumed to be termination sites in vivo, because they correspond to in vitro termination sites of RNA polymerase I, and 45 S RNAs having these 3' termini decay with kinetics distinct from others. The amount of 45 S RNA having the 3' terminus at other sites is variable among several mouse strains, despite their having the same DNA sequence in these regions. The ability to produce 3' termini in these sites seems to follow Mendel's law of inheritance. Therefore, we postulate that these nine sites are RNA processing sites which are controlled genetically.     

The number, physical organization and transcription of ribosomal RNA cistrons in an archaebacterium: Halobacterium halobium.

Because it is now clear that archaebacteria may be as distinct from eubacteria as either group is from eukaryotic cells, and because a specifically archaebacterial ancestry has been proposed for the nuclear-cytoplasmic component of eukaryotic cells, we undertook to characterize, for the first time, the ribosomal RNA cistrons of an archaebacterium (Halobacterium halobium). We found these cistrons to be physically linked in the order 16S-23S-5S, and obtained evidence that they are also transcribed from a common promoter(s) in the order 5'-16S-23S-5S-3'. We showed that, although slightly larger immediate precursors of 16S and 23S are readily seen, no common precursor of both 16S and 23S can be easily detected in vivo. In all these respects the archaebacterium H. halobium is like a eubacterium and unlike the nuclear-cytoplasmic component of eukaryotic cells. We found, however, that it differs from eubacteria of comparable (large) genome size in having only one copy of the rRNA gene cluster per genome.