Evidence that 32 S nRNA contains 5.8 S rRNA was provided by studies on specific oligonucleotide sequences of these RNA species. Purified 32P-labeled 5.8 and 28 S rRNA and 32 S RNA were digested with T-1 ribonuclease, and the products were fractionated according to chain length by chromatography on DEAE-Sephadex A-25 at neutral pH. The oligonucleotides in Peak 8 were treated with alkaline phosph...

Genetic manipulations have revealed the functions of RNA helicases in ribosomal RNA (rRNA) biogenesis in yeast. However, no report shows the role of an RNA helicase in rRNA formation in higher eukaryotes. This study reports the functional characterization of the frog homologue of nucleolar RNA helicase II/Gu (xGu or DDX21). Down-regulation of xGu in Xenopus laevis oocyte using an antisense olig...

The regulation of ribosome formation in eukaryotic cells still remains an intractable problem despite the extensive knowledge available concerning the details of the nucleolar synthesis and processing of the rRNA. Within the nucleolus, which is the site of ribosome formation (2, 15, 20), a 45 S precursor is methylated and combined with ribosomal proteins during transcription (33); the 45 S prec...

The regulation of ribosome formation in eukaryotic cells still remains an intractable problem despite the extensive knowledge available concerning the details of the nucleolar synthesis and processing of the rRNA. Within the nucleolus, which is the site of ribosome formation (2, 15, 20), a 45 S precursor is methylated and combined with ribosomal proteins during transcription (33); the 45 S prec...

A method is described for the isolation of pulse-labelled RNA from nuclei and subnuclear fractions of Physarum polycephalum. At all times during interphase the nucleolar RNA consisted mainly of a 34-S rRNA precursor with only small amounts of 26-S and 19-S rRNAs. The nucleoplasmic RNA consisted of predominantly mature 26-S rRNA with small amounts of 19-S rRNA and a 30-S RNA species. The 30-S RN...

The pseudouridylation of ribosomal RNA of Saccharomyces carlsbergensis was investigated with respect to its timing during the maturation of rRNA and its sequence specificity. Analysis of 37-S RNA, the common precursor to 17-S, 5.8-S and 26-S rRNA and most probably the primary ribosomal transcript, shows that this RNA molecule contains already most if not all of the 36-37 pseudouridine residues ...