scholarly journals Synthesis and maturation of ribosomal ribonucleic acids in isolated HeLa cell nuclei. A tracer study on the topology of the 45S precursor of ribosomal ribonucleic acids

1974 ◽  
Vol 142 (2) ◽  
pp. 263-272 ◽  
Author(s):  
Asen A. Hadjiolov ◽  
Georgui I. Milchev
Keyword(s):  
Hela Cell ◽  
18S Rrna ◽  
28S Rrna ◽  
Tracer Study ◽  
Cell Nuclei ◽  
Ribonucleic Acids ◽  
Rna Molecules ◽  
Synthesis And Processing ◽  
Main Components ◽  
Low Ionic Strength

The synthesis and processing of RNA by isolated HeLa cell nuclei was studied at low ionic strength in the presence of α-amanitin. The RNA polymerase reaction, with endogenous template and enzyme, rapidly reaches a plateau dependent on the amount of nuclei. Evidence is presented that incorporation of [3H]UMP proceeds only in growing RNA chains, whereas initiation of new RNA chains is arrested. The product formed contains all the main components of the 45S pre-rRNA (precursor of rRNA) maturation pathway (45S, 32S and 20S pre-rRNA; 28S and 18S rRNA). Most of the labelled material is in the mature rRNA components and their immediate precursors, even at very short times of incubation (2min). Small, but definite, 5S and 4S RNA peaks are also observed. At shorter incubation times a substantial amount of [3H]UMP is incorporated into RNA molecules in the 24S and 10–16S zones. This RNA material is considered to represent the non-conserved segments of 45S pre-rRNA in the process of nucleolytic degradation. A model for the tracer study of the topology of 45S pre-rRNA, on arrest of rRNA initiation, is discussed. The experimental evidence obtained supports the following structure of 45S pre-rRNA: 5′-end–28S rRNA unit–18S rRNA unit–nonconserved segment–3′-end.

scholarly journals Differential stability of 28s and 18s rat liver ribosomal ribonucleic acids

1969 ◽  
Vol 115 (1) ◽  
pp. 91-94 ◽  
Author(s):  
P. V. Venkov ◽  
A. A. Hadjiolov
Keyword(s):  
Rat Liver ◽  
Gel Electrophoresis ◽  
18S Rrna ◽  
Heterogeneous Material ◽  
28S Rrna ◽  
Agar Gel ◽  
Ribonucleic Acids ◽  
Different Temperatures ◽  
Rrna Species ◽  
Agar Gel Electrophoresis

Rat liver ribosomal RNA (rRNA) free from nuclease contaminants was isolated by a modification of the phenol technique. The 28s and 18s rRNA species were separated by preparative agar-gel electrophoresis. The two rRNA species were heated at different temperatures under various conditions and the amount of undegraded rRNA was determined by analytical agar-gel electrophoresis. The 18s rRNA remained unaltered after heating for up to 10min. at 90° in water, acetate buffer, pH5·0, or phosphate buffer, pH7·0. Under similar or milder conditions 28s rRNA was partially degraded, giving rise to a well-delimited 6s peak and a heterogeneous material located in the zone between 28s and 6s. The dependence of degradation of 28s rRNA on the temperature and the ionic strength of the medium was studied. The greatest extent of degradation of 28s rRNA was observed on heating at 90° in water. It is suggested that the instability of rat liver 28s rRNA is due to two factors: the presence of hidden breaks in the polymer chain and a higher susceptibility of some phosphodiester bonds to thermal hydrolysis.

scholarly journals Extensive homologies between the methylated nucleotide sequences in several vertebrate ribosomal ribonucleic acids

1978 ◽  
Vol 169 (3) ◽  
pp. 531-542 ◽  
Author(s):  
M S N Khan ◽  
M Salim ◽  
B E H. Maden
Keyword(s):  
Xenopus Laevis ◽  
18S Rrna ◽  
Cultured Cells ◽  
Nucleotide Sequences ◽  
Methyl Groups ◽  
28S Rrna ◽  
Chick Embryo Fibroblast ◽  
Ribonucleic Acids ◽  
Rrna Species ◽  
Complete Digestion

The methylated nucleotide sequences in the rRNA molecules of the following vertebrate cultured cells were compared: human (HeLa); hamster (BHK/C13); mouse (L); chick-embryo fibroblast; Xenopus laevis kidney. In each species the combined 18S, 28S and 5.8S molecules possess approx. 110-115 methyl groups, and the methylated oligonucleotides released after complete digestion of the rRNA by T1 ribonuclease encompass several hundred nucleotides. “Fingerprints” of the three mammalian methyl-labelled 18S rRNA species were qualitatively indistinguishable. “Fingerprints” of digests of 28S rRNA of hamster and mouse L-cells were extremely similar to those of HeLa cells, differing in one and three methylated oligonucleotides respectively. “Fingerprints” of methyl-labelled rRNA from chick and Xenopus strongly resembled those of mammals in most respects, but differed in several oligonucleotides in both 18S and 28S rRNA. At least some of the differences between “fingerprints” appear to be due to single base changes or to the presence or absence of methyl groups at particular points in the primary sequence. The findings strongly suggest that the methylated-nucleotide sequences are at least 95% homologous between the rRNA molecules of the two most distantly related vertebrates compared, man and Xenopus laevis.

Phylogeny of hymenolepidids (Cestoda: Cyclophyllidea) from mammals: sequences of 18S rRNA and COI genes confirm major clades revealed by the 28S rRNA analyses

2021 ◽  
Vol 95 ◽  
Author(s):  
B. Neov ◽  
G.P. Vasileva ◽  
G. Radoslavov ◽  
P. Hristov ◽  
D.T.J. Littlewood ◽  
...  
Keyword(s):  
Ribosomal Rna ◽  
18S Rrna ◽  
Phylogenetic Analyses ◽  
The Other ◽  
Rrna Genes ◽  
Host Switching ◽  
28S Rrna ◽  
Mitochondrial Cytochrome ◽  
Rapid Radiation ◽  
18S Rrna Genes

Abstract The aim of the study is to test a hypothesis for the phylogenetic relationships among mammalian hymenolepidid tapeworms, based on partial (D1–D3) nuclear 28S ribosomal RNA (rRNA) genes, by estimating new molecular phylogenies for the group based on partial mitochondrial cytochrome c oxidase I (COI) and nuclear 18S rRNA genes, as well as a combined analysis using all three genes. New sequences of COI and 18S rRNA genes were obtained for Coronacanthus integrus, C. magnihamatus, C. omissus, C. vassilevi, Ditestolepis diaphana, Lineolepis scutigera, Spasskylepis ovaluteri, Staphylocystis tiara, S. furcata, S. uncinata, Vaucherilepis trichophorus and Neoskrjabinolepis sp. The phylogenetic analyses confirmed the major clades identified by Haukisalmi et al. (Zoologica Scripta 39: 631–641, 2010): Ditestolepis clade, Hymenolepis clade, Rodentolepis clade and Arostrilepis clade. While the Ditestolepis clade is associated with soricids, the structure of the other three clades suggests multiple evolutionary events of host switching between shrews and rodents. Two of the present analyses (18S rRNA and COI genes) show that the basal relationships of the four mammalian clades are branching at the same polytomy with several hymenolepidids from birds (both terrestrial and aquatic). This may indicate a rapid radiation of the group, with multiple events of colonizations of mammalian hosts by avian parasites.

scholarly journals Polyanion-induced release of polyribosomes from HeLa cell nuclei

1975 ◽  
Vol 250 (23) ◽  
pp. 9198-9205
Author(s):  
JA Goidl ◽  
D Canaani ◽  
M Boublik ◽  
H Weissbach ◽  
H Dickerman
Keyword(s):  
Hela Cell ◽  
Cell Nuclei

The Import Pathway of Human and Thermoplasma 20S Proteasomes into HeLa Cell Nuclei Is Different from That of Classical NLS-Bearing Proteins

1999 ◽  
Vol 380 (10) ◽  
Author(s):  
Jutta Mayr ◽  
Huei-Rong Wang ◽  
Petra Nederlof ◽  
Wolfgang Baumeister
Keyword(s):  
Hela Cell ◽  
Cell Nuclei

Whale falls, multiple colonisations of the deep, and the phylogeny of Hesionidae (Annelida)

2015 ◽  
Vol 29 (2) ◽  
pp. 105 ◽  
Author(s):  
Mindi Summers ◽  
Fredrik Pleijel ◽  
Greg W. Rouse
Keyword(s):  
New Species ◽  
Maximum Likelihood ◽  
16S Rrna ◽  
Deep Sea ◽  
Phylogenetic Relationships ◽  
18S Rrna ◽  
Shallow Waters ◽  
28S Rrna ◽  
Mitochondrial Cytochrome ◽  
New Members

Phylogenetic relationships within Hesionidae Grube, 1850 are assessed via maximum parsimony and maximum likelihood analyses of mitochondrial (cytochrome c oxidase subunit I and 16S rRNA) and nuclear (18S rRNA, and 28S rRNA) data. The analyses are based on 42 hesionid species; six of these being new species that are described here. The new species, all from deep (>200 m depth) benthic environments (including whale falls) in the eastern Pacific, are Gyptis shannonae, sp. nov., Neogyptis julii, sp. nov., Sirsoe sirikos, sp. nov., Vrijenhoekia ketea, sp. nov., Vrijenhoekia falenothiras, sp. nov., and Vrijenhoekia ahabi, sp. nov. The molecular divergence among the new members of Vrijenhoekia is pronounced enough to consider them cryptic species, even though we cannot distinguish among them morphologically. Our results also showed that the subfamily Hesioninae Grube, 1850, as traditionally delineated, was paraphyletic. We thus restrict Hesioninae to include only Hesionini Grube, 1850 and refer the remaining members to Psamathinae Pleijel, 1998. The present study increases the number of hesionid species associated with whale falls from one to six and markedly increases the number of described deep-sea hesionid taxa. There appear to have been multiple colonisations of the deep sea from shallow waters by hesionids, though further sampling is warranted.

Three new small nucleolar RNAs that are psoralen cross-linked in vivo to unique regions of pre-rRNA

1993 ◽  
Vol 13 (7) ◽  
pp. 4382-4390
Author(s):  
O J Rimoldi ◽  
B Raghu ◽  
M K Nag ◽  
G L Eliceiri
Keyword(s):  
Small Rnas ◽  
18S Rrna ◽  
Rnase H ◽  
Antisense Oligodeoxynucleotide ◽  
28S Rrna ◽  
Small Nucleolar Rnas ◽  
Rrna Sequence ◽  
Nucleolar Rna ◽  
Nucleolar Rnas

We have recently described three novel human small nucleolar RNA species with unique nucleotide sequences, which were named E1, E2, and E3. The present article describes specific psoralen photocross-linking in whole HeLa cells of E1, E2, and E3 RNAs to nucleolar pre-rRNA. These small RNAs were cross-linked to different sections of pre-rRNA. E1 RNA was cross-linked to two segments of nucleolar pre-rRNA; one was within residues 697 to 1163 of the 5' external transcribed spacer, and the other one was between nucleotides 664 and 1021 of the 18S rRNA sequence. E2 RNA was cross-linked to a region within residues 3282 to 3667 of the 28S rRNA sequence. E3 RNA was cross-linked to a sequence between positions 1021 and 1639 of the 18S rRNA sequence. Primer extension analysis located psoralen adducts in E1, E2, and E3 RNAs that were enriched in high-molecular-weight fractions of nucleolar RNA. Some of these psoralen adducts might be cross-links of E1, E2, and E3 RNAs to large nucleolar RNA. Antisense oligodeoxynucleotide-targeted RNase H digestion of nucleolar extracts revealed accessible segments in these three small RNAs. The accessible regions were within nucleotide positions 106 to 130 of E1 RNA, positions 24 to 48 and 42 to 66 of E2 RNA, and positions 7 to 16 and about 116 to 122 of E3 RNA. Some of the molecules of these small nucleolar RNAs sedimented as if associated with larger structures when both nondenatured RNA and a nucleolar extract were analyzed.

Covalent guanylyl intermediate formed by HeLa cell mRNA capping enzyme

1982 ◽  
Vol 2 (8) ◽  
pp. 993-1001
Author(s):  
D Wang ◽  
Y Furuichi ◽  
A J Shatkin
Keyword(s):  
Sodium Dodecyl Sulfate ◽  
Hela Cell ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Polyacrylamide Gel ◽  
Enzyme Complex ◽  
Cell Nuclei ◽  
Dodecyl Sulfate ◽  
Enzyme Intermediate

Guanylyltransferase, an enzyme that catalyzes formation of mRNA 5'-terminal caps, was isolated from HeLa cell nuclei. The partially purified preparation, after incubation with [alpha-32P]GTP, yielded a single radiolabeled polypeptide by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The guanylylated product was stable at neutral and alkaline pHs and had a pI of 4 by isoelectric focusing. An apparent molecular weight of approximately 68,000 was estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions. The formation of a covalently linked, radiolabeled GMP-protein complex and the associated release of PPi required the presence of [alpha-32P]GTP and divalent cations and incubation between pH 7 and 9. Reaction with [beta-32P]GTP, [alpha-32P]CTP, [alpha-32P]UTP, or [alpha-32P]ATP did not label the approximately 68,000-dalton polypeptide. Phosphoamide linkage of the GMP-enzyme complex was indicated by its sensitivity to cleavage by acidic hydroxylamine or HCl and not by NaOH or alkaline phosphatase. Both formation of the GMP-enzyme intermediate and synthesis of cap structures of type GpppApG from GTP and ppApG were remarkably temperature independent; the rates of enzyme activity at 0 to 4 degrees C were 30% or more of those obtained at 37 degrees C. Radiolabeled GMP-enzyme complex, isolated by heparin-Sepharose chromatography from reaction mixtures, functioned effectively as a GMP donor for cap synthesis with 5'-diphosphorylated oligo- and polynucleotide acceptors. Alternatively, protein-bound GMP could be transferred to PPi to form GTP. The formation of a guanylylated enzyme intermediate appears to be characteristic of viral and cellular guanylyltransferases that modify eucaryotic mRNA 5' termini.

Three-dimensional approaches to the residual structure of histone-depleted HeLa cell nuclei

1984 ◽  
Vol 87 (2) ◽  
pp. 112-123 ◽  
Author(s):  
Dominique Bouvier ◽  
Jean Hubert ◽  
Annie-Pierre Seve ◽  
Michel Bouteille ◽  
Peter B. Moens
Keyword(s):  
Hela Cell ◽  
Three Dimensional ◽  
Cell Nuclei ◽  
Residual Structure
Sign in / Sign up

Export Citation Format

Share Document