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.

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 The pseudouridine contents of the ribosomal ribonucleic acids of three vertebrate species. Numerical correspondence between pseudouridine residues and 2′-O-methyl groups is not always conserved

1978 ◽  
Vol 171 (3) ◽  
pp. 781-786 ◽  
Author(s):  
D G Hughes ◽  
B E H Maden
Keyword(s):  
Molecular Weight ◽  
Xenopus Laevis ◽  
High Molecular Weight ◽  
Hela Cells ◽  
Numerical Data ◽  
Methyl Groups ◽  
Kidney Cells ◽  
Vertebrate Species ◽  
Ribonucleic Acids ◽  
Rrna Species

The pseudouridine contents of the rRNA species of HeLa cells, mouse L-cells and Xenopus laevis cultured kidney cells were examined. Pseudouridine, like 2′-O-methylation, was found to occur relatively frequently in each of the high-molecular-weight rRNA species. However, the numerical data do not support the idea that there is a general one-to-one relationship between pseudoridine residues and 2′-O-methyl groups in vertebrate rRNA.

An integrative description of Pilatobius nuominensis sp. nov. (Tardigrada: Hypsibiidae) from China

Zootaxa ◽  
2021 ◽  
Vol 5026 (1) ◽  
pp. 65-76
Author(s):  
XUE-LING SUN ◽  
JING-YU ZHANG ◽  
NING WANG ◽  
MIN ZHAO ◽  
XUE-GANG LUO
Keyword(s):  
New Species ◽  
18S Rrna ◽  
Taxonomic Status ◽  
First Record ◽  
Nucleotide Sequences ◽  
28S Rrna ◽  
Dna Fragments ◽  
Caudal Region ◽  
Mitochondrial Coi ◽  
Independent Verification

A newly identified tardigrade species from China, Pilatobius nuominensis sp. nov., belongs to the group of species with cuticle of the dorsal and lateral caudal region with evident irregular polygonal sculpture. Nucleotide sequences of two nuclear (18S rRNA, 28S rRNA) and one mitochondrial (COI) DNA fragments of the new species are provided, which allows an independent verification of the taxonomic status of the new species. This is the first record of the genus Pilatobius in the Great Hinggan Mountains.  

scholarly journals Intranuclear maturation pathways of rat liver ribosomal ribonucleic acids

1976 ◽  
Vol 160 (3) ◽  
pp. 495-503 ◽  
Author(s):  
M D Dabeva ◽  
K P Dudov ◽  
A A Hadjiolov ◽  
I Emanuilov ◽  
B N Todorov
Keyword(s):  
Secondary Structure ◽  
Rat Liver ◽  
Mammalian Cells ◽  
18S Rrna ◽  
Electron Microscopic Observation ◽  
28S Rrna ◽  
Electron Microscopic ◽  
Rrna Species ◽  
A Minor

The maturation of pre-rRNA (precursor to rRNA)in liver nuclei is studied by agar/ureagel electrophoresis, kinetics of labelling in vivo with [14C] orotate and electron-microscopic observation of secondary structure of RNA molecules. (1) Processing starts from primary pre-rRNA molecules with average mol. wt. 4.6×10(6)(45S) containing the segments of both 28S and 18S rRNA. These molecules form a heterogeneous peak on electrophoresis. The 28S rRNA segment is homogeneous in its secondary structure. However, the large transcribed spacer segment (presumably at the 5′-end) is heterogeneous in size and secondary structure. A minor early labelled RNA component with mol.wt. about 5.8×10(6) is reproducibly found, but its role as a pre-rRNA species remains to be determined. (2) The following intermediate pre-rRNA species are identified: 3.25×10(6) mol.wt.(41S), a precursor common to both mature rRNA species; 2.60×10(6)(36S) and 2.15×10(6)(32S) precursors to 28S rRNA; 1.05×10(6) (21S) precursor to 18S rRNA. The pre-rRNA molecules in rat liver are identical in size and secondary structure with those observed in other mammalian cells. These results suggest that the endonuclease-cleavage sites along the pre-rRNA chain are identical in all mammalian cells. (3) Labelling kinetics and the simultaneous existence of both 36S and 21S pre-rRNA reveal that processing of primary pre-rRNA in adult rat liver occurs simultaneously by at least two major pathways: (i) 45S → 41S → 32S+21S → 28S+18S rRNA and (ii) 45S → 41S → 36S+18S → 32S → 28S rRNA. The two pathways differ by the temporal sequence of endonuclease attack along the 41 S pre-rRNA chain. A minor fraction (mol.wt.2.9×10(6), 39S) is identified as most likely originating by a direct split of 28S rRNA from 45S pre-rRNA. These results show that in liver considerable flexibility exists in the order of cleavage of pre-rRNA molecules during processing.

Hypermodified alkali-stable dinucleotide sequences in each of the high-molecular-weight (26S and 18S) ribosomal RNA species of wheat

1977 ◽  
Vol 55 (5) ◽  
pp. 582-586 ◽  
Author(s):  
M. W. Gray ◽  
R. S. Cunningham
Keyword(s):  
Molecular Weight ◽  
Ribosomal Rna ◽  
18S Rrna ◽  
28S Rrna ◽  
Animal Cells ◽  
Wheat Embryo ◽  
Rrna Species ◽  
Wheat Embryos ◽  
The Individual ◽  
26S Rrna

Two hypermodified, alkali-stable dinucleotide sequences, each containing abase modification in addition to sugar methylation, are known to be present in wheat embryo 26S + 18S rRNA (Gray, M. W. (1974) Biochemistry 13, 5453–5463). Quantitative analysis of unfractionated 26S + 18S rRNA had suggested that each of these sequences (Cm-ψp and ψm-Ap, where Cm = O2′-methylcytidine and ψm = O2′-methylpseudouridine) was present in either the 18S or the 26S rRNA species, but not in both, at a frequency of not more than once per chain. In the study reported here, the individual 32P-labeled 18S and 26S rRNA species were isolated from viable wheat embryos germinated in the presence of [32P]orthophosphate. From analyses of phosphodiesterase and alkaline hydrolysates of the separated [32P]RNAs, we conclude that ψm-Ap is confined to wheat cytosol 18S rRNA, whereas Cm-ψp is localized in wheat cytosol 26S rRNA. The presence of ψm in the 18S rRNA of wheat stands in contrast with the situation in animal cells, where this hypermodified nucleoside is located in the 28S rRNA (Khan, M. S. N. &Maden, B. E. H. (1976) J. Mol. Biol. 101, 235–254)

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.

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.

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.

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