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)

Wheat embryo ribonucleates. VI. Comparison of the 3′-hydroxyl termini in 'rapidly labelled' RNA from metabolizing wheat embryos with the corresponding termini in ribosomal RNA from differentiating embryos of wheat, barley, corn and pea

1976 ◽  
Vol 54 (3) ◽  
pp. 261-271 ◽  
Author(s):  
K. M. Oakden ◽  
B. G. Lane
Keyword(s):  
18S Rrna ◽  
Short Term ◽  
Plant Materials ◽  
Wheat Embryo ◽  
Pea Seedlings ◽  
Wheat Embryos ◽  
26S Rrna ◽  
Hydroxyl Termini ◽  
End Group

The NaCl-insoluble (2.5 M, 0 °C) fraction of wheat embryo RNA (iRNA) can be labelled when wheat embryos are subjected to either short-term (0.5 h) or long-term (24 h) imbibition in a medium that contains tritium-labelled adenosine, guanosine, cytidine and uridine. Electrophoretic analyses reveal that, after short-term labelling, there is a broadly heterodisperse distribution of radioactivity in 'rapidly labelled' i[3H]RNA, but after long-term labelling, there is an essentially trimodal distribution of radioactivity in i[3H]RNA. End-group analyses reveal that, after short-term labelling, adenosine is the principal 3′-hydroxyl terminus in all centrifugal subfractions of 'rapidly labelled' i[3H]RNA, whereas cytidine (in 5.8S rRNA), guanosine (in 18S rRNA) and uridine (in 26S rRNA) are the principal 3′-hydroxyl termini in centrifugal subfractions of wheat embryo i[3H]RNA. Guanosine is also the principal 3′-hydroxyl terminus in the 18S rRNA of differentiating embryos excized from both monocotyledonous (wheat, barley, corn) and dicotyledonous (pea) seedlings. The implications that the end-group measurements may have for current views about the possible biochemical involvements of 3′-hydroxyl terminal sequences in both mRNA and 18S rRNA are subjects of discussion. Incidental to the principal investigation, an existing technique for analyzing the RNA contents of cellular materials has been appropriately modified to circumvent interference from uv-absorbing pigments, which, when present, prevent application of the method to plant materials.

Wheat-Embryo Ribonucleates. IV. Factors That Influence the Formation and Stability of a Complex Between 5S rRNA and 18S rRNA

1975 ◽  
Vol 53 (3) ◽  
pp. 320-327 ◽  
Author(s):  
A. A. Azad ◽  
B. G. Lane
Keyword(s):  
18S Rrna ◽  
5S Rrna ◽  
23S Rrna ◽  
Wheat Embryo ◽  
Physiological Importance ◽  
5.8S Rrna ◽  
Wheat Embryos ◽  
The Subject ◽  
26S Rrna ◽  
Source Materials

Under the conditions used in this study, wheat-embryo 5S rRNA complexes with its homologous 18S rRNA from wheat embryos and with heterologous 18S rRNA from other eukaryotic source materials such as yeast, L cells, and HeLa cells, but it does not complex with heterologous 16S rRNA from a prokaryote such as Escherichia coli or with homologous or heterologous 26S(23S) rRNA of either eukaryotic or prokaryotic origin.If a solution of wheat-embryo rRNA is simply made 0.3 M with respect to NaCl and then heated at 60 °C for 3 min before quick cooling to room temperature (ca. 20 °C), there is both preferential and efficient complex formation between 5S and 18S rRNA and between 5.8S and 26S rRNA.The laboratory-prepared' complex between wheat-embryo 5S rRNA and its homologous 18S rRNA is more thermostable in 0.1 M NaCl solution than is the 'natural' complex between wheat-embryo 5.8S rRNA and its homologous 26S rRNA, and both complexes 'melt' over a narrow range of temperature.The possible physicochemical and physiological importance of both homologous and heterologous rRNA complexes is the subject of a brief discussion.

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 Identical 3′-terminal octanucleotide sequence in 18S ribosomal ribonucleic acid from different eukaryotes. A proposed role for this sequence in the recognition of terminator codons

1974 ◽  
Vol 141 (3) ◽  
pp. 609-615 ◽  
Author(s):  
John Shine ◽  
Lynn Dalgarno
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Synthesis ◽  
Drosophila Melanogaster ◽  
Ribosomal Rna ◽  
Ribonucleic Acid ◽  
18S Rrna ◽  
Base Sequence ◽  
Terminal Sequence ◽  
Ribosomal Ribonucleic Acid ◽  
Rrna Species

The 3′-terminal sequence of 18S ribosomal RNA from Drosophila melanogaster and Saccharomyces cerevisiae was determined by stepwise degradation from the 3′-terminus and labelling with [3H]isoniazid. The sequence G-A-U-C-A-U-U-AOH was found at the 3′-terminus of both 18S rRNA species. Less extensive data for 18S RNA from a number of other eukaryotes are consistent with the same 3′-terminal sequence, and an identical sequence has previously been reported for the 3′-end of rabbit reticulocyte 18S rRNA (Hunt, 1970). These results suggest that the base sequence in this region is strongly conserved and may be identical in all eukaryotes. As the 3′-terminal hexanucleotide is complementary to eukaryotic terminator codons we discuss the possibility that the 3′-end of 18S rRNA may have a direct base-pairing role in the termination of protein synthesis.

scholarly journals MITOCHONDRIAL RNA FROM CULTURED ANIMAL CELLS

1970 ◽  
Vol 46 (2) ◽  
pp. 245-251 ◽  
Author(s):  
Bland S. Montenecourt ◽  
Margaret E. Langsam ◽  
Donald T. Dubin
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Cell Lines ◽  
Ribosomal Rna ◽  
Gel Electrophoresis ◽  
Base Composition ◽  
Size Class ◽  
Mitochondrial Rna ◽  
Animal Cells ◽  
Molecular Weights

Discrete RNA fractions sedimenting slightly slower than 18s ribosomal RNA have been found in mitochondrial preparations from both hamster (BHK-21) and mouse (L-929) cells. This RNA could be separated into two components, present in approximately equimolar amounts, by prolonged zonal centrifugation or acrylamide gel electrophoresis. The hamster components had sedimentation constants averaging 16.8 and 13.4, and molecular weights (estimated by gel electrophoresis) averaging 0.74 and 0.42 x 106 daltons. Mixed labeling experiments showed that the mouse components sedimented and electrophoresed 3–6% more slowly than the corresponding hamster components. The RNA from both cell lines resembled mitochondrial ribosomal RNA from yeast and Neurospora in being GC poor, and in addition the larger and smaller components resembled each other in base composition. These results, taken with those of other recent studies, are compatible with the idea that our high molecular weight mitochondrial RNA is ribosomal; such RNA would then constitute a uniquely small size-class of ribosomal RNA.

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.

Wheat embryo ribonucleates. X. Metabolism of 3′-hydroxyl termini in the conserved mRNA and tRNA of imbibing wheat embryos

1978 ◽  
Vol 56 (3) ◽  
pp. 197-202 ◽  
Author(s):  
T. D. Kennedy ◽  
B. G. Lane
Keyword(s):  
Ribosomal Rna ◽  
Messenger Rna ◽  
Insoluble Fraction ◽  
Wheat Embryo ◽  
Selective Labelling ◽  
Wheat Embryos ◽  
Chain Lengths ◽  
Hydroxyl Termini ◽  
Terminal Poly ◽  
Mass Component

There are conserved complements of ribosomal RNA (rRNA), transfer RNA (tRNA), and messenger RNA (mRNA) in dry wheat embryos. Although early labelling of RNA is largely directed toward the synthesis of complete molecules of nascent rRNA and mRNA, there is also selective labelling at 3′-hydroxyl termini in conserved polynucleotides when dry wheat embryos are subjected to short-term (0.5 h) imbibition in a medium that contains tritium-labelled adenosine, guanosine, cytidine, and uridine. Conserved tRNA is the principal mass component in NaCl-soluble RNA (sRNA) and most of the 'rapid labelling' of sRNA (rl-sRNA) is a result of labelling at 3′-hydroxyl termini in conserved tRNA. By contrast, although conserved rRNA is the principal mass component in NaCl-insoluble RNA (iRNA), most of the labelled 3′-hydroxyl termini in 'rapidly labelled' iRNA (rl-iRNA) do not appear to derive from rRNA. Although about 10% of the labelled 3′-hydroxyl termini in rl-iRNA originates in conserved poly(A)-rich mRNA, the available evidence leads to the conclusion that most of the labelled 3′-hydroxyl termini in rl-iRNA originates in an unusual NaCl-insoluble fraction of conserved tRNA. During the course of extended imbibition, between 0.5 and 5 h, there are characteristic changes in the chain lengths and labelling patterns for 3′-hydroxyl terminal poly(A) sequences in mRNA. Analytical and physiological implications of these data are subjects of discussion.

Wheat embryo ribonucleates. VII. Rapid, efficient and selective formation of 5S–18S and 5.8S–26S hybrids in an aqueous solution of the four ribosomal polynucleotides, and the results of a search for the corresponding hybrids in wheat embryo ribosomes

1977 ◽  
Vol 55 (1) ◽  
pp. 99-109 ◽  
Author(s):  
K. M. Oakden ◽  
A. A. Azad ◽  
B. G. Lane
Keyword(s):  
Aqueous Solution ◽  
Wheat Germ ◽  
18S Rrna ◽  
Sodium Dodecyl ◽  
Globin Mrna ◽  
Wheat Embryo ◽  
5.8S Rrna ◽  
Free Translation ◽  
26S Rrna ◽  
Selective Formation

(1) If wheat embryo 5S and 5.8S rRNA are differentially labelled, it can be shown that there is highly selective association of 5S [14C]RNA with 18S rRNA, and of 5.8S [3H]RNA with 26S rRNA when a solution (0.3 M NaCl) that contains approximately equimolar amounts of the four ribosomal polynucleotides is heated briefly (3 min) at 60 °C.(2) Comparison of Tm values and melting profiles for laboratory-prepared and natural 5.8S–26S rRNA hybrids suggests that restoration of the natural union between 5.8S and 26S rRNA can be achieved with facility and fidelity in the laboratory.(3) Union between 5.8S and 26S rRNA remains intact when wheat embryo ribosomes are disintegrated either by digestion with pronase or by treatment with sodium dodecyl sulphate, but the same treatments release 5S and 18S rRNA as freely migrating electrophoretic components.(4) Intact 18S and 26S rRNA can be prepared from small and large subunits, respectively, when wheat embryo ribosomes are dissociated by treatment with 0.5 M KCl.(5) Incidental to the principal investigation, it has been shown that, even after storage for more than 6 years at − 70 °C, commercial supplies of roller-milled wheat germ yield S23 extracts that are very active in the cell-free translation of globin mRNA.(6) The physicochemical and possible biochemical significance of various types of intermolecular complexing between pairs of ribosomal polynucleotides is a subject of discussion.

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.

Wheat embryo ribonucleates. VIII. The presence of 7-methylguanosine 'cap structures' in the RNA of imbibing wheat embryos

1977 ◽  
Vol 55 (8) ◽  
pp. 819-824 ◽  
Author(s):  
M. S. Saini ◽  
B. G. Lane
Keyword(s):  
Ribosomal Rna ◽  
Messenger Rna ◽  
Large Fraction ◽  
Deae Cellulose ◽  
Careful Analysis ◽  
Significant Fraction ◽  
Unbound Fraction ◽  
Wheat Embryo ◽  
Wheat Embryos ◽  
The Subject

1. By imbibing wheat embryos in media that contain methyl-labelled methionine, it is possible to label both terminal and nonterminal 7-methylguanosine constituents in NaCl-insoluble (2.5 M, 0 °C) RNA (iRNA).2. Most of the 7-[Me-14C]methylguanosine in wheat embryo i[Me-14C]RNA is present in nonterminal positions of polynucleotide chains, probably in ribosomal RNA.3. By passage through a column of oligo-dT-cellulose, it is possible to show that most of the 7-[Me-3H]methylguanosine in a 'bound' fraction of i[Me-3H]RNA from imbibing wheat embryos is present in terminal 'cap' structures, probably in messenger RNA.4. Although most of the 7-[Me-3H]methylguanosine in the 'unbound' (to oligo-dT-cellulose) fraction of i[Me-3H]RNA was present in nonterminal positions, there was also a highly significant fraction of 7-[Me-3H]methylguanosine in terminal 'cap' structures. Although it will be a subject of continued investigation, possible reasons why a large fraction of the total 7-[Me-3H]-methylguanosine was present in the 'unbound' fraction, in this present study, are a subject of discussion.5. Careful analysis failed to reveal the presence of any N6,O2′-di[Me-3H]methyladenosine in the 'unbound' fraction of i[Me-3H]RNA.6. Factors that might influence the binding of 'cap' oligonucleotides to DEAE-cellulose are the subject of a brief discussion.

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