Showing papers on "RNA published in 1969"
TL;DR: Direct support for the idea that regulation of gene activity underlies cell differentiation comes from evidence that much of the genome in higher cell types is inactive and that different ribonucleic acids are synthesized in different cell types.
Abstract: Cell differentiation is based almost certainly on the regulation of gene activity, so that for each state of differentiation a certain set of genes is active in transcription and other genes are inactive. The establishment of this concept (1) has depended on evidence
indicating that the cells of an organism generally contain identical genomes (2). Direct support for the idea that regulation of gene activity underlies cell differentiation
comes from evidence that much of the genome in higher cell
types is inactive (3) and that different ribonucleic acids (RNA) are synthesized in different cell types (4).
1,898 citations
TL;DR: A technique is described for forming molecular hybrids between RNA in solution and the DNA of intact cytological preparations and a low level of gene amplification was also detected in premeiotic nuclei (oogonia) of the toad Xenopus.
Abstract: A technique is described for forming molecular hybrids between RNA in solution and the DNA of intact cytological preparations. Cells in a conventional tissue squash are immobilized under a thin layer of agar. Next they are treated with alkali to denature the DNA and then incubated with tritium-labeled RNA. The hybrids are detected by autoradiography. The technique is illustrated by the hybridization of ribosomal RNA to the amplified ribosomal genes in oocytes of the toad Xenopus. A low level of gene amplification was also detected in premeiotic nuclei (oogonia).
1,171 citations
TL;DR: The presence of extrachromosomal nucleoli in amphibian oocytes has permitted isolation and electron microscopic observation of the genes coding for ribosomal RNA precursor molecules.
Abstract: The presence of extrachromosomal nucleoli in amphibian oocytes has permitted isolation and electron microscopic observation of the genes coding for ribosomal RNA precursor molecules. Visualization of these genes is possible because many precursor molecules are simultaneously synthesized on each gene. Individual genes are separated by stretches of DNA that apparently are not transcribed at the time of synthesis of precursor rRNA in the extrachromosomal nucleoli.
812 citations
TL;DR: An understanding of how normal cells and normal animals prevent expression of endogenous viral information would appear to offer one of the best hopes for the control of naturally occurring cancers.
Abstract: Evidence from sero-epidemiological studies and from cell culture studies supports the hypothesis that the cells of many, and perhaps all, vertebrates contain information for producing C-type RNA viruses. It is postulated that the viral information (the virogene), including that portion responsible for transforming a normal cell into a tumor cell (the oncogene), is most commonly transmitted from animal to progeny animal and from cell to progeny cell in a covert form. Carcinogens, irradiation, and the normal aging process all favor the partial or complete activation of these genes. An understanding of how normal cells and normal animals prevent expression of endogenous viral information would appear to offer one of the best hopes for the control of naturally occurring cancers.
799 citations
TL;DR: A new protein has been isolated from E. coli which causes specific termination and release of RNA during synthesis in vitro and has been given the name ρ-factor.
Abstract: A new protein has been isolated from E. coli which causes specific termination and release of RNA during synthesis in vitro. It has been given the name ρ-factor.
739 citations
TL;DR: It is concluded that the method provides a satisfactory measurement of molecular weight, which is almost independent of the nucleotide composition of RNA at moderate salt concentrations.
Abstract: 1. The effects of changes in experimental conditions on the mobility of RNA in polyacrylamide-gel electrophoresis were investigated. 2. The linear relation between log(molecular weight) and electrophoretic mobility was shown to be independent within limits of salt or gel concentration. 3. The relative mobility of RNA with low content of guanylic acid and cytidylic acid residues was decreased in low-ionic-strength buffer. This was related to a small relative decrease in sedimentation coefficient. 4. However, Mg2+ ion caused almost no increase in mobility although it was associated with large increases in sedimentation coefficient. This suggested opposing actions of Mg2+ ion on the size and effective charge of the RNA. 5. It is concluded that the method provides a satisfactory measurement of molecular weight, which is almost independent of the nucleotide composition of RNA at moderate salt concentrations.
699 citations
TL;DR: Autoradiography has revealed in a stringent strain of E. coli two compounds that seem to be involved in the inhibition of the synthesis of RNA.
Abstract: Autoradiography has revealed in a stringent strain of E. coli two compounds that seem to be involved in the inhibition of the synthesis of RNA.
690 citations
TL;DR: Radioactive RNA introduced into “target” cells can be induced to form hybrids with nuclear DNA and the location of these hybrids can be detected by autoradiography.
Abstract: Radioactive RNA introduced into “target” cells can be induced to form hybrids with nuclear DNA. The location of these hybrids can be detected by autoradiography.
619 citations
TL;DR: The initiator regions of the three cistrons of R17 bacteriophage RNA have been isolated and sequenced and contain a UGA triplet as well as the expected AUG and two contain the sequence GGUUUGA.
Abstract: The initiator regions of the three cistrons of R17 bacteriophage RNA have been isolated and sequenced. All three regions contain a UGA triplet as well as the expected AUG and two contain the sequence GGUUUGA. The initiator regions thus represent untranslated sequences between termination and initiation codons.
595 citations
TL;DR: Comparison of properties of the system regulating the synthesis of these compounds with those of the amino acid control of RNA biosynthesis suggests that the unusual compounds participate in an early step in the mechanism which leads to the slowing ofRNA biosynthesis during amino acid starvation of stringent strains.
443 citations
TL;DR: Bacterial polyribosomes, ribosomes and ribosomal subunits were found to possess characteristic electrophoretic mobilities in polyacrylamide-agarose composite gels and it is likely that some of the variations in subunit mobilities are related to differences in the size of the RNA which they contain.
TL;DR: Charge considerations, enzyme degradation studies, and labilities in acid and alkali lead to a structural assignment for MS I of guanosine 5'-diphosphate or 3'- or 2'-dphosphate (ppGpp).
TL;DR: The sequence of fifty-seven nucleotides in the coat protein cistron of phage R17 RNA directly confirms the genetic code, shows that the code used by the phage is degenerate and suggests that highly ordered base-paired structures exist in this RNA.
Abstract: The sequence of fifty-seven nucleotides in the coat protein cistron of phage R17 RNA directly confirms the genetic code, shows that the code used by the phage is degenerate and suggests that highly ordered base-paired structures exist in this RNA. Such base-paired loops may be involved in regulation of cistron expression and packing of the RNA in the phage particle.
TL;DR: An early function in translation is shown to be rate limiting at the elevated temperature and is the cause of polyribosome disaggregation and an RNA factor is produced which appears to promote the association of ribosomes with messenger RNA.
TL;DR: The synthesis of RNA associated with the mitochondria of HeLa cells is selectively inhibited by relatively low concentrations of ethidium bromide, and the ethidiumsensitive RNA does not appear on membrane-associated polyribosomes.
TL;DR: An examination of messenger RNA relatively specific for the lactose operon suggests that specific chromosomal genes may diverge more or less than the genome as a whole and Ribosomal ribonucleic acid (RNA)-specific sequences are conserved among most enterobacteria.
Abstract: Polynucleotide relationships were examined among many representatives of the Enterobacteriaceae by means of agar, membrane filter, and hydroxyapatite procedures. The amount of deoxyribonucleic acid (DNA) that reassociated was dependent, especially in interspecific reactions, on the annealing temperature. In only three cases: Escherichia coli-Shigella flexneri, Salmonella typhimurium-S. typhi, and Proteus mirabilis-P. vulgaris, was relative interspecific duplex formation 80% or higher. In most cases interspecies DNA duplex formation was 40% or less of that obtained from intraspecies DNA reassociation reactions. The stability of E. coli-S. flexneri DNA duplexes formed at either 60 or 75 C was virtually identical to that of homologous E. coli DNA duplexes, and the degree of interspecies duplex formation was minimally affected by the temperature increase (86% at 60 C; 77% at 75 C). The thermal stability of DNA duplexes formed at 60 C between DNA from E. coli and DNA from strains of Aerobacter aerogenes, S. typhimurium, S. typhi, and P. mirabilis was about 12 to 14 C below that of reassociated E. coli DNA. At 75 C, the formation of the interspecific DNA duplexes was markedly decreased, but the stability of the DNA able to reassociate at this temperature approximated that of reassociated E. coli DNA. The degree of reassociation and the thermal stability of E. coli-S. flexneri DNA duplexes suggests relatively little evolutionary divergence in these organisms. The other enterobacteria tested, however, have diverged to a point where less than one-half of their DNA can reanneal with E. coli DNA at 60 C and less than 10% reacts at 75 C. The degree of divergence between various enterobacteria does not appear to be uniform along the DNA molecule. Ribosomal ribonucleic acid (RNA)-specific sequences are conserved among most enterobacteria. An examination of messenger RNA relatively specific for the lactose operon suggests that specific chromosomal genes may diverge more or less than the genome as a whole.
TL;DR: The possible function of the protein-bound RNA in chick embryo chromatin is examined by experiments involving chromatin reconstitution and DNA-RNA hybridization of the template products.
TL;DR: It is infer that the complex comprises the specific portion of the cell membrane to which the DNA is attached within the cell, and this complex depends on the interaction of cell membrane components with the crystals of detergent.
TL;DR: The enzyme present in reovirus particles is thus a novel RNA transcriptase which transcribes double-stranded RNA in a manner analogous to that by which DNA-dependent RNA polymerase transcribes DNA.
TL;DR: If prepared free of the hybrid-degrading enzyme, RNA polymerase from calf thymus shows a fivefold increase in activity on denatured DNA as compared to native DNA.
Abstract: An enzyme present in extracts from calf thymus degrades specifically the RNA moiety of DNA-RNA hybrids. Other nucleic acids, such as single- or double-stranded DNA and single- or double-stranded RNA, are not affected to a comparable degree. If prepared free of the hybrid-degrading enzyme, RNA polymerase from calf thymus shows a fivefold increase in activity on denatured DNA as compared to native DNA.
TL;DR: Two major virus-specific RNA species were resolved in the cytoplasm of cultured human (KB) cells early after infection with adenovirus (Ad) type 2 and constitute a single class of RNA molecules whose transcription is not dependent upon virus specific early proteins.
TL;DR: Observations begin to establish a molecular basis for understanding the ability of T particles to interfere with the growth of B particles in Chinese hamster ovary cells.
Abstract: Plaque-forming B particles of vesicular stomatitis virus (VSV) induce the synthesis of virus-specific ribonucleic acid (RNA) in Chinese hamster ovary cells, whereas defective T particles do not. Infection with low input multiplicities of B results in the formation of four species of RNA. During infection with high multiplicities, RNA synthesis begins with mainly these four species of RNA but gradually shifts to a new pattern of RNA synthesis involving five other species of RNA. The change can also be induced by superinfection with T at 2.5 hr after infection with a low multiplicity of B. T added at the same time as B prevents virtually all RNA synthesis. Synthesis of the first group of RNA species correlates with the formation of B particles, whereas synthesis of the second group correlates with the formation of T particles. The various species of RNA formed after infection with VSV particles include single-stranded RNA, a completely double-stranded RNA, and RNA with partially double-stranded regions. These observations begin to establish a molecular basis for understanding the ability of T particles to interfere with the growth of B particles.
TL;DR: The phosphocellulose component of RNA polymerase binds the first nucleotide when synthesis of an RNA chain is initiated.
Abstract: The phosphocellulose component of RNA polymerase binds the first nucleotide when synthesis of an RNA chain is initiated
TL;DR: In this article, the number of 4, 18 and 26 s RNA cistrons present in purified nuclear and mitochondrial DNA of Saccharomyces cerevisiae has been determined and the significance of these findings to the continuous synthesis of ribosomal RNA during the cell cycle of yeast is discussed.
TL;DR: The suppression of polyadenylate synthesis by relatively low doses of actinomycin D suggests that it may be synthesized on a DNA template.
TL;DR: The 9S RNA fraction of mouse reticulocyte polysomes has been purified and shown to direct the synthesis of mouse hemoglobin β- chains in a mammalian cell-free system under the direction of a mRNA isolated from a different mammalian species.
TL;DR: Double-stranded RNA has been isolated from chick cells and chick cells infected with vaccinia virus and induces production of interferon.
Abstract: Double-stranded RNA has been isolated from chick cells and chick cells infected with vaccinia virus. The double-stranded vaccinia virus RNA induces production of interferon.
TL;DR: Cordycepin is an analogue of adenosine lacking the 3'-OH that prevents further elongation, thus producing a prematurely terminated RNA molecule that is unaffected by the drug.
Abstract: Cordycepin is an analogue of adenosine lacking the 39-OH When incorporated into a growing RNA molecule, cordycepin prevents further elongation, thus producing a prematurely terminated RNA molecule When HeLa cells are exposed to low concentrations of cordycepin, DNA and protein synthesis are unaffected during short exposure periods The synthesis of completed ribosomal and ribosomal-precursor (45S) RNA is significantly depressed Partially completed 45S ribosomal precursor molecules accumulate in the nucleolus 18S ribosomal RNA can be cleaved from these incomplete precursors, while 32S ribosomal precursor cannot be produced from partially snythesized 45S molecules The synthesis of transfer RNA is also reduced in the presence of cordycepin The synthesis of the nuclear heterogeneous RNA species is unaffected by the drug while the cytoplasmic heterogeneous RNA is slightly reduced