Showing papers on "Transcription (biology) published in 1971"

Two types of ribosome in mouse-hamster hybrid cells.

Abstract: ONLY mouse 28S ribosomal RNA (rRNA) can be detected in mouse-human hybrid cells1. Because these cells contain as many as thirty-five human chromosomes, including those believed to have ribosomal RNA genes, it has been suggested that the transcription of human ribosomal RNA genes may be repressed. Similar studies have not been performed with mouse-hamster hybrid cells because hamster and mouse 28S rRNAs have only a very small difference in their electro-phoretic mobilities2. We have now made use of the observation that free ribosomes (not engaged in translation) from hamster cells form dimers in conditions where mouse free ribosomes remain as monomers3 to determine whether mouse-hamster hybrid cells contain free ribosomes as monomers, dimers or as both.

An Adenylic Acid-Rich Sequence in Messenger RNA of HeLa Cells and Its Possible Relationship to Reiterated Sites in DNA

Abstract: Messenger RNA from HeLa cells contains, as part of the polynucleotide chain, RNase-resistant sequences that are labeled by adenosine but not by uridine. Heterogeneous nuclear RNA also contains adenylate-rich RNase-resistant regions, but in lower proportion than messenger RNA. Hybridization to DNA of 32P-labeled messenger RNA reveals that some of the adenylate-rich region is included in the rapidly-hybridizing fraction.

Reiteration and Clustering of DNA Sequences Complementary to Histone Messenger RNA

Abstract: The DNA complements of 9S messenger RNA thought to code for histones in sea urchins are reiterated, closely clustered, relatively stable in evolution and development and potentially separable from other nuclear DNA.

Lac DNA, RNA polymerase and cyclic AMP receptor protein, cyclic AMP, lac repressor and inducer are the essential elements for controlled lac transcription.

Abstract: A cell free system has been developed in which only the components of the lactose operon are required for its transcription. Results obtained with this system suggest that the DNA of the operon contains a new regulator site, at which the cyclic AMP control system acts.

Transcription of Mammalian Chromatin by Mammalian DNA-Dependent RNA Polymerases

Abstract: The transcription of rat-liver chromatin has been studied using partially purified from AI and highly purified form B DNA-dependent RNA polymerases isolated from rat liver. Chromatin contains endogenous RNA polymerase activity. This activity is evident only when the RNA polymerase assays are carried out at high ionic strength and its appearance as the ionic-strenght increases is thought to be due to the removal of chromatin-associated proteins which block further transcription by the bound enzyme. This activity is insensitive to the rifampicin derivative AF/0-13 which is shown to inhibit initiation of RNA synthesis by mammalian RNA polymerases. From AI polymerase is virtually inactive in the transcription of chromatin whereas the from B RNA polymerase (α-amanitin sensitive) actively transcibes chromatin. This activity has two salt concentration optima: (a) 0.01 M (NH4)2SO4 or 0.03 M KCI; (b) 0.16 M (NH4)2SO4 or 0.25 MKCI. Both these activities are inhibited by rifampicin AF/0-13. A comparison of the activity of the rat-liver from B polymerase and the Micrococcus lysodeikticus RNA polymerase demonstrates that chromatin is a more efficent template for the rat-liver enzyme. Evidence is presented that the rat-liver form B and the Micrococcus lysodeikticus RNA polymerases bind to and transcribe from different sites on the chromatin DNA.

Symmetrical In Vivo Transcription of Mitochondrial DNA in HeLa Cells

Abstract: RNA·DNA hybridization experiments utilizing separated strands of HeLa mitochondrial DNA and mit-RNA from HeLa cells exposed to short pulses of [5-3H]uridine have shown that the labeled RNA hybridizes with both the light (L) and the heavy (H) strand, though to a different relative extent depending upon the labeling time. Thus, hybridization of pulse-labeled RNA is about equal with the two strands when the pulse is very short (1-5 min), and becomes more and more predominant with the H strand with increasing pulse length. Pulse-labeled fast-sedimenting mit-RNA forms RNase-resistant double-stranded structures up to more than 5 μm long when self-annealed or annealed with an excess of unlabeled mit-RNA. These observations and the previous evidence of complete transcription of the H strand strongly suggest that mit-DNA is transcribed in HeLa cells symmetrically over a considerable portion of its length, with the transcript of the L strand being rapidly degraded or otherwise removed from the mitochondrial fraction.

Different template specificities of phage T3 and T7 RNA polymerases.

Abstract: THE transcription of the late genes of phage T7 depends on the function of gene 1 of the phage1. Chamberlin et al.2 have separated the gene 1 product from the host enzyme in Escherichia coli and have shown that gene 1 codes for an entirely new RNA polymerase whioii transcribes T7 DNA efficiently and exclusively compared with other templates. Summers and Siegel3 have shown that this enzyme transcribes the late region of the T7 genome.

Interferon action: inhibition of vesicular stomatitis virus RNA synthesis induced by virion-bound polymerase.

Abstract: The particle-bound RNA polymerase activity of vesicular stomatitis virus (VSV) can be demonstrated in vivo. Linear synthesis of viral RNA persists for 5 to 6 hours at 34°C in infected monolayers of chick embryo cells treated with cycloheximide and actinomycin D to block synthesis of protein and cell-specific RNA. At least 55 percent of the RNA made under these conditions is complementary to virion RNA. RNA synthesis mediated by VSV polymerase activity is inhibited in cells first treated with chick-derived interferon or polyriboinosinate• polyribocytidylate, but not by mouse interferon. The RNA product of VSV polymerase activity is present throughout the cytoplasm, and its synthesis is inhibited by the interferon system, as judged by autoradiographs that show the physical distribution, in cells, of RNA produced by virion polymerase in the absence of translation—a demonstration of the transcription product of the viral genome.

Transcription of Nonrepeated DNA in Mouse Brain

Abstract: Under normal conditions of DNA renaturation, about 60 percent of mouse DNA fragments renature at a rate consistent with their being present only once per sperm. These nonrepeated sequences (also called single-copy or unique) may be used in RNA-DNA hybridization experiments to provide quantitative estimates of RNA diversity. About 10 percent of the mouse single-copy sequences are transcribed in mouse brain tissue. Estimates of about 3 percent were obtained for mouse liver and kidney RNA's. If only one of the complementary DNA strands is transcribed, this hybridization value implies that the equivalent of at least 300,000 different sequences of 1000 nucleotides are expressed in mouse brain tissue. It is suggested that the large amount of DNA in mammals is functionally important, and that a substantial proportion of the genome is expressed in the brain.

Covalently linked RNA-DNA molecule as initial product of RNA tumour virus DNA polymerase.

Abstract: Reverse transcriptase from avian myeloblastosis virus initially synthesizes from endogenous RNA template a covalently linked DNA–RNA species, which Verma et al. suggest contains a small RNA primer molecule.

Regulation of the Synthesis and the Stability of Ribosomal RNA during Contact Inhibition of Growth

Abstract: The synthesis of rRNA precursors, and by implication RNA accumulation and cellular growth, may be regulated through a mechanism which controls the time taken for transcription of these molecules.

Inhibitors of the RNA and DNA Dependent Polymerase Activities of RNA Tumour Viruses

Abstract: RNA viruses of several animal leukaemias and sarcomas possess what seems so far to be a unique enzyme—an RNA dependent DNA polymerase1–6. Specific inhibitors of the viral enzyme will not only be useful in the analysis of its possible role in neoplasia, but might provide drugs for leukaemia and cancer therapy.

Ultraviolet Light-induced Formation of Pisatin and Phenylalanine Ammonia Lyase.

Abstract: The production of pisatin is induced3 in pea tissue by various plant pathogens (4, 8). This de novo synthesis can also be induced by an array of chemicals (9, 19, 22), most of which are known to have an affinity for double stranded DNA. Also, most of the inducers of pisatin or phenylalanine ammonia lyase (PAL)', EC 4.3.1.5 (a key enzyme in the biosynthesis of pisatin) have the potential to change the conformation of DNA. The induction of both pisatin and PAL is dependent on new RNA and protein synthesis (9, 22). We have proposed (9, 22) that the control of these cellular responses occurs at the gene transcription level and depends on the conformational state of the double stranded DNA (i.e., the DNA becomes more transcribable either by dissociating a repressor component or by assuming a more desirable conformation for transcription). If conformational changes in cellular DNA do, in fact, initiate this response, ultraviolet light which can dimerize thymidine bases and cause lesions in DNA (5, 23) should also influence this response. This paper describes the induced synthesis of pisatin and PAL by ultraviolet light.

Regulation of lac mRNA Synthesis in a Soluble Cell-free System

Abstract: A system has been developed to study the regulation of the lactose operon in vitro. Transcription requires cyclic AMP and cyclic AMP binding protein and is repressed by lactose repressor protein.

Poly A sequences at the 3' termini of rabbit globin mRNAs.

Abstract: Two eukaryotic mRNAs carry untranslated poly A sequences on the 3′ terminal region, suggesting that they have been conserved during evolution and may play a role in mRNA maturation after transcription.

Synthesis of Virus-Specific Ribonucleic Acid in KB Cells Infected with Type 2 Adenovirus

Abstract: By using the technique of deoxyribonucleic acid (DNA)-ribonucleic acid (RNA) hybridization, virus-specific RNA (cRNA) was detected 6 hr after infection in preparations of total RNA from cells infected with type 2 adenovirus in the presence of 2 μm 5-fluorodeoxyuridine. In the absence of 5-fluorodeoxyuridine, there was a continuous increase in the incorporation of 3H-uridine into viral cRNA until 20 hr after infection, at which time approximately 40% of the 3H-uridine entering RNA was found in virus-specific RNA. When RNA was prepared from polyribosome fractions obtained from cytoplasmic extracts of infected cells, virus-directed transcription was detected at 3 hr after infection (i.e., 3 to 4 hr before the initiation of viral DNA synthesis). Viral cRNA species synthesized at different times after infection were compared by the technique of DNA-RNA hybridization-inhibition (“presaturation” hybridization-competition). Three hybridization-inhibition techniques were compared. The techniques differed in the manner in which the DNA-RNA complex was isolated after the first hybridization reaction. Depending on the procedure employed, various degrees of inhibition were measured. The variation could be essentially eliminated if prior to hybridization the inhibitory RNA species were alkali-degraded to a uniform size of about 4S. Undegraded RNA could be used if the DNA-RNA complex was isolated by using a procedure involving rigorous washing (preferably including ribonuclease treatment) before the second hybridization with labeled RNA. When a rigorous hybridization-inhibition procedure was used, three classes of virus-specific RNA species could be distinguished: (i) early RNA class I whose synthesis began prior to viral DNA replication and stopped at some time after the initiation of viral DNA replication—it comprised about 70% of the early RNA species and was apparently degraded by 18 hr after infection; (ii) early RNA class II whose synthesis began prior to viral DNA replication and apparently continued at an enhanced rate late in infection; and (iii) late RNA whose synthesis began after the initiation of viral DNA synthesis.

Ribonucleic acid maturation in animal cells.

Abstract: Publisher Summary This chapter discusses that the animal cell is known to contain a great variety of RNA molecules of varying chain length. In addition to the small tRNA's and the larger ribosomal RNA's, there are other species whose existence is ephemeral. Although some of these may represent short-lived messengers, there is sufficient evidence to conclude that certain of these types are intermediates in biosynthetic pathways leading to the formation of transfer and ribosomal RNA's. It reviews that the primary structure of these intermediates is modified in certain instances by cellular enzyme systems subsequent to the completion of its primary synthesis in the processes of “transcription.” Such modifications include “trimming” or “tailoring,” that is alteration to the length of the primary transcription product by scission mechanisms, or the alteration of primary nucleotide sequences as a result of base or sugar moiety modification. This chemical work carried out by the cell is prerequisite in the formation of certain major nucleic acid species and the molecular events involved are collectively described as maturation events. It concludes that discussions can be made for and against RNA maturation processes being beneficial to higher organisms, but at the moment these are only hypothetical and no convincing evidence is available to support any one in particular.

Inhibition of RNA polymerase by streptolydigin.

Abstract: The antibiotic streptolydigin inhibits RNA polymerase by reducing the rate of RNA chain growth. It does not affect the fidelity of transcription.

Uptake of nonviral nucleic acids by mammalian cells.

Abstract: Publisher Summary This chapter discusses that the genetic information in DNA for making proteins is first transcribed into a messenger RNA. It is believed that cells of different histogenetic type in an organism contain identical DNA's but different mRN's. Numerous attempts have therefore been made to induce somatic changes in mammalian cells with RNA. The chapter discusses the effects of nucleic acids in mammalian cells: (1) specific biochemical effects of DNA, (2) DNA-induced transformation, (3) adverse effect of DNA or RNA on tumors, or induction of tumors by them, (4) specific immunological effects of DNA, (5) protective effect of DNA or RNA on irradiated animals. (6) induction of the synthesis of specific proteins, or stimulation of RNA synthesis, by RNA, (7) transfer of learning through RNA, (8) specific stimulation of growth or of mitosis by RNA, (9) induction of a morphological change or of differentiation by RNA, (10) other miscellaneous biological effects of DNA and RNA. It concludes that a more careful study of the induction of specific biochemical changes by RNA in vitro , using well-characterized, undegraded RNA which is likely to contain mRNA.

Interferon and transcription of early virus-specific RNA in cells infected with simian virus 40.

Abstract: Treatment with interferon reduced the content of early virus-specific RNA, as well as the content of an early viral protein (T antigen), in monkey cells acutely infected with simian virus 40 (SV40). This unexpected finding suggests either that the action of interferon involves inhibition of the transcription of early SV40 messenger RNA, or that the SV40 genome contains a “proto-early” gene whose product is required for the transcription of the remaining early genes.

Transcription of the polyoma virus genome: synthesis and cleavage of giant late polyoma-specific RNA.

Abstract: The size of virus-specific RNA synthesized in cultured mouse kidney cells infected with polyoma virus was estimated by electrophoresis and sedimentation analysis of RNA extracts from whole cells. Newly synthesized “late” polyoma-specific RNA appears as “giant” molecules of heterogeneous size, up to several times larger than a strand of polyoma DNA (1.5 × 106 daltons). Treatment with dimethylsulfoxide or urea showed that the large size of these molecules is not due to aggregation. Giant polyoma-specific RNA is strikingly similar in size distribution to “nuclear messenger-like” RNA (“heterogeneous nuclear” RNA) of the host cell. Subsequent to its synthesis, some of the giant polyoma-specific RNA appears to be cleaved to at least three smaller species.