Showing papers on "Genome published in 1972"
TL;DR: Acidic proteins associated with the DNA of oviduct cells seem to possess tissue specificity and to contain the binding sites for progesterone.
Abstract: Acidic proteins associated with the DNA of oviduct cells seem to possess tissue specificity and to contain the binding sites for progesterone.
224 citations
TL;DR: It is suggested that the EBV DNA in Raji cells is not covalently linked to the large chromosomal DNA, although the number of viral genomes per cell remains constant during passage, and that small fragments of cell DNA are bonded to the viral DNA.
Abstract: AT least four established human lymphocyte cell lines, one that originates from a Burkitt's lymphoma and the others from normal persons, contain Epstein-Barr virus (EBV) genome1. These cells show no viral antigens by immunofluorescence tests nor do they produce virus particles. We are examining one of the four cell lines, Raji (cells from a Burkitt's lymphoma), in more detail. The DNA isolated from purified Raji chromosomes contains as much virus genome as the DNA extracted from whole cells (65 genome equivalents per cell)1. The viral DNA therefore seems to be in the chromosomes. This result, however, does not necessarily indicate that the viral DNA is physically integrated into chromosomal DNA. The following experiments suggest that the EBV DNA in Raji cells is not covalently linked to the large chromosomal DNA, although the number of viral genomes per cell remains constant during passage. The results do not, however, exclude the possibility that small fragments of cell DNA are bonded to the viral DNA. The data also indicate that EBV DNA in Raji cells exists in strands of complete or nearly complete size.
182 citations
TL;DR: This simple theory provides a function for non-histone proteins and an explanation for the large size of eukaryotic genomes, repetitive sequences in DNA, HnRNA and “processing” of nuclear RNA.
Abstract: This simple theory provides a function for non-histone proteins and an explanation for the large size of eukaryotic genomes, repetitive sequences in DNA, HnRNA and “processing” of nuclear RNA.
162 citations
TL;DR: The cellular DNA's of Dictyostelium discoideum have been characterized by their behavior in CsCl buoyant density-gradient centrifugation and by their renaturation kinetics and the complexity of the nuclear DNA is but 11 times that of Escherichia coli.
154 citations
TL;DR: It is inferred that Mu-1 can integrate at a very large number of chromosomal sites, which makes it distinct from other known temperate coliphages; the lambdoid phages attach at a particular site, P2 phage attaches at a limited number of sites and P1 resides in the cell as a plasmid6.
Abstract: THE temperate bacteriophage Mu-1 can induce mutations at many different loci in the genome of its host bacterium Escherichia coli K12 (see ref. 1). The mutations are assumed to arise by the insertion of Mu-1 DNA within the affected genes, as the sites of mutations are inseparable from the prophage sites by genetic criteria2, 3. It has been inferred therefore that Mu-1 can integrate at a very large number of chromosomal sites. This attribute of Mu-1 makes it distinct from other known temperate coliphages; the lambdoid phages attach at a particular site4, P2 phage attaches at a limited number of sites5 and P1 resides in the cell as a plasmid6.
148 citations
TL;DR: In this article, a technique consisting of hybridizing DNA from the cells concerned with the complementary RNA (cRNA) obtained by the transcription of EB virus DNA in vitro with E. coli RNA polymerase was proposed.
Abstract: DURING the past two years, work in this and other laboratories has demonstrated viral genomes characteristic of Epstein–Barr (EB) virus in cell lines and biopsy cells derived from Burkitt lymphomas1–4, and anaplastic carcinomas of the nasopharynx5. Our technique consists of hybridizing DNA from the cells concerned with the complementary RNA (cRNA) obtained by the transcription of EB virus DNA in vitro with E. coli RNA polymerase. We have now applied the technique to various lymphoblastoid cell lines which lack virus particle and structural viral antigens and found that they all seem to carry EB virus genomes. DNA from human umbilical cord leucocytes, however, seems to be free of such genomes.
134 citations
TL;DR: Chromosome pairing in hybrids involving Triticum aestivum and new accessions of T. speltoides and in an amphiploid of these species indicates that T. Speltoide can no longer be considered to be the donor of the B genome of the polyploid wheats, requiring a reconsideration of the genome relationships and evolutionary processes that gave rise to cultivated wheats.
Abstract: Chromosome pairing in hybrids involving Triticum aestivum and new accessions of T. speltoides, and in an amphiploid of these species, indicates that T. speltoides can no longer be considered to be the donor of the B genome of the polyploid wheats. This necessitates a reconsideration of the genome relationships and evolutionary processes that gave rise to cultivated wheats.
131 citations
TL;DR: Unlike the case of mouse, human heterochromatin is composed of a variety of DNA families, and mapping human chromosomes by nucleic-acid hybridization appears feasible, the results suggest that repeated sequences in the DNA of the human genome suggest the heterogeneity of the repeated sequences.
122 citations
TL;DR: It is shown that in experiments performed in conditions of DNA excess, Bishop et al. obtained a much lower estimate, of about five globin genes per genome, when duck 9S RNA was hybridized to excess duck DNA.
Abstract: IT is crucial to all our ideas about the structure of eukaryotic chromosomes that we should have estimates of the numbers of copies of typical genes in the genome. Genetic evidence argues for a single copy of each gene but this is difficult to reconcile with experimental evidence that some genes, for example those specifying histones1 and ribosomal RNA2, are reiterated some hundreds or thousands of times without significant divergencies. In a previous report from this laboratory3, it was estimated that globin mRNA hybridized with an amount of DNA corresponding to 50,000 copies of globin genes. These experiments were performed in conditions of RNA excess and the hybrids were of poor quality; hence they were probably relatively non-specific and the results are readily explained in terms of hybridization of a component of the RNA with a family of repetitive sequences4. Similar considerations also apply to the estimate of 60,000 copies of globin genes obtained by hybridization of avian blood 10S RNA5. More recently, in experiments performed in conditions of DNA excess, Bishop et al.6 obtained a much lower estimate, of about five globin genes per genome, when duck 9S RNA was hybridized to excess duck DNA. These experiments have been criticized7 because the relationship between the rate constants for RNA–DNA and DNA–DNA hybridization reactions is uncertain and could be changed by partial degradation of RNA; moreover, a considerable fraction of the RNA remained unreacted in the presence of excess DNA even at very high C0t values (the product of concentration of nucleic acid and incubation time expressed as mole nucleotide per litre × s).
116 citations
TL;DR: The numbers of gene (codon) differences per locus between two randomly chosen genomes within and between Caucasian, Negro, and Japanese populations have been estimated from gene frequency data for protein loci.
Abstract: The numbers of gene (codon) differences per locus between two randomly chosen genomes within and between Caucasian, Negro, and Japanese populations have been estimated from gene frequency data for protein loci. The estimated number of gene differences between individuals from different populations is only slightly greater than the number between individuals from the same population.
TL;DR: Ritonucleic acid extracted from four stages during the developmental cycle of the cellular slime mold Dictyostelium discoideum was hybridized with purified single-copy nuclear DNA, indicating that there are, during development, qualitative and quantitative changes in the portion of the single- copies of the genome transcribed.
TL;DR: The 70S genome of two RNA tumor viruses, murine sarcoma virus and avian myeloblastosis virus, binds to Millipore filters in buffer with high salt concentration and to glass fiber filters containing poly(U), suggesting that 70S RNA contains adenylic acid-rich sequences.
Abstract: The 70S genome of two RNA tumor viruses, murine sarcoma virus and avian myeloblastosis virus, binds to Millipore filters in buffer with high salt concentration and to glass fiber filters containing poly(U). These observations suggest that 70S RNA contains adenylic acid-rich sequences. When digested by pancreatic RNase, 70S RNA of murine sarcoma virus yielded poly(A) sequences that contain 91% adenylic acid. These poly(A) sequences sedimented as a relatively homogenous peak in sucrose gradients with a sedimentation coefficient of 4-5 S, but had a mobility during polyacrylamide gel electrophoresis that corresponds to molecules that sediment at 6-7 S. If we estimate a molecular weight for each sequence of 30,000-60,000 (100-200 nucleotides) and a molecular weight for viral 70S RNA of 3-12 million, each viral genome could contain 1-8 poly(A) sequences. Possible functions of poly(A) in the infecting viral RNA may include a role in the initiation of viral DNA or RNA synthesis, in protein maturation, or in the assembly of the viral genome.
TL;DR: Kinetic analysis of the hybridization of 71S RNA from Prague strain of Rous sarcoma virus with an excess of DNA from virus induced sarcomas indicated the presence of the majority of the viral genome sequences in cellular DNA with a very low average frequency per cell.
Abstract: Kinetic analysis of the hybridization of 71S RNA from Prague strain of Rous sarcoma virus with an excess of DNA from virus induced sarcomas indicated the presence of the majority of the viral genome sequences in cellular DNA with a very low average frequency per cell. About one-third of the viral sequences were at least partially complementary to DNA sequences with a higher average frequency on the order of 50 to 100 per cell. Normal chick embryo DNA was distinctly different, but contained sequences at least partially homologous to some fraction of the viral RNA.
TL;DR: Protein electrophoretic profiles cast doubt upon the prevalent theory that the B genome of the polyploid wheats was derived from a species of Aegilops, and suggest that the wild tetraploids wheats comprise a complex, whose components were derived from various combinations of diploid Triticum types.
Abstract: Protein electrophoretic profiles cast doubt upon the prevalent theory that the B genome of the polyploid wheats was derived from a species of Aegilops. They suggest, instead, that the wild tetraploid wheats comprise a complex, whose components were derived from various combinations of diploid Triticum types, which evidently include the B-genome type.
TL;DR: The repetitive segments of the middle-repetitive portion of the DNA of Drosophila melanogaster have been found to be 150 base pairs or somewhat less in length.
TL;DR: The focus of this review is on the micronucleus and macron nucleus in the ciliated protozoa and the organization and function of the DNA molecules within them and it is concluded that the size of the genome is not reduced in the macronuclear units.
Abstract: The focus of this review is on the micronucleus and macronucleus in the ciliated protozoa and the organization and function of the DNA molecules within them. We present (1) some of the structural and functional differences which are known, (2) the genetic evidence for macronuclear units, (3) two hypotheses for the organization of the DNA molecules in the macronucleus to explain these units, and (4) experiments designed to discriminate between these hypotheses. We conclude that the size of the genome is not reduced in the macronucleus and that there are 45 copies of the haploid genome present in the macronucleus of normal strains of Tetrahymena pyriformis and 800 copies in the macronucleus of Paramecium aurelia. The ciliate genome is relatively simple in terms of repeated sequences. However, not all copies of the genes present in the macronucleus may be identical since fractions of differing thermal stability appear after renaturation.
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TL;DR: Nuclear DNA amounts of twenty-three species of birds from seventeen families of seven orders were determined by Feulgen cytophotometry, indicating an evolutionary control of genome size regardless of chromosome number.
Abstract: Nuclear DNA amounts of twenty-three species of birds from seventeen families of seven orders were determined by Feulgen cytophotometry. Genome size is constant in these birds, the ratio between the largest and smallest genome in the sample is 1.3 to 1. The modal diploid DNA amount for birds is about 3.6 picograms, slightly higher than previously reported. The data point towards an evolutionary control of genome size regardless of chromosome number. Birds represent an example of a group in which reduction of genome size is correlated with active speciation.
TL;DR: The creation of additional regulatory systems contributed more to big leaps in evolution than did the creation of new structural genes, because the necessary increase in the number of regulatory systems had to be compensated by simplification of each regulatory system.
Journal Article•
TL;DR: It is deduced that the BTV genome is fully transcribed both in vitro and in vivo by an enzyme present in the viral capsid.
Abstract: VERWOERD, D. W. & HUISMANS, H . Studies on the in vitro and the in vivo transcription of the bluetongue virus genome. Onderstepoort ] . vet. Res. 39 (4) 185-192 (1972). Bluetongue virus particles, converted to a high density form by the selective removal of two polypeptides from their protein capsids, possess RNA dependent RNA polymerase activity. The enzyme, which can be assayed by its ability to incorporate nucleoside triphosphates into RNA in an in vitro system, is dependent on magnesium ions, is stimulated by the presence of manganese ions and shows maximal activity at 28°C. The product of the in vitro reaction was isolated and shown to consist of ten singlestranded RNA segments which can be hybridized with double-stranded RNA isolated from purified bluetongue virus (BTV). The hybridization product, when analyzed by means of polyacrylamide gel electrophoresis, is indistinguishable from a hybrid obtained using BTV messenger RNA isolated from infected cells. It is therefore deduced that the BTV genome is fully transcribed both in vitro and in vivo by an enzyme present in the viral capsid.
TL;DR: The structure ofPhage Particles and Infection and Phage Development, as well as protein products, and phage protein synthesis in E.coli cells are described.
Abstract: GENERAL PROPERTIES OF RNA COLIPHAGES ...... ..................... 110 Structure ofPhage Particles ................................................. 110 Infection and Phage Development .......................................... 110 PHAGE GENES AND THEIR PRODUCTS ........ .......................... 112 Identification ofPhage Genes .............................................. 112 Gene Order ........................................................ 113 Gene Products ........................................................ 114 PHAGE PROTEIN SYNTHESIS IN INFECTED CELLS ..... ................ 114 Infection with Wild-Type Phage ............................................. 114 Infection with Phage Mutants .............................................. 115 PHAGE PROTEIN SYNTHESIS IN E. COLIEXTRACTS.. 117 Protein Products ..................................................... 117
TL;DR: A unique distribution of antigens in embryonic tissues of several species was detected, and in addition, antigen expression in tissues appears to be controlled by a dominant gene.
Abstract: Antigenic markers associated with the major internal protein of RNA tumor viruses of the C-type have proven extremely useful in natural history studies of these viruses. This protein possesses species-specific antigenic determinants, and, in the case of mammalian C-type viruses, the protein possesses crossreactive determinants as well. These determinants are, thus, useful for species identification and classification of mammalian viruses. A unique distribution of antigens in embryonic tissues of several species (where tests are available) was detected, and in addition, antigen expression in tissues appears to be controlled by a dominant gene. These data have contributed greatly to the theory that RNA tumor-virus information is inherited as part of the cellular genome.
TL;DR: Several hybrid lines between human and mouse somatic cells, containing one or two complements of mouse chromosomes and a reduced complement of human chromosomes, have been examined for the presence of mouse and human mitochondrial DNAs.
Abstract: Several hybrid lines between human and mouse somatic cells, containing one or two complements of mouse chromosomes and a reduced complement of human chromosomes, have been examined for the presence of mouse and human mitochondrial DNAs. For this analysis, advantage was taken of the fact that these two types of mitochondrial DNA have a buoyant density difference in CsCl gradients of 0.008 g/cm3. In all the hybrid clones analyzed, which retained an average number of human chromosomes estimated conservatively to vary from 5 to 23, only mitochondrial DNA of mouse character was detected. It seems likely that either repression of relevant human genes by the mouse genome or loss of human chromosomes is responsible for these results. If the latter explanation is true, since chromosome loss under the conditions used here was substantially a random process, one would have to assume that the activity of nuclear genes distributed in many chromosomes is required for the survival of mitochondrial DNA.
TL;DR: In the first application of this approach, a prophage genome containing 9% excess DNA is constructed, whose density and rate of heat inactivation indicate they contain the complete genome in a normal capsid.
TL;DR: Complete hybrids of simian virus 40 (SV40)DNA and its complementary RNA (cRNA) are not retained on nitrocellulose membranes at saturating cRNA concentrations, which indicates incomplete homology between DNA and RNA.
Abstract: Complete hybrids of simian virus 40 (SV40)DNA and its complementary RNA (cRNA) are not retained on nitrocellulose membranes. At saturating cRNA concentrations, retention of the hybrids indicates incomplete homology between DNA and RNA, probably due to incorporation of host DNA in the viral DNA; this effect is most pronounced when DNA is produced in cells infected at high multiplicity. Hybrids between DNA of Chinese hamster cells transformed by SV40 and cRNA are retained if the DNA fragments are long, but they are lost if the DNA is sheared to less than the length of an SV40 DNA molecule. Hence, in cells examined with about six SV40 genomes per cell, each genome is individually integrated. The results may explain previous discrepancies in the estimation of the number of viral genomes in transformed cells.
TL;DR: DNA extracted from macron nuclei of axenically cultured Paramecium aurelia has been characterized with regard to its kinetic complexity and it is suggested that the macronucleus contains ∼840 diploid copies of the slowly renaturing component.
Abstract: SYNOPSIS
DNA extracted from macronuclei of axenically cultured Paramecium aurelia has been characterized with regard to its kinetic complexity Renaturation of macronuclear DNA from this protozoon appeared to follow 2nd order kinetics and revealed the presence of 2 components: a main component comprising ∼96% of the genome which renatured slowly and a minor component comprising ∼4% of the genome which renatured at a rate ∼3000 faster than the main component The value of the kinetic complexity of the main component has been estimated at 38 × 1010 daltons and that of the minor component at 145 × 107 daltons It is suggested that the macronucleus contains ∼840 diploid copies of the slowly renaturing component; for each copy of the latter there are ∼100 copies of the fast renaturing component
TL;DR: This review will focus specifically on the various aspects of RNA metabolism as it relates to heptoid phage growth and development and five specific topics will be discussed: control of the "early to late switch" in phage tran scription; initiation and termination of phage transcription; control of host transcription; stabilization ofphage mRNA; and translational con trols in infected cells.
Abstract: INTRODUCTION Coliphage T7 (1, 2) is the prototype of a family of related viruses that includes T3 (3) and c/JII (4). By analogy to the lambdoid phage (5), one might coin the term "heptoid" to designate this group. Since these virulent phages are less com plex than the T-even coliphages, and since major features of their genetics and enzymology have been elucidated, these viruses are of increasing use in a wide range of molecular biological investigations. These viruses have double-stranded DNA genomes of about 25Xl06 daltons which code for about 25 genes. About half of these genes are used in coding for structural components of the virus. The remaining genes code for proteins neces sary for viral DNA synthesis and those regulatory functions that program phage development. An excellent current review by Studier (2) covers the genetics and physiology of phage T7, so this review will focus specifically on the various aspects of RNA metabolism as it relates to heptoid phage growth and development. Five specific topics will be discussed: (a) control of the "early to late switch" in phage tran scription; (b) initiation and termination of phage transcription; (c) control of host transcription; (d) stabilization of phage mRNA; and (e) translational con trols in infected cells. These topics represent areas of active research, some active controversies, and some aspects unique to heptoid phages.
TL;DR: Heterodisperse high molecular weight RNA synthesized by salivary glands hybridizes in situ specifically to the Balbiani rings ofSalivary gland chromosomes contains redundant sequences.