Showing papers on "Genome published in 1977"
TL;DR: It is apparent from these investigations that the two types of cRNA are synthesised by the same transcriptase but that the production of unpolyadenylated complete transcripts is dependent upon the synthesis of certain other viral protein(s).
250 citations
TL;DR: The high sensitivity of this technique, achieved through the use of 32P-labeled RNA of high specific activity, has led to the observation that hybridization of Ad2+ND1 RNA occurs at several locations on the Ad2 genome, in addition to the expected sites of hybridization proximal to the SV40 insertion.
224 citations
TL;DR: A model for viral gene expression is proposed which conforms to previous suggestions that eucaryotic cells initiate translations only at the 5′ termini of messenger RNAs.
197 citations
TL;DR: The existence of this sequence repetition immediately suggests mechanisms by which the growing DNA copy can jump from the 5' end to a 3' end of the template and become circular.
Abstract: When Rous sarcoma virus RNA is transcribed into DNA by the reverse transcriptase, a tRNA primer is elongated into DNA. The primer is near the 5' end of the virus genome; the first major DNA made is a "run-off" product extending 101 bases from the primer to the 5' end of the template. We have studied this DNA molecule to determine the sequence of the first 101 bases at the 5' end of the Rous sarcoma virus genome (Prague strain, subgroup C). Twenty-one bases at the extreme 5' end are also at the 3' end of the virus genome (see D. E. Schwartz, P. C. Zamecnik, and H. L. Weith, this issue, pp. 994-998), and thus this virus is terminally redundant. The existence of this sequence repetition immediately suggests mechanisms by which the growing DNA copy can jump from the 5' end to a 3' end of the template and become circular. The sequence also displays a possible ribosome binding site and enough secondary structure to permit a possible 5'-5' linkage of viral RNA molecules.
182 citations
TL;DR: The Prague strain, subgroup B of Rous sarcoma virus, was found to contain 11.6 ± 0.5 residues of m 6 Ap by quantitative analysis of 32 P-labeled virion RNA after complete RNAase digestion, which supports the mapping of a portion of the m 6 A residues in src and suggests that this methylation is specific to certain regions of the genome.
156 citations
TL;DR: Using a 3H-cDNA for RNA sequences specifically associated with murine intracisternal type A particles, the presence of reiterated sequence transcripts in poly(A) RNA from a neuroblastoma A particle fraction was confirmed by direct hybridization of the RNA with cellular DNA.
135 citations
TL;DR: The Friend strain of SFFV appears to be a recombinant between a portion of the F-MuLV genome and RNA sequences that are highly related to murine xenotropic viruses.
Abstract: The genome of the Friend strain of the spleen focus-forming virus (SFFV) has been analyzed by molecular hybridization. SFFV is composed of genetic sequences homologous to Friend type C helper virus (F-MuLV) and SFFV-specific sequences not present in F-MuLV. These SFFV-specific sequences are present in both the Friend and Rauscher strains of murine erythroleukemia virus. The SFFV-specific sequences are partially homologous to three separate strains of mouse xenotropic virus but not to several cloned mouse ecotropic viruses. Thus, the Friend strain of SFFV appears to be a recombinant between a portion of the F-MuLV genome and RNA sequences that are highly related to murine xenotropic viruses. The implications of the acquisition of the xenotropic virus-related sequences are discussed in relation to the leukemogenicity of SFFV, and a model for the pathogenicity of other murine leukemia-inducing viruses is proposed.
127 citations
TL;DR: The small RNAs of the Moloney murine leukemia virus (M-MuLV) were fractionated into at least 15 species by two-dimensional polyacrylamide gel electrophoresis as mentioned in this paper.
Abstract: The small RNAs of Moloney murine leukemia virus (M-MuLV) were fractionated into at least 15 species by two-dimensional polyacrylamide gel electrophoresis. The pattern of small RNAs is significantly different from that of Rous sarcoma virus. A subset of the virion small RNAs is associated with the genome RNA in the 70S complex. One of the associated molecules, a cellular tRNA, is tightly bound to the genome RNA and serves as the major primer for M-MuLV RNA-directed DNA synthesis in vitro.
125 citations
TL;DR: In this paper, the translational activity of the virus-like particle-derived double-stranded RNA (dsRNA) was analyzed in the wheat germ cell-free system and denaturation of the dsRNA immediately prior to in vitro translation resulted in the synthesis of one major and at least three minor polypeptides.
125 citations
TL;DR: A genetic map and a model for the generation of the Sendai DI-RNAs are presented, showing that almost all the sequences contained in the DI- RNAs derive from sequences that are contiguous to the 5' end of the nondefective (ND) genome.
113 citations
TL;DR: The primary focus will be on the SV40 genome itself, its structure as a DNA molecule and small chromosome, its genetic content, its replication and transcription, and its interaction with cellular chromosomes.
Abstract: Publisher Summary The essential feature of a virus is its nucleic acid genome, a cluster of genes that brings new information into the cell it infects. Depending on the circumstances of infection, expression of viral genes can lead to multiplication of the virus, and perhaps cell damage or to a stable virus-host cell relationship, in which the cell often acquires new properties. These characteristics of viruses, combining the simplicity of the genomic structure and easy manipulation with important cellular effects, accounts for their great usefulness in studying gene action and regulation in complex cells. Among the simplest tumor viruses are the small DNA-containing papo-vaviruses, including simian virus 40 (SV40), the murine polyoma virus, and the human papovaviruses BK and JC. These viruses exhibit similar physical and biological properties, and in some instances partial homology of DNA sequences. Therefore, although this chapter concentrates on SV40, the general features of genomic organization and function are likely to apply to all the small papo-vaviruses. SV40 occurs as an inapparent natural infection of certain species of Asiatic macaques and was discovered in rhesus monkey cell cultures as a vacuolating agent for African green monkey cells. The purpose of this chapter is to examine, in detail, some of the molecular events just outlined and to relate them to the structure and genetic organization of the SV40 genome. The primary focus will be on the SV40 genome itself, its structure as a DNA molecule and small chromosome, its genetic content, its replication and transcription, and its interaction with cellular chromosomes.
TL;DR: Evidence is presented suggesting that genes of higher eukaryotes correspond to much larger DNA segments than in microorganisms, and may well be restricted to small regions of the genome, possibly corresponding to the structural genes.
Abstract: THE size of the eukaryotic genome increases with the evolutionary complexity of the organism, although this relation is somewhat obscured by large differences in the haploid DNA content of closely related species Yet the total number of genes is believed to be fairly constant, suggesting that genes of higher eukaryotes correspond to much larger DNA segments than in microorganisms1 In that case, only a small fraction of each gene would code for the ultimate gene product, the remainder being ‘spacer’ DNA with still ill-defined functions The sequence coding for the gene product will be hereafter designated as the structural gene The complex organisation of chromatine in higher organisms raises the problem of its possible influence on the distribution of recombination events I shall present here evidence suggesting that they may well be restricted to small regions of the genome, possibly corresponding to the structural genes
TL;DR: The detection and recovery of SV40 genomes containing foreign DNA sequences can be facilitated, and the risk of accidental dispersal reduced, by in situ hybridization and radioautography.
Abstract: The detection and recovery of SV40 genomes containing foreign DNA sequences can be facilitated, and the risk of accidental dispersal reduced, by in situ hybridization and radioautography.
TL;DR: Contour-length measurements of both nondenatured and partially denatured DNA from purified extracellular human cytomegalovirus indicate that more than one size class of viral DNA is encapsidated.
Abstract: Contour-length measurements of both nondenatured and partially denatured DNA from purified extracellular human cytomegalovirus indicate that more than one size class of viral DNA is encapsidated. In addition to a size class averaging about 100 x 10(6) daltons, a much less abundant class of larger viral DNA molecules, 150 x 10(6) to 155 x 10(6) daltons, was extracted from purified extracellular virus. As predicted by melting-curve analysis, partial denaturation of human cytomegalovirus DNA generates denaturation maps showing distinctive adenine plus thymidine (A+T)-rich and guanine plus cytosine (G+C)-rich localizations. Alignment of partial denaturation maps of both 100 x 10(6)- and 150 x 10(6)- to 155 x 10(6)-dalton molecules from maximum overlap of common A+T- and G+C-rich zones clearly shows six unique zones contained in a length equal to the longest class, 150 x 10(6) to 155 x 10(6) daltons. However, various alignments of the smaller class of the molecules within the confines of the approximately 100 x 10(6)-dalton-length equivalent are nondistinctive. Of the six unique A+T- and G+C-rich zones, five are linked in a specific sequence and maintain the same relative orientation; these features indicate the absence of major inversions within these zones. The sixth unique zone may occur at either end of this five-zone series, but it was never found at both ends of the same molecule. Additionally, this terminal zone appears to undergo complete inversions at least at one end of the alignment, and perhaps at both. These data indicate that 150 x 10(6)- to 155 x 10(6)-dalton molecules comprise human cytomegalovirus-specific genetic information.
TL;DR: Results indicate that the ribosomal protein genes on lambdafus2 are organized into at least four transcription units, and evidence suggests that the genes for S3, S17, S19, L2, L4, L16, L22, L23, and L29 are part of a single transcription unit.
TL;DR: The sizes of the genomes of bacteriophages P1, P1Cm, and P7 (φAMP) and their corresponding plasmid prophages were measured by electron microscopy as mentioned in this paper.
TL;DR: An attempt is made to evaluate the phytochemical properties of the fruit extract of magnesia, which has the potential to have an impact on human health and disease.
Abstract: INTRODUCTION .... .. . ... . . . .. . . . . . . . . . . . .. . . . . . . . .. . . . . . . . . .. . . .. . . . 597 NAEGLERIA GRUBERI . . .... .. .... ... ... ... ......... ....... .. . . . . . . .. . . . . . . . ...... .. .. . . . . . . . . . . . . ..... 598 Amebae 600 Encystment and Excystment .... . .. . .. . .. . . .. . .... 601 Dijferentiation to Flagellates ... ......... . .. ... ...... ... 601 Place in Nature ....... .... . . . . . ... . . . 602 Genome ...... . .. .. . ... . . . . ... . .. .. . .. . .. . .. . . .. . .. . . 604
TL;DR: Chromatography on hydroxyapatite of HaeIII and HpaII digests of yeast mitochondrial DNA shows that 0·8×106 and 1×106 (molecular weight) of DNA per genome unit of 50×106, respectively, are present in the digests as short, single-stranded oligonucleotides, thus providing evidence for the clustering of both Hae sites and HPA sites as discussed by the authors.
TL;DR: Nine of the twenty-one chromosome pairs of the hexaploid wheat Triticum aestivum var.
Abstract: Nine of the twenty-one chromosome pairs of the hexaploid wheat Triticum aestivum var. Chinese Spring (genome constitution AABBDD) show distinctive N-banding patterns. These nine chromosomes are 4A, 7A and all of the B genome chromosomes. The remaining chromosomes show either faint bands or no bands at all. Tetraploid wheat, T. dicoccoides (AABB), showed banded chromosomes similar to those observed in the hexaploid. Of the diploid species T. monococcum, T. boeoticum, T. urartu and Aegilops sauarrosa showed little or no banding as would be expected of donors of the A and D genomes. Ae. speltoides had a number of N-banded chromosomes as would be expected of a candidate for the B genome donor. Since N-bands are not evident on some nucleolar organiser chromosomes, the staining specificity cannot be correlated with the presence of nucleolar organiser regions.
01 Jan 1977
TL;DR: Picornaviruses have long seemed to have many genes, but the size of the genome compared with the “average” gene product suggested about ten for poliovirus (Fenner, 1968), which causes at least a dozen synthetic and degenerative changes in the host cell.
Abstract: Picornaviruses have long seemed to have many genes. The size of the genome compared with the “average” gene product suggested about ten for poliovirus (Fenner, 1968), which causes at least a dozen synthetic and degenerative changes in the host cell. Many viral polypeptides are found, originally about 14 (Summers et al.,1965) and now more than 34 (Abraham and Cooper, 1975a). Other picornaviruses are very similar.
TL;DR: Non-glucosylated T4 DNA was digested with R. EcoRI and the resulting fragments covalently joined to λ vectors and the genetic content of each λ-T4 hybrid was determined by marker-rescue tests.
Abstract: Non-glucosylated T4 DNA was digested with R. EcoRI and the resulting fragments covalently joined to λ vectors. The genetic content of each λ-T4 hybrid was determined by marker-rescue tests. The isolation of many recombinants containing partialdigestion products of T4 DNA provided the overlapping sequences necessary to order fragments within the T4 genome. The present analyses include parts of the “early” region between genes 42 and 46, and much of the “late” region between genes 50 and 29. T4 cytosine-DNA digested to completion by R.EcoRI was used to identify the fragments of DNA within the λ-T4 recombinants. The T4 cytosine-DNA was also sensitive to R.HindIII and R.Xho but not to R.BamH1.
TL;DR: Coliphage λ is a temperate virus and a fraction of λ infected bacterial cells survive, and some of the survivors become lysogens, bacteria that have stably acquired two new properties, i.e., immunity to infection by a further challenge of virus and the capacity to produce infective virus.
Abstract: Coliphage λ is a temperate virus. A fraction of λ infected bacterial cells survive, and some of the survivors become lysogens. Lysogens are bacteria that have stably acquired two new properties, i.e., immunity to infection by a further challenge of virus and the capacity to produce infective virus. The new properties reflect the presence of λ prophage, the genome of λ virus as it occurs in lysogens. Lysogenization, the establishment of the prophage-containing state, was recognized early to depend on two potentially independent processes. First, lytic growth of the virus must be prevented or the infected cell will die. This process is accomplished primarily by λ repressor whose molecular basis of action and role in lysogeny are described in detail in recent reviews (Pirrotta, 1976); Ptashne et al., 1976). Second, the prophage must be made to replicate in parity with the host genome. For lysogens of phage λ, this is accomplished by the insertion of the entire viral genome into the host genome, forming a single continuous chromosome in which the viral DNA is replicated as part of the host genome.
TL;DR: The DNA sequences of human adenoviruses of subgroups B and C have significantly diverged in the course of viral evolution, but the complex organization of the adanovirus genome has been rigidly conserved.
Abstract: Cleavage sites of nine bacterial restriction endonucleases were mapped in the DNA of adenovirus type 3 (Ad3) and Ad7, representative serotypes of the "weakly oncogenic" subgroup B human adenoviruses. Of 94 sites mapped, 82 were common to both serotypes, in accord with the high overall sequence homology of DNA among members of the same subgroups. Of the sites in Ad3 and Ad7 DNA, fewer than 20% corresponded to mapped restriction sites in the DNA of Ad2 or Ad5. The latter serotypes represent the "nononcogenic" subgroup C, having only 10 to 20% overall sequence homology with the DNA of subgroup B adenoviruses. Hybridization mapping of viral mRNA from Ad7-infected cells resulted in a complex physical map that was nearly identical to the map of early and late gene clusters in Ad2 DNA. Thus the DNA sequences of human adenoviruses of subgroups B and C have significantly diverged in the course of viral evolution, but the complex organization of the adenovirus genome has been rigidly conserved.
TL;DR: A major fraction of the highly repeated DNA sequences from the Drosophila melanogaster genome has been isolated as well-defined satellites by buoyant density-centrifugation in CsCl gradients containing DNA-binding antibiotics, leading to the possibility of a chromosome-specific arrangement of satellite DNA.
TL;DR: This chapter investigates the events affecting cytoplasmic gene markers occurring in the zygote, and the distribution of cytogenes to the four meiotic products, and presents an overall picture of the segregation and recombinational behavior of the linked set of chloroplast genes that had been investigated.
Abstract: Publisher Summary This chapter focuses on genetic analysis and correlated physical studies of the chloroplast DNA of Chlamydomnas, particularly those aspects of the subject that have progressed in the past few years. Genetic analysis based on segregation and recombination has been carried out with biparental zygotes, either of spontaneous origin or UV-induced. A comparison of results from zygotes of bath types has been discussed. The chapter investigates (1) the events affecting cytoplasmic gene markers occurring in the zygote, and the distribution of cytogenes to the four meiotic products; (2) the events occurring in the first few mitotic doublings, examining each doubling independently by means of pedigree analysis; and (3) the events occurring over the range of doublings required before most of the heterozygous genes had segregated, examined in liquid cultures of zoospore clones. The chapter also presents an overall picture of the segregation and recombinational behavior of the linked set of chloroplast genes that had been investigated. Supporting data, including the results of a set of 25 multigene crosses have been included. The principal conclusions reached from the analysis of the 25 crosses listed in the chapter are: (1) Chloroplast genes of Chlamydomonas show maternal inheritance and can be identified by the transmission pattern. (2) Exceptional zygotes are of two types: biparental zygotes that transmit the chloroplast genome from both parents; and paternal zygotes, in which the maternal complement is lost. (3) Zoospores from biparental zygotes are usually, heterozygous for the entire genome, and are referred to as cytohets. The chapter discusses the frequencies of simultaneous coconversions of two or more genes that provide valuable mapping data.
TL;DR: The results of ribonuclease T1 oligonucleotide fingerprint analyses indicate that influenza virus messenger RNAs are incomplete transcripts of the corresponding genome RNAs and that in this respect they differ from the unpolyadenylated virus specific complementary RNAs obtained from infected cells.
Abstract: The results of ribonuclease T1 oligonucleotide fingerprint analyses indicate that influenza virus messenger RNAs are incomplete transcripts of the corresponding genome RNAs and that in this respect they differ from the unpolyadenylated virus specific complementary RNAs obtained from infected cells. From the position of the untranscribed oligonucleotide in the virus RNA sequence and the ability or inability of the different transcripts to protect the 5' terminal nucleotide of virus RNAs against nuclease S1 digestion, it is concluded that whereas the unpolyadenylated cRNAs are complete transcripts, the polyadenylated messenger RNAs lack sequences complementary to the 5' end of the genome molecules.
TL;DR: It is demonstrated that repetitive and single copy sequences in the Achlya genome are arranged in a long-period interspersion pattern and it is difficult to propose a regulatory function for repeated DNA in this eukaryote.
Abstract: Experiments are described that characterize the organization of DNA sequences in the water mold Achlya bisexualis. These experiments demonstrate that repetitive and single copy sequences in the Achlya genome are arranged in a long-period interspersion pattern. Estimates of the spacing intervals between repetitive and single copy DNA indicate, however, that the interspersion pattern in Achlya is longer than has been previously reported in other eukaryotes. These data and measurements of structural gene expression in Achlya [Timberlake, W.E., Shumard, D. S. & Goldberg, R. B. (1977) Cell 10, 623-632] make it difficult to propose a regulatory function for repeated DNA in this eukaryote.