bluuebunny/crossref_metadata_2025 huggingface dataset:
Origin and Direction of Simian Virus 40 Deoxyribonucleic Acid Replication
Authors: Fareed George C. , Garon Claude F. , Salzman Norman P.
Published: January 2020

Double-branched, circular, replicating deoxyribonucleic acid (DNA) molecules of simian virus 40 (SV40) have been cleaved by the R
1
restriction endonuclease from
Escherichia coli.
This enzyme introduces one double-strand break in SV40 DNA, at a specific site. The site of cleavage in the replicating molecules was used in this study to position the origin and the two branch points. Radioactively labeled molecules fractionated according to their extent of replication were evaluated after cleavage by sedimentation analysis and electron microscopy. The results demonstrate that the R
1
cleavage site is 33% of the genome length from the origin of replication and that both branch points are growing points. These data indicate that SV40 DNA replication is bidirectional and confirm other reports which have shown a unique origin of replication.
Separation of the Herpesvirus Deoxyribonucleic Acid Duplex into Unique Fragments and Intact Strand on Sedimentation in Alkaline Gradients
Authors: Frenkel Niza , Roizman Bernard
Published: January 2020

Deoxyribonucleic acid (DNA) extracted from herpes simplex virions forms multiple partially overlapping bands upon denaturation and centrifugation in alkaline sucrose density gradients. The most rapidly sedimenting DNA corresponds to an intact strand 48 × 10
6
daltons in molecular weight. In this study, we analyzed the DNA fragments generated in alkaline sucrose gradients with respect to size and uniqueness of base sequences. The distribution of sedimentation constants of the various fragments obtained in numerous gradients showed that the fragments smaller than the whole strand fall into six distinct classes ranging in molecular weight from 10 × 10
6
to 39 × 10
6
daltons. Four types of DNA strands can be reconstructed from the whole strand and six fragments on the basis of their molecular weights. DNA from each of the bands self-hybridizes to a lower extent than unfractionated viral DNA, indicating that each of the bands preferentially contains sequences from one unique strand. The data permit reconstruction of four possible types of DNA duplexes differing in the positions of the strand interruptions. Analysis of viral DNA extracted from nuclei of cells labeled with
3
H-thymidine for intervals from 3 to 120 min showed that nascent DNA is invariably attached to small fragments and that the fragments become elongated only upon prolonged incubation of cells. The experiments suggest that viral DNA replication begins at numerous initiation sites along each strand and that the elongation beyond the size of the replication unit involves repair or ligation, or both. Since newly made DNA yields more fragments than viral DNA extracted from mature virions, it is suggested that the fragmentation of mature DNA on denaturation with alkali arises from incomplete processing of specific initiation sites. Comparison of viral DNA extracted from nuclei with that extracted from mature cytoplasmic virions in cells labeled for 120 min indicates that packaged DNA is not randomly selected from among the nuclear DNA population but rather represents DNA molecules which in alkaline gradients yield a minimal number of fragments.
Isolation and Characterization of a Lysogenic Strain of
Nocardia erythropolis
Authors: Crockett Jennifer K. , Brownell George H.
Published: January 2020

A stable phage-carrying strain of
Nocardia erythropolis
was isolated from an infection with the nocardiophage φEC. Growth of the strain in phage-specific antiserum for 48 hr produced cured organisms at a frequency of about 0.5%. Spontaneous curing, determined by serial single-colony isolations, was less than 0.4%. The strain could not be infected by phage φEC nor by a closely related phage, φC, although the cells were able to adsorb these phages. In cell populations, a frequency of 2.5 × 10
−4
cells spontaneously induced. The growth rate of the strain was comparable to that of the uninfected wild-type
N. erythropolis.
Ultraviolet irradiation or treatment with mitomycin C induced the strain to produce larger numbers of phage. It was concluded that the isolated strain was lysogenic.
Structural Proteins of Simian Virus 40: Phosphoproteins
Authors: Tan K. B. , Sokol F.
Published: January 2020

All five structural polypeptides of infectious simian virus 40 grown in African green monkey kidney cells were found to be phosphorylated. The polypeptides with the largest and smallest molecular weights are phosphorylated to a somewhat lower extent than the other polypeptides. The protein moiety of “empty” virus, which is essentially devoid of deoxyribonucleic acid, exhibited a degree of phosphorylation similar to that of infectious virus. In the major polypeptide (molecular weight: 49,000), the phosphate appears to be bound to the seryl or threonyl residues, or both. The nature of the phosphate-polypeptide bond in the other viral polypeptides remains obscure.
Latency of Human Measles Virus in Hamster Cells
Authors: Knight Paul , Duff Ronald , Rapp Fred
Published: January 2020

A latent system employing measles virus (Schwarz strain) was developed in hamster embryo fibroblasts (HEF). Measles virus-specific antigen was detected by immunofluorescence in 30 to 50% of HEF cells, and these cells released infectious virus when co-cultivated with a susceptible monkey cell line, BSC-1 cells. No infectious virus could be detected in the cells when measures were taken to exclude passage of viable latent cells onto the indicator BSC-1 cells. Infectious center assays demonstrated that about 1 in 10 of the latently infected cells in the population could release infectious virus. Infectious virus appeared within 6 hr after co-cultivation of the HEF cells with BSC-1 cells, as compared to 24 hr required for normal replication of measles virus in the BSC-1 cells. Furthermore, labeling of progeny virus ribonucleic acid (RNA) by using tritiated uridine, and inhibition of RNA or protein synthesis by 5-azacytidine or cycloheximide suggested that neither additional RNA nor protein synthesis is required after co-cultivation of the cells to effect early virus release. It can therefore be postulated that there is a block at a late step in virus replication in the latently infected hamster cells. The most obvious site would concern maturation of infectious virions at the cell membrane.
Transient Inhibition of Polyoma Virus Synthesis by Sendai Virus (Parainfluenza I) II. Mechanism of the Interference by Inactivated Virus
Authors: Smith Gary L. , Consigli Richard A.
Published: January 2020

The mechanism of the transient inhibition of polyoma virus synthesis by betapropiolactone-inactivated Sendai virus was studied. Polyoma virus early functions did not appear to be affected, although deoxyribonucleic acid (DNA) and structural protein synthesis were inhibited 60 and 35% respectively. The inhibition of macromolecular synthesis was not sufficient to account for the 90% inhibition of infectious progeny formation. Encapsidation of polyoma DNA into mature virions appears to be completely inhibited after superinfection by beta-propiolactone-inactivated Sendai virus. Ultraviolet irradiation of live or beta-propiolactone-inactivated Sendai virus preparations abolishes the interfering capacity, indicating that a functional Sendai virus ribonucleic acid molecule is the interfering component.
Temperature-Sensitive Mutants of Vesicular Stomatitis Virus: In Vitro Studies of Virion-Associated Polymerase
Authors: Cairns J. E. , Holloway A. F. , Cormack D. V.
Published: January 2020

The temperature dependence of the virion-associated polymerase activity of six temperature-sensitive (ts) mutants of vesicular stomatitis virus (tsW10, 11, 14, 16B, 28, and 29) has been examined in vitro and compared to the heat-resistant parent (HR). The polymerase of five of the mutants (tsW10, 11, 14, 16B, and 28) appears to be significantly more ts than that of HR. Because certain pairs of these five mutants can complement each other's in vitro polymerase activity, it appears that in vitro some components involved in the polymerase of one virion can be utilized by another virion. Examination of 19 revertants of tsW11 and tsW16B which had regained their ability to replicate at 38 C showed that their in vitro polymerase activity had also become less ts. Furthermore, it was found that the pairs of mutants which showed in vitro complementation of polymerase activity at 38 C were those which had shown complementation in yielding infectious progeny in mixedly infected cells. These two observations suggest that the ts behavior of the in vitro polymerase activity of the five mutants is related to their inability to replicate at the nonpermissive temperature.
Asymmetric Transcription of Bacteriophage Mu-1
Authors: Bade Ernesto G.
Published: January 2020

The deoxyribonucleic acid (DNA) of bacteriophage Mu-1 can be separated into its complementary strands by poly(U,G) binding and equilibrium centrifugation. DNA-ribonucleic acid (RNA) hybridizations in liquid show that more than 98% of “early” phage-specific RNA and over 96% of “late” messenger species bind to the heavy [poly(U,G)-binding] strand of Mu-1 DNA. A small (1.45%) but significant amount of late RNA binds to the light strand. The significance of this RNA fraction is discussed in connection with the peculiar structure of denatured and reannealed Mu-1 DNA.
Classification of Rhabdovirus Proteins: a Proposal
Authors: Wagner R. R. , Prevec L. , Brown F. , Summers D. F. , Sokol F. , MacLeod R.
Published: January 2020

A simple alphabetical classification is offered as a means to codify the proteins of rhabdoviruses, using vesicular stomatitis virus as the prototype.
Thymidine Triphosphate Nucleotidohydrolase and Deoxyuridylate Hydroxymethylase Induced by Mutants of
Bacillus subtilis
Bacteriophage SP82G
Authors: Price Alan R. , Dunham Linda F. , Walker Robert L.
Published: January 2020

Assays on extracts of
Bacillus subtilis
infected by temperature-sensitive mutants of bacteriophage SP82G indicate that thymidine triphosphate nucleotidohydrolase may not be an essential SP82G enzyme and that deoxyuridylate hydroxymethylase is an essential enzyme coded for by SP82G gene 2.
Gene Expression During the Development of
Bacillus subtilis
Bacteriophage φ29 II. Resolution of Viral-Specific Ribonucleic Acid Molecules
Authors: Loskutoff D. J. , Pène J. J.
Published: January 2020

The ribonucleic acid (RNA) specified by bacteriophage φ29 was isolated under conditions which minimized physical and enzymatic degradation, reduced aggregation, and enriched for completed molecules. This RNA was fractionated both by sedimentation through sucrose density gradients and electrophoresis through polyacrylamide gels to measure the size and relative amount of each component. Early RNA consisted of six components of molecular weight 0.75 × 10
6
, 0.44 × 10
6
, 0.37 × 10
6
, 0.25 × 10
6
, 0.09 × 10
6
, and 0.04 × 10
6
, accounting for 35% of the coding capacity of φ29 deoxyribonucleic acid (DNA). All of these components except the one at 0.44 × 10
6
were detected when infection occurred in the presence of chloramphenicol. Synthesis of the major early component (0.75 × 10
6
) ceased shortly after the onset of viral DNA synthesis. The other species of early RNA were synthesized throughout the latent period. Three additional components, 1.75 × 10
6
, 0.93 × 10
6
, and 0.07 × 10
6
, appear at late times. The two large RNAs may be polycistronic messenger RNAs corresponding to the seven viral capsid proteins.
Stimulation of Sendai Virion Transcriptase by Polyanions
Authors: Stone Henry O. , Kingsbury D. W.
Published: January 2020

Exogenous polyribonucleotides stimulated the ribonucleic acid (RNA) transcriptase in Sendai virions. Added yeast RNA, polyadenylic acid, or polycytidylic acid increased incorporation of
3
H-guanosine monophosphate as much as fivefold. The products of stimulated reactions were virus-specific as determined by hybridization with Sendai virion RNA, but they sedimented more slowly (13
s
) than the product of an unstimulated reaction (16
s
). The stimulating activity was nondialyzable and heat stable, but was abolished by alkaline hydrolysis. Nucleoside monophosphates, individually or in combination, were ineffective, confirming the requirement for a polymer. Among other substances tested for effects on Sendai virion transcriptase, polyaspartic acid and polyglutamic acid stimulated the enzyme; polyinosinic acid, polyuridylic acid, and polyamines had no effect; and dextran sulfate and polyvinyl sulfate were inhibitory.
Pasteurella pestis
Bacteriophage H and
Escherichia coli
Bacteriophage φII Are Nearly Identical
Authors: Brunovskis Ilze , Hyman Richard W. , Summers William C.
Published: January 2020

Electron microscopy examination of φII-H deoxyribonucleic acid heteroduplexes, together with polyacrylamide gel electrophoretic analyses of phage ribonucleic acid species and proteins labeled in φII or H-infected cells, demonstrates that
Pasteurella pestis
phage H is nearly identical to coliphage φII.
Structural Organization of Murine Intracisternal A Particles
Authors: Wivel Nelson A. , Lueders Kira K. , Kuff Edward L.
Published: January 2020

Isolated murine intracisternal A particles have a distinctive set of structural properties as compared to the recognized oncogenic ribonucleic acid tumor viruses. A particles consist of two closely approximated concentric shells. The outer shell is largely, but not entirely, susceptible to treatment with detergents such as deoxycholate and Triton X-100. The inner shell is resistant to these agents and is stabilized against solubilization by sodium dodecyl sulfate as a result of disulfide bonding between its constituent proteins. The major A particle structural protein (molecular weight approximately 70,000) is contained in the inner shell. A protein component with a molecular weight of about 80,000 may be preferentially concentrated in sites of firm attachment between the inner and outer shells.
Resistance of Bacteriophage PBS2 Infection to 6-(
p
-Hydroxyphenylazo)-Uracil, an Inhibitor of
Bacillus subtilis
Deoxyribonucleic Acid Synthesis
Authors: Price Alan R. , Fogt Suzanne M.
Published: January 2020

6-(
p
-Hydroxyphenylazo)-uracil (HPUra), an inhibitor of semiconservative deoxyribonucleic acid (DNA) synthesis in
Bacillus subtilis
, does not prevent (but slightly reduces the rate of) replication of the uracil-containing DNA phage PBS2. Our observations are consistent with the hypothesis that all
B. subtilis
phages which are resistant to HPUra are able to induce a new DNA polymerase activity.
Bacteriophage T4 Head Maturation: Release of Progeny DNA from the Host Cell Membrane
Authors: Siegel Pamela J. , Schaechter Moselio
Published: January 2020

We have presented a new approach to studying bacteriophage T4 head maturation. Using a modified M-band technique, we have shown that progeny deoxyribonucleic acid (DNA) was synthesized on the host cell membrane throughout infection. This DNA was released from the membrane later in infection as the result of formation of the phage head; detachment of the DNA required the action of gene products 20, 21, 22, 23, 24, 31, 16, 17 and 49, known to be necessary for normal head formation. Gene products 2, 4, 50, 64, 65, 13 and 14, also involved in head morphogenesis were not required to detach progeny DNA from the membrane; the presence of the phage tail and tail fibers also was not required. DNA was released in the form of immature heads and initially was sensitive to deoxyribonuclease (DNase). Conversion to DNase resistance followed rapidly. The amount of phage precursors present at the time of DNA synthesis determined the time of onset and detachment rate of DNA from the M band as well as the kinetics by which the detached DNA become DNase resistant.
Synthesis of Bacteriophage-Coded Gene Products During Infection of
Escherichia coli
with Amber Mutants of T3 and T7 Defective in Gene 1
Authors: Issinger Olaf-Georg , Hausmann Rudolf
Published: January 2020

During nonpermissive infection by a T7 amber mutant in gene 1 (phage RNA polymerase-deficient), synthesis of the products of the phage genes 3 (endonuclease), 3, 5 (lysozyme), 5 (DNA polymerase), and 17 (serum blocking power) was shown to occur at about half the rate as during wild-type infection. This relatively high rate of expression of “late” genes (transcribed normally by the phage RNA polymerase) seems to be a general feature of all T7 mutants in gene 1 from our collection. In contrast, T3 gene 1 mutants and a T7 gene 1 mutant from another collection showed late protein synthesis at very reduced rates. Synthesis of the gene 3 endonuclease by T7 gene 1 mutants was very sensitive to the addition of rifampin 2 min after infection, conditions under which there was very little inhibition during wild-type infection. This supports the notion that late gene expression during nonpermissive infection by gene 1 mutants is dependent on the transcription of the T7 genome by the host RNA polymerase. In contrast to T3 gene 1 mutants, the T7 gene 1 mutants of our collection directed the synthesis of phage DNA during nonpermissive infection. This DNA accumulated as a material sedimenting faster than mature T7 DNA.
Identification of the Vesicular Stomatitis Virus Large Protein as a Unique Viral Protein
Authors: Stampfer Martha , Baltimore David
Published: January 2020

Previous studies have noted the existence of a 190,000-dalton vesicular stomatitis virus (VSV) protein called the large (L) protein. To determine whether this protein is a nonspecific aggregate, a precursor to the other VSV proteins, or a unique viral protein, its synthesis relative to the other VSV proteins was studied under conditions of inhibition of initiation of protein synthesis. Also, its tryptic peptides were compared to those of the other VSV proteins. In both cases the results were consistent with the identification of the large protein as a unique viral protein.
Purification By Oligo(dT)-Cellulose of Viral-Specific RNA from Sarcoma Virus-Transformed Mammalian Nonproducer Cells
Authors: Scolnick Edward M. , Benveniste Raoul , Parks Wade P.
Published: January 2020

Viral-specific RNA has been purified by oligo(dT)-cellulose chromatography from sarcoma virus-transformed nonproducer cells. This RNA comprises approximately 3% of the purified RNA, as judged by RNA-DNA hybridization.
Studies of Nondefective Adenovirus 2-Simian Virus 40 Hybrid Viruses. VI. Characterization of the DNA from Five Nondefective Hybrid Viruses
Authors: Henry Patrick H. , Schnipper Lowell E. , Samaha Richard J. , Crumpacker Clyde S. , Lewis Andrew M. , Levine Arthur S.
Published: January 2020

Certain biophysical characteristics of the DNA from each of the five nondefective adenovirus 2 (Ad2)-simian virus 40 (SV40) hybrid viruses (Ad2
+
ND
1
, Ad2
+
ND
2
, Ad2
+
ND
3
, Ad2
+
ND
4
, Ad2
+
ND
5
) have been determined. The guanine plus cytosine content varied from 55 to 57% and was not significantly different from that of nonhybrid Ad2 (56%), and the hybrid DNA molecules had mean molecular lengths which were similar to that of the standard, Ad2. The Ad2 and SV40 components of each hybrid were linked by alkali-resistant, presumably covalent bonds. The percentage of SV40 DNA in each hybrid virus was determined by hybridization with SV40 complementary RNA in a calibrated system. The results indicate that each hybrid virus DNA contains a different percentage of SV40 nucleotide sequences. The estimated size of the SV40 DNA component varies from 48,000 daltons for Ad2
+
ND
3
to 840,000 daltons for Ad2
+
ND
4
, the latter being equivalent to between one-fourth and one-third of the SV40 genome.
Preparation and Properties of an Inhibitory Extract from Frog Virus 3 Particles
Authors: Aubertin A.-M. , Hirth C. , Travo C. , Nonnenmacher H. , Kirn A.
Published: January 2020

The structural constituents of the frog virus 3 particle were solubilized by treatment with a nonionic detergent followed by the addition of a high salt concentration. This soluble viral extract (SVE) inhibits host nucleic acid synthesis. Its activity on RNA synthesis was studied in KB cells and found to be dependent on the presence of DEAE dextran. Inactivation of the inhibitory properties of SVE were obtained by trypsin digestion, treatment with urea, or heat denaturation. Neutralization of the activity of SVE was obtained by anti-frog virus 3 serum but not by anti-BHK serum. In vitro a complex may be formed between polynucleotides and the inhibitor indicating a possible mechanism for vivo inhibition.
Relationship of Reticuloendotheliosis Virus to the Avian Tumor Viruses: Nucleic Acid and Polypeptide Composition
Authors: Maldonado Reynaldo L. , Bose Henry R.
Published: January 2020

The RNA content and polypeptide composition of reticuloendotheliosis virus (REV) was compared to that of C-type RNA tumor viruses. Two RNA species with approximate sedimentation values of 64
S
and 4
S
were observed after sucrose gradient centrifugation of RNA extracted from purified REV. The high-molecular-weight RNA species of REV sedimented slightly faster than that of the Bryan strain of Rous sarcoma virus (RSV). Although these characteristics were consistent with those of other C-type RNA tumor viruses, significant differences were observed when the polypeptide composition of REV was compared with that of RSV possessing envelope determinants of Rous-associated virus RAV-2 and RAV-3. Five polypeptides of which two were glycosylated were resolved by polyacrylamide gel electrophoresis. The major nonglycosylated polypeptide of REV did not comigrate with that of RSV (RAV-2)-RSV(RAV-3). The majority of the group-specific antigen reactivity resides in this major nonglycosylated polypeptide of avian tumor viruses and comigrates when proteins of several avian tumor viruses are subjected to coelectrophoresis. This difference in the migration of the major polypeptide of REV and RSV(RAV-2)-RSV(RAV-3) may explain the absence of avian tumor virus group-specific antigen in REV.
Large-Molecular-Weight Precursors of Sindbis Virus Proteins
Authors: Schlesinger Milton J. , Schlesinger Sondra
Published: January 2020

Infection of chicken embryo fibroblasts with a temperature-sensitive mutant of Sindbis virus at the nonpermissive temperature leads to the accumulation of a large-molecular-weight protein. We have shown that this protein contains
14
C-arginine tryptic peptides present in the three virion proteins. We have also found that a slightly smaller protein which is detected in Sindbis-infected BHK cells contains the
14
C-arginine tryptic peptides of the two envelope proteins but not those of the capsid protein. Pulse-chase experiments indicate that the Sindbis virus protein in BHK cells is cleaved to the envelope proteins.
Function of T4D Structural Dihydrofolate Reductase in Bacteriophage Infection
Authors: Male Carolyn J. , Kozloff Lloyd M.
Published: January 2020

Various properties of the bacteriophage structural dihydrofolate reductase (DFR) have been examined to determine its function during phage infection. It has been found that a binding site for reduced nicotinamide adenine dinucleotide phosphate (NADPH), most likely on the DFR present in the phage tail plate, is required for phage viability. Attachment of adenosine diphosphoribose, an analogue of NADPH, to this site prevents phage adsorption and injection. This adenosine diphosphoribose inhibition can be competitively reversed by the addition of NADPH or oxidized nicotinamide adenine dinucleotide phosphate. It is suggested that, during phage infection, the host bacterial cell might leak compounds functionally similar to the pyridine nucleotides. These compounds have been shown to nonenzymatically change the conformation of the phage tail plate DFR which is apparently necessary for successful injection.
Effects of Furazolidone on the Infection of
Vibrio cholerae
by Bacteriophage φ149
Authors: Chatterjee S. N. , Maiti M.
Published: January 2020

Furazolidone in concentrations which had little effect on the growth of host organisms greatly reduced the yield of phage φ149 from the host
Vibrio cholerae
OGAWA 154. This phage was resistant to the in vitro action of the drug. The phage yield of infected bacteria depended significantly on the time of addition or withdrawal of the drug. The average burst size of the drug-treated and infected bacteria decreased exponentially with increase in drug concentration. The latent period of phage multiplication and also the eclipse period did not change significantly from the control values. A concentration of 0.05 μg of furazolidone per ml inhibited DNA synthesis by about 50% in phage-infected cells and only by about 18% in noninfected ones, relative to the respective controls. RNA and protein synthesis were affected by a much smaller degree both in infected and noninfected cells. Quantitative deduction of the length of furazolidone-treated cells from their phage adsorption characteristics and its agreement with previous electron microscopy data indicated that furazolidone did not affect the phage receptors.
Prophage Induction by High Temperature in Thermosensitive
dna
Mutants Lysogenic for Bacteriophage Lambda
Authors: Schuster H. , Beyersmann D. , Mikolajczyk M. , Schlicht M.
Published: January 2020

High-temperature treatment of thermosensitive
dna
mutants lysogenic for phage λ leads to prophage induction and release of phage (at the permissive temperature) in elongation-defective mutants of the genotypes
dnaB, dnaE
, and
dnaG.
In initiation-defective mutants no prophage induction occurs at 42 C in mutants of the genotype
dnaA
, whereas with a
dnaC
mutant as well as with strain HfrH 252 (map position not yet known) phages are released at 42 C. DNA degradation at the replication fork at 42 C is observed in all
dnaB
(λ) mutants tested, but not in mutants of the genotypes
dnaE
(λ) and
dnaG
(λ). Therefore, degradation of replication fork DNA is not a prerequisite for prophage induction.
Production of Viral mRNA in Adenovirus-Transformed Cells by the Post-Transcriptional Processing of Heterogeneous Nuclear RNA Containing Viral and Cell Sequences
Authors: Wall R. , Weber J. , Gage Z. , Darnell J. E.
Published: January 2020

Adenovirus 2-transformed cells contain virus-specific sequences which are covalently linked to cell-specific RNA sequences in heterogeneous nuclear RNA (HnRNA) molecules larger than 45
S
. Virus sequences are identified by hybridization to viral DNA, and the cell sequences are detected by hybridization to cellular DNA under conditions where hybridization only occurs to reiterated sites in cell DNA. Such large composite viral-cell HnRNA molecules presumably arise through the uninterrupted transcription of host sequences and integrated viral DNA. Adenovirus-specific polysomal RNA from these cells sediments as three discrete species at 16, 20, and 26
S
. These specific classes of viral mRNA do not contain rapidly hybridizing host-specific RNA sequences. Both virus-specific HnRNA and mRNA contain polyadenylic acid sequences since they bind to polyU columns at levels characteristics of other polyA-terminated HnRNA and mRNA. Thus, the discrete species of virus-specific mRNA in adenovirus 2 transformed cells appear to be derived from high-molecular-weight virus-specific HnRNA through a series of post-transcriptional modifications involving polyA addition. Subsequently the HnRNA is cleaved so that the cell-specific RNA sequences that originate from the reiterated sites in cell DNA do not accompany the adenovirus mRNA to the cytoplasm. These events for the adenovirus-specific mRNA appear, therefore, to be similar to the stages in the biogenesis of the majority of mRNA in eukaryotic cells.
Cytomegalovirus Replication in Cells Pretreated with 5-Iodo-2′-Deoxyuridine
Authors: Jeor Stephen St. , Rapp Fred
Published: January 2020

The replication of human cytomegalovirus (CMV) in cells pretreated with 5-iodo-2′-deoxyuridine (IUdR) was studied. Pretreatment of cells with IUdR enhanced several parameters of virus replication. Virus grown in drug-treated cells exhibited a shorter eclipse period and the cells produced more infectious virus sooner than did untreated cells. There was an approximate fivefold increase in virus yield per cell in the drug-treated samples when compared to control cultures. The time required for plaque development was shortened by 6 days in drug-treated cultures. Pretreatment of cells with IUdR also increased plaquing efficiency of the virus by approximately 10-fold. The enhancement of virus replication by IUdR was further demonstrated by varying the multiplicity of infection. In a 7-day period there was a 100-fold increase in sensitivity of the cultures for virus detection when the cells had been previously exposed to IUdR. The data presented indicate the possibility that IUdR interferes with the production of a cellular product inhibitory for CMV replication.
Studies on the Topography of Reovirus and Bluetongue Virus Capsid Proteins
Authors: Martin Scott A. , Pett Donald M. , Zweerink Hand J.
Published: January 2020

Protein labeling experiments confirm the surface location of proteins 2 and 5 in bluetongue virus, and proteins σ3 and μ2 in reovirus. Lambda 2 is the major surface component of the reovirus core, and proteins 1, 3, and 4 appear to be the outer components of the bluetongue virus subviral particle.
Adaptation of Plaque Assay Methods to the in Vitro Quantitation of the Radiation Leukemia Virus
Authors: Niwa O. , Declève A. , Lieberman M. , Kaplan H. S.
Published: January 2020

A modification of the XC cell procedure for murine leukemia virus assay which yields quantitative data over a wide range of virus concentrations is described. By using serial passage of infected cell cultures and reversal of the plating sequence in the XC procedure, titers of radiation leukemia virus (RadLV) were obtained which were about 10-fold higher than those found by using the conventional assay. By using the modified procedure, it was observed that, even at high multiplicities of infection, less than 10% of the cells function as infective centers, although the proportion increases with serial passage. It was also observed that exposure of infected cells to UV light, which is commonly used to make plaques more visible in the conventional XC cell test, inhibits plaque formation in the RadLV system. Substitution of X irradiation for UV exposure improved plaque visibility without loss of sensitivity.
Inactivation of T4D Bacteriophage by Antiserum Against Bacteriophage Dihydrofolate Reductase
Authors: Mathews C. K. , Crosby L. K. , Kozloff L. M.
Published: January 2020

Antiserum was prepared against highly purified T4D bacteriophage-induced dihydrofolate reductase (DFR). This serum not only inactivated the enzyme but also inactivated all strains of T4D examined. T6 was inactivated to a lesser extent, and T2L, T2H, and T5 were unaffected by the antiserum. The phage-killing power of the serum could be blocked by prior incubation with partially purified T4D dfr obtained from host cells unable to make phage structural proteins. These observations confirm earlier results that the phage dfr is a structural component of the phage particle, and they offer new evidence on the manner in which this enzyme in incorporated into the tail structure.
Variants of Simian Virus 40-Transformed 3T3 Cells That Are Resistant to Concanavalin A
Authors: Ozanne Brad
Published: January 2020

By treating populations of simian virus 40 (SV40)-transformed 3T3 cells with concanavalin A, variants have been isolated which are resistant to the killing action of the lectin. The variants (i) resemble 3T3 cells morphologically and in some of their growth characteristics; (ii) are not agglutinated by high concentrations of concanavalin A or wheat germ agglutinin, but can be rendered agglutinable by treatment with low concentrations of trypsin; (iii) bind the same number of concanavalin A molecules as 3T3 or SV3T3 cells; (iv) cannot be transformed by SV40 and are resistant to focus formation after infection with murine sarcoma virus; (v) contain SV40-specific T antigen and RNA and; (vi) yield wild-type SV40 virus after heterokaryon formation with BS-C-1 cells.
Oncogenic Transformation of Hamster Embryo Cells After Exposure to Inactivated Herpes Simplex Virus Type 1
Authors: Duff Ronald , Rapp Fred
Published: January 2020

The in vitro transformation of hamster embryo fibroblasts by herpes simplex virus type 1 (HSV-1) after exposure of the virus to UV irradiation is described. Cell transformation was induced by 2 out of 12 strains of HSV-1 that were tested for transforming potential. Cells transformed by the KOS strain of HSV-1 were not oncogenic when injected into newborn Syrian hamsters. However, cells transformed by HSV-1 strain 14-012 induced tumors in 47% of the newborn hamsters injected. HSV-specific antigens were found in the cytoplasm of cells transformed by both virus strains. Sera from tumor-bearing hamsters contained HSV-1- and HSV-2-neutralizing antibodies as well as antibodies which reacted specifically with HSV antigens by the indirect immunofluorescence technique. Hamster oncornavirus antigens were not detected by immunofluorescence methods. These observations represent the first evidence of the oncogenic potential of HSV-1.
Specificity of Formation of Complexes Between Coat Protein and Bacteriophage f2 RNA
Authors: Chroboczek Jadwiga , Pietrzak Maciej , Zagórski Wlodzimierz
Published: January 2020

The specificity of formation of phage f2 RNA-protein complexes was studied. Complex I contains up to 8 mol of coat protein per 1 mol of RNA. Its formation proceeds equally well in medium (i) without magnesium ions, (ii) containing magnesium ions, (iii) containing 4 mM EDTA, and (iv) at temperatures from 0 to 45 C. Complex II contains up to 200 mol of coat protein per 1 mol of RNA. Its formation is inhibited by the presence of magnesium ions in medium. Formaldehyde- or methoxyamine-treated f2 RNA in which only exposed bases were modified showed a normal pattern of complex II formation, whereas formation of complex I was inhibited or abolished. We conclude that complex I formation involves the interaction between coat protein and specific region of exposed bases in RNA. A possible site of attachment of coat protein is discussed.
Host-Mediated Repair of Discontinuities in DNA From T4 Bacteriophage
Authors: Carlson K. , Lorkiewicz Z. K. , Kozinski A. W.
Published: January 2020

Discontinuities of T4 DNA which are caused by excision of UV-damaged areas, by decay of
32
P atoms, or which are present in DNA from rII
-
lig
am
-
phage produced in a host nonpermissive for amber mutants are all repaired by bacterial enzymes after infection in the presence of chloramphenicol.
Escherichia coli
DNA polymerase I participates in the host-mediated repair, but an approximately 20-fold variation in the levels of host polynucleotide ligase does not affect either the kinetics or the extent of repair observed. Upon removal of chloramphenicol, host-repaired DNA from UV-irradiated phage undergoes a secondary cycle of breakage, which ultimately results in solubilization of most of the phage DNA. If the cells are co-infected with nonirradiated helper phage, the secondary breaks are repaired and the continuity of the polynucleotide chain is restored. The close coincidence in the extent of primary and secondary breakage suggests that phage-coded enzymes recognize and excise areas improperly repaired by the host. In contrast to host-mediated repair, repair mediated by rescuing phage probably restored functionality to the damaged DNA.
Characterization of the Low-Molecular-Weight RNAs Associated with the 70
S
RNA of Rous Sarcoma Virus
Authors: Faras A. J. , Garapin A. C. , Levinson W. E. , Bishop J. M. , Goodman H. M.
Published: January 2020

Two low-molecular-weight RNAs are associated with the 70
S
RNA complex of Rous sarcoma virus: a previously described 4
S
RNA and a newly identified 5
S
RNA. The 4
S
RNA constitutes 3 to 4% of the 70
S
RNA complex or the equivalent of 12 to 20 molecules per 70
S
RNA. It exhibits a number of structural properties characteristic of transfer RNA as revealed by two-dimensional electrophoresis of oligonucleotides obtained from a T1 ribonuclease digest of the 4
S
RNA species. The 5
S
RNA is approximately 120 nucleotides in length, constitutes 1% of the 70
S
RNA complex or the equivalent of 3 to 4 molecules per molecules of 70
S
RNA, and is identical in nucleotide composition and structure to 5
S
RNA from uninfected chicken embryo fibroblasts. Melting studies indicate that the 5
S
RNA is released from the 70
S
RNA complex at the same temperature required to dissociate 70
S
RNA into its constituent 35
S
subunits. In contrast, greater than 80% of the 4
S
RNA is released from 70
S
RNA prior to its conversion into subunits. The possible biological significance of these 70
S
-associated RNAs is discussed.
Genetic Control of Capsid Length in Bacteriophage T4 I. Isolation and Preliminary Description of Four New Mutants
Authors: Doermann A. H. , Eiserling F. A. , Boehner Linde
Published: January 2020

Four new mutants are described whose phenotypic expression affects the length of the head of bacteriophage T4D. All mutants produce some phenotypically normal phage particles. Mutant
pt21-34
also produces at least two size classes of phage particle which have heads that are shorter than normal. The other three mutants,
ptg19-2, ptg19-80
, and
ptg191
, produce, in addition to phages with normal and with shorter-than-normal heads, giant phages with heads from 1.5 to at least 10 times the normal length. All mutations are clustered near gene 23. Giant phage particles have the following properties: they are infectious and contain and inject multiple genomes as a single continuous bihelical DNA molecule of greater-than-unit length. Their frequency, relative to the total plaque-former population, increases late in the infectious cycle. They have a normal diameter, variable length, and a buoyant density range in CsCl from equal to slightly greater than that of normal phage. The arrangement of capsomers is visible in the capsids, which are composed of cleaved gene 23 protein.
Incorporation of Labeled Precursors into the RNA and Proteins of Lactic Dehydrogenase Virus
Authors: Niwa Akira , Yamazaki Shudo , Bader John , Notkins Abner Louis
Published: January 2020

Lactic dehydrogenase virus was grown in primary mouse embryo cells and labeled with
3
H-uridine and
3
H-amino acids. Concentrated and purified virus was banded by isopycnic centrifugation in sucrose gradients, and infectivity and radioactivity were found to correspond at a density of 1.17 g/cm
3
. The extracted viral RNA was resolved by electrophoresis in polyacrylamide-agarose mixed gels, and the mol wt was estimated to be 6.0 × 10
6
.
Effect of Nalidixic Acid on PBS2 Bacteriophage Infection of
Bacillus subtilis
Authors: Price Alan R. , Fogt Suzanne M.
Published: January 2020

Infection of
Bacillus subtilis
by PBS2 phage, whose DNA contains uracil instead of thymine, is relatively unaffected by low concentrations of nalidixic acid which severely inhibit
B. subtilis
DNA synthesis. High concentrations of nalidixic acid do inhibit PBS2 DNA synthesis, but more severely reduce the burst size of PBS2 infections. Hydroxyurea blocks PBS2 DNA synthesis, preventing progeny phage production.
Sedimentation Changes of L Cells in a Density Gradient Early After Infection with Vaccinia Virus
Authors: Ball Frederick R. , Medzon Edward L.
Published: January 2020

By 2 h postinfection, LM cells infected with vaccinia virus show a shift in their distribution when separated on a Ficoll density gradient. This shift is dependent on both time and the multiplicity of infection and is due, at least in part, to an increase in cell size. Those cells which do shift in position in the gradient represent infected members of the population. Physical changes induced in virus-infected cells can be utilized for studying early events in virus replication.
Gel Electrophoresis of Avian Leukosis and Sarcoma Viral RNA in Formamide: Comparison with Other Viral and Cellular RNA Species
Authors: Duesberg Peter H. , Vogt Peter K.
Published: January 2020

Class
a
and class
b
30 to 40
S
RNA subunits obtained by heat dissociation from the 60 to 70
S
RNA complex of avian tumor viruses were compared with several RNA standards by electrophoresis in formamide-polyacrylamide gels. Class
a
RNA was found to have a lower electrophoretic mobility and hence probably a higher molecular weight than class
b
RNA. The absolute molecular weight of class
a
and
b
RNA could not be determined with accuracy, because the relationship between logarithm of molecular weight and mobility of the RNA standards was not linear. The size of class
a
RNA fell into the range of 2.4 × 10
6
to 3.4 × 10
6
daltons and that of class
b
into the range of 2.2 × 10
6
to 2.9 × 10
6
daltons, depending on the standards used. The possible biological significance of this difference is discussed.
Hydroxyurea-Induced Accumulation of Short Fragments During Polyoma DNA Replication I. Characterization of Fragments
Authors: Magnusson Göran
Published: January 2020

Hydroxyurea treatment of 3T6 mouse fibroblast cells infected with polyoma virus resulted within 15 min in more than a 20-fold reduction of the rate of both viral and cellular DNA synthesis. After the initial rapid inhibition, the rate of DNA synthesis remained essentially constant for at least 2 h. In the inhibited cells viral DNA accumulated as short chains with a sedimentation coefficient of about 4
S
(hydroxyurea fragments). A variable proportion of these fragments was released from the template strands when the viral DNA was extracted by the Hirt procedure. Reannealing experiments demonstrated that hydroxyurea fragments were polyoma-specific and probably synthesized on both parental strands at the replication forks.
Hydroxyurea-Induced Accumulation of Short Fragments During Polyoma DNA Replication II. Behavior During Incubation of Isolated Nuclei
Authors: Magnusson Göran
Published: January 2020

The synthesis of polyoma DNA was studied in isolated nuclei from hydroxyurea-inhibited 3T6 cells infected with polyoma virus. During incubation of nuclei under conditions suitable for polyoma DNA synthesis in vitro, the short DNA fragments with a sedimentation coefficient of 4
S
formed in vivo (hydroxyurea fragments) became associated with preformed, replicating DNA strands. Centrifugation in dye-buoyant density gradients showed that the fragments formed part of the structure of the replicative intermediate of polyoma DNA. The proportion of “young” replicative intermediates was larger after hydroxyurea inhibition than in uninhibited controls. Hydroxyurea fragments appear to be closely related to the 4
S
fragments formed as normal intermediates during discontinuous synthesis of polyoma DNA.
Growth of Pseudotypes of Vesicular Stomatitis Virus with N-Tropic Murine Leukemia Virus Coats in Cells Resistant to N-Tropic Viruses
Authors: Huang Alice S. , Besmer Peter , Chu Louise , Baltimore David
Published: January 2020

Formation of pseudotypes between murine RNA tumor viruses and vesicular stomatitis virus (VSV) has been confirmed. Pseudotypes of VSV genomes coated by the surface envelope from an N-tropic tumor virus grew equally well in cells homozygous for either the

Fv-1
n

or

Fv-1
b

alleles. Therefore, the product of the
Fv-1
locus, which restricts growth of murine RNA tumor viruses, must act on an intracellular aspect of tumor virus replication, a step after attachment and penetration.
Transfection of
Escherichia coli
Spheroplasts II. Relative Infectivity of Native, Denatured, and Renatured Lambda, T7, T5, T4, and P22 Bacteriophage DNAs
Authors: Lawhorne Larry , Kleber Ingrid , Mitchell Charles , Benzinger Rolf
Published: January 2020

The change of infectivity of phage DNAs after heat and alkali denaturation (and renaturation) was measured. T7 phage DNA infectivity increased 4- to 20-fold after denaturation and decreased to the native level after renaturation. Both the heavy and the light single strand of T7 phage DNA were about five times as infective as native T7 DNA. T4 and P22 phage DNA infectivity increased 4- to 20-fold after denaturation and increased another 10- to 20-fold after renaturation. These data, combined with other authors' results on the relative infectivity of various forms of φX174 and lambda DNAs give the following consistent pattern of relative infectivity. Covalently closed circular double-stranded DNA, nicked circular double-stranded DNA, and double-stranded DNA with cohesive ends are all equally infective and also most highly infectious for
Escherichia coli
lysozyme-EDTA spheroplasts; linear or circular single-stranded DNAs are about 1/5 to 1/20 as infective; double-stranded DNAs are only 1/100 as infective. Two exceptions to this pattern were noted: lambda phage DNA lost more than 99% of its infectivity after alkaline denaturation; this infectivity could be fully recovered after renaturation. This behavior can be explained by the special role of the cohesive ends of the phage DNA. T5 phage DNA sometimes showed a transient increase in infectivity at temperatures below the completion of the hyperchròmic shift; at higher temperatures, the infectivity was completely destroyed. T5 DNA denatured in alkali lost more than 99.9% of its infectivity; upon renaturation, infectivity was sometimes recovered. This behavior is interpreted in terms of the model of T5 phage DNA structure proposed by Bujard (1969). The results of the denaturation and renaturation experiments show higher efficiencies of transfection for the following phage DNAs (free of single-strand breaks): T4 renatured DNA at 10
−3
instead of 10
−5
for native DNA; renatured P22 DNA at 3 × 10
−7
instead of 3 × 10
−9
for native DNA; and denatured T7 DNA at 3 × 10
−6
instead of 3 × 10
−7
for native DNA.
Reassortment of Simian Virus 40 DNA During Serial Undiluted Passage
Authors: Martin Malcolm A. , Gelb Lawrence D. , Fareed George C. , Milstien Julie B.
Published: January 2020

Alterations occur in the supercoiled form of viral DNA after the serial undiluted passaging of simian virus (SV) 40. We have identified a portion of the viral genome which is amplified during this process. These SV40 DNA sequences represent about 30% of the viral genetic information and are present in a reiterated form in twisted circular molecules prepared from purified virions. In addition, reiterated and unique green monkey DNA sequences are incorporated into supercoiled viral DNA. The cellular DNA appears to be inserted at numerous locations in the DNA I molecules.
Mechanism of Replication of Single-Stranded φX174 DNA VII. Circularization of the Progeny Viral Strand
Authors: Iwaya Makoto , Eisenberg Shlomo , Bartok Katalina , Denhardt David T.
Published: January 2020

Linear φX174 single-stranded DNA can be isolated from φX phage particles produced under various conditions. About half of the linear strands have a dGMP residue at the 5′ end, the remaining have roughly comparable amounts of dCMP, dTMP, and dAMP. The linear strands can be converted to covalently closed circular molecules by polynucleotide ligase, but only after they have been incubated with T4 DNA polymerase and deoxynucleoside triphosphates. Experiments with endonuclease R, the restriction enzyme from
Haemophilus influenzae
, indicated that the nucleotides incorporated into the DNA during this reaction were found predominantly in a limited region of the genome. The results suggest that the normal intermediate in single-stranded φX174 DNA synthesis may be a single-stranded linear molecule which is shorter than unit length and is intrinsically capable of circularization.