bluuebunny/crossref_metadata_2025 huggingface dataset:
Lysis and Lysogenization of Groups A, C, and G Streptococci by a Transducing Bacteriophage Induced from a Group G
Streptococcus
Authors: Colón Alba E. , Cole Roger M. , Leonard Carmen G.
Published: January 2020

A temperate bacteriophage, designated GT-234, was isolated from a group G
Streptococcus
after ultraviolet irradiation. After several single-plaque passages in a group G indicator strain, this phage formed plaques in 3 of 14 group A strains, in 3 of 15 group C strains, and in 4 of 13 group G strains—but not in some representatives of several other serogroups. After propagation in each of the sensitive strains, the progeny from each was shown to be the same phage by (i) adsorption and plaque formation in each of the other groups, (ii) lysogenization in each of the other groups, (iii) high titers on infection of each serogroup, regardless of the group of propagating strain, and (iv) neutralization of infection in each of the other groups by antiserum against the phage propagated in group G. Phage GT-234 is serologically related to virulent group A phage A25, from which it is morphologically indistinguishable. Like A25, it is a transducing phage. Other studies showed that A25, as well as a group A temperate transducing phage (AT-298), could also infect strains of group C and G. These results indicate a need for reassessment of group specificity and phage receptors among streptococci of groups A, C, and G and raise possibilities for intergroup transduction.
Differential Effect of Phleomycin on the Infectivity of Poliovirus and Poliovirus-Induced Ribonucleic Acids
Authors: Koch Gebhard
Published: January 2020

The infectivity of intact poliovirus was not affected by exposure to the antibiotic phleomycin at concentrations as high as 200 μg/ml, whereas that of the singlestranded poliovirus ribonucleic acid (RNA) was inactivated to 99% by pretreatment of the RNA with phleomycin at a concentration of 2 μg/ml. The infectivity of double and multistranded RNA was 10 times less sensitive than that of singlestranded RNA to the action of this antibiotic. Preincubation of HeLa cells for 30 min with 10 to 50 μg of phleomycin reduced the sensitivity of the cells to infection by viral RNA and intact virus, indicating that phleomycin interferes with cellular functions necessary for virus replication. When phleomycin was added to cells at different times after infection with single- or double-stranded RNA, the highest inactivation of infective centers was observed immediately after infection. With time of incubation at 37 C, the infective centers became more resistant to the action of phleomycin.
Effect of Rifamycins and Related Antibiotics on the Deoxyribonucleic Acid-Dependent Ribonucleic Acid Polymerase of Vaccinia Virus Particles
Authors: Szilágyi J. F. , Pennington T. H.
Published: January 2020

A number of compounds related to rifampin which act as expected in the
Escherichia coli
system have been tested for their ability to inhibit the vaccinia particle deoxyribonucleic acid-dependent ribonucleic acid (RNA) polymerase in vitro. Some compounds are inactive even at concentrations of 500 μg/ml, others are able to produce partial inhibition, and others strongly inhibit the enzyme activity at 150 μg/ml or less. The inhibition, where present, operates immediately but appears to be at least partially reversible. At least one compound which is without effect against bacterial RNA polymerase is a potent inhibitor of the viral RNA polymerase. As the enzyme activity of rifampin-resistant mutants of vaccinia virus is inhibited to the same extent as that of the wild type, the observed in vitro effect on vaccinia virus RNA polymerase is not identical with the in vivo effect specifically directed against a vaccinia-specified protein.
Transfection of
Escherichia coli
and
Salmonella typhimurium
Spheroplasts: Host-Controlled Restriction of Infective Bacteriophage P22 Deoxyribonucleic Acid
Authors: Benzinger Rolf , Kleber Ingrid
Published: January 2020

Under proper conditions, one infective center was obtained for 3 × 10
8
molecules of P22 phage deoxyribonucleic acid (DNA) when lysozyme-ethylenediaminetetraacetic acid spheroplasts of
Escherichia coli
were transfected in the presence of 25 μg of protamine sulfate per ml. A 3- to 50-fold B-specific and K-specific
E. coli
restriction of the incoming P22 DNA was observed. When P22 DNA-infected
E. coli
spheroplasts were plated with infertile
r

LT

+
m

LT

+
Salmonella typhimurium
indicator, an additional 70-fold restriction was observed. In the presence of protamine sulfate, penicillin spheroplasts of
S. typhimurium
SB1330 could be transfected b P22 DNA with efficiencies sometimes approaching those obtained with the
E. coli
spheroplasts; thus, facilitation of transfection by protamine sulfate is not limited to
E. coli
or to lysozyme-ethylenediaminetetraacetic acid spheroplasts. The application of these results to studies of transfection among other genuses and to studies of in vitro host-controlled restriction and modification for the two loci in
S. typhimurium
and the one locus in
E. coli
is discussed.
Similar Effect of Rifampin and Other Rifamycin Derivatives on Vaccinia Virus Morphogenesis
Authors: Grimley Philip M. , Moss Bernard
Published: January 2020

Membrane-limited structures, resembling virus envelope precursors previously shown to form during the interruption of poxvirus assembly by rifampin, were now observed by electron microscopy in vaccinia-infected HeLa cells treated with a series of rifamycin derivatives. The active compounds
N
-demethyl rifampin, AF/DMI, and 3-formyl rifamycin SV lacked, respectively, a methyl group, the piperazine ring, and the hydrazone portion of rifampin. A vaccinia mutant selected only for resistance to rifampin was also resistant to the effect on morphogenesis produced by all of the rifamycin derivatives. We concluded that this antiviral effect was specific and was a property associated with the macrocyclic ring rather than the hydrazone-containing side chain of rifampin. In addition to their effects on vaccinia morphogenesis, 3-formyl rifamycin SV and AF/DMI had unusual cytotoxic effects.
T-Even Bacteriophage-Tolerant Mutants of
Escherichia coli
B II. Nucleic Acid Metabolism
Authors: Mathews Christopher K. , Hewlett Martinez J.
Published: January 2020

T-even bacteriophage-tolerant mutants are strains of
Escherichia coli
which can adsorb T-even phages but cannot support the growth of infective virus. Under some conditions, the infected cells are not killed. Mutant cells infected by phage T6 are able to carry out several metabolic functions associated with normal virus development, including arrest of bacterial nucleic acid and protein synthesis, incorporation of isotopic precursors into viral nucleic acids and proteins, synthesis of early enzymes of deoxyribonucleic acid (DNA) metabolism, formation of rapidly sedimenting DNA intermediates, and formation of normal levels of early and late messenger ribonucleic acid species. Phage are unable to mutate to forms capable of growth on these mutants. The nature of the biochemical alteration leading to tolerance is still unknown.
Effect of Rifampin on the Development of Ribonucleic Acid Bacteriophage Qβ
Authors: Passent Jadwiga , Kaesberg Paul
Published: January 2020

The drug rifampin, when added at the time of infection, inhibits synthesis of the phage Qβ. Both viral ribonucleic acids and viral proteins are made in nearly the same amount as in the absence of rifampin, but the rate of assembly into phage particles is low.
Interaction of
Pseudomonas
Bacteriophage 2 with the Slime Polysaccharide and Lipopolysaccharide of
Pseudomonas aeruginosa
Strain BI
Authors: Bartell Pasquale F. , Orr Thomas E. , Reese John F. , Imaeda Tamotsu
Published: January 2020

Purified slime polysaccharide B and lipopolysaccharide of
Pseudomonas aeruginosa
strain BI were shown to possess receptor-like properties in inactivating
Pseudomonas
phage 2, whereas lipoprotein and glycopeptide fractions were devoid of activity. On a weight basis, slime polysaccharide B was more effective than lipopolysaccharide in inactivating phage. The specificity of the reaction with slime polysaccharide B was indicated by the fact that slime polysaccharide A of
P. aeruginosa
strain EI failed to inactivate phage 2. Electron micrographs showed phage 2 in typical, tail-first position of attachment on intact cells of strain BI, slime polysaccharide B, and lipopolysaccharide. Tail fibers were discernible during phage attachment.
Inhibition of Mitosis and Macromolecular Synthesis in Rat Embryo Cells by Kilham Rat Virus
Authors: Tennant Raymond W.
Published: January 2020

The effects of Kilham rat virus multiplication were studied in cultured rat embryo cells to examine the mechanisms by which virus infection might be related to developmental defects in rats and hamsters. The virus was found to inhibit motosis and deoxyribonucleic acid (DNA) synthesis within 2 to 10 hr after infection. However, total ribonucleic acid synthesis was relatively unaffected until about 20 hr after infection, and total protein synthesis did not decline significantly until loss of viable cells was apparent in the cultures. No effect on chromosomes was detected. The effect of Kilham rat virus on DNA synthesis appears to be due to inhibition of macromolecular synthesis rather than to an inhibition of uptake of precursors into cells. The effect of the virus on mitosis may be an addition to the effect on DNA synthesis, since mitosis is inhibited even in cultures in which cells are able to divide at the time of infection and which have presumably completed DNA synthesis.
Heat Induction of Prophage φ105 in
Bacillus subtilis:
Replication of the Bacterial and Bacteriophage Genomes
Authors: Armentrout Richard W. , Rutberg Lars
Published: January 2020

A temperature-inducible mutant of temperate
Bacillus
bacteriophage φ105 was isolated and used to lysogenize a thymine-requiring strain of
Bacillus subtilis
168. Synthesis of phage and bacterial deoxyribonucleic acid (DNA) was studied by sucrose gradient centrifugation and density equilibrium centrifugation of DNA extracted from induced bacteria. The distribution of DNA in the gradients was measured by differential isotope and density labeling of DNA before and after induction and by measuring the biological activity of the DNA in genetic transformation, in rescue of phage markers, and in infectivity assays. At early times after induction, but after at least one round of replication, phage DNA remains associated with high-molecular-weight DNA, whereas, later in the infection, phage DNA is associated with material of decreasing molecular weight. Genetic linkage between phage and bacterial markers can be demonstrated in replicated DNA from induced cells. Prophage induction is shown to affect replication of the bacterial chromosome. The overall rate of replication of prelabeled bacterial DNA is identical in temperature-induced lysogenics and in “mock-induced” wild-type φ105 lysogenics. The rate of replication of the bacterial marker
phe-1
(and also of
nia-38
), located close to the prophage in direction of the terminus of the bacterial chromosome, is increased in induced cells, however, relative to other bacterial markers tested. In temperature-inducible lysogenics, where the prophage also carries a
ts
mutation which blocks phage DNA synthesis, replication of both phage and bacterial DNA stops after about 50% of the phage DNA has replicated once. The results of these experiments suggest that the prophage is not initially excised in induced cells, but rather it is specifically replicated in situ together with adjacent parts of the bacterial chromosome.
Structure of Replicating Simian Virus 40 Deoxyribonucleic Acid Molecules
Authors: Sebring E. D. , Kelly T. J. , Thoren M. M. , Salzman N. P.
Published: January 2020

Properties of replicating simian virus 40 (SV40) deoxyribonucleic acid (DNA) have been examined by sedimentation analysis and by direct observation during a lytic cycle of infection of African green monkey kidney cells. Two types of replicating DNA molecules were observed in the electron microscope. One was an open structure containing two branch points, three branches, and no free ends whose length measurements were consistent with those expected for replicating SV40 DNA molecules. A second species had the same features as the open structure, but in addition it contained a superhelix in the unreplicated portion of the molecule. Eighty to ninety per cent of the replicative intermediates (RI) were in this latter configuration, and length measurements of these molecules also were consistent with replicating SV40 DNA. Replicating DNA molecules with this configuration have not been described previously. RI, when examined in ethidium bromide-cesium chloride (EB-CsCl) isopycnic gradients, banded in a heterogeneous manner. A fraction of the RI banded at the same density as circular SV40 DNA containing one or more single-strand nicks (component II). The remaining radioactive RI banded at densities higher than that of component II, and material was present at all densities between that of supercoiled double-stranded DNA (component I) and component II. When RI that banded at different densities in EB-CsCl were examined in alkaline gradients, cosedimentation of parental DNA and newly replicated DNA did not occur. All newly replicated DNA sedimented more slowly than did intact single-stranded SV40 DNA, a finding that is inconsistent with the rolling circle model of DNA replication. An inverse correlation exists between the extent of replication of the SV40 DNA and the banding density in EB-CsCl. Under alkaline conditions, the parental DNA strands that were contained in the RI sedimented as covalently closed structures. The sedimentation rates in alkali of the covalently closed parental DNA decreased as replication progressed. Based on these observations, some possible models for replication of SV40 DNA are proposed.
Physical and Biochemical Properties of Progressive Pneumonia Virus
Authors: Stone Lawrence B. , Takemoto Kenneth K. , Martin Malcolm A.
Published: January 2020

The physical and biochemical characteristics of progressive pneumonia virus were found to be remarkably similar to those of the ribonucleic acid (RNA) tumor viruses. Significant findings included the presence of a 60 to 70
S
RNA genome, RNA-dependent deoxyribonucleic acid polymerase activity, and common morphological properties. This information correlates with previously reported biological observations and supports the provisional inclusion of enveloped RNA-containing “slow viruses” within the RNA tumor virus group.
Control of Gene Function in Bacteriophage T4
Authors: Sauerbier Walter , Schweiger Manfred , Herrlich Peter
Published: January 2020

Synthesis of early T4 protein, which is normally shut off at 10 min after infection, continues until lysis when host cells have been preinfected with T3 sam
+
. In host cells preinfected with T3 sam
−
, synthesis of early enzymes is shut off as normal. Thus,
S
-adenosylmethionine is required for the turnoff of early T4 functions (at least when host cells have been preinfected with T3).
Regulation of Protein Synthesis in HeLa Cells
Authors: Leibowitz R. , Penman S.
Published: January 2020

The mechanism of inhibition of host cell protein synthesis by poliovirus has been studied by examining the behavior of host polyribosomes and polyribosome-associated messenger ribonucleic acid (mRNA). Virus infection appears to result in a specific inhibition of the initiation of translation of host cell mRNA. The site of inhibition does not appear to be mRNA itself. Human cells respond to virus infection by producing a factor antagonistic to the virus inhibition which promotes the initiation of host mRNA translation. The production of the host factor is sensitive to actinomycin; however, the behavior of the host cell factor and that of host mRNA appear distinctly different.
Characterization of the Subunit Structure of the Ribonucleic Acid Genome of Influenza Virus
Authors: Lewandowski L. J. , Content J. , Leppla S. H.
Published: January 2020

Ribonucleic acid extracted from influenza virus was labeled at the 3′ termini with
3
H and analyzed by polyacrylamide gel electrophoresis. Influenza virus was found to contain a minimum of seven and possibly as many as 10 polynucleotide chains, most of which appear to terminate at the 3′ end in uridine.
Mechanism of the Arginine Requirement for Adenovirus Synthesis
Authors: Everitt Einar , Sundquist Bo , Philipson Lennart
Published: January 2020

The mechanism of the arginine requirement for adenovirus was studied in cultures of KB cells infected with adenovirus type 2. Macromolecular synthesis was found to be severely impaired in uninfected cells under complete arginine deprivation, whereas an arginine concentration of 50 μ
m
yielded a moderate and reversible inhibition of growth and nucleic acid synthesis. At this concentration, viral structural proteins were accumulated in excess although the virus yield was reduced more than 1,000-fold. The arginine-sensitive step appeared to occur early during the first 15 hr postinfection in the virus growth cycle. Virus-infected cells deprived of arginine to 50 μ
m
showed, when reversed, a 4- to 5-hr lag period before the increase in virus growth was observed. Analysis of the radioactive pattern of labeled virions synthesized after reversion showed that all polypeptides were synthesized after addition of arginine to the medium, and none of the virion-polypeptides which are revealed by gel electrophoresis appeared to be preferentially synthesized after arginine reversion. The excess pool of structural proteins formed during depletion appeared to a large extent to be unavailable for virus assembly.
6 (
p
-Hydroxyphenylazo)-Uracil: a Reversible, Selective Inhibitor of the Replication of Deoxyribonucleic Acid of Staphylococcal Bacteriophage P11-M15
Authors: Brown Neal C.
Published: January 2020

6(
p
-Hydroxyphenylazo)-uracil (HPUra), a selective inhibitor of the semiconservative replication of deoxyribonucleic acid (DNA) of gram-positive bacteria, was found to inhibit the replication of DNA of bacteriophage P11-M15, a virulent derivative of the temperate
Staphylococcus aureus
bacteriophage P11. At appropriate concentration, HPUra inhibited DNA synthesis by P11-M15-infected
S. aureus
immediately and completely, regardless of the stage of the lytic cycle at which infected cells were exposed to drug. The effect of HPUra was reversible since the capacity of inhibited, infected cells to replicate phage DNA and produce mature phage could be restored by removal of HPUra from incubation media. Concentrations of HPUra which completely inhibited the replication of P11-M15 in its drug-sensitive host did
not
inhibit the replication of this phage or its DNA in several drug-resistant host mutants. HPUra also did
not
inhibit the replication of two other serologically distinct, virulent staphylococcal bacteriophages, P1 and 44AHJD, in drug-sensitive hosts.
Spontaneous Degradation of Reovirus Capsid into Subunits
Authors: Amano Y. , Katagiri S. , Ishida N. , Watanabe Y.
Published: January 2020

When a plaque-purified strain of reovirus type 3 (Dearing strain) degraded during storage, electron micrographs of the degraded virion were made which clearly demonstrated the substructural components of the outer capsid.
Localization of Parental Deoxyribonucleic Acid from Superinfecting T4 Bacteriophage in
Escherichia coli
Authors: Anderson Carl W. , Williamson Joseph R. , Eigner Joseph
Published: January 2020

High-resolution autoradiography has been employed to localize the nonsolubilized but genetically excluded deoxyribonucleic acid (DNA) of T4 bacteriophage superinfecting endonuclease I-deficient
Escherichia coli.
This DNA was found to be associated with the cell envelope (this term is used here to include all cellular components peripheral to and including the cytoplasmic membrane); in contrast, T4 DNA in primary infected cells, like host DNA in uninfected
E. coli
, was found to be near the cell center. The envelope-associated DNA from super-infecting phage was not located on the outermost surface of the cell since it was insensitive to deoxyribonuclease added to the medium. These results suggest that DNA from superinfecting T-even phage is trapped within the cell envelope.
Genome of Sindbis Virus
Authors: Arif B. M. , Faulkner P.
Published: January 2020

32
P-labeled ribonucleic acid (RNA) from purified Sindbis virus was examined for the presence of hidden breaks. Viral RNA was treated with acid at
p
H 2.9 or with formaldehyde and was analyzed on sucrose gradients or by polyacrylamide gel electrophoresis. The sedimentation pattern and mobility on polyacrylamide gels of the 42
S
RNA was unaffected by heating and quick cooling and was not altered by denaturing agents such as dimethyl sulfoxide and urea. No evidence that Sindbis RNA is a polyaggregate of fragments was obtained. It is concluded that the genome consists of a continuous length of single-stranded polynucleotide.
Morphogenesis of Bacteriophage φ80: Identification of the Cistron 13 Product
Authors: Deeb Samir S.
Published: January 2020

An in vitro complementation reaction leading to the assembly of bacteriophage φ80 tails from component proteins is described. Tail assembly occurs when a lysate of any mutant in cistron 13 is mixed with a second lysate of a mutant in any of the other cistrons involved in tail formation. Lysates of mutants that are blocked in tail formation contain phage heads that can unite with free tails to form infective particles. The rate of the complementation reaction shows little dependence upon temperature, suggesting that the assembly depends largely upon the kinetic encounter of the interacting components. The tail component missing in cistron 13 mutant lysates was purified approximately 55-fold and shown to be, at least in part, a protein having a molecular weight of approximately 22,000. This protein was also released from highly purified infective φ80 particles after osmotic shock followed by heattreatment, suggesting that it most probably is an integral structural protein of the phage tail. Lysates of mutants of bacteriophage λ that are defective in tail formation were shown to contain a tail component identical with or similar to the φ80 cistron 13 product.
Virus-Induced Interference in Heterologously Infected HeLa Cells
Authors: Doyle M. , Holland J. J.
Published: January 2020

In doubly infected HeLa cells, poliovirus type 1 rapidly and completely dominates vesicular stomatitis virus (VSV) plaque-forming unit production. Poliovirus type 1 shuts off incorporation of amino acids into VSV-specific proteins within 2 hr after superinfection of cells already committed to massive synthesis of VSV proteins. However, poliovirus type 1 appears to have little, if any, direct effect upon incorporation of uridine into VSV-directed ribonucleic acid (RNA) synthesis. Poliovirus apparently interferes with VSV virion production only at the level of translation of viral messenger RNA, although it interferes with host cell macromolecular syntheses at the levels of translation and transcription.
Immunoelectrophoretic Analysis of Avian Ribonucleic Acid Tumor Virus Group-Specific Antigens
Authors: Bonar R. A. , Ishizaki R. , Beard J. W.
Published: January 2020

Tumors induced in pigeons by inoculation with the Schmidt-Ruppin strain of Rous sarcoma virus regressed after about 6 weeks. Sera from these pigeons, taken 8 weeks after inoculation, had complement-fixing group-specific antibody titers of 1:2 to 1:256. In immunoelectrophoresis with the pigeon serum, disrupted BAI strain A (myeloblastosis) avian tumor virus showed at least five precipitin arcs. The pattern of precipitin lines was dependent in part on the means used for virus disruption, and ethyl ether and nonionic detergents appeared to be both effective and relatively mild reagents. Immunoelectrophoretic comparison of pigeon serum with serum from a tumor-bearing hamster and that from virus-inoculated rabbits yielded similar, though not identical, results.
Use of Miracil D to Suppress Bacterial Ribonucleic Acid and Protein Synthesis During Bacteriophage MS2 Infection
Authors: Cramer Jane Harris , Sinsheimer Robert L.
Published: January 2020

Under certain culture conditions, Miracil (35 μg/ml) halts the growth of uninfected
Escherichia coli.
Cellular ribonucleic acid (RNA) synthesis is almost completely suppressed, whereas deoxyribonucleic acid and protein synthesis are inhibited to a lesser extent. When the drug is added to host bacteria prior to infection with bacteriophage MS2, the phage adsorb to the cells, but penetration of the viral RNA is inhibited. Penetration may be achieved without further viral development by infection in the presence of chloramphenicol. If the bacteria are infected with MS2 in the presence of chloramphenicol, subsequently washed to remove the chloramphenicol, and then treated with Miracil at any time between 0 and 20 min postinfection, a second viral function is inhibited and the yield of progeny phage is reduced. Addition of the drug after 20 min postinfection does not inhibit the infection process. When Miracil is present from early times in infection, only a limited synthesis of both double- and single-stranded virus-specific RNA is observed. The viral RNA species thus produced do not appear to differ from those made in the absence of the drug. A comparison of the activities of the viral RNA synthetase produced during the course of infection in the presence and in the absence of Miracil suggests that a possible cause of the inhibition is the synthesis of an unstable enzyme in the presence of the drug.
Relationship Between Organization of Mammary Tumors and the Ability of Tumor Cells to Replicate Mammary Tumor Virus and to Recognize Growth-Inhibitory Contact Signals In Vitro
Authors: McGrath Charles M. , Nandi S. , Young Lawrence
Published: January 2020

Mammary tumor virus (MTV) replication was confined primarily to cells organized as acini in intact mouse mammary glands. Primary mammary tumors maintained a high degree of acinar organization and cells therein continued to replicate MTV vegetatively. Nonacinar mammary cells, derived by serial transplantation of acinar tumor cells, no longer actively replicated MTV. This suggests that phenotypic differences exist among mammary epithelial cells in their ability to support virus replication, that a fundamental relationship exists between the organization of epithelium for secretion and active virus replication, and that this relationship is not altered as a primary consequence of neoplastic transformation. Mammary epithelial cells from pregnant, non-tumor-bearing, MTV-infected BALB/cfC3H mice or from acinar mammary tumors from a number of mouse strains were grown in primary monolayer cultures. Such cell cultures under the influence of insulin and cortisol exhibited the ability to organize into discrete three-dimensional structures called “domes.” MTV replication in such cultures took place primarily in cells within the organized domes. Cells cultured from nonacinar tumors did not exhibit any propensity to organize into domes, nor did they replicate MTV in primary culture. This suggests that the cell organizational requirement for MTV replication observed in vivo is conserved in primary culture. Dome formation is not an effect of virus replication, as cells from uninfected BALB/c animals organized into domes in culture without concomitant MTV replication. Growth-regulating signals, exerted between contiguous cells in cultures of non-MTV-infected mammary epithelium, were not modified by the occurrence of active virus replication nor as a direct consequence of neoplastic transformation. Cells derived from nontumor BALB/cfC3H glands and from spontaneous tumors exhibited cell growth kinetics, saturation densities, and deoxyribonucleic acid synthesis kinetics nearly identical to those of noninfected normal mammary epithelium in primary culture. Cell to cell growth regulatory signals were modified in cultures of nonalveolar tumor cells wherein evidence of overgrowth is documented.
Nonproductive Infection and Induction of Cellular Deoxyribonucleic Acid Synthesis by Bovine Adenovirus Type 3 in a Contact-Inhibited Mouse Cell Line
Authors: Tsukamoto K. , Sugino Y.
Published: January 2020

Bovine adenovirus type 3 (BAV-3), which has been reported to produce tumors in newborn hamsters, induced cellular deoxyribonucleic acid (DNA) synthesis in a contact-inhibited mouse kidney cell line (C3H2K). In this system, the virus did not multiply, whereas virus-specific tumor antigen (T antigen) was detected in nearly all cells. Replication of viral DNA could not be detected by DNA-DNA hybridization on membrane filters. The cellular DNA synthesis induced by BAV-3 did occur in the absence of added serum. Extent of induction of cellular DNA synthesis was closely correlated with the multiplicity of infection. Cells activated to synthesize DNA in the serum-free medium by the virus infection progressed to cell division without noticeable cell killing.
Deoxyribonucleic Acid Bacteriophage of
Methanomonas methylovora
Authors: Oki Toshikazu , Nishida Hiroshi , Ozaki Asaichiro
Published: January 2020

A new bacteriophage of low guanine plus cytosine (GC) content for
Methanomonas methylovora
has been isolated. Phage deoxyribonucleic acid contained 32 to 35% GC.
A Remeasurement of the Molecular Weights of T-Even Bacteriophage Substructural Proteins
Authors: Cummings Donald J.
Published: January 2020

T-even bacteriophage substructural proteins were studied by using discontinuous sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It was found that tail fibers are composed of two major proteins of 155,000 and 120,000 daltons molecular weight and four minor proteins of 51,000, 38,000, 27,000, and 23,000 daltons. Tail tubes were composed of one predominant protein of 18,500 daltons and one minor protein of 35,000 daltons molecular weight. Tubular polyheads obtained from a T4D amber mutant and by treatment of T4B-infected cells with L-canavanine were also examined, and no significant differences were noted in the molecular weight of the P23 protein.
Impairment of Host Cell Ribonucleic Acid Polymerase II After Infection with Frog Virus 3
Authors: Campadelli-Fiume Gabriella , Costanzo Franco , Mannini-Palenzona Anna , La Placa Michele
Published: January 2020

Evidence is presented that, in frog virus 3-infected BHK cells, inhibition of ribonucleic acid (RNA) synthesis is paralleled by a decreased activity of host cell RNA polymerase II, while the template ability of host cell nuclei and chromatin is unaffected.
Mechanism of the Antiviral Activity Resulting from Sequential Administration of Complementary Homopolyribonucleotides to Cell Cultures
Authors: De Clercq Erik , De Somer Pierre
Published: January 2020

The antiviral activity of the double-stranded complex poly(rI) · poly(rC) in cell culture was restored or even surpassed if the constituent homopolymers were administered separately. Poly(rI) primed the cells for the antiviral activity of poly(rC) and poly(rC) primed for poly(rI), but neither poly(rI) nor poly(rC) primed the cells for the antiviral activity of noncomplementary homopolynucleotides. The priming effect of poly(rI) was significantly reduced if the poly(rI)-primed cells were treated with either T
1
ribonuclease or diethylaminoethyl (DEAE)-dextran before addition of poly(rC), and the priming effect of poly(rC) was significantly reduced if the poly(rC)-primed cells were treated with either pancreatic ribonuclease or DEAE-dextran before addition of poly(rI).
3
H-labeled poly(rC) bound more rapidly to poly(rI)-treated cells than to control cells. Cell-associated poly(rC) was markedly more resistant to pancreatic ribonuclease treatment if the cells had been incubated with poly(rI) before exposure to poly(rC). Our results clearly indicate that poly(rI) and poly(rC) added successively to cell cultures do not act independently but reunite at the cellular level, most likely at the outer cell membrane.
Inhibitory Effect of Bacteriophage P22 Infection on Host Cell Deoxyribonuclease Activity
Authors: Israel Vance , Woodworth-Gutai Mary , Levine Myron
Published: January 2020

Infection of
Salmonella typhimurium
with phage P22 causes a decrease in the activity of host deoxyribonuclease which degrades single-stranded deoxyribonucleic acid (DNA). This decrease is reversed when the infecting phage is
P22c
+
; it is not reversed if the infecting phage kills the cell. The decrease does not occur in infections with
P22ts25.1
(which only adsorbs and injects DNA) or in infections of a lysogen by a nonvirulent phage. It does occur, however, after infections with other phages which are blocked in phage DNA synthesis. Inhibiting protein synthesis with chloramphenicol does not in itself cause the decrease in uninfected cells, but it does prevent infected cells from showing this effect.
Pattern of Protein Synthesis in Monkey Cells Infected by Simian Virus 40
Authors: Anderson Carl W. , Gesteland Raymond F.
Published: January 2020

After infection of several permanent monkey cell lines by simian virus 40 (SV40), four additional protein bands can be detected by simple sodium dodecyl sulfate-polyacrylamide gel electrophoresis of whole-cell extracts. These bands appear only after the onset of viral deoxyribonucleic acid (DNA) synthesis, and inhibitors of DNA synthesis prevent their appearance. Three of them correspond to three previously identified capsid components, VP1, VP2, and VP3. The fourth protein band, which does not correspond to a previously identified virion component, is induced by SV40 infection of CV-1 and BSC-1 cultures but not by infection of MA-134 cultures.
Endonuclease Activity Associated with Purified Simian Virus 40 Virions
Authors: Kaplan Joan C. , Wilbert Sharon M. , Black Paul H.
Published: January 2020

Purified simian virus 40 has associated with it an endonuclease activity which converts form I (double-stranded, circular) simian virus 40 deoxyribonucleic acid to a nicked form that sediments as a homogeneous peak in alkaline sucrose gradients. The enzyme is dependent on magnesium ions for activity and is completely inhibited by ethylenediaminetetraacetic acid (0.02
m
) or heat (80 C for 10 min). In tris(hydroxymethyl)aminomethane-hydrochloride buffer it exhibits optimal activity between
p
H 6.7 and 7.1 at 37 C. Gel electrophoretic analysis of purified, disrupted virus indicates the absence of detectable host cell protein contamination.
Composition and Size of Shope Fibroma Virus Deoxyribonucleic Acid
Authors: Jacquemont B. , Grange J. , Gazzolo L. , Richard M. H.
Published: January 2020

Deoxyribonucleic acid (DNA) extracted from purified virions of Shope fibroma virus (SFV) (by using DNA from
Microccocus lysodeikticus
as marker) had a buoyant density of 1.6996 ± 0.0003 g/ml), hence a guanine plus cytosine (G + C) content of 40.4 ± 0.3%, which is close to the G + C content of the DNA of susceptible rabbit cells (40.9 ± 0.4%) and different from that of vaccinia virus DNA (35.5 ± 0.4%). For the determination of the molecular weight of DNA, SFV and vaccinia purified virions, treated with Pronase and detergent, were cosedimented in sucrose density gradients. Results showed that SFV-DNA has a molecular weight of about 153 × 10
6
daltons. By electron microscopy, only one molecule corresponding to this value was observed (its length was 80.3 μm). The others had a median size of 49.8 μm ± 0.9.
Organization of Gene Function in
Bacillus subtilis
Bacteriophage SP82G
Authors: Green D. MacDonald , Laman David
Published: January 2020

A generalized assessment of the functions of 26 genes of SP82G, a bacteriophage of
Bacillus subtilis
, has been made. The production of phage-specific deoxyribonucleic acid (DNA), DNA-filled phage heads, completed phage particles, phage-specific antigen, and developmental aberrations has been examined in lysates of temperature-sensitive mutants grown under selective conditions. The genes show a tendency to occur on the genome in three groups of related function: genes involved with DNA synthesis, with tail synthesis, and with head synthesis.
Structure and Function of the Polypeptides in Simian Virus 40 I. Existence of Subviral Deoxynucleoprotein Complexes
Authors: Huang Eng-Shang , Estes Mary K. , Pagano Joseph S.
Published: January 2020

Velocity sedimentation analysis of simian virus 40 degraded in alkaline buffers,
p
H 10.5, yields two components: soluble protein containing the largest polypeptides, VP1 and VP2, of the virion, and a deoxynucleoprotein complex (DNP-I) containing the viral deoxyribonucleic acid (DNA) and the small polypeptides, VP4, 5, and 6, and all or part of VP3. Dissociation of DNP-I by equilibrium centrifugation in CsCl yields a complex (DNP-II) of the viral DNA and residual, tightly bound polypeptide; VP4, 5, and 6, but not VP3, are recovered after separation from DNP-II. Treatment of the virus with β-mercaptoethanol and iodination experiments suggest that VP1 and VP2 might exist as compact structures cross-linked with disulfide bonds, perhaps forming the capsid. VP4, 5, and 6 form a relatively stable complex with the viral DNA and are supposed to be the internal proteins. The location of VP3 is not well defined; at least a portion of it is tightly bound to the viral DNA.
Genome- and Community-Level Interaction Insights into Carbon Utilization and Element Cycling Functions of
Hydrothermarchaeota
in Hydrothermal Sediment
Authors: Zhou Zhichao , Liu Yang , Xu Wei , Pan Jie , Luo Zhu-Hua , Li Meng
Published: January 2020

This study provides comprehensive metabolic insights into the
Hydrothermarchaeota
from comparative genomics, evolution, and community-level perspectives. Members of the
Hydrothermarchaeota
synergistically participate in a wide range of carbon-utilizing and element cycling processes with other microorganisms in the community. We expand the current understanding of community interactions within the hydrothermal sediment and chimney, suggesting that microbial interactions based on sequential substrate metabolism are essential to nutrient and element cycling.
Primary Pancreatic lymphoma: a rare clinical entity
Authors: Dunphy Louise , Abbas Syed Hussain , Al Shoek Ihsan , Al-Salti Wassim
Published: January 2020

Primary pancreatic lymphoma is a rare clinical entity representing <0.5% of pancreatic cancers and 1% of extranodal lymphomas. Due to the paucity of cases described in the literature, its clinicopathological features, differential diagnosis, optimal therapy and outcomes are not well defined. As the clinical manifestations are often non-specific, it can create a diagnostic pitfall for the unwary physician. Preoperative distinction of adenocarcinoma and primary pancreatic lymphoma is critical since the management and prognosis of these malignancies are mutually exclusive. Due to its rarity, epidemiological studies have been difficult to conduct. Chemotherapy with R-CHOP (rituximab, cyclophosphamide, doxorubicin and vincristine) has proven to be effective. The authors present the case of a 52-year-old man with epigastric pain and obstructive jaundice. Further investigation with a CT of the abdomen and pelvis showed a low attenuation mass in the head of the pancreas measuring 35×25 mm, suspicious for malignancy. The mass involved the common bile duct distally causing moderate retrograde intrahepatic and extrahepatic biliary tree dilation of 14 mm. He underwent endoscopic retrograde cholangiopancreatography, sphincterotomy and insertion of a stent. Core biopsies confirmed the diagnosis of a high-grade B cell pancreas lymphoma. He started treatment with R-CHOP and prednisolone. Due to disease progression, he started treatment with DA-EPOCH-R (etoposide phosphate, prednisone, vincristine sulfate, cyclophosphamide, doxorubicin hydrochloride and rituximab). There was no clinical response, and treatment with RICE (rituximab, ifosfamide, carboplatin and etoposide) was initiated. He showed partial response and was under consideration for chimeric antigen receptor T cell therapy. He deteriorated clinically and succumbed to his disease 5 months following his initial presentation. This paper will provide an overview of the spectrum of haematological malignancies and describe useful features in distinguishing primary lymphoma of the pancreas from an adenocarcinoma, hence avoiding its surgical resection.
Spontaneous bowel perforation in the setting of colonic involvement with scleroderma
Authors: Stupalkowska Weronika , Mahler-Araujo Betania , Bennett John , Gourgiotis Stavros
Published: January 2020

Here we present a rare case of spontaneous colonic perforation in a middle-aged woman affected by systemic sclerosis (SSc). In spite of maximal medical support and prompt emergency laparotomy for source control the patient died due to multiorgan failure within 48 hours of admission. This case emphasises that although rarely, patients with scleroderma can present with colonic perforation which unfortunately due to their decreased physiological reserve, can lead to rapid and irreversible deterioration and subsequent death. It is therefore essential that clinicians faced with abdominal symptoms and signs in patients affected by SSc are able to quickly differentiate acute visceral perforation from benign causes.
Sexually transmitted infections in persons living with HIV infection and estimated HIV transmission risk: trends over time from the DC Cohort
Authors: Secco Alessandra Anna , Akselrod Hana , Czeresnia Jonathan , Levy Matthew , Byrne Morgan , Monroe Anne , Lucar Jose , Horberg Michael , Castel Amanda Derryck , Doshi Rupali , Rivasplata Heather , Squires Leah , Parenti David , Benator Debra
Published: January 2020

Objective

A rise in incidence of STIs has been noted in the USA and in the District of Columbia (DC). We aim to describe changes in incident STIs among persons in care for HIV in Washington, DC as well as trends in HIV viral load among those with incident STIs.

Methods

We conducted a retrospective DC Cohort analysis (n=7810) measuring STI incidence (syphilis, gonorrhoea and chlamydia) as well as incare viral load (ICVL) and percentage with all viral loads less than the limit of detection (%<LLOD) by year (2012–2016) among those with incident STIs.

Results

From 2012 to 2016, the incidence of STIs increased: chlamydia from 2.1 to 3.4 cases/100 person-years (p=0.0006), gonorrhoea from 2.1 to 4.0 (p<0.0001), syphilis from 1.7 to 2.6 (p=0.0042) and any STI episode from 5.3 to 8.8 (p<0.0001). STI incidence rates increased for those aged 18–34 (from 13.2 to 23.2 cases/100 person-years, p<0.0001), cisgender men (from 6.5 to 11.5, p<0.0001), non-Hispanic whites (from 8.6 to 16.1, p=0.0003) and men who have sex with men (from 9.3 to 15.7, p<0.0001). During 2012–2016, the ICVL among those with incident STIs improved from 108 to 19 copies/mL and %<LLOD from 23.6% to 55.1%. However, even in 2016, younger participants, cisgender and transgender women, non-Hispanic blacks and Hispanics had higher ICVLs and lower %<LLOD.

Conclusions

Rates of incident STIs rose among persons in care for HIV in Washington, DC, with improved but not optimal measures of HIV viral suppression. These findings inform focused interventions towards preventing STI transmission and ending the HIV epidemic.
Anal dysplasia and HIV shedding in ART-treated men
Authors: Choi Yoojin , Salit Irving , Grech Sarah , Sano Marie , Weiss Edward , Kovacs Colin , Paquette Rachelle , Claudio Marian , Gibbons Suzanne , Severini Alberto , Kaul Rupert
Published: January 2020

Objectives

Anal human papillomavirus (HPV) infection is highly prevalent among men who have sex with men (MSM). HPV-associated anal dysplasia has been linked with anal HIV RNA shedding despite antiretroviral therapy (ART). Since mucosal HIV levels are a key determinant of sexual transmission of the virus, this would have important public health implications. Therefore, we assessed the association between anal dysplasia and HIV shedding in ART-treated MSM from Toronto, Canada.

Methods

In 54 HIV-infected men on effective ART, we assessed anal HIV RNA shedding by PCR, HPV infection by microsphere-based genotyping and anal dysplasia by high-resolution anoscopy. All participants were enrolled between May 2017 and October 2018.

Results

The median duration of ART at the time of study enrolment was 18 years, with most participants being on an integrase inhibitor-based ART regimen. Low-level anal HIV RNA shedding was present in 15/54 (27.8%) participants. Neither the detection of shedding nor the level of HIV RNA was associated with anal dysplasia, HPV infection or antiretroviral regimen.

Conclusions

HPV-associated anal dysplasia was not associated with anal HIV RNA shedding in this relatively small cohort of men on effective ART. While anal HIV RNA was detected more often than anticipated, shedding was low level and unlikely to cause HIV transmission. However, the immunological drivers of anal HIV RNA shedding in ART-treated individuals may merit further study.
Prediction of perforation velocity of hard missile impacts on reinforced concrete wall panels
Authors: Lulec Andac , Sadeghian Vahid , Vecchio Frank J.
Published: January 2020

This study reviews and compares the most commonly used models for computing the local effects of hard missile impacts. The accuracies of the models in predicting perforation velocity are evaluated using a dataset of 95 impact tests collected from the literature. It is found that the majority of the models are unable to accurately predict perforation velocity or have a limited application range because of their empirical nature. To address these limitations, a semi-analytical model based on the Modified Compression Field Theory and the principle of work and energy is proposed. Unlike most existing models, the proposed model is capable of considering the influence of in-plane and shear reinforcement. The performance of the proposed model is assessed against experimental results obtained from the compiled dataset as well as other existing models.
Novel laser-plasma TeV electron-positron linear colliders
Authors: Nakajima Kazuhisa , Wheeler Jonathan , Mourou Gérard , Tajima Toshiki
Published: January 2020

TeV center-of-mass energy electron-positron linear colliders comprising seamlessly staged capillary laser-plasma accelerators are presented. A moderate intensity laser pulse coupled with the single electromagnetic hybrid mode in a gas-filled capillary can generate plasma waves in the linear regime, where laser wakefields can accelerate equally focused electron and positron beams. In multiple stage capillary accelerators, a particle beam with respect to the laser wakefield can undergo consecutive acceleration up to TeV energies, associated with continuous transverse focusing in a beam size down to a nanometer level, being capable of a promising electron-positron linear collider with very high luminosities of the order of 10[Formula: see text] cm[Formula: see text]s[Formula: see text]. The transverse and longitudinal beam dynamics of beam particles in plasma wakefields with the effects of radiation reaction and multiple Coulomb scattering are investigated numerically to estimate the luminosities in beam-beam collisions with the effects of beamstrahlung radiation and bunch disruption.
Plasma based acceleration in crystals and nanostructures: Advantages and limitations
Authors: Lebedev V.
Published: January 2020

The paper presents a short overview of main physics phenomena which determine how the beam can be accelerated in plasma, crystal or a nanotube.