bluuebunny/crossref_metadata_2025 huggingface dataset:
Head Proteins from T-Even Bacteriophages II. Physical and Chemical Characterization
Authors: Forrest Gerald L. , Cummings Donald J.
Published: January 2020

Three classes of structural head proteins, having molecular weights of 43,000, 18,000, and 11,000 daltons, were isolated from the T-even bacteriophages and were characterized. Based on electrophoretic studies, the 43,000-dalton class contained one major protein and one (or two) minor components, the 18,000-dalton class contained two protein components, and the 11,000-dalton class contained one major component. The N-terminal residues for the 43,000- and the 11,000-dalton classes were alanine, and the N-terminal residues for the 18,000-dalton class were methionine and alanine. Of the three classes of proteins, the 18,000-dalton proteins were the most acidic, whereas the 11,000-dalton proteins were the most basic. The amino acid composition of the 11,000-dalton class revealed that methionine and cysteine were absent and lysine, histidine, and tryptophan content was higher in the 11,000-dalton class than in the other two classes of proteins. Estimates of the relative number of the three classes of structural proteins were made and indicated that there were between 1,600 and 2,000 subunits of the 43,000-dalton proteins, 100 to 200 of the 18,000-dalton proteins, and 1,000 to 1,500 of the 11,000-dalton proteins. Evidence was presented that the 43,000-dalton proteins and the 11,000-dalton proteins readily formed aggregates with themselves but not with each other. The significance of these interactions to the structure of the T-even phage head was discussed.
Preliminary Physiological Characterization of Temperature-Sensitive Mutants of Vesicular Stomatitis Virus
Authors: Pringle C. R. , Duncan I. B.
Published: January 2020

Different temperature-sensitive mutants of vesicular stomatitis virus have been characterized in terms of their ability to induce synthesis of viral ribonucleic acid (RNA) in BHK-21 cells at 39 C (the restrictive temperature for these mutants). Mutants belonging to complementation groups I and IV (and probably II) did not induce actinomycin-resistant RNA synthesis in infected cells incubated at 39 C. All three mutants comprising complementation group III induced viral RNA synthesis at 39 C. The temperature sensitivity of the defective viral functions has also been studied by temperature-shift experiments. The functions associated with the mutants of groups I, II, and IV were required early, whereas the function associated with the group III mutants was not required until a late stage of the viral cycle. The heat sensitivity of extracellular virion was not correlated with complementation group.
Initial Stage of Transformation of Permissive Cells by Simian Virus 40: Development of Resistance to Productive Infection
Authors: Hahn E. C. , Sauer G.
Published: January 2020

A quantitative assay has been used to determine the conditions leading to acquisition of resistance of permissive cells to lytic infection. The number of cell colonies surviving infection depends on the occurrence of several cell divisions after infection. High yields of resistant colonies were obtained when infected, confluent cultures were released from contact inhibition 10 to 14 hr after infection. Infection of actively growing cells produced similar results, but halting further division by seeding these growing cells on confluent monolayers prevented the development of colonies. Colony formation was a direct function of multiplicities lower than 5. An inverse killing response was observed with higher multiplicities, yet colonies were produced at a multiplicity of infection as high as 50. Brief exposure of input simian virus 40 to ultraviolet light stimulated colony formation. Irradiation of the virus for longer periods of time led to reduction of colony formation at a rate slower than the rate of inactivation of viral infectivity. It was concluded that resistance is induced by simian virus 40 and that this alteration represents one of the earliest detectable characteristics of the transformation of permissive cells.
Acid Phosphatase Activity in Mouse Brain Infected with Venezuelan Equine Encephalomyelitis Virus
Authors: Garcia-Tamayo Jorge
Published: January 2020

The mode of development of Venezuelan equine encephalomyelitis virus and the activity of acid phosphatase in the central nervous system of newborn mice were investigated. Precursor particles appeared to be formed in masses of viroplasm, migrating to the membrane of the Golgi cisterns and vacuoles or to the plasma membrane and being transformed into mature viral particles by budding. Mature viral particles were also found in the lumen of the blood vessels and around the myelin sheath of axons. Increased number of Golgi complexes and depletion of polysomes were the main ultrastructural alterations of the nerve cells. Acid phosphatase activity was found to be increased in the Golgi cisterns, vacuoles, and lysosomes of nerve cells. The presence of acid phosphatase activity in the rough endoplasmic reticulum and perinuclear cisterns suggests increased production of the enzyme in the nerve cells infected with Venezuelan equine encephalomyelitis virus.
Ribonucleic Acid Bacteriophage Release: Requirement for Host-Controlled Protein Synthesis
Authors: Engelberg Hanna , Soudry Esther
Published: January 2020

The release of the ribonucleic acid (RNA)-containing phage MS2 from
Escherichia coli
is accompanied by cellular lysis at 37 C, whereas at 30 C phage are released from intact cells. Chloramphenicol or rifampin prevents the release of progeny phage particles at both temperatures. Neither drug causes an immediate cessation of phage release and after inhibition of protein synthesis by chloramphenicol phage release proceeds for about 17 min at 37 C and about 35 min at 30 C. Rifampin does not inhibit phage release from mutant cells possessing a rifampin-resistant deoxyribonucleic acid-dependent RNA polymerase. The results indicate that a short-lived host-controlled protein(s) is essential for the release of RNA phage particles at both temperatures.
Escherichia coli
Capsule Bacteriophages II. Morphology
Authors: Stirm Stephan , Freund-Mölbert Elisabeth
Published: January 2020

The
Escherichia coli
capsule bacteriophages (K phages) described herein are specific for certain capsular strains of
E. coli
, all of them test strains for different
E. coli
K antigens. The phages are not adsorbed to the acapsular mutants of their host organisms nor to similar strains with serologically and chemically different capsular polysaccharides. Thirteen
E. coli
(and one
Klebsiella
) K phages were visualized in the electron microscope. Most viruses are similar to P22 and thus belong to Bradley group C; however, one each of group A (long, contractile tail) and group B (long, noncontractile tail) was also found. All K phages were seen to carry spikes but no tail fibers were detected. These results suggest that the structures responsible for the recognition of the thick (about 400 nm or more) capsular polysaccharide gels are located in these spikes.
Homologous Interference by Incomplete Sendai Virus Particles: Changes in Virus-Specific Ribonucleic Acid Synthesis
Authors: Portner A. , Kingsbury D. W.
Published: January 2020

Incomplete Sendai virus particles (I particles) interfered with the replication of several strains of infectious Sendai virions (standard virus) but not with the replication of Newcastle disease virus, mumps virus, or Sindbis virus. I particles did not induce interferon, and ultraviolet irradiation of I particles abolished their ability to interfere. Protein synthesis was not necessary to establish interference. The degree of interference depended on the interval between exposure of cells to the I particles and challenge by standard virus, and this was reflected in the degree of inhibition of virus-specific ribonucleic acid (RNA) synthesis in infected cells. The most dramatic change was decreased accumulation of 50
S
virus-specific RNA in infected cells. RNA species sedimenting slower than 50
S
were not as markedly reduced in total amount, but hybridization experiments showed that a substantial portion of these slowly sedimenting RNA species were plus strands, presumably representing replicas of the RNA species in I particles. When I particles in insufficient numbers to interfere were added to cells as late as 8 hr after standard virus, there were no obvious changes in virus-specific RNA species in the cells; however, significant amounts of 19 and 25
S
RNA species, representing progeny of the I particles, appeared in the culture medium. It was concluded that interference was an intracellular event affecting an early step in virus replication. Competition by I particles for cell sites or substrates needed by standard virus seemed a less likely mechanism of interference than competition for enzymes specified by standard virus.
Channel Catfish Virus: a New Herpesvirus of Ictalurid Fish
Authors: Wolf Ken , Darlington Robert W.
Published: January 2020

Channel catfish virus was studied in ictalurid fish cell culture, the only system of fish, amphibian, avian, and mammalian cells found to be susceptible. Channel catfish virus infection resulted in intranuclear inclusions and extensive syncytium formation. Replication occurred from 10 to 33 C, but not higher. Best growth was from 25 to 33 C, and the amount of virus released nearly equalled the amount which remained cell-associated. The virus was labile to lipid solvents, and indirect determinations with labeled precursors and a metabolic inhibitor showed evidence of deoxyribonucleic acid. Electron microscopy showed progeny virus, about 100 nm in diameter, in various stages of development in cell nuclei by 4 hr. Present also were nuclear masses of exceptionally electron-dense lamellar material, with a unit dimension of 10 to 15 nm. Virus was enveloped at the nuclear membrane and in cytoplasmic vacuoles, resulting in virions having a diameter of 175 to 200 nm. Negative staining demonstrated icosehedral symmetry and 162 capsomeres. Our data indicate that channel catfish virus is a herpesvirus.
Ribonuclease-Sensitive Deoxyribonucleic Acid Polymerase Activity in Uninfected Rat Cells and Rat Cells Infected with Rous Sarcoma Virus
Authors: Coffin John M. , Temin Howard M.
Published: January 2020

Rat cells infected with the B77 strain of avian sarcoma virus [R(B77) cells] produced no virus-like particles but contained information for the production of infectious B77 virus.
3
H-labeled deoxyribonucleic acid (DNA) product of the B77 virus endogenous DNA polymerase system was used to determine the relative amounts of B77 virus-specific ribonucleic acid (RNA) in B77 virus-infected chicken and R(B77) cells. R(B77) cells were found to contain much less B77 virus RNA than did B77 virus-infected chicken cells. Ribonuclease-sensitive DNA polymerase activity was present in high-speed pellet fractions from Nonidet extracts of B77 virus-infected rat cells. Similar preparations from some uninfected rat cells contained lesser amounts of a similar ribonuclease-sensitive DNA polymerase activity. The endogenous template for the DNA polymerase activity in high-speed pellet fractions from R(B77) cells was not related to B77 virus RNA or to RNA of a rat C-type virus. The DNA product of the endogenous DNA polymerase in high-speed pellet fractions of R(B77) cells hybridized to a small extent with RNA from the same fraction and to a similar extent with RNA from uninfected rat cells.
Nature of Transient Inhibition of Deoxyribonucleic Acid Synthesis in HeLa Cells by Parainfluenza Virus 1 (Sendai)
Authors: Fuchs Pinhas , Kohn Alexander
Published: January 2020

Adsorption of ultraviolet-inactivated Sendai virus, at high or low multiplicity, to HeLa cells caused a transient increased incorporation of
3
H-thymidine into the cellular deoxyribonucleic acid (DNA). In HeLa cells synchronized by a double-thymidine block, this increased incorporation of thymidine during the S phase lasted from about 30 to 90 min after virus adsorption. The observations that the kinetics of accumulation of radioactive thymidine in the nucleotide pool did not differ in control and in the virus-treated cells and that the
32
P incorporation into the DNA of the virus-treated cells was inhibited at the same time indicate that the augmented incorporation of
3
H-thymidine into DNA results from a transient block in the endogenous pathway of thymidine synthesis. Chromatographic analysis of the nucleotide pool of the virus-treated cells labeled with
14
C-formate indicates that methylation of deoxyuridine monophosphate to thymidine monophosphate is inhibited. It is suggested that the inhibition is caused by a block of either the thymidilate synthetase or some step in the tetrahydrofolate cycle.
Chromatographic Separation and Antigenic Analysis of Proteins of the Oncornaviruses
Authors: Fleissner Erwin
Published: January 2020

Gel filtration of avian tumor virus proteins in 6
m
guanidine hydrochloride clearly resolved seven major protein species. The antigenic activity of these proteins was recovered in good yield after removal of the denaturing solvent, permitting a correlation of specific polypeptides with the principal antigens of the virion. Two of the proteins, of molecular weights 70,000 and 32,000, contain carbohydrate and are situated on the viral membrane, as shown by their being accessible in the intact virus to specific antibodies. Four proteins, with molecular weights (in guanidine) of 27,000, 19,000, 15,000, and 12,000, have different group-specific (gs) antigens and are enclosed within the viral membrane. The smallest protein, with a molecular weight of 10,000, has not previously been described; it is not detectable with antisera and possesses a mobility identical to that of one gs protein when subjected to electrophoresis in polyacrylamide gels in the presence of sodium dodecyl sulfate. Of the proteins lacking carbohydrate, three are present in the virion in a molecular ratio of 2:2:1, and the two others, present in almost equal amount, are rich in lysine and arginine.
Inactivation of Polykaryocytogenic and Hemolytic Activities of Sendai Virus by Phospholipase B (Lysolecithinase)
Authors: Barbanti-Brodano G. , Possati L. , La Placa M.
Published: January 2020

Evidence is presented that lysolecithin is involved in the fusing and hemolytic activities of Sendai virus. Treatment of the virus with phospholipase B (lysolecithinase) specifically inactivates the hemolytic and fusing abilities, without affecting the infectivity and the capability of the virus to hemagglutinate and adsorb to cells. The possible identity of lysolecithin with the “cell fusion factor” of paramyxoviruses and the mechanism of cell fusion are discussed.
Component of Strain MC29 Avian Leukosis Virus with the Property of Defectiveness
Authors: Ishizaki R. , Langlois A. J. , Chabot J. , Beard J. W.
Published: January 2020

Three clones of morphologically altered cells (L
−
MC29) of singular properties were isolated from MC29 (subgroup A) leukosis virus-infected chick embryo cells. Supernatant fluids from cultures of the cloned cells produced no transforming or interfering activity on chick embryo cells susceptible to known avian leukosis-sarcoma viruses. No virus associated with the cells was demonstrable by fluorescent-antibody staining or by electron microscopy. All L
−
MC29 clone cells were activated, however, by four strains of Rous-associated viruses (RAV) representative of A, B, C, and D subgroup avian leukosis viruses and by two strains of MC29 virus. Virus L
−
MC29 cells activated by superinfection with RAV-1 and RAV-2 was characterized by helper-dependent and helper-independent properties. These findings suggest that the strain MC29 leukosis virus, or a component thereof, possesses properties of defectiveness similar to those of the Bryan high-titer Rous sarcoma virus.
Immunological Relationships of Reverse Transcriptases from Ribonucleic Acid Tumor Viruses
Authors: Parks Wade P. , Scolnick Edward M. , Ross Jeffrey , Todaro George J. , Aaronson Stuart A.
Published: January 2020

Antiserum to partially purified reverse transcriptase from the Schmidt-Ruppin strain of Rous sarcoma virus has been prepared and characterized. Antibody to the avian polymerase inhibited the reverse transcriptase activity of avian C-type viruses but had no effect on the polymerase activity from C-type viruses of other classes. The known mammalian C-type viral polymerases were significantly inhibited only by the antiserum to murine C-type viral polymerases; reverse transcriptases from four other mammalian viruses were immunologically distinct from both avian and mammalian C-type viral polymerases. Partially purified murine leukemia viral DNA polymerase activity was comparably reduced by specific antibody regardless of the template used for enzyme detection.
RNA-Dependent DNA Polymerase Activity of RNA Tumor Viruses I. Directing Influence of DNA in the Reaction
Authors: Hurwitz Jerard , Leis Jonathan P.
Published: January 2020

The template requirements and deoxyribonucleic acid (DNA) products of the DNA polymerases isolated from Rauscher leukemia and avian myeloblastosis viruses have been examined. All DNA preparations or synthetic polydeoxynucleotides which are active as primers possess a duplex structure containing single-stranded regions with a 3′-hydroxyl terminus. Native DNA and fully single-stranded DNA are inactive; moreover, their activity is not enhanced by sonic oscillation or treatment with micrococcal nuclease,
Neurospora
nuclease, or low levels of deoxyribonuclease I. Poor DNA templates are activated by treatment with exonuclease III, large amounts of deoxyribonuclease I, or an endonuclease isolated from Rauscher viral preparations. In reactions primed with deoxyadenylate-deoxythymidylate copolymer, the product formed is covalently attached to primer strands, indicating that no new strands are initiated. DNA polymerase products formed with exonuclease III- or deoxyribonuclase I-treated DNA are duplex structures. Short single-stranded regions are completely filled in, whereas long single-stranded regions are only partly repaired. DNA preparations containing extensive single-stranded regions are poorly utilized as templates.
RNA-Dependent DNA Polymerase Activity of RNA Tumor Viruses II. Directing Influence of RNA in the Reaction
Authors: Leis Jonathan P. , Hurwitz Jerard
Published: January 2020

The role of ribonucleic acid (RNA) in deoxyribonucleic acid (DNA) synthesis with the purified DNA polymerase from the avian myeloblastosis virus has been studied. The polymerase catalyzes the synthesis of DNA in the presence of four deoxynucleoside triphosphates, Mg
2+
, and a variety of RNA templates including those isolated from avian myeloblastosis, Rous sarcoma, and Rauscher leukemia viruses; phages f2, MS2, and Qβ; and synthetic homopolymers such as polyadenylate·polyuridylic acid. The enzyme does not initiate the synthesis of new chains but incorporates deoxynucleotides at 3′ hydroxyl ends of primer strands. The product is an RNA·DNA hybrid in which the two polynucleotide components are covalently linked. Free DNA has not been detected among the products formed with the purified enzyme in vitro. The DNA synthesized with avian myeloblastosis virus RNA after alkaline hydrolysis has a sedimentation coefficient of 6 to 7
S
.
Reduction and Reoxidation of Australia Antigen: Loss and Reconstitution of Particle Structure and Antigenicity
Authors: Sukeno Noriyoshi , Shirachi Ryoichi , Yamaguchi Junji , Ishida Nakao
Published: January 2020

Reduction of Australia antigen with dithiothreitol resulted in the loss of antigenicity and morphological integrity. Oxidation of the reduced Australia antigen reconstituted both of these characters.
Selective Inhibition of the Synthesis of Sindbis Virion Proteins by an Inhibitor of Chymotrypsin
Authors: Pfefferkorn E. R. , Boyle Mary K.
Published: January 2020

Treatment of chick embryo fibroblasts infected with Sindbis virus with TPCK, the choloromethyl ketone derivative of tosyl-phenylalanine and an inhibitor of chymotrypsin, resulted in reduced synthesis of viral structural proteins and the accumulation of a high-molecular-weight polypeptide, thought to be a precursor. The analogous inhibitor of trypsin, TLCK, the chloromethyl ketone derivative of tosyllysine, had no such effect.
Synthesis and Assembly of Simian Virus 40 II. Synthesis of the Major Capsid Protein and Its Incorporation into Viral Particles
Authors: Ozer Harvey L. , Tegtmeyer Peter
Published: January 2020

African green monkey kidney cells infected by simian virus 40 were analyzed for the presence of the major capsid protein (capsid protein I) by immunological and radiolabeling techniques. Antisera with different specificities were prepared by immunization with intact or denatured viral particles. Antisera prepared against intact virus reacted by complement fixation with viral particles and with an 8
S
subunit containing the capsid protein I. Antisera prepared against denatured viral particles reacted with unassembled capsid protein(s) as well as with viral particles. These antisera were used to detect 8
S
viral subunits or unassembled viral capsid protein in soluble extracts of infected cells after centrifugation at 100,000 ×
g
to remove viral particles. The soluble antigen pool was found to be small during infection with wild-type virus or a temperature-sensitive mutant deficient in the synthesis of viral particles. Pulse-chase experiments, performed at a high multiplicity of infection, also indicated a small pool of nonparticle capsid protein I. Radioactive lysine was incorporated into capsid protein I of virus particles during a 2-hr pulse. A subsequent chase with excess unlabeled lysine resulted in only a slight increase in the radio-activity found in capsid protein I of viral particles. Furthermore, in the same experiments, capsid protein I was incorporated preferentially into empty shells during the pulse with a shift in radioactivity to intact virions during the chase period, indicating a possible precursor relationship between the two types of virus particles.
Temperature-Sensitive Mutants Isolated from L Cells Persistently Infected with Newcastle Disease Virus
Authors: Preble Olivia T. , Youngner Julius S.
Published: January 2020

Virus mutants (NDV
pi
) isolated from L cells persistently infected with the Herts strain of Newcastle disease virus have been previously reported by this laboratory to differ from the wild-type virus (NDV
o
) in several physical and biological properties. It has now been determined that, in addition to these differences, the NDV
pi
mutants are also spontaneously selected temperature-sensitive mutants. The temperature sensitivity of 10 NDV
pi
clones was confirmed by temperature inhibition, plaquing efficiency, and single-cycle yield experiments. The cut-off temperature, at which more than 90% of virus replication is inhibited was between 41 and 42 C. All 10 NDV
pi
clones were also found to be defective in virus-specific ribonucleic acid (RNA) synthesis in infected chick embryo cells at 42 C and are tentatively classified as RNA
−
. The possible relationships of the temperature sensitivity, the other NDV
pi
properties, and the maintenance of the persistently infected state are discussed.
Protein Kinase Activity in Equine Herpesvirus
Authors: Randall Charles C. , Rogers Howell W. , Downer Donald N. , Gentry Glenn A.
Published: January 2020

A protein kinase which is intimately associated with equine herpesvirus (equine abortion virus) was found by using adenosine triphosphate-γ-
32
P as a phosphate donor and virus protein as an acceptor. Consistent demonstration of the activity requires prior removal of phosphohydrolase. The kinase activity requires Mg
2+
, is not stimulated by cyclic adenosine monophosphate, but is enhanced by added protamine or arginine-rich histone. The labeled product is resistant to ribonuclease, deoxyribonuclease, and chloroform-methanol but is sensitive to Pronase. Other tests suggest that serine and threonine residues are the acceptor sites. In the in vitro reaction, the incorporation represents an average of approximately 4,500 phosphate residues per virion, and all 17 virus protein bands resolved by polyacrylamide gel electrophoresis appear to be labeled.
Cell-Dependent Differences in the Production of Infectious Herpes Simplex Virus at a Supraoptimal Temperature
Authors: Crouch Norman A. , Rapp Fred
Published: January 2020

The replication of herpes simplex virus (HSV) was compared in rabbit and hamster cells at optimal and supraoptimal temperatures. Replication occurred in cells of either species at 33 C, but the total infectious virus yield was routinely about 10-fold greater in rabbit cells than in hamster cells. At 39 C, this difference was exaggerated to greater than 100,000-fold. Whereas infectious virus was produced and plaques formed in rabbit kidney cell monolayers at the higher temperature, neither developed in those derived from hamster embryos. Elevating the temperature from 33 C to 39 C at various time intervals after exposure of the cultures to virus revealed that production of infectious virus in hamster cells was completely heat-sensitive up to 6 hr after infection. Specific viral antigens and viral deoxyribonucleic acid (DNA) were synthesized in both rabbit and hamster cell cultures. In addition, cellular DNA synthesis was depressed and cytopathic effects occurred in both cell systems. These cytopathic effects were not observed in cell cultures treated with HSV previously inactivated with ultraviolet light. Compared with parallel cultures at 33 C, the amount of viral DNA synthesized at 39 C was greatly reduced in both systems. In hamster cells, the reduction was twofold greater than in rabbit cells. This cell-dependent thermal inhibition of HSV replication in hamster cells did not occur with vaccinia virus.
Transfer Ribonucleic Acid Synthetase Activity Associated with Avian Myeloblastosis Virus
Authors: Erikson Eleanor , Erikson R. L.
Published: January 2020

Avian myeloblastosis virions purified by conventional techniques were shown to be associated with or to contain transfer ribonucleic acid synthetase activity. Arginine, tryptophan, cystine, and lysine synthetase activities were observed.
Characterization of Temperate Actinophage φC31 Isolated from
Streptomyces coelicolor
A3(2)
Authors: Lomovskaya N. D. , Mkrtumian N. M. , Gostimskaya N. L. , Danilenko V. N.
Published: January 2020

Actinophage φC31 isolated from
Streptomyces coelicolor
A3(2), the only strain among actinomycetes for which a genetic map had been constructed, appears to be a typical temperate phage. After φC31 infection, true lysogenic cultures arose which liberated phage and were immune to infection with homologous phage after repeated single-colony isolations and treatment with phage-specific antiserum. Clear-plaque (c) mutants were derived from φC31 phage which failed to lysogenize sensitive cultures. Actinophage φC31 has a temperature-sensitive stage of reproduction. A phage which reproduces with the same effectiveness at high (37 C) and low (28 C) temperatures has also been obtained. Heat-inducible (ct) mutants were isolated from this phage which were able to lysogenize sensitive cultures at 28 C but failed to do so at 37 C. Properties of ct mutants suggest that ct mutations involve a gene controlling maintenance of the lysogenic state in actinomycetes and synthesizing repressor, which may become heat-sensitive as a result of mutation.
Transduction of Gal
+
by Coliphage T1 II. Role of λ Transcription Control in the Efficiency of Transduction
Authors: Drexler Henry
Published: January 2020

One of the crossovers leading to the transduction of
Escherichia coli
W3350 or one of its derivatives for the Gal
+
marker by T1 grown on donors lysogenic for λ must occur to the right of the galactose operon. The location of this crossover determined both the rate of transduction and the λ genes which control the transduction by (λ-
gal
)T1. When the crossover occurred either to the left of gene N or the right of the cI gene, it was affected in a positive fashion by the gene product of the N
+
gene. When the crossover occurred either to the left of gene N or between N and gene Q, its efficiency was not significantly affected by the expression of Q
+
. However, crossovers to the right of gene Q were greatly stimulated by the presence of a functioning Q gene on the chromosome of (λ-
gal
)T1 hybrid. The repressor made by the cI
+
gene of λ blocked efficient transduction. Therefore, the control of efficient transduction by (λ-
gal
)T1 is the same as the control of transcription of λ. It is concluded that the increased efficiency of transduction by (λ-
gal
)T1 in nonimmune recipients is not caused by any particular product of a gene but rather by the process of transcription itself.
Photoreactivation of a Cytoplasmic Virus
Authors: Pfefferkorn E. R. , Boyle Mary K.
Published: January 2020

Ultraviolet light-inactivated frog virus 3 is efficiently photoreactivated by chick embryo cells. A cellular enzyme is presumably responsible for this repair of viral deoxyribonucleic acid, for the phenomenon is insensitive to an inhibitor of protein synthesis and is not seen in mammalian cells that are known to lack photoreactivating enzyme. Since frog virus 3 is a cytoplasmic virus, functionally significant amounts of photoreactivating enzyme are probably present in the cytoplasm of chick embryo cells.
Deficiency of Viral Ribonucleic Acid-Dependent Deoxyribonucleic Acid Polymerase in Noninfectious Virus-Like Particles Released from Murine Sarcoma Virus-Transformed Hamster Cells
Authors: Peebles P. T. , Haapala D. K. , Gazdar A. F.
Published: January 2020

Virions from hamster cells transformed by a new strain of murine sarcoma virus (MSV) appear to represent a form of MSV deficient in one or more of the viral components necessary for infectivity. Both the noninfectious virions and the sarcoma virus-transformed cells, which have no detectable replicating leukemia helper virus of either murine or hamster origin, are deficient in viral-type ribonucleic acid (RNA)-dependent deoxyribonucleic acid (DNA) polymerase activity (i.e., reverse transcriptase activity stimulated by the synthetic RNA-DNA template polyribo-adenylic-oligodeoxythymidylic acid). In comparison, both murine leukemia virus (MuLV) and MuLV-infected cells have abundant viral-type reverse transcriptase activity. It appears, therefore, that the leukemia virus genome may be required for the production of infectious sarcoma virus by contributing information needed for the full expression of functional viral-type reverse transcriptase.
Dominance Relationships in Mixedly Infected
Bacillus subtilis
Authors: Palefski Sandra , Hemphill H. Ernest , Kolenbrander P. E. , Whiteley H. R.
Published: January 2020

The progeny released from
Bacillus subtilis
cells mixedly infected with bacteriophages β22, SP82, and SP02
c1
have been studied at varying multiplicities of infection and orders of addition and with different host strains of the bacterium. In
B. subtilis
168, SP02
c1
was subordinate to both SP82 and β22 and did not yield significant numbers of progeny even when added 5 min before the superior phage. Dominance in mixed infections of β22 and SP82 was host-dependent. In
B. subtilis
168, SP82 was dominant and greatly reduced the yield of β22 if added simultaneously or before the subordinate partner. However, in the same mixed infection in
B. subtilis
SB11, β22 was the dominant phage and totally suppressed the production of SP82 even when added 5 min after the latter.
A Bacteriophage of
Bacillus subtilis
Which Forms Plaques Only at Temperatures Above 50 C III. Inhibition of TSP-1-Specific Deoxyribonucleic Acid Synthesis at 37 C and 45 C
Authors: LaMontagne J. R. , McDonald W. C.
Published: January 2020

The effect of temperature on phage-specific deoxyribonucleic acid (DNA) synthesis was studied in TSP-1-infected
Bacillus subtilis.
This was facilitated by selectively inhibiting host DNA synthesis with 6-(
p
-hydroxyphenylazo)-uracil. The results indicated that TSP-1 DNA synthesis did not continue at 37 C and was immediately shut down after transfer to this temperature. Incubation at 45 C greatly reduced TSP-1 DNA synthesis. Phage-specific DNA synthesis could resume at 53 C, however, when the infected culture was returned to 53 C after a 2-min incubation period at 37 C. The results suggest that the inhibition of phage DNA synthesis at 37 C is reversible. Since infected cultures returned to 53 C after 2 min at 37 C could not complete the replicative cycle, the irreversible inhibition of yet another intermediate step was suggested.
Unrelatedness of Temperate
Bacillus subtilis
Bacteriophages SPO2 and φ105
Authors: Rutberg Lars , Armentrout Richard W. , Jonasson Jon
Published: January 2020

SPO2 and φ105 are temperate
Bacillus subtilis
bacteriophages which have been suggested to belong to a cluster of related bacteriophages. In the present work, we show that SPO2 does not complement any of the 11 essential genes known in φ105 and that the phages do not recombine. Deoxyribonucleic acid (DNA)-DNA hybridization shows less than 10% homology between SPO2 and φ105 DNA. DNA synthesis in φ105 shows a greater dependence on host functions than does SPO2 DNA synthesis. Growth of φ105 but not of SPO2 is inhibited by the uracil analogue 6-(
p
-hydroxyphenylazo)-uracil. Infection of a DNA polymerase-deficient strain of
B. subtilis
with SPO2 leads to an increase in DNA polymerase activity in crude extracts, whereas no such increase is found after infection of this strain with φ105. It is concluded that SPO2 and φ105 are unrelated bacteriophages.
Effect of R17 Bacteriophage-Specific Proteins on Ribosomal Ribonucleic Acid Synthesis of
Escherichia coli
Authors: Spangler Virginia L. , Iglewski Wallace J.
Published: January 2020

Bacteriophage R17 and a series of amber mutants of R17 were used to infect cultures of
Escherichia coli.
The ribonucleic acid (RNA) of these cultures was radio-actively labeled, extracted, and subjected to polyacrylamide gel electrophoresis. Synthesis of ribosomal RNA was inhibited in cultures infected with the wild-type R17 and in cultures infected with phage mutants retaining the ability to produce viral polymerase. With the exception of one mutant tested, the degree of inhibition of ribosomal RNA synthesis in infected cells was correlated with the amount of viral polymerase synthesized. Maturation of 16
S
ribosomal RNA from its 17
S
RNA precursor appeared normal in infected cells, indicating that the inhibition of 16
S
ribosomal RNA synthesis occurred solely at the transcriptional level.
Regulation of Bacteriophage T5 Development by ColI Factors
Authors: Moyer R. W. , Fu A. S. , Szabo C.
Published: January 2020

The I-type colicinogenic factor ColIb transforms
Escherichia coli
from a permissive to a nonpermissive host for bacteriophage T5 reproduction by preventing complete expression of the phage genome. T5-infected ColIb
+
cells synthesize only class I (early) phage protein and ribonucleic acid (RNA). Neither phage-specific class II proteins [associated with viral deoxyribonucleic acid (DNA) replication] nor class III proteins (phage structural components) are formed due to the failure of the infected ColIb
+
cells to synthesize class II or class III phage-specific messenger RNA. Comparable studies with T5-infected cells colicinogenic for the related ColIa factor revealed no decrease in the yield of progeny phage although the presence of the ColIa factor leads to a significant reduction in the amount of phage-directed class III protein synthesis.
Gene Order of Encephalomyocarditis Virus as Determined by Studies with Pactamycin
Authors: Butterworth Byron E. , Rueckert Roland R.
Published: January 2020

Previous work has shown that translation of the encephalomyocarditis (EMC) viral ribonucleic acid (RNA) generates at least three primary products, polypeptides A, F, and C. The A and C polypeptides then undergo post-translational cleavages to complete the production of the stable viral polypeptides (δ, β, γ, α, G, I, F, H, and E). In this communication we show that A, F, and C are produced in equimolar amounts giving further support to the theory that the RNA of picornaviruses has only a single site for the initiation of protein synthesis. The biosynthesis of viral proteins in EMC virus-infected HeLa cells was studied in the presence of pactamycin at concentrations which preferentially inhibit the initiation of protein synthesis. The amount of each polypeptide formed during the residual period of protein synthesis observed after the addition of pactamycin was used as a criterion for ordering the genes on the viral RNA. The results obtained indicate that the primary gene products are ordered on the EMC viral RNA 5′ → 3′ A-F-C and that the stable products are ordered δ-β-γ-α-G-I-F-H-E. Moreover, the intermediate chains B and ε map in the capsid region, whereas the intermediate chain D maps in the E region. This order is largely consistent with previously established relationships of the viral polypeptides and thus indicates that pactamycin is a valid tool for “genetic” mapping of polycistronic RNA molecules with single initiation sites.
Bacteriophage T4 Head Models Based on Icosahedral Symmetry
Authors: Walker D. H. , Mosig G. , Bayer M. E.
Published: January 2020

In an accompanying paper, the coordinate variation in lengths of deoxyribonucleic acid molecules and head lengths in morphological variants of bacteriophage T4 is discussed. As an appendix to that report, models for the T4 phage heads, based on previously developed architectural principles for assembly of icosahedral virus, are compared with the data for the best fit.
Release of Rubella Virus Ribonucleic Acid from Ribonucleoprotein by Polyanions
Authors: Hovi Tapani
Published: January 2020

Rubella virus ribonucleoprotein was accessible to pancreatic ribonuclease, Pronase, and certain polyanions. Most of the ribonucleic acid (RNA) label was made acid-soluble by ribonuclease, whereas Pronase and the polyanions liberated 40
S
RNA from the ribonucleoprotein.
Ultraviolet-Induced Cross-Links in the Deoxyribonucleic Acid of Single-Stranded Deoxyribonucleic Acid Viruses as a Probe of Deoxyribonucleic Acid Packaging
Authors: Francke Bertold , Ray Dan S.
Published: January 2020

Deoxyribonucleic acid (DNA) from ultraviolet (UV)-irradiated φX174 sediments in alkali at rates up to 1.7 times that of unirradiated φX174 DNA and is observed as a condensed, cross-linked structure when examined in the electron microscope by the formamide spreading technique. This structure appears to result from multiple cross-links induced in the tightly coiled DNA contained within the spherical φX174 capsid. In contrast, the DNA extracted after UV irradiation of the filamentous bacteriophage M13 is not strikingly altered in its sedimentation properties and appears by electron microscopy to be rod-shaped as a result of side-to-side association of the circular DNA. The differences in these UV-induced structures reflect the differences in the packaging of the single-stranded DNA in the two virions.
Ribonucleic Acid Synthesis of Vesicular Stomatitis Virus IV. Transcription by Standard Virus in the Presence of Defective Interfering Particles
Authors: Huang Alice S. , Manders Ernest K.
Published: January 2020

Exposure of vesicular stomatitis virus-infected Chinese hamster ovary cells to cycloheximide results in the complete transcription of virion ribonucleic acid (RNA) into only 28
S
and 13 to 15
S
viral-specific RNA species. These RNA are identical to viral messenger RNA by the following criteria: size, single-strandedness, complementarity to virion RNA, and formation of messenger ribonucleoproteins. This transcription represents the intracellular enzymatic activity of the virion-associated polymerase and is shown to be dependent on input multiplicity. Intracellular transcription differs from in vitro polymerase activity in having a temperature optimum of 34 to 37 C and in synthesizing 28
S
as well as 13 to 15
S
messenger RNA species. Addition of interfering quantities of defective T particles to these cycloheximide-treated cells, either an hour before or at the same time as standard B particles of vesicular stomatitis virus, does not alter the rate of transcription nor does it change the sucrose gradient pattern of the viral RNA species. From these results it is concluded that the RNA of defective T particles does not serve a transcriptive function and probably interferes through the replicative mechanism for virion RNA synthesis.
Synthesis In Vitro of Type 5 Adenovirus Capsid Proteins
Authors: Wilhelm James M. , Ginsberg Harold S.
Published: January 2020

Reaction mixtures containing cytoplasmic extracts and ribosomal fractions prepared from KB cells infected with type 5 adenovirus were able to carry out incorporation of amino acids into protein. The in vitro product included proteins which reacted specifically with antisera to adenovirus capsid proteins; in control experiments with extracts from uninfected cells, no reactions with the antisera were found. The viral proteins were synthesized in vitro on small polyribosomes, were released from them, and significant numbers of the free polypeptides were assembled in vitro into multimeric adenovirus capsid structures.
Comparative Transcriptomic and Functional Assessments of Linezolid-Responsive Small RNA Genes in Staphylococcus aureus
Authors: Gao Wei , Guérillot Romain , Lin Ya Hsun , Tree Jai , Beaume Marie , François Patrice , Monk Ian R. , Seemann Torsten , Schrenzel Jacques , Howden Benjamin P. , Stinear Timothy P.
Published: January 2020

Bacterial small RNAs (sRNAs) are RNA molecules that can have important regulatory roles across gene expression networks. There is a growing understanding of the scope and potential breadth of impact of sRNAs on global gene expression patterns in
Staphylococcus aureus
, a major human pathogen. Here, transcriptome comparisons were used to examine the roles of sRNA genes with a potential role in the response of
S. aureus
to antibiotic exposure. Although no measurable impact on key bacterial phenotypes was observed after deleting each of 18 sRNAs identified by these comparisons, this research is significant because it underscores the subtle modes of action of these sometimes abundant molecules within the bacterium.
Management of afferent loop syndrome after Roux-en-Y subtotal gastrectomy and choledocolithiasis with recurrent cholangitis
Authors: Azevedo Fernando , Canhoto Carolina , Tralhão José Guilherme , Carvalho Hélder
Published: January 2020

Afferent loop syndrome is a rare complication after gastrectomy with Billroth II or Roux-en-Y reconstruction, caused by an obstruction in the proximal loop. The biliary stasis and bacterial overgrowth secondary to this obstruction can lead to repeated episodes of acute cholangitis. We present the case of a male patient who had previously undergone gastrectomy with Roux-en-Y reconstruction and later experienced multiple episodes of acute cholangitis secondary to choledocolithiasis. He underwent an open exploration of the bile ducts with choledocolitotomy, but the events of cholangitis persisted. Further investigation permitted to identify a dilation of the biliary loop of the Roux-en-Y anastomosis, suggesting enterobiliary reflux as the cause of recurrent acute cholangitis. Therefore, a bowel enterectomy and new jejunojejunostomy were undertaken, and normal biliary flow was re-established. The surgical treatment is mandatory in benign causes, leading to the resolution of the obstruction and subsequent normalisation of bile flow.
Patient and caregiver priorities in the transition from hospital to home: results from province-wide group concept mapping
Authors: Kiran Tara , Wells David , Okrainec Karen , Kennedy Carol , Devotta Kimberly , Mabaya Gracia , Phillips Lacey , Lang Amy , O'Campo Patricia
Published: January 2020

Background

Patients and caregivers often face significant challenges when they are discharged home from hospital. We sought to understand what influenced patient and caregiver experience in the transition from hospital to home and which of these aspects they prioritised for health system improvement.

Methods

We conducted group concept mapping over 11 months with patients—and their caregivers—who were admitted to a hospital overnight in the last 3 years in Ontario, Canada and discharged home. Home included supportive housing, shelters and long-term care. Participants responded to a single focal prompt about what affected their experience during the transition. We summarised responses in unique statements. We then recruited participants to rate each statement on a five-point scale on whether addressing this gap should be a priority for the health system. The provincial quality agency recruited participants in partnership with patient, community and healthcare organisations. Participation was online, in-person or virtual.

Results

736 participants provided 2704 responses to the focal prompt. Unique concepts were summarised in 52 statements that were then rated by 271 participants. Participants rated the following three statements most highly as a gap that should be a priority for the health system to address (in rank order): ‘Not enough publicly funded home care services to meet the need’, ‘Home care support is not in place when arriving home from hospital’ and ‘Having to advocate to get enough home care’. The top priority was consistent across multiple subgroups.

Conclusions

In a country with universal health insurance, patients and caregivers from diverse backgrounds consistently prioritised insufficient public coverage for home care services as a gap the health system should address to improve the transition from hospital to home.
Quadratic integrals of a multi-scalar cosmological model
Authors: Jamal Sameerah
Published: January 2020

In the context of Friedmann–Robertson–Walker (FRW) spacetime with zero spatial curvature, we consider a multi-scalar tensor cosmology model under the pretext of obtaining quadratic conservation laws. We propose two new interaction potentials of the scalar field. Integral to this task is the existence of dynamical Noether symmetries which are Lie–Bäcklund transformations of the physical system. Finally, analytical solutions of the field are found corresponding to each new model. In one of the models, we find that the scale factor mimics [Formula: see text]-cosmology in a special case.
Advances in Using Nanotechnology Structuring Approaches for Improving Food Packaging
Authors: Mei Lei , Wang Qin
Published: January 2020

Recent advances in food packaging materials largely rely on nanotechnology structuring. Owing to several unique properties of nanostructures that are lacking in their bulk forms, the incorporation of nanostructures into packaging materials has greatly improved the performance and enriched the functionalities of these materials. This review focuses on the functions and applications of widely studied nanostructures for developing novel food packaging materials. Nanostructures that offer antimicrobial activity, enhance mechanical and barrier properties, and monitor food product freshness are discussed and compared. Furthermore, the safety and potential toxicity of nanostructures in food products are evaluated by summarizing the migration activity of nanostructures to different food systems and discussing the metabolism of nanostructures at the cellular level and in animal models.