bluuebunny/crossref_metadata_2025 huggingface dataset:
A single amino acid substitution in the transmembrane envelope glycoprotein of feline immunodeficiency virus alters cellular tropism
Authors: Vahlenkamp T W , Verschoor E J , Schuurman N N , van Vliet A L , Horzinek M C , Egberink H F , de Ronde A
Published: January 2020

The cellular tropism of the feline immunodeficiency virus (FIV) is affected by changes in variable region 3 (V3) of the surface (SU) envelope glycoprotein (Verschoor, E. J., et al., J. Virol. 69:4752-4757, 1995). By using high-dose DNA transfection, an FIV molecular clone with a non-CRFK-tropic V3 acquired the ability to replicate in CRFK cells. A single point mutation from a methionine to a threonine in the ectodomain of its transmembrane (TM) envelope glycoprotein was responsible for this change in viral tropism. This substitution is located in the putative SU interactive region, between the fusion peptide and the membrane-spanning region. Our results show that this region of the TM envelope glycoprotein constitutes an additional determinant for cell tropism.
Selective employment of chemokine receptors as human immunodeficiency virus type 1 coreceptors determined by individual amino acids within the envelope V3 loop
Authors: Speck R F , Wehrly K , Platt E J , Atchison R E , Charo I F , Kabat D , Chesebro B , Goldsmith M A
Published: January 2020

The chemokine receptor CCR5 acts as an essential cofactor for cell entry by macrophage-tropic human immunodeficiency virus type 1 (HIV-1) strains, whereas CXCR4 acts as an essential cofactor for T-cell-line-adapted strains. We demonstrated that the specific amino acids in the V3 loop of the HIV-1 envelope protein that determine cellular tropism also regulate chemokine coreceptor preference for cell entry by the virus. Further, a strong correlation was found between HIV-1 strains classified as syncytium inducing in standard assays and those using CXCR4 as a coreceptor. These data support the hypothesis that progressive adaptation to additional coreceptors is a key molecular basis for HIV-1 phenotypic evolution in vivo.
Deoxyribonucleic Acid Polymerase(s) of Rous Sarcoma Virus: Effects of Virion-Associated Endonuclease on the Enzymatic Product
Authors: Quintrell Nancy , Fanshier Lois , Evans Barbara , Levinson Warren , Bishop J. Michael
Published: January 2020

Purified preparations of Rous sarcoma virus (RSV) contain ribonuclease which is either a constituent of the virion surface or an adsorbed contaminant. Treatment of the virus with nonionic detergent to activate ribonucleic acid (RNA)-dependent deoxyribonucleic acid (DNA) polymerase renders the viral genome susceptible to hydrolysis by the external ribonuclease. The extent of this susceptibility can be substantially reduced by the use of limited amounts of detergent. At a concentration of detergent which provides a maximum initial rate of DNA synthesis, the degradation of endogenous viral RNA results in a reduced yield of high molecular weight DNA: RNA hybrid from the polymerase reaction. Attempts to detect virion-associated deoxyribonuclease, by using a variety of double helical DNA species as substrates, have been unsuccessful, but small amounts of nuclease activity directed against single-stranded DNA may be present in purified virus.
Size, Composition, and Structure of the Deoxyribonucleic Acid of Herpes Simplex Virus Subtypes 1 and 2
Authors: Kieff Elliott D. , Bachenheimer Steven L. , Roizman Bernard
Published: January 2020

Studies of the size, composition, and structure of the deoxyribonucleic acid (DNA) of the F and G prototypes of herpes simplex virus (HSV) subtypes 1 and 2 (HSV-1 and HSV-2) showed the following. (i) As previously reported by Good-heart et al. HSV-1 and HSV-2 DNA have a buoyant density of 1.726 and 1.728 g/cm
3
, corresponding to 67 and 69 guanine ± cytosine moles per cent, respectively. The difference in guanine plus cytosine content of the DNA species was confirmed by the finding of a 1 C difference in T
m
. (ii) The DNA from purified virus on cocentrifugation with T4 DNA in neutral sucrose density gradients sedimented at 55
S
, corresponding to 99 ± 5 million daltons in molecular weight. HSV-1 and HSV-2 DNA could not be differentiated with respect to size. (iii) Cosedimentation of alkali-denatured DNA from purified virus with T4 DNA on alkaline sucrose density gradients consistently yielded several bands of single-stranded HSV DNA ranging from fragments 7 × 10
6
daltons to intact strands 48 × 10
6
daltons in molecular weight.
Defective Particles in BHK Cells Infected with Temperature-Sensitive Mutants of Vesicular Stomatitis Virus
Authors: Reichmann M. E. , Pringle C. R. , Follett E. A. C.
Published: January 2020

Defective particles were the major product after undiluted passage of certain temperature-sensitive (
ts
) mutants of the Indiana C strain of vesicular stomatitis virus in BHK-21 cells at the permissive temperature (31 C). Essentially homogeneous preparations of defective particles were obtained with the wild-type and individual
ts
mutants. The defective particles associated with some of the
ts
mutants, however, were morphologically and physically distinguishable from wild type and from each other. All varieties of defective particle interfered with the multiplication of mutant and wild-type virus at the permissive temperature at early times of infection but failed to complement virions of different complementation groups at the restrictive temperature (39 C) at any time during infection.
Ribonucleic Acid Transcriptases in Sendai Virions and Infected Cells
Authors: Stone Henry O. , Portner Allen , Kingsbury D. W.
Published: January 2020

Sendai virions contain an enzyme which catalyzes the incorporation of ribonucleotides into ribonucleic acid (RNA). Enzyme activity was optimal at
p
H 8.0 and 28 C; otherwise conditions were similar to those reported for Newcastle disease virion (NDV) RNA polymerase. The initial rate of RNA synthesis by the Sendai virion enzyme was about 10 pmoles per mg of protein per hr, but after 3 hr of incubation the rate increased about fivefold. The virion enzyme was compared with an RNA polymerase in the microsomal fraction of infected cells. Both enzymes made predominantly single-stranded RNA which was complementary in base sequences to 50
S
virion RNA. Most of the RNA synthesized by the virion polymerase sedimented at 16
S
, but the product of the microsomal enzyme sedimented at about 8
S
.
Nucleoprotein Complexes in Simian Virus 40-Infected Cells
Authors: White Martin , Eason Robert
Published: January 2020

When African green monkey kidney cells (BSC-1) were infected with simian virus 40 (SV40) and extracted with 0.25% Triton X-100 after exposure to
3
H-thymidine, the
3
H-SV40 deoxyribonucleic acid (DNA) was present in a form which had a sedimentation coefficient in sucrose gradients of 44
S
. The change from the sedimentation coefficient of purified SV40 DNA (21
S
) was shown to result from the association of the SV40 DNA in the Triton extracts with protein by means of sensitivity to Pronase digestion and labeling with
14
C-amino acids. Short-term labeling experiments with
3
H-thymidine demonstrated that SV40 DNA molecules in the course of replication (25
S
) were also present as nucleoprotein complexes in Triton-extracted material. Labeled DNA extracted with Triton in the form of nucleoprotein complexes was obtained in amounts which were quantitatively equivalent to the amounts extracted with deoxycholate in parallel experiments. This indicated that the newly synthesized pools of SV40 DNA may not occur as free DNA in the infected cell.
Occurrence of Lysophosphatides in Bacteriophage T4rII-Infected
Escherichia coli
S/6
Authors: Bradley W. E. C. , Astrachan L.
Published: January 2020

Hydrolysis of phospholipids was observed to start about 15 min after
Escherichia coli
S/6 cells were infected with T4rII bacteriophage mutants. Hydrolysis continued through the latent period and well past the time when cell lysis occurs. The hydrolytic products that accumulated were free fatty acids, 2-acyl lysophosphatidylethanolamine, and various lysocardiolipins. These products indicated the action of phospholipase A
1
. From 15 to 22 min after infection, there were equivalent amounts of fatty acids and lysophosphatides in extracts of cellular lipids. Thereafter, free fatty acids were produced in excess. This suggests that lysophospholipase was active at the later time. We also observed a stoichiometric relation between loss of phosphatidylglycerol and increase of cardiolipin plus lysocardiolipins. This continued well past the normal lysis time (25 min). The appearance of lipase activities during the latent period seems to be specific to infection with rII mutants. Neither the wild-type bacteriophage nor rI mutants produced similar activities by 22 min after infection.
Isolation and Characterization of a Herpesvirus from Leukemic Guinea Pigs
Authors: Nayak D. P.
Published: January 2020

A guinea pig herpesvirus (GPHV) has consistently been isolated from leukemic lymphoblasts of strain-2 guinea pigs. GPHV is serologically related to the guinea pig herpes-like virus isolated by Hsiung and Kaplow. The virions of GPHV consist of an icosahedral capsid containing a dense nucleoprotein core enclosed in a double-layered membrane. The average diameters of GPHV virion and capsid were 166 and 101 nm, respectively. Studies on the morphogenesis of GPHV revealed that, as in other herpesvirus infections, only the naked capsids with or without the nucleoprotein core were found in the infected cell nuclei; it was also learned that the virion acquired its envelope by budding from the nuclear membrane of the infected cells. However, GPHV-infected cell nuclei also contained dense fibrous rods, resembling nucleo-protein core outside the capsids, and tubules resembling viral core protein. The capsids were often embedded in dense granular antigen. GPHV deoxyribonucleic acid (DNA) has a density of 1.716 g/ml in cesium chloride compared to herpes simplex virus DNA (ρ = 1.728 g/ml) and cellular DNA (ρ = 1.700 g/ml).
Herpes Simplex Virus: Genome Size and Redundancy Studied by Renaturation Kinetics
Authors: Frenkel Niza , Roizman Bernard
Published: January 2020

Herpes simplex virus subtype 1 deoxyribonucleic acid (DNA) was sheared in a French press to uniform fragments, denatured by heating, then allowed to reassociate. The renaturation reaction followed second-order kinetics with a single rate constant indicating that at least 95% of the genome was unique and that repetitive sequences, if present, were not detectable by this technique. The kinetic complexity of the herpes simplex genome was determined by DNA renaturation kinetics to be (95 ± 1) × 10
6
daltons. Since this value is in excellent agreement with the molecular weight of viral DNA [(99 ± 5) × 10
6
daltons] obtained from velocity sedimentation studies, it is concluded that virions contain only one species of double-stranded DNA molecules 95 × 10
6
to 99 × 10
6
daltons in molecular weight.
Structural Proteins of Adenovirus-Associated Viruses
Authors: Rose J. A. , Maizel J. V. , Inman J. K. , Shatkin A. J.
Published: January 2020

The structural proteins of adenovirus-associated virus (AAV) types 1, 2, and 3 were analyzed by acrylamide gel electrophoresis. In each case, one major protein (C) and two minor proteins (A and B) were identified. Component C had an estimated molecular weight of 62,000 daltons, and the molecular weights of components A and B were found to be 87,000 and 73,000 daltons, respectively. Coelectrophoresis of adenovirus and AAV proteins revealed an overlap only between the adenovirus fiber-penton component and the AAV C polypeptide. Among AAV serotypes, homologous components were electrophoretically identical, except that the C component of AAV-2 was of slightly lower molecular weight than the C components of AAV-1 and AAV-3. The relative incorporation of
14
C-arginine and
14
C-mixed amino acids into the three polypeptides of AAV-2 was similar, indicating an absence of an arginine-rich component. In addition, AAV-2 was found to have a substantially lower arginine content than helper adenoviruses.
Adenovirus-Associated Virus Multiplication
Authors: Rose J. A. , Koczot F.
Published: January 2020

The two complementary strand species of 5-bromodeoxyuridine-substituted, adenovirus-associated virus type 2 (AAV-2) deoxyribonucleic acid were preparatively separated in CsCl density gradients and further purified by sedimentation through 5 to 20% sucrose. The base composition of each strand species was determined, and it was found that the species banding at a greater density in CsCl (heavy strands) had an expected higher thymidine content (26.5%) than that 21.7%) of the less dense species (light strands). Furthermore, the base composition of in vivo-synthesized, AAV-specific ribonucleic acid was similar to that of light-strand deoxyribonucleic acid, and this ribonucleic acid apparently hybridized only with heavy strands. These observations indicate that the heavy-strand species alone serves as the transcriptional template in vivo. This study represents the first instance in which the base composition and specificity of in vivo transcription have been determined for each of the complementary strands of an animal virus deoxyribonucleic acid.
Electron Microscopy of Friend Murine Leukemia Virus in the Mid-Gut of Experimentally Infected Mosquitoes
Authors: Hirumi Hiroyuki , Burton George J. , Maramorosch Karl
Published: January 2020

After 30 and 78 hr, Friend murine leukemia virus (FLV) particles were detected by electron microscopy in the mid-gut lumen of the mosquitoes
Aedes aegypti
(Linnaeus) and
Anopheles stephensi
Liston which had fed on leukemia BALB/c mice infected with FLV. Various developmental stages of the virions were observed within and on the surface of ingested blood cells, particularly young erythroblasts, as well as free in the lumen after budding. These preliminary findings indicate that FLV continues to multiply in the mid-gut of these species for at least 3 days despite the action of digestive enzymes. Detailed studies are in progress to determine the fate of FLV in these mosquito species.
Separation of Reticuloendotheliosis Virus from Avian Tumor Viruses
Authors: Maldonado R. L. , Bose H. R.
Published: January 2020

Velocity sedimentation and isopycnic density gradient centrifugation indicate that reticuloendotheliosis virus has a different mass and buoyant density than members of the avian tumor virus group. The group-specific antigen of the avian tumor virus group was not detected in concentrated and purified reticuloendotheliosis virus preparations.
Structure and Development of Viruses as Observed in the Electron Microscope
Authors: Miyamoto Kaneatsu , Morgan Councilman
Published: January 2020

Two morphologically distinct types of capsids are described. The dense capsid appeared to be disrupted near the cellular membrane with release of core material. The light capsid was more stable and was frequently encountered close to the nucleus, where empty capsids were also found. Pretreatment of cells before infection with either puromycin or actinomycin D markedly decreased the percentage of empty capsids. It is suggested that the two types of capsids play different roles in the process of initiating infection. One (the dense capsid) releases deoxyribonucleic acid (DNA) shortly after entry. This DNA is transcribed into a virus-specific ribonucleic acid, which codes for an enzyme capable of altering the permeability of the second type of capsid (the light capsid). In proximity to the nucleus, the infectious DNA then escapes without gross disruption of the capsid.
Reovirus-Specific Ribonucleic Acid from Polysomes of Infected L Cells
Authors: Ward R. , Banerjee A. K. , LaFiandra A. , Shatkin A. J.
Published: January 2020

Polysomes from reovirus-infected L cells were analyzed. Although all 10 transcription products of the viral genome were represented in polysomes and presumably can be translated, fewer than 10 reovirus-specific polypeptides were detected in infected cells. The 5′-terminal sequence of all species of reovirus ribonucleic acid (RNA) from polysomes was ppGpYp, as previously found for the genome double-stranded RNA and the in vitro single-stranded products of the virion-associated RNA polymerase. RNA isolated from both heavy (>30 ribosomes) and light (5 to 8 ribosomes) polysomes includes similar amounts of large, medium, and small classes of reovirus single-stranded RNA, suggesting that linkage of the genome segments observed in virions may occur at the single-strand stage of RNA replication.
Isolation of ΦX174 Specific Messenger Ribonucleic Acids In Vivo and Identification of Their 5′ Terminal Nucleotides
Authors: Hayashi Marie N. , Hayashi Masaki
Published: January 2020

Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) hybridization in formamide at low temperature was applied to hybridization of ΦX174 replicative form DNA and in vivo ΦX174 specific messenger RNA (mRNA) with some modification. We found that ΦX174 mRNA up to molecular weight 1.2 × 10
6
could be hybridized to and eluted from DNA without apparent breakage of phosphodiester bonds and the 5′ terminal guanosine triphosphate and adenosine triphosphate of the RNA. By alkali hydrolysis of the purified in vivo ΦX174 mRNA and subsequent thin-layer chromatography of the digest, we isolated the 5′ terminal nucleotides and identified them as 2′- or 3′-monophosphate guanosine 5′-triphosphate (pppGp) and 2′- or 3′-monophosphate adenosine 5′-triphosphate (pppAp). By comparing the in vitro and in vivo synthesized ΦX174 mRNA, a difference in the pppAp-pppGp ratio was observed. In the in vitro RNA, this ratio was 1.5, whereas in the in vivo RNA it was 5.5.
Mechanism of Antiviral Action of Acetone on Rabbitpox Virus Replication
Authors: Chernos V. I. , Libshits B. A. , Yakobson E. , Ghendon Y. Z.
Published: January 2020

Acetone added to the maintenance medium in a 1% concentration reduces the yield of infectious rabbitpox virus in L-cell monolayer cultures by 90 to 97%. This concentration of the inhibitor is not toxic for cells. It was established that there is an inhibitor-sensitive stage late in the infectious cycle. Acetone exerted no significant influence on production of early viral messenger ribonucleic acid, formation of polyribosomes, deoxyribonucleic acid (DNA) replication, or protein synthesis. In the presence of acetone, the assembly of so-called “acetone particles” occurred. These particles are similar to normal virions by morphological and sedimentation properties but are slightly different from them in buoyant density. The amount of virus-specific DNA and the optical density of the “acetone particles” are the same as those of normal virions despite a 10- to 25-fold difference in the infectivity of the preparations.
Transduction of Gal
+
by Coliphage T1 I. Role of Hybrids of Bacterial and Prophage λ Deoxyribonucleic Acid
Authors: Drexler Henry
Published: January 2020

Hybrids of λ and adjacent bacterial deoxyribonucleic acid carried in T1 particles were able to transduce Gal
+
with a greatly increased efficiency to strains which were not immune to λ compared to immune strains. The enhanced transduction was dependent on a functional
recA
+
gene in the recipient. Mutations of the donor's λ prophage which abolished the function of either the cI, O, or P genes in the recipients led to a further enhancement of transduction. The rate of transduction of a nonlysogenic recipient such as W3350 by the hybrid particles may be as much as 140 times greater than transduction of the lysogenic recipient W3350(λ). In addition to the effect of λ immunity in blocking enhanced transduction, mutations of the N gene of the donor's λ prophage abolished enhanced transduction. Mutations in the
red, int, xis
, and Q genes of the donor's prophage had no significant effect on transduction. The hybrids which mediated the enhanced transduction are called (λ-
gal
)T1.
Chromatographic Separation and Antigenic Analysis of Proteins of the Oncornaviruses II. Mammalian Leukemia-Sarcoma Viruses
Authors: Nowinski Robert C. , Fleissner Erwin , Sarkar Nurul H. , Aoki Tadao
Published: January 2020

Proteins of leukemia and sarcoma viruses from the chicken, mouse, hamster, and cat were analyzed by gel filtration in guanidine hydrochloride. The mammalian viruses were found to contain six major proteins, whereas the avian viruses contained seven proteins. Proteins of viruses from different mammalian species had the same molecular weights which also closely resembled the molecular weights of the six equivalent avian viral proteins. These results defined a basic similarity in protein composition for the C-type viruses of avian and mammalian origin. The two glyco-proteins of murine leukemia virus were identified immunologically as constituents of the viral membrane. Antisera prepared against other proteins distinguished individual internal viral antigens in immunodiffusion tests and also reacted in immunofluorescence with cytoplasmic components of infected cells. Antisera which reacted with the major internal viral proteins did not contain antibodies inhibitory to the viral reverse transcriptase.
Separation of Two Types of Adeno-Associated Virus Particles Containing Complementary Polynucleotide Chains
Authors: Berns K. I. , Adler S.
Published: January 2020

An adeno-associated virus containing bromodeoxyuridine-substituted deoxyribonucleic acid has been fractionated by equilibrium centrifugation in CsCl into two classes of virions which contain complementary polynucleotide chains.
Identification and Genetic Characterization of Mutants of Bacteriophage T4 Defective in the Ability to Induce Exonuclease A
Authors: Warner Huber R. , Snustad D. Peter , Koerner James F. , Childs J. D.
Published: January 2020

A mutant of bacteriophage T4 unable to induce exonuclease A has been isolated. The mutation responsible for this defect maps between genes 39 and 56, in a region of the chromosome devoid of other known markers. Four deletion mutants lacking part of the genome located between genes 39 and 56 also fail to induce exonuclease A. The ability of all of these mutants to replicate suggests that exonuclease A is not essential for replication of phage T4.
Polyamines in the Synthesis of Bacteriophage Deoxyribonucleic Acid. I. Lack of Dependence of Polyamine Synthesis on Bacteriophage Deoxyribonucleic Acid Synthesis
Authors: Dion Arnold S. , Cohen Seymour S.
Published: January 2020

To determine whether polyamine synthesis is dependent on deoxyribonucleic acid (DNA) synthesis, polyamine levels were estimated after infection of bacterial cells with ultraviolet-irradiated T4 or T4
am
N 122, a DNA-negative mutant. Although phage DNA accumulation was restricted to various degrees in comparison to cells infected with T4D, nearly commensurate levels of putrescine and spermidine synthesis were observed after infection, regardless of the rate of phage DNA synthesis. We conclude from these data that polyamine synthesis after infection is independent of phage DNA synthesis.
Contact-Inhibited Revertant Cell Lines Isolated from Simian Virus 40-Transformed Cells III. Concanavalin A-Selected Revertant Cells
Authors: Culp Lloyd A. , Black Paul H.
Published: January 2020

Contact-inhibited variants have been isolated by treatment of simian virus 40 (SV40)-transformed Balb/c 3T3 cells (SVT2) with the plant lectin concanavalin A. These con A revertant cells exhibit the following properties: (i) they resemble 3T3 cells morphologically and grow to saturation densities which are similar to that of 3T3 cells; (ii) they synthesize the SV40-specific T antigen and yield infectious virus after fusion with permissive monkey cells; (iii) they contain a high sialic acid content similar to that of 3T3 cells and not to that of SVT2 cells; sialic acid composition was found to be independent of serum concentration; (iv) they contain more chromosomes with the average number in the tetraploid range than the SVT2 cells from which they were derived; and (v) SVT2 and revertant cells, confluent or subconfluent, produce more collagen than Balb/3T3 cells. The relationship of surface membrane properties to contact inhibition of growth and the mechanisms for generating revertant cells are discussed.
Genetic Relatedness of Type 1 and Type 2 Herpes Simplex Viruses
Authors: Kieff Elliott , Hoyer Bill , Bachenheimer Steven , Roizman Bernard
Published: January 2020

The extent of homology between herpes simplex virus
1
and
2
(HSV-1 and HSV-2) deoxyribonucleic acid (DNA) was measured in two ways: (i) by determination of the relative rate of hybridization of labeled HSV-1 and HSV-2 DNA to excess unlabeled HSV-1 or HSV-2 DNA immobilized on filters and (ii) by determination of the rate of hybridization of labeled HSV-1 and HSV-2 DNA to excess unlabeled HSV-1 or HSV-2 DNA in solution. Approximately 40% of HSV-1 and HSV-2 DNA is homologous at hybridization temperatures 25 C below the melting temperature (T
m
) of HSV DNA (liquid-filter annealing). Lowering the temperature to 34 C below the T
m
increased the extent of homology to 46% (liquid annealing). The extent of base-pairing in HSV-1-HSV-2 heteroduplex DNA was determined by thermal chromatography on hydroxyapatite. Heteroduplexes of HSV-1 and HSV-2 DNA eluted in a single peak whose midpoint (Te
50
) was 10 C below that of the homoduplex. Conspicuously absent were heteroduplexes that eluted at more than 15 C below the Te
50
of the homoduplex. The data indicate the existence of a variable region of DNA (54%) with very little, if any, homology and an invariable region (46%) with relatively good (85%) matching of base pairs.
Incorporation of L Cell Sterols into Vesicular Stomatitis Virus
Authors: Bates Sandra R. , Rothblat George H.
Published: January 2020

The incorporation of host cell sterol into vesicular stomatitis virus can be effectively studied in an L cell system. The end product of de novo sterol synthesis in the L cell is desmosterol, and as the concentration of cholesterol in the medium is increased the cells incorporate the exogenous cholesterol and the synthesis of desmosterol decreases. L cells which contained desmosterol as their sole sterol produced virus whose sterol content was similarly composed of only desmosterol. Virus grown in L cells which had a constantly changing sterol ratio also contained a mixture of cholesterol and desmosterol, but the virus was found to be more enriched in cholesterol than in the L cells in which it was grown. Viral stability, growth, and plaquing efficiency were tested and found not to be affected by the alteration of its sterol composition, i.e., by partially or completely replacing cholesterol with desmosterol.
Genetic Analysis of Simian Virus 40 IV. Inhibited Transformation of Balb/3T3 Cells by a Temperature-Sensitive Early Mutant
Authors: Robb James A. , Smith Helene S. , Scher Charles D.
Published: January 2020

The temperature-sensitive early mutant,
ts
*
101
, was characterized during productive infection in monkey cells, and the results are presented in an accompanying paper. This paper demonstrates that although
101
mutant virions adsorb normally to confluent Balb/3T3 mouse cells at both permissive (33 C) and restrictive (38.5 C) temperatures, T antigen synthesis and transformation, abortive and stable, are inhibited at both temperatures (host-range inhibition). T antigen synthesis is temperature sensitive, whereas abortive and stable transformation are not. Clones of
101
-transformed Balb/3T3 cells were isolated, and virus was rescued from all clones at both permissive and restrictive temperatures. The rescued virus was as temperature sensitive as the original transforming
101
virions.
TpiA is a Key Metabolic Enzyme That Affects Virulence and Resistance to Aminoglycoside Antibiotics through CrcZ in Pseudomonas aeruginosa
Authors: Xia Yushan , Wang Dan , Pan Xiaolei , Xia Bin , Weng Yuding , Long Yuqing , Ren Huan , Zhou Jingyi , Jin Yongxin , Bai Fang , Cheng Zhihui , Jin Shouguang , Wu Weihui
Published: January 2020

The increase in bacterial resistance against antibiotics imposes a severe threat to public health. It is urgent to identify new drug targets and develop novel antimicrobials. Metabolic homeostasis of bacteria plays an essential role in their virulence and resistance to antibiotics. Recent studies demonstrated that antibiotic efficacies can be improved by modulating the bacterial metabolism.
Pseudomonas aeruginosa
is an important opportunistic human pathogen that causes various infections. The bacterium is intrinsically resistant to antibiotics. In this study, we provide clear evidence that TpiA (triosephosphate isomerase) plays an essential role in the metabolism of
P. aeruginosa
and influences bacterial virulence and antibiotic resistance. The significance of this work is in identifying a key enzyme in the metabolic network, which will provide clues as to the development of novel treatment strategies against infections caused by
P. aeruginosa
.
Diversification of Campylobacter jejuni Flagellar C-Ring Composition Impacts Its Structure and Function in Motility, Flagellar Assembly, and Cellular Processes
Authors: Henderson Louie D. , Matthews-Palmer Teige R. S. , Gulbronson Connor J. , Ribardo Deborah A. , Beeby Morgan , Hendrixson David R.
Published: January 2020

The conserved core of bacterial flagellar motors reflects a shared evolutionary history that preserves the mechanisms essential for flagellar assembly, rotation, and directional switching. In this work, we describe an expanded and diversified set of core components in the
Campylobacter jejuni
flagellar C ring, the mechanistic core of the motor. Our work provides insight into how usually conserved core components may have diversified by gene duplication, enabling a division of labor of the ancestral protein between the two new proteins, acquisition of new roles in flagellar assembly and motility, and expansion of the function of the flagellum beyond motility, including spatial regulation of cell division and numerical control of flagellar biogenesis in
C. jejuni
. Our results highlight that relatively small changes, such as gene duplications, can have substantial ramifications on the cellular roles of a molecular machine.
CARD9 Is Required for Classical Macrophage Activation and the Induction of Protective Immunity against Pulmonary Cryptococcosis
Authors: Campuzano Althea , Castro-Lopez Natalia , Martinez Amanda J. , Olszewski Michal A. , Ganguly Anutosh , Leopold Wager Chrissy , Hung Chiung-Yu , Wormley Floyd L.
Published: January 2020

Cryptococcus neoformans
is a fungal pathogen that is found throughout the environment and can cause life-threatening infections of the lung and central nervous system in severely immunocompromised individuals. Caspase recruitment domain-containing protein 9 (CARD9) is a critical molecule that is activated after interactions of C-type lectin receptors (CLRs) found on the surfaces of specific immune cells, with carbohydrate structures associated with fungi. Patients with defects in CARD9 are significantly more susceptible to a multitude of fungal infections.
C. neoformans
contains several carbohydrate structures that interact with CLRs on immune cells and activate CARD9. Consequently, these studies evaluated the necessity of CARD9 for the induction of protective immunity against
C. neoformans
infection. These results are important, as they advance our understanding of cryptococcal pathogenesis and host factors necessary for the induction of protective immunity against
C. neoformans
.
Dynamic Characterization of Protein and Posttranslational Modification Levels in Mycobacterial Cholesterol Catabolism
Authors: Xu Jun-Yu , Zhao Lei , Xu Ying , Li Bolin , Zhai Linhui , Tan Minjia , Ye Bang-Ce
Published: January 2020

Cholesterol assimilation is a critical step in mycobacterial chronic infection. However, knowledge from the dynamic characterization of cholesterol metabolism in mycobacteria at the protein expression and PTM levels remains limited. Our study uncovered the landscape of protein expression, lysine acetylation, lysine propionylation, and S/T/Y phosphorylation during the metabolic changes from glucose to cholesterol in mycobacteria. The data showed that cholesterol-induced carbon shift resulted in the elevation of protein expression and lysine acylation in diverse metabolic enzymes involved in cholesterol degradation and that the presence of cholesterol also promoted the perturbations at the phosphorylation level in the kinase system in mycobacteria. This study systematically characterized the regulation of cholesterol catabolism at several different levels, which provided the detailed references in mycobacterial proteome and potential antimycobacterial strategies.
Rail surfacing repairing technique with self-shielded flux-cored wires
Authors: Chen Jia , Gou Guoqing , Zhu Zhongyin , Gao Wei
Published: January 2020

A newly self-protecting flux-cored wire was used for simulated U75V rail repairing and five welding process parameters were applied. The influence of welding parameter on the hardness and microstructure of the wire and solder layers was investigated. The single-pass welding process with different preheating parameters and post-treatment parameters were also taken into research. The results showed that the welding process parameters have a significant influence on the weld quality, and mismatched parameters will increase the welding defects. The number of welding layers has a great influence on the hardness and structure. Increasing preheating temperature and a post-heat treatment at a high-temperature can enhance the hardening effect.
Optimizations in C++ Compilers
Authors: Godbolt Matt
Published: January 2020

There’s a tradeoff to be made in giving the compiler more information: it can make compilation slower. Technologies such as link time optimization can give you the best of both worlds. Optimizations in compilers continue to improve, and upcoming improvements in indirect calls and virtual function dispatch might soon lead to even faster polymorphism.
Space Time Discontinuum
Authors: Helland Pat
Published: January 2020

Back when you had only one database for an application to worry about, you didn’t have to think about partial results. You also didn’t have to think about data arriving after some other data. It was all simply there. Now, you can do so much more with big distributed systems, but you have to be more sophisticated in the tradeoff between timely answers and complete answers.
The Geology and Biogeochemistry of Hydrocarbon Seeps
Authors: Joye Samantha B.
Published: January 2020

Hydrocarbon seeps, deep sea extreme environments where deeply sourced fluids discharge at the seabed, occur along continental margins across the globe. Energy-rich reduced substrates, namely hydrocarbons, support accelerated biogeochemical dynamics, creating unique geobiological habitats. Subseafloor geology dictates the surficial expression of seeps, generating hydrocarbon (gas and/or oil) seeps, brine seeps, and mud volcanoes. Biogeochemical processes across the redox spectrum are amplified at hydrocarbon seeps due to the abundance and diversity of reductant; anaerobic metabolism dominates within the sediment column since oxygen is consumed rapidly near the sediment surface. Microbial activity is constrained by electron acceptor availability, with rapid recycling required to support observed rates of hydrocarbon consumption. Geobiologic structures, from gas hydrate to solid asphalt to authigenic minerals, form as a result of hydrocarbon and associated fluid discharge. Animal-microbial associations and symbioses thrive at hydrocarbon seeps, generating diverse and dense deep sea oases that provide nutrition to mobile predators. ▪  Hydrocarbon seeps are abundant deep sea oases that support immense biodiversity and where specialization and adaptation create extraordinary lifestyles. ▪  Subseafloor geology shapes and defines the geochemical nature of fluid seepage and regulates the flux regime, which dictate the surface expression. ▪  High rates of anaerobic oxidation of methane require coupling to multiple processes and promote diversity in the anaerobic methanotroph microbial community. ▪  The recent discovery of novel phyla possessing hydrocarbon oxidation potential signals that aspects of seep biogeochemistry and geobiology remain to be discovered.
Functional Foods: Product Development, Technological Trends, Efficacy Testing, and Safety
Authors: Granato Daniel , Barba Francisco J. , Bursać Kovačević Danijela , Lorenzo José M. , Cruz Adriano G. , Putnik Predrag
Published: January 2020

Functional foods is a very popular term in the social and scientific media; consequently, food producers have invested resources in the development of processed foods that may provide added functional benefits to consumers’ well-being. Because of intrinsic regulation and end-of-use purposes in different countries, worldwide meanings and definitions of this term are still unclear. Hence, here we standardize this definition and propose a guideline to attest that some ingredients or foods truly deserve this special designation. Furthermore, focus is directed at the most recent studies and practical guidelines that can be used to develop and test the efficacy of potentially functional foods and ingredients. The most widespread functional ingredients, such as polyunsaturated fatty acids (PUFAs), probiotics/prebiotics/synbiotics, and antioxidants, and their technological means of delivery in food products are described. The review discusses the steps that food companies should take to ensure that their developed food product is truly functional.
Recent Advances in Recombinant Protein Production by Bacillus subtilis
Authors: Zhang Kang , Su Lingqia , Wu Jing
Published: January 2020

Bacillus subtilis has become a widely used microbial cell factory for the production of recombinant proteins, especially those associated with foods and food processing. Recent advances in genetic manipulation and proteomic analysis have been used to greatly improve protein production in B. subtilis. This review begins with a discussion of genome-editing technologies and application of the CRISPR–Cas9 system to B. subtilis. A summary of the characteristics of crucial legacy strains is followed by suggestions regarding the choice of origin strain for genetic manipulation. Finally, the review analyzes the genes and operons of B. subtilis that are important for the production of secretory proteins and provides suggestions and examples of how they can be altered to improve protein production. This review is intended to promote the engineering of this valuable microbial cell factory for better recombinant protein production.
Noncoding RNAs in Vascular Aging
Authors: Cao Qidong , Wu Jiuping , Wang Xiaoli , Song Chunli
Published: January 2020

Increases in age are accompanied by vascular aging, which can lead to a variety of chronic diseases, including atherosclerosis and hypertension. Noncoding RNAs (ncRNAs) have become a research hotspot in different fields of life sciences in recent years. For example, these molecules have been found to have regulatory roles in many physiological and pathological processes. Many studies have shown that microRNAs (miRNAs) and long ncRNAs (lncRNAs) also play a regulatory role in vascular aging. Endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) are important components of blood vessels, and the senescence of both cell types promotes the occurrence of vascular aging. This review provides a contemporary update on the molecular mechanisms underlying the senescence of ECs and VSMCs and the regulatory role of miRNAs and lncRNAs in this process.
Inhibition of Mitochondrial ROS by MitoQ Alleviates White Matter Injury and Improves Outcomes after Intracerebral Haemorrhage in Mice
Authors: Chen Weixiang , Guo Chao , Jia Zhengcai , Wang Jie , Xia Min , Li Chengcheng , Li Mingxi , Yin Yi , Tang Xiaoqin , Chen Tunan , Hu Rong , Chen Yujie , Liu Xin , Feng Hua
Published: January 2020

White matter injury (WMI) is an important cause of high disability after intracerebral haemorrhage (ICH). It is widely accepted that reactive oxygen species (ROS) contributes to WMI, but there is still no evidence-based treatment. Here, mitoquinone (MitoQ), a newly developed selective mitochondrial ROS scavenger, was used to test its neuroprotective potential. The data showed that MitoQ attenuated motor function deficits and motor-evoked potential (MEP) latency prolongation. Further research found that MitoQ blunted the loss of oligodendrocytes and oligodendrocyte precursor cells, therefore reduced demyelination and axon swelling after ICH. In the in vitro experiments, MitoQ, but not the nonselective antioxidant, almost completely attenuated the iron-induced membrane potential decrease and cell death. Mechanistically, MitoQ blocked the ATP deletion and mitochondrial ROS overproduction. The present study demonstrates that the selective mitochondrial ROS scavenger MitoQ may improve the efficacy of antioxidant treatment of ICH by white matter injury alleviation.
Amplitude Modulated Noise for Tinnitus Suppression in Tonal and Noise-Like Tinnitus
Authors: Schoisswohl Stefan , Arnds Johannes , Schecklmann Martin , Langguth Berthold , Schlee Winfried , Neff Patrick
Published: January 2020

Background: The phenomenon of short-term tinnitus suppression by different forms of acoustic stimulation is referred to as residual inhibition (RI). RI can be triggered in the majority of tinnitus cases and was found to be depending on the used intensity, length or types of sounds. Past research already stressed the impact of noise stimulation as well as the superiority of amplitude modulated (AM) pure tones at the individual tinnitus frequency for RI in tonal tinnitus. Recently a novel approach for the determination of noise-like tinnitus characteristics was proposed. Objectives: The aim of the present study was to investigate whether in participants with noise-like tinnitus RI can be increased by AM noise stimuli according to the individual tinnitus frequency range. Methods: For this purpose the individual tinnitus characteristics (noise-like and tonal tinnitus) of 29 people affected by tinnitus (mean age = 55.59, 7 females, mean tinnitus duration = 159.97 months) were assessed via customizable noise-band matching. The objective was to generate bandpass filtered stimuli according to the individual tinnitus sound (individualized bandpass filtered [IBP] sounds). Subsequently, various stimuli differing in bandpass filtering and AM were tested with respect to their potential to induce RI. Participants were acoustically stimulated with 7 different types of stimuli for 3 min each and had to rate the loudness of their tinnitus after each stimuli. Results: Results indicate a general efficacy of noise stimuli for the temporary suppression of tinnitus, but no significant differences between AM and unmodulated IBP. Significantly better effects were observed for the subgroup with noise-like tinnitus (n = 14), especially directly after stimulation offset. Conclusions: The study at hand provides further insights in potential mechanisms behind RI for different types of tinnitus. Beyond that, derived principles may qualify for new or extend current tinnitus sound therapies.
Peptic Ulcer: Chapter Closed?
Authors: Malfertheiner Peter , Schulz Christian
Published: January 2020

The incidence of peptic ulcer disease (PUD) peaked in the late 19th century while transiting into the 20th century. With entry in the new millennium a significant decrease of PUD has occurred. However, demographic changes with an increasing elderly population associated with multiple comorbidities and polypharmacy became responsible for a persistent high rate of peptic ulcer complications. The acid driven concept of PUD has directed the development of surgical procedures and drugs with an increasing potency in acid suppression. High speed of symptom resolution and rapid ulcer healing was obtained with the introduction of proton pump inhibitors, but cure of PUD has failed. The arrival of Helicobacter pylori has revolutionized the history of PUD which has become a curable disease by successful cure of the infection. However, new challenges have emerged with an increase of treatment failures due to increasing antibiotic resistance of H. pylori. The changing pattern in the prevalence of etiologies other than H. pylori demands for accurate identification of the ulcerogenic cause in the individual patient to allow for proper selection of therapy. Management of peptic ulcer bleeding remains a critical clinical challenge. The chapter of PUD is reduced in size and has become more heterogeneous – but is not closed!
Enhanced CaMKII-Dependent Late I
Na
Induces Atrial Proarrhythmic Activity in Patients With Sleep-Disordered Breathing
Authors: Lebek Simon , Pichler Konstantin , Reuthner Kathrin , Trum Maximillian , Tafelmeier Maria , Mustroph Julian , Camboni Daniele , Rupprecht Leopold , Schmid Christof , Maier Lars S. , Arzt Michael , Wagner Stefan
Published: January 2020

Rationale:

Sleep-disordered breathing (SDB) is frequently associated with atrial arrhythmias. Increased CaMKII (Ca/calmodulin-dependent protein kinase II) activity has been previously implicated in atrial arrhythmogenesis.

Objective:

We hypothesized that CaMKII-dependent dysregulation of Na current (I
Na
) may contribute to atrial proarrhythmic activity in patients with SDB.

Methods and Results:

We prospectively enrolled 113 patients undergoing elective coronary artery bypass grafting for cross-sectional study and collected right atrial appendage biopsies. The presence of SDB (defined as apnea-hypopnea index ≥15/h) was assessed with a portable SDB monitor the night before surgery. Compared with 56 patients without SDB, patients with SDB (57) showed a significantly increased level of activated CaMKII. Patch clamp was used to measure I
Na
. There was a significantly enhanced late I
Na
, but reduced peak I
Na
due to enhanced steady-state inactivation in atrial myocytes of patients with SDB consistent with significantly increased CaMKII-dependent cardiac Na channel phosphorylation (Na
V
1.5, at serine 571, Western blotting). These gating changes could be fully reversed by acute CaMKII inhibition (AIP [autocamtide-2 related inhibitory peptide]). As a consequence, we observed significantly more cellular afterdepolarizations and more severe premature atrial contractions in atrial trabeculae of patients with SDB, which could be blocked by either AIP or KN93 (N-[2-[[[(E)-3-(4-chlorophenyl)prop-2-enyl]-methylamino]methyl]phenyl]-N-(2-hydroxyethyl)-4-methoxybenzenesulfonamide). In multivariable linear regression models incorporating age, sex, body mass index, existing atrial fibrillation, existing heart failure, diabetes mellitus, and creatinine levels, apnea-hypopnea index was independently associated with increased CaMKII activity, enhanced late I
Na
and correlated with premature atrial contraction severity.

Conclusions:

In atrial myocardium of patients with SDB, increased CaMKII-dependent phosphorylation of Na
V
1.5 results in dysregulation of I
Na
with proarrhythmic activity that was independent from preexisting comorbidities. Inhibition of CaMKII may be useful for prevention or treatment of arrhythmias in SDB.

Clinical Trial Registration:

URL:
http://www.clinicaltrials.gov
. Unique identifier: NCT02877745.

Visual Overview:

An online visual overview is available for this article.