bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication and characterization of novel monolayer InN quantum wells in a GaN matrix
Authors: Yoshikawa A. , Che S. B. , Hashimoto N. , Saito H. , Ishitani Y. , Wang X. Q.
Published: August 2008

The authors propose and demonstrate fine structure novel InN/GaN multiple quantum wells (MQWs) consisting of ultimately thin InN wells around 1 ML inserted in a GaN matrix grown under In-polarity growth regime by molecular beam epitaxy. Since the critical thickness of InN epitaxy on the c-plane GaN is about 1 ML and also the growth temperature for 1 ML InN insertion can be remarkably higher than conventional one, the proposed MQW structure can avoid new generation of misfit dislocation at the heterointerface, in principle, and results in high quality MQW structure due to the effects of enhanced surface migration at higher temperatures. It is shown that demonstrated 1 ML InN/GaN MQW structures indicate surprisingly higher structural quality/properties than those former-reported InN-based heterostructures. Self-ordering mechanism arising from immiscibility nature in between InN and GaN will also contribute for depositing sharp and atomically flat InN well. The proposed MQW structure has physically and practically important meanings leading to room temperature operating GaN-based excitonic devices and also efficient photonic devices working in short wavelength visible colors.
Synthesis of nitrogen passivated rare-earth doped hafnia thin films and high temperature electrochemical conduction studies
Authors: Ramanathan S. , Karthikeyan A. , Govindarajan S. A. , Kirsch P. D.
Published: August 2008

The authors report on the synthesis, electrical characterization, and high temperature electrochemical conductivity of nitrogen passivated crystalline rare-earth doped hafnia thin films with high-dielectric constant (∼30) and low leakage currents. High temperature electrochemical conductivity of the Re-doped nitrided hafnia thin films are comparable to one another. The results are of potential significance to synthesis of crystalline oxides on semiconductor surfaces with tailored functionality.
Spherical field emission cathode based on carbon nanotube paste and its application in luminescent bulbs
Authors: Fu Weiqi , Liu Peng , Tang Jie , Liu Liang , Fan Shoushan
Published: August 2008

The authors have developed a spherical field-emission cathode based on carbon nanotube paste. The cathode was formed on a 2mm stainless-steel ball with a silver paste sublayer which provide good adhesion between carbon nanotubes and the metal substrate. The emission current with a density of 300mA∕cm2 was obtained and the current showed good stability. The cathode was assembled into a luminescent lightbulb with 8kV anode voltage. The luminous efficiency was 26.4lm∕W on pulse mode.
Comment on "Protein Sequences from Mastodon and
Tyrannosaurus rex
Revealed by Mass Spectrometry"
Authors: Pevzner Pavel A. , Kim Sangtae , Ng Julio
Published: August 2008

Asara
et al
. (Reports, 13 April 2007, p. 280) reported sequencing of
Tyrannosaurus rex
proteins and used them to establish the evolutionary relationships between birds and dinosaurs. We argue that the reported
T. rex
peptides may represent statistical artifacts and call for complete data release to enable experimental and computational verification of their findings.
The Geological Evolution of the Tibetan Plateau
Authors: Royden Leigh H. , Burchfiel B. Clark , van der Hilst Robert D.
Published: August 2008

The geological evolution of the Tibetan plateau is best viewed in a context broader than the India-Eurasia collision zone. After collision about 50 million years ago, crust was shortened in western and central Tibet, while large fragments of lithosphere moved from the collision zone toward areas of trench rollback in the western Pacific and Indonesia. Cessation of rapid Pacific trench migration (∼15 to 20 million years ago) coincided with a slowing of fragment extrusion beyond the plateau and probably contributed to the onset of rapid surface uplift and crustal thickening in eastern Tibet. The latter appear to result from rapid eastward flow of the deep crust, probably within crustal channels imaged seismically beneath eastern Tibet. These events mark a transition to the modern structural system that currently accommodates deformation within Tibet.
Adenovirus Small e1a Alters Global Patterns of Histone Modification
Authors: Horwitz Gregory A. , Zhang Kangling , McBrian Matthew A. , Grunstein Michael , Kurdistani Siavash K. , Berk Arnold J.
Published: August 2008

Adenovirus small early region 1a (e1a) protein drives cells into S phase by binding RB family proteins and the closely related histone acetyl transferases p300 and CBP. The interaction with RB proteins displaces them from DNA-bound E2F transcription factors, reversing their repression of cell cycle genes. However, it has been unclear how the e1a interaction with p300 and CBP promotes passage through the cell cycle. We show that this interaction causes a threefold reduction in total cellular histone H3 lysine 18 acetylation (H3K18ac). CBP and p300 are required for acetylation at this site because their knockdown causes specific hypoacetylation at H3K18. SV40 T antigen also induces H3K18 hypoacetylation. Because global hypoacetylation at this site is observed in prostate carcinomas with poor prognosis, this suggests that processes resulting in global H3K18 hypoacetylation may be linked to oncogenic transformation.
Epigenetic Reprogramming by Adenovirus e1a
Authors: Ferrari Roberto , Pellegrini Matteo , Horwitz Gregory A. , Xie Wei , Berk Arnold J. , Kurdistani Siavash K.
Published: August 2008

Adenovirus e1a induces quiescent human cells to replicate. We found that e1a causes global relocalization of the RB (retinoblastoma) proteins (RB, p130, and p107) and p300/CBP histone acetyltransferases on promoters, the effect of which is to restrict the acetylation of histone 3 lysine-18 (H3K18ac) to a limited set of genes, thereby stimulating cell cycling and inhibiting antiviral responses and cellular differentiation. Soon after expression, e1a binds transiently to promoters of cell cycle and growth genes, causing enrichment of p300/CBP, PCAF (p300/CBP-associated factor), and H3K18ac; depletion of RB proteins; and transcriptional activation. e1a also associates transiently with promoters of antiviral genes, causing enrichment for RB, p130, and H4K16ac; increased nucleosome density; and transcriptional repression. At later times, e1a and p107 bind mainly to promoters of development and differentiation genes, repressing transcription. The temporal order of e1a binding requires its interactions with p300/CBP and RB proteins. Our data uncover a defined epigenetic reprogramming leading to cellular transformation.
A Polemic Against Control
Authors: Caldwell John C.
Published: August 2008

Fatal Misconception
. The Struggle to Control World Population.
By Matthew Connelly
. Belknap (Harvard University Press), Cambridge, MA, 2008. 537 pp. $35, £22.95, €24.50. ISBN 9780674024236.

A historian offers a sometimes angry and often critical account of 20th-century transnational efforts to limit population growth.
Cybernetic Birth Control
Authors: Mueggler Erik A.
Published: August 2008

Just One Child
. Science and Policy in Deng's China.
By Susan Greenhalgh
. University of California Press, Berkeley, 2008. 425 pp. $55, £32.95. ISBN 9780520253384. Paper, $21.95, £12.95. ISBN 9780520253391.

The author explores how in the late 1970s China's leadership decided to attempt to limit all couples to a single offspring.
Star Formation Around Supermassive Black Holes
Authors: Bonnell I. A. , Rice W. K. M.
Published: August 2008

The presence of young massive stars orbiting on eccentric rings within a few tenths of a parsec of the supermassive black hole in the galactic center is challenging for theories of star formation. The high tidal shear from the black hole should tear apart the molecular clouds that form stars elsewhere in the Galaxy, and transport of stars to the galactic center also appears unlikely during their lifetimes. We conducted numerical simulations of the infall of a giant molecular cloud that interacts with the black hole. The transfer of energy during closest approach allows part of the cloud to become bound to the black hole, forming an eccentric disk that quickly fragments to form stars. Compressional heating due to the black hole raises the temperature of the gas up to several hundred to several thousand kelvin, ensuring that the fragmentation produces relatively high stellar masses. These stars retain the eccentricity of the disk and, for a sufficiently massive initial cloud, produce an extremely top-heavy distribution of stellar masses. This potentially repetitive process may explain the presence of multiple eccentric rings of young stars in the presence of a supermassive black hole.
Impact of Clinical Variables on
Borrelia burgdorferi
-Specific Antibody Seropositivity in Acute-Phase Sera from Patients in North America with Culture-Confirmed Early Lyme Disease
Authors: Wormser Gary P. , Nowakowski John , Nadelman Robert B. , Visintainer Paul , Levin Andrew , Aguero-Rosenfeld Maria E.
Published: August 2008

Erythema migrans, the most common manifestation of Lyme disease, has been associated with highly variable rates of seropositivity for antibodies to
Borrelia burgdorferi
. Differences in the sensitivities of serologic assays for the detection of these antibodies, however, may not be the only or even the primary explanation for this observation. We investigated the impacts of four clinical variables on seropositivity—the duration of erythema migrans, the presence of single versus multiple skin lesions, and the gender and age of the patient. In this analysis, three different serologic tests were performed on acute-phase sera from 175 untreated patients with culture-confirmed erythema migrans: the C6 single-peptide enzyme-linked immunosorbent assay (ELISA), a commercially available ELISA in which a whole-cell sonicate of
B. burgdorferi
was the antigen, and a two-tier procedure. Irrespective of the serologic test performed, the results showed that seropositivity rates increased with the duration of the erythema migrans for patients with single lesions (
P
< 0.001) but not for those with multiple skin lesions. The variability in seropositivity rates was greatest for the two-tier testing strategy, with a >6-fold-higher rate of seropositivity among patients with a single lesion of 22- to 30-day duration than among those whose skin lesion was of 1- to 7-day duration (85.7 versus 14.1%;
P
< 0.001). Rates of seropositivity by each of the testing methods were also significantly higher for patients with multiple skin lesions than for those with single lesions (
P
< 0.001). In contrast, seropositivity rates were not affected by either the gender or the age of the patient. Thus, in patients with erythema migrans, certain clinical variables such as the duration and number of skin lesions had a profound impact on seropositivity rates, irrespective of the serologic assay performed.
Effects of Antibiotic Treatment on the Results of Nested PCRs for Scrub Typhus
Authors: Kim Dong-Min , Byun Joo Nam
Published: August 2008

In order to determine the effects of antibiotic treatment on the results of nested PCRs for scrub typhus, we investigated the frequency of positive outcomes at various times after antibiotic administration in patients with scrub typhus. The rate of detection by nested PCR with blood buffy coat before antibiotic administration was 90.5%. However, this decreased to 60.5% within 3 days after administration of antibiotics such as doxycycline and rifampin and to 10% by the fourth day following antibiotic administration. Since the sensitivity of nested PCR can be affected by antibiotic administration, clinicians should perform this PCR before antibiotic administration and at the latest within 3 days after antibiotic administration.
Acne is Not Associated with Yet-Uncultured Bacteria
Authors: Bek-Thomsen M. , Lomholt H. B. , Kilian M.
Published: August 2008

Current clinical and microbiological information on acne fails to demonstrate a clear association between particular species, including
Propionibacterium acnes
, and disease, and the disease continues to be a considerable problem. To test if acne is associated with hitherto uncultured bacteria residing in diseased skin follicles, sequencing and phylogenetic analysis of approximately 5,700 amplified and cloned 16S rRNA genes were used to determine the microbial diversity in follicles from acne patients and healthy individuals and from the superficial skin of acne patients. Follicles from healthy skin were exclusively colonized by
P. acnes
, whereas the follicular microbiota of acne patients included, in addition,
Staphylococcus epidermidis
and minor proportions of other species. In comparison, samples from superficial skin showed a complex microbiota represented by 12 to 16 bacterial species. The findings of the study exclude the possibility that acne is associated with yet-uncultured bacteria and shows that healthy skin follicles constitute a remarkably exclusive habitat allowing colonization only by
P. acnes
.
Evaluation of a Multiplex PCR Assay (Bruce-ladder) for Molecular Typing of All
Brucella
Species, Including the Vaccine Strains
Authors: López-Goñi I. , García-Yoldi D. , Marín C. M. , de Miguel M. J. , Muñoz P. M. , Blasco J. M. , Jacques I. , Grayon M. , Cloeckaert A. , Ferreira A. C. , Cardoso R. , Corrêa de Sá M. I. , Walravens K. , Albert D. , Garin-Bastuji B.
Published: August 2008

An evaluation of a multiplex PCR assay (Bruce-ladder) was performed in seven laboratories using 625
Brucella
strains from different animal and geographical origins. This robust test can differentiate in a single step all of the classical
Brucella
species, including those found in marine mammals and the S19, RB51, and Rev.1 vaccine strains.
Deployable Laboratory Response to Emergence of Melioidosis in Central Sri Lanka
Authors: Inglis Timothy J. J. , Merritt Adam , Montgomery Joanne , Jayasinghe Indika , Thevanesam Vasanthi , McInnes Russell
Published: August 2008

A portable molecular diagnostic laboratory was used to provide molecular confirmation of suspected melioidosis cases seen at Peradeniya Hospital, central Sri Lanka. Soil supernatants from rice field and rubber plantation samples also produced PCR-positive results. These procedures could be used for melioidosis field work in other remote locations.
Resistance Mutations in Human Immunodeficiency Virus Type 1 Integrase Selected with Elvitegravir Confer Reduced Susceptibility to a Wide Range of Integrase Inhibitors
Authors: Goethals Olivia , Clayton Reginald , Van Ginderen Marcia , Vereycken Inge , Wagemans Elisabeth , Geluykens Peggy , Dockx Koen , Strijbos Rudy , Smits Veerle , Vos Ann , Meersseman Geert , Jochmans Dirk , Vermeire Kurt , Schols Dominique , Hallenberger Sabine , Hertogs Kurt
Published: August 2008

Integration of viral DNA into the host chromosome is an essential step in the life cycle of retroviruses and is facilitated by the viral integrase enzyme. The first generation of integrase inhibitors recently approved or currently in late-stage clinical trials shows great promise for the treatment of human immunodeficiency virus (HIV) infection, but virus is expected to develop resistance to these drugs. Therefore, we used a novel resistance selection protocol to follow the emergence of resistant HIV in the presence of the integrase inhibitor elvitegravir (GS-9137). We find the primary resistance-conferring mutations to be Q148R, E92Q, and T66I and demonstrate that they confer a reduction in susceptibility not only to elvitegravir but also to raltegravir (MK-0518) and other integrase inhibitors. The locations of the mutations are highlighted in the catalytic sites of integrase, and we correlate the mutations with expected drug-protein contacts. In addition, mutations that do not confer reduced susceptibility when present alone (H114Y, L74M, R20K, A128T, E138K, and S230R) are also discussed in relation to their position in the catalytic core domain and their proximity to known structural features of integrase. These data broaden the understanding of antiviral resistance against integrase inhibitors and may give insight facilitating the discovery of second-generation compounds.
AKT1-Dependent Activation of NF-κB by the L Protein of Parainfluenza Virus 5
Authors: Luthra Priya , Sun Dengyun , Wolfgang Matthew , He Biao
Published: August 2008

Innate immunity plays a critical role in the control of viral infections. The induction of innate immune responses requires activation of transcription factors. In particular, NF-κB plays an essential role in activating the expression of cytokines involved in innate immunity such as beta interferon (IFN-β) and interleukin-6 (IL-6). However, the mechanisms by which viruses activate NF-κB are poorly defined. Infection by parainfluenza virus 5 (PIV5), a prototypical member of theParamyxoviridaefamily ofMononegavirales, has been shown to activate the expression of IFN-β and IL-6. To examine how PIV5 induces this expression, we have examined the activation of NF-κB by PIV5 proteins. We have found that expression of PIV5 L protein alone is sufficient to activate NF-κB. The L protein of PIV5, the catalytic component of the viral RNA-dependent RNA polymerase, contains six domains that are conserved among all negative-stranded nonsegmented RNA viruses. We have mapped the region that activates NF-κB to the second domain, which is thought to be involved in RNA synthesis. The activation of NF-κB by L requires AKT1, a serine/threonine kinase, since AKT1 small interfering RNA, an AKT inhibitor as well as a dominant-negative mutant of AKT1, blocks this activation. Furthermore, we have found that L interacts with AKT1 and enhances its phosphorylation. We speculate that L may encode AKT1 kinase activity.
E6 Proteins from Multiple Human Betapapillomavirus Types Degrade Bak and Protect Keratinocytes from Apoptosis after UVB Irradiation
Authors: Underbrink Michael P. , Howie Heather L. , Bedard Kristin M. , Koop Jennifer I. , Galloway Denise A.
Published: August 2008

Human papillomavirus (HPV) types from the beta genus (beta-HPVs) have been implicated in the development of skin cancer. A potentially important aspect of their carcinogenic role is the ability of the E6 protein to degrade the proapoptotic family member Bak, which gives cells the ability to survive UV damage. However, it is unknown if the ability to degrade Bak is limited to certain beta-HPV types or whether E6 expression in keratinocytes affects other proteins important for apoptosis signaling. We tested the abilities of E6 proteins from several representative members of the beta-HPVs to degrade Bak and protect UV-treated keratinocytes from apoptosis. The E6 proteins of the beta-HPV type 5 (HPV5), -8, -20, -22, -38, -76, -92, and -96, as well as the alpha genus HPV HPV16, all degraded Bak or prevented its accumulation following UV treatment but did not degrade Bak constitutively. In addition, when tested using HPV16 E6 (16E6) and 8E6 as representative E6 proteins from the alpha and beta genera, respectively, Bak degradation was dependent on the E3 ubiquitin ligase, E6AP. Other important regulators of apoptotic signaling were examined and found to be unperturbed by the expression of the beta-HPV E6 proteins. Importantly, the expression of beta-HPV E6 proteins protected keratinocytes from apoptosis to the same extent as 16E6-expressing cells. In conclusion, several of the beta-HPV types possess the ability to protect UV-treated keratinocytes from apoptosis by reducing levels of Bak in those cells, thus blocking the intrinsic apoptotic pathway.
Toll-Like Receptor 3 Has a Protective Role against West Nile Virus Infection
Authors: Daffis Stephane , Samuel Melanie A. , Suthar Mehul S. , Gale Michael , Diamond Michael S.
Published: August 2008

Protection against West Nile virus (WNV) infection requires rapid viral sensing and the generation of an interferon (IFN) response. Mice lacking IFN regulatory factor 3 (IRF-3) show increased vulnerability to WNV infection with enhanced viral replication and blunted IFN-stimulated gene (ISG) responses. IRF-3 functions downstream of several viral sensors, including Toll-like receptor 3 (TLR3), RIG-I, and MDA5. Cell culture studies suggest that host recognizes WNV in part, through the cytoplasmic helicase RIG-I and to a lesser extent, MDA5, both of which activate ISG expression through IRF-3. However, the role of TLR3 in vivo in recognizing viral RNA and activating antiviral defense pathways has remained controversial. We show here that an absence of TLR3 enhances WNV mortality in mice and increases viral burden in the brain. Compared to congenic wild-type controls, TLR3
−/−
mice showed relatively modest changes in peripheral viral loads. Consistent with this, little difference in multistep viral growth kinetics or IFN-α/β induction was observed between wild-type and TLR3
−/−
fibroblasts, macrophages, and dendritic cells. In contrast, a deficiency of TLR3 was associated with enhanced viral replication in primary cortical neuron cultures and greater WNV infection in central nervous system neurons after intracranial inoculation. Taken together, our data suggest that TLR3 serves a protective role against WNV in part, by restricting replication in neurons.
Identification of a Broad-Spectrum Arenavirus Entry Inhibitor
Authors: Larson Ryan A. , Dai Dongcheng , Hosack Virginia T. , Tan Ying , Bolken Tove’ C. , Hruby Dennis E. , Amberg Sean M.
Published: August 2008

Several arenaviruses, including Lassa virus (LASV), are causative agents of hemorrhagic fever, for which effective therapeutic options are lacking. The LASV envelope glycoprotein (GP) gene was used to generate lentiviral pseudotypes to identify small-molecule inhibitors of viral entry. A benzimidazole derivative with potent antiviral activity was identified from a high-throughput screen utilizing this strategy. Subsequent lead optimization for antiviral activity identified a modified structure, ST-193, with a 50% inhibitory concentration (IC
50
) of 1.6 nM against LASV pseudotypes. ST-193 inhibited pseudotypes generated with other arenavirus envelopes as well, including the remaining four commonly associated with hemorrhagic fever (IC
50
s for Junín, Machupo, Guanarito, and Sabiá were in the 0.2 to 12 nM range) but exhibited no antiviral activity against pseudotypes incorporating either the GP from the LASV-related arenavirus lymphocytic choriomeningitis virus (LCMV) or the unrelated G protein from vesicular stomatitis virus, at concentrations of up to 10 μM. Determinants of ST-193 sensitivity were mapped through a combination of LASV-LCMV domain-swapping experiments, genetic selection of viral variants, and site-directed mutagenesis. Taken together, these studies demonstrate that sensitivity to ST-193 is dictated by a segment of about 30 amino acids within the GP2 subunit. This region includes the carboxy-terminal region of the ectodomain and the predicted transmembrane domain of the envelope protein, revealing a novel antiviral target within the arenavirus envelope GP.
Epstein-Barr Virus Encodes Three Bona Fide Ubiquitin-Specific Proteases
Authors: Sompallae Ramakrishna , Gastaldello Stefano , Hildebrand Sebastian , Zinin Nikolay , Hassink Gerco , Lindsten Kristina , Haas Juergen , Persson Bengt , Masucci Maria G.
Published: August 2008

Manipulation of the ubiquitin proteasome system (UPS) is emerging as a common theme in viral pathogenesis. Some viruses have been shown to encode functional homologs of UPS enzymes, suggesting that a systematic identification of these products may provide new insights into virus-host cell interactions. Ubiquitin-specific proteases, collectively known as deubiquitinating enzymes (DUBs), regulate the activity of the UPS by hydrolyzing ubiquitin peptide or isopeptide bonds. The prediction of viral DUBs based on sequence similarity with known enzymes is hampered by the diversity of viral genomes. In this study sequence alignments, pattern searches, and hidden Markov models were developed for the conserved C- and H-boxes of the known DUB families and used to search the open reading frames (ORFs) of Epstein-Barr virus (EBV), a large gammaherpesvirus that has been implicated in the pathogenesis of a broad spectrum of human malignancies of lymphoid and epithelial cell origin. The searches identified a limited number of EBV ORFs that contain putative DUB catalytic domains. DUB activity was confirmed by functional assays and mutation analysis for three high scoring candidates, supporting the usefulness of this bioinformatics approach in predicting distant homologues of cellular enzymes.
Hepatitis C Virus-Specific T-Cell Gamma Interferon and Proliferative Responses Are More Common in Perihepatic Lymph Nodes than in Peripheral Blood or Liver
Authors: Moonka Dilip , Milkovich Kimberly A. , Rodriguez Benigno , Abouljoud Marwan , Lederman Michael M. , Anthony Donald D.
Published: August 2008

The activation state, differentiation state, and functions of liver lymphocytes and perihepatic lymph nodes during chronic hepatitis C virus (HCV) infection are not well understood. Here, we performed phenotypic and functional analyses of freshly prepared lymphocytes isolated from the livers, perihepatic lymph nodes, and peripheral blood compartments of chronic HCV-infected and disease control subjects with end-stage liver disease undergoing liver transplantation. We measured lymphocyte subset frequency and memory T-cell gamma interferon (IFN-γ) and proliferative responses to HCV peptide and control viral antigens in direct ex vivo assays. We found higher frequencies of CD4 cells in the lymph node compartment than in the other compartments for both HCV-infected and disease control subjects. Lymph node CD4 and CD8 cells less commonly expressed the terminal differentiation marker CD57, a finding consistent with an earlier differentiation state. In HCV-infected subjects, HCV-specific IFN-γ-producing and proliferative responses were commonly observed in the lymph node fraction, while they were uncommonly observed in the peripheral blood or liver fractions. In contrast, control viral CD4 protein antigen and CD8 peptide antigen-specific IFN-γ responses were commonly observed in the periphery and uncommonly observed in the lymph nodes of these same subjects. These findings are consistent with a selective defect in HCV-specific T-cell effector function or distribution in patients with advanced chronic HCV infection. The high frequency of HCV-reactive T cells in perihepatic lymph nodes indicates that a failure to generate or sustain T-lymphocyte HCV reactivity is not responsible for the paucity of functional cells even in end-stage liver disease.
Nef Can Enhance the Infectivity of Receptor-Pseudotyped Human Immunodeficiency Virus Type 1 Particles
Authors: Pizzato Massimo , Popova Elena , Göttlinger Heinrich G.
Published: August 2008

Nef is an accessory protein of human immunodeficiency virus type 1 (HIV-1) that enhances the infectivity of progeny virions when expressed in virus-producing cells. The requirement for Nef for optimal infectivity is, at least in part, determined by the envelope (Env) glycoprotein, because it can be eliminated by pseudotyping HIV-1 particles with pH-dependent Env proteins. To investigate the role of Env in the function of Nef, we have examined the effect of Nef on the infectivity of Env-deficient HIV-1 particles pseudotyped with viral receptors for cells expressing cognate Env proteins. We found that Nef significantly enhances the infectivity of CD4-chemokine receptor pseudotypes for cells expressing HIV-1 Env. Nef also increased the infectivity of HIV-1 particles pseudotyped with Tva, the receptor for subgroup A Rous sarcoma virus (RSV-A), even though Nef had no effect if the pH-dependent Env protein of RSV-A was used for pseudotyping. However, Nef does not always enhance viral infectivity if the normal orientation of the Env-receptor interaction is reversed, because the entry of Env-deficient HIV-1 into cells expressing the vesicular stomatitis virus G protein was unaffected by Nef. Together, our results demonstrate that the presence of a viral Env protein during virus production is not required for the ability of Nef to increase viral infectivity. Furthermore, since the infectivity of Tva pseudotypes was blocked by inhibitors of endosomal acidification, we conclude that low-pH-dependent entry does not always bypass the requirement for Nef.
Differential Modulation of prM Cleavage, Extracellular Particle Distribution, and Virus Infectivity by Conserved Residues at Nonfurin Consensus Positions of the Dengue Virus pr-M Junction
Authors: Junjhon Jiraphan , Lausumpao Matthawee , Supasa Sunpetchuda , Noisakran Sansanee , Songjaeng Adisak , Saraithong Prakaimuk , Chaichoun Kridsada , Utaipat Utaiwan , Keelapang Poonsook , Kanjanahaluethai Amornrat , Puttikhunt Chunya , Kasinrerk Watchara , Malasit Prida , Sittisombut Nopporn
Published: August 2008

In the generation of flavivirus particles, an internal cleavage of the envelope glycoprotein prM by furin is required for the acquisition of infectivity. Unlike cleavage of the prM of other flaviviruses, cleavage of dengue virus prM is incomplete in many cell lines; the partial cleavage reflects the influence of residues at furin nonconsensus positions of the pr-M junction, as flaviviruses share basic residues at positions P1, P2, and P4, recognized by furin. In this study, viruses harboring the alanine-scanning and other multiple-point mutations of the pr-M junction were generated, employing a dengue virus background that exhibited 60 to 70% prM cleavage and a preponderance of virion-sized extracellular particles. Analysis of prM and its cleavage products in viable mutants revealed a cleavage-suppressive effect at the conserved P3 Glu residue, as well as the cleavage-augmenting effects at the P5 Arg and P6 His residues, indicating an interplay between opposing modulatory influences mediated by these residues on the cleavage of the pr-M junction. Changes in the prM cleavage level were associated with altered proportions of extracellular virions and subviral particles; mutants with reduced cleavage were enriched with subviral particles and prM-containing virions, whereas the mutant with enhanced cleavage was deprived of these particles. Alterations of virus multiplication were detected in mutants with reduced prM cleavage and were correlated with their low specific infectivities. These findings define the functional roles of charged residues located adjacent to the furin consensus sequence in the cleavage of dengue virus prM and provide plausible mechanisms by which the reduction in the pr-M junction cleavability may affect virus replication.
Enhancement of Human Immunodeficiency Virus (HIV)-Specific CD8+T Cells in Cerebrospinal Fluid Compared to Those in Blood among Antiretroviral Therapy-Naïve HIV-Positive Subjects
Authors: Sadagopal Shanmugalakshmi , Lorey Shelly L. , Barnett Louise , Basham Rebecca , Lebo Laurie , Erdem Husamettin , Haman Kirsten , Avison Malcolm , Waddell Kevin , Haas David W. , Kalams Spyros A.
Published: August 2008

During untreated human immunodeficiency virus type 1 (HIV-1) infection, virus-specific CD8+T cells partially control HIV replication in peripheral lymphoid tissues, but host mechanisms of HIV control in the central nervous system (CNS) are incompletely understood. We characterized HIV-specific CD8+T cells in cerebrospinal fluid (CSF) and peripheral blood among seven HIV-positive antiretroviral therapy-naïve subjects. All had grossly normal brain magnetic resonance imaging and spectroscopy and normal neuropsychometric testing. Frequencies of epitope-specific CD8+T cells by direct tetramer staining were on average 2.4-fold higher in CSF than in blood (P= 0.0004), while HIV RNA concentrations were lower. Cells from CSF were readily expanded ex vivo and responded to a broader range of HIV-specific human leukocyte antigen class I restricted optimal peptides than did expanded cells from blood. HIV-specific CD8+T cells, in contrast to total CD8+T cells, in CSF and blood were at comparable maturation states, as assessed by CD45RO and CCR7 staining. The strong relationship between higher T-cell frequencies and lower levels of viral antigen in CSF could be the result of increased migration to and/or preferential expansion of HIV-specific T cells within the CNS. This suggests an important role for HIV-specific CD8+T cells in control of intrathecal viral replication.
Open Reading Frame 2, Encoded by the Latency-Related Gene of Bovine Herpesvirus 1, Has Antiapoptotic Activity in Transiently Transfected Neuroblastoma Cells
Authors: Shen Wenwen , Jones Clinton
Published: August 2008

The latency-related (LR) RNA encoded by bovine herpesvirus 1 is abundantly expressed in the trigeminal ganglia of latently infected calves. Expression of LR proteins is necessary for reactivation from latency and the protection of infected neurons from apoptosis. In this study, we demonstrated that an LR-encoded protein, open reading frame 2 (ORF-2), or ORF-2 fusion proteins encoded by alternatively spliced LR transcripts inhibit cold shock or Fas ligand-induced apoptosis in mouse neuroblastoma (neuro-2A) cells. Frameshift mutants of ORF-2 do not inhibit apoptosis, which suggests that protein expression, not LR RNA expression, mediates the antiapoptotic activity of the LR gene in transfected neuro-2A cells.
Genetically Divergent Strains of Feline Immunodeficiency Virus from the Domestic Cat (
Felis catus
) and the African Lion (
Panthera leo
) Share Usage of CD134 and CXCR4 as Entry Receptors
Authors: McEwan William A. , McMonagle Elizabeth L. , Logan Nicola , Serra Rodrigo C. , Kat Pieter , VandeWoude Sue , Hosie Margaret J. , Willett Brian J.
Published: August 2008

The
env
open reading frames of African lion (
Panthera leo
) lentivirus (feline immunodeficiency virus [FIV
Ple
]) subtypes B and E from geographically distinct regions of Africa suggest two distinct ancestries, with FIV
Ple
-E sharing a common ancestor with the domestic cat (
Felis catus
) lentivirus (FIV
Fca)
. Here we demonstrate that FIV
Ple
-E and FIV
Fca
share the use of CD134 (OX40) and CXCR4 as a primary receptor and coreceptor, respectively, and that both lion CD134 and CXCR4 are functional receptors for FIV
Ple
-E. The shared usage of CD134 and CXCR4 by FIV
Fca
and FIV
Ple
-E may have implications for in vivo cell tropism and the pathogenicity of the E subtype among free-ranging lion populations.
OBSERVATIONS ON AMYLOLYTIC BACTERIA: I. A SURVEY OF NAMED MESOPHILIC SPECIES ON SOLUBLE STARCH
Authors: Stark Egon , Tetrault P. A.
Published: August 2008

A survey was made of the ability of known, named, mesophilic strains of 40 bacterial species lo hydrolyze soluble starch in trypticase–yeast extract broth. The 40 species are either not described in Bergey's Manual as to their action on starch or they are listed as "not hvdrolyzing starch". Strains of 35 species hydrolyzed soluble starch, including seven spp. described as nonamyloytic. The latter were: Micrococcus pyogenes var. aureus, M. citreus, M. luteus, Escherichia coli, Erneinia carotovora, E. atroscptica, and Flazobacterium rhenanus. Strains of lour species failed to hydrolyze starch in repeated at tempts: Micrococcus sphaeroides, Goffkya tetragene, Neisseria catarrhalis, Serratia, rubida, Rhizobium trifolii failed to grow. The disappearance of the substrate is a more permanent characteristic than either the accumulation of acids or of reducing sugars. Additional tests are required when the starch iodine color is still blue after two weeks of incubation. The initial pH seems to influence amylase formation. Pertinent literature is quoted supporting the findings.
A HISTOLOGICAL STUDY OF SUGAR MAPLE DECAYED BY POLYPORUS GLOMERATUS PECK
Authors: Good H. M. , Nelson C. D.
Published: August 2008

Parenchyma cells of maple wood were found to remain alive, for many years after incorporation into the heartwood In wood invaded by Polyporus glomeratus Peck these cells had been killed in advance of the spreading mycelium, and their contents transformed into masses of dark brown wound gum. These, and similar masses which occasionally formed in the vessels and fibers, gave the outer part of the infected heartwood a characteristic dark color. The presence of wound gum appeared to inhibit development of decay, possibly by reason of the increase in pH with which it has been associated consistently. In tissues containing wound gum, decay was limited to slight delignification of certain cells in the intervessel areas, but following its disappearance disintegration of the tissues was rapid. Variation in resistance to decay was found to be related to variations in the reactions of cell walls to several staining procedures.
ACTIVITY OF ANTIBIOTICS AGAINST ASCOCHYTA PISI
Authors: Wallen V. R. , Skolko A. J.
Published: August 2008

A number of antibiotic substances which have been reported to possess antifungal properties were tested at various dilutions for their fungistatic activity upon spore germination of Ascochyta pisi. Actidione, antibiotic XG, and viridin (pH 3.5) were found to be fungistatic at dilutions of 10 p.p.m., gliotoxin and gladiolic acid at 20 p.p.m. The remaining antibiotics were less active, citronin showing no fungistatic activity even at 100 p.p.m. In fungicidal tests on spores of A. pisi, antibiotic XG, gliotoxin, actidione, humulon, gladiolic acid, and viridin were active at concentrations of 50 p.p.m. with a 12 hr. exposure, whereas clavacin, lupulon, and citronin required concentrations of 100 p.p.m. The action of these antibiotics upon germination of pea seed on filter paper and upon emergence in soil were tested and, in general, those which possessed the greatest fungistatic and fungicidal activity to A. pisi spores were the most phytotoxic. Only antibiotic XG and actidione gave adequate control of A. pisi when naturally infected pea seed was treated by soaking the seed in the antibiotic. Actidione, however, seriously reduced germination.
BIOCHEMISTRY OF THE USTILAGINALES: V. FACTORS AFFECTING THE FORMATION OF USTILAGIC ACID BY USTILAGO ZEAE
Authors: Thorn J. A. , Haskins R. H.
Published: August 2008

In a study of factors affecting the formation of ustilagic acid by Ustilago zeae (PRL 119) in submerged culture, yields of the acid ranging from 5 to 23 mgm. per ml. were obtained in three to five days, depending upon the concentration of medium constituents and the rate of aeration. The media employed contained cerelose, urea, corn steep liquor, and inorganic salts. Yields of ustilagic acid were usually between 8 and 15 mgm. per ml., corresponding to 12 to 23% conversion of the available glucose, on a carbon basis. Yields of the acid increased with increasing rates of aeration. Urea gave slightly higher yields than did the ammonium salts tested. Corn steep liquor concentration was optimal at 0.06%. Yields of ustilagic acid increased with increasing cerelose concentration, but the rate of conversion of carbohydrate into the acid decreased. About the same yields of ustilagic acid were obtained in shaken 500-ml. flasks, in nine-liter, and 30-liter fermentors.
ANTAGONISME DES MICROORGANISMES DU SOL ENVERS LE COLLETOTRICHUM LINICOLA AGENT DE L'ANTHRACNOSE DU LIN
Authors: Lachance Par René-O.
Published: August 2008

not available
STUDIES ON THE PERFECT STAGE OF HELMINTHOSPORIUM SATIVUM
Authors: Tinline R. D.
Published: August 2008

Cochlioboly sativus, the perfect stage of Helminthosporium sativum, developed in some paired cultures of monoconidial isolates. A satisfactory medium for the propagation of perithecia consists of kernels of barley placed on Sach's nutrient agar. The barley was prepared by surface sterilization, followed by boiling to kill the embryos. Cultural studies of monoascosporic isolates showed that the fungus is heterothallic in the sense that the isolates are hermaphroditic, self-sterile, intragroup sterile, and intergroup fertile. The change from a conidial to a mycelial-type colony in one isolate was shown to be a true mutation. The two compatibility groups in C. sativus were shown to be randomly distributed in nature. Isolates of the fungus from any one area were observed to fall into either compatibility group. A comparison of the author's C. sativus with the description of Ophiobolus sativus given by Ito and Kuribayashi led to the conclusion that these fungi are identical.
THE EFFECT OF BORON ON THE GROWTH AND SEED PRODUCTION OF ALSIKE CLOVER TRIFOLIUM HYBRIDUM L.
Authors: Montgomery F. H.
Published: August 2008

Alsike clover plants were grown in six different concentrations of boron to study the growth effect of boron on alsike clover and to observe how the intercrossing of plants having different boron conteat affected seed production. Boron deficiency symptoms occurred in plants grown in nutrient lacking boron, optimum vegetative growth took place in nutrient containing 0.1 to 0.25 p.p.m. boron, and toxicity was observed in plants grown in concentrations of 2.5 and 5.0 p.p.m. boron. Boron was required for flower and seed production, and the optimum level for seed production was 0.5 to 1.0 p.p.m. boron which was higher than that necessary for best vegetative growth. Good numbers of seeds were also obtained when pollen from plants grown in 1.0, 2.5, and 5.0 p.p.m. boron was used on pistils of plants grown in 0.1, 0.25, and 0.5 p.p.m. boron.
PRODUCTION AND PROPERTIES OF A POLYPHENOL OXIDASE FROM THE FUNGUS POLYPORUS VERSICOLORS
Authors: Dion W. M.
Published: August 2008

The fungus Polyporus versicolor was shown to produce an extracellular polyphenol oxidase system during growth in submerged culture. The enzyme was stable and active in acid solution, and ozidized lignin, vanillin, ferulic acid, and other phenolic substances. Vanillin and ferulic acid were converted to new compounds as a result of enzyme action, whereas lignin absorbed oxygen and appeared to become more water soluble.
PHYSIOLOGICAL AND BIOCHEMICAL STUDIES IN PLANT METABOLISM: V. THE EFFECT OF CHANGES IN SOIL WATER CONTENT ON THE PHYSIOLOGICAL HETEROGENEITY IN THE FIRST LEAF OF WHEAT
Authors: Roberts D. W. A.
Published: August 2008

The respiratory rate, soluble nitrogen content, protein nitrogen content, water content, reducing sugar content, and sucrose content of each of the four quarters of the first leaf of Khapli Emmer wheat have been determined for plants grown with different soil water supplies. Under dry conditions the first leaf of wheat contains a higher concentration of nitrogenous substances than it does under moist conditions. The water content of the first leaf of wheat grown in dry soil or very wet soil is lower than it is for leaves grown in moderately moist soil. The significance of these two observations is discussed. Further support has been obtained for the view that the concentration of none of the substances determined is solely responsible for the respiratory rates and gradients observed in the leaves. The role of leaf anatomy in controlling and producing the observed respiratory gradients is discussed.
GRASSLAND OF THE PEACE RIVER REGION, WESTERN CANADA
Authors: Moss E. H.
Published: August 2008

Natural grassland is associated with poplar and willow groves to form parkland areas on dark soils in the generally forested Peace River region of western Canada. The grassland is described as an Agropyron–Stipa–Carex community. Comprising this community are three subtypes or faciations, viz. Agropyron–Carex on low areas, Stipa on dry slopes, and Agropyron–Stipa on mesic sites. For the entire community 154 vascular species are recorded and for the Agropyron–Stipa faciation, which is the most common native grassland of the region, 139 vascular species, consisting of 36 graminoids, 84 forbs, and 19 woody species. The leading grasses are Agropyron trachycaulum, Stipa spartea var. curtiseta, and Koeleria cristata. The Agropyron–Stipa faciation is the "climax" grassland of the region and therefore may be classified as an "association". The occurrence of native grassland areas in the boreal forest region is explained in terms of special physiographic and edaphic features of these areas, notably poorly drained and inadequately aerated soils. Therefore, the Agropyron–Stipa grassland may be interpreted as an edaphic climax. Compared with the fescue grassland of south-central Alberta, the Peace River grassland lacks Festuca scabrella but has many of the other plants of the fescue association, certain of these assuming the role of leading species. Reliable indicators of early stages in grassland retrogression brought about by heavy grazing are the small sedges, Carex obtusata and C. heliophila.
THE INFLUENCE OF POLYPLOIDY ON THE X-RAY SENSITIVITY OF CELLS
Authors: Bishop Charles J.
Published: August 2008

A study has been made of the comparative X-ray sensitivity of cells of diploid and tetraploid species of Tradescantia at two different resting stages during the development of the pollen grains. At the resting stage midway between meiosis and the pollen grain division, no significant difference was found in the number of breaks per chromosome in the two species. At the resting stage just following the pollen grain division, the tetraploid chromosomes showed a slightly higher break frequency, a difference which was statistically significant. This increase was due, at least in part, to the presence of a small portion of cells which showed an abnormally high sensitivity. From a detailed study of the cells at each stage and the types of aberrations induced it is concluded that the chromosomes of each species are of equal sensitivity, and that any difference in the reaction of the diploid and tetraploid cells to irradiation is due simply to the numerical difference in the chromosomes of the cells, or to differences in the nuclear stage when X-rayed.
LONGEVITY OF SOME COMMON FUNGI IN CEREAL SEED
Authors: Machacek J. E. , Wallace H. A. H.
Published: August 2008

Tests made at regular intervals over a period of 10 years on naturally infested seed of wheat, oats, and barley that had been held in storage showed that most of the seed, while retaining its germinability, became free from viable fungi before the end of the storage period. Alternaria tenuis sensu Wiltshire in all three crops, Helminthosporium sativum P.K. & B. in wheat and barley, and Septoria nodorum Berk, in wheat died out comparatively rapidly. H. avenae Eidam in oats and H. teres Sacc. in barley lost their viability slowly and since, by the end of the storage period, most of the microorganisms associated with them in infested kernels were dead, these two fungi could generally be recovered in pure culture.
THE MICROSCOPIC WOOD STRUCTURE OF NORTH AMERICAN SPECIES OF CHAMAECYPARIS
Authors: Bannan M. W.
Published: August 2008

Trends in variation in different parts of the tree with regard to such anatomical features as tracheid and ray cell dimensions, size and distribution of rays, size and arrangement of pits, and thickness of cell walls resemble those recorded for other Cupressaceae. Comparative data relating to homologous wood samples show slight differences in mean values between the three American species of Chamaecyparis, but the intraspecific variability is usually so extensive that the specific ranges overlap widely. No single microscopic character seems completely reliable for diagnostic purposes, but certain structural features are valuable when used together. These are the frequency of ray tracheids in newly formed rays, the thickness of the horizontal and end walls of ray parenchyma cells, the number of pits per crossing field, and the height/width ratio of ray cells viewed tangentially.