bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring plasticity in the wild: laying date–temperature reaction norms in the common gull
Larus canus
Authors: Brommer Jon E , Rattiste Kalev , Wilson Alastair J
Published: January 2008

Exploration of causal components of plasticity is important for insight into evolutionary dynamics and an organism's ability to respond to climate change. Among individuals, variation in plasticity can be due to genotype–environment interaction (G×E) or a result from environmental effects associated with an individual. We investigated plasticity for laying date in the common gulls
Larus canus
, using data collected in Estonia during 37 years (
n
=11 624 records on 2262 females, with 472 relatives). We used a sliding window approach to find the period in spring during which mean temperature best explained the annual mean laying date. Then, considering the spring temperature as a quantitative description of the environment, we used pedigree information and a random regression animal model to determine the variation in plasticity for the laying date–temperature relationship. We found that individuals differ in the plasticity of laying date (such that there is increased variation among individuals for the laying date in warmer springs), and that approximately 11% of variation in the laying date is heritable, but we found no statistical support for G×E. Plasticity in this species is not constrained by warmer springs.
Estimating evolutionary parameters when viability selection is operating
Authors: Hadfield Jarrod D
Published: January 2008

Some individuals die before a trait is measured or expressed (the invisible fraction), and some relevant traits are not measured in any individual (missing traits). This paper discusses how these concepts can be cast in terms of missing data problems from statistics. Using missing data theory, I show formally the conditions under which a valid evolutionary inference is possible when the invisible fraction and/or missing traits are ignored. These conditions are restrictive and unlikely to be met in even the most comprehensive long-term studies. When these conditions are not met, many selection and quantitative genetic parameters cannot be estimated accurately unless the missing data process is explicitly modelled. Surprisingly, this does not seem to have been attempted in evolutionary biology. In the case of the invisible fraction, viability selection and the missing data process are often intimately linked. In such cases, models used in survival analysis can be extended to provide a flexible and justified model of the missing data mechanism. Although missing traits pose a more difficult problem, important biological parameters can still be estimated without bias when appropriate techniques are used. This is in contrast to current methods which have large biases and poor precision. Generally, the quantitative genetic approach is shown to be superior to phenotypic studies of selection when invisible fractions or missing traits exist because part of the missing information can be recovered from relatives.
Influence of Ply Sequence and Thermoelastic Stress Field on Asymmetric Delamination Growth Behavior Emanating From Elliptical Holes in Laminated FRP Composites
Authors: Pradhan Brajabandhu , Babu Poosa Ramesh
Published: January 2008

The present study encompasses the influence of ply sequence and thermoelastic stress field on asymmetric delamination growth behavior emanating from elliptical holes in laminated fiber reinforced polymeric composites. Results, emphasizing the effect of thermal residual stresses on delamination growth behavior of the composite laminates subjected to two different loading conditions, i.e., in-plane tensile and compressive loadings, are presented. Two sets of full three-dimensional finite element analyses have been performed to calculate the displacements and interlaminar stresses along the delaminated interfaces responsible for the delamination onset and propagation. Modified crack closure integral methods based on the concepts of linear elastic fracture mechanics have been followed to evaluate the individual modes of strain energy release rates along the delamination front. In each case, the delamination is embedded at a different depth along the thickness direction of the laminates. It is observed that the fiber orientation of the plies bounding the delamination front significantly influences the distribution of the local strain energy release rate. Also, the residual thermal stresses have a detrimental effect on the laminates subjected to compressive loading and more so in the case of laminates with delaminations existing closer to the top and bottom surfaces of the laminate.
Elasticity of (Mg,Fe)O Through the Spin Transition of Iron in the Lower Mantle
Authors: Crowhurst J. C. , Brown J. M. , Goncharov A. F. , Jacobsen S. D.
Published: January 2008

Changes in the electronic configuration of iron at high pressures toward a spin-paired state within host minerals ferropericlase and silicate perovskite may directly influence the seismic velocity structure of Earth's lower mantle. We measured the complete elastic tensor of ferropericlase, (Mg

1–
x

,Fe

x

)O (
x
= 0.06), through the spin transition of iron, whereupon the elastic moduli exhibited up to 25% softening over an extended pressure range from 40 to 60 gigapascals. These results are fully consistent with a simple thermodynamic description of the transition. Examination of previous compression data shows that the magnitude of softening increases with iron content up to at least
x
= 0.20. Although the spin transition in (Mg,Fe)O is too broad to produce an abrupt seismic discontinuity in the lower mantle, the transition will produce a correlated negative anomaly for both compressional and shear velocities that extends throughout most, if not all, of the lower mantle.
Concurrent Fast and Slow Cycling of a Transcriptional Activator at an Endogenous Promoter
Authors: Karpova Tatiana S. , Kim Min J. , Spriet Corentin , Nalley Kip , Stasevich Timothy J. , Kherrouche Zoulika , Heliot Laurent , McNally James G.
Published: January 2008

For gene regulation, some transcriptional activators bind periodically to promoters with either a fast (∼1 minute) or a slow (∼15 to 90 minutes) cycle. It is uncertain whether the fast cycle occurs on natural promoters, and the function of either cycle in transcription remains unclear. We report that fast and slow cycling can occur simultaneously on an endogenous yeast promoter and that slow cycling in this system reflects an oscillation in the fraction of accessible promoters rather than the recruitment and release of stably bound transcriptional activators. This observation, combined with single-cell measurements of messenger RNA (mRNA) production, argues that fast cycling initiates transcription and that slow cycling regulates the quantity of mRNA produced. These findings counter the prevailing view that slow cycling initiates transcription.
NFAT Binding and Regulation of T Cell Activation by the Cytoplasmic Scaffolding Homer Proteins
Authors: Huang Guo N. , Huso David L. , Bouyain Samuel , Tu Jianchen , McCorkell Kelly A. , May Michael J. , Zhu Yuwen , Lutz Michael , Collins Samuel , Dehoff Marlin , Kang Shin , Whartenby Katharine , Powell Jonathan , Leahy Daniel , Worley Paul F.
Published: January 2008

T cell receptor (TCR) and costimulatory receptor (CD28) signals cooperate in activating T cells, although understanding of how these pathways are themselves regulated is incomplete. We found that Homer2 and Homer3, members of the Homer family of cytoplasmic scaffolding proteins, are negative regulators of T cell activation. This is achieved through binding of nuclear factor of activated T cells (NFAT) and by competing with calcineurin. Homer-NFAT binding was also antagonized by active serine-threonine kinase AKT, thereby enhancing TCR signaling via calcineurin-dependent dephosphorylation of NFAT. This corresponded with changes in cytokine expression and an increase in effector-memory T cell populations in Homer-deficient mice, which also developed autoimmune-like pathology. These results demonstrate a further means by which costimulatory signals are regulated to control self-reactivity.
Irreconcilable Differences: Fine-Root Life Spans and Soil Carbon Persistence
Authors: Strand Allan E. , Pritchard Seth G. , McCormack M. Luke , Davis Micheal A. , Oren Ram
Published: January 2008

The residence time of fine-root carbon in soil is one of the least understood aspects of the global carbon cycle, and fine-root dynamics are one of the least understood aspects of plant function. Most recent studies of these belowground dynamics have used one of two methodological strategies. In one approach, based on analysis of carbon isotopes, the persistence of carbon is inferred; in the other, based on direct observations of roots with cameras, the longevity of individual roots is measured. We show that the contribution of fine roots to the global carbon cycle has been overstated because observations of root lifetimes systematically overestimate the turnover of fine-root biomass. On the other hand, isotopic techniques systematically underestimate the turnover of individual roots. These differences, by virtue of the separate processes or pools measured, are irreconcilable.
Evaluation of Feline Monocyte-Derived Dendritic Cells Loaded with Internally Inactivated Virus as a Vaccine against Feline Immunodeficiency Virus
Authors: Freer Giulia , Matteucci Donatella , Mazzetti Paola , Tarabella Francesca , Catalucci Valentina , Ricci Enrica , Merico Antonio , Bozzacco Leonia , Pistello Mauro , Bendinelli Mauro
Published: January 2008

Dendritic cells are the only antigen-presenting cells that can present exogenous antigens to both helper and cytolytic T cells and prime Th1-type or Th2-type cellular immune responses. Given their unique immune functions, dendritic cells are considered attractive “live adjuvants” for vaccination and immunotherapy against cancer and infectious diseases. The present study was carried out to assess whether the reinjection of autologous monocyte-derived dendritic cells loaded with an aldithriol-2-inactivated primary isolate of feline immune deficiency virus (FIV) was able to elicit protective immune responses against the homologous virus in naive cats. Vaccine efficacy was assessed by monitoring immune responses and, finally, by challenge with the homologous virus of vaccinated, mock-vaccinated, and healthy cats. The outcome of challenge was followed by measuring cellular and antibody responses and viral and proviral loads and quantitating FIV by isolation and a count of CD4
+
/CD8
+
T cells in blood. Vaccinated animals exhibited clearly evident FIV-specific peripheral blood mononuclear cell proliferation and antibody titers in response to immunization; however, they became infected with the challenge virus at rates comparable to those of control animals.
Characterization of Genetic Diversity of Carbapenem-ResistantAcinetobacter baumanniiClinical Strains Collected from 2004 to 2007
Authors: Qi Chao , Malczynski Michael , Parker Michelle , Scheetz Marc H.
Published: January 2008

Genotypes of carbapenem-resistantAcinetobacter baumanniicollected by the clinical microbiology laboratory of a university hospital in Chicago, IL, between 2004 and 2007 were analyzed by pulsed-field gel electrophoresis. A single genotype established predominance after being introduced in 2005. Analysis of carbapenemases by PCR revealed that imipenem resistance but not meropenem resistance was associated with the presence ofblaOXA-23andblaOXA-40genes.
Transmission Events within Outbreaks of Gastroenteritis Determined through Analysis of Nucleotide Sequences of the P2 Domain of Genogroup II Noroviruses
Authors: Xerry Jacqueline , Gallimore Chris I. , Iturriza-Gómara Miren , Allen David J. , Gray Jim J.
Published: January 2008

Tracking the spread of noroviruses during outbreaks of gastroenteritis is hampered by the lack of sequence diversity in those regions of the genome chosen for virus detection and characterization. Sequence analysis of regions of the genes encoding the RNA-dependent RNA polymerase and the S domain of the capsid does not provide sufficient discrimination between genotypically related strains of different outbreaks. However, analysis of sequences derived from the region encoding the P2 domain showed 100% similarity among strains from the same outbreak and <100% similarity among strains of different outbreaks. The prolonged nature of some hospital outbreaks, links between hospitals, and the introduction of multiple strains of a single genotype associated with an outbreak aboard a cruise ship were determined using this method. This provides a powerful tool for tracking outbreak strains and the subsequent analysis and validation of interventions in a background of multiple introductions of virus strains of the same genotype or genetic cluster.
IRF-1 Is Required for Full NF-κB Transcriptional Activity at the Human Immunodeficiency Virus Type 1 Long Terminal Repeat Enhancer
Authors: Sgarbanti Marco , Remoli Anna L. , Marsili Giulia , Ridolfi Barbara , Borsetti Alessandra , Perrotti Edvige , Orsatti Roberto , Ilari Ramona , Sernicola Leonardo , Stellacci Emilia , Ensoli Barbara , Battistini Angela
Published: January 2008

Human immunodeficiency virus type 1 (HIV-1) gene expression is controlled by a complex interplay between viral and host factors. We have previously shown that interferon-regulatory factor 1 (IRF-1) is stimulated early after HIV-1 infection and regulates promoter transcriptional activity even in the absence of the viral transactivator Tat. In this work we demonstrate that IRF-1 is also required for full NF-κB transcriptional activity. We provide evidence that IRF-1 and NF-κB form a functional complex at the long terminal repeat (LTR) κB sites, which is abolished by specific mutations in the two adjacent κB sites in the enhancer region. Silencing IRF-1 with small interfering RNA resulted in impaired NF-κB-mediated transcriptional activity and in repressed HIV-1 transcription early in de novo-infected T cells. These data indicate that in early phases of HIV-1 infection or during virus reactivation from latency, when the viral transactivator is absent or present at very low levels, IRF-1 is an additional component of the p50/p65 heterodimer binding the LTR enhancer, absolutely required for efficient HIV-1 replication.
Rearrangements of Rotavirus Genomic Segment 11 Are Generated during Acute Infection of Immunocompetent Children and Do Not Occur at Random
Authors: Schnepf Nathalie , Deback Claire , Dehee Axelle , Gault Elyanne , Parez Nathalie , Garbarg-Chenon Antoine
Published: January 2008

Group A rotaviruses are the main cause of viral gastroenteritis in infants. The viral genome consists of 11 double-stranded RNA (dsRNA) segments. Dysfunction of the viral RNA polymerase can lead to gene rearrangements, which most often consist of partial sequence duplication of a dsRNA segment. Gene rearrangements have been detected in vivo during chronic infection in immunodeficient children or in vitro during passages at a high multiplicity of infection in cell culture, suggesting that these replication conditions lead to selective advantages favoring the recovery of viruses with rearranged genes. During acute rotavirus infection, the replication level is high, but the occurrence of rearrangement events has never been reported. By the use of a reverse transcription-PCR assay specifically designed to detect small numbers of copies of rearranged forms of segment 11 in a high background of its standard counterpart, we detected 12 rearrangement events among 161 cases (7.5%) of acute rotavirus infection in immunocompetent children. Strikingly, in all but one case, rearrangement took place at the same location within the short direct repeat AUGU sequence. For the unique case with a different rearrangement pattern, the rearrangement occurred within the direct repeat ACAAGUC that was specific for this isolate. In conclusion, we report the occurrence of segment 11 rearrangements during acute rotavirus infection in immunocompetent children. We show that under such conditions of infection, the viral RNA polymerase generates rearrangements which occur not at random but within direct repeats which might constitute hot spots for RNA recombination.
Antiviral RNA Silencing Is Restricted to the Marginal Region of the Dark Green Tissue in the Mosaic Leaves of
Tomato Mosaic Virus
-Infected Tobacco Plants
Authors: Hirai Katsuyuki , Kubota Kenji , Mochizuki Tomofumi , Tsuda Shinya , Meshi Tetsuo
Published: January 2008

Mosaic is a common disease symptom caused by virus infection in plants. Mosaic leaves of
Tomato mosaic virus
(ToMV)-infected tobacco plants consist of yellow-green and dark green tissues that contain large and small numbers of virions, respectively. Although the involvement of RNA silencing in mosaic development has been suggested, its role in the process that results in an uneven distribution of the virus is unknown. Here, we investigated whether and where ToMV-directed RNA silencing was established in tobacco mosaic leaves. When transgenic tobaccos defective in RNA silencing were infected with ToMV, little or no dark green tissue appeared, implying the involvement of RNA silencing in mosaic development. ToMV-related small interfering RNAs were rarely detected in the dark green areas of the first mosaic leaves, and their interior portions were susceptible to infection. Thus, ToMV-directed RNA silencing was not effective there. By visualizing the cells where ToMV-directed RNA silencing was active, it was found that the effective silencing occurs only in the marginal regions of the dark green tissue (∼0.5 mm in width) and along the major veins. Further, the cells in the margins were resistant against recombinant potato virus X carrying a ToMV-derived sequence. These findings demonstrate that RNA silencing against ToMV is established in the cells located at the margins of the dark green areas, restricting the expansion of yellow-green areas, and consequently defines the mosaic pattern. The mechanism of mosaic symptom development is discussed in relation to the systemic spread of the virus and RNA silencing.
Immunomodulatory Properties of a Viral Homolog of Human Interleukin-10 Expressed by Human Cytomegalovirus during the Latent Phase of Infection
Authors: Jenkins C. , Garcia W. , Godwin M. J. , Spencer J. V. , Stern J. Lewis , Abendroth A. , Slobedman B.
Published: January 2008

Human cytomegalovirus (HCMV) establishes a latent infection in hematopoietic cells, from which it can reactivate to cause significant disease in immunocompromised individuals. HCMV expresses a functional homolog of the immunosuppressive cytokine interleukin-10 (termed cmvIL-10), and alternate splicing of the cmvIL-10 transcript results in expression of a latency-associated cmvIL-10 transcript (LAcmvIL-10). To determine whether LAcmvIL-10 encodes immunosuppressive functions, recombinant LAcmvIL-10 protein was generated, and its impact on major histocompatibility complex class II (MHC-II) expression was examined on granulocyte macrophage progenitor cells (GM-Ps) and monocytes. LAcmvIL-10 (and cmvIL-10) downregulated MHC-II on the surfaces of both cell types. This downregulation was associated with a decrease in total MHC-II protein and transcription of components of the MHC-II biosynthesis pathway. Unlike cmvIL-10, LAcmvIL-10 did not trigger phosphorylation of Stat3, and its ability to downregulate MHC-II was not blocked by neutralizing antibodies to the human IL-10 receptor, suggesting that LAcmvIL-10 either does not engage the cellular IL-10 receptor or utilizes it in a different manner from cmvIL-10. The impact of LAcmvIL-10 on dendritic cell (DC) maturation was also assessed. In contrast to cmvIL-10, LAcmvIL-10 did not inhibit the expression of costimulatory molecules CD40, CD80, and CD86 and the maturation marker CD83 on DCs, nor did it inhibit proinflammatory cytokines (IL-1α, IL-1β, IL-6 and tumor necrosis factor alpha). Thus, LAcmvIL-10 retains some, but not all, of the immunosuppressive functions of cmvIL-10. As GM-Ps and monocytes support latent infection, expression of LAcmvIL-10 may enable HCMV to avoid immune recognition and clearance during latency.
Kaposi's Sarcoma-Associated Herpesvirus Transactivator RTA Promotes Degradation of the Repressors To Regulate Viral Lytic Replication
Authors: Yang Zhilong , Yan Zhangcai , Wood Charles
Published: January 2008

Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8 (KSHV/HHV-8) RTA is an important protein involved in the induction of KSHV lytic replication from latency through activation of the lytic cascade. A number of cellular and viral proteins, including K-RBP, have been found to repress RTA-mediated transactivation and KSHV lytic replication. However, it is unclear as to how RTA overcomes the suppression during lytic reactivation. In this study, we found that RTA can induce K-RBP degradation through the ubiquitin-proteasome pathway and that two regions in RTA are responsible. Moreover, we found that RTA can promote the degradation of several other RTA repressors. RTA mutants that are defective in inducing K-RBP degradation cannot activate RTA responsive promoter as efficiently as wild-type RTA. Interference of the ubiquitin-proteasome pathway affected RTA-mediated transactivation and KSHV reactivation from latency. Our results suggest that KSHV RTA can stimulate the turnover of repressors to modulate viral reactivation. Since herpes simplex virus type 1 transactivator ICP0 and human cytomegalovirus transactivator pp71 also stimulate the degradation of cellular silencers, it is possible that the promotion of silencer degradation by viral transactivators may be a common mechanism for regulating the lytic replication of herpesviruses.
Full Genome-Based Classification of Rotaviruses Reveals a Common Origin between Human Wa-Like and Porcine Rotavirus Strains and Human DS-1-Like and Bovine Rotavirus Strains
Authors: Matthijnssens Jelle , Ciarlet Max , Heiman Erica , Arijs Ingrid , Delbeke Thomas , McDonald Sarah M. , Palombo Enzo A. , Iturriza-Gómara Miren , Maes Piet , Patton John T. , Rahman Mustafizur , Van Ranst Marc
Published: January 2008

Group A rotavirus classification is currently based on the molecular properties of the two outer layer proteins, VP7 and VP4, and the middle layer protein, VP6. As reassortment of all the 11 rotavirus gene segments plays a key role in generating rotavirus diversity in nature, a classification system that is based on all the rotavirus gene segments is desirable for determining which genes influence rotavirus host range restriction, replication, and virulence, as well as for studying rotavirus epidemiology and evolution. Toward establishing such a classification system, gene sequences encoding VP1 to VP3, VP6, and NSP1 to NSP5 were determined for human and animal rotavirus strains belonging to different G and P genotypes in addition to those available in databases, and they were used to define phylogenetic relationships among all rotavirus genes. Based on these phylogenetic analyses, appropriate identity cutoff values were determined for each gene. For the VP4 gene, a nucleotide identity cutoff value of 80% completely correlated with the 27 established P genotypes. For the VP7 gene, a nucleotide identity cutoff value of 80% largely coincided with the established G genotypes but identified four additional distinct genotypes comprised of murine or avian rotavirus strains. Phylogenetic analyses of the VP1 to VP3, VP6, and NSP1 to NSP5 genes showed the existence of 4, 5, 6, 11, 14, 5, 7, 11, and 6 genotypes, respectively, based on nucleotide identity cutoff values of 83%, 84%, 81%, 85%, 79%, 85%, 85%, 85%, and 91%, respectively. In accordance with these data, a revised nomenclature of rotavirus strains is proposed. The novel classification system allows the identification of (i) distinct genotypes, which probably followed separate evolutionary paths; (ii) interspecies transmissions and a plethora of reassortment events; and (iii) certain gene constellations that revealed (a) a common origin between human Wa-like rotavirus strains and porcine rotavirus strains and (b) a common origin between human DS-1-like rotavirus strains and bovine rotaviruses. These close evolutionary links between human and animal rotaviruses emphasize the need for close simultaneous monitoring of rotaviruses in animals and humans.
Three-Dimensional Structure of Canine Adenovirus Serotype 2 Capsid
Authors: Schoehn Guy , El Bakkouri Majida , Fabry Céline M. S. , Billet Oliver , Estrozi Leandro F. , Le Long , Curiel David T. , Kajava Andrey V. , Ruigrok Rob W. H. , Kremer Eric J.
Published: January 2008

There are more than 100 known adenovirus (AdV) serotypes, including 50 human serotypes. Because AdV-induced disease is relatively species specific, vectors derived from nonhuman serotypes may have wider clinical potential based, in part, on the lack of ubiquitous memory immunity. Whereas a few of the human serotype capsids have been studied at the structural level, none of the nonhuman serotypes has been analyzed. The basis laid by the analysis of human AdV (hAdV) has allowed us to determine and compare the three-dimensional structure of the capsid of canine serotype 2 (CAV-2) to that of hAdV serotype 5 (hAdV-5). We show that CAV-2 capsid has a smoother structure than the human serotypes. Many of the external loops found in the hAdV-5 penton base and the hexon, against which the antibody response is directed, are shorter or absent in CAV-2. On the other hand, the CAV-2 fiber appears to be more complex, with two bends in the shaft. An interesting difference between the human and canine viruses is that the C-terminal part of protein IX is in a different position, making an antenna sticking out of the CAV-2 capsid. The comparison between the two viruses allows the identification of sites that should be easy to modify on the CAV-2 capsid for altering tissue tropism or other biological activities.
Short-Lived Infected Cells Support Virus Replication in Sooty Mangabeys Naturally Infected with Simian Immunodeficiency Virus: Implications for AIDS Pathogenesis
Authors: Gordon Shari N. , Dunham Richard M. , Engram Jessica C. , Estes Jacob , Wang Zichun , Klatt Nichole R. , Paiardini Mirko , Pandrea Ivona V. , Apetrei Cristian , Sodora Donald L. , Lee Ha Youn , Haase Ashley T. , Miller Michael D. , Kaur Amitinder , Staprans Silvija I. , Perelson Alan S. , Feinberg Mark B. , Silvestri Guido
Published: January 2008

Sooty mangabeys (SMs) naturally infected with simian immunodeficiency virus (SIV) do not develop AIDS despite high levels of virus replication. At present, the mechanisms underlying this disease resistance are poorly understood. Here we tested the hypothesis that SIV-infected SMs avoid immunodeficiency as a result of virus replication occurring in infected cells that live significantly longer than human immunodeficiency virus (HIV)-infected human cells. To this end, we treated six SIV-infected SMs with potent antiretroviral therapy (ART) and longitudinally measured the decline in plasma viremia. We applied the same mathematical models used in HIV-infected individuals and observed that SMs naturally infected with SIV also present a two-phase decay of viremia following ART, with the bulk (92 to 99%) of virus replication sustained by short-lived cells (average life span, 1.06 days), and only 1 to 8% occurring in longer-lived cells. In addition, we observed that ART had a limited impact on CD4
+
T cells and the prevailing level of T-cell activation and proliferation in SIV-infected SMs. Collectively, these results suggest that in SIV-infected SMs, similar to HIV type 1-infected humans, short-lived activated CD4
+
T cells, rather than macrophages, are the main source of virus production. These findings indicate that a short in vivo life span of infected cells is a common feature of both pathogenic and nonpathogenic primate lentivirus infections and support a model for AIDS pathogenesis whereby the direct killing of infected cells by HIV is not the main determinant of disease progression.
Cdc55p-Mediated E4orf4 Growth Inhibition in
Saccharomyces cerevisiae
Is Mediated Only in Part via the Catalytic Subunit of Protein Phosphatase 2A
Authors: Li Yikun , Wei Huijun , Hsieh Tung-Chin , Pallas David C.
Published: January 2008

The adenovirus early region 4 open reading frame 4 (E4orf4) protein specifically induces p53-independent cell death of transformed but not normal human cells, suggesting that elucidation of its mechanism may provide important new avenues for cancer therapy. Wild-type E4orf4 and mutants that retain cancer cell toxicity also induce growth inhibition in
Saccharomyces cerevisiae
, which provides a genetically tractable system for studying E4orf4 function. Interaction with the protein phosphatase 2A (PP2A) B regulatory subunit is required for E4orf4's effects, suggesting that E4orf4 may function by regulating B subunit-containing heterotrimeric PP2A holoenzymes (PP2A
BAC
), which consist of a B subunit complexed with the PP2A structural (A) and catalytic (C) subunits. However, it is not known whether E4orf4-induced growth inhibition requires interaction with the PP2A C subunit or whether E4orf4 might have PP2A B subunit-dependent effects that are independent of PP2A
BAC
holoenzyme formation. To test these possibilities in
S. cerevisiae
, we disrupted the stable formation of PP2A
BAC
heterotrimers and thus E4orf4/C subunit association by PP2A C subunit point mutations or by deletion of the gene for the PP2A methyltransferase, Ppm1p, and assayed for effects on E4orf4-induced growth inhibition. Our results support a model in which E4orf4 mediates growth inhibition and cell killing both through PP2A
BAC
heterotrimers and through a B regulatory subunit-dependent pathway(s) that is independent of stable complex formation with the PP2A C subunit. They also indicate that Ppm1p has a function other than regulating the assembly of PP2A heterotrimers and suggest that selective PP2A trimer inhibitors and PP6 inhibitors may be useful as adjuvant anticancer therapies.
Identification of the Progenitors of Indonesian and Vietnamese Avian Influenza A (H5N1) Viruses from Southern China
Authors: Wang J. , Vijaykrishna D. , Duan L. , Bahl J. , Zhang J. X. , Webster R. G. , Peiris J. S. M. , Chen H. , Smith Gavin J. D. , Guan Y.
Published: January 2008

The transmission of highly pathogenic avian influenza H5N1 virus to Southeast Asian countries triggered the first major outbreak and transmission wave in late 2003, accelerating the pandemic threat to the world. Due to the lack of influenza surveillance prior to these outbreaks, the genetic diversity and the transmission pathways of H5N1 viruses from this period remain undefined. To determine the possible source of the wave 1 H5N1 viruses, we recently conducted further sequencing and analysis of samples collected in live-poultry markets from Guangdong, Hunan, and Yunnan in southern China from 2001 to 2004. Phylogenetic analysis of the hemagglutinin and neuraminidase genes of 73 H5N1 isolates from this period revealed a greater genetic diversity in southern China than previously reported. Moreover, results show that eight viruses isolated from Yunnan in 2002 and 2003 were most closely related to the clade 1 virus sublineage from Vietnam, Thailand, and Malaysia, while two viruses from Hunan in 2002 and 2003 were most closely related to viruses from Indonesia (clade 2.1). Further phylogenetic analyses of the six internal genes showed that all 10 of those viruses maintained similar phylogenetic relationships as the surface genes. The 10 progenitor viruses were genotype Z and shared high similarity (≥99%) with their corresponding descendant viruses in most gene segments. These results suggest a direct transmission link for H5N1 viruses between Yunnan and Vietnam and also between Hunan and Indonesia during 2002 and 2003. Poultry trade may be responsible for virus introduction to Vietnam, while the transmission route from Hunan to Indonesia remains unclear.
Scavenger Receptor Class B Is Required for Hepatitis C Virus Uptake and Cross-Presentation by Human Dendritic Cells
Authors: Barth Heidi , Schnober Eva K. , Neumann-Haefelin Christoph , Thumann Christine , Zeisel Mirjam B. , Diepolder Helmut M. , Hu Zongyi , Liang T. Jake , Blum Hubert E. , Thimme Robert , Lambotin Mélanie , Baumert Thomas F.
Published: January 2008

Class B scavenger receptors (SR-Bs) bind lipoproteins and play an important role in lipid metabolism. Most recently, SR-B type I (SR-BI) and its splicing variant SR-BII have been found to mediate bacterial adhesion and cytosolic bacterial invasion in mammalian cells. In this study, we demonstrate that SR-BI is a key host factor required for hepatitis C virus (HCV) uptake and cross-presentation by human dendritic cells (DCs). Whereas monocytes and T and B cells were characterized by very low or undetectable SR-BI expression levels, human DCs demonstrated a high level of cell surface expression of SR-BI similar to that of primary human hepatocytes. Antibodies targeting the extracellular loop of SR-BI efficiently inhibited HCV-like particle binding, uptake, and cross-presentation by human DCs. Moreover, human high-density lipoprotein specifically modulated HCV-like particle binding to DCs, indicating an interplay of HCV with the lipid transfer function of SR-BI in DCs. Finally, we demonstrate that anti-SR-BI antibodies inhibit the uptake of cell culture-derived HCV (HCVcc) in DCs. In conclusion, these findings identify a novel function of SR-BI for viral antigen uptake and recognition and may have an important impact on the design of HCV vaccines and immunotherapeutic approaches aiming at the induction of efficient antiviral immune responses.
Boron Units as Pharmacophores - New Applications and Opportunities of Boron Cluster Chemistry
Authors: Lesnikowski Zbigniew J.
Published: January 2008

Carboranes (dicarba-closo-dodecaboranes) are a class of carbon-containing polyhedral boron-cluster compounds showing remarkable hydrophobic character, chemical and thermal stability, and resistance to catabolism in biological environment. These features allow application of boron clusters as new hydrophobic core structure in biologically active molecules that interact hydrophobically with proteins, thus facilitating new drug design. A review with 45 references.
Electronic Nature of B-H-B Bridges and Their Manifestation in Vibrational Spectra of 11-Vertex nido-Carbaboranes
Authors: Leites Larissa A. , Kononova Elena G. , Bukalov Sergey S.
Published: January 2008

AIM analysis of electron density function based on the results of DFT B3LYP calculations was carried out for six 11-vertex nido-carbaboranes containing B-H-B bridges. The vibrational modes of B-H-B bridges were investigated experimentally and theoretically. The results obtained allowed some conclusions about the electronic structure of the species studied and the role of B-H-B bridges in the cage bonding pattern.
Synthesis of Functional Derivatives of 7,8-Dicarba-nido-undecaborate Anion by Ring-Opening of Its Cyclic Oxonium Derivatives
Authors: Stogniy Marina Yu. , Abramova Ekaterina N. , Lobanova Irina A. , Sivaev Igor B. , Bragin Vikentii I. , Petrovskii Pavel V. , Tsupreva Viktoria N. , Sorokina Olga V. , Bregadze Vladimir I.
Published: January 2008

A new approach to synthesis of functional derivatives of 7,8-dicarba-nido-undecaborate anion based on ring-opening of its cyclic oxonium derivatives [10-(CH2)4O-7,8-C2B9H11] and [10-O(CH2CH2)2O-7,8-C2B9H11] with various nucleophiles was developed. Both cyclic oxonium derivatives can be obtained as single isomers by reaction of the parent anion [7,8-C2B9H12]- with mercury(II) chloride in the corresponding solvents. Mechanism of formation of the cyclic oxonium derivatives of 7,8-dicarba-nido-undecaborate anion was proposed. A series of 7,8-dicarba-nido-undecaborate derivatives with terminal carboxylic and azide functions were prepared by the ring-opening reactions of the cyclic oxonium derivatives with substituted phenolate and azide ions, respectively.
Smoking in the home and children’s health
Authors: Hill S C , Liang L
Published: January 2008

Objectives:

We estimate for young children the annual excess health service use, healthcare expenditures, and disability bed days for respiratory conditions associated with exposure to smoking in the home in the United States.

Methods:

Health service use, healthcare expenditures and disability bed days data come from the 1999 and 2001 Medical Expenditure Panel Survey (MEPS). Reported smoking in the home comes from the linked National Health Interview Survey, from which the MEPS sample is drawn. Multivariate statistical analysis controls for potential confounding factors. The sample is 2759 children aged 0–4.

Results:

Smoking in the home is associated with an increase in the probability of emergency department visits for respiratory conditions by five percentage points and the probability of inpatient use for these conditions by three percentage points. There is no relation between indoor smoking by adults and either ambulatory visits or prescription drug expenditures. Overall, indoor smoking is associated with $117 in additional healthcare expenditures for respiratory conditions for each exposed child aged 0–4. Indoor smoking is also associated with an eight percentage point increase in the probability of having a bed day because of respiratory illness for children aged 1–4.

Conclusions:

Despite the significant progress made in tobacco control, many children are still exposed to secondhand smoke in their home. Reducing exposure to smoking in the home would probably reduce healthcare expenditures for respiratory conditions and improve children’s health.
Observations on the mechanism of flagellar retraction in Saprolegnia terrestris
Authors: Holloway Shirley A. , Heath I. Brent
Published: January 2008

Cinematographic analysis of encysting primary zoospores of Saprolegnia terrestris showed asynchronous flagellar retraction. The data are most compatible with a retraction model involving mainly asynchronous microtubule depolymerization with "wrap-around" of the final fragment of each flagellum.
High resolution measurement of plant growth
Authors: Penny David , Penny Pauline , Marshall D. C.
Published: January 2008

The use of displacement transducers coupled with suitable recording equipment is described for high resolution (0.1 µm) automatic measurements of plant growth. Systems are described for measurements on intact seedlings or isolated sections and for measuring mechanical properties of cell walls. The equipment can be used simultaneously for several channels and is suitable for on-line computer calculation and plotting of results. Examples of typical results are given for the different applications.
Some ultrastructural features in the Genus Septobasidium
Authors: Dykstra Michael J.
Published: January 2008

The ultrastructure of the hyphae characteristic of five species of Septobasidium was examined and general features were noted. The septa were found to resemble those in the rusts rather than the type characteristic of the Tremellales and the homobasidiomycetes.
Relations between haustoria of Erysiphe graminis and host cytoplasm in cells opened by microsurgery
Authors: Sullivan Timothy P. , Bushnell W. R. , Rowell J. B.
Published: January 2008

Epidermal cells of barley (Hordeum vulgare L.), which contained haustoria of Erysiphe graminis [DC] Merat f. sp. hordei Em. Marchal, were opened with a microneedle, thereby exposing the haustorial apparatus and surviving components of the host protoplast to externally supplied osmotica. Haustoria remained alive and functional for one or more hours in the incised cell with either salt or sucrose osmotica, as indicated by growth of attached hyphae and the visible condition of the haustorium. A thin layer of host cytoplasm (the haustorial sac) remained in place around the functional haustoria. Additional host cytoplasm was seen frequently in streams, masses, or a parietal layer within 100 μm of the haustorium. The cytoplasm often migrated to the haustorium after incision and came to rest there, especially on osmotica hypertonic to the host. The amount of fungal growth after incision was positively correlated with the amount of cytoplasm near the haustorium (large amounts if cells were incised 30 μm or more from the haustorium; small amounts if cells were incised less than 10 μm from the haustorium). The times after incision that cytoplasmic organelles near the haustorium moved in streams or vibratory patterns coincided with the times after incision that hyphae grew. Most of the host cytoplasm was removed from the vicinity of the haustorium when the microneedle was swept past the haustorium repeatedly. However, the haustoria that survived in a functional condition after nearby regions of the host cell had been swept, remained enclosed by a thin layer of cytoplasm and in contact with a layer of host cytoplasm on the host wall around the haustorial neck. The results suggest that the haustorium must be in contact with small amounts of living host cytoplasm to be functional, but that the haustorium does not depend on vacuolar substances, the nucleus of the host, or cytoplasm in distant parts of the host cell.
The leaf anatomy of hemlock, Tsuga canadensis
Authors: Gambles R. L. , Dengler N. G.
Published: January 2008

Structural features related to the pathway of water movement in the leaf of hemlock, Tsuga canadensis (L.) Carr., have been examined in conjunction with investigations of plant water relations. Cell surface areas and volumes were determined by projecting 2-μm serial sections, measuring them with a map tracer, and multiplying cell perimeters by section thickness; or by the trace–cut–weigh method. Scanning electron microscope observations showed that the stomata are occluded with a continuous layer of rod-like wax particles. The average maximum distance over which water must move from the xylem of the single median bundle to the mesophyll is 770 μm, and each 40 μm of length of vein (the diameter of a mesophyll cell) supplies 196 cells. The palisade mesophyll consists of two layers, while the spongy mesophyll is arranged in sheets which radiate from the vascular bundle to the margin and alternate with large intercellular spaces. The mesophyll cell walls may provide the pathway through which the bulk of the water moves; the volume occupied by the mesophyll cell walls is 1.27 × 10−4 cm3 or 2.5% of total leaf volume. The total evaporative surface area of the mesophyll is 1.61 cm2 per leaf.
Aberrant coumarin metabolism in crown gall tumor tissue of tobacco
Authors: Brown Stewart A. , Tenniswood Martin
Published: January 2008

Cultures of normal tobacco callus tissue 3 weeks after subculture contain free and bound forms of cinnamic, caffeic, and ferulic acids and bergapten, and bound umbelliferone, esculetin, and scopoletin. Cultures of tobacco crown gall tumor tissue lack cinnamic acid, umbelliferone, and bergapten; but they contain free as well as bound esculetin and scopoletin, and higher total levels of each of these coumarins than normal tissue. It is suggested that biosynthesis of coumarins in tumor cells has been diverted from the umbelliferone–furanocoumarin pathway in favor of esculetin and scopoletin.
The effect of the Sr6 gene for host resistance on histological events during the development of stem rust in near-isogenic wheat lines
Authors: Skipp R. A. , Samborski D. J.
Published: January 2008

Seedling leaves of resistant (Sr6) and susceptible (sr6) near-isogenic wheat lines inoculated with urediospores of Puccinia graminis f. sp. tritici race C 17 (56) became infected at similar rates. Host cells of the resistant line became necrotic after haustorial penetration (beginning about 20 h after inoculation), whereas necrosis was rarely seen in the susceptible line and colonies grew to form sporulating pustules. Some colonies in the resistant line appeared to have stopped growing by about 60 h after inoculation, while others grew slowly, the area of necrosis increasing as they expanded.Inoculated resistant-line plants became susceptible when incubated at 25 °C rather than 20 °C. Provided that the plants were kept at 25 °C for at least 1 day before inoculation, no host cell became necrotic. The necrotic response was resumed, and a more resistant infection type developed when infected seedlings were transferred from 25 °C to 20 °C. The converse occurred when resistant plants were grown and incubated at 20 °C, then transferred to 25 °C.Effects on fungal growth and the action of the Sr6 gene were considered to be closely associated with host cell necrosis. Temperature sensitivity appeared to be a property of the host plant.
Studies in the Alismataceae. V. Experimental modification of phyllotaxis in pseudostolons of Echinodorus tenellus by means of growth inhibitors
Authors: Charlton W. A.
Published: January 2008

Treatment with triiodobenzoic acid (TIBA), N-dimethylamino succinamic acid (B-995), and (2-chloroethyl)trimethylammonium chloride (CCC) can modify the pattern of development of the pseudostolons of Echinodorus tenellus. In particular, CCC and B-995 can with a high degree of success suppress the normal reversal of genetic spiral of the pseudostolon. Other aspects of phyllotaxis, including phyllotaxis of lateral buds, are not affected by CCC and B-995.The pseudostolons, as previously described, are modified inflorescences bearing bracts in false whorls of three, and a vegetative bud in the axil of the first bract of each set after the first. After passing through a brief stabilizing phase the pseudostolon enters a stable state in which the direction of genetic spiral of the main axis reverses with the initiation of the second bract of each set, and in which the genetic spiral of the lateral vegetative bud is quite consistently homodromous with that of the main axis at the time of initiation of the bud.The experimental findings are discussed in relation to the earlier descriptive and analytical studies of E. tenellus. Some previously erected hypotheses relating to control of phyllotaxis in this plant are invalidated. It is suggested that in E. tenellus determination of maintenance or reversal of genetic spiral occurs within a short span of development between the initiation of the first and second bract of each set, and that direction of genetic spiral in the pseudostolon and its vegetative laterals may be controlled by mechanisms independent of those controlling other aspects of phyllotaxis such as divergence angle.
Antipodium, a new genus of Hyphomycetes
Authors: Pirozynski K. A.
Published: January 2008

A hyphomycete artificially cultured from a single ascospore of a fungus identified as Ophionectria trichospora (Berk. & Br.) Sacc. is described as Antipodium spectabile forma-gen. nov. & sp. nov.
Étude cytologique du mode d'action du capsidiol, sur les hyphes de Phytophthora capsici
Authors: Turelli Michel , Coulomb Claude , Mutaftschiev Stéphanie , Coulomb Philippe-Jean
Published: January 2008

After the action of capsidiol on the hyphae of Phytophthora capsici in vitro, observations with electron microscopy revealed alterations in the cell wall, in the plasmalemma, in the mitochondria, and in the Golgi system. Among other effects, phytoalexin stimulated the separation of the external cell wall layers, liberating a three-component filament. Such cytomorphological events were also recorded in situ on sections, when the fungus parasitized the leaves of Capsicum annuum. [Translated by the Journal]
Immunocytochemical detection of fungi in the roots of Rhododendron
Authors: Mueller W. C. , Tessier B. J. , Englander L.
Published: January 2008

Antisera were prepared from fruiting structures of a Clavaria sp. found growing in the vicinity of Rhododendron plants and from mycelium of Pezizella ericae grown in culture. The antisera were used for the detection and differentiation of fungi in thin sections of roots of Rhododendron by an indirect immunocytochemical procedure using colloidal gold-labelled goat antirabbit immunoglobin G. Three distinct fungal types could be detected in roots: hyphae that reacted only with the Clavaria antiserum; hyphae that reacted only with the Pezizella antiserum; and hyphae that did not react with either antiserum.