bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distinct Functions of Vav1 in JNK1 Activation in Jurkat T Cells Versus Non‐Haematopoietic Cells
Authors: Kaminski S. , Del Pozo M. A. , Hipskind R. A. , Altman A. , Villalba M. 
Published: June 2004

AbstractVav1, the 95‐kDa protein encoded by the vav1 proto‐oncogene, is expressed exclusively in haematopoietic cells, where it becomes phosphorylated on tyrosine residues in response to antigen receptor ligation. Vav1 was found to act as a Rac1‐specific guanine nucleotide exchange factor and to activate c‐Jun N‐terminal kinase (JNK1) in vitro and in ectopic expression systems using non‐haematopoietic cells. Here, we studied the role of Vav1 in JNK1 activation in T cells versus non‐haematopoietic cells. Vav1 overexpression activated JNK1 in COS7 and 293T cells but not in Jurkat T lymphocytes. In contrast, constitutively activated Rac1 efficiently stimulated JNK1 in both cell types under the same conditions. Vav1 did function in T cells because it clearly stimulated the activity of a nuclear factor of activated T‐cell reporter plasmid in the same cells. Moreover, Vav1 induction of JNK1 in T cells required coexpression with calcineurin. This cooperation was cell type specific because it was not observed in COS7 or 293T cells. In contrast, Vav1 did not cooperate with calcineurin to activate either extracellular signal‐regulated kinase 2 or p38. These findings demonstrate that Vav1 alone is a poor activator of the JNK1 pathway in T cells and emphasize the importance of studying the physiological functions of Vav1 in haematopoietic cells.
Identification of a Type 1 Diabetes‐Associated CD4 Promoter Haplotype with High Constitutive Activity
Authors: Kristiansen O. P. , Karlsen A. E. , Larsen Z. M. , Johannesen J. , Pociot F. , Mandrup‐Poulsen T. ,   The Danish IDDM Epidemiology and Genetics Group & The Danish Study Group of IDDM in Childhood
Published: June 2004

Abstract CD4 is a candidate gene in autoimmune diseases, including Type 1 diabetes mellitus (T1DM), because the CD4 receptor is crucial for appropriate antigen responses of CD4+ T cells. We previously found linkage between a CD4‐1188(TTTTC)5−14 promoter polymorphism and T1DM. In the present study, we screened the human CD4 promoter for mutations and identified three frequent single nucleotide polymorphisms (SNPs): CD4‐181C/G, CD4‐521C/G and CD4‐1050T/C. The SNPs are in strong linkage disequilibrium (LD) and association with the CD4‐1188(TTTTC)5−14 alleles, and we observed nine CD4 promoter haplotypes, of which four are frequent. We genotyped the SNPs in 253 Danish T1DM families (1129 individuals) and found evidence for linkage and association of a CD4 (A4‐1188T‐1050G‐521C‐181) haplotype to T1DM. In reporter studies, we show that (1) the T1DM‐associated CD4 haplotype encodes high constitutive promoter activity and (2) the CD4‐181G variant encodes higher stimulated promoter activity than the CD4‐181C variant. This difference is in part neutralized in the frequently occurring CD4 promoter haplotypes by the more upstream genetic variants. Thus, we report functional impact of a novel CD4‐181C/G SNP on stimulated CD4 promoter activity and the identification of a novel CD4 haplotype with high constitutive promoter activity that is linked and associated with T1DM.
Interleukin‐10‐Modulated Immature Dendritic Cells Control the Proinflammatory Environment in Multiple Sclerosis
Authors: Adikari S. B. , Pettersson A. , Soderstrom M. , Huang Y.‐M. , Link H. 
Published: June 2004

AbstractMultiple sclerosis (MS) is a disabling, inflammatory, demyelinating disease of the central nervous system considered to be mediated by autoreactive T cells. Dendritic cells (DC), being professional antigen‐presenting cells, play a pivotal role in the decision between T‐cell activation and anergy. It has been suggested that mature DC (mDC) induce immunity, whereas immature DC (imDC) have the potential to induce tolerance. In this study, we investigated the effects of autologous imDC versus autologous mDC on lymphocytes with respect to the expression of functionally important cell‐surface molecules and production of cytokines. Our aims were to investigate whether the maturation status of DC differs between MS and healthy controls (HC) and to explore whether the effects of DC on T‐cell responses differ between MS and HC. DC were generated from adherent blood mononuclear cells from patients with MS and HC. imDC were obtained by culture with either granulocyte–macrophage colony‐stimulating factor (GM‐CSF) + interleukin‐4 (IL‐4) or GM‐CSF + IL‐4 + IL‐10. mDC were obtained by adding lipopolysaccharide to DC cultures. Upon coculture with autologous lymphocytes, mDC activated the autologous T cells as reflected by increased CD25 and cytotoxic T‐lymphocyte antigen‐4 expression on CD4+ T cells together with the increased production of both T helper 1 (Th1) (IL‐2 and interferon‐γ) and Th2 (IL‐10 and IL‐4) cytokines. Unmodulated naïve imDC induced the production of only IL‐4. An exposure of imDC to IL‐10 induced the production of IL‐4 as well as IL‐10 by autologous lymphocytes. We hypothesize that such imDC are important in controlling the proinflammatory environment in vivo in patients with MS.
Waxy proteins and amylose content in diploid Triticeae species with genomes A, S and D
Authors: Rodriguez‐Quijano M. , Vázquez J. F. , Carrillo J. M. 
Published: June 2004

AbstractA collection of 89 accessions of diploid species of wheat was analysed for waxy protein in the grain: 39 accessions of Einkorn wheats, 41 accessions of Sitopsis section wheat and nine accessions of Triticum tauschii. The electrophoretic patterns showed low polymorphism. In each group of wheat, a single and different allele was detected. In accessions of Einkorn wheats that allele had a similar electrophoretical mobility to the Wx‐A1a allele of the bread wheat ‘Chinese Spring’, in accessions of the Sitopsis section it had a similar mobility to that of the Wx‐B1f allele of tetraploid wheat, and in the accessions of T. tauschii, it was similar to the Wx‐D1a allele of the bread wheat ‘Chinese Spring’. The accessions were also analysed for apparent amylose content. Results showed that amylose content ranged from 22 to 35% in Einkorn wheats, from 28 to 41% in the Sitopsis section and from 26 to 35% in accessions of T. tauschii.
Chromosomal location of genes for carotenoid pigments in Hordeum chilense
Authors: Atienza S. G. , Ramírez C. M. , Hernández P. , Martín A. 
Published: June 2004

AbstractIn wheat, carotenoids are very important for end‐use quality in noodle production. Hexaploid tritordeums are the amphiploids derived from the cross between a wild diploid barley (Hordeum chilense) and durum wheat. Hexaploid tritordeums exhibit a higher carotenoid content than their respective wheat parents. The cross between H1 and H7 lines of H. chilense was used in order to map quantitative trait loci (QTL) for carotenoid content. Multiple interval mapping identified one QTL mapped on chromosome 2. This knowledge is helpful to transfer this favourable trait to other cereal genomes because of the high crossability of H. chilense with other members of the tribe Triticeae.
RAPD and SCAR markers for powdery mildew resistance gene er in pea
Authors: Janila P. , Sharma B. 
Published: June 2004

AbstractIn pea, a single recessive gene (er) on linkage group 6 confers resistance to powdery mildew caused by Erysiphe pisi. The present study aims to identify molecular markers linked to the er gene. Screening of the powdery mildew‐resistant cultivar ‘DMR11’ and its susceptible nearisogenic line for polymorphism revealed linkage of two RAPD primers (OPO‐02 and OPU‐17) to the er gene and a sequence characterized polymorphic region (SCAR) primer, ScOPD‐10650 with er in a population of 83 F2 plants in the order: OPU‐17 ‐ er ‐ ScOPD‐10650 ‐ OPO‐02. The markers ScOPD‐10650 and OPU‐17 being coupled with the allele causing resistance would substantially increase the efficiency of marker‐assisted selection in peabreeding for powdery mildew.
Using Multinomial Mixture Models to Cluster Internet Traffic
Authors: Jorgensen Murray 
Published: June 2004

SummaryThe paper considers the clustering of two large sets of Internet traffic data consisting of information measured from headers of transmission control protocol packets collected on a busy arc of a university network connecting with the Internet. Packets are grouped into 'flows' thought to correspond to particular movements of information between one computer and another. The clustering is based on representing the flows as each sampled from one of a finite number of multinomial distributions and seeks to identify clusters of flows containing similar packet‐length distributions. The clustering uses the EM algorithm, and the data‐analytic and computational details are given.
Criteria for Linear Model Selection Based on Kullback's Symmetric Divergence
Authors: Cavanaugh Joseph E. 
Published: June 2004

SummaryModel selection criteria are frequently developed by constructing estimators of discrepancy measures that assess the disparity between the 'true' model and a fitted approximating model. The Akaike information criterion (AIC) and its variants result from utilizing Kullback's directed divergence as the targeted discrepancy. The directed divergence is an asymmetric measure of separation between two statistical models, meaning that an alternative directed divergence can be obtained by reversing the roles of the two models in the definition of the measure. The sum of the two directed divergences is Kullback's symmetric divergence.In the framework of linear models, a comparison of the two directed divergences reveals an important distinction between the measures. When used to evaluate fitted approximating models that are improperly specified, the directed divergence which serves as the basis for AIC is more sensitive towards detecting overfitted models, whereas its counterpart is more sensitive towards detecting underfitted models. Since the symmetric divergence combines the information in both measures, it functions as a gauge of model disparity which is arguably more balanced than either of its individual components. With this motivation, the paper proposes a new class of criteria for linear model selection based on targeting the symmetric divergence. The criteria can be regarded as analogues of AIC and two of its variants: 'corrected' AIC or AICc and 'modified' AIC or MAIC. The paper examines the selection tendencies of the new criteria in a simulation study and the results indicate that they perform favourably when compared to their AIC analogues.
Continuous‐Time Stochastic Processes with Cyclical Long‐Range Dependence
Authors: Anh V.V. , Knopova V.P. , Leonenko N.N. 
Published: June 2004

SummaryThis paper introduces continuous‐time random processes whose spectral density is unbounded at some non‐zero frequencies. The discretized versions of these processes have asymptotic properties similar to those of discrete‐time Gegenbauer processes. The paper presents some properties of the covariance function and spectral density as well as a theory of statistical estimation of the mean and covariance function of such processes. Some directions for further generalizations of the results are indicated.
Speaking of Tongues
Authors: Fussner Hannah 
Published: June 2004

AbstractIn this paper I reflect on claims that artefacts, as alternatives to texts, can provide an effective means of access to learning. With reference to the work of Walter Benjamin, I analyse the role the “aura” of a ritual object played in engaging a group of Year 6 students, all of whom experienced various degrees of delayed literacy. Drawing on Levi‐Strauss' essay “On the Effectiveness of Symbols”, I consider how far a unit of work involving aspects of a ritual against slander allowed the students to develop their understanding of how perfomative language might function.
The Rehabilitative Role of Arts Education in Prison: Accommodation or Enlightenment?
Authors: Clements Paul 
Published: June 2004

AbstractThe prisoner constituency is one of the most excluded in society. Addressing recidivism requires amongst other considerations, an enabling of these individuals to fulfil rehabilitative intent. The article argues that this necessitates an educational discourse and methodology that is embedded in concepts of emancipation and empowerment, where creativity and heuristic learning enable personal transformation. The arts are one of the agents that can naturally encourage spontaneous and participatory learning, enabling a more liberating and self‐directed rehabilitative process. Notwithstanding, arts education in prison illuminates the struggle between individual creative needs and social accommodation. Historically the shifting paradigm of penal policy has reflected a wider political intention. But there is an irony as the New Labour government that champions social inclusion has overseen the reduction of opportunity in prison to engage with the arts, replaced by an instrumental agenda concerning basic, key and cognitive skills. Furthermore, this has arguably been costly and ineffectual, hence the need to accommodate a more creative and expressive curriculum. The article has been divided into two parts. The first examines competing discourses of penal educational provision in order to assess the role of the arts. The second part examines a radical educational agenda of inclusion based on emancipatory theory, as a conduit for personal transformation, in which the creative arts have a central role.
The Status of Graphical Presentation in Interior/Architectural Design Education
Authors: Gurel Meltem O. , Basa Inci 
Published: June 2004

AbstractThis article argues that interior/architectural design education favours a dominance of final presentation over the design process in the studio environment, particularly in the evaluation of a project. It suggests that the appeal of design juries for pleasant drawings, which may shift the emphasis from the project itself to its representation, may be recognized as a discursive habit with limited contribution for educational concerns. The theoretical stance argues that the interest for graphical presentation has primarily remained within a formalist aesthetic agenda and has rarely been conceptualized beyond this convention. With this in mind a series of questions is developed in order to reform the relationship between graphical presentation and the design education process.
The Type II Protein Secretion System of
Legionella pneumophila
Promotes Growth at Low Temperatures
Authors: Söderberg Maria A. , Rossier Ombeline , Cianciotto Nicholas P. 
Published: June 2004

ABSTRACT

The gram-negative bacterium
Legionella pneumophila
grows in both natural and man-made water systems and in the mammalian lung as a facultative intracellular parasite. The PilD prepilin peptidase of
L. pneumophila
promotes type IV pilus biogenesis and type II protein secretion. Whereas pili enhance adherence,
Legionella
type II secretion is critical for intracellular growth and virulence. Previously, we observed that
pilD
transcript levels are greater in legionellae grown at 30 versus 37°C. Using a new
pilD
::
lacZ
fusion strain, we now show that
pilD
transcriptional initiation increases progressively as
L. pneumophila
is grown at 30, 25, and 17°C.
Legionella pilD
mutants also had a dramatically reduced ability to grow in broth and to form colonies on agar at the lower temperatures. Whereas strains specifically lacking type IV pili were not defective for low-temperature growth, mutations in type II secretion (
lsp
) genes greatly impaired the capacity of
L. pneumophila
to form colonies at 25, 17, and 12°C. Indeed, the
lsp
mutants were completely unable to grow at 12°C. The growth defect of the
pilD
and
lsp
mutants was complemented by reintroduction of the corresponding intact gene. Interestingly, the
lsp
mutants displayed improved growth at 25°C when plated next to a streak of wild-type but not mutant bacteria, implying that a secreted, diffusible factor promotes low-temperature growth. Mutants lacking either the known secreted acid phosphatases, lipases, phospholipase C, lysophospholipase A, or protease grew normally at 25°C, suggesting the existence of a critical, yet-to-be-defined exoprotein(s). In summary, these data document, for the first time, that
L. pneumophila
replicates at temperatures below 20°C and that a bacterial type II protein secretion system facilitates growth at low temperatures.
Regulatory Elements of theStaphylococcus aureusProtein A (Spa) Promoter
Authors: Gao Jinxin , Stewart George C. 
Published: June 2004

ABSTRACTStaphylococcal protein A (Spa) is an important virulence factor ofStaphylococcus aureus. Transcription of thespadeterminant occurs during the exponential growth phase and is repressed when the cells enter the postexponential growth phase. Regulation ofspaexpression has been found to be complicated, with regulation involving multiple factors, including Agr, SarA, SarS, SarT, Rot, and MgrA. Our understanding of how these factors work on thespapromoter to regulatespaexpression is incomplete. To identify regulatory sites within thespapromoter, analysis of deletion derivatives of the promoter in host strains deficient in one or more of the regulatory factors was undertaken, and several critical features ofsparegulation were revealed. The transcriptional start sites ofspawere determined by primer extension. Thespapromoter sequences were subcloned in front of a promoterless chloramphenicol acetyltransferase reporter gene. Various lengths ofspatruncations with the same 3′ end were constructed, and the resultant plasmids were transduced into strains with different regulatory genetic backgrounds. Our results identified upstream promoter sequences necessary for Agr system regulation ofspaexpression. Theciselements for SarS activity, an activator ofspaexpression, and for SarA activity, a repressor ofspaexpression, were identified. The well-characterized SarA consensus sequence on thespapromoter was found to be insufficient for SarA repression of thespapromoter. Full repression required the presence of a second consensus site adjacent to the SarS binding site. Sequences directly upstream of the core promoter sequence were found to stimulate transcription.
Membrane Restructuring by
Bordetella pertussis
Adenylate Cyclase Toxin, a Member of the RTX Toxin Family
Authors: Martín César , Requero M.-Asunción , Masin Jiri , Konopasek Ivo , Goñi Félix M. , Sebo Peter , Ostolaza Helena 
Published: June 2004

ABSTRACT

Adenylate cyclase toxin (ACT) is secreted by
Bordetella pertussis
, the bacterium causing whooping cough. ACT is a member of the RTX (repeats in toxin) family of toxins, and like other members in the family, it may bind cell membranes and cause disruption of the permeability barrier, leading to efflux of cell contents. The present paper summarizes studies performed on cell and model membranes with the aim of understanding the mechanism of toxin insertion and membrane restructuring leading to release of contents. ACT does not necessarily require a protein receptor to bind the membrane bilayer, and this may explain its broad range of host cell types. In fact, red blood cells and liposomes (large unilamellar vesicles) display similar sensitivities to ACT. A varying liposomal bilayer composition leads to significant changes in ACT-induced membrane lysis, measured as efflux of fluorescent vesicle contents. Phosphatidylethanolamine (PE), a lipid that favors formation of nonlamellar (inverted hexagonal) phases, stimulated ACT-promoted efflux. Conversely, lysophosphatidylcholine, a micelle-forming lipid that opposes the formation of inverted nonlamellar phases, inhibited ACT-induced efflux in a dose-dependent manner and neutralized the stimulatory effect of PE. These results strongly suggest that ACT-induced efflux is mediated by transient inverted nonlamellar lipid structures. Cholesterol, a lipid that favors inverted nonlamellar phase formation and also increases the static order of phospholipid hydrocarbon chains, among other effects, also enhanced ACT-induced liposomal efflux. Moreover, the use of a recently developed fluorescence assay technique allowed the detection of trans-bilayer (flip-flop) lipid motion simultaneous with efflux. Lipid flip-flop further confirms the formation of transient nonlamellar lipid structures as a result of ACT insertion in bilayers.
Mutational Analysis of the
Myxococcus xanthus
Ω4499 Promoter Region Reveals Shared and Unique Properties in Comparison with Other C-Signal-Dependent Promoters
Authors: Yoder Deborah R. , Kroos Lee 
Published: June 2004

ABSTRACT

The bacterium
Myxococcus xanthus
undergoes multicellular development during times of nutritional stress and uses extracellular signals to coordinate cell behavior. C-signal affects gene expression late in development, including that of Ω4499, an operon identified by insertion of Tn
5 lac
into the
M. xanthus
chromosome. The Ω4499 promoter region has several sequences in common with those found previously to be important for expression of other C-signal-dependent promoters. To determine if these sequences are important for Ω4499 promoter activity, the effects of mutations on expression of a downstream reporter gene were tested in
M. xanthus
. Although the promoter resembles those recognized by
Escherichia coli
σ
54
, mutational analysis implied that a σ
70
-type σ factor likely recognizes the promoter. A 7-bp sequence known as a C box and a 5-bp element located 6 bp upstream of the C box have been shown to be important for expression of other C-signal-dependent promoters. The Ω4499 promoter region has C boxes centered at −33 and −55 bp, with 5-bp elements located 7 and 8 bp upstream, respectively. A multiple-base-pair mutation in any of these sequences reduced Ω4499 promoter activity more than twofold. Single base-pair mutations in the C box centered at −33 bp yielded a different pattern of effects on expression than similar mutations in other C boxes, indicating that each functions somewhat differently. An element from about −81 to −77 bp exerted a twofold positive effect on expression but did not appear to be responsible for the C-signal dependence of the Ω4499 promoter. Mutations in
sigD
and
sigE
, which are genes that encode σ factors, reduced expression from the Ω4499 promoter. The results provide further insight into the regulation of C-signal-dependent genes, demonstrating both shared and unique properties among the promoter regions so far examined.
Role of RepA and DnaA Proteins in the Opening of the Origin of DNA Replication of an IncB Plasmid
Authors: Betteridge T. , Yang J. , Pittard A. J. , Praszkier J. 
Published: June 2004

ABSTRACT

The replication initiator protein RepA of the IncB plasmid pMU720 was shown to induce localized unwinding of its cognate origin of replication in vitro. DnaA, the initiator protein of
Escherichia coli
, was unable to induce localized unwinding of this origin of replication on its own but enhanced the opening generated by RepA. The opened region lies immediately downstream of the last of the three binding sites for RepA (RepA boxes) and covers one turn of DNA helix. A 6-mer sequence, 5′-TCTTAA-3′, which lies within the opened region, was essential for the localized unwinding of the origin in vitro and origin activity in vivo. In addition, efficient unwinding of the origin of replication of pMU720 in vitro required the native positioning of the binding sites for the initiator proteins. Interestingly, binding of RepA to RepA box 1, which is essential for origin activity, was not required for the localized opening of the origin in vitro.