bluuebunny/crossref_metadata_2025 huggingface dataset:
Two-domain reconstitution of a functional protein histidine kinase
Authors: Park Heiyoung , Saha Soumitra K. , Inouye Masayori
Published: July 2002

In prokaryotes, in the absence of protein serine/threonine/tyrosine kinases, protein histidine kinases play a major role in signal transduction involved in cellular adaptation to various environmental changes and stresses. Histidine kinases phosphorylate their cognate response regulators at a specific aspartic acid residue with ATP in response to particular environmental signals. In this His-Asp phosphorelay signal transduction system, it is still unknown how the histidine kinase exerts its enzymatic function. Here we demonstrate that the cytoplasmic kinase domain of EnvZ, a transmembrane osmosensor of
Escherichia coli
can be further divided into two distinct functional subdomains: subdomain A [EnvZ(C)⋅(223–289); 67 residues] and subdomain B [EnvZ(C)⋅(290–450); 161 residues]. Subdomain A, with a high helical content, contains the autophosphorylation site, H–243, and forms a stable dimer having the recognition site for OmpR, the cognate response regulator of EnvZ. Subdomain B, an α/β-protein, exists as a monomer. When mixed, the two subdomains reconstitute the kinase function to phosphorylate subdomain A at His-243 in the presence of ATP. Subsequently, the phosphorylated subdomain A is able to transfer its phosphate group to OmpR. The two-domain structure of this histidine kinase provides an insight into the structural arrangement of the enzyme and its transphosphorylation mechanism.
Nanobacteria: An alternative mechanism for pathogenic intra- and extracellular calcification and stone formation
Authors: Kajander E. Olavi , Çiftçioglu Neva
Published: July 2002

Calcium phosphate is deposited in many diseases, but formation mechanisms remain speculative. Nanobacteria are the smallest cell-walled bacteria, only recently discovered in human and cow blood and commercial cell culture serum. In this study, we identified with energy-dispersive x-ray microanalysis and chemical analysis that all growth phases of nanobacteria produce biogenic apatite on their cell envelope. Fourier transform IR spectroscopy revealed the mineral as carbonate apatite. The biomineralization in cell culture media resulted in biofilms and mineral aggregates closely resembling those found in tissue calcification and kidney stones. In nanobacteria-infected fibroblasts, electron microscopy revealed intra- and extracellular acicular crystal deposits, stainable with von Kossa staining and resembling calcospherules found in pathological calcification. Previous models for stone formation have led to an hypothesis that elevated pH due to urease and/or alkaline phosphatase activity is a lithogenic factor. Our results indicate that carbonate apatite can be formed without these factors at pH 7.4, at physiological phosphate and calcium concentrations. Nanobacteria can produce apatite in media mimicking tissue fluids and glomerular filtrate and provide a unique model for
in vitro
studies on calcification.
Endothelial cell death, angiogenesis, and microvascular function after castration in an androgen-dependent tumor: Role of vascular endothelial growth factor
Authors: Jain Rakesh K. , Safabakhsh Nina , Sckell Axel , Chen Yi , Jiang Ping , Benjamin Laura , Yuan Fan , Keshet Eli
Published: July 2002

The sequence of events that leads to tumor vessel regression and the functional characteristics of these vessels during hormone–ablation therapy are not known. This is because of the lack of an appropriate animal model and monitoring technology. By using
in vivo
microscopy and
in situ
molecular analysis of the androgen-dependent Shionogi carcinoma grown in severe combined immunodeficient mice, we show that castration of these mice leads to tumor regression and a concomitant decrease in vascular endothelial growth factor (VEGF) expression. Androgen withdrawal is known to induce apoptosis in Shionogi tumor cells. Surprisingly, tumor endothelial cells begin to undergo apoptosis before neoplastic cells, and rarefaction of tumor vessels precedes the decrease in tumor size. The regressing vessels begin to exhibit normal phenotype, i.e., lower diameter, tortuosity, vascular permeability, and leukocyte adhesion. Two weeks after castration, a second wave of angiogenesis and tumor growth begins with a concomitant increase in VEGF expression. Because human tumors often relapse following hormone–ablation therapy, our data suggest that these patients may benefit from combined anti-VEGF therapy.
A novel glucose-responsive element in the human insulin gene functions uniquely in primary cultured islets
Authors: Sander Maike , Griffen Steven C. , Huang Juemin , German Michael S.
Published: July 2002

Insulin gene transcription is limited to the beta cells within the mammalian pancreas and, like insulin secretion, is regulated by glucose. Our previous studies in primary cultured beta cells suggested the presence of a strong glucose-responsive enhancer element between base pairs −341 and −260 of the human insulin promoter, the same region in which a transcriptional repressor had been identified in beta-cell tumor lines. In an attempt to map these promoter activities and resolve these conflicting data, we designed minienhancer constructs spanning this region, and tested them in primary cultured and immortalized cells. One sequence, the Z element (base pairs −292 to −243), functions as both a potent glucose-responsive transcriptional enhancer in primary cultured islet cells and as a transcriptional repressor in immortalized beta and nonbeta cells and in primary fibroblasts. In addition, the Z element binds a novel glucose-responsive protein complex that is found in the nuclei of primary cultured islet cells, but not in the nuclei of tumor cells or primary cultured fibroblasts. These data demonstrate a critical role for the Z element in human insulin gene transcription and its regulation by glucose.
Alanine, not ammonia, is excreted from N
2
-fixing soybean nodule bacteroids
Authors: Waters James K. , Hughes Bobby L. , Purcell Larry C. , Gerhardt Klaus O. , Mawhinney Thomas P. , Emerich David W.
Published: July 2002

Symbiotic nitrogen fixation, the process whereby nitrogen-fixing bacteria enter into associations with plants, provides the major source of nitrogen for the biosphere. Nitrogenase, a bacterial enzyme, catalyzes the reduction of atmospheric dinitrogen to ammonium. In rhizobia-leguminous plant symbioses, the current model of nitrogen transfer from the symbiotic form of the bacteria, called a bacteroid, to the plant is that nitrogenase-generated ammonia diffuses across the bacteroid membrane and is assimilated into amino acids outside of the bacteroid. We purified soybean nodule bacteroids by a procedure that removed contaminating plant proteins and found that alanine was the major nitrogen-containing compound excreted. Bacteroids incubated in the presence of
15
N
2
excreted alanine highly enriched in
15
N. The ammonium in these assays neither accumulated significantly nor was enriched in
15
N. The results demonstrate that a transport mechanism rather than diffusion functions at this critical step of nitrogen transfer from the bacteroids to the plant host. Alanine may serve only as a transport species, but this would permit physiological separation of the transport of fixed nitrogen from other nitrogen metabolic functions commonly mediated through glutamate.
In vivoantagonism of a T cell response by an endogenously expressed ligand
Authors: Basu Devraj , Williams Calvin B. , Allen Paul M.
Published: July 2002

3.L2 T cell receptor transgenic T cells are activated by the 64–76 peptide of the mouse hemoglobin d β chain [Hb(64–76)], and their response is antagonized by the position 72 alanine substitution of this peptide (A72). To test the effect of this altered peptide ligand (APL) on 3.L2 T cell functionin vivo, a transgene expressing A72 in major histocompatibility complex II positive cells (A72tg) has been introduced into mice. We demonstrate that 3.L2 T cells, when transferred to A72tg+mice show a dramatically reduced proliferative response to Hb(64–76). Identical decreased responses were observed using T cells that developed in either A72tg+or A72tg−hosts. This affect was not attributable to diminished precursor frequency, anergy, or competition for binding to I-Ekmolecules. These results unequivocally demonstratein vivoantagonism by an endogenous APL and characterize a class of self-peptides that, although inefficient in causing deletion in the thymus, effectively modulate T cell responses in the periphery.
Gene rearrangement attenuates expression and lethality of a nonsegmented negative strand RNA virus
Authors: Wertz Gail Williams , Perepelitsa Victoria P. , Ball L. Andrew
Published: July 2002

The nonsegmented negative strand RNA viruses comprise hundreds of human, animal, insect, and plant pathogens. Gene expression of these viruses is controlled by the highly conserved order of genes relative to the single transcriptional promoter. We utilized this regulatory mechanism to alter gene expression levels of vesicular stomatitis virus by rearranging the gene order. This report documents that gene expression levels and the viral phenotype can be manipulated in a predictable manner. Translocation of the promoter–proximal nucleocapsid protein gene N, whose product is required stoichiometrically for genome replication, to successive positions down the genome reduced N mRNA and protein expression in a stepwise manner. The reduction in N gene expression resulted in a stepwise decrease in genomic RNA replication. Translocation of the N gene also attenuated the viruses to increasing extents for replication in cultured cells and for lethality in mice, without compromising their ability to elicit protective immunity. Because monopartite negative strand RNA viruses have not been reported to undergo homologous recombination, gene rearrangement should be irreversible and may provide a rational strategy for developing stably attenuated live vaccines against this type of virus.
In vivo
function of mutated spliced leader RNAs in
Caenorhabditis elegans
Authors: Xie Hongying , Hirsh David
Published: July 2002

The role of spliced leader RNA (SL RNA) in trans-splicing in
Caenorhabditis elegans
has been studied through a combination of
in vitro
mutagenesis and
in vivo
complementation of
rrs-1
mutant nematodes, which lack endogenous SL1 RNA. Three classes of mutant SL1 RNAs have been found—those that rescue the lethal phenotype at low concentration of transforming DNA, those that rescue at high but not low concentration, and those that do not rescue at all. These studies showed that some mutations in the otherwise highly conserved 22-nt spliced leader are tolerated for splicing and post-splicing events. A longer spliced leader also can be tolerated but only when present in high copy number. Changes in the first 16 nucleotides result in the appearance of no SL RNA, consistent with the
in vitro
studies by others showing that the SL1 RNA promoter partly resides within the spliced leader sequence.
Acetylation at Lys-92 enhances signaling by the chemotaxis response regulator protein CheY
Authors: Ramakrishnan Ranjani , Schuster Martin , Bourret Robert B.
Published: July 2002

When
Escherichia coli
cells lacking all chemotaxis proteins except the response regulator CheY are exposed to acetate, clockwise flagellar rotation results, indicating the acetate stimulus has activated signaling by CheY. Acetate can be converted to acetyl-CoA by either of two different metabolic pathways, which proceed through acetyl phosphate or acetyl-AMP intermediates. In turn, CheY can be covalently modified by either intermediate
in vitro
, leading to phosphorylation or acetylation, respectively. Either pathway is sufficient to support the CheY-mediated response to acetate
in vivo
. Whereas phosphorylation of Asp-57 is a recognized mechanism for activation of CheY to stimulate clockwise flagellar rotation, acetylation of CheY is less well characterized. We found evidence for multiple CheY acetylation sites by mass spectrometry and directly identified Lys-92 and Lys-109 as acetylation sites by Edman degradation of peptides from [
14
C]acetate-labeled CheY. Replacement of CheY Lys-92, the preferred acetylation site, with Arg has little effect on chemotaxis but completely prevents the response to acetate via the acetyl-AMP pathway. Thus acetylation of Lys-92 activates clockwise signaling by CheY
in vivo.
The mechanism by which acetylation activates CheY apparently is not simple charge neutralization, nor does it involve enhanced binding to the FliM flagellar switch protein. Thus acetylation probably affects signal generation by CheY at a step after switch binding.
Comparative structural analysis of transcriptionally competent and incompetent rotavirus-antibody complexes
Authors: Lawton Jeffrey A. , Estes Mary K. , Prasad B. V. Venkataram
Published: July 2002

During genome transcription in rotavirus, as with many segmented double-stranded RNA viruses, mRNA is transcribed within the intact subviral particle and translocated through specific channels in the capsid. To understand how the conformation of the capsid affects the efficiency of transcriptional events in the viral core, we carried out a series of comparative structural and biochemical studies to characterize four different structural forms of the virus exhibiting differing transcriptional behavior. Two of these were virus-antibody complexes having contrasting transcriptional capabilities, and two were variant structural forms of the virus that exist during the life cycle and also exhibit contrasting transcriptional behavior. Three-dimensional structural studies using electron cryomicroscopy showed that the binding of one Fab (8H2/G5) does not affect the conformation of the capsid, and the efficiency of mRNA production is similar to that of the native subviral particle. The other Fab (2A11/E9) introduces conformational changes in the capsid similar to those seen in the transcriptionally incompetent mature particle. In both of the transcriptionally incompetent particle types, mRNA synthesis was arrested after limited elongation with the resulting oligonucleotide transcripts remaining trapped inside the particles. Our results indicate that the continuous translocation of nascent mRNA through the capsid is critical for efficient transcript elongation and that the blockage of translocation causes premature termination of transcription.
Secretin PulD: Association with pilot PulS, structure, and ion-conducting channel formation
Authors: Nouwen Nico , Ranson Neil , Saibil Helen , Wolpensinger Bettina , Engel Andreas , Ghazi Alexandre , Pugsley Anthony P.
Published: July 2002

The outer membrane protein PulD (secretin) of
Klebsiella oxytoca
is required for transport of pullulanase across this membrane. We have purified a multimeric PulD complex from an
Escherichia coli
strain expressing all the proteins involved in pullulanase secretion. The outer membrane-anchored lipoprotein PulS was found to copurify with PulD. The molar ratio of the two proteins is close to 1:1, and the size of the complex is ≈1 MDa. Scanning transmission electron and cryo-electron microscopy analyses showed that the purified complex is a cylindrical structure having a central cavity of ≈7.6 nm and peripheral radial spokes. Fusion of proteoliposomes containing the purified complex with a planar lipid bilayer resulted in the appearance of small, voltage-activated, ion-conducting channels. We conclude that the central cavity seen in the electron microscope is part of a large gated channel and propose that the observed current fluctuations correspond to voltage-induced, relatively minor displacements of domains in the purified complex rather than to a complete opening of the secretin channel.
Defective CTLA-4 cycling pathway in Chediak–Higashi syndrome: A possible mechanism for deregulation of T lymphocyte activation
Authors: Barrat Franck J. , Le Deist Françoise , Benkerrou Malika , Bousso Philippe , Feldmann Jérome , Fischer Alain , de Saint Basile Geneviève
Published: July 2002

Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4, also known as CD152) has been shown to play a major role in the regulation of T cell activation. Its membrane expression is highly regulated by endocytosis and trafficking through the secretory lysosome pathway. Chediak–Higashi syndrome (CHS) is an inherited disorder caused by mutations in the lysosomal trafficking regulator gene,LYST. It results in defective membrane targeting of the proteins present in secretory lysosomes, and it is associated with a variety of features, including a lymphoproliferative syndrome with hemophagocytosis. The murine equivalent of CHS,beigemice, present similar characteristics but do not develop the lymphoproliferative syndrome. We show herein that CTLA-4 is present in enlarged, abnormal vesicles in CHS T cells and is not properly expressed at the cell surface after T cell activation, whereas its surface expression is not impaired. It is therefore proposed that the defective surface expression of CTLA-4 by CHS T cells is involved in the generation of lymphoproliferative disease. This observation may provide insight into the role of CTLA-4 in humans.
The crystal structure of anthranilate synthase from
Sulfolobus solfataricus
: Functional implications
Authors: Knöchel Thorsten , Ivens Andreas , Hester Gerko , Gonzalez Ana , Bauerle Ronald , Wilmanns Matthias , Kirschner Kasper , Jansonius Johan N.
Published: July 2002

Anthranilate synthase catalyzes the synthesis of anthranilate from chorismate and glutamine and is feedback-inhibited by tryptophan. The enzyme of the hyperthermophile
Sulfolobus solfataricus
has been crystallized in the absence of physiological ligands, and its three-dimensional structure has been determined at 2.5-Å resolution with x-ray crystallography. It is a heterotetramer of anthranilate synthase (TrpE) and glutamine amidotransferase (TrpG) subunits, in which two TrpG:TrpE protomers associate mainly via the TrpG subunits. The small TrpG subunit (195 residues) has the known “triad” glutamine amidotransferase fold. The large TrpE subunit (421 residues) has a novel fold. It displays a cleft between two domains, the tips of which contact the TrpG subunit across its active site. Clusters of catalytically essential residues are located inside the cleft, spatially separated from clustered residues involved in feedback inhibition. The structure suggests a model in which chorismate binding triggers a relative movement of the two domain tips of the TrpE subunit, activating the TrpG subunit and creating a channel for passage of ammonia toward the active site of the TrpE subunit. Tryptophan presumably blocks this rearrangement, thus stabilizing the inactive states of both subunits. The structure of the TrpE subunit is a likely prototype for the related enzymes 4-amino 4-deoxychorismate synthase and isochorismate synthase.
The plasminogen activator inhibitor-2 gene is not required for normal murine development or survival
Authors: Dougherty Kristiann M. , Pearson Julia M. , Yang Angela Y. , Westrick Randal J. , Baker Mark S. , Ginsburg David
Published: July 2002

Plasminogen activator inhibitor-2 (PAI-2), a member of the serpin gene family, is thought to serve as a primary regulator of plasminogen activation in the extravascular compartment. High levels of PAI-2 are found in keratinocytes, monocytes, and the human trophoblast, the latter suggesting a role in placental maintenance or embryo development. The primarily intracellular distribution of PAI-2 also may indicate a unique regulatory role in a protease-dependent cellular process such as apoptosis. To examine the potential functions of PAI-2in vivo, we generated PAI-2-deficient mice by gene targeting in embryonic stem cells. Homozygous PAI-2-deficient mice exhibited normal development, survival, and fertility and were also indistinguishable from normal controls in response to a bacterial infectious challenge or endotoxin infusion. No differences in monocyte recruitment into the peritoneum were observed after thioglycollate injection. Epidermal wound healing was equivalent among PAI-2 −/− null and control mice. Finally, crossing PAI-2 −/− with PAI-1 −/− mice to generate animals deficient in both plasminogen activator inhibitors failed to uncover an overlap in function between these two related proteins.
Telomeres of polytene chromosomes in a ciliated protozoan terminate in duplex DNA loops
Authors: Murti K. G. , Prescott D. M.
Published: July 2002

The end of a telomeric DNA sequence isolated from a polytene chromosome of a hypotrichous ciliate folds back and hybridizes with downstream telomeric sequence to form a t loop that is stable in the absence of protein and DNA cross-linking. The single-stranded, telomeric DNA sequence at the end of a macronuclear molecule does not form a t loop but, instead, is complexed with a heterodimeric, telomere-binding protein. Thus, two mechanisms for capping the ends of DNA molecules are used in the same cell.
Immunomodulation of experimental autoimmune encephalomyelitis by oral administration of copolymer 1
Authors: Teitelbaum Dvora , Arnon Ruth , Sela Michael
Published: July 2002

The activity of copolymer 1 (Cop 1, Copaxone, glatiramer acetate) in suppressing experimental autoimmune encephalomyelitis (EAE) and in the treatment of multiple sclerosis patients when injected parenterally has been extensively demonstrated. In the present study we addressed the question of whether Cop 1 can induce oral tolerance to EAE similar to myelin basic protein (MBP). We now have demonstrated that oral Cop 1 inhibited EAE induction in both rats and mice. Furthermore, oral Cop 1 was more effective than oral MBP in suppressing EAE in rats. The beneficial effect of oral Cop 1 was found to be associated with specific inhibition of the proliferative and Th1 cytokine secretion responses to MBP of spleen cells from Cop 1-fed mice and rats. In all of these assays, oral Cop 1 was more effective than oral MBP. The tolerance induced by Cop 1 could be adoptively transferred with spleen cells from Cop 1-fed animals. Furthermore, Cop 1-specific T cell lines, which inhibit EAE inductionin vivo, could be isolated from the above spleen cells. These T cell lines secrete the anti-inflammatory cytokines IL-10 and transforming growth factor type β, but not IL-4, in response to both Cop 1 and MBP. In conclusion, oral Cop 1 has a beneficial effect on the development of EAE that is associated with down-regulation of T cell immune responses to MBP and is mediated by Th2/3 type regulatory cells. These results suggest that oral administration of Cop 1 may modulate multiple sclerosis as well.
V-Amylose at atomic resolution: X-ray structure of a cycloamylose with 26 glucose residues (cyclomaltohexaicosaose)
Authors: Gessler Katrin , Usón Isabel , Takaha Takeshi , Krauss Norbert , Smith Steven M. , Okada Shigetaka , Sheldrick George M. , Saenger Wolfram
Published: July 2002

The amylose fraction of starch occurs in double-helical A- and B-amyloses and the single-helical V-amylose. The latter contains a channel-like central cavity that is able to include molecules, “iodine’s blue” being the best-known representative. Molecular models of these amylose forms have been deduced by solid state
13
C cross-polarization/magic angle spinning NMR and by x-ray fiber and electron diffraction combined with computer-aided modeling. They remain uncertain, however, as no structure at atomic resolution is available. We report here the crystal structure of a hydrated cycloamylose containing 26 glucose residues (cyclomaltohexaicosaose, CA26), which has been determined by real/reciprocal space recycling starting from randomly positioned atoms or from an oriented diglucose fragment. This structure provides conclusive evidence for the structure of V-amylose, as the macrocycle of CA26 is folded into two short left-handed V-amylose helices in antiparallel arrangement and related by twofold rotational pseudosymmetry. In the V-helices, all glucose residues are in
syn
orientation, forming systematic interglucose O(3)

n

⋅⋅⋅O(2)

n

+l
and O(6)

n

⋅⋅⋅O(2)

n

+6
/O(3)

n

+6
hydrogen bonds; the central cavities of the V-helices are filled by disordered water molecules. The folding of the CA26 macrocycle is characterized by typical “band-flips” in which diametrically opposed glucose residues are in
anti
rather than in the common
syn
orientation, this conformation being stabilized by interglucose three-center hydrogen bonds with O(3)

n

as donor and O(5)

n

+l
, O(6)

n

+l
as acceptors. The structure of CA26 permitted construction of an idealized V-amylose helix, and the band-flip motif explains why V-amylose crystallizes readily and may be packed tightly in seeds.
Mucosal vaccination overcomes the barrier to recombinant vaccinia immunization caused by preexisting poxvirus immunity
Authors: Belyakov Igor M. , Moss Bernard , Strober Warren , Berzofsky Jay A.
Published: July 2002

Overcoming preexisting immunity to vaccinia virus in the adult population is a key requirement for development of otherwise potent recombinant vaccinia vaccines. Based on our observation that s.c. immunization with vaccinia induces cellular and antibody immunity to vaccinia only in systemic lymphoid tissue and not in mucosal sites, we hypothesized that the mucosal immune system remains naive to vaccinia and therefore amenable to immunization with recombinant vaccinia vectors despite earlier vaccinia exposure. We show that mucosal immunization of vaccinia-immune BALB/c mice with recombinant vaccinia expressing HIV gp160 induced specific serum antibody and strong HIV-specific cytotoxic T lymphocyte responses. These responses occurred not only in mucosal but also in systemic lymphoid tissue, whereas systemic immunization was ineffective under these circumstances. In this context, intrarectal immunization was more effective than intranasal immunization. Boosting with a second dose of recombinant vaccinia was also more effective via the mucosal route. The systemic HIV-specific cytotoxic T lymphocyte response was enhanced by coadministration of IL-12 at the mucosal site. These results also demonstrate the independent compartmentalization of the mucosal versus systemic immune systems and the asymmetric trafficking of lymphocytes between them. This approach to circumvent previous vaccinia immunity may be useful for induction of protective immunity against infectious diseases and cancer in the sizable populations with preexisting immunity to vaccinia from smallpox vaccination.
Virulence and transmission success of the malarial parasite
Plasmodium falciparum
Authors: Hayward Rhian E. , Tiwari Bela , Piper Karen P. , Baruch Dror I. , Day Karen P.
Published: July 2002

Virulence of
Plasmodium falciparum
is associated with the expression of variant surface antigens designated PfEMP1 (
P. falciparum
erythrocyte membrane protein 1) that are encoded by a family of
var
genes. Data presented show that the transmission stages of
P. falciparum
also express PfEMP1 variants. Virulence in this host–parasite system can be considered a variable outcome of optimizing the production of sexual transmission stages from the population of disease-inducing asexual stages. Immunity to PfEMP1 will contribute to the regulation of this trade-off by controlling the parasite population with potential to produce mature transmission stages.
Adenoviral and adeno-associated viral transfer of genes to the peripheral nervous system
Authors: Glatzel Markus , Flechsig Eckhard , Navarro Beatriz , Klein Michael A. , Paterna Jean C. , Büeler Hansruedi , Aguzzi Adriano
Published: July 2002

Targeted expression of foreign genes to the peripheral nervous system is interesting for many applications, including gene therapy of neuromuscular diseases, neuroanatomical studies, and elucidation of mechanisms of axonal flow. Here we describe a microneurosurgical technique for injection of replication-defective viral vectors into dorsal root ganglia (DRG). Adenovirus- and adeno-associated virus-based vectors with transcriptional competence for DRG neurons led to expression of the gene of interest throughout the first neuron of the sensory system, from the distal portions of the respective sensory nerve to the ipsilateral nucleus gracilis and cuneatus, which contains the synapses to the spinothalamic tracts. Use of Rag-1 ablated mice, which lack all B and T lymphocytes, allowed for sustained expression for periods exceeding 100 days. In immunocompetent mice, long-term (52 days) expression was achieved with similar efficiency by using adeno-associated viral vectors. DRG injection was vastly superior to intraneural injection into the sciatic nerve, which mainly transduced Schwann cells in the vicinity of the site of inoculation site but only inefficiently transduced nerve fibers, whereas i.m. injection did not lead to any significant expression of the reporter gene in nerve fibers. The versatile and efficient transduction of genes of interest should enable a wide variety of functional studies of peripheral nervous system pathophysiology.
Explaining the moon illusion
Authors: Kaufman Lloyd , Kaufman James H.
Published: July 2002

An old explanation of the moon illusion holds that various cues place the horizon moon at an effectively greater distance than the elevated moon. Although both moons have the same angular size, the horizon moon must be perceived as larger. More recent explanations hold that differences in accommodation or other factors cause the elevated moon to appear smaller. As a result of this illusory difference in size, the elevated moon appears to be more distant than the horizon moon. These two explanations, both based on the geometry of stereopsis, lead to two diametrically opposed hypotheses. That is, a depth interval at a long distance is associated with a smaller binocular disparity, whereas an equal depth interval at a smaller distance is associated with a larger disparity. We conducted experiments involving artificial moons and confirmed the hypothesis that the horizon moon is at a greater perceptual distance. Moreover, when a moon of constant angular size was moved closer it was also perceived as growing smaller, which is consistent with the older explanation. Although Emmert's law does not predict the size–distance relationship over long distances, we conclude that the horizon moon is perceived as larger because the perceptual system treats it as though it is much farther away. Finally, we observe that recent explanations substitute perceived size for angular size as a cue to distance. Thus, they imply that perceptions cause perceptions.
Genetic reconstitution of systemic lupus erythematosus immunopathology with polycongenic murine strains
Authors: Morel Laurence , Croker Byron P. , Blenman Kim R. , Mohan Chandra , Huang Guanling , Gilkeson Gary , Wakeland Edward K.
Published: July 2002

We previously produced three congenic strains carrying lupus susceptibility genes (Sle1-Sle3) from the lupus-prone NZM2410 mouse on the C57BL/6 background and characterized their component phenotypes.Sle1mediates the loss of tolerance to nuclear antigens;Sle2lowers the activation threshold of B cells; andSle3mediates a dysregulation of CD4+T cells. We have now created a collection of bi- and tricongenic strains with these intervals and assessed the autoimmune phenotypes they elicit in various combinations. Our results indicate thatSle1is key for the development of fatal lupus. The combination ofSle1withSle2,Sle3, or the BXSB-derived autoimmune accelerating geneyaaresults in the development of systemic autoimmunity with variably penetrant severe glomerulonephritis culminating in kidney failure. In contrast, two locus combinations ofSle2,Sle3, andyaafailed to mediate fatal disease. These results indicate that the loss of tolerance to chromatin mediated bySle1is essential for disease pathogenesis and identify the pathway occupied bySle1as a strategic target for therapeutic intervention in systemic lupus erythematosus. The coexpression ofSle1,Sle2, andSle3as a B6-triple congenic results in severe systemic autoimmunity and fully penetrant, fatal glomerulonephritis. These results demonstrate the fulfillment of the genetic equivalent of Koch's postulate, where susceptibility loci in a lupus-prone strain have been identified by a genome scan, isolated and functionally characterized by congenic dissection, and finally shown to mediate full disease expression when recombined in a normal genome.
Production of resistant HIV mutants during antiretroviral therapy
Authors: Ribeiro Ruy M. , Bonhoeffer Sebastian
Published: July 2002

HIV drug therapy often fails because of the appearance of multidrug-resistant virus. There are two possible scenarios for the outgrowth of multidrug-resistant virus in response to therapy. Resistant virus may preexist at low frequencies in drug-naïve patients and is rapidly selected in the presence of drugs. Alternatively, resistant virus is absent at the start of therapy but is generated by residual viral replication during therapy. Currently available experimental methods are generally too insensitive to distinguish between these two scenarios. Here we use deterministic and stochastic models to investigate the origin of multidrug resistance. We quantify the probabilities that resistant mutants preexist, and that resistant mutants are generated during therapy. The models suggest that under a wide range of conditions, treatment failure is most likely caused by the preexistence of resistant mutants.
The quorum-sensing transcriptional regulator TraR requires its cognate signaling ligand for protein folding, protease resistance, and dimerization
Authors: Zhu Jun , Winans Stephen C.
Published: July 2002

Complexes between the quorum-sensing regulator TraR and its
inducing ligand autoinducer (AAI) are soluble in
Escherichia
coli
, whereas apo-TraR is almost completely insoluble. Here we
show that the lack of soluble TraR is due in large part to rapid
proteolysis, inasmuch as apo-TraR accumulated to high levels in an
E. coli
strain deficient in Clp and Lon proteases. In
pulse labeling experiments, AAI protected TraR against proteolysis only
when it was added before the radiolabel. This observation indicates
that TraR proteins can productively bind AAI only during their own
synthesis on polysomes, whereas fully synthesized apo-TraR proteins are
not functional AAI receptors. Purified apo-TraR was rapidly degraded by
trypsin to oligopeptides, whereas TraR–AAI complexes were more
resistant to trypsin and were cleaved at discrete interdomain linkers,
indicating that TraR requires AAI to attain its mature tertiary
structure. TraR–AAI complexes eluted from a gel filtration column as
dimers and bound DNA as dimers. In contrast, apo-TraR was monomeric,
and incubation with AAI under a variety of conditions did not cause
dimerization. We conclude that AAI is critical for the folding of
nascent TraR protein into its mature tertiary structure and that
full-length apo-TraR cannot productively bind AAI and is consequently
targeted for rapid proteolysis.
Impact du type de buts et du sentiment d'auto‐efficaciaté sur l'autorégulation et la performance dans une tâche cognitive
Authors: Vezeau Carole , Bouffard Thérèse , Tétreault Francine
Published: July 2002

Cette étude examine deux hypothèses issues des modèles théoriques portant sur l'importance des buts de performance et des buts d'apprentissage dans le fonctionnement cognitif. La première propose que comparée à une personne qui se préoccupe peu de ses performances, celle qui s'en préoccupe beaucoup devrait avoir un sentiment d'auto‐efficacité plus faible devant une tâche nouvelle. La seconde propose que l'association entre une forte préoccupation pour sa performance et un sentiment d'auto‐efficacité faible a un impact négatif sur l'autorégulation et la performance de la personne dans une tâche. Cent vingt‐huit élèves de sexe féminin ont d'abord répondu au questionnaire permettant de mesurer leurs buts de performance et d'apprentissage. Par la suite, toutes ont été revues individuellement pour résoudre une tâche d'identification de formation de concepts verbaux pour laquelle elles ont spécifié leur sentiment d'auto‐efficacité et durant laquelle divers indices d'autorégulation ont été observés ainsi que leur performance. Les résultats de cette étude vont à rencontre de la première hypothèse et montrent que les élèves se préoccupant beaucoup de leur performance ont un sentiment d'auto‐efficacité plus élevé que celles peu préoccupées par celle‐ci. En outre, aucun effet d'interaction entre le sentiment d'auto‐efficacité et les buts de performance n'a été trouvé sur l'autorégulation et la performance. Dans l'ensemble, les résultats montrent que le sentiment d'auto‐efficacité constitue le déterminant proximal de la qualité de l'autorégulation exercée et de la performance obtenue dans la tâche. La discussion met l'accent sur le rôle que jouent dans le fonctionnement cognitif le sentiment d'auto‐efficacité et le profil motivationnel dans lequel l'élève se préoccupe à la fois de ses performances et du contenu du ses apprentissages.
Historic Preservation and Residential Property Values: An Analysis of Texas Cities
Authors: Leichenko Robin M. , Coulson N. Edward , Listokin David
Published: July 2002

Designation of historic districts is increasingly used as a tool to revive or halt the deterioration of central-city neighbourhoods. While historic designation is generally thought to have a positive impact on property values, evidence on this issue is mixed. One limitation of previous research is that it typically focuses on historic neighbourhoods in one city and thus bases its conclusions on a very limited sample. This study expands upon previous work by examining the effects of designation on property values across a larger set of cities. The study employs hedonic regression models to estimate housing prices in historic districts and comparable neighbourhoods in nine Texas cities. Results suggest that, in most cases, historic designation is associated with higher property values.
Testing for the Existence of Office Sub-markets: A Comparison of Evidence from Two Cities
Authors: Dunse Neil , Leishman Chris , Watkins Craig
Published: July 2002

Most conceptual and applied economic models of the structure of urban office markets have been developed from traditional location theory. In their basic form, these models tend to posit a trade-off between accessibility and space. In the light of changing business practices and decentralisation, however, some authors have noted that the influence of agglomeration economies on the locational dynamics of commercial property markets may be declining. In this paper, we seek to undertake an indirect test of the power of intraurban office location theory. The paper is developed in two stages. In the first part, we examine the theoretical case for the existence of sub-markets in urban office markets and outline the implications of sub-market existence for traditional office location theory. In the second part of the paper, using data from Edinburgh and Glasgow, we undertake empirical tests for sub-market existence. A comparison of the results from the two city markets provides limited evidence of the existence of spatial sub-markets and suggests that markets might take different spatial forms depending on the urban context. The paper concludes by highlighting the need to account for the complex structure of urban property markets in developing models for property appraisal, taxation and land use planning purposes.
Unravelling the Process of 'Partnership' in Urban Regeneration Policy
Authors: Hastings Annette
Published: July 2002

In the UK, there is a political consensus that a multi-sectoral partnership approach is essential to achieve urban regeneration. As a term, however, 'partnership' is overused, ambiguous and politicised. The Conservative government has inscribed 'partnership' with a complex political agenda. It is not clear whether the politics of partnership are still dominated by a Thatcherite agenda of privatising and centralising urban policy or whether a new, more democratic era has been entered. The paper explores how the stakeholders in the central government-led Scottish Urban Partnerships conceive of the nature of their interrelationships within this political context. It also presents a conceptualisation of partnership processes which extends and refines the framework put forward by Mackintosh (1992). The paper concludes that the Urban Partnerships are essentially limited applications of the potential of the partnership approach.
Competition and Area Selection in Scotland's New Urban Policy
Authors: Turok Ivan , Hopkins Nick
Published: July 2002

Competition has become increasingly important as a method of allocating resources in urban policy, particularly with the shift towards decentralised, area-based strategies. This has created uncertainty about the rules of the game and aroused suspicions of arbitrary manipulation of area selection. In this paper, we investigate how area regeneration bids are assessed. We examine the reshaping of the Scottish Urban Programme under Programme for Partnership and the targeting of support on fewer priority areas. How were the successful areas chosen, and how fair and consistent were the procedures? We reveal discrepancies between the criteria put forward in the official guidelines and the outcome. Bid quality and social need seem to have been downplayed in relation to other considerations. The conclusion suggests how the policy might recover credibility and how government support for urban regeneration might be enhanced.
Kiss and Tell: ‘The Writing Cure’ in Kathryn Harrison's the Kiss (1997)
Authors: Hodgson-Blackburn Jacqueline
Published: July 2002

The article challenges conventional assumptions regarding the question of incest survival within contemporary discourses. A textual analysis of Kathryn Harrison's autobiographical novel tracing her consensual sexual relationship with her father is used to address the issue of failed or unresolved mourning as a prototypically ‘modern’ cultural phenomenon. Psychoanalytically informed feminist literary criticism is used to explore the parallels between the cultural construction of femininity and failed or postponed mourning in western historical and philosophical traditions. Following the work of Juliana Schiesari and Kathleen Woodward, the article contends that melancholia is a gendered discourse that has historically privileged male theorists and film-makers, such as Barthes and Fassbinder. The article suggests that contemporary women writers, such as Harrison, are engaged in a revisionary approach to the construction of loss within their writing. By situating themselves at the heart of the contemporary family narrative, instead of the ‘melancholic’ margins, they are able to produce a counter-discourse that dispels the conventional dynamics of the traditional family romance. By using the ‘writing cure’ to overcome ideological loss, the desiring daughter is able to challenge misogynist constructions of femininity within contemporary literature.
Modelling life satisfaction of Chinese adolescents in Hong Kong
Authors: Leung Jin-Pang , Zhang Li-Wei
Published: July 2002

The influence of self-concept and relationship on life satisfaction of adolescents was examined in 1099 Hong Kong Chinese junior high school children. Based on past research, it was hypothesised that self-concept and relationship are not independent of each other, and that they both have direct contribution toward the perception of life satisfaction in adolescents. Data were analysed using the structural equation modelling (SEM) technique. To test our hypotheses, we first proposed a structural model with self-concept and relationship as latent constructs and predictors of life satisfaction. The data collected were then fitted to the model by SEM. The results generally showed that the data fit the model well and that our hypotheses were confirmed. Specifically, it was demonstrated that the relationship construct exerts a greater influence on life satisfaction than the self-concept construct. For the relationship construct, parent-child relationship is much more important than school-child relationship. The resultant structural model therefore provides a concise summary of the existing data on life satisfaction of adolescents but its general application requires replication and validation in other cultural contexts.
How task demands influence time-based prospective memory performance in young and older adults
Authors: Martin Mike , Schumann-Hengsteler Ruth
Published: July 2002

Prospective memory performance as a measure of everyday cognitive functioning is of increasing importance for developmental research. However, comparisons of studies on prospective memory development in adults reveal essential differences. Although some studies report no age effects, others find age effects of widely varying magnitudes. We suggest that differences in these findings on prospective memory performance can be explained by an age by task interaction (i.e., large amounts of cognitive load imposed by time-based prospective memory tasks disproportionally penalise older adults who possess fewer cognitive resources). We explored our hypothesis in a study with 90 young adults (M = 24.0 years) and 75 older adults (M = 69.0 years) by manipulating the overall cognitive processing demands of the prospective task situation. We varied the cognitive load of the background task while holding constant the time-based prospective memory task. Results indicate that the effects of increased overall processing demands strongly influence older adults’ performance. Results are discussed within the framework of capacity explanations of cognitive ageing that focus on the role of working memory resources in monitoring processes.
The accumulation of problems of social functioning as a long-term process: Women and men compared
Authors: Rönkä Anna , Kinnunen Ulla , Pulkkinen Lea
Published: July 2002

Structural equation modelling was used to analyse the developmental processes involved in the accumulation of problems of social functioning from age 8 to age 36 in men ( n = 152) and women ( n = 145). The accumulation of risk factors in childhood and adolescence, including low control of emotions (aggressiveness and anxiety), school problems (poor adjustment, success, and motivation), and problems in the family (parental drinking and low socioeconomic status), predicted career instability, early timing of parenthood, and a sense of failure at age 27 in both sexes. Similarly, the accumulation of problems of social functioning (e.g. poor financial standing, poor intimate relationships, and drinking problems) tended to continue from age 27 to 36, and be reciprocally associated with career instability at a corresponding age in both men and women. Risk factors in childhood and adolescence directly explained the accumulation of problems of social functioning at age 27 only in men. For women, the relationship was indirect: Asense of failure and the early timing of motherhood mediated risk factors to problems of social functioning at age 36.
Preschoolers at play: Co-socialisers of emotional and social competence
Authors: Denham Susanne , Mason Teresa , Caverly Sarah , Schmidt Michelle , Hackney Rene , Caswell Cameron , DeMulder Elizabeth
Published: July 2002

Emotional competence is a contributor to young children’s social success. This study focused on these contributions from a relational perspective. The emotional expressions, and reactions to others’ emotional expressions, of 145 predominately Caucasian/middle income 3- and 4-year-olds were observed in their classrooms during unstructured play. Participants’ and playmates’ emotions and emotional responsiveness were classified into positive and negative playgroup types. Participants’ social competence was measured using peers, teachers, and parents as informants. Results indicate that preschoolers in playgroups characterised by anger and negative emotional responsiveness are evaluated as lacking in social competence up to a year later. Additionally, security of attachment and externalising temperament predicted membership in such playgroups. These effects held true more often for boys.