bluuebunny/crossref_metadata_2025 huggingface dataset:
Discoidin domain receptor 2 mediates the collagen II‐dependent release of interleukin‐6 in primary human chondrocytes
Authors: Klatt Andreas R , Zech Dagmar , Kühn Gertrud , Paul‐Klausch Brigitte , Klinger Gabriele , Renno Joerg H , Schmidt Joachim , Malchau Gebhart , Wielckens Klaus
Published: January 2009

We deciphered constituent parts of a signal transduction cascade that is initiated by collagen II and results in the release of various pro‐inflammatory cytokines, including interleukin‐6 (IL‐6), in primary human chondrocytes. This cascade represents a feed‐forward mechanism whereby cartilage matrix degradation is exacerbated by the mutually inducing effect of released collagen II fragments and pro‐inflammatory cytokines. We previously proposed discoidin domain receptor 2 as a central mediator in this event. Since this cascade plays a prominent role in the pathogenesis of osteoarthritis, our study further investigates the hypothesis that discoidin domain receptor 2 is a candidate receptor for collagen II, and that transcription factor NFκB, lipid kinase PI3K, and the MAP kinases are constituent parts of this very signal transduction cascade. To accomplish this, we selectively knocked down the molecules of interest in primary human chondrocytes, induced the specified cascade by incubating primary human chondrocytes with collagen II, and observed the outcome, specifically the changes in interleukin‐6 release. Knockdown was performed by siRNA‐mediated gene silencing in the case of discoidin domain receptor 2 (DDR2) or by using specific inhibitors for the remainder of the molecules. Results indicated that discoidin domain receptor 2 mediates the collagen II‐dependent release of interleukin‐6 in primary human chondrocytes and that MAP kinases p38, JNK and ERK, as well as transcription factor NFκB, are integral components of intracellular collagen II signalling. Given the detrimental role of these molecules in osteoarthritis, our findings provide new targets for more specific therapeutics, which may have fewer side effects than those currently applied. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Temporary and disadvantaged? The economic and spatial assimilation of New Zealand Maori in Sydney
Authors: Forrest James , Poulsen Michael , Johnston Ron
Published: January 2009

Much of the work on the spatial assimilation and, more recently, segmented (uneven) assimilation of ethnic group immigrants looks at ‘permanent’ settlement. Less attention has been paid to the settlement outcomes of unrestricted migration flows among linked national labour markets involving circulatory migration. Focusing on the occupational characteristics and settlement patterns of New Zealand Maori in Sydney, in a context where the labour markets of New Zealand and Australia are largely integrated, this study analyses the special characteristics of resultant intergenerational occupational characteristics and settlement patterns. Results are consistent with other studies portraying most New Zealand Maori as part of a return migration stream in the Australian context, with the majority only temporarily resident in Sydney. Maori in Sydney do not form major ethnic residential enclaves as they do in New Zealand cities, but rather the majority live in areas where the ‘host’ society is dominant but with a minority ethnic component. Thus most are not clustered in local enclaves, but socioeconomic disadvantage is a characteristic of those who are. Copyright © 2009 John Wiley & Sons, Ltd.
Crosslinking Metal Nanoparticles into the Polymer Backbone of Hydrogels Enables Preparation of Soft, Magnetic Field‐Driven Actuators with Muscle‐Like Flexibility
Authors: Fuhrer Roland , Athanassiou Evagelos Kimon , Luechinger Norman Albert , Stark Wendelin Jan
Published: January 2009

The combination of force and flexibility is at the core of biomechanics and enables virtually all body movements in living organisms. In sharp contrast, presently used machines are based on rigid, linear (cylinders) or circular (rotator in an electrical engine) geometries. As a potential bioinspired alternative, magnetic elastomers can be realized through dispersion of micro‐ or nanoparticles in polymer matrices and have attracted significant interest as soft actuators in artificial organs, implants, and devices for controlled drug delivery. At present, magnetic particle loss and limited actuator strength have restricted the use of such materials to niche applications. We describe the direct incorporation of metal nanoparticles into the backbone of a hydrogel and application as an ultra‐flexible, yet strong magnetic actuator. Covalent bonding of the particles prevents metal loss or leaching. Since metals have a far higher saturation magnetization and higher density than oxides, the resulting increased force/volume ratio afforded significantly stronger magnetic actuators with high mechanical stability, elasticity, and shape memory effect.
Effects of benfluorex–vitamin C supplementation on cutaneous capillaries of diabetic rats
Authors: Sarı Kılıçaslan Seda Mehtap , Özer Çiğdem
Published: January 2009

The ultrastructural changes on capillaries of the dermis in diabetic and benfluorex–vitamin C treated diabetic rats have been investigated. Three groups of 21 Wistar albino rats were used in the examination: control, diabetes, and benfluorex–vitamin C treated diabetic rats. Diabetes was induced by injection of streptozotocin. The streptozotocin‐induced group was treated for 21 days with vitamin C and benfluorex, of which antidiabetic and antihyperlipidemic effects were experimentally proved. Samples taken from the skin of rats' legs were examined under transmission electron microscopy. Swollen endothelial cells, narrowed capillary lumens, a thickened basement membrane, and fusion of mitochondrial cristae in the capillaries of diabetic rat dermis were seen. In the benfluorex–vitamin C treated group, contrary to the diabetic group, neither signs of degeneration in endothelial cells nor a significant difference with the control group with regard to capillary structure were observed. Amelioration in capillaries appears to be due to benfluorex and vitamin C treatment in diabetes.
Degradation of transglutaminase 2 by calcium‐mediated ubiquitination responding to high oxidative stress
Authors: Jeong Eui Man , Kim Chai-Wan , Cho Sung-Yup , Jang Gi-Yong , Shin Dong-Myung , Jeon Ju-Hong , Kim In-Gyu
Published: January 2009

MINT‐6824687: TG2 (uniprotkb:P21980) physically interacts (MI:0218) with Ubiquitin (uniprotkb:P62988) by anti bait coimmunoprecipitation (MI:0006)
Stoichiometry of molecular complexes at adhesions in living cells
Authors: Digman Michelle A. , Wiseman Paul W. , Choi Colin , Horwitz Alan R. , Gratton Enrico
Published: January 2009

We describe a method to detect molecular complexes and measure their stoichiometry in living cells from simultaneous fluctuations of the fluorescence intensity in two image channels, each detecting a different kind of protein. The number and brightness (N&B) analysis, namely, the use of the ratio between the variance and the average intensity to obtain the brightness of molecules, is extended to the cross-variance of the intensity fluctuations in two channels. We apply the cross-variance method to determine the stoichiometry of complexes containing paxillin and vinculin or focal adhesion kinase (FAK) in disassembling adhesions in mouse embryo fibroblasts expressing FAK, vinculin, and paxillin-tagged with EGFP and mCherry. We found no complexes of these proteins in the cytoplasm away from the adhesions. However, at the adhesions, large aggregates leave, forming a hole, during their disassembly. This hole shows cross-correlation between FAK and paxillin and vinculin and paxillin. From the amplitude of the correlated fluctuations we determine the composition of the aggregates leaving the adhesions. These aggregates disassemble rapidly in the cytoplasm because large complexes are found only in very close proximity to the adhesions or at their borders.
MicroRNAs as modulators of smoking-induced gene expression changes in human airway epithelium
Authors: Schembri Frank , Sridhar Sriram , Perdomo Catalina , Gustafson Adam M. , Zhang Xiaoling , Ergun Ayla , Lu Jining , Liu Gang , Zhang Xiaohui , Bowers Jessica , Vaziri Cyrus , Ott Kristen , Sensinger Kelly , Collins James J. , Brody Jerome S. , Getts Robert , Lenburg Marc E. , Spira Avrum
Published: January 2009

We have shown that smoking impacts bronchial airway gene expression and that heterogeneity in this response associates with smoking-related disease risk. In this study, we sought to determine whether microRNAs (miRNAs) play a role in regulating the airway gene expression response to smoking. We examined whole-genome miRNA and mRNA expression in bronchial airway epithelium from current and never smokers (n= 20) and found 28 miRNAs to be differentially expressed (P< 0.05) with the majority being down-regulated in smokers. We further identified a number of mRNAs whose expression level is highly inversely correlated with miRNA expression in vivo. Many of these mRNAs contain potential binding sites for the differentially expressed miRNAs in their 3′-untranslated region (UTR) and are themselves affected by smoking. We found that either increasing or decreasing the levels of mir-218 (a miRNA that is strongly affected by smoking) in both primary bronchial epithelial cells and H1299 cells was sufficient to cause a corresponding decrease or increase in the expression of predicted mir-218 mRNA targets, respectively. Further, mir-218 expression is reduced in primary bronchial epithelium exposed to cigarette smoke condensate (CSC), and alteration of mir-218 levels in these cells diminishes the induction of the predicted mir-218 target MAFG in response to CSC. These data indicate that mir-218 levels modulate the airway epithelial gene expression response to cigarette smoke and support a role for miRNAs in regulating host response to environmental toxins.
Duplicate genes increase expression diversity in closely related species and allopolyploids
Authors: Ha Misook , Kim Eun-Deok , Chen Z. Jeffrey
Published: January 2009

Polyploidy or whole genome duplication (WGD) provides raw genetic materials for sequence and expression evolution of duplicate genes. However, the mode and tempo of expression divergence between WGD duplicate genes in closely related species and recurrent allopolyploids are poorly understood.Arabidopsisis a suitable system for testing the hypothesis that duplicate genes increase expression diversity and regulatory networks. InArabidopsis, WGD occurred more than once before the split betweenArabidopsis thalianaandArabidopsis arenosa, and both natural and human-made allotetraploids are available. Comparative genomic hybridization analysis indicated that single-copy and duplicate genes after WGD were well preserved inA. thalianaandA. arenosa. Analysis of gene expression microarrays showed that duplicate genes generally had higher levels of expression divergence between two closely related species than single-copy genes. The proportion of the progenitors' duplicate genes that were nonadditively expressed in the resynthesized and natural allotetraploids was significantly higher than that of single-copy genes. Duplicate genes related to environmental stresses tended to be differentially expressed, and multicopy duplicate genes were likely to diverge expression between progenitors and in the allotetraploids. Compared with single-copy genes, duplicate genes tended to contain TATA boxes and less DNA methylation in the promoter regions, facilitating transcriptional regulation by binding transcription factors and/orcis-andtrans- acting proteins. The data suggest an important role of WGD duplicate genes in modulating diverse and novel gene expression changes in response to external environmental cues and internal genetic turmoil such as recurrent polyploidy events.
An unrecognized extracellular function for an intracellular adapter protein released from the cytoplasm into the tumor microenvironment
Authors: Mintz Paul J. , Cardó-Vila Marina , Ozawa Michael G. , Hajitou Amin , Rangel Roberto , Guzman-Rojas Liliana , Christianson Dawn R. , Arap Marco A. , Giordano Ricardo J. , Souza Glauco R. , Easley Jeffrey , Salameh Ahmad , Oliviero Salvatore , Brentani Ricardo R. , Koivunen Erkki , Arap Wadih , Pasqualini Renata
Published: January 2009

Mammalian cell membranes provide an interface between the intracellular and extracellular compartments. It is currently thought that cytoplasmic signaling adapter proteins play no functional role within the extracellular tumor environment. Here, by selecting combinatorial random peptide libraries in tumor-bearing mice, we uncovered a direct, specific, and functional interaction between CRKL, an adapter protein [with Src homology 2 (SH2)- and SH3-containing domains], and the plexin-semaphorin-integrin domain of β
1
integrin in the extracellular milieu. Through assays in vitro, in cellulo, and in vivo, we show that this unconventional and as yet unrecognized protein–protein interaction between a regulatory integrin domain (rather than a ligand-binding one) and an intracellular adapter (acting outside of the cells) triggers an alternative integrin-mediated cascade for cell growth and survival. Based on these data, here we propose that a secreted form of the SH3/SH2 adaptor protein CRKL may act as a growth-promoting factor driving tumorigenesis and may lead to the development of cancer therapeutics targeting secreted CRKL.
Behavioral experiments on biased voting in networks
Authors: Kearns Michael , Judd Stephen , Tan Jinsong , Wortman Jennifer
Published: January 2009

Many distributed collective decision-making processes must balance diverse individual preferences with a desire for collective unity. We report here on an extensive session of behavioral experiments on biased voting in networks of individuals. In each of 81 experiments, 36 human subjects arranged in a virtual network were financially motivated to reach global consensus to one of two opposing choices. No payments were made unless the entire population reached a unanimous decision within 1 min, but different subjects were paid more for consensus to one choice or the other, and subjects could view only the current choices of their network neighbors, thus creating tensions between private incentives and preferences, global unity, and network structure. Along with analyses of how collective and individual performance vary with network structure and incentives generally, we find that there are well-studied network topologies in which the minority preference consistently wins globally; that the presence of “extremist” individuals, or the awareness of opposing incentives, reliably improve collective performance; and that certain behavioral characteristics of individual subjects, such as “stubbornness,” are strongly correlated with earnings.
Monoamine oxidase A gene (MAOA) predicts behavioral aggression following provocation
Authors: McDermott Rose , Tingley Dustin , Cowden Jonathan , Frazzetto Giovanni , Johnson Dominic D. P.
Published: January 2009

Monoamine oxidase A gene (MAOA) has earned the nickname “warrior gene” because it has been linked to aggression in observational and survey-based studies. However, no controlled experimental studies have tested whether the warrior gene actually drives behavioral manifestations of these tendencies. We report an experiment, synthesizing work in psychology and behavioral economics, which demonstrates that aggression occurs with greater intensity and frequency as provocation is experimentally manipulated upwards, especially among low activity MAOA (MAOA-L) subjects. In this study, subjects paid to punish those they believed had taken money from them by administering varying amounts of unpleasantly hot (spicy) sauce to their opponent. There is some evidence of a main effect for genotype and some evidence for a gene by environment interaction, such that MAOA is less associated with the occurrence of aggression in a low provocation condition, but significantly predicts such behavior in a high provocation situation. This new evidence for genetic influences on aggression and punishment behavior complicates characterizations of humans as “altruistic” punishers and supports theories of cooperation that propose mixed strategies in the population. It also suggests important implications for the role of individual variance in genetic factors contributing to everyday behaviors and decisions.
Structure-based mechanism of lipoteichoic acid synthesis by
Staphylococcus aureus
LtaS
Authors: Lu Duo , Wörmann Mirka E. , Zhang Xiaodong , Schneewind Olaf , Gründling Angelika , Freemont Paul S.
Published: January 2009

Staphylococcus aureus
synthesizes polyglycerol-phosphate lipoteichoic acid (LTA) from phosphatidylglycerol. LtaS, a predicted membrane protein with 5 N-terminal transmembrane helices followed by a large extracellular part (eLtaS), is required for staphylococcal growth and LTA synthesis. Here, we report the first crystal structure of the eLtaS domain at 1.2-Å resolution and show that it assumes a sulfatase-like fold with an α/β core and a C-terminal part composed of 4 anti-parallel β-strands and a long α-helix. Overlaying eLtaS with sulfatase structures identified active site residues, which were confirmed by alanine substitution mutagenesis and in vivo enzyme function assays. The cocrystal structure with glycerol-phosphate and the coordination of a Mn
2+
cation allowed us to propose a reaction mechanism, whereby the active site threonine of LtaS functions as nucleophile for phosphatidylglycerol hydrolysis and formation of a covalent threonine–glycerolphosphate intermediate. These results will aid in the development of LtaS-specific inhibitors for
S. aureus
and many other Gram-positive pathogens.
Multiple transcription factor codes activate epidermal wound–response genes in
Drosophila
Authors: Pearson Joseph C. , Juarez Michelle T. , Kim Myungjin , Drivenes Øyvind , McGinnis William
Published: January 2009

Wounds in
Drosophila
and mouse embryos induce similar genetic pathways to repair epidermal barriers. However, the transcription factors that transduce wound signals to repair epidermal barriers are largely unknown. We characterize the transcriptional regulatory enhancers of 4 genes—
Ddc
,
ple
,
msn
, and
kkv
—that are rapidly activated in epidermal cells surrounding wounds in late
Drosophila
embryos and early larvae. These epidermal wound enhancers all contain evolutionarily conserved sequences matching binding sites for JUN/FOS and GRH transcription factors, but vary widely in
trans
- and
cis
-requirements for these inputs and their binding sites. We propose that the combination of GRH and FOS is part of an ancient wound–response pathway still used in vertebrates and invertebrates, but that other mechanisms have evolved that result in similar transcriptional output. A common, but largely untested assumption of bioinformatic analyses of gene regulatory networks is that transcription units activated in the same spatial and temporal patterns will require the same
cis
-regulatory codes. Our results indicate that this is an overly simplistic view.
Vacuolar transport of nicotine is mediated by a multidrug and toxic compound extrusion (MATE) transporter in
Nicotiana tabacum
Authors: Morita Masahiko , Shitan Nobukazu , Sawada Keisuke , Van Montagu Marc C. E. , Inzé Dirk , Rischer Heiko , Goossens Alain , Oksman-Caldentey Kirsi-Marja , Moriyama Yoshinori , Yazaki Kazufumi
Published: January 2009

Alkaloids play a key role in plant defense mechanisms against pathogens and herbivores, but the plants themselves need to cope with their toxicity as well. The major alkaloid of the
Nicotiana
species, nicotine, is translocated via xylem transport from the root tissues where it is biosynthesized to the accumulation sites, the vacuoles of leaves. To unravel the molecular mechanisms behind this membrane transport, we characterized one transporter, the tobacco (
Nicotiana tabacum
) jasmonate-inducible alkaloid transporter 1 (Nt-JAT1), whose expression was coregulated with that of nicotine biosynthetic genes in methyl jasmonate-treated tobacco cells. Nt-JAT1, belonging to the family of multidrug and toxic compound extrusion transporters, was expressed in roots, stems, and leaves, and localized in the tonoplast of leaf cells. When produced in yeast cells, Nt-JAT1 occurred mainly in the plasma membrane and showed nicotine efflux activity. Biochemical analysis with proteoliposomes reconstituted with purified Nt-JAT1 and bacterial F
0
F
1
-ATPase revealed that Nt-JAT1 functioned as a proton antiporter and recognized endogenous tobacco alkaloids, such as nicotine and anabasine, and other alkaloids, such as hyoscyamine and berberine, but not flavonoids. These findings strongly suggest that Nt-JAT1 plays an important role in the nicotine translocation by acting as a secondary transporter responsible for unloading of alkaloids in the aerial parts and deposition in the vacuoles.
RETRACTED: Anthracycline chemotherapy inhibits HIF-1 transcriptional activity and tumor-induced mobilization of circulating angiogenic cells
Authors: Lee KangAe , Qian David Z. , Rey Sergio , Wei Hong , Liu Jun O. , Semenza Gregg L.
Published: January 2009

Using a cell-based reporter gene assay, we screened a library of drugs in clinical use and identified the anthracycline chemotherapeutic agents doxorubicin and daunorubicin as potent inhibitors of hypoxia-inducible factor 1 (HIF-1)-mediated gene transcription. These drugs inhibited HIF-1 by blocking its binding to DNA. Daily administration of doxorubicin or daunorubicin potently inhibited the transcription of a HIF-1-dependent reporter gene as well as endogenous HIF-1 target genes encoding vascular endothelial growth factor, stromal-derived factor 1, and stem cell factor in tumor xenografts. CXCR4
+
/sca1
+
, VEGFR2
+
/CD34
+
, and VEGFR2
+
/CD117
+
bone-marrow derived cells were increased in the peripheral blood of SCID mice bearing prostate cancer xenografts but not in tumor-bearing mice treated for 5 days with doxorubicin or daunorubicin, which dramatically reduced tumor vascularization. These results provide a molecular basis for the antiangiogenic effect of anthracycline therapy and have important implications for refining the use of these drugs to treat human cancer more effectively.
Molecular and Functional Characterization of PEBP Genes in Barley Reveal the Diversification of Their Roles in Flowering
Authors: Kikuchi Rie , Kawahigashi Hiroyuki , Ando Tsuyu , Tonooka Takuji , Handa Hirokazu
Published: January 2009

Five barley (Hordeum vulgare) PEBP (for phosphatidylethanolamine-binding protein) genes were analyzed to clarify their functional roles in flowering using transgenic, expression, and quantitative trait locus analyses. Introduction of HvTFL1 and HvMFT1 into rice (Oryza sativa) plants did not result in any changes in flowering, suggesting that these two genes have functions distinct from flowering. Overexpression of HvFT1, HvFT2, and HvFT3 in rice resulted in early heading, indicating that these FT-like genes can act as promoters of the floral transition. HvFT1 transgenic plants showed the most robust flowering initiation. In barley, HvFT1 was expressed at the time of shoot meristem phase transition. These results suggest that HvFT1 is the key gene responsible for flowering in the barley FT-like gene family. HvFT2 transgenic plants also showed robust flowering initiation, but HvFT2 was expressed only under short-day (SD) conditions during the phase transition, suggesting that its role is limited to specific photoperiodic conditions in barley. Flowering activity in HvFT3 transgenic rice was not as strong and was modulated by the photoperiod. These results suggest that HvFT3 functions in flowering promotion but that its effect is indirect. HvFT3 expression was observed in Morex, a barley cultivar carrying a dominant allele of Ppd-H2, a major quantitative trait locus for flowering under SD conditions, although no expression was detected in Steptoe, a cultivar carrying ppd-H2. HvFT3 was expressed in Morex under both long-day and SD conditions, although its expression was increased under SD conditions. HvFT3 was mapped to chromosome 1HL, the same chromosome that carries Ppd-H2. Genomic sequence analyses revealed that Morex possesses an intact HvFT3 gene, whereas most of this gene has been lost in Steptoe. These data strongly suggest that HvFT3 may be identical to Ppd-H2.
Positive Fluorescent Selection Permits Precise, Rapid, and In-Depth Overexpression Analysis in Plant Protoplasts
Authors: Bargmann Bastiaan O.R. , Birnbaum Kenneth D.
Published: January 2009

Transient genetic modification of plant protoplasts is a straightforward and rapid technique for the study of numerous aspects of plant biology. Recent studies in metazoan systems have utilized cell-based assays to interrogate signal transduction pathways using high-throughput methods. Plant biologists could benefit from new tools that expand the use of cell culture for large-scale analysis of gene function. We have developed a system that employs fluorescent positive selection in combination with flow cytometric analysis and fluorescence-activated cell sorting to isolate responses in the transformed protoplasts exclusively. The system overcomes the drawback that transfected protoplast suspensions are often a heterogeneous mix of cells that have and have not been successfully transformed. This Gateway-compatible system enables high-throughput screening of genetic circuitry using overexpression. The incorporation of a red fluorescent protein selection marker enables combined utilization with widely available green fluorescent protein (GFP) tools. For instance, such a dual labeling approach allows cytometric analysis of GFP reporter gene activation expressly in the transformed cells or fluorescence-activated cell sorting-mediated isolation and downstream examination of overexpression effects in a specific GFP-marked cell population. Here, as an example, novel uses of this system are applied to the study of auxin signaling, exploiting the red fluorescent protein/GFP dual labeling capability. In response to manipulation of the auxin response network through overexpression of dominant negative auxin signaling components, we quantify effects on auxin-responsive DR5∷GFP reporter gene activation as well as profile genome-wide transcriptional changes specifically in cells expressing a root epidermal marker.
Diel Growth Cycle of Isolated Leaf Discs Analyzed with a Novel, High-Throughput Three-Dimensional Imaging Method Is Identical to That of Intact Leaves
Authors: Biskup Bernhard , Scharr Hanno , Fischbach Andreas , Wiese-Klinkenberg Anika , Schurr Ulrich , Walter Achim
Published: January 2009

Dicot leaves grow with pronounced diel (24-h) cycles that are controlled by a complex network of factors. It is an open question to what extent leaf growth dynamics are controlled by long-range or by local signals. To address this question, we established a stereoscopic imaging system, GROWSCREEN 3D, which quantifies surface growth of isolated leaf discs floating on nutrient solution in wells of microtiter plates. A total of 458 leaf discs of tobacco (Nicotiana tabacum) were cut at different developmental stages, incubated, and analyzed for their relative growth rates. The camera system was automatically displaced across the array of leaf discs; visualization and camera displacement took about 12 s for each leaf disc, resulting in a time interval of 1.5 h for consecutive size analyses. Leaf discs showed a comparable diel leaf growth cycle as intact leaves but weaker peak growth activity. Hence, it can be concluded that the timing of leaf growth is regulated by local rather than by systemic control processes. This conclusion was supported by results from leaf discs of Arabidopsis (Arabidopsis thaliana) Landsberg erecta wild-type plants and starch-free1 mutants. At night, utilization of transitory starch leads to increased growth of Landsberg erecta wild-type discs compared with starch-free1 discs. Moreover, the decrease of leaf disc growth when exposed to different concentrations of glyphosate showed an immediate dose-dependent response. Our results demonstrate that a dynamic leaf disc growth analysis as we present it here is a promising approach to uncover the effects of internal and external cues on dicot leaf development.
Proteins from Multiple Metabolic Pathways Associate with Starch Biosynthetic Enzymes in High Molecular Weight Complexes: A Model for Regulation of Carbon Allocation in Maize Amyloplasts
Authors: Hennen-Bierwagen Tracie A. , Lin Qiaohui , Grimaud Florent , Planchot Véronique , Keeling Peter L. , James Martha G. , Myers Alan M.
Published: January 2009

Starch biosynthetic enzymes from maize (Zea mays) and wheat (Triticum aestivum) amyloplasts exist in cell extracts in high molecular weight complexes; however, the nature of those assemblies remains to be defined. This study tested the interdependence of the maize enzymes starch synthase IIa (SSIIa), SSIII, starch branching enzyme IIb (SBEIIb), and SBEIIa for assembly into multisubunit complexes. Mutations that eliminated any one of those proteins also prevented the others from assembling into a high molecular mass form of approximately 670 kD, so that SSIII, SSIIa, SBEIIa, and SBEIIb most likely all exist together in the same complex. SSIIa, SBEIIb, and SBEIIa, but not SSIII, were also interdependent for assembly into a complex of approximately 300 kD. SSIII, SSIIa, SBEIIa, and SBEIIb copurified through successive chromatography steps, and SBEIIa, SBEIIb, and SSIIa coimmunoprecipitated with SSIII in a phosphorylation-dependent manner. SBEIIa and SBEIIb also were retained on an affinity column bearing a specific conserved fragment of SSIII located outside of the SS catalytic domain. Additional proteins that copurified with SSIII in multiple biochemical methods included the two known isoforms of pyruvate orthophosphate dikinase (PPDK), large and small subunits of ADP-glucose pyrophosphorylase, and the sucrose synthase isoform SUS-SH1. PPDK and SUS-SH1 required SSIII, SSIIa, SBEIIa, and SBEIIb for assembly into the 670-kD complex. These complexes may function in global regulation of carbon partitioning between metabolic pathways in developing seeds.
discordia1 and alternative discordia1 Function Redundantly at the Cortical Division Site to Promote Preprophase Band Formation and Orient Division Planes in Maize
Authors: Wright Amanda J. , Gallagher Kimberly , Smith Laurie G.
Published: January 2009

In plants, cell wall placement during cytokinesis is determined by the position of the preprophase band (PPB) and the subsequent expansion of the phragmoplast, which deposits the new cell wall, to the cortical division site delineated by the PPB. New cell walls are often incorrectly oriented during asymmetric cell divisions in the leaf epidermis of maize (Zea mays) discordia1 (dcd1) mutants, and this defect is associated with aberrant PPB formation in asymmetrically dividing cells. dcd1 was cloned and encodes a putative B'' regulatory subunit of the PP2A phosphatase complex highly similar to Arabidopsis thaliana FASS/TONNEAU2, which is required for PPB formation. We also identified alternative discordia1 (add1), a second gene in maize nearly identical to dcd1. While loss of add1 function does not produce a noticeable phenotype, knock down of both genes in add1(RNAi) dcd1(RNAi) plants prevents PPB formation and causes misorientation of symmetric and asymmetric cell divisions. Immunolocalization studies with an antibody that recognizes both DCD1 and ADD1 showed that these proteins colocalize with PPBs and remain at the cortical division site through metaphase. Our results indicate that DCD1 and ADD1 function in PPB formation, that this function is more critical in asymmetrically dividing cells than in symmetrically dividing cells, and that DCD1/ADD1 may have other roles in addition to promoting PPB formation at the cortical division site.
A Novel Polyamine Acyltransferase Responsible for the Accumulation of Spermidine Conjugates in Arabidopsis Seed
Authors: Luo Jie , Fuell Christine , Parr Adrian , Hill Lionel , Bailey Paul , Elliott Katherine , Fairhurst Shirley A. , Martin Cathie , Michael Anthony J.
Published: January 2009

Hydroxycinnamic acid amides are a class of secondary metabolites distributed widely in plants. We have identified two sinapoyl spermidine derivatives, N-((4′-O-glycosyl)-sinapoyl),N′-sinapoylspermidine and N,N′-disinapoylspermidine, which comprise the two major polyamine conjugates that accumulate in Arabidopsis thaliana seed. Using metabolic profiling of knockout mutants to elucidate the functions of members of the BAHD acyltransferase family in Arabidopsis, we have also identified two genes encoding spermidine disinapoyl transferase (SDT) and spermidine dicoumaroyl transferase (SCT) activities. At2g23510, which is expressed mainly in seeds, encodes a spermidine sinapoyl CoA acyltransferase (SDT) that is required for the production of disinapoyl spermidine and its glucoside in Arabidopsis seed. The structurally related BAHD enzyme encoded by At2g25150 is expressed specifically in roots and has spermidine coumaroyl CoA acyltransferase (SCT) activity both in vitro and in vivo.
ARABIDOPSIS DEHISCENCE ZONE POLYGALACTURONASE1 (ADPG1), ADPG2, and QUARTET2 Are Polygalacturonases Required for Cell Separation during Reproductive Development inArabidopsis
Authors: Ogawa Mikihiro , Kay Pippa , Wilson Sarah , Swain Stephen M.
Published: January 2009

Cell separation is thought to involve degradation of pectin by several hydrolytic enzymes, particularly polygalacturonase (PG). Here, we characterize an activation tagging line with reduced growth and male sterility caused by increased expression of a PG encoded by QUARTET2 (QRT2). QRT2 is essential for pollen grain separation and is part of a small family of three closely related endo-PGs in the Arabidopsis thaliana proteome, including ARABIDOPSIS DEHISCENCE ZONE POLYGALACTURONASE1 (ADPG1) and ADPG2. Functional assays and complementation experiments confirm that ADPG1, ADPG2, and QRT2 are PGs. Genetic analysis demonstrates that ADPG1 and ADPG2 are essential for silique dehiscence. In addition, ADPG2 and QRT2 contribute to floral organ abscission, while all three genes contribute to anther dehiscence. Expression analysis is consistent with the observed mutant phenotypes. INDEHISCENT (IND) encodes a putative basic helix-loop-helix required for silique dehiscence, and we demonstrate that the closely related HECATE3 (HEC3) gene is required for normal seed abscission and show that IND and HEC3 are required for normal expression of ADPG1 in the silique dehiscence zone and seed abscission zone, respectively. We also show that jasmonic acid and ethylene act together with abscisic acid to regulate floral organ abscission, in part by promoting QRT2 expression. These results demonstrate that multiple cell separation events, including both abscission and dehiscence, require closely related PG genes.
Telling a true story or making it up: Discourse on the effectiveness of the bookshop model for public libraries
Authors: McMenemy David
Published: January 2009

Purpose

The purpose of this paper is to examine the often cited example of the book retailer, and other commercial imperatives, as adequate models for implementation in the public library.

Design/methodology/approach

The paper provides a critical reflection on some of the pertinent issues.

Findings

The paper finds that we should consider models in their entirety and not on the basis of superficial improvements to layout and design. The adoption of a commercial model within the public realm poses as many dangers as it does advantages.

Practical implication

The paper should be of interest to anyone working in public libraries, or those considering some of the issues related to the commercialisation of the public sector, especially public libraries.

Originality/value

The paper offers an original thought piece on the influence of the private sector on the public library service in the UK, and the potential this has to alter the ethos of the service.
Managing the implementation of a federated search tool in an academic library
Authors: Joint Nicholas
Published: January 2009

Purpose

The purpose of this paper is to look at some of the broader design and management issues that occur during the implementation of a federated search tool in a modern academic library, and tries to tease out some of the background concepts that librarians should consider.

Design/methodology/approach

An overview of the main advantages and disadvantages of federated search tools in comparison with existing library tools and internet search engines such as Google.

Findings

A successful implementation of a federated search engine was found to depend on a radical approach which subordinates other existing library search tools to the new one‐stop search engine. This new search interface must in turn be designed for simplicity, and not to mimic existing, overly complex library information retrieval devices.

Research limitations/implications

The emphasis is on the softer, general aspects of managing search tool implementation, rather than the hard, technical side. So, this paper may be best read in tandem with a specific description of a search tool implementation, which describes some of the technical “back office” aspects of federated search. Research developments in these technical areas may well soon lead to the elimination of some of the negative aspects which this paper presents to the non‐technical library manager simply as a “given”.

Practical implications

This paper outlines many of the practical challenges in search tool implementation which librarians might otherwise not anticipate.

Originality/value

The approach in this investigation is to present the broader implications of search tool implementation in a way that is stripped of technical complexity, in order to show the larger management issues as clearly as possible.
Students’ attitudes towards e‐books in a Scottish Higher Education Institute
Authors: Abdullah Noorhidawati , Gibb Forbes
Published: January 2009

Purpose

The purpose of this paper is to present the third of three inter‐related experiments investigating the use and usability of e‐books in Higher Education based on experiments conducted at the University of Strathclyde. This study has looked in greater detail at user interactions with e‐books for reference purposes by focusing on searching and browsing tasks using three search tools: back‐of the‐book index (BoBI), table of contents (ToC) and full text search (FTS).

Design/methodology/approach

This study was carried out by subject‐specific users and using a between‐subjects approach. The target population was MSc and research students in the Department of Computer and Information Sciences, at the University of Strathclyde and involved a total of 45 responses.

Findings

The study found that a BoBI was more efficient compared to a ToC and FTS tool for finding information in an e‐book environment. A BoBI was found to perform the best for accurately finding relevant content in e‐books. The usability evaluation also found that a BoBI was more useful compared to a ToC for finding information in an e‐book environment.

Research limitations/implications

The study was focused only on the usability of e‐books, and in particular on retrieval performance, user satisfaction and preferences regarding BoBI, ToC and FTS, and not on other features such as the user interface. The e‐book usability evaluation was constrained in so far as the e‐books used were: non‐fiction; in the domain of information retrieval; e‐books that already had BoBIs with hyperlinks from the BoBI to the text; e‐books that had ToCs with hyperlinks; e‐books that had FTS tools; and e‐books that were available in PDF format.

Practical implications

The study is important in gaining a better understanding of the retrieval performance of three search tools (BoBI, ToC and FTS) for browsing for relevant, and searching for specific, information in e‐books. This will be of value for designing better e‐books and access systems.

Originality/value

The strengths and novelty of this study are the methodology that was used, the comprehensive inter‐comparison of tools, and the size of the population. The findings have supported empirically – through an assessment of the performances of BoBIs and ToCs – the need for an enhanced library catalogue system in order to improve users’ browsing and searching capabilities for relevant book content.
Mind thegap
Authors: Singh Rajesh
Published: January 2009

Purpose

Why are some libraries more market‐oriented than others? The purpose of this paper is to answer this question by examining the pertinent issues underlying the inter‐relationship between market‐orientation and superior service performance.

Design/methodology/approach

An integrated methodological approach of qualitative as well as quantitative methods was used to gain knowledge behind the market‐orientation – service performance relationship. The directors and consumers of 33 academic and special libraries participated as respondents in this study.

Findings

In total, three kinds of libraries were found: the strong; the medium; and the weak. The findings show that the higher market‐orientation is positively connected with the libraries’ superior service performance.

Research limitations/implications

The implication of this research does suggest that thegapbetween the service provider and receiver can be closed by increasing the marketing competence of service provider.

Practical implications

The practical implication for libraries is that it pays to be market‐oriented, the ultimate result being higher customer satisfaction.

Originality/value

The relationship between market‐orientation and service performance has yet to be explored and established in the library world. This is one of the first such studies which attempted to investigate this inter‐relationship.
Whither reference services? Views of some Ghanaian library school students
Authors: Dadzie Perpetua S.
Published: January 2009

Purpose

The purpose of this paper is to report on the experiences of 65 five library students who visited one of three selected libraries on the campus of the University of Ghana to find out the extent to which the principles of reference services were being adhered to.

Design/methodology/approach

The unobstrusive method for evaluating reference services was used. Students were specifically asked to pose two questions (specific‐search or research questions) of their choice to two different library staff at the reference desk of the selected library (The library staff were unaware of this evaluation and exhibited their real behaviors to the clients.). The choice of these types of questions was to allow the library staff to engage them in a reference interview. Their observations were to be summarized in a two page report.

Findings

Students were not only concerned with correct answers to their questions, but were influenced to return to the same library staff by certain factors such as approachability of the library staff, effective assessment of their information need, good communication skills and the attentiveness of the library staff.

Practical implications

This exercise gave students a first‐hand experience of being information seekers and directly experiencing what ordinary users are subjected to whenever they visited libraries. This experience it is hoped would guide them when they are later employed in libraries to conform to behaviors that enhance the quality of reference interview and user satisfaction.

Originality/value

This is a modest contribution to the literature on reference services from a developing country's perspective as very few empirical studies are carried out in this area.
Thermohydrostatic analysis of capillary compensated symmetric hole‐entry hybrid journal bearing operating with non‐Newtonian lubricant
Authors: Garg H.C. , Kumar Vijay , Sharda H.B.
Published: January 2009

Purpose

Every high speed machine, demanding high level of perfection, can operate successfully through a precise design of bearings. Such a design can be formulated after carefully studying both static and dynamic characteristics of the journal bearing. The present paper aims to describe the study of static and dynamic performance of a hole‐entry hybrid journal bearing system compensated with capillary restrictor by considering the combined influence of thermal effects and non‐Newtonian behavior of the lubricant.

Design/methodology/approach

The variation of the viscosity due to the non‐Newtonian behavior of the lubricant and temperature rise is considered in the study. The numerical solution of the generalized Reynold's, equation governing the flow of the lubricant having variable viscosity along with the energy and heat conduction equations is obtained using finite element method. The non‐Newtonian lubricant has been assumed to follow the cubic shear stress law. The study includes performance of a double row symmetric hole entry hybrid journal bearing configuration containing 12 holes per row.

Findings

The results indicate that change in viscosity of lubricant affects the bearing design parameters.

Originality/value

The paper shows that accurate theoretical modeling of the bearing is an effective tool for the selection of design parameter such as bearing land width ratio (ab), restrictor design parameter (Cs2), and non‐linearity factor (K).
Research on solid film lubricant and its failure for seeker valve
Authors: Xiao Jun , Chen Jian‐min , Zhou Hui‐di , Huang Pei
Published: January 2009

Purpose

The seeker value is a crucial part of a navigation system, able to adjust the nitrogen airflow of the system so as to manipulate guiding and tailing movement. The paper aims to determine the causes of failure of the valve system.

Design/methodology/approach

In order to reduce friction and ensure the smooth operation of the valve, a new MoS2 solid film lubricant cured at room temperature, was coated on the plunger surface of the valve. SEM, EDS, and FTIR analysis was conducted.

Findings

Through analysis it was found that the lock failure of the valves was caused by the absence of MoS2 in the surface and softening and melding of the film at an extended electrifying.

Originality/value

The paper outlines the strategies to avoid lock failure – by improving the quality of the solid film lubricant and modifying the assembly process of the valve.
Tribological investigation of MPTS‐MPTES SAMs
Authors: Cheng Xianhua
Published: January 2009

Purpose

This paper's aim is to study the tribological properties of hyrid monolayer composited by γ‐mercapto‐propyl trimethoxysilane (MPTS) and γ‐methacryloxy propyltrimethoxysilane (MPTES), and estimated the action mechanism.

Design/methodology/approach

MPTS‐MPTES were self‐assembled on a hydroxylated silicon substrate to form a two‐dimensional hybrid monolayer. Atomic force microscope (AFM), X‐ray photoelectron spectrometry and contact angle measurement were used to characterize the MPTS‐MPTES hybrid self‐assembled monolayer (SAM). The macrofriction and wear behaviors of the film sliding against an AISI‐52100 steel ball were examined on a unidirectional friction and wear tester, and the worn surface morphologies were observed on an AFM.

Findings

The tribological results show that the friction coefficient of silicon substrate reduces from 0.86 to 0.18 after the formation of the MPTS‐MPTES hybrid SAM on its surface, and the thin film has a long wear life (2,620 sliding pass). It is demonstrated that the MPTS‐MPTES SAM exhibited good wear resistant property with a low friction coefficient, and the superior friction reduction and wear life were attributed to the low surface energy and the characteristics of the hybrid SAM.

Research limitations/implications

The film's tribological performance under dynamic load is not estimated.

Practical implications

A hybrid monolayer with superior tribological property was synthesized on a silicon substrate by self‐assembly process, and maybe it is the potential solution for micro‐electromechanical‐system lubrication.

Originality/value

This paper provides a study way of hybrid SAM on a silicon substrate as lubricating coating.