bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Ubiquitin-Specific Protease Subfamily UBP3/UBP4 Is Essential for Pollen Development and Transmission in Arabidopsis
Authors: Doelling Jed H. , Phillips Allison R. , Soyler-Ogretim Gulsum , Wise Jasen , Chandler Jennifer , Callis Judy , Otegui Marisa S. , Vierstra Richard D. 
Published: September 2007

AbstractDeubiquitinating enzymes are essential to the ubiquitin (Ub)/26S proteasome system where they release Ub monomers from the primary translation products of poly-Ub and Ub extension genes, recycle Ubs from polyubiquitinated proteins, and reverse the effects of ubiquitination by releasing bound Ubs from individual targets. The Ub-specific proteases (UBPs) are one large family of deubiquitinating enzymes that bear signature cysteine and histidine motifs. Here, we genetically characterize a UBP subfamily in Arabidopsis (Arabidopsis thaliana) encoded by paralogous UBP3 and UBP4 genes. Whereas homozygous ubp3 and ubp4 single mutants do not display obvious phenotypic abnormalities, double-homozygous mutant individuals could not be created due to a defect in pollen development and/or transmission. This pollen defect was rescued with a transgene encoding wild-type UBP3 or UBP4, but not with a transgene encoding an active-site mutant of UBP3, indicating that deubiquitination activity of UBP3/UBP4 is required. Nuclear DNA staining revealed that ubp3 ubp4 pollen often fail to undergo mitosis II, which generates the two sperm cells needed for double fertilization. Substantial changes in vacuolar morphology were also evident in mutant grains at the time of pollen dehiscence, suggesting defects in vacuole and endomembrane organization. Even though some ubp3 ubp4 pollen could germinate in vitro, they failed to fertilize wild-type ovules even in the absence of competing wild-type pollen. These studies provide additional evidence that the Ub/26S proteasome system is important for male gametogenesis in plants and suggest that deubiquitination of one or more targets by UBP3/UBP4 is critical for the development of functional pollen.
Cytokinins in the Bryophyte Physcomitrella patens: Analyses of Activity, Distribution, and Cytokinin Oxidase/Dehydrogenase Overexpression Reveal the Role of Extracellular Cytokinins
Authors: von Schwartzenberg Klaus , Núñez Marta Fernández , Blaschke Hanna , Dobrev Petre I. , Novák Ondrej , Motyka Václav , Strnad Miroslav 
Published: September 2007

Abstract
Ultra-performance liquid chromatography-tandem mass spectrometry was used to establish the cytokinin profile of the bryophyte Physcomitrella patens (Hedw.) B.S.G.; of 40 analyzed cytokinins, 20 were detected. cis-Zeatin-riboside-O-glucoside, N 6-(Δ2-isopentenyl)adenosine-5′-monophosphate (iPRMP), and trans-zeatin-riboside-O-glucoside were the most abundant intracellular cytokinins. In addition, the aromatic cytokinins N 6-benzyladenosine (BAR), N 6-benzyladenine, meta-, and ortho-topolin were detected. Unexpectedly, the most abundant extracellular cytokinin was the nucleotide iPRMP, and its identity was confirmed by quadrupole time-of-flight mass spectrometry. The effects of overexpressing a heterologous cytokinin oxidase/dehydrogenase (CKX; EC 1.4.3.18/1.5.99.12) gene (AtCKX2 from Arabidopsis [Arabidopsis thaliana]) on the intracellular and extracellular distribution of cytokinins was assessed. In cultures of CKX-transformed plants, ultra-performance liquid chromatography-tandem mass spectrometry measurements showed that there were pronounced reductions in the extracellular concentrations of N 6-(Δ2-isopentenyl)adenine (iP) and N 6-(Δ2-isopentenyl)adenosine (iPR), but their intracellular cytokinin concentrations were only slightly affected. In vitro and in vivo measured CKX activity was shown to be strongly increased in the transformants. Major phenotypic changes observed in the CKX-overexpressing plants included reduced and retarded budding, absence of sexual reproduction, and abnormal protonema cells. In bud-induction bioassays with wild-type Physcomitrella, the nucleotides iPRMP, trans-zeatin-riboside-5′-monophosphate, BAR monophosphate, and the cis-zeatin forms cZ and cZR had no detectable effects, while the activities displayed by other selected cytokinins were in the following order: iP &gt; tZ &gt; N 6-benzyladenine &gt; BAR &gt; iPR &gt; tZR &gt; meta-topolin &gt; dihydrozeatin &gt; ortho-topolin. The results on wild type and CKX transgenics suggest that extracellular iP and iPR are the main cytokinins responsible for inducing buds in the bryophyte Physcomitrella. Cytokinin profile is discussed regarding the evolution of cytokinin biosynthetic pathways.
Hydrogen Peroxide Generation by the Pepper Extracellular Peroxidase CaPO2 Activates Local and Systemic Cell Death and Defense Response to Bacterial Pathogens
Authors: Choi Hyong Woo , Kim Young Jin , Lee Sung Chul , Hong Jeum Kyu , Hwang Byung Kook 
Published: September 2007

AbstractReactive oxygen species (ROS) are responsible for mediating cellular defense responses in plants. Controversy has existed over the origin of ROS in plant defense. We have isolated a novel extracellular peroxidase gene, CaPO2, from pepper (Capsicum annuum). Local or systemic expression of CaPO2 is induced in pepper by avirulent Xanthomonas campestris pv vesicatoria (Xcv) infection. We examined the function of the CaPO2 gene in plant defense using the virus-induced gene silencing technique and gain-of-function transgenic plants. CaPO2-silenced pepper plants were highly susceptible to Xcv infection. Virus-induced gene silencing of the CaPO2 gene also compromised hydrogen peroxide (H2O2) accumulation and hypersensitive cell death in leaves, both locally and systemically, during avirulent Xcv infection. In contrast, overexpression of CaPO2 in Arabidopsis (Arabidopsis thaliana) conferred enhanced disease resistance accompanied by cell death, H2O2 accumulation, and PR gene induction. In CaPO2-overexpression Arabidopsis leaves infected by Pseudomonas syringae pv tomato, H2O2 generation was sensitive to potassium cyanide (a peroxidase inhibitor) but insensitive to diphenylene iodonium (an NADPH oxidase inhibitor), suggesting that H2O2 generation depends on peroxidase in Arabidopsis. Together, these results indicate that the CaPO2 peroxidase is involved in ROS generation, both locally and systemically, to activate cell death and PR gene induction during the defense response to pathogen invasion.
Fluorescent Reporter Proteins for the Tonoplast and the Vacuolar Lumen Identify a Single Vacuolar Compartment in Arabidopsis Cells
Authors: Hunter Paul R. , Craddock Christian P. , Di Benedetto Sara , Roberts Lynne M. , Frigerio Lorenzo 
Published: September 2007

Abstract
We generated fusions between three Arabidopsis (Arabidopsis thaliana) tonoplast intrinsic proteins (TIPs; α-, γ-, and δ-TIP) and yellow fluorescent protein (YFP). We also produced soluble reporters consisting of the monomeric red fluorescent protein (RFP) and either the C-terminal vacuolar sorting signal of phaseolin or the sequence-specific sorting signal of proricin. In transgenic Arabidopsis leaves, mature roots, and root tips, all TIP fusions localized to the tonoplast of the central vacuole and both of the lumenal RFP reporters were found within TIP-delimited vacuoles. In embryos from developing, mature, and germinating seeds, all three TIPs localized to the tonoplast of protein storage vacuoles. To determine the temporal TIP expression patterns and to rule out mistargeting due to overexpression, we generated plants expressing YFP fused to the complete genomic sequences of the three TIP isoforms. In transgenic Arabidopsis, γ-TIP expression was limited to vegetative tissues, but specifically excluded from root tips, whereas α-TIP was exclusively expressed during seed maturation. δ-TIP was expressed in vegetative tissues, but not root tips, at a later stage than γ-TIP. Our findings indicate that, in the Arabidopsis tissues analyzed, two different vacuolar sorting signals target soluble proteins to a single vacuolar location. Moreover, TIP isoform distribution is tissue and development specific, rather than organelle specific.
Global Expression Profiling Applied to the Analysis of Arabidopsis Stamen Development
Authors: Alves-Ferreira Márcio , Wellmer Frank , Banhara Aline , Kumar Vijaya , Riechmann José Luis , Meyerowitz Elliot M. 
Published: September 2007

Abstract
To obtain detailed information about gene expression during stamen development in Arabidopsis (Arabidopsis thaliana), we compared, by microarray analysis, the gene expression profile of wild-type inflorescences to those of the floral mutants apetala3, sporocyteless/nozzle, and male sterile1 (ms1), in which different aspects of stamen formation are disrupted. These experiments led to the identification of groups of genes with predicted expression at early, intermediate, and late stages of stamen development. Validation experiments using in situ hybridization confirmed the predicted expression patterns. Additional experiments aimed at characterizing gene expression specifically during microspore formation. To this end, we compared the gene expression profiles of wild-type flowers of distinct developmental stages to those of the ms1 mutant. Computational analysis of the datasets derived from this experiment led to the identification of genes that are likely involved in the control of key developmental processes during microsporogenesis. We also identified a large number of genes whose expression is prolonged in ms1 mutant flowers compared to the wild type. This result suggests that MS1, which encodes a putative transcriptional regulator, is involved in the stage-specific repression of these genes. Lastly, we applied reverse genetics to characterize several of the genes identified in the microarray experiments and uncovered novel regulators of microsporogenesis, including the transcription factor MYB99 and a putative phosphatidylinositol 4-kinase.
A Universal Expression/Silencing Vector in Plants
Authors: Peretz Yuval , Mozes-Koch Rita , Akad Fuad , Tanne Edna , Czosnek Henryk , Sela Ilan 
Published: September 2007

AbstractA universal vector (IL-60 and auxiliary constructs), expressing or silencing genes in every plant tested to date, is described. Plants that have been successfully manipulated by the IL-60 system include hard-to-manipulate species such as wheat (Triticum duram), pepper (Capsicum annuum), grapevine (Vitis vinifera), citrus, and olive (Olea europaea). Expression or silencing develops within a few days in tomato (Solanum lycopersicum), wheat, and most herbaceous plants and in up to 3 weeks in woody trees. Expression, as tested in tomato, is durable and persists throughout the life span of the plant. The vector is, in fact, a disarmed form of Tomato yellow leaf curl virus, which is applied as a double-stranded DNA and replicates as such. However, the disarmed virus does not support rolling-circle replication, and therefore viral progeny single-stranded DNA is not produced. IL-60 does not integrate into the plant's genome, and the construct, including the expressed gene, is not heritable. IL-60 is not transmitted by the Tomato yellow leaf curl virus's natural insect vector. In addition, artificial satellites were constructed that require a helper virus for replication, movement, and expression. With IL-60 as the disarmed helper “virus,” transactivation occurs, resulting in an inducible expressing/silencing system. The system's potential is demonstrated by IL-60-derived suppression of a viral-silencing suppressor of Grapevine virus A, resulting in Grapevine virus A-resistant/tolerant plants.
The Exposed N-Terminal Tail of the D1 Subunit Is Required for Rapid D1 Degradation during Photosystem II Repair inSynechocystissp PCC 6803
Authors: Komenda Josef , Tichý Martin , Prášil Ondřej , Knoppová Jana , Kuviková Stanislava , de Vries Remco , Nixon Peter J. 
Published: September 2007

AbstractThe selective replacement of photodamaged D1 protein within the multisubunit photosystem II (PSII) complex is an important photoprotective mechanism in chloroplasts and cyanobacteria. FtsH proteases are involved at an early stage of D1 degradation, but it remains unclear how the damaged D1 subunit is recognized, degraded, and replaced. To test the role of the N-terminal region of D1 in PSII biogenesis and repair, we have constructed mutants of the cyanobacterium Synechocystis sp PCC 6803 that are truncated at the exposed N terminus. Removal of 5 or 10 residues blocked D1 synthesis, as assessed in radiolabeling experiments, whereas removal of 20 residues restored the ability to assemble oxygen-evolving dimeric PSII complexes but inhibited PSII repair at the level of D1 degradation. Overall, our results identify an important physiological role for the exposed N-terminal tail of D1 at an early step in selective D1 degradation. This finding has important implications for the recognition of damaged D1 and its synchronized replacement by a newly synthesized subunit.
Revealed comparative advantage and competitiveness in services
Authors: Seyoum Belay 
Published: September 2007

PurposeThe purpose of this paper is to analyze the competitiveness of selected services: business, financial, transport and travel services in developing countries in relation to that of the rest of the world based on three indices of revealed comparative advantage.Design/methodology/approachThe study uses revealed comparative advantage (RCA) indices to measure developing countries' comparative advantages in selected services for the period 1998‐2003.FindingsStrong comparative advantages exist for many developing countries in transport, and travel services. There is substantial room for improvement in financial and business services. Trade liberalization and lack of adequate preparation appears to have resulted in a weakening of their comparative advantages over the years. However, their revealed comparative advantages remain, by and large, stable and do not show a fundamental shift in the structure of their comparative advantages.Originality/valueThere are no studies examining developing countries' comparative advantages in services. The findings and policy recommendations can be used by developing countries to improve the competitiveness of their service sectors.
Evaluating the penetration of capitalism in post‐socialist Ukraine
Authors: Williams Colin C. , Round John 
Published: September 2007

PurposeThe purpose of this paper is to evaluate critically the meta‐narrative that capitalism is becoming totalising and hegemonic. Grounded in an emerging corpus of post‐development thought that has deconstructed this discourse in relation to western economies and the majority (third) world, the purpose of this paper is to further contribute to this burgeoning critique by analysing the degree to which capitalism has penetrated a post‐socialist society, namely Ukraine.Design/methodology/approachTo analyse the penetration of capitalism, a survey is reported of the work practices of 600 households in a array of localities in Ukraine, conducted during 2005/2006 using face‐to‐face interviews.FindingsAnalysing the practices used by households to secure their livelihoods, the finding is that capitalism is far from hegemonic. Even when the formal economy is relied on either as their most important or second most important source of livelihood, it is nearly always combined with some other economic activity. A diverse portfolio of work practices is thus the norm rather than the exception with over 90 per cent of households relying on sources other than the formal market sphere as either their most important or second most important source of livelihood.Practical implicationsDisplaying the shallow penetration of capitalism in this array of localities in Ukraine, this paper reveals the need for a re‐representation of the realities of work in such post‐socialist societies so as to open up the feasibility of, and possibilities for, alternative futures for work.Originality/valueThis paper reports the first evaluation of the extent to which capitalism has penetrated work practices in post‐socialist Ukraine.
Evaluating the competitive market efficiency of top listed companies in Egypt
Authors: Mostafa Mohamed M. 
Published: September 2007

PurposeThe purpose of the research presented in this paper is to measure the relative market efficiency of the top listed companies in Egypt.Design/methodology/approachApplying a two‐stage approach, this study uses production frontier analysis (PFA) to measure the relative market efficiency of 62 listed companies in Egypt, and Tobit regression to examine the dependence of efficiency on the specific operating environment of these companies.FindingsThe results indicate that the performance of several companies is sub‐optimal, suggesting the potential for significant improvements over both profitability and marketability dimensions. Separate benchmarks were derived for possible reductions in resources used, and the results indicate that several companies deploy a much larger number of employees than required by a best practice company, and significant savings are possible on this account.Originality/valueFrom a policy perspective, this study highlights the economic importance of encouraging increased market efficiency throughout the business sector in Egypt.
Perceived environmental uncertainty, supply chain purchasing strategy, and use of MAS information
Authors: Agbejule Adebayo , Burrowes Ashley 
Published: September 2007

PurposeThe purpose of this paper is to investigate the relationship between perceived environmental uncertainty (PEU), supplier development (SUD) and the use of broad scope management accounting systems (MAS) information. In recent years, many companies have come to recognize the important role supply chain purchasing strategy plays in achieving competitive advantage. One of the key components of the supply chain purchasing strategy is supplier development. In addition, there have been calls for research into how changes in supply chain management affect the use of MAS.Design/methodology/approachAbout 78 managers from different organizations participated in this Finnish study. Using operations management and accounting literature, four hypotheses were proposed in the study. Data were collected from managers using a mail‐out questionnaire.FindingsThe results revealed that PEU is a determinant of SUD, which, in turn, is a determinant of the use of MAS. In other words, SUD plays a mediating role in the relationship between PEU and the use of broad scope MAS information.Research limitations/implicationsThis paper describes the responses from 78 managers in medium to large size manufacturing firms in North‐Western Finland and consequently a caveat about generalizability is appropriate notwithstanding the high‐global esteem of Finnish manufacturing.Practical implicationsThe competitive production environment that exists today has forced many firms into lean production. This paper suggests that under such conditions of uncertainty the incorporation of SUD data into the MAS may prove very salutary.Originality/valueThe findings of this paper should prove useful to firms entertaining an upgrade and broadening the scope of their MAS to include supply chain management information, particularly as it relates to supplier development.
Professional accounting bodies' perceptions of ethical issues, causes of ethical failure and ethics education
Authors: Jackling Beverley , Cooper Barry J. , Leung Philomena , Dellaportas Steven 
Published: September 2007

PurposeGiven the calls for increased ethics education following recent corporate collapses, this paper aims to examine the significance of ethical issues that challenge the profession and, more specifically, professional accounting bodies.Design/methodology/approachThe study assesses the perceptions via an online survey of 66 professional accounting bodies worldwide in respect of ethical issues, potential causes of ethical failure and the need for ethics education.FindingsRespondents identified a number of important challenges including conflicts of interest, earnings management and whistle‐blowing. The findings also demonstrate strong support for participation in prescribing the nature of ethics education by members of professional accounting bodies.Research limitations/implicationsThe results of this study are based on feedback from 41 per cent of member bodies of the International Federation of Accountants (IFAC). Despite a number of follow‐up reminder notices, some regions are under‐represented in the responses to the survey distributed to the (then) 160 member bodies of IFAC. Geographic isolation and language limitations contributed to the failure to gain a higher response rate.Practical implicationsThe findings demonstrate that professional bodies support ethics education at the pre‐ and post‐qualifying levels of education and a willingness to take an active role in promoting ethics education to their members.Originality/valueBy addressing member bodies' attitudes to ethics education, this paper fills a gap in prior literature that has been restricted to addressing the attitudes of academics, students and business organisations.
Economic factors and psychiatric hospital beds – an analysis of historical trends
Authors: Ceccherini‐Nelli Alfonso , Priebe Stefan 
Published: September 2007

PurposeThe purpose of this paper is to explore the association between economic factors (consumer price index, real gross domestic product per capita, base discount rate, and rate of unemployment) and numbers of hospital psychiatric beds.Design/methodology/approachTime series analytical techniques (unit root and cointegration tests) were applied to two regional data sets from the nineteenth century (North Carolina, USA; Berkshire, UK) and three national data sets in the twentieth century (US; UK; Italy) to test the hypothesis of a relationship.FindingsAll data sets suggest a long‐run relationship between economic factors and psychiatric bed numbers. Increase of consumer price predicted a decrease of hospital beds (and vice versa) in all data sets and was the strongest predictor of changes in psychiatric bed numbers. Hence, economic factors appear to be an important driver for the supply of hospital beds.Research limitations/implicationsCointegration tests are not true causality tests as they only measure the ability to forecast the value of an X variable knowing the value of N other variables. Therefore, one cannot rule out that the relationship between economic factors and psychiatric hospital beds is an indirect one, caused by another unidentified factor. Also, this study alone does not provide evidence to decide whether economic factors mainly influence demand or supply, although various findings suggest the latter.Practical implicationsCPI is of particular significance for changes in psychiatric bed provision, and co‐integration tests are a useful method to explore such association.Originality/valueThis study is the first one to apply time series analytical techniques to explore the role of economic factors in the processes of psychiatric institutionalisation and deinstitutionalisation.