bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurements of Label Free Protein Concentration and Conformational Changes Using a Microfluidic UV‐LED Method
Authors: Lee Jinkee , Tripathi Anubhav 
Published: November 2007

AbstractThis paper presents a microchip‐based system for measuring concentrations and dynamic conformational changes in proteins without any use of extrinsic fluorescent labeling. The microchannel flow of protein molecules was integrated with an ultraviolet light‐emitting diode (UV‐LED, λex = 295 nm) and a photodetector (λem = 330 nm). The intrinsic fluorescence shift, arising from selectively exciting aromatic amino acid tryptophan (Trp), was monitored to quantify refolding pathways by dynamically varying the concentration of the chemical denaturant, urea. Short diffusion distances in the microchannel result in rapid equilibrium between protein and titrating solutions. Dilutions on the chip were tightly regulated using pressure controls, rather than syringe‐based flow, as verified with extensive on‐chip tracer dye controls. The concentrations of proteins were first measured using the UV‐LED microfluidic platform, and the data showed detection limits down to 72, 128, and 250 nM for tryptophan, bovine serum albumin (BSA), and bovine carbonic anhydrase (BCA), respectively. To validate the protein assay method, folding transition experiments were performed using a well‐characterized protein, BSA. The microchip protein refolding transitions using intrinsic fluorescence were well‐correlated with conventional fluorometer experiments. The microfluidic platform facilitates refolding studies to identify rapidly the optimal folding strategy for a protein using small quantities of material. The technique offers a real alternative to bulky microfluidic systems consisting of large and expensive laser‐based designs.
High‐Level Transient Production of a Heterologous Protein in Plants by Optimizing Induction of a Chemically Inducible Viral Amplicon Expression System
Authors: Plesha Michael A. , Huang Ting‐Kuo , Dandekar Abhaya M. , Falk Bryce W. , McDonald Karen A. 
Published: November 2007

AbstractWe have demonstrated that the method of chemical induction using a chemically inducible viral amplicon expression system can be optimized to increase expression of a heterologous protein in plants. A cucumber mosaic virus inducible viral amplicon (CMViva) expression system was used to transiently produce a recombinant human blood protein, α‐1‐antitrypsin (AAT), by co‐infiltrating intact and detached Nicotiana benthamiana leaves with two Agrobacterium tumefaciens strains, one containing the CMViva expression cassette carrying the AAT gene and the other containing a binary vector carrying the gene silencing suppressor p19. Infiltrated plants were induced by either topical applications or pressure injections and inducer was applied at either a single or multiple time points. Applying induction solution every 2 days via topical application resulted in increasing maximum levels of biologically functional rAAT from 0.71% to 1.3% of the total soluble protein (TSP) in detached plant leaves, a 1.8‐fold improvement. Multiple applications of induction solution via pressure injection into intact leaves resulted in maximum levels of biologically functional rAAT being elevated 3‐fold up to 2.4% of TSP compared to 0.8% of TSP when using the conventional method of a single topical application, and expression levels remained high 6 days post‐induction. Overall production of rAAT in intact leaves was found to have a maximum level of 5.8% of TSP or 390 mg rAAT per kg leaf tissue when applying multiple injections of chemical induction solution.
Powdery Mildew Induces Defense-Oriented Reprogramming of the Transcriptome in a Susceptible But Not in a Resistant Grapevine
Authors: Fung Raymond W.M. , Gonzalo Martin , Fekete Csaba , Kovacs Laszlo G. , He Yan , Marsh Ellen , McIntyre Lauren M. , Schachtman Daniel P. , Qiu Wenping 
Published: November 2007

AbstractGrapevines exhibit a wide spectrum of resistance to the powdery mildew fungus (PM), Erysiphe necator (Schw.) Burr., but little is known about the transcriptional basis of the defense to PM. Our microscopic observations showed that PM produced less hyphal growth and induced more brown-colored epidermal cells on leaves of PM-resistant Vitis aestivalis ‘Norton’ than on leaves of PM-susceptible Vitis vinifera ‘Cabernet sauvignon’. We found that endogenous salicylic acid levels were higher in V. aestivalis than in V. vinifera in the absence of the fungus and that salicylic acid levels increased in V. vinifera at 120 h postinoculation with PM. To test the hypothesis that gene expression differences would be apparent when V. aestivalis and V. vinifera were mounting a response to PM, we conducted a comprehensive Vitis GeneChip analysis. We examined the transcriptome at 0, 4, 8, 12, 24, and 48 h postinoculation with PM. We found only three PM-responsive transcripts in V. aestivalis and 625 in V. vinifera. There was a significant increase in the abundance of transcripts encoding ENHANCED DISEASE SUSCEPTIBILITY1, mitogen-activated protein kinase kinase, WRKY, PATHOGENESIS-RELATED1, PATHOGENESIS-RELATED10, and stilbene synthase in PM-infected V. vinifera, suggesting an induction of the basal defense response. The overall changes in the PM-responsive V. vinifera transcriptome also indicated a possible reprogramming of metabolism toward the increased synthesis of the secondary metabolites. These results suggested that resistance to PM in V. aestivalis was not associated with overall reprogramming of the transcriptome. However, PM induced defense-oriented transcriptional changes in V. vinifera.
A Versatile Transposon-Based Activation Tag Vector System for Functional Genomics in Cereals and Other Monocot Plants
Authors: Qu Shaohong , Desai Aparna , Wing Rod , Sundaresan Venkatesan 
Published: November 2007

Abstract
Transposon insertional mutagenesis is an effective alternative to T-DNA mutagenesis when transformation through tissue culture is inefficient as is the case for many crop species. When used as activation tags, transposons can be exploited to generate novel gain-of-function phenotypes without transformation and are of particular value in the study of polyploid plants where gene knockouts will not have phenotypes. We have developed an in cis-activation-tagging Ac-Ds transposon system in which a T-DNA vector carries a Dissociation (Ds) element containing 4× cauliflower mosaic virus enhancers along with the Activator (Ac) transposase gene. Stable Ds insertions were selected using green fluorescent protein and red fluorescent protein genes driven by promoters that are functional in maize (Zea mays) and rice (Oryza sativa). The system has been tested in rice, where 638 stable Ds insertions were selected from an initial set of 26 primary transformants. By analysis of 311 flanking sequences mapped to the rice genome, we could demonstrate the wide distribution of the elements over the rice chromosomes. Enhanced expression of rice genes adjacent to Ds insertions was detected in the insertion lines using semiquantitative reverse transcription-PCR method. The in cis-two-element vector system requires minimal number of primary transformants and eliminates the need for crossing, while the use of fluorescent markers instead of antibiotic or herbicide resistance increases the applicability to other plants and eliminates problems with escapes. Because Ac-Ds has been shown to transpose widely in the plant kingdom, the activation vector system developed in this study should be of utility more generally to other monocots.
Nitrate Efflux at the Root Plasma Membrane: Identification of anArabidopsisExcretion Transporter
Authors: Segonzac Cécile , Boyer Jean-Christophe , Ipotesi Emilie , Szponarski Wojciech , Tillard Pascal , Touraine Brigitte , Sommerer Nicolas , Rossignol Michel , Gibrat Rémy 
Published: November 2007

AbstractRoot NO3 − efflux to the outer medium is a component of NO3 − net uptake and can even overcome influx upon various stresses. Its role and molecular basis are unknown. Following a functional biochemical approach, NAXT1 (for NITRATE EXCRETION TRANSPORTER1) was identified by mass spectrometry in the plasma membrane (PM) of Arabidopsis thaliana suspension cells, a localization confirmed using a NAXT1–Green Fluorescent Protein fusion protein. NAXT1 belongs to a subclass of seven NAXT members from the large NITRATE TRANSPORTER1/PEPTIDE TRANSPORTER family and is mainly expressed in the cortex of mature roots. The passive NO3 − transport activity (K m = 5 mM) in isolated root PM, electrically coupled to the ATP-dependant H+-pumping activity, is inhibited by anti-NAXT antibodies. In standard culture conditions, NO3 − contents were altered in plants expressing NAXT-interfering RNAs but not in naxt1 mutant plants. Upon acid load, unidirectional root NO3 − efflux markedly increased in wild-type plants, leading to a prolonged NO3 − excretion regime concomitant with a decrease in root NO3 − content. In vivo and in vitro mutant phenotypes revealed that this response is mediated by NAXT1, whose expression is upregulated at the posttranscriptional level. Strong medium acidification generated a similar response. In vitro, the passive efflux of NO3 − (but not of Cl−) was strongly impaired in naxt1 mutant PM. This identification of NO3 − efflux transporters at the PM of plant cells opens the way to molecular studies of the physiological role of NO3 − efflux in stressed or unstressed plants.
SAD2, an Importin β-Like Protein, Is Required for UV-B Response in Arabidopsis by Mediating MYB4 Nuclear Trafficking
Authors: Zhao Jinfeng , Zhang Wenhui , Zhao Yang , Gong Ximing , Guo Lei , Zhu Guoli , Wang Xuechen , Gong Zhizhong , Schumaker Karen S. , Guo Yan 
Published: November 2007

Abstract
We report that the Arabidopsis thaliana mutant sensitive to ABA and drought2 (sad2), which harbors a T-DNA insertion in an importin β-like gene, is more tolerant to UV-B radiation than the wild type. Analysis of cyclobutane pyrimidine dimer accumulation revealed that less DNA damage occurred in sad2 than in the wild type during UV-B treatment. No significant growth difference was observed between sad2 and the wild type when treated with the genotoxic drug methyl methanesulfonate, suggesting that SAD2 functions in UV-B protection rather than in DNA damage repair. Whereas the R2R3-type transcription repressor MYB4 has previously been shown to negatively regulate the transcription of cinnamate 4-hydroxylase (C4H) and thus to regulate the synthesis of sinapate esters, expression of both MYB4 and C4H and accumulation of UV-absorbing compounds were significantly higher in sad2 than in the wild type. MYB4 did not localize to the nucleus in the sad2 mutant, suggesting that SAD2 is required for MYB4 nuclear trafficking. SAD2 and MYB4 coimmunoprecipitated, indicating that these proteins localize in the same complex in vivo. MYB4 protein specifically bound to its own promoter in gel shift assays and repressed its own expression, demonstrating that MYB4 protein and mRNA are part of a negative autoregulatory loop. This feedback loop is altered in the sad2 mutant due to the absence of MYB4 protein in the nucleus, leading to the constitutive expression of MYB4 and C4H and resulting in accumulation of UV-absorbing pigments that shield the plant from UV-B radiation.
Evolution and Function of acis-Regulatory Module for Mesophyll-Specific Gene Expression in the C4 DicotFlaveria trinervia
Authors: Akyildiz Meryem , Gowik Udo , Engelmann Sascha , Koczor Maria , Streubel Monika , Westhoff Peter 
Published: November 2007

AbstractC4 photosynthesis presents a sophisticated integration of two complementary cell types, mesophyll and bundle sheath cells. It relies on the differential expression of the genes encoding the component enzymes and transporters of this pathway. The entry enzyme of C4 photosynthesis, phosphoenolpyruvate carboxylase (PEPC), is found exclusively in mesophyll cells, and the expression of the corresponding gene is regulated at the transcriptional level. In the C4 dicot Flaveria trinervia, the mesophyll-specific expression of the C4 PEPC gene (ppcA) depends on a 41-bp segment in the distal promoter region referred to as MEM1 (for mesophyll expression module1). Here, we show that a MEM1 sequence found in the orthologous ppcA gene from the C3 species Flaveria pringlei is not able to direct mesophyll-specific gene expression. The two orthologous MEM1 sequences of F. pringlei and F. trinervia differ at two positions, a G-to-A exchange and the insertion of the tetranucleotide CACT. Changes at these two positions in the C3 MEM1 sequence were necessary and sufficient to create a mesophyll-specificity element during C4 evolution. The MEM1 of F. trinervia enhances mesophyll expression and concomitantly represses expression in bundle sheath cells and vascular bundles.
Money demand function for Southeast Asian countries
Authors: Cheong Tang Tuck 
Published: November 2007

PurposeThe purpose of this paper is to empirically investigate the money demand function for five Southeast Asian countries, viz. Malaysia, Thailand, Singapore, the Philippines, and Indonesia.Design/methodology/approachThe ARDL modeling approach is employed because of its ability to incorporate both I(0) and I(1) regressors.FindingsThe results reveal that real M2 aggregate, real expenditure components, exchange rate, and inflation rate are cointegrated for Malaysia, the Philippines, and Singapore. The statistical significance of real income components suggests the bias of using single real income variable in money demand (M2 aggregate) specification of both short‐ and long‐run. The CUSUM and CUSUMSQ tests show that the estimated parameters are stable for the five Southeast Asian economies, except for Indonesia which is based on short‐run specification.Practical implicationsThese findings are important for policy makers in formulating monetary policy.Originality/valueBesides conventional determinants of money demand such as exchange rate and interest rate variables, this study considers the major components of final expenditure (GDP) – final consumption expenditures (private and government sectors), expenditures on investment goods, and exports as scale variables.
Export performance of developing countries under the Africa Growth and Opportunity Act
Authors: Seyoum Belay 
Published: November 2007

PurposeThe purpose of this study is to assess the implications of US trade preferences under the African Growth and Opportunity Act (AGOA) and its impact on beneficiary country exports.Design/methodology/approachThe approach is to use Wilcoxon signed rank test and time series regression analysis using ARIMA.FindingsThe results largely indicate that AGOA has a positive but not significant effect on beneficiary exports to the USA for all country groups. Its effect is also quite marginal on sectoral exports except for textiles and apparel. Similarly, AGOA's effect is positive but not significant for all major exporters except Lesotho.Originality/valueA proper understanding of this relationship will help donors and recipients devise appropriate policies to help encourage the growth and diversification of exports that is so vital for developing countries.
Career success
Authors: Ballout Hassan I. 
Published: November 2007

PurposeThe purpose of this paper is to review relevant literatures on career success and develop a theoretical framework and testable propositions concerning how human capital, person‐environment fit and organizational support relate to career success. Whilst acknowledging the substantial literature that has accumulated regarding the various antecedents and operationalizations involved in employees' career success, there is little research as how person‐environment fit and career success are related.Design/methodology/approachLiterature outlining approaches to career success is summarized and research at the intersection of person‐environment fit and organizational support/career success are reviewed. This is followed by a set of propositions based upon the antecedents of career success.FindingsIt is suggested that person‐environment fit and organizational support are important antecedents of career success. Knowledge of career changes and these antecedents help individuals and organizations manage career success.Research limitations/implicationsFuture research should examine empirically the linkages suggested by the paper along with other relationships asserted or implied by person‐environment fit and career success literature as mentioned in the paper.Practical implicationsBoth employers and employees may benefit from integrating different types of fit into the psychological contract because each fit will impact aspects of career success. Therefore, organizations need to select and develop employees that can easily adjust and fit into careers that are compatible with their work environments.Originality/valueThis paper contributes to the literature by being one of the first to examine the effects of different types of person‐environment fit on career success.
Information technology repositories and knowledge management processes
Authors: Franco Massimo , Mariano Stefania 
Published: November 2007

PurposeThe purpose of this paper is to address the impact of information technology repositories (ITR) in the implementation of KM processes, i.e. knowledge storage and retrieval.Design/methodology/approachA case study design is used. Data are collected through the use of individual semi‐structured interviews, observations and document analysis.FindingsThis study found that three factors were likely to influence the knowledge retrieval process from information technology repositories and that the process of storage was connected to three distinct events that happened before, during, and after the repository was introduced into the organization. Furthermore, it was also found that knowledge management processes, i.e. knowledge storage and retrieval, were connected to individual learning.Research limitations/implicationsThis study has limitations connected to empirical generalizability because it is a single case study research. Also, this study focuses only on two knowledge management processes, i.e. knowledge storage and retrieval.Practical implicationsFindings suggest the need for managers to recognize the influence of leadership on knowledge management processes, i.e. knowledge sharing and storage. Another implication is that, when an organization wants to make information technology repositories more effective, rules and templates should be implemented to correctly use and update such repositories.Originality/valueThis research identifies the connections between knowledge management processes, i.e. knowledge storage and retrieval and individual learning processes. It also suggests four strategies to implement in order to make information technology repositories more effective.
Implementation of KM strategies in the Malaysian telecommunication industry
Authors: Wei Chong Chin , Choy Chong Siong , Yew Wong Kuan 
Published: November 2007

PurposeThis purpose of this paper is to assess the perceived importance and actual implementation of four knowledge management (KM) strategies, i.e. culture; leadership; information technology; and measurement, in the Malaysian telecommunication industry.Design/methodology/approachData were collected from 289 telecommunication organizations in Malaysia and analyzed using indices and parametric statistics.FindingsThe paired t‐test results show significant differences among all the KM strategies in terms of their importance and actual implementation. Strategies such as technology, culture and leadership are moderately implemented, with measurement being the least implemented factor.Research limitations/implicationsThis paper focuses on KM implementation rather than on learning and knowledge utilization.Practical implicationsMalaysian telecommunication organizations should give equal attention to the implementation of all the four KM strategies. They need to have proper planning and overcome any problem or difficulty for the four KM strategies to be implemented smoothly, and subsequently narrow the gaps between the perceived importance and actual implementation of these strategies. Such viable practice will significantly help the government of Malaysia to achieve the K‐Economy status and Vision 2020.Originality/valueThis study is perhaps one of the first to empirically investigate and compare the perceived importance and actual implementation of the four KM strategies in the Malaysian telecommunication industry.
Value‐added knowledge management for financial performance
Authors: Sharma Ravi S. , Teng Yu Hui Priscilla , Tan Meng‐Wah 
Published: November 2007

PurposeThis paper aims to study the economic significance of using a blended business and knowledge strategy through the lens of conventional financial management before and after the implementation of KM initiatives in a knowledge‐intensive, high‐growth firm that had gone through business diversification through organic developments as well as mergers and acquisitions for over a decade.Design/methodology/approachThe economic value added (EVA) method is proposed as a measure of the effective usage of capital funding in the firm before and after its KM program. The extent of the economic impact due to the contributions of various KM strategies was analyzed using standard financial management reporting. This enabled the derivation of follow‐on KM initiatives that were consistent with the target objectives.FindingsThe EVA method was found to be valid and credible in determining the net impact of various KM initiatives. This was in a form that was comprehensible to top management and KM decision‐makers.Research limitations/implicationsKnowledge management as a strategic imperative has gained significance over the past decade for its ability to handle the complexity of information to further create, transfer and reuse intellectual capital. More importantly, KM is seen as the key business enabler across different enterprises for its ability to enhance competitiveness and shareholder value. The EVA method used in this paper has allowed the valuation of KM initiatives.Practical implicationsThe emergence of KM as a blended business strategy has hence proved to be vital for the sustainability of the knowledge‐driven business model that looks beyond the physical and financial into intellectual and social capital.Originality/valueThe paper presents a longitudinal case study of a fairly large East Asian conglomerate.
Effective educational process: a data‐mining approach
Authors: Ranjan Jayanthi , Malik Kamna 
Published: November 2007

PurposeThe purpose of this paper is to develop a holistic model for educational purposes using data‐mining techniques for exploring the effects of probable changes in processes related to admissions, course delivery and recruitments.Design/methodology/approachThe paper proposes a framework for an effective educational process using data‐mining techniques to uncover the hidden trends and patterns and making accuracy based predictions through a higher level of analytical sophistication in the process of counselling students.FindingsData‐mining tools are used in academia for capitalizing on the advances of information technology. This process improves research and academic decision making through uncovering hidden trends and patterns that predict using a combination of explicit knowledge base, sophisticated analytical skills and academic domain knowledge.Originality/valueThe paper presents a model using a data‐mining approach for academics.