bluuebunny/crossref_metadata_2025_split huggingface dataset:
Does Lowering Glutamine Synthetase Activity in Nodules Modify Nitrogen Metabolism and Growth of Lotus japonicus?
Authors: Harrison Judith , Pou de Crescenzo Marie-Anne , Sené Olivier , Hirel Bertrand 
Published: September 2003

Abstract
A cDNA encoding cytosolic glutamine synthetase (GS) from Lotus japonicus was fused in the antisense orientation relative to the nodule-specific LBC3 promoter of soybean (Glycine max) and introduced into L. japonicus via transformation with Agrobacterium tumefaciens. Among the 12 independent transformed lines into which the construct was introduced, some of them showed diminished levels of GS1 mRNA and lower levels of GS activity. Three of these lines were selected and their T1 progeny was further analyzed both for plant biomass production and carbon and nitrogen (N) metabolites content under symbiotic N-fixing conditions. Analysis of these plants revealed an increase in fresh weight in nodules, roots and shoots. The reduction in GS activity was found to correlate with an increase in amino acid content of the nodules, which was primarily due to an increase in asparagine content. Thus, this study supports the hypothesis that when GS becomes limiting, other enzymes (e.g. asparagine synthetase) that have the capacity to assimilate ammonium may be important in controlling the flux of reduced N in temperate legumes such as L. japonicus. Whether these alternative metabolic pathways are important in the control of plant biomass production still remains to be fully elucidated.
Nodule-Specific Modulation of Glutamine Synthetase in Transgenic Medicago truncatula Leads to Inverse Alterations in Asparagine Synthetase Expression
Authors: Carvalho Helena G. , Lopes-Cardoso Inês A. , Lima Ligia M. , Melo Paula M. , Cullimore Julie V. 
Published: September 2003

Abstract
Transgenic Medicago truncatula plants were produced harboring chimeric gene constructs of the glutamine synthetase (GS) cDNA clones (MtGS1a or MtGS1b) fused in sense or antisense orientation to the nodule-specific leghemoglobin promoter Mtlb1. A series of transgenic plants were obtained showing a 2- to 4-fold alteration in nodule GS activity when compared with control plants. Western and northern analyses revealed that the increased or decreased levels of GS activity correlate with the amount of cytosolic GS polypeptides and transcripts present in the nodule extracts. An analysis of the isoenzyme composition showed that the increased or decreased levels of GS activity were attributable to major changes in the homo-octameric isoenzyme GS1a. Nodules of plants transformed with antisense GS constructs showed an increase in the levels of both asparagine synthetase (AS) polypeptides and transcripts when compared with untransformed control plants, whereas the sense GS transformants showed decreased AS transcript levels but polypeptide levels similar to control plants. The polypeptide abundance of other nitrogen metabolic enzymes NADH-glutamic acid synthase and aspartic acid amino-transferase as well as those of major carbon metabolic enzymes phosphoenolpyruvate carboxylase, carbonic anhydrase, and sucrose synthase were not affected by the GS-gene manipulations. Increased levels of AS polypeptides and transcripts were also transiently observed in nodules by inhibiting GS activity with phosphinothricin. Taken together, the results presented here suggest that GS activity negatively regulates the level of AS in root nodules of M. truncatula. The potential role of AS in assimilating ammonium when GS becomes limiting is discussed.
Sodium Influx and Accumulation in Arabidopsis
Authors: Essah Pauline A. , Davenport Romola , Tester Mark 
Published: September 2003

Abstract
Arabidopsis is frequently used as a genetic model in plant salt tolerance studies, however, its physiological responses to salinity remain poorly characterized. This study presents a characterization of initial Na+ entry and the effects of Ca2+ on plant growth and net Na+ accumulation in saline conditions. Unidirectional Na+ influx was measured carefully using very short influx times in roots of 12-d-old seedlings. Influx showed three components with distinct sensitivities to Ca2+, diethylpyrocarbonate, and osmotic pretreatment. Pharmacological agents and known mutants were used to test the contribution of different transport pathways to Na+ uptake. Influx was stimulated by 4-aminobutyric acid and glutamic acid; was inhibited by flufenamate, quinine, and cGMP; and was insensitive to modulators of K+ and Ca2+ channels. Influx did not differ from wild type in akt1 and hkt1 insertional mutants. These data suggested that influx was mediated by several different types of nonselective cation channels. Na+ accumulation in plants grown in 50 mm NaCl was strongly reduced by increasing Ca2+ activity (from 0.05-3.0 mm), and plant survival was improved. However, plant biomass was not affected by shoot Na+ concentration, suggesting that in Arabidopsis Na+ toxicity is not dependent on shoot Na+ accumulation. These data suggest that Arabidopsis is a good model for investigation of Na+ transport, but may be of limited utility as a model for the study of Na+ toxicity.
Metabolic Profiling of Transgenic Tomato Plants Overexpressing Hexokinase Reveals That the Influence of Hexose Phosphorylation Diminishes during Fruit Development
Authors: Roessner-Tunali Ute , Hegemann Björn , Lytovchenko Anna , Carrari Fernando , Bruedigam Claudia , Granot David , Fernie Alisdair R. 
Published: September 2003

Abstract
We have conducted a comprehensive metabolic profiling on tomato (Lycopersicon esculentum) leaf and developing fruit tissue using a recently established gas chromatography-mass spectrometry profiling protocol alongside conventional spectrophotometric and liquid chromatographic methodologies. Applying a combination of these techniques, we were able to identify in excess of 70 small-M r metabolites and to catalogue the metabolite composition of developing tomato fruit. In addition to comparing differences in metabolite content between source and sink tissues of the tomato plant and after the change in metabolite pool sizes through fruit development, we have assessed the influence of hexose phosphorylation through fruit development by analyzing transgenic plants constitutively overexpressing Arabidopsis hexokinase AtHXK1. Analysis of the total hexokinase activity in developing fruits revealed that both wild-type and transgenic fruits exhibit decreasing hexokinase activity with development but that the relative activity of the transgenic lines with respect to wild type increases with development. Conversely, both point-by-point and principal component analyses suggest that the metabolic phenotype of these lines becomes less distinct from wild type during development. In summary, the data presented in this paper demonstrate that the influence of hexose phosphorylation diminishes during fruit development and highlights the importance of greater temporal resolution of metabolism.
Members of the Arabidopsis-SKP1-like Gene Family Exhibit a Variety of Expression Patterns and May Play Diverse Roles in Arabidopsis
Authors: Zhao Dazhong , Ni Weimin , Feng Baomin , Han Tianfu , Petrasek Megan G. , Ma Hong 
Published: September 2003

Abstract
Ubiquitin-mediated proteolysis by the proteasome is a critical regulatory mechanism controlling many biological processes. In particular, SKP1, cullin/CDC53, F-box protein (SCF) complexes play important roles in selecting substrates for proteolysis by facilitating the ligation of ubiquitin to specific proteins. In plants, SCF complexes have been found to regulate auxin responses and jasmonate signaling and may be involved in several other processes, such as flower development, circadian clock, and gibberellin signaling. Although 21 Skp1-related genes, called Arabidopsis-SKP1-like (ASK), have been uncovered in the Arabidopsis genome, ASK1 is the only gene that has been analyzed genetically. As a first step toward understanding their functions, we tested for expression of 20 ASK genes using reverse transcription-polymerase chain reaction experiments. Also, we examined the expression patterns of 11 ASK genes by in situ hybridizations. The ASK genes exhibit a spectrum of expression levels and patterns, with a large subset showing expression in the flower and/or fruit. In addition, the ASK genes that have similar sequences tend to have similar expression patterns. On the basis of the expression results, we selectively suppressed the expression of a few ASK genes using RNA interference. Compared with the ask1 mutant, the strong ASK1 RNA interference (RNAi) line exhibited similar or enhanced phenotypes in both vegetative and floral development, whereas ASK11 RNAi plants had normal vegetative growth but mild defects in flower development. The diverse expression patterns and distinct defects observed in RNAi plants suggest that the ASK gene family may collectively perform a range of functions and may regulate different developmental and physiological processes.
The polycotyledon Mutant of Tomato Shows Enhanced Polar Auxin Transport
Authors: Al-Hammadi Arif S.A. , Sreelakshmi Yellamaraju , Negi Sangeeta , Siddiqi Imran , Sharma Rameshwar 
Published: September 2003

Abstract
The polycotyledon mutant of tomato (Lycopersicon esculentum L. cv Ailsa Craig) showed altered development during embryogenesis and during vegetative and reproductive phases. The phenotype was pleiotropic and included the formation of extra cotyledons, changes in leaf shape, increased number of flowers (indeterminacy) with abnormal floral organs, the formation of epiphyllous structures, and altered gravitropism. The earliest defects were observed at the transition from the globular to the heart stage of embryogenesis with the formation of multiple cotyledons. Epidermal cells in the mutant embryo were smaller and less expanded compared with wild type. Examination of polar auxin transport (PAT) showed a striking enhancement in the case of the mutant. Increase in PAT did not appear to be caused by a decrease in flavonoids because the mutant had normal flavonoid levels. Application of 2,3,5-triiodobenzoic acid, an inhibitor of polar transport of auxin, rescued postgermination phenotypes of young seedlings. Our analysis reveals a level of control that negatively regulates PAT in tomato and its contribution to plant development and organogenesis.
Emergence of cyclonic structures due to the interaction between near‐inertial oscillations and mesoscale eddies
Authors: Klein Patrice , Hua Bach Lien , Carton Xavier 
Published: September 2003

AbstractWe show that mesoscale eddies, through their effects on near‐inertial oscillations, can induce a spatially heterogeneous diffusion that depends on the vorticity sign. In turn, this heterogeneous diffusion breaks the cyclone–anticyclone symmetry on small time‐scales (compared to the diffusive time‐scale) and favours the emergence of cyclonic structures. Copyright © 2003 Royal Meteorological Society
AIRS channel selection for CO2 and other trace‐gas retrievals
Authors: Crevoisier Cyril , Chedin Alain , Scott Noelle A. 
Published: September 2003

AbstractNew high‐resolution infrared sounders, such as the National Aeronautics and Space Administration's Aqua satellite Atmospheric Infrared Sounder (AIRS) or the European Meteorological Satellite systems, MetOp Infrared Atmospheric Sounding Instrument (IASI), are expected to improve our capability to monitor atmospheric carbon dioxide (CO2) and other trace‐gas concentrations from space. As they present thousands of channels, the first problem arising is the selection of a set of channels presenting the best properties to retrieve these concentrations. A new method, the Optimal Sensitivity Profile (OSP) method, based on the study of the sensitivities of AIRS channels to variations in the vertical of the different atmospheric components, is proposed. It is then compared with two ‘classical’ methods based on the information content and the degrees of freedom for signal of the AIRS channels regarding CO2. Applying the OSP method to a set of 82 representative atmospheric situations obtained from the 2311 situations of the Thermodynamic Initial Guess Retrieval (TIGR) dataset, divided into three air masses (tropical, temperate and polar), and using simulated AIRS observations, a global set of 43 channels, well covering the whole atmospheric column, is selected for CO2 retrieval. The OSP method is finally used to select channels for retrieval of atmospheric nitrous oxide (N2O), carbon monoxide (CO) and methane (CH4) concentrations. Copyright © 2003 Royal Meteorological Society
Parallel decoding for burst error control codes
Authors: Fujiwara Eiji , Namba Kazuteru , Kitakami Masato 
Published: September 2003

AbstractIt is well known that sequential decoding methods for burst error control codes use Linear Feedback Shift Registers (LFSR). However, a parallel decoding method employing only combinational logic is preferable in certain applications, such as semiconductor memory systems and holographic memory systems, where a huge amount of data needs to be read or written at ultrahigh speed. This paper proposes a parallel decoding method for linear burst error control codes including the Fire code. In order to obtain the error pattern, this decoding method uses an inverse matrix of a nonsingular matrix which includes a sub‐matrix of the parity check matrix. Burst error correction is possible because correct burst error patterns are obtained only from frames that completely include the burst error pattern. Furthermore, this decoding method can also be applied to single byte error correcting codes with less hardware. The implementation of decoding circuits for burst and byte error control codes are illustrated in this paper. And their hardware complexity is also evaluated to show that the proposed method requires less hardware than the existing parallel decoding method. Finally, we will discuss about how the proposed decoding method can be extended to correct multiple burst or byte errors. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(1): 38–48, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10094
Design of IIR half‐band filters with arbitrary flatness and its application to filter banks
Authors: Yamashita Ryou , Zhang Xi , Yoshikawa Toshinori , Takei Yoshinori 
Published: September 2003

AbstractHalf‐band filters are important for applications to multirate signal processing and wavelets. Previously, FIR half‐band filters have mainly been treated. However, it should be recognized that the IIR filter can produce frequency characteristics similar to those of the FIR filter with a low order. Also, in the applications of filter banks and wavelets, design of a half‐band filter is needed in which the degree of flatness can be specified arbitrarily. In the present paper, a new design method is proposed for an IIR half‐band filter with an arbitrary degree of flatness. In the present design method, the analytical solution of the filter coefficients is given in the case of a maximally flat filter. Also, in the case of a specified degree of flatness, the amplitude error in the stopband can be specified in the design. Further, the stability of the filter is studied and then the minimum group delay for causal stability is clarified. Finally, the IIR half‐band filter is applied to the design of a two‐channel filter bank and the effectiveness of the present design method is proven. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(1): 10–18, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10114
Wavelet‐based perceptual watermarking with bit data embedded in still color images
Authors: Kino Masato , Wada Shigeo 
Published: September 2003

AbstractAs a way to protect copyright of digital content, researches into electronic watermarking have been carried out extensively. In this paper, an image watermarking method is proposed that can embed bit patterns with an arbitrary length by extending the wavelet‐based watermarking method based on the human visual system (HVS) proposed by Barni. For color images, weighting is provided by taking into account human visual characteristics in such a way that the visual effect on the brightness components is smaller. One of the characteristics of the present method is a significant improvement of convenience by using a long pseudorandom number sequence including bit data such as signatures, in contrast to the pseudorandom sequence without bit information used by Barni. Through simulations, it is verified that the proposed method has strong robustness to JPEG compression, cropping, color tone conversion, and mode deformation. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(1): 1–9, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10115
Induction of oxidative stress by L‐2‐hydroxyglutaric acid in rat brain
Authors: Latini Alexandra , Scussiato Karina , Borba Rosa Rafael , Leipnitz Guilhian , Llesuy Susana , Belló‐Klein Adriane , Dutra‐Filho Carlos Severo , Wajner Moacir 
Published: September 2003

AbstractL‐2‐hydroxyglutaric acid (LGA) is the biochemical hallmark of L‐2‐hydroxyglutaric aciduria (L‐OHGA), an inherited neurometabolic disorder characterized by progressive neurodegeneration with cerebellar and pyramidal signs, mental deterioration, epilepsy, and subcortical leukoencephalopathy. Because the underlying mechanisms of the neuropathology of this disorder are virtually unknown, in this study we tested the in vitro effect of LGA on various parameters of oxidative stress, namely, chemiluminescence, thiobarbituric acid‐reactive substances (TBA‐RS), protein carbonyl formation (PCF), total radical‐trapping antioxidant potential (TRAP), total antioxidant reactivity (TAR), and the activities of the antioxidant enzymes catalase, glutathione peroxidase, and superoxide dismutase in cerebellum and cerebral cortex of 30‐day‐old rats. LGA significantly increased chemiluminescence, TBA‐RS, and PCF measurements and markedly decreased TAR values in cerebellum, in contrast to TRAP and the activity of the antioxidant enzymes, which were not altered by the acid. Similar but less pronounced effects were provoked by LGA in cerebral cortex. Moreover, the LGA‐induced increase of TBA‐RS was significantly attenuated by melatonin (N‐acetyl‐5‐methoxytryptamine) and by the combinations of ascorbic acid plus Trolox (soluble α‐tocopherol) and of superoxide dismutase plus catalase but not by the inhibitor of nitric oxide synthase Nω‐nitro‐L‐arginine methyl ester (L‐NAME), creatine, or superoxide dismutase or catalase alone in either cerebral structure. The data indicate that LGA provokes oxidation of lipids and proteins and reduces the brain capacity to modulate efficiently the damage associated with an enhanced production of free radicals, possibly by inducing generation of superoxide and hydroxyl radicals, which are trapped by the scavengers used. Thus, in case these findings can be extrapolated to human L‐OHGA, it may be presumed that oxidative stress is involved in the pathophysiology of the brain damage observed in this disorder. © 2003 Wiley‐Liss, Inc.
Calcium channel upregulation in response to activation of neurotrophin and surrogate neurotrophin receptor tyrosine kinases
Authors: Black Melony J. , Woo Yeunkyung , Rane Stanley G. 
Published: September 2003

AbstractModulation of calcium channel expression and function in the context of neurotrophin induced neuronal differentiation remains incompletely understood at a mechanistic level. We addressed this issue in the PC12 model neuronal system using patch clamp electrophysiology combined with ectopic expression of the human β platelet‐derived growth factor (βPDGF) receptor as a surrogate neurotrophin receptor system. PC12 cells ectopically expressing the human βPDGF receptor were treated with PDGF or nerve growth factor (NGF) for up to 7 days, and Ca2+ channel subtype expression was analyzed using selective pharmacological agents in both whole‐cell and cell‐attached single channel patch clamp configurations. PDGF‐induced upregulation of N‐ and P/Q‐type Ca2+ channel currents completely mimicked upregulation of these currents caused by NGF stimulation of the endogenous TrkA receptor tyrosine kinase (RTK). Neither PDGF nor NGF significantly altered L‐ or R‐type currents. Single channel recordings together with immunocytochemistry implied that growth factor‐induced increases in whole‐cell Ca2+ currents were a result of synthesis of new channels, and that whereas increased N channel density was apparent in the soma, additional P/Q channels distributed preferentially to extrasomal locations, most likely the proximal neurites. Finally, specific signaling‐deficient mutant forms of the βPDGF receptor were used to show that activation of Src, PI3‐kinase, RasGAP, PLCγ or SHP‐2 (some of which are implicated in certain other aspects of PC12 cell differentiation) by RTKs is not required for growth factor‐induced Ca2+ channel upregulation. In contrast, activation of the Ras‐related G‐protein Rap1 was found critical to this process. © 2003 Wiley‐Liss, Inc.
Market expansion strategy: development of a conceptual market expansion decision scorecard
Authors: Robinson Gary J. , Lundstrom William J. 
Published: September 2003

Abstract

Research related to market expansion strategy has primarily focused on assessing the ‘fit’ between the organization and external factors such as market attractiveness, competitive advantage and risk, with minimal attention to internal factors such as organizational structure, management systems and corporate culture.
The external factors are key ingredients in the formulation of a plan, however the internal factors are key drivers to the successful implementation of such a plan.
A review of the literature on market expansion strategy theory is examined to identify the most appropriate theoretical base for developing an integrated model for assessing various market expansion strategies based on external and internal factors.
The relationship among internal and external factors and the resources, risk and control inherent to each mode of market expansion are used to develop a model which provides direction as to the appropriate market expansion decision.

Copyright © 2003 John Wiley & Sons, Ltd.
Design issues and performance improvements in routing strategy on the Internet workflow
Authors: Yang Shin‐Jer 
Published: September 2003

AbstractThis paper addresses some performance issues for routing design, and influencing parameters for workflow routing. In particular, we propose an adaptive routing control algorithm of workflow systems. First, we finalize some main factors that affect the workflow's performance. Then, we design a new routing control algorithm, called ARC (Adaptive Routing Control), which is based on Dijkstra's algorithm to find the efficient and flexible path of workflow. Hence, we develop a simulation program to evaluate the performance of the ARC algorithm and other two routing methods. Consequently, our results indicate that the performance of ARC is much better than other two conventional routing approaches. Copyright © 2003 John Wiley & Sons, Ltd.
Solution strategies for the delamination analysis based on a combination of local‐control arc‐length and line searches
Authors: Alfano G. , Crisfield M. A. 
Published: September 2003

AbstractThe paper describes a local‐control arc‐length method which can be combined with various forms of line‐search procedure. In particular, a new ‘double‐line‐search’ method is developed, which significantly improves the solution procedure and turns out to be efficient and robust. Although the potential range of applications is wide, the method is here limited to the finite element analysis of delamination in a laminated composite using a cohesive‐zone model combined with interface elements. Three problems have been analysed and comparisons have been made with experimental results. Copyright © 2003 John Wiley & Sons, Ltd.