bluuebunny/crossref_metadata_2025 huggingface dataset:
3-Methylcrotonyl-Coenzyme A Carboxylase Is a Component of the Mitochondrial Leucine Catabolic Pathway in Plants
Authors: Anderson Marc D. , Che Ping , Song Jianping , Nikolau Basil J. , Wurtele Eve Syrkin
Published: July 2002

3-Methylcrotonyl-coenzyme A carboxylase (MCCase) is a mitochondrial biotin-containing enzyme whose metabolic function is not well understood in plants. In soybean (Glycine max) seedlings the organ-specific and developmentally induced changes in MCCase expression are regulated by mechanisms that control the accumulation of MCCase mRNA and the activity of the enzyme. During soybean cotyledon development, when seed-storage proteins are degraded, leucine (Leu) accumulation peaks transiently at 8 d after planting. The coincidence between peak MCCase expression and the decline in Leu content provides correlative evidence that MCCase is involved in the mitochondrial catabolism of Leu. Direct evidence for this conclusion was obtained from radiotracer metabolic studies using extracts from isolated mitochondria. These experiments traced the metabolic fate of [U-14C]Leu and NaH14CO3, the latter of which was incorporated into methylglutaconyl-coenzyme A (CoA) via MCCase. These studies directly demonstrate that plant mitochondria can catabolize Leu via the following scheme: Leu → α-ketoisocaproate → isovaleryl-CoA → 3-methylcrotonyl-CoA → 3-methylglutaconyl-CoA → 3-hydroxy-3-methylglutaryl-CoA → acetoacetate + acetyl-CoA. These findings demonstrate for the first time, to our knowledge, that the enzymes responsible for Leu catabolism are present in plant mitochondria. We conclude that a primary metabolic role of MCCase in plants is the catabolism of Leu.
Borate-Rhamnogalacturonan II Bonding Reinforced by Ca2+ Retains Pectic Polysaccharides in Higher-Plant Cell Walls1
Authors: Kobayashi Masaru , Nakagawa Hironobu , Asaka Tomoyuki , Matoh Toru
Published: July 2002

The extent of in vitro formation of the borate-dimeric-rhamnogalacturonan II (RG-II) complex was stimulated by Ca2+. The complex formed in the presence of Ca2+ was more stable than that without Ca2+. A naturally occurring boron (B)-RG-II complex isolated from radish (Raphanus sativus L. cv Aokubi-daikon) root contained equimolar amounts of Ca2+ and B. Removal of the Ca2+ bytrans-1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid induced cleavage of the complex into monomeric RG-II. These data suggest that Ca2+ is a normal component of the B-RG-II complex. Washing the crude cell walls of radish roots with a 1.5% (w/v) sodium dodecyl sulfate solution, pH 6.5, released 98% of the tissue Ca2+ but only 13% of the B and 22% of the pectic polysaccharides. The remaining Ca2+ was associated with RG-II. Extraction of the sodium dodecyl sulfate-washed cell walls with 50 mmtrans-1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid, pH 6.5, removed the remaining Ca2+, 78% of B, and 49% of pectic polysaccharides. These results suggest that not only Ca2+ but also borate and Ca2+cross-linking in the RG-II region retain so-called chelator-soluble pectic polysaccharides in cell walls.
Nitrate-Ammonium Synergism in Rice. A Subcellular Flux Analysis1
Authors: Kronzucker Herbert J. , Siddiqi M. Yaeesh , Glass Anthony D.M. , Kirk Guy J.D.
Published: July 2002

Many reports have shown that plant growth and yield is superior on mixtures of NO3− and NH4+ compared with provision of either N source alone. Despite its clear practical importance, the nature of this N-source synergism at the cellular level is poorly understood. In the present study we have used the technique of compartmental analysis by efflux and the radiotracer 13N to measure cellular turnover kinetics, patterns of flux partitioning, and cytosolic pool sizes of both NO3− and NH4+ in seedling roots of rice (Oryza sativa L. cv IR72), supplied simultaneously with the two N sources. We show that plasma membrane fluxes for NH4+, cytosolic NH4+accumulation, and NH4+ metabolism are enhanced by the presence of NO3−, whereas NO3− fluxes, accumulation, and metabolism are strongly repressed by NH4+. However, net N acquisition and N translocation to the shoot with dual N-source provision are substantially larger than when NO3− or NH4+ is provided alone at identical N concentrations.
Antifreeze Proteins in Winter Rye Leaves Form Oligomeric Complexes1
Authors: Yu Xiao-Ming , Griffith Marilyn
Published: July 2002

Antifreeze proteins (AFPs) similar to three pathogenesis-related proteins, a glucanase-like protein (GLP), a chitinase-like protein (CLP), and a thaumatin-like protein (TLP), accumulate during cold acclimation in winter rye (Secale cereale) leaves, where they are thought to modify the growth of intercellular ice during freezing. The objective of this study was to characterize the rye AFPs in their native forms, and our results show that these proteins form oligomeric complexes in vivo. Nine proteins were separated by native-polyacrylamide gel electrophoresis from apoplastic extracts of cold-acclimated winter rye leaves. Seven of these proteins exhibited multiple polypeptides when denatured and separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. After isolation of the individual proteins, six were shown by immunoblotting to contain various combinations of GLP, CLP, and TLP in addition to other unidentified proteins. Antisera produced against individual cold-induced winter rye GLP, CLP, and TLP all dramatically inhibited glucanase activity in apoplastic extracts from cold-acclimated winter rye leaves, and each antiserum precipitated all three proteins. These results indicate that each of the polypeptides may be exposed on the surface of the protein complexes. By forming oligomeric complexes, AFPs may form larger surfaces to interact with ice, or they may simply increase the mass of the protein bound to ice. In either case, the complexes of AFPs may inhibit ice growth and recrystallization more effectively than the individual polypeptides.
Changed Properties of the Cytoplasmic Matrix Associated with Desiccation Tolerance of Dried Carrot Somatic Embryos. An in Situ Fourier Transform Infrared Spectroscopic Study1
Authors: Wolkers Willem F. , Tetteroo Frans A.A. , Alberda Mark , Hoekstra Folkert A.
Published: July 2002

Abscisic acid-pretreated carrot (Daucus carota) somatic embryos survive dehydration upon slow drying, but fast drying leads to poor survival of the embryos. To determine whether the acquisition of desiccation tolerance is associated with changes in the physical stability of the cytoplasm, in situ Fourier transform infrared microspectroscopy was used. Although protein denaturation temperatures were similar in the embryos after slow or fast drying, the extent of the denaturation was greater after fast drying. Slowly dried embryos are in a glassy state at room temperature, and no clearly defined glassy matrix was observed in the rapidly dried embryos. At room temperature the average strength of hydrogen bonding was much weaker in the rapidly dried than in the slowly dried embryos. We interpreted the molecular packing to be “less tight” in the rapidly dried embryos. Whereas sucrose (Suc) is the major soluble carbohydrate after fast drying, upon slow drying the trisaccharide umbelliferose accumulates at the expense of Suc. The possibly protective role of umbelliferose was tested on protein and phospholipid model systems, using Suc as a reference. Both umbelliferose and Suc form a stable glass with drying: They depress the transition temperature of dry liposomal membranes equally well, they both prevent leakage from dry liposomes after rehydration, and they protect a polypeptide that is desiccation sensitive. The similar protection properties in model systems and the apparent interchangeability of both sugars in viable, dry somatic embryos suggest no special role of umbelliferose in the improved physical stability of the slowly dried embryos. Also, during slow drying LEA (late-embryogenesisabundant) transcripts are expressed. We suggest that LEA proteins embedded in the glassy matrix confer stability to these slowly dried embryos.
Carbon Uptake and the Metabolism and Transport of Lipids in an Arbuscular Mycorrhiza1
Authors: Pfeffer Philip E. , Douds David D. , Bécard Guillaume , Shachar-Hill Yair
Published: July 2002

Both the plant and the fungus benefit nutritionally in the arbuscular mycorrhizal symbiosis: The host plant enjoys enhanced mineral uptake and the fungus receives fixed carbon. In this exchange the uptake, metabolism, and translocation of carbon by the fungal partner are poorly understood. We therefore analyzed the fate of isotopically labeled substrates in an arbuscular mycorrhiza (in vitro cultures of Ri T-DNA-transformed carrot [Daucus carota] roots colonized by Glomus intraradices) using nuclear magnetic resonance spectroscopy. Labeling patterns observed in lipids and carbohydrates after substrates were supplied to the mycorrhizal roots or the extraradical mycelium indicated that: (a)13C-labeled glucose and fructose (but not mannitol or succinate) are effectively taken up by the fungus within the root and are metabolized to yield labeled carbohydrates and lipids; (b) the extraradical mycelium does not use exogenous sugars for catabolism, storage, or transfer to the host; (c) the fungus converts sugars taken up in the root compartment into lipids that are then translocated to the extraradical mycelium (there being little or no lipid synthesis in the external mycelium); and (d) hexose in fungal tissue undergoes substantially higher fluxes through an oxidative pentose phosphate pathway than does hexose in the host plant.
Linking Development and Determinacy with Organic Acid Efflux from Proteoid Roots of White Lupin Grown with Low Phosphorus and Ambient or Elevated Atmospheric CO2 Concentration1
Authors: Watt Michelle , Evans John R.
Published: July 2002

White lupin (Lupinus albus L.) was grown in hydroponic culture with 1 μm phosphorus to enable the development of proteoid roots to be observed in conjunction with organic acid exudation. Discrete regions of closely spaced, determinate secondary laterals (proteoid rootlets) emerged in near synchrony on the same plant. One day after reaching their final length (4 mm), citrate exudation occurred over a 3-d pulse. The rate of exudation varied diurnally, with maximal rates during the photoperiod. At the onset of citrate efflux, rootlets had exhausted their apical meristems and had differentiated root hairs and vascular tissues along their lengths. Neither in vitro phosphoenolpyruvate carboxylase nor citrate synthase activity was correlated with the rate of citrate exudation. We suggest that an unidentified transport process, presumably at the plasma membrane, regulates citrate efflux. Growth with elevated (700 μL L−1) atmospheric [CO2] promoted earlier onset of rootlet determinacy by 1 d, resulting in shorter rootlets and citrate export beginning 1 d earlier as a 2-d diurnal pulse. Citrate was the dominant organic acid exported, and neither the rate of exudation per unit length of root nor the composition of exudate was altered by atmospheric [CO2].
Root Formation in Ethylene-Insensitive Plants
Authors: Clark David G. , Gubrium Erika K. , Barrett James E. , Nell Terril A. , Klee Harry J.
Published: July 2002

Experiments with ethylene-insensitive tomato (Lycopersicon esculentum) and petunia (Petunia ×hybrida) plants were conducted to determine if normal or adventitious root formation is affected by ethylene insensitivity. Ethylene-insensitive Never ripe (NR) tomato plants produced more belowground root mass but fewer aboveground adventitious roots than wild-type Pearson plants. Applied auxin (indole-3-butyric acid) increased adventitious root formation on vegetative stem cuttings of wild-type plants but had little or no effect on rooting of NR plants. Reduced adventitious root formation was also observed in ethylene-insensitive transgenic petunia plants. Applied 1-aminocyclopropane-1-carboxylic acid increased adventitious root formation on vegetative stem cuttings from NR and wild-type plants, but NR cuttings produced fewer adventitious roots than wild-type cuttings. These data suggest that the promotive effect of auxin on adventitious rooting is influenced by ethylene responsiveness. Seedling root growth of tomato in response to mechanical impedance was also influenced by ethylene sensitivity. Ninety-six percent of wild-type seedlings germinated and grown on sand for 7 d grew normal roots into the medium, whereas 47% of NR seedlings displayed elongated taproots, shortened hypocotyls, and did not penetrate the medium. These data indicate that ethylene has a critical role in various responses of roots to environmental stimuli.
Peroxisomal NADP-Dependent Isocitrate Dehydrogenase. Characterization and Activity Regulation during Natural Senescence
Authors: Corpas Francisco J. , Barroso Juan B. , Sandalio Luisa M. , Palma José M. , Lupiáñez José A. , del Rı́o Luis A.
Published: July 2002

The peroxisomal localization and characterization of NADP-dependent isocitrate dehydrogenase (perICDH) in young and senescent pea (Pisum sativum) leaves was studied by subcellular fractionation, kinetic analysis, immunoblotting, and immunoelectron microscopy. The subunit molecular mass for perICDH determined by immunoblotting was 46 kD. By isoelectric focusing (IEF) of the peroxisomal matrix fraction, the NADP-ICDH activity was resolved into four isoforms, perICDH-1 to perICDH-4, with isoelectric points (pIs) of 6.0, 5.6, 5.4, and 5.2, respectively. The kinetic properties of the NADP-ICDH in peroxisomes from young and senescent pea leaves were analyzed. The maximum initial velocity was the same in peroxisomes from young and senescent leaves, while the Michaelis constant value in senescent leaf peroxisomes was 11-fold lower than in young leaf peroxisomes. The protein levels of NADP-ICDH in peroxisomes were not altered during senescence. The kinetic behavior of this enzyme suggests a possible fine control of enzymatic activity by modulation of its Michaelis constant during the natural senescence of pea leaves. After embedding, electron microscopy immunogold labeling of NADP-ICDH confirmed that this enzyme was localized in the peroxisomal matrix. Peroxisomal NADP-ICDH represents an alternative dehydrogenase in these cell organelles and may be the main system for the reduction of NADP to NADPH for its re-utilization in the peroxisomal metabolism.
N-Acylethanolamines in Signal Transduction of Elicitor Perception. Attenuation of Alkalinization Response and Activation of Defense Gene Expression
Authors: Tripathy Swati , Venables Barney J. , Chapman Kent D.
Published: July 2002

In a recent study ofN-acylphosphatidylethanolamine (NAPE) metabolism in elicitor-treated tobacco (Nicotiana tabacum L.) cells, we identified a rapid release and accumulation of medium-chainN-acylethanolamines (NAEs) (e.g.N-myristoylethanolamine or NAE 14:0) and a compensatory decrease in cellular NAPE (K.D. Chapman, S. Tripathy, B. Venables, A.D. Desouza [1998] Plant Physiol 116: 1163–1168). In the present study, we extend this observation and report a 10- to 50-fold increase in NAE 14:0 content in leaves of tobacco (cv Xanthi) plants treated with xylanase or cryptogein elicitors. Exogenously supplied synthetic NAE species affected characteristic elicitor-induced and short- and long-term defense responses in cell suspensions of tobacco and long-term defense responses in leaves of intact tobacco plants. In general, synthetic NAEs inhibited elicitor-induced medium alkalinization by tobacco cells in a time- and concentration-dependent manner. Exogenous NAE 14:0 induced expression of phenylalanine ammonia lyase in a manner similar to fungal elicitors in both cell suspensions and leaves of tobacco. NAE 14:0, but not myristic acid, activated phenylalanine ammonia lyase expression at submicromolar concentrations, well within the range of NAE 14:0 levels measured in elicitor-treated plants. Collectively, these results suggest that NAPE metabolism, specifically, the accumulation of NAE 14:0, are part of a signal transduction pathway that modulates cellular defense responses following the perception of fungal elicitors.
Detoxification of Arsenic by Phytochelatins in Plants
Authors: Schmöger Marcus E.V. , Oven Matjaz , Grill Erwin
Published: July 2002

As is a ubiquitous element present in the atmosphere as well as in the aquatic and terrestrial environments. Arsenite and arsenate are the major forms of As intoxication, and these anions are readily taken up by plants. Both anions efficiently induce the biosynthesis of phytochelatins (PCs) ([γ-glutamate-cysteine]n-glycine) in vivo and in vitro. The rapid induction of the metal-binding PCs has been observed in cell suspension cultures of Rauvolfia serpentina, in seedlings of Arabidopsis, and in enzyme preparations of Silene vulgaris upon challenge to arsenicals. The rate of PC formation in enzyme preparations was lower compared with Cd-induced biosynthesis, but was accompanied by a prolonged induction phase that resulted finally in higher peptide levels. An approximately 3:1 ratio of the sulfhydryl groups from PCs to As is compatible with reported As-glutathione complexes. The identity of the As-induced PCs and of reconstituted metal-peptide complexes has unequivocally been demonstrated by electrospray ionization mass spectroscopy. Gel filtration experiments and inhibitor studies also indicate a complexation and detoxification of As by the induced PCs.
Analysis of Reductant Supply Systems for Ferredoxin-Dependent Sulfite Reductase in Photosynthetic and Nonphotosynthetic Organs of Maize
Authors: Yonekura-Sakakibara Keiko , Onda Yayoi , Ashikari Toshihiko , Tanaka Yoshikazu , Kusumi Takaaki , Hase Toshiharu
Published: July 2002

Sulfite reductase (SiR) catalyzes the reduction of sulfite to sulfide in chloroplasts and root plastids using ferredoxin (Fd) as an electron donor. Using purified maize (Zea mays L.) SiR and isoproteins of Fd and Fd-NADP+reductase (FNR), we reconstituted illuminated thylakoid membrane- and NADPH-dependent sulfite reduction systems. Fd I and L-FNR were distributed in leaves and Fd III and R-FNR in roots. The stromal concentrations of SiR and Fd I were estimated at 1.2 and 37 μm, respectively. The molar ratio of Fd III to SiR in root plastids was approximately 3:1. Photoreduced Fd I and Fd III showed a comparable ability to donate electrons to SiR. In contrast, when being reduced with NADPH via FNRs, Fd III showed a several-fold higher activity than Fd I. Fd III and R-FNR showed the highest rate of sulfite reduction among all combinations tested. NADP+decreased the rate of sulfite reduction in a dose-dependent manner. These results demonstrate that the participation of Fd III and high NADPH/NADP+ ratio are crucial for non-photosynthetic sulfite reduction. In accordance with this view, a cysteine-auxotrophicEscherichia coli mutant defective for NADPH-dependent SiR was rescued by co-expression of maize SiR with Fd III but not with Fd I.
Genotypical Differences in Aluminum Resistance of Maize Are Expressed in the Distal Part of the Transition Zone. Is Reduced Basipetal Auxin Flow Involved in Inhibition of Root Elongation by Aluminum?
Authors: Kollmeier Malte , Felle Hubert H. , Horst Walter J.
Published: July 2002

Short-term Al treatment (90 μm Al at pH 4.5 for 1 h) of the distal transition zone (DTZ; 1–2 mm from the root tip), which does not contribute significantly to root elongation, inhibited root elongation in the main elongation zone (EZ; 2.5–5 mm from the root tip) to the same extent as treatment of the entire maize (Zea mays) root apex. Application of Al to the EZ had no effect on root elongation. Higher genotypical resistance to Al applied to the entire root apex, and specifically to the DTZ, was expressed by less inhibition of root elongation, Al accumulation, and Al-induced callose formation, primarily in the DTZ. A characteristic pH profile along the surface of the root apex with a maximum of pH 5.3 in the DTZ was demonstrated. Al application induced a substantial flattening of the pH profile moreso in the Al-sensitive than in the Al-resistant cultivar. Application of indole-3-acetic acid to the EZ but not to the meristematic zone significantly alleviated the inhibition of root elongation induced by the application of Al to the DTZ. Basipetal transport of exogenously applied [3H]indole-3-acetic acid to the meristematic zone was significantly inhibited by Al application to the DTZ in the Al-sensitive maize cv Lixis. Our results provide evidence that the primary mechanisms of genotypical differences in Al resistance are located within the DTZ, and suggest a signaling pathway in the root apex mediating the Al signal between the DTZ and the EZ through basipetal auxin transport.
Comparative Analysis of Expressed Sequences in Phytophthora sojae
Authors: Qutob Dinah , Hraber Peter T. , Sobral Bruno W.S. , Gijzen Mark
Published: July 2002

Phytophthora sojae (Kaufmann and Gerdemann) is an oomycete that causes stem and root rot on soybean (Glycine max L. Merr) plants. We have constructed three cDNA libraries using mRNA isolated from axenically grown mycelium and zoospores and from tissue isolated from plant hypocotyls 48 h after inoculation with zoospores. A total of 3,035 expressed sequence tags (ESTs) were generated from the three cDNA libraries, representing an estimated 2,189 cDNA transcripts. The ESTs were classified according to putative function based on similarity to known proteins, and were analyzed for redundancy within and among the three source libraries. Distinct expression patterns were observed for each library. By analysis of the percentage G+C content of the ESTs, we estimate that two-thirds of the ESTs from the infected plant library are derived from P. sojae cDNA transcripts. The ESTs originating from this study were also compared with a collection of Phytophthora infestans ESTs and with all other non-human ESTs to assess the similarity of the P. sojae sequences to existing EST data. This collection of cDNA libraries, ESTs, and accompanying annotation will provide a new resource for studies on oomycetes and on soybean responses to pathogen challenge.
Aluminum Accumulation at Nuclei of Cells in the Root Tip. Fluorescence Detection Using Lumogallion and Confocal Laser Scanning Microscopy
Authors: Silva Ivo R. , Smyth T. Jot , Moxley Dana F. , Carter Thomas E. , Allen Nina S. , Rufty Thomas W.
Published: July 2002

The mechanistic basis for Al toxicity effects on root growth is still a matter of speculation, but it almost certainly involves decreased cell division at the root apex. In this series of experiments, we attempt to determine whether Al enters meristematic cells and binds to nuclei when roots are exposed to a low Al3+ activity in solution. The methodology involved the use of the Al-sensitive stain lumogallion (3-[2,4 dihydroxyphenylazo]-2-hydroxy-5-chlorobenzene sulfonic acid), the DNA stain 4′,6-diamino-phenylindole, and confocal laser scanning microscopy. Soybean (Glycine max L. Merr.) cv Young (Al-sensitive) and PI 416937 (Al-tolerant) genotypes were exposed to 1.45 μm Al3+ for periods ranging from 30 min to 72 h, and then washed with 10 mm citrate to remove apoplastic Al. Fluorescence images show that within 30 min Al entered cells of the sensitive genotype and accumulated at nuclei in the meristematic region of the root tip. Substantial Al also was present at the cell periphery. The images indicated that the Al-tolerant genotype accumulated lower amounts of Al in meristematic and differentiating cells of the root tip and their cell walls. Collectively, the results support an important role for exclusion in Al tolerance.
Characterization of Auxin Conjugates in Arabidopsis. Low Steady-State Levels of Indole-3-Acetyl-Aspartate, Indole-3-Acetyl-Glutamate, and Indole-3-Acetyl-Glucose
Authors: Tam Yuen Yee , Epstein Ephraim , Normanly Jennifer
Published: July 2002

Amide-linked indole-3-acetic acid (IAA) conjugates constitute approximately 90% of the IAA pool in the dicot Arabidopsis, whereas ester-linked conjugates and free IAA account for approximately 10% and 1%, respectively when whole seedlings are measured. We show here that IAA-aspartate Asp, IAA-glutamate (Glu), and IAA-glucose (Glc) are present at low levels in Arabidopsis. Nine-day-old wild-type Arabidopsis seedlings yielded 17.4 ± 4.6 ng g−1fresh weight IAA-Asp and 3.5 ± 1.6 ng g−1 fresh weight IAA-Glu, and IAA-Glc was present at 7 to 17 ng g−1fresh weight in 12-d-old wild-type seedlings. Total IAA content in 9-d-old Arabidopsis seedlings was 1,200 ± 178 ng g−1fresh weight, so these three IAA conjugates together made up only 3% of the conjugate pool throughout the whole plant. We detected less than wild-type levels of IAA-Asp and IAA-Glu (7.8 ± 0.4 ng g−1 fresh weight and 1.8 ± 0.3 ng g−1fresh weight, respectively) in an Arabidopsis mutant that accumulates conjugated IAA. Our results are consistent with IAA-Asp, IAA-Glu, and IAA-Glc being either minor, transient, or specifically localized IAA metabolites under normal growth conditions and bring into question the physiological relevance of IAA-Asp accumulation in response to high concentrations of exogenous IAA.
The Mechanical Properties and Molecular Dynamics of Plant Cell Wall Polysaccharides Studied by Fourier-Transform Infrared Spectroscopy
Authors: Wilson Reginald H. , Smith Andrew C. , Kačuráková Marta , Saunders Paul K. , Wellner Nikolaus , Waldron Keith W.
Published: July 2002

Polarized one- and two-dimensional infrared spectra were obtained from the epidermis of onion (Allium cepa) under hydrated and mechanically stressed conditions. By Fourier-transform infrared microspectroscopy, the orientation of macromolecules in single cell walls was determined. Cellulose and pectin exhibited little orientation in native epidermal cell walls, but when a mechanical stress was placed on the tissue these molecules showed distinct reorientation as the cells were elongated. When the stress was removed the tissue recovered slightly, but a relatively large plastic deformation remained. The plastic deformation was confirmed in microscopic images by retention of some elongation of cells within the tissue and by residual molecular orientation in the infrared spectra of the cell wall. Two-dimensional infrared spectroscopy was used to determine the nature of the interaction between the polysaccharide networks during deformation. The results provide evidence that cellulose and xyloglucan associate while pectin creates an independent network that exhibits different reorientation rates in the wet onion cell walls. The pectin chains respond faster to oscillation than the more rigid cellulose.
How Alfalfa Root Hairs Discriminate between Nod Factors and Oligochitin Elicitors
Authors: Felle Hubert H. , Kondorosi Éva , Kondorosi Ádam , Schultze Michael
Published: July 2002

Using ion-selective microelectrodes, the problem of how signals coming from symbiotic partners or from potential microbial intruders are distinguished was investigated on root hairs of alfalfa (Medicago sativa). The Nod factor, NodRm-IV(C16:2,S), was used to trigger the symbiotic signal and (GlcNAc)8 was selected from (GlcNAc)4-8, to elicit defense-related reactions. To both compounds, root hairs responded with initial transient depolarizations and alkalinizations, which were followed by a hyperpolarization and external acidification in the presence of (GlcNAc)8. We propose that alfalfa recognizes tetrameric Nod factors and N-acetylchitooligosaccharides (n = 4–8) with separate perception sites: (a) (GlcNAc)4 and (GlcNAc)6 reduced the depolarization response to (GlcNAc)8, but not to NodRm-IV(C16:2,S); and (b) depolarization and external alkalization were enhanced when NodRm-IV(C16:2,S) and (GlcNAc)8 were added jointly without preincubation. We suggest further that changes in cytosolic pH and Ca2+ are key events in the transduction, as well as in the discrimination of signals leading to symbiotic responses or defense-related reactions. To (GlcNAc)8, cells responded with a cytosolic acidification, and they responded to NodRm-IV(C16:2,S) with a sustained alkalinization. When both agents were added jointly, the cytosol first alkalized and then acidified. (GlcNAc)8 and NodRm-IV(C16:2,S) transiently increased cytosolic Ca2+ activity, whereby the response to (GlcNAc)8 exceeded the one to NodRm-IV(C16:2,S) by at least a factor of two.
The Effect of Exogenous Abscisic Acid on Stomatal Development, Stomatal Mechanics, and Leaf Gas Exchange inTradescantia virginiana
Authors: Franks Peter J. , Farquhar Graham D.
Published: July 2002

Gas exchange parameters and stomatal physical properties were measured in Tradescantia virginiana plants grown under well-watered conditions and treated daily with either distilled water (control) or 3.0 mm abscisic acid (ABA). Photosynthetic capacity (CO2 assimilation rate for any given leaf intercellular CO2 concentration [c  i]) and relative stomatal sensitivity to leaf-to-air vapor-pressure difference were unaffected by the ABA treatment. However, at an ambient CO2 concentration (c  a) of 350 μmol mol−1, ABA-treated plants operated with significantly lowerc  i. ABA-treated plants had significantly smaller stomata and higher stomatal density in their lower epidermis. Stomatal aperture versus guard cell pressure (P  g) characteristics measured with a cell pressure probe showed that although the form of the relationship was similar in control and ABA-treated plants, stomata of ABA-treated plants exhibited more complete closure atP  g = 0 MPa and less than half the aperture of stomata in control plants at any givenP  g. Scaling from stomatal aperture versusP  g to stomatal conductance versusP  g showed that plants grown under ABA treatment would have had significantly lower maximum stomatal conductance and would have operated with lower stomatal conductance for any given guard cell turgor. This is consistent with the observation of lower c  i/c  a in ABA-treated plants with a c  a of 350 μmol mol−1. It is proposed that the ABA-induced changes in stomatal mechanics and stomatal conductance versusP  g characteristics constitute an improvement in water-use efficiency that may be invoked under prolonged drought conditions.
Silencing on the Spot. Induction and Suppression of RNA Silencing in the Agrobacterium-Mediated Transient Expression System
Authors: Johansen Lisa K. , Carrington James C.
Published: July 2002

The Agrobacterium-mediated transient expression assay in intact tissues has emerged as a rapid and useful method to analyze genes and gene products in plants. In many cases, high levels of active protein can be produced without the need to produce transgenic plants. In this study, a series of tools were developed to enable strong or weak induction of RNA silencing and to suppress RNA silencing in the absence of stable transgenes. Transient delivery of a gene directing production of a double-stranded green fluorescent protein (GFP) transcript rapidly induced RNA silencing of a codelivered GFP reporter gene, effectively preventing accumulation of GFP protein and mRNA. RNA silencing triggered by the strong dsGFP inducer was partially inhibited by the tobacco etch virus silencing suppressor, P1/HC-Pro. In the absence of the strong double-stranded GFP inducer, the functional GFP gene served as a weak RNA silencing inducer in the transient assay, severely limiting accumulation of the GFP mRNA over time. The weak silencing induced by the GFP gene was suppressed by P1/HC-Pro. These results indicate RNA silencing can be triggered by a variety of inducers and analyzed entirely using transient gene delivery systems. They also indicate that RNA silencing may be a significant limitation to expression of genes in theAgrobacterium-mediated transient assay but that this limitation can be overcome by using RNA silencing suppressors.
The psychological contract, organisational commitment and job satisfaction of temporary staff
Authors: McDonald David J. , Makin Peter J.
Published: July 2002

The proportion of the workforce on temporary contracts of employment is increasing, as organisations use non‐permanent staff as a flexible resource. Rousseau and Wade‐Benzoni suggested such temporary staff have a different psychological contract with the organisation than their permanent counterparts. Temporary staff, it is argued, will have a transactional contract, with the emphasis upon the economic elements of the contract while permanent staff will have a more relational contract, involving commitment to the organisation, and an interest in a satisfying job. These differences, it is argued, will influence staff attitudes and behaviour. The article tests these suggestions on employees of a large holiday sector organisation. The results present a consistent picture, at variance with the above suggestions. The levels of relational and transactional contracts of permanent and temporary staff did not differ significantly. In addition they had higher, rather than lower, levels of job satisfaction and commitment to the organisation.
The learning organization: motivating employees by integrating TQM philosophy in a supportive organizational culture
Authors: Pool Steven W.
Published: July 2002

An organizational development model is developed to measure the constructs of a learning organization. A descriptive study was conducted investigating the relationships of total quality management, organizational culture and their impact upon a learning organization. The study investigated the attributes of a learning organization and its influence upon employee motivation. A total of 307 executives participated in the survey. The survey revealed that many executives had pursued professional development programs in TQM principles and/or in Senge’s organizational learning principles over the last four years. The executives completed a questionnaire measuring their perceptions involving the principles of a learning organization, TQM attributes, and their organizational culture. The results indicate a corporation implementing TQM principles in a supportive organizational culture has a positive and significant relationship with organizational learning compared to those executives not exposed to these constructs. Also, the findings revealed a positive and significant relationship between a learning organization and the motivational level of its business executives.
Team role balance and team performance: an empirical study
Authors: Partington David , Harris Hilary
Published: July 2002

Accompanying the growing use of teams in the workplace, Belbin’s diagnostic instrument for team role self‐perception is now widely used for a variety of practical management development purposes, including putting together “balanced” teams. Despite the claims of some purists that Belbin’s instrument lacks a strong theoretical underpinning, it fills an apparent void in practical teamworking literature, even though its applicability is not well understood. This study uses data from 43 teams of MBA students performing a project management simulation exercise, and finds no significant relationship between team role balance and team performance. Nevertheless, the study shows that the presence or absence of some individual roles can have a positive or negative effect on performance.
Intelligent building systems in Hong Kong offices
Authors: Chun To Cho Michael , Fellows Richard
Published: July 2002

This paper reports an investigation of the performance of a sample of office buildings in Hong Kong which were marketed as being intelligent. A summary review of literature charting the development of intelligent buildings and perspectives of what intelligence means when applied to office buildings provides a basis for the study. Adopting a fitness‐for‐purpose perspective, as the approach adopted most widely for evaluations, data on the buildings’ designs (incorporation of intelligence features), users’ requirements and occupants’ views of performance of their workplaces were collected via questionnaire surveys. Analysis followed the building ranking method adopted by Harrison. Results indicate that only a minority of the office buildings marketed as “intelligent” achieve the level of performance to match users’ and occupants’ requirements and so constitute business value intelligent buildings; the majority are underachieving.
Attitudes to building services component reuse in the UK healthcare sector
Authors: Thomson Derek S. , Kelly John R. , Webb Roy S.
Published: July 2002

Many organisations are responding to the diminishing stability of their operating environments by developing flexible methods of performing their core function. This creates demand for flexible supporting building space. While the architectural problems of providing such space have been solved for many years, its servicing remains problematic. This difficulty is manifested in the rising cost of services alterations necessitated when spaces are changed in use. The current inflexibility of services installation construction has prompted a study of reusable building services components. It is anticipated that this approach will increase services installation adaptability by reducing alteration costs. Focusing on the UK National Health Service, this paper presents a survey of trends in organisational function, their estate implications and the extent to which facilities managers can control or plan estate responses to frequent core function revision. Existing services component reuse practices are reviewed and component and process attributes conducive to disassembly and refurbishment are identified. It is concluded that, while reusable services components will achieve the required services installation adaptability, their technical feasibility and economic viability remain to be determined.
But is fire the issue …? The problems of managing multiple ownership buildings in Hong Kong
Authors: Walters Megan , Hastings E.M.
Published: July 2002

In common with many other cities in the world, Hong Kong has a large number of older and less well‐maintained buildings which, for predominantly economic reasons, are still highly utilised by a variety of mixed and non‐compatible uses. In these circumstances, a comprehensive approach to ensuring high standards of property management is essential, but recently a series of disastrous fires have highlighted some of the difficulties of managing property in this environment. The Government’s response to fire disasters has been to enact additional fire safety legislation. While the promotion of a safer environment in older buildings is to be applauded, it is arguable that such an approach merely addresses the symptoms ‐ the fires ‐ and not the underlying cause ‐ the management of such buildings. An examination of property management practice in Hong Kong indicates there are two important systemic factors which influence the standards and quality of services provided. The first is the way in which the property management industry is currently structured, the barriers to entry and the lack of regulation of property managers. The second is the way in which the responsibilities and relationships between owners and property managers are dictated by the method of ownership in multi‐ownership property. It is the impact that this method of ownership has on the twin issues of safety and property management which is examined in this paper.
Dynamic stability of elastically constrained beams: an exact approach
Authors: Majorana C.E. , Pellegrino C.
Published: July 2002

Finds the regions of dynamic instability of elastic beams constrained at the ends by means of translational and rotational elastic springs, using the equation of boundary frequencies. Obtains the diagrams showing the regions of instability of the beam, as a function of the dynamic component of the periodic forcing function and its frequency, from that equation in exact form. In this procedure inertial, stiffness and constraint characteristics of the examined system are taken into account. Presents selected applications concerning the analysed problem.
Parameter estimation for a viscoplastic damage model using a gradient‐based optimization algorithm
Authors: Mahnken Rolf , Johansson Magnus , Runesson Kenneth
Published: July 2002

In this work a gradient‐based optimization method is applied in order to determine material parameters for a viscoplastic model with dynamic yield surface coupled to damage as presented in 1997. To this end a sensitivity analysis consistent with the integration scheme presented previously is performed in a systematic manner, both for strain and stress controlled experiments. The algorithm is tested in two numerical examples: first, simulated data are used, in order to re‐obtain parameters for the case of damage under monotonic loading. In the second example material parameters are obtained based on experimental data for lcf‐testing of an austenetic stainless steel, thus showing a very good agreement with respect to hardening, rate and damage effects.
Is continuance commitment beneficial to organizations? Commitment‐performance relationship: a new look
Authors: Suliman Abubakr , Iles Paul
Published: July 2002

This paper explores the multifaceted nature of commitment in three industrial firms in Jordan. Furthermore, the study investigates the nature of organizational commitment using employees’ job performance and five demographic variables. The results confirm that organizational commitment is a three‐dimensional concept. The findings also uncover positive relationships between the global form of commitment and its three components on one hand, and job performance on the other hand. Moreover, organizational commitment and its three dimensions present positive and negative relationships with age, sex, education, job status, and organizational tenure variables. Implications for our understanding of the role of organizational commitment in the Middle East are also discussed.
Time management and polychronicity
Authors: Kaufman‐Scarborough Carol , Lindquist Jay D.
Published: July 2002

The goals of this investigation are to identify behaviors and attitudes that are predictive of an individual’s polychronic or monochronic time use, relating these findings to individuals’ time management approaches. A modified polychronic attitude indicator (PAI3) scale is used as the overall measure of monochronic/polychronic tendencies. A series of potential predictor variables from the “structure” portion of the FAST scale, items related to the time structure questionnaire, and other items based on literature synthesis and researcher judgment were used. A stepwise multiple regression analysis resulted in an eight‐predictor variable solution. It was concluded that polychronicity is related to different aspects of time management; recommendations are given for future study and for application in the workplace.
A new look at competent professional practice
Authors: Cheetham Graham , Chivers Geoff
Published: July 2002

Focuses on the nature of professional practice based on research conducted with practitioners via interviews and questionnaires. Aims to determine how practitioners actually tackle professional problem solving. Discusses reflection, specialised knowledge and repertoires of solutions, among other factors, and examines differences in professional practice according to age, gender and membership of various professions. Finds that although specialist knowledge is crucial to successful practice, improvisation is a key factor. Suggests that a combination of applied knowledge and reflection is important in professional practice.
Developing Directors:
Authors: Coulson‐Thomas Colin
Published: July 2002

Asks whether company boards are used to full effect in the light of the
growing responsibility on the shoulders of directors today. Highlights
the inadequate preparation provided for directors, considering the
substantial potential for their effectiveness. Outlines the processes
involved in building and maintaining a coherent, purposeful and
productive boardroom team, including the importance of defining
directorial competences. Punctuates throughout with comments by
experienced directors and suggested exercises for assessing directors′
training needs. Presents recommendations for how boardroom effectiveness
might be improved and maintained, providing key lessons and a business
excellence action plan.
The management of training in multinational corporations: comparative case studies
Authors: Noble Charles
Published: July 2002

Discusses the similarities and differences in the ways in which the training and development function is managed in multinational corporations (MNCs). Presents a comparative analysis (at three levels: international, industry and enterprise, with emphasis on enterprise) of enterprise‐based training in the UK and Australia, set in the context of the food and drink industry; and some of the government policies that affect the industry. Includes case studies of MNCs that operate in both countries, giving details of training strategies. Concludes that similarities in training and development strategies outweigh the differences; contrary to previous studies which draw attention to the differences between organizations and industries. Points out the relevance to managers and researchers who have an interest in the human resource management function in large organizations that operate across borders.
Strategies developed by US chemical firms to resolve their skill shortages
Authors: Besson Dominique , Haddadj Slimane
Published: July 2002

Today’s ever‐expanding global economy demands increased flexibility in all US industries where state‐of‐the‐art manufacturing and production methods are employed. A high‐skilled, well‐trained labor force is the key to a successful implementation of such methods that will allow the USA to compete effectively with those industrialized nations that have already made state‐of‐the‐art production and a high‐skilled labor force their top industrial and economic priorities. The US chemical industry, for example, is one industry that has found it quite difficult to follow through on these priorities. By factor analyses, regressions and cluster analyses, it is shown that many neo‐Taylorian practices persist through the development of lean production in this industry. If the US chemical industry is to compete competitively in the new global economy, it must make a more serious effort in addressing these priorities.
Calculation of eddy currents in moving structures using a finite element method on non‐matching grids
Authors: Rapetti F. , Santandrea L. , Bouillault F. , Razek A.
Published: July 2002

This paper deals with the numerical simulation of eddy current distributions in non‐stationary geometries with sliding interfaces. We study a system composed of two solid parts: a fixed one (stator) and a moving one (rotor) which slides in contact with the former. We also consider a two‐dimensional mathematical model based on the transverse electric formulation of the eddy current problem whose approximation is performed via the mortar element method combined with the standard linear finite element discretization in space and an implicit first order Euler scheme in time. Numerical results underline the influence of the rotor movement on the current distribution and give an estimate of the power losses with respect to the rotor angular speed.
The viable system model and the Viplan software
Authors: Espejo Raul , Bowling Diane , Hoverstadt Patrick
Published: July 2002

The software Viplan learning system is an aid to learn about Beer’s viable system model (VSM) and its application. This is done with the support of the Viplan method. The five activities of this method are explained with examples. First, it offers an approach to understand and discuss organisational identity through analysis of stakeholders. Second, it describes structural modelling of activities, which is followed by the crucial idea in the method of unfolding the organisation’s complexity. Fourth, it shows a tool for studying the distribution of resources and discretion in an organisation. Fifth, and finally, it offers a form of relating these resources to the VSM, thus allowing the development of diagnostic points. The paper ends with a short description of the software itself.