bluuebunny/crossref_metadata_2025 huggingface dataset:
The Two Genes Encoding Starch-Branching Enzymes IIa and IIb Are Differentially Expressed in Barley1
Authors: Sun Chuanxin , Sathish Puthigae , Ahlandsberg Staffan , Jansson Christer
Published: July 2002

The sbeIIa andsbeIIb genes, encoding starch-branching enzyme (SBE) IIa and SBEIIb in barley (Hordeum vulgare L.), have been isolated. The 5′ portions of the two genes are strongly divergent, primarily due to the 2064-nucleotide-long intron 2 insbeIIb. The sequence of this intron shows that it contains a retro-transposon-like element. Expression ofsbeIIb but not sbeIIa was found to be endosperm specific. The temporal expression patterns forsbeIIa and sbeIIb were similar and peaked around 12 d after pollination. DNA gel-blot analysis demonstrated that sbeIIa and sbeIIb are both single-copy genes in the barley genome. By fluorescence in situ hybridization, the sbeIIa and sbeIIbgenes were mapped to chromosomes 2 and 5, respectively. The cDNA clones for SBEIIa and SBEIIb were isolated and sequenced. The amino acid sequences of SBEIIa and SBEIIb were almost 80% identical. The major structural difference between the two enzymes was the presence of a 94-amino acid N-terminal extension in the SBEIIb precursor. The (β/α)8-barrel topology of the α-amylase superfamily and the catalytic residues implicated in branching enzymes are conserved in both barley enzymes.
Expression Studies of the Zeaxanthin Epoxidase Gene inNicotiana plumbaginifolia
Authors: Audran Corinne , Borel Charlotte , Frey Anne , Sotta Bruno , Meyer Christian , Simonneau Thierry , Marion-Poll Annie
Published: July 2002

Abscisic acid (ABA) is a plant hormone involved in the control of a wide range of physiological processes, including adaptation to environmental stress and seed development. In higher plants ABA is a breakdown product of xanthophyll carotenoids (C40) via the C15 intermediate xanthoxin. The ABA2 gene of Nicotiana plumbaginifolia encodes zeaxanthin epoxidase, which catalyzes the conversion of zeaxanthin to violaxanthin. In this study we analyzed steady-state levels of ABA2 mRNA in N. plumbaginifolia. The ABA2 mRNA accumulated in all plant organs, but transcript levels were found to be higher in aerial parts (stems and leaves) than in roots and seeds. In leavesABA2 mRNA accumulation displayed a day/night cycle; however, the ABA2 protein level remained constant. In roots no diurnal fluctuation in mRNA levels was observed. In seeds theABA2 mRNA level peaked around the middle of development, when ABA content has been shown to increase in many species. In conditions of drought stress, ABA levels increased in both leaves and roots. A concomitant accumulation of ABA2 mRNA was observed in roots but not in leaves. These results are discussed in relation to the role of zeaxanthin epoxidase both in the xanthophyll cycle and in the synthesis of ABA precursors.
NPH4, a Conditional Modulator of Auxin-Dependent Differential Growth Responses in Arabidopsis
Authors: Stowe-Evans Emily L. , Harper Reneé M. , Motchoulski Andrei V. , Liscum Emmanuel
Published: July 2002

Although sessile in nature, plants are able to use a number of mechanisms to modify their morphology in response to changing environmental conditions. Differential growth is one such mechanism. Despite its importance in plant development, little is known about the molecular events regulating the establishment of differential growth. Here we report analyses of the nph4(nonphototropic hypocotyl) mutants of Arabidopsis that suggest that the NPH4 protein plays a central role in the modulation of auxin-dependent differential growth. Results from physiological studies demonstrate that NPH4 activity is conditionally required for a number of differential growth responses, including phototropism, gravitropism, phytochrome-dependent hypocotyl curvature, apical hook maintenance, and abaxial/adaxial leaf-blade expansion. The nph4 mutants exhibited auxin resistance and severely impaired auxin-dependent gene expression, indicating that the defects associated with differential growth likely arise because of altered auxin responsiveness. Moreover, the auxin signaling events mediating phototropism are genetically correlated with the abundance of the NPH4 protein.
Changes in Hexokinase Activity inEchinochloa phyllopogon and Echinochloa crus-pavonis in Response to Abiotic Stress
Authors: Fox Theodore C. , Green Brian J. , Kennedy Robert A. , Rumpho Mary E.
Published: July 2002

Hexokinase (HXK; EC 2.7.1.1) regulates carbohydrate entry into glycolysis and is known to be a sensor for sugar-responsive gene expression. The effect of abiotic stresses on HXK activity was determined in seedlings of the flood-tolerant plant Echinochloa phyllopogon (Stev.) Koss and the flood-intolerant plant Echinochloa crus-pavonis (H.B.K.) Schult grown aerobically for 5 d before being subjected to anaerobic, chilling, heat, or salt stress. HXK activity was stimulated in shoots of E. phyllopogononly by anaerobic stress. HXK activity was only transiently elevated inE. crus-pavonis shoots during anaerobiosis. In roots of both species, anoxia and chilling stimulated HXK activity. Thus, HXK is not a general stress protein but is specifically induced by anoxia and chilling in E. phyllopogon and E. crus-pavonis. In both species HXK exhibited an optimum pH between 8.5 and 9.0, but the range was extended to pH 7.0 in air-grownE. phyllopogon to 6.5 in N2-grown E. phyllopogon. At physiologically relevant pHs (6.8 and 7.3, N2 and O2 conditions, respectively), N2-grown seedlings retained greater HXK activity at the lower pH. The pH response suggests that in N2-grown seedlings HXK can function in a more acidic environment and that a specific isozyme may be important for regulating glycolytic activity during anaerobic metabolism in E. phyllopogon.
Modification of Carbon Partitioning, Photosynthetic Capacity, and O2 Sensitivity in Arabidopsis Plants with Low ADP-Glucose Pyrophosphorylase Activity1
Authors: Sun Jindong , Okita Thomas W. , Edwards Gerald E.
Published: July 2002

Wild-type Arabidopsis plants, the starch-deficient mutant TL46, and the near-starchless mutant TL25 were evaluated by noninvasive in situ methods for their capacity for net CO2 assimilation, true rates of photosynthetic O2 evolution (determined from chlorophyll fluorescence measurements of photosystem II), partitioning of photosynthate into sucrose and starch, and plant growth. Compared with wild-type plants, the starch mutants showed reduced photosynthetic capacity, with the largest reduction occurring in mutant TL25 subjected to high light and increased CO2 partial pressure. The extent of stimulation of CO2 assimilation by increasing CO2 or by reducing O2 partial pressure was significantly less for the starch mutants than for wild-type plants. Under high light and moderate to high levels of CO2, the rates of CO2assimilation and O2 evolution and the percentage inhibition of photosynthesis by low O2 were higher for the wild type than for the mutants. The relative rates of14CO2 incorporation into starch under high light and high CO2 followed the patterns of photosynthetic capacity, with TL46 showing 31% to 40% of the starch-labeling rates of the wild type and TL25 showing less than 14% incorporation. Overall, there were significant correlations between the rates of starch synthesis and CO2 assimilation and between the rates of starch synthesis and cumulative leaf area. These results indicate that leaf starch plays an important role as a transient reserve, the synthesis of which can ameliorate any potential reduction in photosynthesis caused by feedback regulation.
A Computer-Assisted Personalized Approach in an Undergraduate Plant Physiology Class1
Authors: Artus Nancy N. , Nadler Kenneth D.
Published: July 2002

We used Computer-Assisted Personalized Approach (CAPA), a networked teaching and learning tool that generates computer individualized homework problem sets, in our large-enrollment introductory plant physiology course. We saw significant improvement in student examination performance with regular homework assignments, with CAPA being an effective and efficient substitute for hand-graded homework. Using CAPA, each student received a printed set of similar but individualized problems of a conceptual (qualitative) and/or quantitative nature with quality graphics. Because each set of problems is unique, students were encouraged to work together to clarify concepts but were required to do their own work for credit. Students could enter answers multiple times without penalty, and they were able to obtain immediate feedback and hints until the due date. These features increased student time on task, allowing higher course standards and student achievement in a diverse student population. CAPA handles routine tasks such as grading, recording, summarizing, and posting grades. In anonymous surveys, students indicated an overwhelming preference for homework in CAPA format, citing several features such as immediate feedback, multiple tries, and on-line accessibility as reasons for their preference. We wrote and used more than 170 problems on 17 topics in introductory plant physiology, cataloging them in a computer library for general access. Representative problems are compared and discussed.
A Selaginella lepidophyllaTrehalose-6-Phosphate Synthase Complements Growth and Stress-Tolerance Defects in a Yeasttps1Mutant1
Authors: Zentella Rodolfo , Mascorro-Gallardo José O. , Van Dijck Patrick , Folch-Mallol Jorge , Bonini Beatriz , Van Vaeck Christophe , Gaxiola Roberto , Covarrubias Alejandra A. , Nieto-Sotelo Jorge , Thevelein Johan M. , Iturriaga Gabriel
Published: July 2002

The accumulation of the disaccharide trehalose in anhydrobiotic organisms allows them to survive severe environmental stress. A plant cDNA,SlTPS1, encoding a 109-kD protein, was isolated from the resurrection plant Selaginella lepidophylla, which accumulates high levels of trehalose. Protein-sequence comparison showed that SlTPS1 shares high similarity to trehalose-6-phosphate synthase genes from prokaryotes and eukaryotes. SlTPS1mRNA was constitutively expressed in S. lepidophylla. DNA gel-blot analysis indicated that SlTPS1 is present as a single-copy gene. Transformation of a Saccharomyces cerevisiae tps1Δ mutant disrupted in theScTPS1 gene with S. lepidophylla SlTPS1restored growth on fermentable sugars and the synthesis of trehalose at high levels. Moreover, the SlTPS1 gene introduced into the tps1Δ mutant was able to complement both deficiencies: sensitivity to sublethal heat treatment at 39°C and induced thermotolerance at 50°C. The osmosensitive phenotype of the yeast tps1Δ mutant grown in NaCl and sorbitol was also restored by the SlTPS1 gene. Thus, SlTPS1 protein is a functional plant homolog capable of sustaining trehalose biosynthesis and could play a major role in stress tolerance in S. lepidophylla.
Starch and the Control of Kernel Number in Maize at Low Water Potentials
Authors: Zinselmeier Christopher , Jeong Byeong-Ryong , Boyer John S.
Published: July 2002

After reproduction is initiated in plants, subsequent reproductive development is sometimes interrupted, which decreases the final number of seeds and fruits. We subjected maize (Zea mays L.) to low water potentials (ψw) that frequently cause this kind of failure. We observed metabolite pools and enzyme activities in the developing ovaries while we manipulated the sugar stream by feeding sucrose (Suc) to the stems. Low ψw imposed for 5 d around pollination allowed embryos to form, but abortion occurred and kernel number decreased markedly. The ovary contained starch that nearly disappeared during this abortion. Analyses showed that all of the intermediates in starch synthesis were depleted. However, when labeled Suc was fed to the stems, label arrived at the ovaries. Solute accumulated and caused osmotic adjustment. Suc accumulated, but other intermediates did not, showing that a partial block in starch synthesis occurred at the first step in Suc utilization. This step was mediated by invertase, which had low activity. Because of the block, Suc feeding only partially prevented starch disappearance and abortion. These results indicate that young embryos abort when the sugar stream is interrupted sufficiently to deplete starch during early ovary development, and this abortion results in a loss of mature seeds and fruits. At low ψw, maintaining the sugar stream partially prevented the abortion, but invertase regulated the synthesis of ovary starch and partially prevented full recovery.
Chloroplast Acclimation in Leaves of Guzmania monostachia in Response to High Light
Authors: Maxwell Kate , Marrison Joanne L. , Leech Rachel M. , Griffiths Howard , Horton Peter
Published: July 2002

Acclimation of leaves to high light (HL; 650 μmol m−2 s−1) was investigated in the long-lived epiphytic bromeliad Guzmania monostachiaand compared with plants maintained under low light (LL; 50 μmol m−2 s−1). Despite a 60% decrease in total chlorophyll in HL-grown plants, the chlorophyll a/bratio remained stable. Additionally, chloroplasts from HL-grown plants had a much lower thylakoid content and reduced granal stacking. Immunofluorescent labeling techniques were used to quantify the level of photosynthetic polypeptides. HL-grown plants had 30% to 40% of the content observed in LL-grown plants for the light-harvesting complex associated with photosystems I and II, the 33-kD photosystem II polypeptide, and Rubisco. These results were verified using conventional biochemical techniques, which revealed a comparable 60% decrease in Rubisco and total soluble protein. When expressed on a chlorophyll basis, the amount of protein and Rubisco was constant for HL- and LL-grown plants. Acclimation to HL involves a tightly coordinated adjustment of photosynthesis, indicating a highly regulated decrease in the number of photosynthetic units manifested at the level of the content of light-harvesting and electron transport components, the amount of Rubisco, and the induction of Crassulacean acid metabolism. This response occurs in mature leaves and may represent a strategy that is optimal for the resource-limited epiphytic niche.
An Imperfect Heat Shock Element and Different Upstream Sequences Are Required for the Seed-Specific Expression of a Small Heat Shock Protein Gene
Authors: Carranco Raúl , Almoguera Concepción , Jordano Juan
Published: July 2002

Chimeric constructs containing the promoter and upstream sequences of Ha hsp17.6 G1, a small heat shock protein gene, reproduced in transgenic tobacco (Nicotiana tabacum) its unique seed-specific expression patterns previously reported in sunflower. These constructs did not respond to heat shock, but were expressed without exogenous stress during late zygotic embryogenesis coincident with seed desiccation. Site-directed mutagenesis of its distal and imperfect heat shock element strongly impaired in vitro heat shock transcription factor binding and transgene expression in seeds. Deletion analyses of upstream sequences indicated the contribution of additional cis-acting elements with either positive or negative effects on transgene expression. These results show differences in the transcriptional activation through the heat shock element of small heat shock protein gene promoters in seeds compared with the heat shock response. In addition, they suggest that heat shock transcription factors and other distinct trans-acting factors cooperate in the regulation of Ha hsp17.6 G1 during seed desiccation.
Cloning and Functional Characterization of a Constitutively Expressed Nitrate Transporter Gene,OsNRT1, from Rice
Authors: Lin Chung-Ming , Koh Serry , Stacey Gary , Yu Su-May , Lin Tsai-Yun , Tsay Yi-Fang
Published: July 2002

Elucidating how rice (Oryza sativa) takes up nitrate at the molecular level could help improve the low recovery rate (<50%) of nitrogen fertilizer in rice paddies. As a first step toward that goal, we have cloned a nitrate transporter gene from rice called OsNRT1. OsNRT1 is a new member of a growing transporter family called PTR, which consists not only of nitrate transporters from higher plants that are homologs of the Arabidopsis CHL1 (AtNRT1) protein, but also peptide transporters from a wide variety of genera including animals, plants, fungi, and bacteria. However, despite the fact that OsNRT1 shares a higher degree of sequence identity with the two peptide transporters from plants (approximately 50%) than with the nitrate transporters (approximately 40%) of the PTR family, no peptide transport activity was observed when OsNRT1 was expressed in either Xenopus oocytes or yeast. Furthermore, contrasting the dual-affinity nitrate transport activity of CHL1, OsNRT1 displayed only low-affinity nitrate transport activity in Xenopus oocytes, with aK  m value of approximately 9 mm. Northern-blot and in situ hybridization analysis indicated that OsNRT1 is constitutively expressed in the most external layer of the root, epidermis and root hair. These data strongly indicate thatOsNRT1 encodes a constitutive component of a low-affinity nitrate uptake system for rice.
Calcium-Calmodulin Suppresses the Filamentous Actin-Binding Activity of a 135-Kilodalton Actin-Bundling Protein Isolated from Lily Pollen Tubes
Authors: Yokota Etsuo , Muto Shoshi , Shimmen Teruo
Published: July 2002

We have isolated a 135-kD actin-bundling protein (P-135-ABP) from lily (Lilium longiflorum) pollen tubes and have shown that this protein is responsible for bundling actin filaments in lily pollen tubes (E. Yokota, K. Takahara, T. Shimmen [1998] Plant Physiol 116: 1421–1429). However, only a few thin actin-filament bundles are present in random orientation in the tip region of pollen tubes, where high concentrations of Ca2+ have also been found. To elucidate the molecular mechanism for the temporal and spatial regulation of actin-filament organization in the tip region of pollen tubes, we explored the possible presence of factors modulating the filamentous actin (F-actin)-binding activity of P-135-ABP. The F-actin-binding activity of P-135-ABP in vitro was appreciably reduced by Ca2+ and calmodulin (CaM), although neither Ca2+ alone nor CaM in the presence of low concentrations of Ca2+ affects the activity of P-135-ABP. A micromolar order of Ca2+ and CaM were needed to induce the inhibition of the binding activity of P-135-ABP to F-actin. An antagonist for CaM, W-7, cancelled this inhibition. W-5 also alleviated the inhibition effect of Ca2+-CaM, however, more weakly than W-7. These results suggest the specific interaction of P-135-ABP with Ca2+-CaM. In the presence of both Ca2+ and CaM, P-135-ABP organized F-actin into thin bundles, instead of the thick bundles observed in the absence of CaM. These results suggest that the inhibition of the P-135-ABP activity by Ca2+-CaM is an important regulatory mechanism for organizing actin filaments in the tip region of lily pollen tubes.
Subcellular Localization of a High Affinity Binding Site ford-myo-Inositol 1,4,5-Trisphosphate fromChenopodium rubrum
Authors: Martinec Jan , Feltl Tomáš , Scanlon Chris H. , Lumsden Peter J. , Macháčková Ivana
Published: July 2002

It is now generally accepted that a phosphoinositide cycle is involved in the transduction of a variety of signals in plant cells. In animal cells, the binding of d-myo-inositol 1,4,5-trisphosphate (InsP3) to a receptor located on the endoplasmic reticulum (ER) triggers an efflux of calcium release from the ER. Sites that bind InsP3 with high affinity and specificity have also been described in plant cells, but their precise intracellular locations have not been conclusively identified. In contrast to animal cells, it has been suggested that in plants the vacuole is the major intracellular store of calcium involved in signal induced calcium release. The aim of this work was to determine the intracellular localization of InsP3-binding sites obtained from 3-week-old Chenopodium rubrum leaves. Microsomal membranes were fractionated by sucrose density gradient centrifugation in the presence and absence of Mg2+ and alternatively by free-flow electrophoresis. An ER-enriched fraction was also prepared. The following enzymes were employed as specific membrane markers: antimycin A-insensitive NADH-cytochrome c reductase for ER, cytochrome c oxidase for mitochondrial membrane, pyrophosphatase for tonoplast, and 1,3-β-d-glucansynthase for plasma membrane. In all membrane separations, InsP3-binding sites were concentrated in the fractions that were enriched with ER membranes. These data clearly demonstrate that the previously characterized InsP3-binding site from C. rubrum is localized on the ER. This finding supports previous suggestions of an alternative non-vacuolar InsP3-sensitive calcium store in plant cells.
Redox-Regulated RNA Helicase Expression
Authors: Kujat Sonya L. , Owttrim George W.
Published: July 2002

In photosynthetic organisms it is becoming increasingly evident that light-driven shifts in redox potential act as a sensor that initiates alterations in gene expression at both the level of transcription and translation. This report provides evidence that the expression of a cyanobacterial RNA helicase gene,crhR, is controlled at the level of transcription and mRNA stability by a complex series of interacting mechanisms that are redox regulated. Transcript accumulation correlates with reduction of the electron transport chain between QA in photosystem II and QO in cytb  6  f, whenSynechocystis sp. strain PCC 6803 is cultured photoautotrophically or photomixotrophically and subjected to darkness and/or electron transport inhibitors or illumination that preferentially excites photosystem II. crhR mRNA stability is also regulated by a redox responsive mechanism, which differs from that affecting accumulation and does not involve signaling initiated by photoreceptors. The data are most consistent with plastoquinol/cyt b  6  finteraction as the sensor initiating a signal transduction cascade resulting in accumulation of the crhR transcript. Functionally, CrhR RNA unwinding could act as a linker between redox regulated transcription and translation. The potential for translational regulation of redox-induced gene expression through RNA helicase-catalyzed modulation of RNA secondary structure is discussed.
Quantitative Trait Loci for Component Physiological Traits Determining Salt Tolerance in Rice
Authors: Koyama Mikiko L. , Levesley Aurora , Koebner Robert M.D. , Flowers Timothy J. , Yeo Anthony R.
Published: July 2002

Rice (Oryza sativa) is sensitive to salinity, which affects one-fifth of irrigated land worldwide. Reducing sodium and chloride uptake into rice while maintaining potassium uptake are characteristics that would aid growth under saline conditions. We describe genetic determinants of the net quantity of ions transported to the shoot, clearly distinguishing between quantitative trait loci (QTL) for the quantity of ions in a shoot and for those that affect the concentration of an ion in the shoot. The latter coincide with QTL for vegetative growth (vigor) and their interpretation is therefore ambiguous. We distinguished those QTL that are independent of vigor and thus directly indicate quantitative variation in the underlying mechanisms of ion uptake. These QTL independently govern sodium uptake, potassium uptake, and sodium:potassium selectivity. The QTL for sodium and potassium uptake are on different linkage groups (chromosomes). This is consistent with the independent inheritance of sodium and potassium uptake in the mapping population and with the mechanistically different uptake pathways for sodium and potassium in rice under saline conditions (apoplastic leakage and membrane transport, respectively). We report the chromosomal location of ion transport and selectivity traits that are compatible with agronomic needs and we indicate markers to assist selection in a breeding program. Based upon knowledge of the underlying mechanisms of ion uptake in rice, we argue that QTL for sodium transport are likely to act through the control of root development, whereas QTL for potassium uptake are likely to act through the structure or regulation of membrane-sited transport components.
Increased Sensitivity of Photosynthesis to Antimycin A Induced by Inactivation of the Chloroplast ndhB Gene. Evidence for a Participation of the NADH-Dehydrogenase Complex to Cyclic Electron Flow around Photosystem I
Authors: Joët Thierry , Cournac Laurent , Horvath Eva M. , Medgyesy Peter , Peltier Gilles
Published: July 2002

Tobacco (Nicotiana tabacum var Petit Havana)ndhB-inactivated mutants (ndhB  −) obtained by plastid transformation (E.M. Horvath, S.O. Peter, T. Joët, D. Rumeau, L. Cournac, G.V. Horvath, T.A. Kavanagh, C. Schäfer, G. Peltier, P. MedgyesyHorvath [2000] Plant Physiol 123: 1337–1350) were used to study the role of the NADH-dehydrogenase complex (NDH) during photosynthesis and particularly the involvement of this complex in cyclic electron flow around photosystem I (PSI). Photosynthetic activity was determined on leaf discs by measuring CO2exchange and chlorophyll fluorescence quenchings during a dark-to-light transition. In the absence of treatment, both non-photochemical and photochemical fluorescence quenchings were similar inndhB  − and wild type (WT). When leaf discs were treated with 5 μm antimycin A, an inhibitor of cyclic electron flow around PSI, both quenchings were strongly affected. At steady state, maximum photosynthetic electron transport activity was inhibited by 20% in WT and by 50% inndhB  −. Under non-photorespiratory conditions (2% O2, 2,500 μL L−1CO2), antimycin A had no effect on photosynthetic activity of WT, whereas a 30% inhibition was observed both on quantum yield of photosynthesis assayed by chlorophyll fluorescence and on CO2 assimilation in ndhB  −. The effect of antimycin A on ndhB  − could not be mimicked by myxothiazol, an inhibitor of the mitochondrial cytochromebc  1 complex, therefore showing that it is not related to an inhibition of the mitochondrial electron transport chain but rather to an inhibition of cyclic electron flow around PSI. We conclude to the existence of two different pathways of cyclic electron flow operating around PSI in higher plant chloroplasts. One of these pathways, sensitive to antimycin A, probably involves ferredoxin plastoquinone reductase, whereas the other involves the NDH complex. The absence of visible phenotype in ndhB  −plants under normal conditions is explained by the complement of these two pathways in the supply of extra-ATP for photosynthesis.
Long-Distance Signaling and the Control of Branching in therms1 Mutant of Pea
Authors: Foo Eloise , Turnbull Colin G.N. , Beveridge Christine A.
Published: July 2002

The ramosus (rms) mutation (rms1) of pea (Pisum sativum) causes increased branching through modification of graft-transmissible signal(s) produced in rootstock and shoot. Additional grafting techniques have led us to propose that the novel signal regulated byRms1 moves acropetally in shoots and acts as a branching inhibitor. Epicotyl interstock grafts showed that wild-type (WT) epicotyls grafted between rms1 scions and rootstocks can revert mutant scions to a WT non-branching phenotype. Mutant scions grafted together with mutant and WT rootstocks did not branch despite a contiguous mutant root-shoot system. The primary action ofRms1 is, therefore, unlikely to be to block transport of a branching stimulus from root to shoot. Rather, Rms1may influence a long-distance signal that functions, directly or indirectly, as a branching inhibitor. It can be deduced that this signal moves acropetally in shoots because WT rootstocks inhibit branching in rms1 shoots, and although WT scions do not branch when grafted to mutant rootstocks, they do not inhibit branching in rms1 cotyledonary shoots growing from the same rootstocks. The acropetal direction of transport of theRms1 signal supports previous evidence that therms1 lesion is not in an auxin biosynthesis or transport pathway. The different branching phenotypes of WT andrms1 shoots growing from the same rms1rootstock provides further evidence that the shoot has a major role in the regulation of branching and, moreover, that root-exported cytokinin is not the only graft-transmissible signal regulating branching in intact pea plants.
Targeting a Nuclear Anthranilate Synthase α-Subunit Gene to the Tobacco Plastid Genome Results in Enhanced Tryptophan Biosynthesis. Return of a Gene to Its Pre-Endosymbiotic Origin
Authors: Zhang Xing-Hai , Brotherton Jeffrey E. , Widholm Jack M. , Portis Archie R.
Published: July 2002

Anthranilate synthase (AS), the control enzyme of the tryptophan (Trp) biosynthetic pathway, is encoded by nuclear genes, but is transported into the plastids. A tobacco (Nicotiana tabacum) cDNA (ASA2) encoding a feedback-insensitive tobacco AS α-subunit was transformed into two different sites of the tobacco plastid genome through site-specific insertion to obtain transplastomic plants with normal phenotype and fertility. A high and uniform level of ASA2 mRNA was observed in the transplastomic plants but not in the wild type. Although the plants with the transgene insertion atndhF-trnL only expressed one size of theASA2 mRNA, the plants with the transgene incorporated into the region between accD and open reading frame (ORF) 184 exhibited two species of mRNA, apparently due to readthrough. The transplastomic plants exhibited a higher level of AS α-subunit protein and AS enzyme activity that was less sensitive to Trp-feedback inhibition, leading to greatly increased free Trp levels in leaves and total Trp levels in seeds. Resistance to an AS inhibitor, 5-methyl-Trp, was found during seed germination and in suspension cultures of the transplastomic plants. The resistance to the selection agent spectinomycin and to 5-methyl-Trp was transmitted maternally. These results demonstrate the feasibility of modifying the biosynthetic pathways of important metabolites through transformation of the plastid genome by relocating a native gene from the nucleus to the plastid genome. Very high and uniform levels of gene expression can be observed in different lines, probably due to the identical insertion sites, in contrast to nuclear transformation where random insertions occur.
From robust control to antiwindup compensation of electrohydraulic servo actuators
Authors: Ursu I. , Tecuceanu G. , Ursu F. , Sireteanu T. , Vladimirescu M.
Published: July 2002

A method of designing the controller to solve the robust servomechanism problem is applied in the case of an electrohydraulic servo actuating primary flight control. This method is based on the well‐known solution consisting of two separate devices: a servocompensator, in fact an internal model of the exogenous dynamics, including the reference commands and disturbance signals; and a stabilizing compensator. The proof is made involving the servocompensator structure which is close to the one designed for step signals. The stabilizing compensator is assured by way of a linear quadratic optimal procedure. An antiwindup compensation is added to deal with the adverse effects caused by actuator saturation.
The weight of aircraft
Authors: Barlow Major T.M.
Published: July 2002

This was selected as an excellent example of one of the papers published in the first ever issue of Aircraft Engineering in March 1929. It was presented at the Royal Aeronautical Society on 22 November 1928 and then published in the journal. It discusses the characteristics and influences affecting aircraft weight, and possible developments with increasing size and therefore provides a fascinating reminder of technology and thinking in the late 1920s.
Inhibition effect of ethanolamines on oil well tubular material in hydrochloric acid
Authors: Jayaperumal D. , Muralidharan S. , Venkatachari G. , Rengaswamy N.S.
Published: July 2002

Acidization is one of the most important techniques to increase the productivity of crude petroleum oil and gas wells. The effective way for protecting these oil well tubular materials is by using corrosion inhibitors during the acidization process. The present study deals with the evaluation of inhibition effect of ethanolamines on oil well tubular materials of grade N‐80 steel in 15 per cent hydrochloric acid at room temperature with 0‐2 per cent amine concentrations. The amines such as mono, di and triethanolamine were studied for their inhibiting capacity by mass loss method, DC polarization method and AC Impedance method. The inhibitor efficiency increases with increasing concentration of amines. Monoethanolamine is found to be more effective than the other two amines.
Corrosion performance of 316L SS and titanium modified austenitic stainless steels in the bleaching stages
Authors: Suresh Kumar Danadurai K. , Rajeswari S.
Published: July 2002

The present study aims to evaluate the performance of titanium modified austenitic stainless steels in the simulated bleaching stages, viz. washer stage, peroxide and hyprochlorite stages. Potentiodynamic anodic cyclic polarization method was adopted to determine the critical parameters such as corrosion potential, breakdown potential and pit‐protection potential.
The healthy option
Authors: Bowker Sue , Crosswaite Catriona , Hickman Mary , McGuffin Sam , Tudor‐Smith Chris
Published: July 2002

The UK has been participating in the European Network of Health Promoting Schools (ENHPS) since 1993. One of the main concerns identified by participating schools has been the provision of food on their premises. This paper looks at some of the ways the ENHPS project schools have moved towards developing a whole school approach to food and nutrition. Key themes identified by the schools include: linking the school curriculum with the school dining room and other food outlets; involving pupils and parents; improving the design and environment of the school dining room; and collaborating with the school’s catering service. Argues that, through such initiatives, schools have the potential to make a significant contribution to dietary change and the health of their pupils.
Why IT Applications Succeed or Fail
Authors: Cannon James A.
Published: July 2002

Reports on the reasons for failure in IT applications. Looks at typical
cases of failure and defines success factors. Concludes that a range of
human and technical factors interplay together, to produce project
failure. Offers general guidance for project success, with emphasis on
management and management style.
Training needs analysis for IT training
Authors: Eighteen Robert
Published: July 2002

Without appropriately educating staff about new technologies and what they can do for them, businesses will go on incurring the cost of software implementation without exploiting the benefits. Tailored training solutions are almost universally offered these days, but do companies really know what they are getting? What do we mean by “tailored training” anyway? How is the content of the training determined and will it suit each of those to be trained? Key Training have pioneered the creation and development of an automated Training Needs Analysis (TNA 2000) a tool used to establish the organisational, departmental and individual objectives of those to be trained.
Automatic thesaurus for enhanced Chinese text retrieval
Authors: Foo Schubert , Cheung Hui Siu , Koon Lim Hong , Hui Li
Published: July 2002

Asian languages such as Japanese, Korean and in particular Chinese, are beginning to gain popularity in the information retrieval (IR) domain. The quality of IR systems has traditionally been judged by the system’s retrieval effectiveness which, in turn, is commonly measured by data recall and data precision. This paper proposes and describes a process for generating an automatic Chinese thesaurus that can be used to provide related terms to a user’s queries to enhance retrieval effectiveness. In the absence of existing automatic Chinese thesauri, techniques used in English thesaurus generation have been evaluated and adapted to generate a Chinese equivalent. The automatic thesaurus is generated by computing the co‐occurrence values between domain‐specific terms found in a document collection. These co‐occurrence values are in turn derived from the term and document frequencies of the terms. A set of experiments was subsequently carried out on a document test set to evaluate the applicability of the thesaurus. Results obtained from these experiments confirmed that such an automatic generated thesaurus is able to improve the retrieval effectiveness of a Chinese IR system.
Information policy for a new millennium
Authors: Law Derek
Published: July 2002

Previous revolutions, the Agrarian and Industrial, are examined and their features compared with the Information Revolution. Lessons are drawn from the comparison and a range of global issues identified. The nature of the Internet is considered and its pretensions argued to be inflated. The role of the state in developing an information society is discussed. A national information policy is identified as a feature and its application in and implications for Scotland are considered. Key features of an Internet culture are indicated and discussed, with lessons and conclusions for social development within the information society presented.
Praise the Net and pass the modem: revolutionaries and captives in the information society
Authors: Haywood Trevor
Published: July 2002

Poses the question: in envisaging a digitally networked future, what kind of graffiti can we discern on the emerging cyberwall to help us predict its likely impact on large populations? All evaluation of infant technologies is a complex business. Technology gives and it takes away. Science transforms human behaviour but we want it to be subject to the scrutiny of independent moral principles, which themselves shift. Argues that the long‐term advantages or disadvantages that will spin off from the electronic flow and rush of information will grow out of the wider, messier social, political and economic imperatives of the future world within which networking will reside. Electronic communication along networks operates on many levels: it is heavily diffused throughout the rest of the technical pantheon. Its exacerbation of the already discernible drift towards social isolation and alienation and its role in facilitating the economic and social rejuvenation of large, as opposed to élite, populations seem more questionable.
Understanding library‐anxious graduate students
Authors: Onwuegbuzie Anthony J. , Jiao Qun G.
Published: July 2002

Research suggests that learning preference is an antecedent of statistics anxiety and research anxiety experienced by graduate students. Thus, the purpose of this study was to investigate the relationship between learning preferences and the following antecedents of library anxiety: “barriers with staff”, “affective barriers”, “comfort with the library”, “knowledge of the library”, and “mechanical barriers” among graduate students. Participants were 203 graduate students enrolled in a research methodology course. A series of setwise regression analyses revealed that the following 13 learning environmental preferences were related to one or more of these antecedents: noise preference, persistence orientation, responsibility, structure, peer orientation, authority orientation, multiple perceptual orientation, visual orientation, tactile orientation, kinesthetic orientation, morning preference, afternoon preference, and mobility preference. The implications of these findings are discussed.
MAFF’s food acceptability and choice research programme: an introduction
Authors: Woolfe Jennifer A.
Published: July 2002

Outlines the Ministry of Agriculture, Fisheries and Food’s food acceptability and choice programme. Established in 1991 the programme’s main aim was to improve the nation’s health through improved nutrition and health by promoting dietary change. Twenty‐four separate research projects have so far been commissioned, 17 of which have been completed. Lists the broad topics of the research and briefly outlines the future plans.
The role of traditional cereal/legume/fruit‐based multimixes in weaning in developing countries
Authors: Amuna Paul , Zotor Francis , Sumar Sam , Tswelelo Chinyanga Yvonne
Published: July 2002

The weaning period is a crucial stage in the growth and development of the infant and child. The timing of weaning, the choice of foods, their methods of preparation, and how weanlings are fed, all affect the outcome. The commercial preparation of weaning foods and the fortification of some traditional foods are seen by some as the most sustainable and cost‐effective means of alleviating micronutrient deficiencies among infants and children. This may be true in industrialized countries, but the same cannot necessarily be said of poor, developing countries. Demonstrates that, even in poor communities, it is possible to combine scant food resources in a cost‐effective way to formulate multimixes which would meet energy, protein and micronutrient needs, without fortification. Proposes that such approaches can be used in community nutrition education programmes to help reduce childhood malnutrition and in emergency feeding programmes.
Metabolic interactions between zinc and essential fatty acids in the mammalian organism
Authors: Adisa Akinola O. , Odutuga Adewale A.
Published: July 2002

Zinc and essential fatty acid deficiencies manifest similar syndromes provoking investigations into the mechanisms underlying their metabolic interactions. This article presents a lucid and concise review of literature on the possible connection between these important dietary nutrients as exemplified by the role of zinc in modulating intestinal lipid transport and prostaglandins metabolisms as well as maintenance of membrane structural and functional integrity. Reports of investigations on zinc and essential fatty acid deficiencies, regarding their pleitropic effects on clinically important enzymes, from the laboratory of the authors were also considered.
The graduate management trainee preselection interview
Authors: Papadopoulou Androniki , Ineson Elizabeth , Williams David
Published: July 2002

Describes a study which aimed to capture the candidates’ perceptions of a graduate employment interview, in particular how the interviewer’s manner and ability may affect interview outcomes. Eighty‐seven questionnaires were received from graduate candidates immediately after their interviews with an international retailing company based in the UK. Factor analysis produced five factors relating to “interpersonal manner” and two relating to “ability to communicate”. Outlines the findings which were that: the impact made by the interviewer was a function of his/her professional style rather than his/her empathetic behaviour; the degree of empathy shown by the interviewer affected the interviewees’ perceptions of the interviewer’s competence as a supplier of information; and overall satisfaction with the interview was a function of the empathetic behaviour of the interviewer. Discusses the findings in the framework of the “signalling hypothesis” and other communication literature.
Ageism in work and employment: thinking about connections
Authors: Branine Mohamed , Glover Ian
Published: July 2002

Emphasizes the universality, variety and scope of ageism. Considers why systematic investigation of the phenomenon has begun in recent years and how it has become a subject of political argument and debate. Suggests how thinking about ageism should be linked to the study of many economic, social and political factors. Argues that two contrasting theories, commodification and greening, may be useful in exploring the ways in which ageism influences and is influenced by the unfolding development of contemporary advanced, and many developing, societies.
The poverty of empowerment? A critical case study
Authors: Cunningham Ian , Hyman Jeff
Published: July 2002

The paper presents findings from a case study organisation which has ostensibly adopted an empowerment programme. The findings indicate a rather different trajectory for empowerment than anticipated by most prescriptive accounts. Both employees and their empowered managers expressed high levels of discontent with the programme and its effects. Little sign of increased commitment was evident after the introduction of the initiative and management controls seemed to have tightened rather than loosened. The apparent failure of the empowerment initiative to raise morale and commitment is attributed to lack of resources allocated to the project, lack of management preparation; an unsympathetic cultural context; supremacy of operational issues, and weakened presence and authority. The paper concludes that empowerment projects are unlikely to engage the commitment of employees without addressing the major shortcomings identified above. Nevertheless, resultant work intensification might lead to increased physical productivity.
Global change, economic restructuring and labour market issues in Mexico City
Authors: Jimenez Miguel
Published: July 2002

This paper analyses how economic effects driven by the process of globalization, such as those generated by the rise in international trade and in flows of foreign direct investment, have modified the local economy and in particular, job structures. The case of Mexico City is used in order to explore the effect of these economic activities on the labour markets of the manufacturing and service sectors.
Autonomous industrial robots and task path modelling theory
Authors: Moore David R.
Published: July 2002

A discouraging problem regarding the use of robots within production processes is the perception by designers of single, unique products (such as buildings) that a manufacturing approach, reliant upon high levels of standardisation, constrains design creativity. An alternative approach, based upon the production philosophy of true simplification, is proposed. This suggests that robots be provided with an ability to reason founded in Task Path modelling theory, enabling them to autonomously carry out task planning within the context of the production problem, and path planning within the production environment. These actions are combined as the basis of task path theory. Task path theory does not infer that robots attempt to emulate human operatives in their physical actions with regard to the production process.
Robotic applications for hot‐line maintenance
Authors: Maruyama Yoshinaga
Published: July 2002

Since 1984, Kyushu Electric Power Company (KYUDEN) has made all‐out efforts to introduce outage‐free maintenance techniques. Robotic techniques are promoted as part of these efforts. Although the final objective is to develop a fully‐automatic hot‐line work robot, there are three steps in the technological development. The first step was the development of the bucket operation type manipulator Phase I, which was completed in 1989. Phase II, the second step in KYUDEN’s robot development, is one of semi‐automatic operation, with the operator assisting via remote control from a cabin on the ground. Tasks are conducted automatically, with the operator providing judgement and commands for each unit‐task. Development of Phase II was completed in December 1997. A field test of 17 Phase II units started at the end of 1999 following testing and operation training. This paper will present an outline of this robot system.
The Amadeus project: an overview
Authors: Robinson G. , Davies J.B.C.
Published: July 2002

Looks at Amadeus (advanced manipulator for deep underwater systems) which is an international subsea manipulator project, funded by the European Community Marine Science and Technology Research Programme. The object is to improve the sampling and manipulation capabilities of underwater systems, through the development of advanced grippers and manipulation control techniques. Says that Phase 1 of the project produced an innovative dextrous gripper system for laboratory use. The objective of phase 2 is to produce more robust systems offering enhanced functionality and suitability for trials in the marine environment. Provides an overview of the Amadeus project describing the achievements of the first phase and the proposed developments for phase 2.