bluuebunny/crossref_metadata_2025 huggingface dataset:
Cloning and Overexpression of Two cDNAs Encoding the Low-CO2-lnducible Chloroplast Envelope Protein LIP-36 from Chlamydomonas reinhardtii
Authors: Chen Z. Y. , Lavigne L. L. , Mason C. B. , Moroney J. V.
Published: July 2002

Chlamydomonas reinhardtii, a unicellular green alga, grows photoautotrophically at very low concentrations of inorganic carbon due to the presence of an inducible CO2-concentrating mechanism. During the induction of the CO2-concentrating mechanism at low-CO2 growth conditions, at least five polypeptides that are either absent or present in low amounts in cells grown on high-CO2 concentrations are induced. One of these induced polypeptides with a molecular mass of 36 kD, LIP-36, has been localized to the chloroplast envelope. The protein was purified and the partial internal amino acid sequences were obtained through lys-C digestion. Two cDNAs encoding LIP-36 have been cloned using degenerate primers based on the amino acid sequences. The two genes encoding LIP-36 are highly homologous in the coding region but are completely different in the 5[prime]-end and 3[prime]-end untranslated regions. The deduced protein sequences show strong homology to the mitochondrial carrier protein superfamily, suggesting that LIP-36 is a chloroplast carrier protein. The regulation of the expression of these two genes at high- and low-CO2 growth conditions is also different. Both genes were highly expressed under low-CO2 growth conditions, with the steady-state level of LIP-36 G1 mRNA more abundant. However, neither gene was expressed at high-CO2 growth conditions. The gene products of both clones expressed in Escherichia coli were recognized by an antibody raised against LIP-36, confirming that the two cDNAs indeed encode the C. reinhardtii chloroplast envelope carrier protein LIP-36.
Acidic Phosphoprotein Complex of the 60S Ribosomal Subunit of Maize Seedling Roots (Components and Changes in Response to Flooding)
Authors: Bailey-Serres J. , Vangala S. , Szick K. , Lee CHK.
Published: July 2002

We determined that ribosomes of seedling roots of maize (Zea mays L.) contain the acidic phosphoproteins (P-proteins) known to form a flexible lateral stalk structure of the 60S subunit of eukaryotic ribosomes. The P-protein stalk, composed of P0, P1, and P2, interacts with elongation factors, mRNA, and tRNA during translation. Acidic proteins of 13 to 15.5 kD were released as a complex from ribosomes with 0.4 M NH4Cl/50% ethanol. Protein and cDNA sequence analysis confirmed that maize ribosomes contain one type of P1, two types of P2, and a fourth and novel P1/P2-type protein. This novel P-protein, designated P3, has the conserved C terminus of P1 and P2. P1, P2, and P3 are similar in deduced mass (11.4–12.2 kD) and isoelectric point (4.1–4.3). A 35.5- to 36-kD acidic protein was released at low levels from ribosomes with 1.0 M NH4Cl/50% ethanol and identified as P0. Labeling of roots with [32P]inorganic phosphate confirmed the in vivo phosphorylation of the P-proteins. Flooding caused dynamic changes in the P-protein complex, which affected the potential of ribosome-associated kinases and casein kinase II to phosphorylate the P-proteins. We discuss possible alerations of the ribosomal P-protein complex and consider that these changes may be involved in the selective translation of mRNA in flooded roots.
Sequence Analysis of the Cloned glossy8 Gene of Maize Suggests That It May Code for a β-Ketoacyl Reductase Required for the Biosynthesis of Cuticular Waxes
Authors: Xu X. , Dietrich C. R. , Delledonne M. , Xia Y. , Wen T. J. , Robertson D. S. , Nikolau B. J. , Schnable P. S.
Published: July 2002

The gl8 locus of maize (Zea mays L.) was previously defined by a mutation that reduces the amount and alters the composition of seedling cuticular waxes. Sixty independently derived gl8 mutant alleles were isolated from stocks that carried the Mutator transposon system. A DNA fragment that contains a Mu8 transposon and that co-segregates with one of these alleles, gl8-Mu3142, was identified and cloned. DNA flanking the Mu8 transposon was shown via allelic cross-referencing experiments to represent the gl8 locus. The gl8 probe revealed a 1.4-kb transcript present in wild-type seedling leaves and, in lesser amounts, in other organs and at other developmental stages. The amino acid sequence deduced from an apparently full-length gl8 cDNA exhibits highly significant sequence similarity to a group of enzymes from plants, eubacteria, and mammals that catalyzes the reduction of ketones. This finding suggests that the GL8 protein probably functions as a reductase during fatty acid elongation in the cuticular wax biosynthetic pathway.
Identification of Proliferation-Induced Genes in Arabidopsis thaliana (Characterization of a New Member of the Highly Evolutionarily Conserved Histone H2A.F/Z Variant Subfamily)
Authors: Callard D. , Mazzolini L.
Published: July 2002

The changes in gene expression associated with the reinitiation of cell division and subsequent progression through the cell cycle in Arabidopsis thaliana cell-suspension cultures were investigated. Partial synchronization of cells was achieved by a technique combining phosphate starvation and a transient treatment with the DNA replication inhibitor aphidicolin. Six cDNAs corresponding to genes highly induced in proliferating cells and showing cell-cycle-regulated expression were obtained by the mRNA differential display technique. Full-length cDNA clones (cH2BAt and cH2AvAt) corresponding to two of the display products were subsequently isolated. The cH2BAt clone codes for a novel histone H2B protein, whereas the cH2AvAt cDNA corresponds to a gene encoding a new member of the highly conserved histone H2A.F/Z subfamily of chromosomal proteins. Further studies indicated that H2AvAt mRNA expression is tightly correlated with cell proliferation in cell-suspension cultures, and that closely related analogs of the encoded protein exist in Arabidopsis. The implications of the conservation of histone H2A.F/Z variants in plants are discussed.
Characterization of a Gene for Spinach CAP160 and Expression of Two Spinach Cold-Acclimation Proteins in Tobacco1
Authors: Kaye Claudia , Neven Lisa , Hofig Andrea , Li Qin-Bao , Haskell Dale , Guy Charles
Published: July 2002

The cDNA sequence for CAP160, an acidic protein previously linked with cold acclimation in spinach (Spinacia oleracea L.), was characterized and found to encode a novel acidic protein of 780 amino acids having very limited homology to a pair of Arabidopsis thaliana stress-regulated proteins, rd29A and rd29B. The lack of similarity in the structural organization of the spinach and Arabidopsis genes highlights the absence of a high degree of conservation of this cold-stress gene across taxonomic boundaries. The protein has several unique motifs that may relate to its function during cold stress. Expression of the CAP160 mRNA was increased by low-temperature exposure and water stress in a manner consistent with a probable function during stresses that involve dehydration. The coding sequences for CAP160 and CAP85, another spinach cold-stress protein, were introduced into tobacco (Nicotiana tabacum) under the control of the 35S promoter using Agrobacterium tumefaciens-based transformation. Tobacco plants expressing the proteins individually or coexpressing both proteins were evaluated for relative freezing-stress tolerance. The killing temperature for 50% of the cells of the transgenic plants was not different from that of the wild-type plants. As determined by a more sensitive time/temperature kinetic study, plants expressing the spinach proteins had slightly lower levels of electrolyte leakage than wild-type plants, indicative of a small reduction of freezing-stress injury. Clearly, the heterologous expression of two cold-stress proteins had no profound influence on stress tolerance, a result that is consistent with the quantitative nature of cold-stress-tolerance traits.
Root Growth and Oxygen Relations at Low Water Potentials. Impact of Oxygen Availability in Polyethylene Glycol Solutions1
Authors: Verslues Paul E. , Ober Eric S. , Sharp Robert E.
Published: July 2002

Polyethylene glycol (PEG), which is often used to impose low water potentials (ψw) in solution culture, decreases O2 movement by increasing solution viscosity. We investigated whether this property causes O2 deficiency that affects the elongation or metabolism of maize (Zea mays L.) primary roots. Seedlings grown in vigorously aerated PEG solutions at ambient solution O2partial pressure (pO2) had decreased steady-state root elongation rates, increased root-tip alanine concentrations, and decreased root-tip proline concentrations relative to seedlings grown in PEG solutions of above-ambientpO2 (alanine and proline accumulation are responses to hypoxia and low ψw, respectively). Measurements of root pO2 were made using an O2 microsensor to ensure that increased solutionpO2 did not increase rootpO2 above physiological levels. In oxygenated PEG solutions that gave maximal root elongation rates, rootpO2 was similar to or less than (depending on depth in the tissue) pO2 of roots growing in vermiculite at the same ψw. Even without PEG, high solution pO2 was necessary to raise rootpO2 to the levels found in vermiculite-grown roots. Vermiculite was used for comparison because it has large air spaces that allow free movement of O2 to the root surface. The results show that supplemental oxygenation is required to avoid hypoxia in PEG solutions. Also, the data suggest that the O2 demand of the root elongation zone may be greater at low relative to high ψw, compounding the effect of PEG on O2 supply. Under O2-sufficient conditions root elongation was substantially less sensitive to the low ψwimposed by PEG than that imposed by dry vermiculite.
Adaptation of Active Proton Pumping and Plasmalemma ATPase Activity of Corn Roots to Low Root Medium pH1
Authors: Yan Feng , Feuerle Robert , Schäffer Stefanie , Fortmeier Helge , Schubert Sven
Published: July 2002

Corn (Zea mays L.) root adaptation to pH 3.5 in comparison with pH 6.0 (control) was investigated in long-term nutrient solution experiments. When pH was gradually reduced, comparable root growth was observed irrespective of whether the pH was 3.5 or 6.0. After low-pH adaptation, H+ release of corn roots in vivo at pH 5.6 was about 3 times higher than that of control. Plasmalemma of corn roots was isolated for investigation in vitro. At optimum assay pH, in comparison with control, the following increases of the various parameters were caused by low-pH treatment: (a) hydrolytic ATPase activity, (b) maximum initial velocity and Michaelis constant (c) activation energy of H+-ATPase, (d) H+-pumping activity, (e) H+ permeability of plasmalemma, and (f) pH gradient across the membranes of plasmalemma vesicles. In addition, vanadate sensitivity remained unchanged. It is concluded that plasmalemma H+-ATPase contributes significantly to the adaptation of corn roots to low pH. A restricted net H+release at low pH in vivo may be attributed to the steeper pH gradient and enhanced H+ permeability of plasmalemma but not to deactivation of H+-ATPase. Possible mechanisms responsible for adaptation of plasmalemma H+-ATPase to low solution pH during plant cultivation are discussed.
High-Temperature Perturbation of Starch Synthesis Is Attributable to Inhibition of ADP-Glucose Pyrophosphorylase by Decreased Levels of Glycerate-3-Phosphate in Growing Potato Tubers1
Authors: Geigenberger Peter , Geiger Michael , Stitt Mark
Published: July 2002

To investigate the short-term effect of elevated temperatures on carbon metabolism in growing potato (Solanum tuberosum L.) tubers, developing tubers were exposed to a range of temperatures between 19°C and 37°C. Incorporation of [14C]glucose (Glc) into starch showed a temperature optimum at 25°C. Increasing the temperature from 23°C or 25°C up to 37°C led to decreased labeling of starch, increased labeling of sucrose (Suc) and intermediates of the respiratory pathway, and increased respiration rates. At elevated temperatures, hexose-phosphate levels were increased, whereas the levels of glycerate-3-phosphate (3PGA) and phosphoenolpyruvate were decreased. There was an increase in pyruvate and malate, and a decrease in isocitrate. The amount of adenine diphosphoglucose (ADPGlc) decreased when tubers were exposed to elevated temperatures. There was a strong correlation between the in vivo levels of 3PGA and ADPGlc in tubers incubated at different temperatures, and the decrease in ADPGlc correlated very well with the decrease in the labeling of starch. In tubers incubated at temperatures above 30°C, the overall activities of Suc synthase and ADPGlc pyrophosphorylase declined slightly, whereas soluble starch synthase and pyruvate kinase remained unchanged. Elevated temperatures led to an activation of Suc phosphate synthase involving a change in its kinetic properties. There was a strong correlation between Suc phosphate synthase activation and the in vivo level of Glc-6-phosphate. It is proposed that elevated temperatures lead to increased rates of respiration, and the resulting decline of 3PGA then inhibits ADPGlc pyrophosphorylase and starch synthesis.
Visualization of Cavitated Vessels in Winter and Refilled Vessels in Spring in Diffuse-Porous Trees by Cryo-Scanning Electron Microscopy1
Authors: Utsumi Yasuhiro , Sano Yuzou , Fujikawa Seizo , Funada Ryo , Ohtani Jun
Published: July 2002

Xylem cavitation in winter and recovery from cavitation in the spring were visualized in two species of diffuse-porous trees, Betula platyphylla var.japonica Hara and Salix sachalinensis Fr. Schm., by cryo-scanning electron microscopy after freeze-fixation of living twigs. Water in the vessel lumina of the outer three annual rings of twigs of B. platyphylla var.japonica and of S. sachalinensisgradually disappeared during the period from January to March, an indication that cavitation occurs gradually in these species during the winter. In April, when no leaves had yet expanded, the lumina of most of the vessels of both species were filled with water. Many vessel lumina in twigs of both species were filled with water during the period from the subsequent growth season to the beginning of the next winter. These observations indicate that recovery in spring occurs before the onset of transpiration and that water transport through twigs occurs during the subsequent growing season. We found, moreover, that vessels repeat an annual cycle of winter cavitation and spring recovery from cavitation for several years until irreversible cavitation occurs.
Expression of Ornithine Decarboxylase Is Transiently Increased by Pollination, 2,4-Dichlorophenoxyacetic Acid, and Gibberellic Acid in Tomato Ovaries1
Authors: Alabadı́ David , Carbonell Juan
Published: July 2002

A cDNA encoding for a functional ornithine decarboxylase has been isolated from a cDNA library of carpels of tomato (Lycopersicon esculentum Mill.). Ornithine decarboxylase in tomato is represented by a single-copy gene that we show to be up-regulated during early fruit growth induced by 2,4-dichlorophenoxyacetic acid and gibberellic acid.
Evidence That Auxin-Induced Growth of Tobacco Leaf Tissues Does Not Involve Cell Wall Acidification
Authors: Keller Christopher P. , Van Volkenburgh Elizabeth
Published: July 2002

Interveinal strips (10 × 1.5 mm) excised from growing tobacco (Nicotiana tabacum L. cv Xanthi) leaves have an auxin-specific, epinastic growth response that is developmentally regulated and is not the result of ethylene induction (C.P. Keller, E. Van Volkenburgh [1997] Plant Physiol 113: 603–610). We report here that auxin (10 μm naphthalene acetic acid) treatment of strips does not result in plasma membrane hyperpolarization or detectable proton efflux. This result is in contrast to the expected responses elicited by 1 μm fusicoccin (FC) treatment, which in other systems mimics auxin growth promotion through stimulation of the plasma membrane H+-ATPase and resultant acid wall loosening; FC produced both hyperpolarization and proton efflux in leaf strips. FC-induced growth was much more inhibited by a strong neutral buffer than was auxin-induced growth. Measurements of the osmotic concentration of strips suggested that osmotic adjustment plays no role in the auxin-induced growth response. Although cell wall loosening of some form appears to be involved, taken together, our results suggest that auxin-induced growth stimulation of tobacco leaf strips results primarily from a mechanism not involving acid growth.
Expression of the Granule-Bound Starch Synthase I (Waxy) Gene from Snapdragon Is Developmentally and Circadian Clock Regulated1
Authors: Mérida Angel , Rodrı́guez-Galán José M. , Vincent Coral , Romero José M.
Published: July 2002

The granule-bound starch synthase I (GBSSI or waxy) enzyme catalyzes one of the enzymatic steps of starch synthesis. This enzyme is responsible for the synthesis of amylose and is also involved in building the final structure of amylopectin. Little is known about expression of GBSSI genes in tissues other than storage organs, such as seeds, endosperm, and tuber. We have isolated a gene encoding the GBSSI from snapdragon (Antirrhinum majus). This gene is present as a single copy in the snapdragon genome. There is a precise spatial and developmental regulation of its expression in flowers.GBSSI expression was observed in all floral whorls at early developmental stages, but it was restricted to carpel before anthesis. These results give new insights into the role of starch in later reproductive events such as seed filling. In leaves the mRNA level of GBSSI is regulated by an endogenous circadian clock, indicating that the transition from day to night may be accompanied by abolition of expression of starch synthesis genes. This mechanism does not operate in sink tissues such as roots when grown in the dark.
Characterization of P69E and P69F, Two Differentially Regulated Genes Encoding New Members of the Subtilisin-Like Proteinase Family from Tomato Plants
Authors: Jordá Lucia , Conejero Vicente , Vera Pablo
Published: July 2002

Subtilisin-like proteins represent an ancient family of serine proteases that are extremely widespread in living organisms. We report here the structure and genomic organization of two new transcriptionally active genes encoding proteins that belong to the P69 family of subtilisin-like proteases from tomato (Lycopersicon esculentum) plants. The two new members, P69E and P69F, are organized in a cluster and arranged in a tandem form. mRNA expression analysis and studies of transgenic Arabidopsis plants transformed with promoter-β-glucuronidase fusions for each of these two genes revealed that they are differentially regulated, with each showing a highly specific mRNA expression pattern.P69E mRNA is expressed only in roots, while P69F mRNA is expressed only in hydathodes. A comparison of all the P69 amino acid sequences, gene structure, expression profiles, and clustered organization suggests a working model for P69 gene family evolution.
Induction of an Extracellular Cyclic Nucleotide Phosphodiesterase as an Accessory Ribonucleolytic Activity during Phosphate Starvation of Cultured Tomato Cells
Authors: Abel Steffen , Nürnberger Thorsten , Ahnert Volker , Krauss Gerd-Joachim , Glund Konrad
Published: July 2002

During growth under conditions of phosphate limitation, suspension-cultured cells of tomato (Lycopersicon esculentum Mill.) secrete phosphodiesterase activity in a similar fashion to phosphate starvation-inducible ribonuclease (RNase LE), a cyclizing endoribonuclease that generates 2′:3′-cyclic nucleoside monophosphates (NMP) as its major monomeric products (T. Nürnberger, S. Abel, W. Jost, K. Glund [1990] Plant Physiol 92: 970–976). Tomato extracellular phosphodiesterase was purified to homogeneity from the spent culture medium of phosphate-starved cells and was characterized as a cyclic nucleotide phosphodiesterase. The purified enzyme has a molecular mass of 70 kD, a pH optimum of 6.2, and an isoelectric point of 8.1. The phosphodiesterase preparation is free of any detectable deoxyribonuclease, ribonuclease, and nucleotidase activity. Tomato extracellular phosphodiesterase is insensitive to EDTA and hydrolyzes with no apparent base specificity 2′:3′-cyclic NMP to 3′-NMP and the 3′:5′-cyclic isomers to a mixture of 3′-NMP and 5′-NMP. Specific activities of the enzyme are 2-fold higher for 2′:3′-cyclic NMP than for 3′:5′-cyclic isomers. Analysis of monomeric products of sequential RNA hydrolysis with purified RNase LE, purified extracellular phosphodiesterase, and cleared −Pi culture medium as a source of 3′-nucleotidase activity indicates that cyclic nucleotide phosphodiesterase functions as an accessory ribonucleolytic activity that effectively hydrolyzes primary products of RNase LE to substrates for phosphate-starvation-inducible phosphomonoesterases. Biosynthetical labeling of cyclic nucleotide phopshodiesterase upon phosphate starvation suggests de novo synthesis and secretion of a set of nucleolytic enzymes for scavenging phosphate from extracellular RNA substrates.
Differential Screening Indicates a Dramatic Change in mRNA Profiles during Grape Berry Ripening. Cloning and Characterization of cDNAs Encoding Putative Cell Wall and Stress Response Proteins
Authors: Davies Christopher , Robinson Simon P.
Published: July 2002

We used differential screening to isolate ripening-associated cDNAs from a Shiraz grape (Vitis vinifera L.) berry cDNA library. A rapid increase in the mRNA levels of a number of cDNAs not present in unripe fruit occurred in grape berries at the onset of ripening. The putative translation products of some of these clones had homologs in other species that are involved in cell wall structure. These included four proline-rich proteins, a small protein that is similar to the non-catalytic, N-terminal domain of some pectin methylesterases, and two other glutamate-rich proteins. The remainder of the clones encoded putative stress response proteins. These included two thaumatin-like proteins, a metallothionein, a transcription factor, a cytochrome P450 enzyme, and proteins induced by water, sugar, and/or cold stress in other species. Many of the homologs of the grape cDNAs thought to be involved in cell wall structure or stress-related responses also accumulate in a developmental manner in other plants. This may indicate that the grape mRNAs accumulate in response to stresses such as the storage of high concentrations of sugars and rapid cell expansion, or they may accumulate as part of the ripening developmental program.
Co-Association of CytochromefCatabolites and Plastid-Lipid-Associated Protein with Chloroplast Lipid Particles
Authors: Smith Matthew D. , Licatalosi Donny D. , Thompson John E.
Published: July 2002

Distinguishable populations of lipid particles isolated from chloroplasts of yellow wax bean (Phaseolus vulgaris L. cv Kinghorn Wax) leaves have been found to contain plastid-lipid-associated protein (J. Pozueta-Romero, F. Rafia, G. Houlné, C. Cheniclet, J.P. Carde, M.-L. Schantz, R. Schantz [1997] Plant Physiol 115: 1185–1194). One population is comprised of plastoglobuli obtained from sonicated chloroplasts by flotation centrifugation. Higher density lipid-protein particles isolated from chloroplast stroma by ultrafiltration constitute a second population. Inasmuch as the stromal lipid-protein particles contain plastid-lipid-associated protein, but are distinguishable from plastoglobuli in terms of their lipid and protein composition, they appear to be plastoglobuli-like particles. Of particular interest is the finding that plastoglobuli and the higher density lipid-protein particles both contain catabolites of the thylakoid protein, cytochromef. These observations support the view that there are distinguishable populations of plastoglobuli-like particles in chloroplasts. They further suggest that the formation of these particles may allow removal of protein catabolites from the thylakoid membrane that are destined for degradation as part of normal thylakoid turnover.
A Florigenic Effect of Sucrose inFuchsia hybridaIs Blocked by Gibberellin-Induced Assimilate Competition
Authors: King Rod W. , Ben-Tal Yossie
Published: July 2002

The use of gas chromatography-mass spectrometry-selected ion monitoring along with a 13C internal standard has allowed sensitive measurements of the sucrose (Suc) content of individual shoot apices of Fuchsia hybrida. With intact plants, as the photosynthetic irradiance increased, so did shoot apex Suc content, reaching saturation at about 500 μmol m−2s−1. These same plants flowered at the higher irradiances, remaining vegetative in 10-h short days at an irradiance of 230 μmol m−2 s−1. The strong correlation (r = 0.93) in these studies between flowering and shoot apex Suc content indicates a role for Suc as a stimulus to flowering in this species. However, Suc is not the long-day (LD) “florigen” of F. hybridabecause 2 to 4 LD given as a 14-h low-irradiance photoperiod extension (10–15 μmol m−2 s−1) induced flowering but without increase in shoot apex Suc content. Flowering induced by either pathway, the LD- or the Suc-mediated one, was inhibited by applying gibberellin (GA) to the shoot tip. Such inhibition of flowering by GA, at least for the LD pathway, was associated with a reduced apex Suc content, enhanced elongation of subapical stem tissue, and a reduced import into the shoot apex of leaf-sourced assimilate. Thus, our findings show how GA inhibits flowering of F. hybrida and confirm the importance of nutrient diversion in regulating flowering.
Cloning of an Arabidopsis Patatin-Like Gene, STURDY, by Activation T-DNA Tagging
Authors: Huang Shihshieh , Cerny R. Eric , Bhat Deepti S. , Brown Sherri M.
Published: July 2002

Activation T-DNA tagging can generate dominant gain-of-function mutants by overexpression of a particular endogenous gene. We identified an activation-tagged mutant, sturdy, exhibiting a stiff inflorescence stem, thicker leaves, shorter siliques, larger seeds, round-shaped flowers, and delayed growth. It is most important that unlike its wild-type counterpart, this mutant is less prone to lodging. Cloning of STURDY revealed that in sturdy, there is an open reading frame containing a single intron encoding a patatin-like homolog. The T-DNA is inserted into the 3′ region of the second exon. The mutant phenotype was shown to be the result of overexpression of STURDY by mRNA analysis and transgenic studies. Preliminary histological studies have revealed an increase in cell number in the inflorescence stem of mutant plants; however, additional studies are needed to better understand the overexpression phenotype.
Sucrose Metabolism in Plastids
Authors: Gerrits Nathalie , Turk Stefan C.H.J. , van Dun Kees P.M. , Hulleman Stephan H.D. , Visser Richard G.F. , Weisbeek Peter J. , Smeekens Sjef C.M.
Published: July 2002

The question whether sucrose (Suc) is present inside plastids has been long debated. Low Suc levels were reported to be present inside isolated chloroplasts, but these were argued to be artifacts of the isolation procedures used. We have introduced Suc-metabolizing enzymes in plastids and our experiments suggest substantial Suc entry into plastids. The enzyme levansucrase from Bacillus subtilisefficiently synthesizes fructan from Suc. Targeting of this enzyme to the plastids of tobacco (Nicotiana tabacum) and potato (Solanum tuberosum) plants leads to high-level fructan accumulation in chloroplasts and amyloplasts, respectively. Moreover, introduction of this enzyme in amyloplasts leads to an altered starch structure. Expression of the yeast invertase in potato tuber amyloplasts results in an 80% reduction of total Suc content, showing efficient hydrolysis of Suc by the plastidic invertase. These observations suggest that Suc can enter plastids efficiently and they raise questions as to its function and metabolism in this organelle.
A Pollen Coat Protein, SP11/SCR, Determines the PollenS-Specificity in the Self-Incompatibility ofBrassica Species
Authors: Shiba Hiroshi , Takayama Seiji , Iwano Megumi , Shimosato Hiroko , Funato Miyuki , Nakagawa Tomofumi , Che Fang-Sik , Suzuki Go , Watanabe Masao , Hinata Kokichi , Isogai Akira
Published: July 2002

Many flowering plants have evolved self-incompatibility (SI) systems to prevent inbreeding. In the Brassicaceae, SI is genetically controlled by a single polymorphic locus, termed theS-locus. Pollen rejection occurs when stigma and pollen share the same S-haplotype. Recognition ofS-haplotype specificity has recently been shown to involve at least two S-locus genes,S-receptor kinase (SRK) andS-locus protein 11 or S-locus Cys-rich (SP11/SCR). SRK encodes a polymorphic membrane-spanning protein kinase, which is the sole female determinant of the S-haplotype specificity. SP11/SCRencodes a highly polymorphic Cys-rich small basic protein specifically expressed in the anther tapetum and in pollen. In cauliflower (B. oleracea), the gain-of-function approach has demonstrated that an allele of SP11/SCRencodes the male determinant of S-specificity. Here we examined the function of two alleles of SP11/SCR ofB. rapa by the same approach and further established that SP11/SCR is the sole male determinant of SI in the genusBrassica sp. Our results also suggested that the 522-bp 5′-upstream region of theS  9  -SP11 gene used to drive the transgene contained all the regulatory elements required for the unique sporophytic/gametophytic expression observed for the nativeSP11 gene. Promoter deletion analyses suggested that the highly conserved 192-bp upstream region was sufficient for driving this unique expression. Furthermore, immunohistochemical analyses revealed that the protein product of the SP11 transgene was present in the tapetum and pollen, and that in pollen of late developmental stages, the SP11 protein was mainly localized in the pollen coat, a finding consistent with its expected biological role.
The Mitochondrial Isovaleryl-Coenzyme A Dehydrogenase of Arabidopsis Oxidizes Intermediates of Leucine and Valine Catabolism
Authors: Däschner Klaus , Couée Ivan , Binder Stefan
Published: July 2002

We recently identified a cDNA encoding a putative isovaleryl-coenzyme A (CoA) dehydrogenase in Arabidopsis (AtIVD). In animals, this homotetrameric enzyme is located in mitochondria and catalyzes the conversion of isovaleryl-CoA to 3-methylcrotonyl-CoA as an intermediate step in the leucine (Leu) catabolic pathway. Expression of AtIVD:smGFP4 fusion proteins in tobacco (Nicotiana tabacum) protoplasts and biochemical studies now demonstrate the in vivo import of the plant isovaleryl-CoA dehydrogenase (IVD) into mitochondria and the enzyme in the matrix of these organelles. Two-dimensional separation of mitochondrial proteins by blue native and SDS-PAGE and size determination of the native and overexpressed proteins suggest homodimers to be the dominant form of the plant IVD. Northern-blot hybridization and studies in transgenic Arabidopsis plants expressing Ativd promoter:gus constructs reveal strong expression of this gene in seedlings and young plants grown in the absence of sucrose, whereas promoter activity in almost all tissues is strongly inhibited by exogeneously added sucrose. Substrate specificity tests with AtIVD expressed in Escherichia coli indicate a strong preference toward isovaleryl-CoA but surprisingly also show considerable activity with isobutyryl-CoA. This strongly indicates a commitment of the enzyme in Leu catabolism, but the activity observed with isobutyryl-CoA also suggests a parallel involvement of the enzyme in the dehydrogenation of intermediates of the valine degradation pathway. Such a dual activity has not been observed with the animal IVD and may suggest a novel connection of the Leu and valine catabolism in plants.
Male Meiotic Spindle Lengths in Normal and Mutant Arabidopsis Cells
Authors: Yang Ming , Ma Hong
Published: July 2002

Spindle elongation is crucial to normal chromosome separation in eukaryotes; in particular, it is required for or associated with the extension of distance between spindle poles and the further moving apart of the already separated chromosomes. However, little is known about the relationship between spindle elongation and the status of chromosome separation, and it is unknown whether spindle elongation in different organisms shares any quantitative feature. The Arabidopsisask1-1 mutant might be a unique material for addressing these questions because it appears to have functional spindles, but a severe defect in homolog separation at male anaphase I (M. Yang, Y. Hu, M. Lodhi, W.R. McCombie, H Ma [1999] Proc Natl Acad Sci USA 96: 11416–11421). We have characterized male meiotic spindle lengths in wild-type and the ask1-1 mutant plants. We observed that during meiosis I some ask1-1 cells had spindles that were similar in length to fully elongated normal spindles, but the chromosomes in these cells did not show appreciable movement from the equator. Furthermore, greater movement of chromosomes from the equator was usually found in the ask1-1 cells that had longer than normal spindles. These results suggest that additional elongation of ask1-1 spindles occurred; one possible reason for the extra-long spindles may be that it is a consequence of chromosome non-separation. We also found that normal and ask1-1spindle lengths are clustered at discrete values, and their differences are of multiples of 0.7 μm. A search of the literature revealed that in each of several organisms, spindle lengths also differ by multiples of 0.7 μm. These findings strongly suggest that the spindle elongates in response to status of chromosome separation, and perhaps there are conserved mechanisms controlling the extent of spindle elongation.
Pollen Germinates Precociously in the Anthers of raring-to-go, an Arabidopsis Gametophytic Mutant
Authors: Johnson Sheila A. , McCormick Sheila
Published: July 2002

Pollen hydration is usually tightly regulated and occurs in vivo only when desiccated pollen grains acquire water from the female, thus enabling pollen tube growth. Pollen tubes are easily visualized by staining with decolorized aniline blue, a stain specific for callose. We identified a mutant, raring-to-go, in which pollen grains stained for callose before anther dehiscence. Whenraring-to-go plants are transferred to high humidity, pollen tubes dramatically elongate within the anther. As early as the bicellular stage, affected pollen grains in raring-to-goplants acquire or retain water within the anther, and precociously germinate. Thus, the requirement for contact with the female is circumvented. We used pollen tetrad analysis to show thatraring-to-go is a gametophytic mutation, to our knowledge the first gametophytic mutation in Arabidopsis that affects early events in the pollination pathway. To aid in identifyingraring-to-go alleles, we devised a new technique for screening pollen in bulk with decolorized aniline blue. We screened a new M1 mutagenized population and identified several additional mutants with a raring-to-go-like phenotype, demonstrating the usefulness of this technique. Further, we isolated other mutants (gift-wrapped pollen, polka dot pollen, and emotionally fragile pollen) with unexpected patterns of callose staining. We suggest thatraring-to-go and these other mutants may help dissect components of the pathway that regulates pollen hydration and pollen tube growth.
Expression and Chloroplast Targeting of Cholesterol Oxidase in Transgenic Tobacco Plants
Authors: Corbin David R. , Grebenok Robert J. , Ohnmeiss Thomas E. , Greenplate John T. , Purcell John P.
Published: July 2002

Cholesterol oxidase represents a novel type of insecticidal protein with potent activity against the cotton boll weevil (Anthonomus grandis grandis Boheman). We transformed tobacco (Nicotiana tabacum) plants with the cholesterol oxidasechoM gene and expressed cytosolic and chloroplast-targeted versions of the ChoM protein. Transgenic leaf tissues expressing cholesterol oxidase exerted insecticidal activity against boll weevil larvae. Our results indicate that cholesterol oxidase can metabolize phytosterols in vivo when produced cytosolically or when targeted to chloroplasts. The transgenic plants exhibiting cytosolic expression accumulated low levels of saturated sterols known as stanols, and displayed severe developmental aberrations. In contrast, the transgenic plants expressing chloroplast-targeted cholesterol oxidase maintained a greater accumulation of stanols, and appeared phenotypically and developmentally normal. These results are discussed within the context of plant sterol distribution and metabolism.
Synergistic, antagonistic and biocidal effects of amino (trimethylene phosphonic acid), polyacrylamide and Zn2+ on the inhibition of corrosion of mild steel in neutral aqueous environment
Authors: Rajendran S. , Apparao B.V. , Palaniswamy N.
Published: July 2002

The corrosion rates of mild steel in a neutral aqueous environment containing 60 ppm C1‐ in the absence and presence of the sodium salt of amino (trimethylene phosphonic acid) (ATMP), polyacrylamide (PAA) and Zn2+ have been evaluated by the classical weight‐loss method. The formulation consisting of 50 ppm PAA and 50 ppm Zn2+ and also the ATMP (300 ppm) ‐ZN2+ (50 ppm) system shows synergistic effect while the formulation consisting of 300 ppm ATMP and 50 ppm PAA shows antagonistic effect. The formulation consisting of 300 ppm ATMP, 50 ppm Zn2+ and 50 ppm PAA has 98 per cent corrosion inhibition efficiency and 99.9 per cent biocidal efficiency. The mechanistic aspects of corrosion inhibition are based, in a holistic way, on the results obtained from potentiostatic polarization study, X‐ray diffraction technique, UV‐visible, FTIR and luminescence spectra. Found that the protective film consists of FE2+‐ATMP complex, Fe2+‐PAA complex and Zn(OH)2.
Study of low cost eco‐friendly compounds as corrosion inhibitors for cooling systems
Authors: Farooqi I.H. , Hussain Aqbal , Saini P.A. , Quraishi M.A.
Published: July 2002

Attempts are made to utilize the aqueous extracts of natural compounds, namely cordia latifolia and curcumin, as corrosion inhibitors for mild steel in cooling systems, and their inhibition efficiencies are compared with that of Hydroxyethylidene 1‐1 diphosphonic acid (HEDP). HEDP is also blended with aqueous extracts of natural compounds so as to improve their inhibition efficiency. The blowdown of the cooling system is also analysed for environmental factors.
Dietary supplement use in later life
Authors: Johnson Angela E. , Donkin Angela J.M. , Morgan Kevin , Neale Roger J. , Lilley Jeanette M.
Published: July 2002

Describes self‐reported dietary supplement use among elderly people in the UK and explores the association between supplement use and socioeconomic, physical and dietary factors. A three‐phase survey incorporating face‐to‐face interviews, self‐completed four‐day dietary diaries with a food frequency questionnaire and follow‐up face‐to‐face interviews took place in urban Nottingham and rural Nottinghamshire, Lincolnshire and Leicestershire. A total of 957 elderly people (aged over 65) were randomly selected from general practitioner lists. A total of 36 per cent of the urban respondents and 41 per cent of rural respondents were taking at least one dietary supplement. Respondents who did not smoke were of a higher social class and had more qualifications were the most likely to take supplements. Fish oil was the most commonly taken supplement, followed by multivitamins, garlic tablets and vitamin C. The mean dietary intake of all respondents was above the reference nutrient intakes (RNIs) for nutrients studied. The diets of supplement users, excluding nutrients derived from supplementation, contained more iron, vitamin C, fibre, folate and oily fish than non‐users. Dietary supplement usage is widespread among the UK elderly, although supplement users within this sample do not appear to have diets which warrant supplementation to meet RNIs in the nutrients studied. Many advantages are, however, reported of consuming fish oils, garlic and higher intakes of anti‐oxidants.
Effects of repeat consumption on pleasantness, preference and intake
Authors: Hetherington Marion M. , Bell Ali , Rolls Barbara J.
Published: July 2002

The pleasantness of a food declines with consumption and this phenomenon has been demonstrated reliably in the short‐term. To investigate long‐term effects of repeat consumption on pleasantness, preference and intake, 21 volunteers consumed either a salty snack (french fries) or sweet snack (chocolate) every day for 15 days. Four dependent variables were measured: pleasantness ratings, ranked preference, frequency of consumption and ad libitum intake. Daily pleasantness of taste ratings decreased across the exposure period only for chocolate. Ranked preference for chocolate declined during the sweet snack condition and increased during the salty snack condition. Preference for french fries remained the same during the salty snack condition and increased during the sweet snack condition. Frequency of consuming chocolate outside the laboratory decreased during the sweet snack exposure. No such pattern was found for french fries in either condition. Ad libitum intake in the laboratory remained the same over time for both foods. Short‐term sensory‐specific satiety within the eating episode was consistent over time. Therefore, long‐term monotony effects were found only for pleasantness, preference and frequency of eating chocolate following repeated exposure, but these changes had no impact on ad libitum intake. Systematic, repeat exposure to a single food provides a useful paradigm for investigating the development of monotony.
Competence development as a key organisational strategy ‐ experiences of European companies
Authors: Nyhan Barry
Published: July 2002

Competence development is seen as one of the critical strategic factors ensuring companies’ competitiveness. This has given rise to much discussion on how to create organisational and learning environments, such as learning organisations, which foster employees’ skills and sense of initiative and responsibility. This paper examines the experiences of a number of European manufacturing and process companies, which on the surface appear to have similar innovative competence development strategies. However, when analysed more closely, it emerges that these firms have different perspectives on the position competence development holds in the hierarchy of company values and strategies. The kinds of competencies developed in these companies and the learning approaches used are also discussed.
Hydrodynamics of a slider cylinder on a parallel track: mobility method of solution
Authors: Mucino V.H. , Sun K. , Smith J.E.
Published: July 2002

The system studied here consists of a non‐rotating cylinder sliding inside a fully lubricated parallel track with a prescribed longitudinal velocity, carrying a transverse load (normal to the track). Reynolds equations are used for the particular case of a non‐rotating sliding cylinder in a fully lubricated track. Two short‐bearing mobility charts are developed for a normalized clearance track (equivalent to those developed by Booker for journal‐bearings). Pressure distributions around the cylinder and motion paths within the clearance track are produced for prescribed transverse loading and longitudinal speed requirements for hydrodynamic analysis purposes. Numerical application examples are presented for general and specific cases at the end.
Career strategies to strengthen graduate employees’ employment position in the Hong Kong labour market
Authors: Lau Agnes , Pang Mary
Published: July 2002

This study investigates the significance of developing career goals and adopting appropriate career strategies during the first two years of employment after graduation. Data were collected from a sample of 300 graduate employees in Hong Kong during a time when job competition has been increasingly tough. Results indicate that respondents tend to use strategies such as “enhancing promotability” (performing effectively, acquiring skills, building networks) and “improving image with superiors” (conforming to expectations, highlighting accomplishments) more frequently than “establishing external contacts” (joining professional bodies and trade associations) during early career. The relationships of career goals and strategies to satisfaction with salary and hierarchical progression are also examined. Factors such as “developing career goals and plans” and “improving image with superiors” are positively and significantly related to satisfaction with progression. Practical implications of the study findings on individuals and organizations are discussed.
Project management via earned value
Authors: Raby Michael
Published: July 2002

The concept of “earned value” can be very useful in controlling large, expensive projects. It offers a consistent view across time and across a number of projects. It can be complex to use, but it offers sophisticated progress monitoring. Outlines the basic concepts and shows how earned value is used to measure, monitor and control large and complex projects.
Exploring Lawler’s new pay theory through the case of Finbank’s reward strategy for managers
Authors: Lewis Philip
Published: July 2002

This article seeks to establish the extent to which a major bank’s (Finbank) reward strategy for managers demonstrates the plausibility of Lawler’s model of reward strategy. This model argues that business strategy implies individual and organisational behaviours which dictate the content of reward strategy. In addition, three critical elements of the reward system need to be aligned for the system to be effective: the organisation’s core values; the implementation process; and the structure. The data collected demonstrate that Lawler’s model presents three major complications. It over‐simplifies the process of strategy formulation and content; it gives equal importance to values, structure and process although the data showed that the last was of the greatest significance; and it is represented as unitarist and deterministic.
HRM – The Reinvention of Modern Management?
Authors: Clark Ian
Published: July 2002

Critical and prescriptive evaluation of human resource management (HRM)
tells us little about the direction in which its practice and rationale
purport to push management. Contends that the prevailing course of HRM
ventures to make management more entrepreneurial. Distinguishes between
the spirit and substance of HRM. The former propagates “empowering”
employees and line managers to square the circle of increased
competition, improved efficiency/productivity and financial stringency.
The substance of HRM involves a reconfiguration of existing management
structures in an effort to re‐create an entrepreneurial philosophy in
management practice. First distinguishes entrepreneurship from
traditionally defined management. Second, locates disparate HRM
initiatives as entrepreneurial. Finally examines tensions between the
two forms of management by reference to contemporary sources. In
conclusion seeks to demonstrate that substance makes spirit a utopian
vision, at least in the UK context.
Situational leadership theory in Taiwan: a different culture perspective
Authors: Silverthorne Colin
Published: July 2002

Reports a study to investigate the applicability of situational leadership theory within the Republic of China (Taiwan). The study was conducted in a large construction company with a broad diversity of managerial responsibilities. The LEAD‐Self instrument was given to a large sample of managers, to determine their perception of their own leadership style. Employees completed the LEAD‐Other questionnaire, to give their perceptions of their manager. Productivity scores were also established for each manager using measures of absenteeism, turnover, overall profitability and quality of work. The results indicated that the situational leadership theory does have applicability in Taiwan; there was a good match between the self‐perception of leaders and perceptions by peers, superiors and subordinates and between the LEAD‐Self score and LEAD‐Other; also that leadership adaptability was directly related to productivity as measured by absenteeism, turnover rates, profitability and, to a lesser extent, quality.