bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Glycosylphosphatidylinositol-Anchored Phosphatase fromSpirodela oligorrhiza Is a Purple Acid Phosphatase
Authors: Nakazato Hiroshi , Okamoto Takashi , Nishikoori Miwa , Washio Kenji , Morita Naoki , Haraguchi Kensaku , Thompson Guy A. , Okuyama Hidetoshi 
Published: July 2002

Abstract
We recently presented clear evidence that the major low-phosphate-inducible phosphatase of the duckweedSpirodela oligorrhiza is a glycosylphosphatidylinositol (GPI)-anchored protein, and, to our knowledge, is the first described from higher plants (N. Morita, H. Nakazato, H. Okuyama, Y. Kim, G.A. Thompson, Jr. [1996] Biochim Biophys Acta 1290: 53–62). In this report the purified 57-kD phosphatase is shown to be a purple metalloenzyme containing Fe and Mn atoms and having an absorption maximum at 556 nm. The phosphatase activity was only slightly inhibited by tartrate, as expected for a purple acid phosphatase (PAP). Furthermore, the protein cross-reacted with an anti-Arabidopsis PAP antibody on immunoblots. The N-terminal amino acid sequence of the phosphatase was very similar to those of Arabidopsis, red kidney bean (Phaseolus vulgaris), and soybean (Glycine max) PAP. Extracts of S. oligorrhiza plants incubated with the GPI-specific precursor [3H]ethanolamine were treated with antibodies raised against the purified S. oligorrhizaphosphatase. Radioactivity from the resulting immunoprecipitates was specifically associated with a 57-kD band on sodium dodecyl sulfate-polyacrylamide gels. These results, together with previous findings, strongly indicate that the GPI-anchored phosphatase ofS. oligorrhiza is a PAP.
Export of Carbon from Chloroplasts at Night
Authors: Schleucher Jürgen , Vanderveer Peter J. , Sharkey Thomas D. 
Published: July 2002

AbstractHexose export from chloroplasts at night has been inferred in previous studies of mutant and transgenic plants. We have tested whether hexose export is the normal route of carbon export from chloroplasts at night. We used nuclear magnetic resonance to distinguish glucose (Glc) made from hexose export and Glc made from triose export. Glc synthesized in vitro from fructose-6-phosphate in the presence of deuterium-labeled water had deuterium incorporated at C-2, whereas synthesis from triose phosphates caused C-2 through C-5 to become deuterated. In both tomato (Lycopersicon esculentum L.) and bean (Phaseolus vulgaris L.), Glc from sucrose made at night in the presence of deuterium-enriched water was deuterated only in the C-2 position, indicating that &gt;75% of carbon is exported as hexoses at night. In darkness the phosphate in the cytosol was 28 mm, whereas that in the chloroplasts was 5 mm, but hexose phosphates were 10-fold higher in the cytosol than in the chloroplasts. Therefore, hexose phosphates would not move out of chloroplasts without the input of energy. We conclude that most carbon leaves chloroplasts at night as Glc, maltose, or higher maltodextrins under normal conditions.
The Wheat Peptidyl Prolylcis-trans-Isomerase FKBP77 Is Heat Induced and Developmentally Regulated1
Authors: Kurek Isaac , Aviezer Keren , Erel Noa , Herman Eliot , Breiman Adina 
Published: July 2002

AbstractWe isolated a cDNA encoding a 568-amino acid, heat-stress-induced peptidyl prolyl isomerase belonging to the FK506-binding-protein (FKBP) family. The open reading frame encodes for a peptidyl prolyl isomerase that possesses three FKBP-12-like domains, a putative tetratricopeptide motif, and a calmodulin-binding domain. Specific antibodies showed that the open reading frame encodes a heat-induced 77-kD protein, the wheat FKBP77 (wFKBP77), which exhibits 84% identity with the wFKBP73 and 42% identity with the human FKBP59. Because of the high similarity in sequence to wFKBP73, wFKBP77 was designated as the heat-induced isoform. The wFKBP77 mRNA steady-state level was 14-fold higher at 37°C than at 25°C. The wFKBP77 transcript abundance was the highest in mature embryos that had imbibed and 2-d-old green shoots exposed to 37°C, and decreased to 6% in 6-d-old green shoots. The transcript level returned to the level detected at 25°C after recovery of the embryos for 90 min at 25°C. We compared wFKBP73 and wFKBP77 with the heat-shock proteins having cognate and heat-stress-induced counterparts.
Antisense Expression of the CK2 α-Subunit Gene in Arabidopsis. Effects on Light-Regulated Gene Expression and Plant Growth1
Authors: Lee Yew , Lloyd Alan M. , Roux Stanley J. 
Published: July 2002

Abstract
The protein kinase CK2 (formerlycasein kinase II) is thought to be involved in light-regulated gene expression in plants because of its ability to phosphorylate transcription factors that bind to the promoter regions of light-regulated genes in vitro. To address this possibility in vivo and to learn more about the potential physiological roles of CK2 in plants, we transformed Arabidopsis with an antisense construct of the CK2 α-subunit gene and investigated both morphological and molecular phenotypes. Antisense transformants had a smaller adult leaf size and showed increased expression ofchs in darkness and of cab andrbcS after red-light treatment. The latter molecular phenotype implied that CK2 might serve as one of several negative and quantitative effectors in light-regulated gene expression. The possible mechanism of CK2 action and its involvement in the phytochrome signal transduction pathway are discussed.
Characterization ofMdMADS2, a Member of theSQUAMOSASubfamily of Genes, in Apple1
Authors: Sung Soon-Kee , Yu Gyung-Hee , An Gynheung 
Published: July 2002

AbstractA MADS-box gene,MdMADS2, was isolated from the apple (Malus × domestica Borkh.) var Fuji and its developmental expression pattern was studied during flower development. MdMADS2 shares a high degree of amino acid sequence identity with the SQUAMOSA subfamily of genes. RNA blot analysis showed that MdMADS2 is transcribed through all stages of flower development, and its transcription was seen in the four floral organs. RNA in situ hybridization revealed that the MdMADS2 mRNA is expressed both in the inflorescence meristem and in the floral meristem. The MdMADS2transcript was detected at all stages of flower development. Protein localization analysis showed that MdMADS2 protein was excluded from the stamen and carpel primordia, in which a considerableMdMADS2 mRNA signal was detected. This indicates that posttanscriptional regulation may be involved in theMdMADS2-mediated control of flower development. Transgenic tobacco expressing the MdMADS2 gene from the cauliflower mosaic virus 35S promoter showed early flowering and shorter bolts, but did not show any homeotic changes in the floral organs. These results suggest that MdMADS2 plays an important role during early stages of flower development.
Oligogalacturonic Acid and Chitosan Reduce Stomatal Aperture by Inducing the Evolution of Reactive Oxygen Species from Guard Cells of Tomato and Commelina communis
Authors: Lee Sumin , Choi Hyunjung , Suh SuJeoung , Doo In-Suk , Oh Ki-Young , Jeong Choi Eun , Schroeder Taylor Ann T. , Low Philip S. , Lee Youngsook 
Published: July 2002

Abstract
Stomatal opening provides access to inner leaf tissues for many plant pathogens, so narrowing stomatal apertures may be advantageous for plant defense. We investigated how guard cells respond to elicitors that can be generated from cell walls of plants or pathogens during pathogen infection. The effect of oligogalacturonic acid (OGA), a degradation product of the plant cell wall, and chitosan (β-1,4-linked glucosamine), a component of the fungal cell wall, on stomatal movements were examined in leaf epidermis of tomato (Lycopersicon esculentum L.) andCommelina communis L. These elicitors reduced the size of the stomatal aperture. OGA not only inhibited light-induced stomatal opening, but also accelerated stomatal closing in both species; chitosan inhibited light-induced stomatal opening in tomato epidermis. The effects of OGA and chitosan were suppressed when EGTA, catalase, or ascorbic acid was present in the medium, suggesting that Ca2+ and H2O2 mediate the elicitor-induced decrease of stomatal apertures. We show that the H2O2 that is involved in this process is produced by guard cells in response to elicitors. Our results suggest that guard cells infected by pathogens may close their stomata via a pathway involving H2O2 production, thus interfering with the continuous invasion of pathogens through the stomatal pores.
The Enzymatic Activity of Fungal Xylanase Is Not Necessary for Its Elicitor Activity
Authors: Enkerli Jürg , Felix Georg , Boller Thomas 
Published: July 2002

AbstractFungal xylanases fromTrichoderma spp. are potent elicitors of defense responses in various plants. To determine whether enzymatic activity is necessary for elicitor activity, we used site-directed mutagenesis to reduce the catalytic activity of xylanase II from Trichoderma reesei. For this, the glutamic acid residue at position 210, which is part of the active center in this family of enzymes, was changed to either aspartic acid (E210D) or serine (E210S). Wild-type and mutated forms of xylanase II were expressed in yeast cells and purified to homogeneity. Compared with the wild-type form of xylanase II, E210D had &gt;100-fold and E210S 1,000-fold lower enzymatic activity. In contrast, these mutated forms showed no comparable drop in elicitor activity. They fully stimulated medium alkalinization and ethylene biosynthesis in suspension-cultured tomato (Lycopersicon esculentum) cells, as well as hypersensitive necrosis in leaves of tomato and tobacco (Nicotiana tabacum) plants. These results provide direct evidence that enzyme activity is not necessary for elicitor activity of fungal xylanase.
A Transglutaminase Immunologically Related to Tissue Transglutaminase Catalyzes Cross-Linking of Cell Wall Proteins inChlamydomonas reinhardtii
Authors: Waffenschmidt Sabine , Kusch Thomas , Woessner Jeffrey Paul 
Published: July 2002

Abstract
The addition of primary amines to the growth medium of the unicellular green alga Chlamydomonas reinhardtii disrupts cell wall assembly in both vegetative and zygotic cells. Primary amines are competitive inhibitors of the protein-cross-linking activity of transglutaminases. Two independent assays for transglutaminase confirmed a burst of extracellular activity during the early stages of cell wall formation in both vegetative cells and zygotes. When non-inhibiting levels of a radioactive primary amine (14C-putrescine) were added to the growth medium, both cell types were labeled in a reaction catalyzed by extracellular transglutaminase. The radioactive label was found specifically in the cell wall proteins of both cell types, and acid hydrolysis of the labeled material released unmodified 14C-putrescine. Western blots of the proteins secreted at the times of maximal transglutaminase activity in both cell types revealed a single highly cross-reactive 72-kD band when screened with antibodies to guinea pig tissue transglutaminase. Furthermore, the proteins immunoprecipitated by this antiserum in vivo exhibited transglutaminase activity. We propose that this transglutaminase is responsible for an early cell wall protein cross-linking event that temporally precedes the oxidative cross-linking mediated by extracellular peroxidases.
Testing Models of Fatty Acid Transfer and Lipid Synthesis in Spinach Leaf Using in Vivo Oxygen-18 Labeling
Authors: Pollard Mike , Ohlrogge John 
Published: July 2002

Abstract
Oxygen-18 labeling has been applied to the study of plant lipid biosynthesis for the first time. [13C2 18O2]Acetate was incubated with spinach (Spinacia oleracea) leaves and the 18O content in fatty acid methyl esters isolated from different lipid classes measured by gas chromatography-mass spectometry. Fatty acids isolated from lipids synthesized within the plastid, such as monogalactosyldiacylglycerol, show an 18O content consistent with the exogenous acetate undergoing a single activation step and with the direct utilization of acyl-acyl carrier protein by the acyl transferases of the chloroplast. In contrast, fatty acids isolated from lipids assembled in the cytosol, such as phosphatidylcholine, show a 50% reduction in the 18O content. This is indicative of export of the fatty acyl groups from the plastid via a free carboxylate anion, and is consistent with the acyl-acyl carrier protein thioesterase:acyl-coenzyme A (CoA) synthetase mediated export mechanism. If this were not the case and the acyl group was transferred directly from acyl-acyl carrier protein to an acyl acceptor on the cytosolic side, there would be either complete retention of 18O or, less likely, complete loss of18O, but not a 50% loss of 18O. Thus, existing models for fatty acid transfer from the plastid and for spatially separate synthesis of “prokaryotic” and “eukaryotic” lipids have both been confirmed.
Soil Compaction. A Role for Ethylene in Regulating Leaf Expansion and Shoot Growth in Tomato?
Authors: Hussain Ahmed , Black Colin Ramsay , Taylor Ian Blackwood , Roberts Jeremy Alan 
Published: July 2002

Abstract
The role of ethylene in regulating growth in tomato (Lycopersicon esculentum Mill.) during compaction stress was examined using wild-type (cv Ailsa Craig) and transgenic (ACO1AS) genotypes; the latter has a reduced capacity to produce ethylene. Ethephon or silver ions were applied to increase ethylene production or block its action. Shoot growth in both genotypes was comparable in uncompacted (1.1 g cm−3) and uniformly compacted soil (1.5 g cm−3). However, a 1.1/1.5-g cm−3 split-pot treatment invoked marked genotypic differences: growth was reduced in cv Ailsa Craig but was comparable to uncompacted control plants in ACO1AS. As xylem sap abscisic acid levels were similar, abscisic acid was not responsible for inhibiting growth in cv Ailsa Craig. These genotypic differences in growth were accompanied by increased ethylene evolution in cv Ailsa Craig, suggesting that the ability of ACO1AS to maintain growth in the split-pot treatment reflected its lower ethylene levels, a view supported by the observation that excising the roots in the compacted compartment reduced ethylene evolution and restored shoot growth in cv Ailsa Craig. Treatment with silver restored shoot growth in cv Ailsa Craig, whereas treatment with ethephon reduced growth in ACO1AS. Thus, ethylene apparently has a key role in determining growth when tomato plants encounter differential soil compaction.
Wound-Induced Expression of the FAD7Gene Is Mediated by Different Regulatory Domains of Its Promoter in Leaves/Stems and Roots
Authors: Nishiuchi Takumi , Kodama Hiroaki , Yanagisawa Shuichi , Iba Koh 
Published: July 2002

Abstract
TheFAD7 gene is expressed preferentially in the chlorophyllous tissues of unwounded plants. Wounding activates the expression of the FAD7 gene not only in chlorophyllous tissues, but also in nonchlorophyllous tissues of stems and roots. Our previous study suggested that wound-responsive transcriptional activation by the FAD7 promoter in leaves/stems and roots is brought about by a jasmonic acid (JA)-independent and JA-dependent signaling pathway, respectively. In this paper, we show that a specific region (from −259 to −198) in the FAD7promoter is required for wound-activated expression of this gene in leaves and stems, while another region (from −521 to −363) is necessary not only for wound-activated but also for JA-responsive expression of this gene in roots. Thus, different regulatory regions of the FAD7 promoter mediate distinct wound-induced expression of this gene in leaves/stems and roots. Gel mobility shift assays revealed the wound-inducible DNA-binding activity to the −242/−223 region in both stem and leaf nuclear extracts. In fact, deletion of this region abolished wound response of theFAD7 promoter, suggesting the in vivo role of this site. Furthermore, we detected root nuclear factors interacting with the region from −433 to −363 of this promoter. Wounding and methyl jasmonate treatments induced differently these DNA-binding activities. These results suggest that different regulatory mechanisms mediate the wound-induced expression of the FAD7 gene in aerial and subterranean organs.
Amino Acid Transporters Are Localized to Transfer Cells of Developing Pea Seeds
Authors: Tegeder Mechthild , Offler Christina E. , Frommer Wolf B. , Patrick John W. 
Published: July 2002

AbstractTo determine the nature and cellular localization of amino acid transport in pea seeds, two cDNA clones belonging to the AAP family of H+/amino acid co-transporters (PsAAP1 and PsAAP2) were isolated from a cotyledon cDNA library of pea (Pisum sativum L.). Functional expression in the yeast amino acid uptake mutants 22Δ6AAL and 22Δ8AA showed that PsAAP1 mediates transport of neutral, acidic, and basic amino acids. RNA-blot analyses showed that PsAAP1 is expressed in seeds and vegetative organs, including amino acid sinks and sources, whereasPsAAP2 could not be detected. For developing seeds, transcripts of PsAAP1 were detected in coats and cotyledons, with seed coats giving a weak signal. In cotyledons, expression was highest in epidermal-transfer-cell-enriched tissue. RNA in situ hybridization analysis showed that PsAAP1 was predominantly present in epidermal transfer cells forming the outer surface of cotyledons, which abuts the seed coats. Overall, our observations suggest that this transporter, which is localized in transfer cells of cotyledons, might play a role in the uptake of the full spectrum of amino acids released from seed coats.
Post-Transcriptional Regulation Prevents Accumulation of Glutathione Reductase Protein and Activity in the Bundle Sheath Cells of Maize
Authors: Pastori Gabriela M. , Mullineaux Philip M. , Foyer Christine H. 
Published: July 2002

Abstract
Glutathione reductase (GR; EC1.6.4.2) activity was assayed in bundle sheath and mesophyll cells of maize (Zea mays L. var H99) from plants grown at 20°C, 18°C, and 15°C. The purity of each fraction was determined by measuring the associated activity of the compartment-specific marker enzymes, Rubisco and phosphoenolpyruvate carboxylase, respectively. GR activity and the abundance of GR protein and mRNA increased in plants grown at 15°C and 18°C compared with those grown at 20°C. In all cases GR activity was found only in mesophyll fractions of the leaves, with no GR activity being detectable in bundle sheath extracts. Immunogold labeling with GR-specific antibodies showed that the GR protein was exclusively localized in the mesophyll cells of leaves at all growth temperatures, whereas GR transcripts (as determined by in situ hybridization techniques) were observed in both cell types. These results indicate that post-transcriptional regulation prevents GR accumulation in the bundle sheath cells of maize leaves. The resulting limitation on the capacity for regeneration of reduced glutathione in this compartment may contribute to the extreme chilling sensitivity of maize leaves.
Thermal Effect of CO2 on Apoplastic Ice in Rye and Oat during Freezing
Authors: Livingston David P. , Olien C. Robert , Premakumar Ramaswamy 
Published: July 2002

Abstract
Meristematic tissues from rye (Secale cereale) and oat (Avena sativa) were studied in an isothermal calorimeter at −3°C. When the frozen tissue was placed in the calorimeter, the pressure increased within 4 d to 25 and 9 kPa above ambient pressure in the sample vessels containing crowns of rye and oat, respectively. Concurrently, the thermal output went down to −194 μW in rye over the 4-d period; this negative thermal activity could be accounted for by ice melting in the plants. When the pressure was released, the output from the calorimeter went from −194 to 229 μW within 1 h, suggesting that water had frozen in the plants. We propose that CO2 from respiration had dissolved in the water in the plants and caused melting of ice (heat absorption) due to the colligative properties of solutions. When the pressure was released, the CO2 came out of solution and the water froze (heat evolution). These thermal observations were duplicated in a simplified, non-biological system using a glycol/water mixture that was partially frozen at −3°C.
Disaccharide-Mediated Regulation of Sucrose:Fructan-6-Fructosyltransferase, a Key Enzyme of Fructan Synthesis in Barley Leaves
Authors: Müller Joachim , Aeschbacher Roger A. , Sprenger Norbert , Boller Thomas , Wiemken Andres 
Published: July 2002

Abstract
Previous work has indicated that sugar sensing may be important in the regulation of fructan biosynthesis in grasses. We used primary leaves of barley (Hordeum vulgare cv Baraka) to study the mechanisms involved. Excised leaf blades were supplied in the dark with various carbohydrates. Fructan pool sizes and two key enzymes of fructan biosynthesis, sucrose (Suc):Suc-1-fructosyltransferase (1-SST; EC 2.4.1.99) and Suc:fructan-6-fructosyltransferase (6-SFT; EC2.4.1.10) were analyzed. Upon supply of Suc, fructan pool sizes increased markedly. Within 24 h, 1-SST activity was stimulated by a factor of three and 6-SFT-activity by a factor of more than 20, compared with control leaves supplemented with mannitol (Mit). At the same time, the level of mRNA encoding 6-SFT increased conspicuously. These effects were increased in the presence of the invertase inhibitor 2,5-dideoxy-2,5-imino-d-mannitol. Compared with equimolar solutions of Suc, glucose (Glu) and fructose stimulated 6-SFT activity to a lesser extent. Remarkably, trehalose (Tre; Glc-α-1 and 1-α-Glc) had stimulatory effects on 6-SFT activity and, to a somewhat lesser extent, on 6-SFT mRNA, even in the presence of validoxylamine A, a potent trehalase inhibitor. Tre by itself, however, in the presence or absence of validoxylamine A, did not stimulate fructan accumulation. Monosaccharides phosphorylated by hexokinase but not or weakly metabolized, such as mannose (Man) or 2-deoxy-Glc, had no stimulatory effects on fructan synthesis. When fructose or Man were supplied together with Tre, fructan and starch biosynthesis were strongly stimulated. Concomitantly, phospho-Man isomerase (EC 5.3.1.8) activity was detected. These results indicate that the regulation of fructan synthesis in barley leaves occurs independently of hexokinase and is probably based on the sensing of Suc, and also that the structurally related disaccharide Tre can replace Suc as a regulatory compound.
A Dual Function α-Dioxygenase-Peroxidase and NAD+Oxidoreductase Active Enzyme from Germinating Pea Rationalizing α-Oxidation of Fatty Acids in Plants,
Authors: Saffert Alexander , Hartmann-Schreier Jenny , Schön Astrid , Schreier Peter 
Published: July 2002

Abstract
An enzyme with fatty acid α-oxidation activity (49 nkat mg−1; substrate: lauric acid) was purified from germinating pea (Pisum sativum) by a five-step procedure to apparent homogeneity. The purified protein was found to be a 230-kD oligomer with two dominant subunits, i.e. a 50-kD subunit with NAD+ oxidoreductase activity and a 70-kD subunit, homolog to a pathogen-induced oxygenase, which in turn shows significant homology to animal cyclooxygenase. On-line liquid chromatography-electrospray ionization-tandem mass spectrometry revealed rapid α-oxidation of palmitic acid incubated at 0°C with the purified α-oxidation enzyme, leading to (R)-2-hydroperoxypalmitic acid as the major product together with (R)-2-hydroxypalmitic acid, 1-pentadecanal, and pentadecanoic acid. Inherent peroxidase activity of the 70-kD fraction decreased the amount of the (R)-2-hydroperoxy product rapidly and increased the level of (R)-2-hydroxypalmitic acid. Incubations at room temperature accelerated the decline toward the chain-shortened aldehyde. With the identification of the dual functionα-dioxygenase-peroxidase (70-kD unit) and the related NAD+ oxidoreductase (50-kD unit) we provided novel data to rationalize all steps of the classical scheme ofα-oxidation in plants.