bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrophobic Protein Synthesized in the Pod Endocarp Adheres to the Seed Surface1
Authors: Gijzen Mark , Miller S. Shea , Kuflu Kuflom , Buzzell Richard I. , Miki Brian L.A. 
Published: July 2002

Abstract
Soybean (Glycine max[L.] Merr.) hydrophobic protein (HPS) is an abundant seed constituent and a potentially hazardous allergen that causes asthma in persons allergic to soybean dust. By analyzing surface extracts of soybean seeds with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and amino-terminal microsequencing, we determined that large amounts of HPS are deposited on the seed surface. The quantity of HPS present varies among soybean cultivars and is more prevalent on dull-seeded phenotypes. We have also isolated cDNA clones encoding HPS and determined that the preprotein is translated with a membrane-spanning signal sequence and a short hydrophilic domain. Southern analysis indicated that multiple copies of the HPS gene are present in the soybean genome, and that the HPS gene structure is polymorphic among cultivars that differ in seed coat luster. The pattern of HPS gene expression, determined by in situ hybridization and RNA analysis, shows that HPS is synthesized in the endocarp of the inner ovary wall and is deposited on the seed surface during development. This study demonstrates that a seed dust allergen is associated with the seed luster phenotype in soybean and that compositional properties of the seed surface may be altered by manipulating gene expression in the ovary wall.
The mur4 Mutant of Arabidopsis Is Partially Defective in the de Novo Synthesis of Uridine Diphosphol-Arabinose
Authors: Burget Emilie G. , Reiter Wolf-Dieter 
Published: July 2002

Abstract
To obtain information on the synthesis and function of arabinosylated glycans, themur4 mutant of Arabidopsis was characterized. This mutation leads to a 50% reduction in the monosaccharidel-arabinose in most organs and affects arabinose-containing pectic cell wall polysaccharides and arabinogalactan proteins. Feedingl-arabinose to mur4 plants restores the cell wall composition to wild-type levels, suggesting a partial defect in the de novo synthesis of UDP-l-arabinose, the activated sugar used by arabinosyltransferases. The defect was traced to the conversion of UDP-d-xylose to UDP-l-arabinose in the microsome fraction of leaf material, indicating thatmur4 plants are defective in a membrane-bound UDP-d-xylose 4-epimerase.
Rapid Repression of Maize Invertases by Low Oxygen. Invertase/Sucrose Synthase Balance, Sugar Signaling Potential, and Seedling Survival
Authors: Zeng Ying , Wu Yong , Avigne Wayne T. , Koch Karen E. 
Published: July 2002

Abstract
We show here that invertase gene expression and the invertase-sucrose (Suc) synthase ratio decrease abruptly in response to low oxygen in maize root tips. In addition to aiding in the conservation of carbon and possibly ATP, this response has the potential to directly affect sugar signaling relative to carbon flux. Experiments were motivated by the potential for a reduced invertase/Suc synthase balance to alter the impact of respiratory and/or membrane carbon flux on sugar signaling. Maize (Zea mays L.) seedlings with 5-cm primary roots were exposed to anoxic (0% [v/v] O2), hypoxic (3% [v/v] O2), and aerobic conditions. Rapid repression of theIvr1 and Ivr2 maize invertases by low oxygen was evident in root tips within 3 h at both the transcript and activity levels. The speed and extent of this response increased with the degree of oxygen deprivation and differed with genotypes. This decrease in expression also contrasted markedly to that of other genes for respiratory Suc metabolism, such as Suc synthases, which typically increased or remained constant. Although previous work showed that the contrasting effects of sugars on Suc synthase genes were reflected in their regulation by hypoxia and anoxia, the same was not observed for the differentially sugar-responsive invertases. Theoretically advantageous reductions in the invertase/Suc synthase balance thus resulted. However, where this response was extreme (an Oh43 inbred), total sucrolytic capacity dropped below an apparent minimum and root tip viability was reduced. Paradoxically, only Oh43 seedlings showed survival levels &gt;80% (versus &lt;50%) after extreme, long-term stress, suggesting a possible advantage for multiple means of reducing sink activity. Overall, our results demonstrate a rapid change in the regulation and balance of invertases and Suc synthases that could have an immediate impact on limiting the extent of Suc cleavage and reducing the extent of concomitant, hexose-based sugar signaling under low oxygen.
A Re-Evaluation of the Relative Roles of Two Invertases, INCW2 and IVR1, in Developing Maize Kernels and Other Tissues
Authors: Carlson Susan J. , Chourey Prem S. 
Published: July 2002

Abstract
We have examined the relative abundance and distribution of the transcripts and protein products of a cell wall gene (Incw2) and a soluble invertase gene (Ivr1) to better understand their relative roles during maize (Zea mays L.) kernel development. In developing kernels the steady-state levels of Incw2 transcript increased dramatically from 0 to 12 d after pollination, whileIvr1 transcript, in contrast to a previous report, was undetectable. Consistent with the RNA expression data, the IVR1 protein could not be detected in kernel extracts using antisera raised to a synthetic peptide. Fractionation of the soluble form of invertase from developing kernels by isoelectric focusing and protein blots suggested that the enzyme activity was due to contamination of the cell wall invertase protein. A similar observation was made in a maize cell suspension culture in which Ivr1 RNA, but not IVR1 protein, was significantly modulated by sugars in the medium. Protein-blot analyses of the soluble enzyme activity suggested that changes in the enzyme activity are attributable to a cell wall invertase protein in the soluble fraction. Based on the collective evidence, we propose that the cell wall, but not the soluble invertase, is critical to heterotrophic sinks such as cell suspension cultures and developing kernels.
The Redox State Regulates RNA Degradation in the Chloroplast ofChlamydomonas reinhardtii
Authors: Salvador Maria L. , Klein Uwe 
Published: July 2002

Abstract
A Chlamydomonas reinhardtii chloroplast transformant, designated MU7, carrying a chimeric (rbcL promoter: β-glucuronidase [GUS]:psaB 3′ end) gene whose transcripts have been found previously to be unstable in light (half-life of 20 min in light as opposed to a half-life of 5 h in the dark), was used to study the role of electron transport and of the redox state in the degradation of chloroplast transcripts in the light. Blocking photosynthetic electron transport with 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) prevented the light-dependent breakdown of the pool of GUS transcripts in MU7 cells. Diamide, an oxidizing agent, caused a measurable delay in the degradation of GUS transcripts in the light. The addition of dithiothreitol (DTT), a dithiol reductant, to MU7 cells in which GUS transcript levels were stabilized by DCMU induced degradation of GUS transcripts. Similarly, DTT induced a decrease in the levels of GUS transcripts when added to MU7 cells in the dark period of the light/dark cycle, a period in which GUS transcript levels normally increase. The levels of transcripts of endogenous chloroplast genes were affected by DCMU and DTT in the same direction as levels of GUS transcripts. The results suggest a regulatory role of the redox state in the degradation of chloroplast transcripts in C. reinhardtii.
Cell Division and Subsequent Radicle Protrusion in Tomato Seeds Are Inhibited by Osmotic Stress But DNA Synthesis and Formation of Microtubular Cytoskeleton Are Not
Authors: de Castro Renato D. , van Lammeren André A.M. , Groot Steven P.C. , Bino Raoul J. , Hilhorst Henk W.M. 
Published: July 2002

Abstract
We studied cell cycle events in embryos of tomato (Lycopersicon esculentum Mill. cv Moneymaker) seeds during imbibition in water and during osmoconditioning (“priming”) using both quantitative and cytological analysis of DNA synthesis and β-tubulin accumulation. Most embryonic nuclei of dry, untreated control seeds were arrested in the G1 phase of the cell cycle. This indicated the absence of DNA synthesis (the S-phase), as confirmed by the absence of bromodeoxyuridine incorporation. In addition, β-tubulin was not detected on western blots and microtubules were not present. During imbibition in water, DNA synthesis was activated in the radicle tip and then spread toward the cotyledons, resulting in an increase in the number of nuclei in G2. Concomitantly, β-tubulin accumulated and was assembled into microtubular cytoskeleton networks. Both of these cell cycle events preceded cell expansion and division and subsequent growth of the radicle through the seed coat. The activation of DNA synthesis and the formation of microtubular cytoskeleton networks were also observed throughout the embryo when seeds were osmoconditioned. However, this pre-activation of the cell cycle appeared to become arrested in the G2 phase since no mitosis was observed. The pre-activation of cell cycle events in osmoconditioned seeds appeared to be correlated with enhanced germination performance during re-imbibition in water.
Purification and Characterization of Barley Dipeptidyl Peptidase IV
Authors: Davy Anne , Thomsen Karl Kristian , Juliano Maria A. , Alves Lira C. , Svendsen Ib , Simpson David J. 
Published: July 2002

Abstract
Barley (Hordeum vulgare L.) storage proteins, which have a high content of proline (Pro) and glutamine, are cleaved by cysteine endoproteases to yield peptides with a Pro next to the N-terminal and/or C-terminal amino acid residues. A peptidase cleaving after Xaa-Pro- at the N terminus of peptides was purified from green barley malt. It was identified as a serine-type dipeptidyl peptidase (DPP), based on inhibitor studies, and the nature of the cleavage product. It is a monomeric glycoprotein with an apparent molecular mass of 105 kD (85 kD after deglycosylation), with a pI of 3.55 and a pH optimum at 7.2. Substrate specificity was determined with a series of fluorogenic peptide substrates with the general formula Xaa-Pro-AMC, where Xaa is an unspecified amino acid and AMC is 7-amino-4-methylcoumarin. The best substrates were Xaa = lysine and arginine, while the poorest were Xaa = aspartic acid, phenylalanine, and glutamic acid. TheK m values ranged from 0.071 to 8.9 μm, compared with values of 9 to 130 μmreported for mammalian DPP IVs. We discuss the possible role of DPP IV in the degradation of small Pro-containing peptides transported from the endosperm to the embryo of the germinating barley grain.
Hormone Autotrophic Growth and Differentiation Identifies Mutant Lines of Arabidopsis with Altered Cytokinin and Auxin Content or Signaling
Authors: Frank Markus , Rupp Hans-Michael , Prinsen Els , Motyka Václav , Van Onckelen Harry , Schmülling Thomas 
Published: July 2002

Abstract
We describe mutant tissue lines of Arabidopsis that are able to grow in vitro as callus on hormone-free medium. The 14 lines presented here show different hormone autotrophic differentiation behaviors that can be classified into three categories: (a) forming roots (rooty callus), (b) forming shoots or shoot-like structures (shooty callus), or (c) growing without organ formation (callus). Three fast-growing lines showed altered steady-state mRNA levels of the Cdc2 andCycD3 cell cycle genes. Three of the six rooty callus lines contained about 20- to 30-fold higher levels of auxins than wild-type callus. These and two other lines with normal auxin content showed an increased steady-state level ofIAA1 and IAA2 transcripts in the absence of exogenous auxin. Five of the six shooty callus lines had increased steady-state mRNA levels of the CKI1 gene and/or of the homeobox genes KNAT1 andSTM, suggesting that the phenotype is linked to altered cytokinin signaling. Also, one cytokinin-overproducing line with only 5% of wild-type cytokinin oxidase activity was identified. These results indicate that screening for hormone-autonomous growth identifies mutants with altered hormone content or signaling.
Coordinate Regulation of the Nuclear and Plastidic Genes Coding for the Subunits of the Heteromeric Acetyl-Coenzyme A Carboxylase
Authors: Ke Jinshan , Wen Tuan-Nan , Nikolau Basil J. , Wurtele Eve Syrkin 
Published: July 2002

Abstract
Plastidic acetyl-coenzyme A (CoA) carboxylase (ACCase) catalyzes the first committed reaction of de novo fatty acid biosynthesis. This heteromeric enzyme is composed of one plastid-coded subunit (β-carboxyltransferase) and three nuclear-coded subunits (biotin carboxy-carrier, biotin carboxylase, and α-carboxyltransferase). We report the primary structure of the Arabidopsis α-carboxyltransferase and β-carboxyltransferase subunits deduced from nucleotide sequences of the respective genes and/or cDNA. Co-immunoprecipitation experiments confirm that the α-carboxyltransferase and β-carboxyltransferase subunits are physically associated. The plant α-carboxyltransferases have gained a C-terminal domain relative to eubacteria, possibly via the evolutionary acquisition of a single exon. This C-terminal domain is divergent among plants and may have a structural function rather than being essential for catalysis. The four ACCase subunit mRNAs accumulate to the highest levels in tissues and cells that are actively synthesizing fatty acids, which are used either for membrane biogenesis in rapidly growing tissues or for oil accumulation in developing embryos. Development coordinately affects changes in the accumulation of the ACCase subunit mRNAs so that these four mRNAs maintain a constant molar stoichiometric ratio. These data indicate that the long-term, developmentally regulated expression of the heteromeric ACCase is in part controlled by a mechanism(s) that coordinately affects the steady-state concentrations of each subunit mRNA.
The Photoreduction of H2O2 bySynechococcus sp. PCC 7942 and UTEX 625
Authors: Miller Anthony G. , Hunter Kristopher J. , O'Leary Stephen J.B. , Hart Leslie J. 
Published: July 2002

Abstract
It has been claimed that the sole H2O2-scavenging system in the cyanobacteriumSynechococcus sp. PCC 7942 is a cytosolic catalase-peroxidase. We have measured in vivo activity of a light-dependent peroxidase in Synechococcus sp. PCC 7942 and UTEX 625. The addition of small amounts of H2O2 (2.5 μm) to illuminated cells caused photochemical quenching (qP) of chlorophyll fluorescence that was relieved as the H2O2 was consumed. The qP was maximal at about 50 μmH2O2 with a Michaelis constant of about 7 μm. The H2O2-dependent qP strongly indicates that photoreduction can be involved in H2O2 decomposition. Catalase-peroxidase activity was found to be almost completely inhibited by 10 μm NH2OH with no inhibition of the H2O2-dependent qP, which actually increased, presumably due to the light-dependent reaction now being the only route for H2O2-decomposition. When18O-labeled H2O2 was presented to cells in the light there was an evolution of16O2, indicative of H2 16O oxidation by PS 2 and formation of photoreductant. In the dark 18O2 was evolved from added H2 18O2 as expected for decomposition by the catalase-peroxidase. This evolution was completely blocked by NH2OH, whereas the light-dependent evolution of16O2 during H2 18O2 decomposition was unaffected.
A Matrix Metalloproteinase Gene Is Expressed at the Boundary of Senescence and Programmed Cell Death in Cucumber
Authors: Delorme Valérie G.R. , McCabe Paul F. , Kim Dae-Jae , Leaver Christopher J. 
Published: July 2002

Abstract
Cell-cell and extracellular cell matrix (ECM) interactions provide cells with information essential for controlling morphogenesis, cell-fate specification, and cell death. In animals, one of the major groups of enzymes that degrade the ECM is the matrix metalloproteinases (MMPs). Here, we report the characterization of the cucumber (Cucumis sativus L. cv Marketmore)Cs1-MMP gene encoding such an enzyme likely to play a role in plant ECM degradation. Cs1-MMP has all the hallmark motif characteristics of animal MMPs and is a pre-pro-enzyme having a signal peptide, propeptide, and zinc-binding catalytic domains. Cs1-MMP also displays functional similarities with animal MMPs. For example, it has a collagenase-like activity that can cleave synthetic peptides and type-I collagen, a major component of animal ECM. Cs1-MMP activity is completely inhibited by a hydroxamate-based inhibitor that binds at the active site of MMPs in a stereospecific manner. TheCs1-MMP gene is expressed de novo at the end stage of developmental senescence, prior to the appearance of DNA laddering in cucumber cotyledons leaf discs and male flowers. As the steady-state level of Cs1-MMP mRNA peaks late in senescence and the pro-enzyme must undergo maturation and activation, the protease is probably not involved in nutrient remobilization during senescence but may have another function. The physiological substrates for Cs1-MMP remain to be determined, but the enzyme represents a good candidate for plant ECM degradation and may be involved in programmed cell death (PCD). Our results suggest that PCD occurs only at the culmination of the senescence program or that the processes are distinct with PCD being triggered at the end of senescence.
Compression Wood-Responsive Proteins in Developing Xylem of Maritime Pine (Pinus pinasterAit.),
Authors: Plomion Christophe , Pionneau Cédric , Brach Jean , Costa Paulo , Baillères Henri 
Published: July 2002

AbstractWhen a conifer shoot is displaced from its vertical position, compression wood (CW) is formed on the under side and can eventually return the shoot to its original position. Changes in cell wall structure and chemistry associated with CW are likely to result from differential gene/protein expression. Two-dimensional polyacrylamide gel electrophoresis of differentiating xylem proteins was combined with the physical characterization of wooden samples to identify and characterize CW-responsive proteins. Differentiating xylem was harvested from a 22-year-old crooked maritime pine (Pinus pinaster Ait.) tree. Protein extracted from different samples were revealed by high-resolution silver stained two-dimensional polyacrylamide gel electrophoresis and analyzed with a computer-assisted system for single spot quantification. Growth strain (GS) measurements allowed xylem samples to be classified quantitatively from normal wood to CW. Regression of lignin and cellulose content on GS showed that an increase in the percentage of lignin and a decrease of the percentage of cellulose corresponded to increasing GS values, i.e. CW. Of the 137 studied spots, 19% were significantly associated with GS effect. Up-regulated proteins included 1-aminocyclopropane-1-carboxylate oxidase (an ethylene forming enzyme), a putative transcription factor, two lignification genes (caffeicO-methyltransferase and caffeoyl CoA-O-methyltransferase), members of theS-adenosyl-l-methionine-synthase gene family, and enzymes involved in nitrogen and carbon assimilation (glutamine synthetase and fructokinase). A clustered correlation analysis was performed to study simultaneously protein expression along a gradient of gravistimulated stressed xylem tissue. Proteins were found to form “expression clusters” that could identify: (a) Gene product under similar control mechanisms, (b) partner proteins, or (c) functional groups corresponding to specialized pathways. The possibility of obtaining regulatory correlations and anticorrelations between proteins provide us with a new category of homology (regulatory homology) in tracing functional relationships.
Origin and Seed Phenotype of Maize low phytic acid 1-1 and low phytic acid 2-1
Authors: Raboy Victor , Gerbasi Paola F. , Young Kevin A. , Stoneberg Sierra D. , Pickett Suewiya G. , Bauman Andrew T. , Murthy Pushpalatha P.N. , Sheridan William F. , Ertl David S. 
Published: July 2002

Abstract
Phytic acid (myo-inositol-1, 2, 3, 4, 5, 6-hexakisphosphate or Ins P6) typically represents approximately 75% to 80% of maize (Zea mays) seed total P. Here we describe the origin, inheritance, and seed phenotype of two non-lethal maize low phytic acid mutants, lpa1-1 and lpa2-1. The loci map to two sites on chromosome 1S. Seed phytic acid P is reduced in these mutants by 50% to 66% but seed total P is unaltered. The decrease in phytic acid P in mature lpa1-1 seeds is accompanied by a corresponding increase in inorganic phosphate (Pi). In mature lpa2-1 seed it is accompanied by increases in Pi and at least three othermyo-inositol (Ins) phosphates (and/or their respective enantiomers): d-Ins(1,2,4,5,6) P5;d-Ins (1,4,5,6) P4; andd-Ins(1,2,6) P3. In both cases the sum of seed Pi and Ins phosphates (including phytic acid) is constant and similar to that observed in normal seeds. In both mutants P chemistry appears to be perturbed throughout seed development. Homozygosity for either mutant results in a seed dry weight loss, ranging from 4% to 23%. These results indicate that phytic acid metabolism during seed development is not solely responsible for P homeostasis and indicate that the phytic acid concentration typical of a normal maize seed is not essential to seed function.
Differential Effects of Methyl Jasmonate on the Expression of the Early Light-Inducible Proteins and Other Light-Regulated Genes in Barley
Authors: Wierstra Inken , Kloppstech Klaus 
Published: July 2002

Abstract
The effects of methyl jasmonate (JA-Me) on early light-inducible protein (ELIP) expression in barley (Hordeum vulgare L. cv Apex) have been studied. Treatment of leaf segments with JA-Me induces the same symptoms as those exhibited by norflurazon bleaching, including a loss of pigments and enhanced light stress that results in increased ELIP expression under both high- and low-light conditions. The expression of both low- and high-molecular-mass ELIP families is considerably down-regulated by JA-Me at the transcript and protein levels. This repression occurs despite increased photoinhibition measurable as a massive degradation of D1 protein and a delayed recovery of photosystem II activity. In JA-Me-treated leaf segments, the decrease of the photochemical efficiency of photosystem II under high light is substantially more pronounced as compared to controls in water. The repression of ELIP expression by JA-Me is superimposed on the effect of the increased light stress that leads to enhanced ELIP expression. The fact that the reduction of ELIP transcript levels is less pronounced than those of light-harvesting complex II and small subunit of Rubisco transcripts indicates that light stress is still affecting gene expression in the presence of JA-Me. The jasmonate-induced protein transcript levels that are induced by JA-Me decline under light stress conditions.