bluuebunny/crossref_metadata_2025_split huggingface dataset:
Natural Genetic Transformation byAgrobacterium rhizogenes
Authors: Limami M. Anis , Sun Li-Yan , Douat Corinne , Helgeson John , Tepfer David 
Published: July 2002

Abstract
Genetic transformation of Belgian endive (Cichorium intybus) and carrot (Daucus carota) by Agrobacterium rhizogenes resulted in a transformed phenotype, including annual flowering. Back-crossing of transformed (R1) endive plants produced a line that retained annual flowering in the absence of the other traits associated with A. rhizogenes transformation. Annualism was correlated with the segregation of a truncated transferred DNA (T-DNA) insertion. During vegetative growth, carbohydrate reserves accumulated normally in these annuals, and they were properly mobilized prior to anthesis. The effects of individual root-inducing left-hand T-DNA genes on flowering were tested in carrot, in which rolC(root locus) was the primary promoter of annualism and rolD caused extreme dwarfism. We discuss the possible adaptive significance of this attenuation of the phenotypic effects of root-inducing left-hand T-DNA.
Ectopic Expression of the Maize Homeobox GeneLiguleless3 Alters Cell Fates in the Leaf1
Authors: Muehlbauer Gary J. , Fowler John E. , Girard Lisa , Tyers Randall , Harper Lisa , Freeling Michael 
Published: July 2002

Abstract
The semidominant mutation Liguleless3-O(Lg3-O) causes a blade-to-sheath transformation at the midrib region of the maize (Zea mays L.) leaf. We isolated a full-length lg3 cDNA containing aknotted1-like family homeobox. Six Lg3-Opartial revertant alleles caused by insertion of aMutator (Mu) transposon and two deletion derivatives were isolated and used to verify that ourknotted1-like cDNA corresponds to the LG3 message. In wild-type plants the LG3 mRNA is expressed in apical regions but is not expressed in leaves. In mutant plants harboring any of three dominantlg3 alleles (Lg3-O, -Mlg, and -347), LG3 mRNA is expressed in leaf sheath tissue, indicating that the Lg3 phenotype is due to ectopic expression of the gene. The Lg3-O revertant alleles represent two classes of Lg3 phenotypes that correlate well with the level of ectopic Lg3 expression. High levels of ectopic LG3 mRNA expression results in a severe Lg3 phenotype, whereas weak ectopic Lg3 expression results in a mild Lg3 phenotype. We propose that ectopic Lg3 expression early in leaf development causes the blade-to-sheath transformation, but the level of expression determines the extent of the transformation.
Messenger RNA-Binding Properties of Nonpolysomal Ribonucleoproteins from Heat-Stressed Tomato Cells1
Authors: Stuger Rogier , Ranostaj Sigrid , Materna Tilo , Forreiter Christoph 
Published: July 2002

Abstract
Most cells experiencing heat stress reprogram their translational machinery to favor the synthesis of heat-stress proteins. Translation of other transcripts is almost completely repressed, but most untranslated messengers are not degraded. In contrast to yeast, Drosophila melanogaster, and HeLa cells, plant cells store repressed messengers in cytoplasmic nonpolysomal ribonucleoproteins (RNPs). To follow the fate of untranslated transcripts, we studied protein composition, mRNA content, and RNA-binding properties of nonpolysomal RNPs from heat-stressed tomato (Lycopersicon peruvianum) cells. Contrary to the selective interaction in vivo, RNPs isolated from tomato cells bound both stress-induced and repressed messengers, suggesting that the selection mechanism resides elsewhere. This binding was independent of a cap or a poly(A) tail. The possible role of proteasomes and heat-stress granules (HSGs) in mRNA storage is a topic of debate. We found in vitro messenger-RNA-binding activity in messenger RNP fractions free of C2-subunit-containing proteasomes and HSGs. In addition, mRNAs introduced into tobacco (Nicotiana plumbaginifolia) protoplasts were found in the cytoplasm but were not associated with HSGs.
Subcellular Localization and Speciation of Nickel in Hyperaccumulator and Non-Accumulator ThlaspiSpecies
Authors: Krämer Ute , Pickering Ingrid J. , Prince Roger C. , Raskin Ilya , Salt David E. 
Published: July 2002

Abstract
The ability of Thlaspi goesingense Hálácsy to hyperaccumulate Ni appears to be governed by its extraordinary degree of Ni tolerance. However, the physiological basis of this tolerance mechanism is unknown. We have investigated the role of vacuolar compartmentalization and chelation in this Ni tolerance. A direct comparison of Ni contents of vacuoles from leaves of T. goesingense and from the non-tolerant non-accumulator Thlaspi arvense L. showed that the hyperaccumulator accumulates approximately 2-fold more Ni in the vacuole than the non-accumulator under Ni exposure conditions that were non-toxic to both species. Using x-ray absorption spectroscopy we have been able to determine the likely identity of the compounds involved in chelating Ni within the leaf tissues of the hyperaccumulator and non-accumulator. This revealed that the majority of leaf Ni in the hyperaccumulator was associated with the cell wall, with the remaining Ni being associated with citrate and His, which we interpret as being localized primarily in the vacuolar and cytoplasm, respectively. This distribution of Ni was remarkably similar to that obtained by cell fractionation, supporting the hypothesis that in the hyperaccumulator, intracellular Ni is predominantly localized in the vacuole as a Ni-organic acid complex.
Extracellular H2O2 Induced by Oligogalacturonides Is Not Involved in the Inhibition of the Auxin-Regulated rolB Gene Expression in Tobacco Leaf Explants
Authors: Bellincampi Daniela , Dipierro Nunzio , Salvi Giovanni , Cervone Felice , De Lorenzo Giulia 
Published: July 2002

Abstract
α-1,4-Linked oligogalacturonides (OGs) inhibit auxin-regulated transcriptional activation of arolB-β-glucuronidase (GUS) gene fusion in tobacco (Nicotiana tabacum) leaf explants (D. Bellincampi, M. Cardarelli, D. Zaghi, G. Serino, G. Salvi, C. Gatz, F. Cervone, M.M. Altamura, P. Costantino, G. De Lorenzo [1996] Plant Cell 8: 477–487). In this paper we show that inhibition by OGs is very rapid, with a short lag time, and takes place even afterrolB promoter activation has initiated. OGs also induce a transient and catalase-sensitive accumulation of H2O2 in the leaf explant culture medium. OGs with a degree of polymerization from 12 to 15 are required for both the inhibition of the auxin-induced rolB-driven accumulation of GUS and the induction of H2O2accumulation. However, OG concentration for half-maximal induction of H2O2 accumulation is approximately 3-fold higher than that for half-maximal inhibition ofrolB promoter activity. The inhibition ofrolB promoter activity is not influenced by the addition of catalase or superoxide dismutase, suggesting that H2O2 and superoxide are not involved in this effect. A fungal oligo-β-glucan elicitor induces extracellular H2O2 accumulation at comparable or higher levels than those observed with OGs, but does not prevent the auxin-induced accumulation of GUS. We conclude that H2O2 produced upon treatment with OGs is not involved in the inhibition of the auxin-induced expression of therolB gene.
High-Affinity Potassium Transport in Barley Roots. Ammonium-Sensitive and -Insensitive Pathways
Authors: Santa-Marı́a Guillermo E. , Danna Cristian H. , Czibener Cecilia 
Published: July 2002

Abstract
In an attempt to understand the process mediating K+transport into roots, we examined the contribution of the NH4 +-sensitive and NH4 +-insensitive components of Rb+transport to the uptake of Rb+ in barley (Hordeum vulgare L.) plants grown in different ionic environments. We found that at low external Rb+ concentrations, an NH4 +-sensitive component dominates Rb+ uptake in plants grown in the absence of NH4 +, while Rb+ uptake preferentially occurs through an NH4 +-insensitive pathway in plants grown at high external NH4 + concentrations. A comparison of the Rb+-uptake properties observed in roots with those found in heterologous studies with yeast cells indicated that the recently cloned HvHAK1 K+ transporter may provide a major route for the NH4 +-sensitive component. HvHAK1 failed to complement the growth of a yeast strain defective in NH4 + transport, suggesting that it could not act as an NH4 + transporter. Heterologous studies also showed that the HKT1 K+/Na+-cotransporter may act as a pathway for high-affinity Rb+ transport sensitive to NH4 +. However, we found no evidence of an enhancement of Rb+ uptake into roots due to Na+addition. The possible identity of the systems contributing to the NH4 +-insensitive component in barley plants is discussed.
Detection of Expansin Proteins and Activity during Tomato Fruit Ontogeny
Authors: Rose Jocelyn K.C. , Cosgrove Daniel J. , Albersheim Peter , Darvill Alan G. , Bennett Alan B. 
Published: July 2002

Abstract
Expansins are plant proteins that have the capacity to induce extension in isolated cell walls and are thought to mediate pH-dependent cell expansion. J.K.C. Rose, H.H. Lee, and A.B. Bennett ([1997] Proc Natl Acad Sci USA 94: 5955–5960) reported the identification of an expansin gene (LeExp1) that is specifically expressed in ripening tomato (Lycopersicon esculentum) fruit where cell wall disassembly, but not cell expansion, is prominent. Expansin expression during fruit ontogeny was examined using antibodies raised to recombinant LeExp1 or a cell elongation-related expansin from cucumber (CsExp1). The LeExp1 antiserum detected expansins in extracts from ripe, but not preripe tomato fruit, in agreement with the pattern of LeExp1mRNA accumulation. In contrast, antibodies to CsExp1 cross-reacted with expansins in early fruit development and the onset of ripening, but not at a later ripening stage. These data suggest that ripening-related and expansion-related expansin proteins have distinct antigenic epitopes despite overall high sequence identity. Expansin proteins were detected in a range of fruit species and showed considerable variation in abundance; however, appreciable levels of expansin were not present in fruit of the rin or Nr tomato mutants that exhibit delayed and reduced softening. LeExp1 protein accumulation was ethylene-regulated and matched the previously described expression of mRNA, suggesting that expression is not regulated at the level of translation. We report the first detection of expansin activity in several stages of fruit development and while characteristic creep activity was detected in young and developing tomato fruit and in ripe pear, avocado, and pepper, creep activity in ripe tomato showed qualitative differences, suggesting both hydrolytic and expansin activities.
An Enhancer Trap Line Associated with a D-Class Cyclin Gene in Arabidopsis
Authors: Swaminathan Kankshita , Yang Yingzhen , Grotz Natasha , Campisi Lauren , Jack Thomas 
Published: July 2002

Abstract
In yeast and animals, cyclins have been demonstrated to be important regulators of cell cycle progression. In recent years, a large number of A-, B-, and D-class cyclins have been isolated from a variety of plant species. One class of cyclins, the D-class cyclins, is important for progression through G1 phase of the cell cycle. In Arabidopsis, four D-class cyclins have been isolated and characterized (CYCLIN-D1;1, CYCLIN-D2;1,CYCLIN-D3;1, and CYCLIN-D4;1). In this report we describe the characterization of a fifth D-class cyclin gene,CYCLIN-D3;2 (CYCD3;2), from Arabidopsis. An enhancer trap line, line 5580, contains a T-DNA insertion inCYCD3;2. Enhancer trap line 5580 exhibits expression in young vegetative and floral primordia. In line 5580, T-DNA is inserted in the first exon of the CYCD3;2 gene; in homozygous 5580 plants CYCD3;2 RNA is not detectable. Even thoughCYCD3;2 gene function is eliminated, homozygous 5580 plants do not exhibit an obvious growth or developmental phenotype. Via in situ hybridization we demonstrate that CYCD3;2 RNA is expressed in developing vegetative and floral primordia. In addition,CYCD3;2 is also capable of rescuing a yeast strain that is deficient in G1 cyclin activity.
High- and Low-Affinity Zinc Transport Systems and Their Possible Role in Zinc Efficiency in Bread Wheat
Authors: Hacisalihoglu Gokhan , Hart Jonathan J. , Kochian Leon V. 
Published: July 2002

Abstract
There is considerable variability among wheat (Triticum aestivum L.) cultivars in their ability to grow and yield well in soils that contain very low levels of available Zn. The physiological basis for this tolerance, termed Zn efficiency, is unknown. We investigated the possible role of Zn2+ influx across the root cell plasma membrane in conferring Zn efficiency by measuring short-term 65Zn2+ uptake in two contrasting wheat cultivars, Zn-efficient cv Dagdas and Zn-inefficient cv BDME-10. Plants were grown hydroponically under sufficient and deficient Zn levels, and uptake of 65Zn2+ was measured over a wide range of Zn activities (0.1 nm–80 μm). Under low-Zn conditions, cv BDME-10 displayed more severe Zn deficiency symptoms than cv Dagdas. Uptake experiments revealed the presence of two separate Zn transport systems mediating high- and low-affinity Zn influx. The low-affinity system showed apparent K m values similar to those previously reported for wheat (2–5 μm). Using chelate buffered solutions to quantify Zn2+ influx in the nanomolar activity range, we uncovered the existence of a second, high-affinity Zn transport system with apparent K m values in the range of 0.6 to 2 nm. Because it functions in the range of the low available Zn levels found in most soils, this novel high-affinity uptake system is likely to be the predominant Zn2+ uptake system. Zn2+ uptake was similar for cv Dagdas and cv BDME-10 over both the high- and low-affinity Zn2+ activity ranges, indicating that root Zn2+influx does not play a significant role in Zn efficiency.
Aquaporins Constitute a Large and Highly Divergent Protein Family in Maize
Authors: Chaumont François , Barrieu François , Wojcik Eva , Chrispeels Maarten J. , Jung Rudolf 
Published: July 2002

Abstract
Aquaporins (AQPs) are an ancient family of channel proteins that transport water and neutral solutes through a pore and are found in all eukaryotes and most prokaryotes. A comparison of the amino acid sequences and phylogenetic analysis of 31 full-length cDNAs of maize (Zea mays) AQPs shows that they comprise four different groups of highly divergent proteins. We have classified them as plasma membrane intinsic proteins (PIPs), tonoplast intrinsic proteins, Nod26-like intrinsic proteins, and small and basic intrinsic proteins. Amino acid sequence identities vary from 16% to 100%, but all sequences share structural motifs and conserved amino acids necessary to stabilize the two loops that form the aqueous pore. Most divergent are the small and basic integral proteins in which the first of the two highly conserved Asn-Pro-Ala motifs of the pore is not conserved, but is represented by alanine-proline-threonine or alanine-proline-serine. We present a model of ZmPIP1-2 based on the three-dimensional structure of mammalian AQP1. Tabulation of the number of times that the AQP sequences are found in a collection of databases that comprises about 470,000 maize cDNAs indicates that a few of the maize AQPs are very highly expressed and many are not abundantly expressed. The phylogenetic analysis supports the interpretation that the divergence of PIPs through gene duplication occurred more recently than the divergence of the members of the other three subfamilies. This study opens the way to analyze the function of the proteins in Xenopus laevis oocytes, determine the tissue specific expression of the genes, recover insertion mutants, and determine the in planta function.
Expression Profile Matrix of Arabidopsis Transcription Factor Genes Suggests Their Putative Functions in Response to Environmental Stresses[W]
Authors: Chen Wenqiong , Provart Nicholas J. , Glazebrook Jane , Katagiri Fumiaki , Chang Hur-Song , Eulgem Thomas , Mauch Felix , Luan Sheng , Zou Guangzhou , Whitham Steve A. , Budworth Paul R. , Tao Yi , Xie Zhiyi , Chen Xi , Lam Steve , Kreps Joel A. , Harper Jeffery F. , Si-Ammour Azzedine , Mauch-Mani Brigitte , Heinlein Manfred , Kobayashi Kappei , Hohn Thomas , Dangl Jeffery L. , Wang Xun , Zhu Tong 
Published: July 2002

Abstract
Numerous studies have shown that transcription factors are important in regulating plant responses to environmental stress. However, specific functions for most of the genes encoding transcription factors are unclear. In this study, we used mRNA profiles generated from microarray experiments to deduce the functions of genes encoding known and putative Arabidopsis transcription factors. The mRNA levels of 402 distinct transcription factor genes were examined at different developmental stages and under various stress conditions. Transcription factors potentially controlling downstream gene expression in stress signal transduction pathways were identified by observed activation and repression of the genes after certain stress treatments. The mRNA levels of a number of previously characterized transcription factor genes were changed significantly in connection with other regulatory pathways, suggesting their multifunctional nature. The expression of 74 transcription factor genes responsive to bacterial pathogen infection was reduced or abolished in mutants that have defects in salicylic acid, jasmonic acid, or ethylene signaling. This observation indicates that the regulation of these genes is mediated at least partly by these plant hormones and suggests that the transcription factor genes are involved in the regulation of additional downstream responses mediated by these hormones. Among the 43 transcription factor genes that are induced during senescence, 28 of them also are induced by stress treatment, suggesting extensive overlap responses to these stresses. Statistical analysis of the promoter regions of the genes responsive to cold stress indicated unambiguous enrichment of known conserved transcription factor binding sites for the responses. A highly conserved novel promoter motif was identified in genes responding to a broad set of pathogen infection treatments. This observation strongly suggests that the corresponding transcription factors play general and crucial roles in the coordinated regulation of these specific regulons. Although further validation is needed, these correlative results provide a vast amount of information that can guide hypothesis-driven research to elucidate the molecular mechanisms involved in transcriptional regulation and signaling networks in plants.
Prediction of Forming Limit Diagram Based on Damage Coupled
Kinematic-Isotropic Hardening Model Under Nonproportional Loading
Authors: Chow C. L. , Yang X. J. , Chu E. 
Published: July 2002

Abstract
Based on the theory of damage mechanics, an anisotropic damage coupled mixed isotropic-kinematic hardening plastic model for the prediction of forming limit diagram (FLD) is developed. The model includes the formulation of nonlinear anisotropic kinematic hardening. For the prediction of limit strains under nonproportional loading, a damage criterion for localized necking of sheet metals subjected to complex strain history is proposed. The model is employed to predict the FLDs of AL6111-T4 alloy. The predicted results agree well with those determined experimentally.
An Argument for Enhancement of the Current Inlet Distortion Ground
Test Practice for Aircraft Gas Turbine Engines
Authors: Davis Milt , Hale Alan , Beale Dave 
Published: July 2002

Abstract
The current high-performance aircraft development programs, and the trends in research and development activities suggest a rapidly increasing level of aircraft subsystem integration, particularly between the airframe/inlet and the propulsion system. Traditionally, these subsystems have been designed, analyzed, and tested as isolated systems. The interaction between the subsystems is modeled primarily through evaluating inlet distortion in an inlet test and simulating this distortion in engine tests via screens or similar devices. For the current test methodology, the environment that is supplied by the inlet is simulated by the imposition of total pressure profiles at the aerodynamic interface plane (AIP). Unsteady or transient variation in total pressure is generally not considered to be important. In addition, angular flow, commonly called swirl, is also not considered important enough to be simulated. In the current paper, an overview of current techniques for inlet performance, distortion characterization, and engine distortion testing is presented. A numerical study was conducted on a single high-speed rotor to qualify potential effects on stability and performance and to support the concept that dynamic distortion and swirl may have large enough effects to affect the experimentally determined stability limit. This paper reports a numerical investigation using a 3-D compression system simulation that supports the enhancement of the existing methodology to include the effects of time-dependent distortion and swirl effects. Based upon both experimental and numerical evidence, AEDC has embarked on efforts to develop inlet simulator technologies directed toward future airframe-propulsion integration requirements. This paper presents issues that require advancements in the simulation of inlet distortion techniques for direct-connect turbine engine tests.
Caspases: Enemies Within
Authors: Thornberry Nancy A. , Lazebnik Yuri 
Published: July 2002

REVIEW
Apoptosis, an evolutionarily conserved form of cell suicide, requires specialized machinery. The central component of this machinery is a proteolytic system involving a family of proteases called caspases. These enzymes participate in a cascade that is triggered in response to proapoptotic signals and culminates in cleavage of a set of proteins, resulting in disassembly of the cell. Understanding caspase regulation is intimately linked to the ability to rationally manipulate apoptosis for therapeutic gain.
The
d
-Alanine Residues of
Staphylococcus aureus
Teichoic Acids Alter the Susceptibility to Vancomycin and the Activity of Autolytic Enzymes
Authors: Peschel Andreas , Vuong Cuong , Otto Michael , Götz Friedrich 
Published: July 2002

ABSTRACT

Recently,
Staphylococcus aureus
strains with intermediate resistance to vancomycin, the antibiotic of last resort, have been described. Multiple changes in peptidoglycan turnover and structure contribute to the resistance phenotype. Here, we describe that structural changes of teichoic acids in the cell envelope have a considerable influence on the susceptibility to vancomycin and other glycopeptides.
S. aureus
cells lacking
d
-alanine esters in teichoic acids exhibited an at least threefold-increased sensitivity to glycopeptide antibiotics. Furthermore, the autolytic activity of the
d
-alanine mutant was reduced compared to the wild-type, and the mutant was more susceptible to the staphylolytic enzyme lysostaphin. Vancomycin inhibited autolysis at very high concentrations but neither in the wild-type nor in the mutant was the autolytic activity influenced in the range of the MIC. Mutant cells had a considerably higher capacity to bind vancomycin.