PubMed Central (PMC3 - NLM DTD)
(2,081,148 recursos)
Archive of life sciences journal literature at the U.S. National Institutes of Health (NIH), developed and managed by NIH's National Center for Biotechnology Information (NCBI) in the National Library of Medicine (NLM).
Mostrando recursos 141 - 160 de 50,776
141.
Pectin Methylesterase, a Regulator of Pollen Tube Growth1[w] - Bosch, Maurice; Cheung, Alice Y.; Hepler, Peter K.
The apical wall of growing pollen tubes must be strong enough to withstand the internal turgor pressure, but plastic enough to allow the incorporation of new membrane and cell wall material to support polarized tip growth. These essential rheological properties appear to be controlled by pectins, which constitute the principal component of the apical cell wall. Pectins are secreted as methylesters and subsequently deesterified by the enzyme pectin methylesterase (PME) in a process that exposes acidic residues. These carboxyls can be cross-linked by calcium, which structurally rigidifies the cell wall. Here, we examine the role of PME in cell elongation...
142.
A Gibberellin-Regulated Calcineurin B in Rice Localizes to the Tonoplast and Is Implicated in Vacuole Function1 - Hwang, Yong-sic; Bethke, Paul C.; Cheong, Yong Hwa; Chang, Hur-Song; Zhu, Tong; Jones, Russell L.
Many developmental and environmental signals are transduced through changes in intracellular calcium concentrations, yet only a few calcium-binding proteins have been identified in plants. Calcineurin B-like (CBL) proteins are calcium-binding proteins that are thought to function as plant signal transduction elements. RNA profiling using a rice (Oryza sativa cv Nipponbare) oligonucleotide microarray was used to monitor gene expression in de-embryonated rice grains. This analysis showed that a putative rice CBL gene responded to gibberellic acid, but not abscisic acid, treatment. The CBL gene family in rice contains at least 10 genes and these have extensive similarity to the CBLs of...
143.
Molecular Characterization of Maize Acetylcholinesterase. A Novel Enzyme Family in the Plant Kingdom1 - Sagane, Yoshimasa; Nakagawa, Tomoyuki; Yamamoto, Kosuke; Michikawa, Soichi; Oguri, Suguru; Momonoki, Yoshie S.
Acetylcholinesterase (AChE) has been increasingly recognized in plants by indirect evidence of its activity. Here, we report purification and cloning of AChE from maize (Zea mays), thus providing to our knowledge the first direct evidence of the AChE molecule in plants. AChE was identified as a mixture of disulfide- and noncovalently linked 88-kD homodimers consisting of 42- to 44-kD polypeptides. The AChE hydrolyzed acetylthiocholine and propyonylthiocholine, but not S-butyrylthiocholine, and the AChE-specific inhibitor neostigmine bromide competitively inhibited its activity, implying that maize AChE functions in a similar manner as the animal enzyme. However, kinetic analyses indicated that maize AChE showed...
144.
Antisense Suppression of Deoxyhypusine Synthase in Tomato Delays Fruit Softening and Alters Growth and Development1 - Wang, Tzann-Wei; Zhang, Chun-Guang; Wu, Wendy; Nowack, Linda M.; Madey, Ewa; Thompson, John E.
The effects of suppressing deoxyhypusine synthase (DHS) have been examined in tomato (Solanum lycopersicum cv UCT5). DHS mediates the first of two sequential enzymatic reactions that activate eukaryotic translation initiation factor-5A (eIF-5A) by converting a conserved Lys to the unusual amino acid, deoxyhypusine. DHS protein levels were suppressed in transgenic plants by expressing the 3?-untranslated region of tomato DHS under regulation of the constitutive cauliflower mosaic virus promoter. Fruit from the transgenic plants ripened normally, but exhibited delayed postharvest softening and senescence that correlated with suppression of DHS protein levels. Northern-blot analysis indicated that all four gene family members of...
145.
A RING Domain Gene Is Expressed in Different Cell Types of Leaf Trace, Stem, and Juvenile Bundles in the Stem Vascular System of Zinnia1 - Dahiya, Preeti; Milioni, Dimitra; Wells, Brian; Stacey, Nicola; Roberts, Keith; McCann, Maureen C.
The in vitro zinnia (Zinnia elegans) mesophyll cell system, in which leaf mesophyll cells are induced to transdifferentiate into tracheary elements with high synchrony, has become an established model for studying xylogenesis. The architecture of the stem vascular system of zinnia cv Envy contains three anatomically distinct vascular bundles at different stages of development. Juvenile vascular strands of the subapical region develop into mature vascular strands with leaf trace segments and stem segments. Characteristic patterns of gene expression in juvenile, leaf trace, and stem bundles are revealed by a molecular marker, a RING domain-encoding gene, ZeRH2.1, originally isolated from a...
146.
CORKSCREW1 Defines a Novel Mechanism of Domain Specification in the Maize Shoot1 - Alexander, Debbie L.; Mellor, E. Anne; Langdale, Jane A.
In higher plants, determinate leaf primordia arise in regular patterns on the flanks of the indeterminate shoot apical meristem (SAM). The acquisition of leaf form is then a gradual process, involving the specification and growth of distinct domains within the three leaf axes. The recessive corkscrew1 (cks1) mutation of maize (Zea mays) disrupts both leaf initiation patterns in the SAM and domain specification within the mediolateral and proximodistal leaf axes. Specifically, cks1 mutant leaves exhibit multiple midribs and leaf sheath tissue differentiates in the blade domain. Such perturbations are a common feature of maize mutants that ectopically accumulate KNOTTED1-like homeobox...
147.
The Histidine Kinase Hik34 Is Involved in Thermotolerance by Regulating the Expression of Heat Shock Genes in Synechocystis1[w] - Suzuki, Iwane; Kanesaki, Yu; Hayashi, Hidenori; Hall, John J.; Simon, William J.; Slabas, Antoni R.; Murata, Norio
Histidine kinases (Hiks) in Synechocystis sp. PCC 6803 are involved in the transduction of signals associated with various kinds of environmental stress. To examine the potential role in thermotolerance of Hiks, we used genome microarray analysis to screen a Hik knockout library for mutations that affected the expression of genes for heat shock proteins. Mutation of the hik34 gene enhanced the levels of transcripts of a number of heat shock genes, including htpG and groESL1. Overexpression of the hik34 gene repressed the expression of these heat shock genes. In addition, the cells with a mutant gene for Hik34 (?Hik34 cells)...
148.
Tocopherols Protect Synechocystis sp. Strain PCC 6803 from Lipid Peroxidation1 - Maeda, Hiroshi; Sakuragi, Yumiko; Bryant, Donald A.; DellaPenna, Dean
Tocopherols (vitamin E) are lipid-soluble antioxidants synthesized only by photosynthetic eukaryotes and some cyanobacteria, and have been assumed to play important roles in protecting photosynthetic membranes from oxidative stress. To test this hypothesis, tocopherol-deficient mutants of Synechocystis sp. strain PCC 6803 (slr1736 and slr1737 mutants) were challenged with a series of reactive oxygen species-generating and lipid peroxidation-inducing chemicals in combination with high-light (HL) intensity stress. The tocopherol-deficient mutants and wild type were indistinguishable in their growth responses to HL in the presence and absence of superoxide and singlet oxygen-generating chemicals. However, the mutants showed enhanced sensitivity to linoleic or linolenic...
149.
Functional Analysis of Arabidopsis Ethylene-Responsive Element Binding Protein Conferring Resistance to Bax and Abiotic Stress-Induced Plant Cell Death1 - Ogawa, Taro; Pan, Ling; Kawai-Yamada, Maki; Yu, Li-Hua; Yamamura, Saburo; Koyama, Tomotsugu; Kitajima, Sakihito; Ohme-Takagi, Masaru; Sato, Fumihiko; Uchimiya, Hirofumi
Arabidopsis (Arabidopsis thaliana) ethylene-responsive element binding protein (AtEBP) gene was isolated as a suppressor of Bax-induced cell death by functional screening in yeast (Saccharomyces cerevisiae). To further examine the cell death suppressive action of AtEBP in plant cells, we established transgenic tobacco (Nicotiana tabacum) plants overexpressing AtEBP as well as transgenic tobacco plants ectopically expressing mouse Bax protein under a dexamethasone-inducible promoter. We prepared the crosses of the selective lines of each transgenic plant, which were evaluated in terms of cell death suppression activity. Results indicate that AtEBP suppressed Bax-induced cell death in tobacco plants, an action also associated with...
150.
Interacting Proteins and Differences in Nuclear Transport Reveal Specific Functions for the NAP1 Family Proteins in Plants1 - Dong, Aiwu; Liu, Ziqiang; Zhu, Yan; Yu, Fang; Li, Ziyu; Cao, Kaiming; Shen, Wen-Hui
Nucleosome assembly protein 1 (NAP1) is conserved from yeast to human and facilitates the in vitro assembly of nucleosomes as a histone chaperone. Inconsistent with their proposed function in the nucleus, however, many NAP1 proteins had been reported to localize in the cytoplasm. We investigated the subcellular localization of tobacco (Nicotiana tabacum) and rice (Oryza sativa) NAP1 family proteins first by identification of interacting partners and by direct examination of the localization of green fluorescent protein-tagged proteins. Through treatment of tobacco cells with leptomycin B and mutagenesis of nuclear export signal, we demonstrated that Nicta;NAP1;1 and Orysa;NAP1;1 shuttle between the...
151.
Compilation of mRNA Polyadenylation Signals in Arabidopsis Revealed a New Signal Element and Potential Secondary Structures1[w] - Loke, Johnny C.; Stahlberg, Eric A.; Strenski, David G.; Haas, Brian J.; Wood, Paul Chris; Li, Qingshun Quinn
Using a novel program, SignalSleuth, and a database containing authenticated polyadenylation [poly(A)] sites, we analyzed the composition of mRNA poly(A) signals in Arabidopsis (Arabidopsis thaliana), and reevaluated previously described cis-elements within the 3?-untranslated (UTR) regions, including near upstream elements and far upstream elements. As predicted, there are absences of high-consensus signal patterns. The AAUAAA signal topped the near upstream elements patterns and was found within the predicted location to only approximately 10% of 3?-UTRs. More importantly, we identified a new set, named cleavage elements, of poly(A) signals flanking both sides of the cleavage site. These cis-elements were not previously revealed...
152.
Localized Hormone Fluxes and Early Haustorium Development in the Hemiparasitic Plant Triphysaria versicolor1 - Tomilov, Alexey A.; Tomilova, Natalia B.; Abdallah, Ibrahim; Yoder, John I.
Perhaps the most obvious phenotypes associated with chemical signaling between plants are manifested by parasitic species of Orobanchaceae. The development of haustoria, invasive root structures that allow hemiparasitic plants to transition from autotrophic to heterotrophic growth, is rapid, highly synchronous, and readily observed in vitro. Haustorium development is initiated in aseptic roots of the facultative parasite Triphysaria versicolor when exposed to phenolic molecules associated with host root exudates and rhizosphere bioactivity. Morphological features of early haustorium ontogeny include rapid cessation of root elongation, expansion, and differentiation of epidermal cells into haustorial hairs, and cortical cell expansion. These developmental processes were...
153.
Systemic Acquired Tolerance to Virulent Bacterial Pathogens in Tomato1 - Block, Anna; Schmelz, Eric; O'Donnell, Phillip J.; Jones, Jeffrey B.; Klee, Harry J.
Recent studies on the interactions between plants and pathogenic microorganisms indicate that the processes of disease symptom development and pathogen growth can be uncoupled. Thus, in many instances, the symptoms associated with disease represent an active host response to the presence of a pathogen. These host responses are frequently mediated by phytohormones. For example, ethylene and salicylic acid (SA) mediate symptom development but do not influence bacterial growth in the interaction between tomato (Lycopersicon esculentum) and virulent Xanthomonas campestris pv vesicatoria (Xcv). It is not apparent why extensive tissue death is integral to a defense response if it does not...
154.
Differences in Cell Death Induction by Phytophthora Elicitins Are Determined by Signal Components Downstream of MAP Kinase Kinase in Different Species of Nicotiana and Cultivars of Brassica rapa and Raphanus sativus[w] - Takemoto, Daigo; Hardham, Adrienne R.; Jones, David A.
Elicitins are small, secreted proteins produced by species of the plant-pathogenic oomycete Phytophthora. They induce hypersensitive cell death in most Nicotiana species and in some cultivars of Brassica rapa and Raphanus sativus. In this study, two true-breeding Fast Cycling B. rapa lines were established that showed severe necrosis (line 7-R) or no visible response (line 18-NR) after treatment with elicitin. Unexpectedly, microscopic examination revealed localized cell death in line 18-NR plants, and expression levels of various defense-marker genes were comparable in both lines. These results suggested that both responsive and nonresponsive plants responded to elicitin but differed in the extent...
155.
Vitamin B1 Functions as an Activator of Plant Disease Resistance1 - Ahn, Il-Pyung; Kim, Soonok; Lee, Yong-Hwan
Vitamin B1 (thiamine) is an essential nutrient for humans. Vitamin B1 deficiency causes beriberi, which disturbs the central nervous and circulatory systems. In countries in which rice (Oryza sativa) is a major food, thiamine deficiency is prevalent because polishing of rice removes most of the thiamine in the grain. We demonstrate here that thiamine, in addition to its nutritional value, induces systemic acquired resistance (SAR) in plants. Thiamine-treated rice, Arabidopsis (Arabidopsis thaliana), and vegetable crop plants showed resistance to fungal, bacterial, and viral infections. Thiamine treatment induces the transient expression of pathogenesis-related (PR) genes in rice and other plants. In...
156.
Fatty Acid Hydroperoxides and H2O2 in the Execution of Hypersensitive Cell Death in Tobacco Leaves1[w] - Montillet, Jean-Luc; Chamnongpol, Sangpen; Rustérucci, Christine; Dat, James; van de Cotte, Brigitte; Agnel, Jean-Pierre; Battesti, Christine; Inzé, Dirk; Van Breusegem, Frank; Triantaphylidès, Christian
We initially compared lipid peroxidation profiles in tobacco (Nicotiana tabacum) leaves during different cell death events. An upstream oxylipin assay was used to discriminate reactive oxygen species (ROS)-mediated lipid peroxidation from 9- and 13-lipoxygenase (LOX)-dependent lipid peroxidation. Free radical-mediated membrane peroxidation was measured during H2O2-dependent cell death in leaves of catalase-deficient plants. Taking advantage of these transgenic plants, we demonstrate that, under light conditions, H2O2 plays an essential role in the execution of cell death triggered by an elicitor, cryptogein, which provokes a similar ROS-mediated lipid peroxidation. Under dark conditions, however, cell death induction by cryptogein was independent of H2O2...
157.
Thermodynamic Battle for Photosynthate Acquisition between Sieve Tubes and Adjoining Parenchyma in Transport Phloem1 - Hafke, Jens B.; van Amerongen, Jan-Kees; Kelling, Frits; Furch, Alexandra C.U.; Gaupels, Frank; van Bel, Aart J.E.
In transport phloem, photoassimilates escaping from the sieve tubes are released into the apoplasmic space between sieve element (SE)/companion cell (CC) complexes (SE/CCs) and phloem parenchyma cells (PPCs). For uptake respective retrieval, PPCs and SE/CCs make use of plasma membrane translocators energized by the proton motive force (PMF). Their mutual competitiveness, which essentially determines the amount of photoassimilates translocated through the sieve tubes, therefore depends on the respective PMFs. We measured the components of the PMF, membrane potential and ?pH, of SE/CCs and PPCs in transport phloem. Membrane potentials of SE/CCs and PPCs in tissue slices as well as in...
158.
Water Uptake and Distribution in Germinating Tobacco Seeds Investigated in Vivo by Nuclear Magnetic Resonance Imaging1[w] - Manz, Bertram; Müller, Kerstin; Kucera, Birgit; Volke, Frank; Leubner-Metzger, Gerhard
The regulation of water uptake of germinating tobacco (Nicotiana tabacum) seeds was studied spatially and temporally by in vivo 1H-nuclear magnetic resonance (NMR) microimaging and 1H-magic angle spinning NMR spectroscopy. These nondestructive state-of-the-art methods showed that water distribution in the water uptake phases II and III is inhomogeneous. The micropylar seed end is the major entry point of water. The micropylar endosperm and the radicle show the highest hydration. Germination of tobacco follows a distinct pattern of events: rupture of the testa is followed by rupture of the endosperm. Abscisic acid (ABA) specifically inhibits endosperm rupture and phase III water...
159.
Purification and Characterization of Adenosine Diphosphate Glucose Pyrophosphorylase from Maize/Potato Mosaics1 - Boehlein, Susan K.; Sewell, Aileen K.; Cross, Joanna; Stewart, Jon D.; Hannah, L. Curtis
Adenosine diphosphate glucose pyrophosphorylase (AGPase) catalyzes a rate-limiting step in starch biosynthesis. The reaction produces ADP-glucose and pyrophosphate from glucose-1-P and ATP. Investigations from a number of laboratories have shown that alterations in allosteric properties as well as heat stability of this enzyme have dramatic positive effects on starch synthesis in the potato (Solanum tuberosum) tuber and seeds of important cereals. Here, we report the characterization of purified recombinant mosaic AGPases derived from protein motifs normally expressed in the maize (Zea mays) endosperm and the potato tuber. These exhibit properties that should be advantageous when expressed in plants. We also...
160.
Molecular Cloning of a ?-Galactosidase from Radish That Specifically Hydrolyzes ?-(1?3)- and ?-(1?6)-Galactosyl Residues of Arabinogalactan Protein1 - Kotake, Toshihisa; Dina, Soraya; Konishi, Tomoyuki; Kaneko, Satoshi; Igarashi, Kiyohiko; Samejima, Masahiro; Watanabe, Yoko; Kimura, Kazumasa; Tsumuraya, Yoichi
A basic ?-galactosidase with high specificity toward ?-(1?3)- and ?-(1?6)-galactosyl residues was cloned from radish (Raphanus sativus) plants by reverse transcription-PCR. The gene, designated RsBGAL1, contained an open reading frame consisting of 2,532 bp (851 amino acids). It is expressed in hypocotyls and young leaves. RsBGAL1 was highly similar to ?-galactosidases having exo-?-(1?4)-galactanase activity found in higher plants and belongs to family 35 of the glycosyl hydrolases. Recombinant RsBGAL1 was expressed in Pichia pastoris and purified to homogeneity. The recombinant enzyme specifically hydrolyzed ?-(1?3)- and ?-(1?6)-galactooligosaccharides, the same substrates as the native enzyme isolated from radish seeds (Sekimata et al.,...
141.
