PubMed Central (PMC3 - NLM DTD)
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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 161 - 180 de 50,776
161.
Involvement of Phycobilisome Diffusion in Energy Quenching in Cyanobacteria1 - Joshua, Sarah; Bailey, Shaun; Mann, Nicholas H.; Mullineaux, Conrad W.
Nonphotochemical quenching (NPQ) of excitation energy is a well-established phenomenon in green plants, where it serves to protect the photosynthetic apparatus from photodamage under excess illumination. The induction of NPQ involves a change in the function of the light-harvesting apparatus, with the formation of quenching centers that convert excitation energy into heat. Recently, a comparable phenomenon was demonstrated in cyanobacteria grown under iron-starvation. Under these conditions, an additional integral membrane chlorophyll-protein, IsiA, is synthesized, and it is therefore likely that IsiA is required for NPQ in cyanobacteria. We have previously used fluorescence recovery after photobleaching to show that phycobilisomes diffuse...
162.
FesM, a Membrane Iron-Sulfur Protein, Is Required for Cyclic Electron Flow around Photosystem I and Photoheterotrophic Growth of the Cyanobacterium Synechococcus sp. PCC 70021[w] - Xu, Dongyi; Liu, Xianwei; Zhao, Jiao; Zhao, Jindong
While it is known that cyclic electron flow around photosystem I is an important pathway of photosynthetic electron transfer for converting light energy to chemical energy, some components of cyclic electron flow remain to be revealed. Here, we show that fesM, encoding a novel membrane iron-sulfur protein, is essential to cyclic electron flow in the cyanobacterium Synechococcus sp. PCC 7002. The FesM protein is predicted to have a cAMP-binding domain, an NtrC-like domain, a redox sensor motif, and an iron-sulfur (4Fe-4S) motif. Deletion of fesM (fesM-D) led to an inability for Synechococcus cells to grow in the presences of glycerol...
163.
In Vivo Respiratory Metabolism of Illuminated Leaves1 - Tcherkez, Guillaume; Cornic, Gabriel; Bligny, Richard; Gout, Elizabeth; Ghashghaie, Jaleh
Day respiration of illuminated C3 leaves is not well understood and particularly, the metabolic origin of the day respiratory CO2 production is poorly known. This issue was addressed in leaves of French bean (Phaseolus vulgaris) using 12C/13C stable isotope techniques on illuminated leaves fed with 13C-enriched glucose or pyruvate. The 13CO2 production in light was measured using the deviation of the photosynthetic carbon isotope discrimination induced by the decarboxylation of the 13C-enriched compounds. Using different positional 13C-enrichments, it is shown that the Krebs cycle is reduced by 95% in the light and that the pyruvate dehydrogenase reaction is much less...
164.
Phytic Acid Synthesis and Vacuolar Accumulation in Suspension-Cultured Cells of Catharanthus roseus Induced by High Concentration of Inorganic Phosphate and Cations1[w] - Mitsuhashi, Naoto; Ohnishi, Miwa; Sekiguchi, Yoko; Kwon, Yong-Uk; Chang, Young-Tae; Chung, Sung-Kee; Inoue, Yoshinori; Reid, Robert J.; Yagisawa, Hitoshi; Mimura, Tetsuro
We have established a new system for studying phytic acid, myo-inositol hexakisphosphate (InsP6) synthesis in suspension-cultured cells of Catharanthus. InsP6 and other intermediates of myo-inositol (Ins) phosphate metabolism were measured using an ion chromatography method. The detection limit for InsP6 was less than 50 nm, which was sufficient to analyze Ins phosphates in living cells. Synthesis of Ins phosphates was induced by incubation in high inorganic phosphate medium. InsP6 was mainly accumulated in vacuoles and was enhanced when cells were grown in high concentration of inorganic phosphates with the cations K+, Ca2+, or Zn2+. However, there was a strong tendency...
165.
Isolation of a Protein Interacting with Vfphot1a in Guard Cells of Vicia faba1 - Emi, Takashi; Kinoshita, Toshinori; Sakamoto, Koji; Mineyuki, Yoshinobu; Shimazaki, Ken-ichiro
A recent study has demonstrated that phototropins act as blue light receptors in stomatal guard cells. However, the downstream components responsible for phototropin signaling are largely unknown. In this study, using a yeast two-hybrid system, we isolated a Vicia faba protein that has a high similarity to dynein light chain in the C terminus, which interacts with Vicia faba phototropin 1a (Vfphot1a). Protein-blot and two-hybrid analyses revealed that Vfphot1a interacting protein (VfPIP) bound to the C-terminal region of Vfphot1a but did not bind to Vfphot1b. The interaction between VfPIP and Vfphot was indicated by a pull-down assay. Northern analysis revealed...
166.
Atypical Regulation of a Green Lineage-Specific B-Type Cyclin-Dependent Kinase1 - Corellou, Florence; Camasses, Alain; Ligat, Laetitia; Peaucellier, Gérard; Bouget, François-Yves
Cyclin-dependent kinases (CDKs) are the main regulators of cell cycle progression in eukaryotes. The role and regulation of canonical CDKs, such as the yeast (Saccharomyces cerevisiae) Cdc2 or plant CDKA, have been extensively characterized. However, the function of the plant-specific CDKB is not as well understood. Besides being involved in cell cycle control, Arabidopsis (Arabidopsis thaliana) CDKB would integrate developmental processes to cell cycle progression. We investigated the role of CDKB in Ostreococcus (Ostreococcus tauri), a unicellular green algae with a minimal set of cell cycle genes. In this primitive alga, at the basis of the green lineage, CDKB has...
167.
The roothairless1 Gene of Maize Encodes a Homolog of sec3, Which Is Involved in Polar Exocytosis1 - Wen, Tsui-Jung; Hochholdinger, Frank; Sauer, Michaela; Bruce, Wesley; Schnable, Patrick S.
The roothairless1 (rth1) mutant is impaired in root hair elongation and exhibits other growth abnormalities. Unicellular root hairs elongate via localized tip growth, a process mediated by polar exocytosis of secretory vesicles. We report here the cloning of the rth1 gene that encodes a sec3 homolog. In yeast (Saccharomyces cerevisiae) and mammals, sec3 is a subunit of the exocyst complex, which tethers exocytotic vesicles prior to their fusion. The cloning of the rth1 gene associates the homologs of exocyst subunits to an exocytotic process in plant development and supports the hypothesis that exocyst-like proteins are involved in plant exocytosis. Proteomic...
168.
A Sphingolipid Elicitor-Inducible Mitogen-Activated Protein Kinase Is Regulated by the Small GTPase OsRac1 and Heterotrimeric G-Protein in Rice1[w] - Lieberherr, Damien; Thao, Nguyen Phuong; Nakashima, Ayako; Umemura, Kenji; Kawasaki, Tsutomu; Shimamoto, Ko
Mitogen-activated protein kinase (MAPK) cascades are activated in plants during responses to pathogens or to pathogen-derived elicitors and mediate intracellular stress responses. Here, we show that a rice (Oryza sativa) MAPK, OsMAPK6, was posttranslationally activated in a cell culture by a sphingolipid elicitor. Suppression of OsMAPK6 expression by RNA interference resulted in a strong reduction of pathogen-induced Phe ammonia-lyase mRNA, whereas the mRNA level of another rice MAPK, OsMAPK5a, was highly increased. Silencing of a small GTPase, OsRac1, by RNA interference or loss-of-function mutation (d1) of the heterotrimeric G-protein ?-subunit gene resulted in a strong reduction of the OsMAPK6 protein...
169.
Isolation, Characterization, and Cloning of ?-l-Arabinofuranosidase Expressed during Fruit Ripening of Japanese Pear - Tateishi, Akira; Mori, Hitoshi; Watari, Junya; Nagashima, Kenji; Yamaki, Shohei; Inoue, Hiroaki
?-l-Arabinofuranosidase (?-l-arafase) was purified from fruit of Japanese pear (Pyrus pyrifolia). The enzyme solubilized from the cell wall by NaCl and Triton X-100 had the homogeneity of a single 62-kD polypeptide on SDS-PAGE after purification through the steps of hydroxyapatite, anion-exchange chromatography, and size-exclusion chromatography. A related cDNA clone was isolated (PpARF2). The transcript and related protein were detected solely in the ripening fruit corresponding to the increase of ?-l-arafase activity. Transcripts of PpARF2 were not detected in buds, leaves, roots, or shoots of the Japanese pear. The deduced amino acid sequences of PpARF2 had low identity with those of...
170.
Auxin Dynamics after Decapitation Are Not Correlated with the Initial Growth of Axillary Buds1 - Morris, Suzanne E.; Cox, Marjolein C.H.; Ross, John J.; Krisantini, Santi; Beveridge, Christine A.
One of the first and most enduring roles identified for the plant hormone auxin is the mediation of apical dominance. Many reports have claimed that reduced stem indole-3-acetic acid (IAA) levels and/or reduced basipetal IAA transport directly or indirectly initiate bud growth in decapitated plants. We have tested whether auxin inhibits the initial stage of bud release, or subsequent stages, in garden pea (Pisum sativum) by providing a rigorous examination of the dynamics of auxin level, auxin transport, and axillary bud growth. We demonstrate that after decapitation, initial bud growth occurs prior to changes in IAA level or transport in...
171.
Increasing Tolerance to Ozone by Elevating Foliar Ascorbic Acid Confers Greater Protection against Ozone Than Increasing Avoidance1 - Chen, Zhong; Gallie, Daniel R.
Ascorbic acid (Asc) is the most abundant antioxidant in plants and serves as a major contributor to the cell redox state. Exposure to environmental ozone can cause significant damage to plants by imposing conditions of oxidative stress. We examined whether increasing the level of Asc through enhanced Asc recycling would limit the deleterious effects of environmental oxidative stress. Plants overexpressing dehydroascorbate reductase (DHAR), which results in an increase in the endogenous level of Asc, were exposed to acute or chronic levels of ozone. DHAR-overexpressing plants had a lower oxidative load, a lower level of oxidative-related enzyme activities, a higher level...
172.
Comparison of Tuber Proteomes of Potato Varieties, Landraces, and Genetically Modified Lines1 - Lehesranta, Satu J.; Davies, Howard V.; Shepherd, Louise V.T.; Nunan, Naoise; McNicol, Jim W.; Auriola, Seppo; Koistinen, Kaisa M.; Suomalainen, Soile; Kokko, Harri I.; Kärenlampi, Sirpa O.
Crop improvement by genetic modification remains controversial, one of the major issues being the potential for unintended effects. Comparative safety assessment includes targeted analysis of key nutrients and antinutritional factors, but broader scale-profiling or omics methods could increase the chances of detecting unintended effects. Comparative assessment should consider the extent of natural variation and not simply compare genetically modified (GM) lines and parental controls. In this study, potato (Solanum tuberosum) proteome diversity has been assessed using a range of diverse non-GM germplasm. In addition, a selection of GM potato lines was compared to assess the potential for unintended differences in...
173.
The Maize Root Transcriptome by Serial Analysis of Gene Expression1[w] - Poroyko, V.; Hejlek, L.G.; Spollen, W.G.; Springer, G.K.; Nguyen, H.T.; Sharp, R.E.; Bohnert, H.J.
Serial Analysis of Gene Expression was used to define number and relative abundance of transcripts in the root tip of well-watered maize seedlings (Zea mays cv FR697). In total, 161,320 tags represented a minimum of 14,850 genes, based on at least two tags detected per transcript. The root transcriptome has been sampled to an estimated copy number of approximately five transcripts per cell. An extrapolation from the data and testing of single-tag identifiers by reverse transcription-PCR indicated that the maize root transcriptome should amount to at least 22,000 expressed genes. Frequency ranged from low copy number (25, 68.8%) to highly...
174.
Origin and Evolution of Kinesin-Like Calmodulin-Binding Protein1[w] - Abdel-Ghany, Salah E.; Day, Irene S.; Simmons, Mark P.; Kugrens, Paul; Reddy, Anireddy S.N.
Kinesin-like calmodulin-binding protein (KCBP), a member of the Kinesin-14 family, is a C-terminal microtubule motor with three unique domains including a myosin tail homology region 4 (MyTH4), a talin-like domain, and a calmodulin-binding domain (CBD). The MyTH4 and talin-like domains (found in some myosins) are not found in other reported kinesins. A calmodulin-binding kinesin called kinesin-C (SpKinC) isolated from sea urchin (Strongylocentrotus purpuratus) is the only reported kinesin with a CBD. Analysis of the completed genomes of Homo sapiens, Saccharomyces cerevisiae, Caenorhabditis elegans, Drosophila melanogaster, and a red alga (Cyanidioschyzon merolae 10D) did not reveal the presence of a KCBP....
175.
Mutational Decay and Age of Chloroplast and Mitochondrial Genomes Transferred Recently to Angiosperm Nuclear Chromosomes1[w] - Huang, Chun Y.; Grünheit, Nicole; Ahmadinejad, Nahal; Timmis, Jeremy N.; Martin, William
Transfers of organelle DNA to the nucleus established several thousand functional genes in eukaryotic chromosomes over evolutionary time. Recent transfers have also contributed nonfunctional plastid (pt)- and mitochondrion (mt)-derived DNA (termed nupts and numts, respectively) to plant nuclear genomes. The two largest transferred organelle genome copies are 131-kb nuptDNA in rice (Oryza sativa) and 262-kb numtDNA in Arabidopsis (Arabidopsis thaliana). These transferred copies were compared in detail with their bona fide organelle counterparts, to which they are 99.77% and 99.91% identical, respectively. No evidence for purifying selection was found in either nuclear integrant, indicating that they are nonfunctional. Mutations attributable...
176.
Profile and Analysis of Gene Expression Changes during Early Development in Germinating Spores of Ceratopteris richardii1[w] - Salmi, Mari L.; Bushart, Thomas J.; Stout, Stephen C.; Roux, Stanley J.
Analysis of an expressed sequence tag library with more than 5,000 sequences from spores of the fern Ceratopteris richardii reveals that more than 3,900 of them represent distinct genes, and almost 70% of these have significant similarity to Arabidopsis (Arabidopsis thaliana) genes. Eight genes are common between three very different dormant plant systems, Ceratopteris spores, Arabidopsis seeds, and Arabidopsis pollen. We evaluated the pattern of mRNA abundance over the first 48 h of spore development using a microarray of cDNAs representing 3,207 distinct genes of C. richardii and determined the relative levels of RNA abundance for 3,143 of these genes...
177.
Characterization of Heterologous Multigene Operons in Transgenic Chloroplasts. Transcription, Processing, and Translation1 - Quesada-Vargas, Tania; Ruiz, Oscar N.; Daniell, Henry
The first characterization of transcriptional, posttranscriptional, and translational processes of heterologous operons expressed via the tobacco (Nicotiana tabacum) chloroplast genome is reported here. Northern-blot analyses performed on chloroplast transgenic lines harboring seven different heterologous operons revealed that polycistronic mRNA was the predominant transcript produced. Despite the lack of processing of such polycistrons, large amounts of foreign protein accumulation was observed in these transgenic lines, indicating abundant translation of polycistrons. This is supported by polysome fractionation assays, which allowed detection of polycistronic RNA in lower fractions of the sucrose gradients. These results show that the chloroplast posttranscriptional machinery can indeed detect...
178.
Specificity in Ecological Interactions. Attack from the Same Lepidopteran Herbivore Results in Species-Specific Transcriptional Responses in Two Solanaceous Host Plants1[w] - Schmidt, Dominik D.; Voelckel, Claudia; Hartl, Markus; Schmidt, Silvia; Baldwin, Ian T.
Model systems have proven enormously useful in elucidating the biochemical function of plant genes. However their ecological function, having been sculpted by evolutionary forces specific to a species, may be less conserved across taxa. Responses to wounding and herbivore attack differ among plant families and are known to be mediated by oxylipin, ethylene, and systemin-signaling networks. We analyzed transcriptional responses of two native Solanaceous species to the attack of an herbivore whose elicitors are known not to be influenced by diet. With The Institute for Genomic Research 10k-cDNA potato (Solanum tuberosum) microarray, we compared the transcriptional responses of Nicotiana attenuata...
179.
Dissecting Defense-Related and Developmental Transcriptional Responses of Maize during Ustilago maydis Infection and Subsequent Tumor Formation1 - Basse, Christoph W.
Infection of maize (Zea mays) plants with the smut fungus Ustilago maydis triggers the formation of tumors on aerial parts in which the fungal life cycle is completed. A differential display screen was performed to gain insight into transcriptional changes of the host response. Some of the genes strongly up-regulated in tumors showed a pronounced developmental expression pattern with decreasing transcript levels from basal to apical shoot segments, suggesting that U. maydis has the capacity to extend the undifferentiated state of maize plants. Differentially expressed genes implicated in secondary metabolism were Bx1, involved in biosynthesis of the cyclic hydroxamic acid...
180.
A Second Kazal-Like Protease Inhibitor from Phytophthora infestans Inhibits and Interacts with the Apoplastic Pathogenesis-Related Protease P69B of Tomato1 - Tian, Miaoying; Benedetti, Brett; Kamoun, Sophien
The plant apoplast forms a protease-rich environment in which proteases are integral components of the plant defense response. Plant pathogenic oomycetes, such as the potato (Solanum tuberosum) and tomato (Lycopersicon esculentum) pathogen Phytophthora infestans, secrete a diverse family of serine protease inhibitors of the Kazal family. Among these, the two-domain EPI1 protein was shown to inhibit and interact with the pathogenesis-related protein P69B subtilase of tomato and was implicated in counter-defense. Here, we describe and functionally characterize a second extracellular protease inhibitor, EPI10, from P. infestans. EPI10 contains three Kazal-like domains, one of which was predicted to be an efficient...
161.
