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 41 - 60 de 50,776
41.
Molecular and Biochemical Characterization of the Selenocysteine Se-Methyltransferase Gene and Se-Methylselenocysteine Synthesis in Broccoli - Lyi, Sangbom M.; Heller, Laurence I.; Rutzke, Michael; Welch, Ross M.; Kochian, Leon V.; Li, Li
Selenium (Se) plays an indispensable role in human nutrition and has been implicated to have important health benefits, including being a cancer preventative agent. While different forms of Se vary in their anticarcinogenic efficacy, Se-methylselenocysteine (SeMSC) has been demonstrated to be one of the most effective chemopreventative compounds. Broccoli (Brassica oleracea var. italica) is known for its ability to accumulate high levels of Se with the majority of the selenoamino acids in the form of Se-methylselenocysteine. Therefore, it serves as a good model to study the regulation of SeMSC accumulation in plants. A cDNA encoding selenocysteine Se-methyltransferase, the key enzyme...
42.
Betaxanthins as Substrates for Tyrosinase. An Approach to the Role of Tyrosinase in the Biosynthetic Pathway of Betalains1 - Gandía-Herrero, Fernando; Escribano, Josefa; García-Carmona, Francisco
Tyrosinase or polyphenol oxidase (EC 1.14.18.1) is the key enzyme in melanin biosynthesis and in the enzymatic browning of fruits and vegetables. The role of tyrosinase in the secondary metabolism of plants still remains unclear, but its implication in betalain biosynthesis has been proposed. Betalains are an important class of water-soluble pigments, characteristic of plants belonging to the order Caryophyllales. In this article, the betaxanthins, tyrosine-betaxanthin (portulacaxanthin II) and dopaxanthin, are reported to be physiological substrates for tyrosinase. The direct activity of tyrosinase on selected betaxanthins is characterized in depth, and conversion of tyrosine-betaxanthin to dopaxanthin and its further oxidation...
43.
O-Acetylserine and the Regulation of Expression of Genes Encoding Components for Sulfate Uptake and Assimilation in Potato1 - Hopkins, Laura; Parmar, Saroj; B?aszczyk, Anna; Hesse, Holger; Hoefgen, Rainer; Hawkesford, Malcolm J.
cDNAs encoding a high-affinity sulfate transporter and an adenosine 5?-phosphosulfate reductase from potato (Solanum tuberosum L. cv Désirée) have been cloned and used to examine the hypothesis that sulfate uptake and assimilation is transcriptionally regulated and that this is mediated via intracellular O-acetylserine (OAS) pools. Gas chromotography coupled to mass spectrometry was used to quantify OAS and its derivative, N-acetylserine. Treatment with external OAS increased sulfate transporter and adenosine 5?-phosphosulfate reductase gene expression consistent with a model of transcriptional induction by OAS. To investigate this further, the Escherichia coli gene cysE (serine acetyltransferase EC 2.3.1.30), which synthesizes OAS, has been...
44.
Why Is Golden Rice Golden (Yellow) Instead of Red?1[w] - Schaub, Patrick; Al-Babili, Salim; Drake, Rachel; Beyer, Peter
The endosperm of Golden Rice (Oryza sativa) is yellow due to the accumulation of ?-carotene (provitamin A) and xanthophylls. The product of the two carotenoid biosynthesis transgenes used in Golden Rice, phytoene synthase (PSY) and the bacterial carotene desaturase (CRTI), is lycopene, which has a red color. The absence of lycopene in Golden Rice shows that the pathway proceeds beyond the transgenic end point and thus that the endogenous pathway must also be acting. By using TaqMan real-time PCR, we show in wild-type rice endosperm the mRNA expression of the relevant carotenoid biosynthetic enzymes encoding phytoene desaturase, ?-carotene desaturase, carotene...
45.
Increased Sedoheptulose-1,7-Bisphosphatase Activity in Transgenic Tobacco Plants Stimulates Photosynthesis and Growth from an Early Stage in Development1 - Lefebvre, Stephane; Lawson, Tracy; Zakhleniuk, Oksana V.; Lloyd, Julie C.; Raines, Christine A.
Activity of the Calvin cycle enzyme sedoheptulose-1,7-bisphosphatase (SBPase) was increased by overexpression of an Arabidopsis (Arabidopsis thaliana) cDNA in tobacco (Nicotiana tabacum) plants. In plants with increased SBPase activity, photosynthetic rates were increased, higher levels of Suc and starch accumulated during the photoperiod, and an increase in leaf area and biomass of up to 30% was also evident. Light saturated photosynthesis increased with increasing SBPase activity and analysis of CO2 response curves revealed that this increase in photosynthesis could be attributed to an increase in ribulose 1,5-bisphosphate regenerative capacity. Seedlings with increased SBPase activity had an increased leaf area at...
46.
Characterization of Arsenate Reductase in the Extract of Roots and Fronds of Chinese Brake Fern, an Arsenic Hyperaccumulator1 - Duan, Gui-Lan; Zhu, Yong-Guan; Tong, Yi-Ping; Cai, Chao; Kneer, Ralf
Root extracts from the arsenic (As) hyperaccumulating Chinese brake fern (Pteris vittata) were shown to be able to reduce arsenate to arsenite. An arsenate reductase (AR) in the fern showed a reaction mechanism similar to the previously reported Acr2p, an AR from yeast (Saccharomyces cerevisiae), using glutathione as the electron donor. Substrate specificity as well as sensitivity toward inhibitors for the fern AR (phosphate as a competitive inhibitor, arsenite as a noncompetitive inhibitor) was also similar to Acr2p. Kinetic analysis showed that the fern AR had a Michaelis constant value of 2.33 mm for arsenate, 15-fold lower than the purified...
47.
A Plant Notices Insect Egg Deposition and Changes Its Rate of Photosynthesis1 - Schröder, Roland; Forstreuter, Manfred; Hilker, Monika
Scots pine (Pinus sylvestris) is known to change its terpenoid metabolism in response to egg deposition by the sawfly Diprion pini (Hymenoptera, Diprionidae). Three days after egg deposition, parts of the pine twig adjacent to the egg-laden one are induced to emit volatiles, which attract egg parasitoids. In this study, we investigated whether egg deposition by this sawfly affects pine photosynthesis. Measurements of photosynthesis were taken from untreated control twigs and from pine twigs adjacent to egg-laden ones (i.e. systemically oviposition-induced twigs) for a period of 3 d starting after egg deposition. The net photosynthetic rate of oviposition-induced pine twigs...
48.
Cloning and Characterization of GLOSSY1, a Maize Gene Involved in Cuticle Membrane and Wax Production1[w] - Sturaro, Monica; Hartings, Hans; Schmelzer, Elmon; Velasco, Riccardo; Salamini, Francesco; Motto, Mario
The cuticle covering the aerial organs of land plants plays a protective role against several biotic and abiotic stresses and, in addition, participates in a variety of plant-insect interactions. Here, we describe the molecular cloning and characterization of the maize (Zea mays) GLOSSY1 (GL1) gene, a component of the pathway leading to cuticular wax biosynthesis in seedling leaves. The genomic and cDNA sequences we isolated differ significantly in length and in most of the coding region from those previously identified. The predicted GL1 protein includes three histidine-rich domains, the landmark of a family of membrane-bound desaturases/hydroxylases, including fatty acid-modifying enzymes....
49.
Genome-Based Examination of Chlorophyll and Carotenoid Biosynthesis in Chlamydomonas reinhardtii1[w] - Lohr, Martin; Im, Chung-Soon; Grossman, Arthur R.
The unicellular green alga Chlamydomonas reinhardtii is a particularly important model organism for the study of photosynthesis since this alga can grow heterotrophically, and mutants in photosynthesis are therefore conditional rather than lethal. The recently developed tools for genomic analyses of this organism have allowed us to identify most of the genes required for chlorophyll and carotenoid biosynthesis and to examine their phylogenetic relationships with homologous genes from vascular plants, other algae, and cyanobacteria. Comparative genome analyses revealed some intriguing features associated with pigment biosynthesis in C. reinhardtii; in some cases, there are additional conserved domains in the algal and...
50.
Antisense Suppression of a (+)-?-Cadinene Synthase Gene in Cotton Prevents the Induction of This Defense Response Gene during Bacterial Blight Infection But Not Its Constitutive Expression1[w] - Townsend, Belinda J.; Poole, Andrew; Blake, Christopher J.; Llewellyn, Danny J.
In cotton (Gossypium hirsutum) the enzyme (+)-?-cadinene synthase (CDNS) catalyzes the first committed step in the biosynthesis of cadinane-type sesquiterpenes, such as gossypol, that provide constitutive and inducible protection against pests and diseases. A cotton cDNA clone encoding CDNS (cdn1-C4) was isolated from developing embryos and functionally characterized. Southern analysis showed that CDNS genes belong to a large multigene family, of which five genomic clones were studied, including three pseudogenes and one gene that may represent another subfamily of CDNS. CDNS expression was shown to be induced in cotton infected with either the bacterial blight or verticillium wilt pathogens. Constructs...
51.
Virus Induction of Heat Shock Protein 70 Reflects a General Response to Protein Accumulation in the Plant Cytosol1 - Aparicio, Frederic; Thomas, Carole L.; Lederer, Carsten; Niu, Yan; Wang, Daowen; Maule, Andrew J.
Different cytoplasmically replicating RNA viruses were shown to induce a specific subset of heat-inducible heat shock protein 70 (HSP70) genes in Arabidopsis (Arabidopsis thaliana). To identify the inducing principle, a promoter?reporter system was developed for the facile analysis of differentially responding Arabidopsis HSP70 genes, by infiltration into Nicotiana benthamiana leaves. Through transient expression of individual viral cistrons or through deletion analysis of a viral replicon, we were unable to identify a unique inducer of HSP70. However, there was a positive correlation between the translatability of the test construct and the differential induction of HSP70. Since these data implied a lack...
52.
Recruitment of Novel Calcium-Binding Proteins for Root Nodule Symbiosis in Medicago truncatula1[W][OA] - Liu, Junqi; Miller, Susan S.; Graham, Michelle; Bucciarelli, Bruna; Catalano, Christina M.; Sherrier, D. Janine; Samac, Deborah A.; Ivashuta, Sergey; Fedorova, Maria; Matsumoto, Peter; Gantt, J. Stephen; Vance, Carroll P.
Legume rhizobia symbiotic nitrogen (N2) fixation plays a critical role in sustainable nitrogen management in agriculture and in the Earth's nitrogen cycle. Signaling between rhizobia and legumes initiates development of a unique plant organ, the root nodule, where bacteria undergo endocytosis and become surrounded by a plant membrane to form a symbiosome. Between this membrane and the encased bacteria exists a matrix-filled space (the symbiosome space) that is thought to contain a mixture of plant- and bacteria-derived proteins. Maintenance of the symbiosis state requires continuous communication between the plant and bacterial partners. Here, we show in the model legume Medicago...
53.
Xanthan Induces Plant Susceptibility by Suppressing Callose Deposition1[OA] - Yun, Maximina H.; Torres, Pablo S.; Oirdi, Mohamed El; Rigano, Luciano A.; Gonzalez-Lamothe, Rocio; Marano, María Rosa; Castagnaro, Atilio P.; Dankert, Marcelo A.; Bouarab, Kamal; Vojnov, Adrián A.
Xanthan is the major exopolysaccharide secreted by Xanthomonas spp. Despite its diverse roles in bacterial pathogenesis of plants, little is known about the real implication of this molecule in Xanthomonas pathogenesis. In this study we show that in contrast to Xanthomonas campestris pv campestris strain 8004 (wild type), the xanthan minus mutant (strain 8397) and the mutant strain 8396, which is producing truncated xanthan, fail to cause disease in both Nicotiana benthamiana and Arabidopsis (Arabidopsis thaliana) plants. In contrast to wild type, 8397 and 8396 strains induce callose deposition in N. benthamiana and Arabidopsis plants. Interestingly, treatment with xanthan but...
54.
Adenylate-Coupled Ion Movement. A Mechanism for the Control of Nodule Permeability to O2 Diffusion1[OA] - Wei, Hui; Layzell, David B.
In response to changes in phloem supply, adenylate demand, and oxygen status, legume nodules are known to exercise rapid (seconds to hours) physiological control over their permeability to oxygen diffusion. Diffusion models have attributed this permeability control to the reversible flow of water into or out of intercellular spaces. To test hypotheses on the mechanism of diffusion barrier control, nodulated soybean (Glycine max L. Merr.) plants were exposed to a range of treatments known to alter nodule O2 permeability (i.e. 10% O2, 30% O2, Ar:O2 exposure, and stem girdling) before the nodules were rapidly frozen, freeze dried, and dissected into...
55.
Mutations in the NB-ARC Domain of I-2 That Impair ATP Hydrolysis Cause Autoactivation1[OA] - Tameling, Wladimir I.L.; Vossen, Jack H.; Albrecht, Mario; Lengauer, Thomas; Berden, Jan A.; Haring, Michel A.; Cornelissen, Ben J.C.; Takken, Frank L.W.
Resistance (R) proteins in plants confer specificity to the innate immune system. Most R proteins have a centrally located NB-ARC (nucleotide-binding adaptor shared by APAF-1, R proteins, and CED-4) domain. For two tomato (Lycopersicon esculentum) R proteins, I-2 and Mi-1, we have previously shown that this domain acts as an ATPase module that can hydrolyze ATP in vitro. To investigate the role of nucleotide binding and hydrolysis for the function of I-2 in planta, specific mutations were introduced in conserved motifs of the NB-ARC domain. Two mutations resulted in autoactivating proteins that induce a pathogen-independent hypersensitive response upon expression in...
56.
Calmodulin Interacts with and Regulates the RNA-Binding Activity of an Arabidopsis Polyadenylation Factor Subunit1[OA] - Delaney, Kimberly J.; Xu, Ruqiang; Zhang, Jingxian; Li, Q. Quinn; Yun, Kil-Young; Falcone, Deane L.; Hunt, Arthur G.
The Arabidopsis (Arabidopsis thaliana) gene that encodes the probable ortholog of the 30-kD subunit of the mammalian cleavage and polyadenylation specificity factor (CPSF) is a complex one, encoding small (approximately 28 kD) and large (approximately 68 kD) polypeptides. The small polypeptide (AtCPSF30) corresponds to CPSF30 and is the focus of this study. Recombinant AtCPSF30 was purified from Escherichia coli and found to possess RNA-binding activity. Mutational analysis indicated that an evolutionarily conserved central core of AtCPSF30 is involved in RNA binding, but that RNA binding also requires a short sequence adjacent to the N terminus of the central core. AtCPSF30...
41.
