TY - JOUR TI - The site of oxygen limitation in soybean nodules AU - Kuzma, M.M. AU - Winter, H. AU - Storer, P. AU - Oresnik, I. AU - Atkins, C.A. AU - Layzell, D.B. T2 - Plant Physiology AB - In legume nodules the [O2] in the infected cells limits respiration and nitrogenase activity, becoming more severe if nodules are exposed to subambient O2 levels. To identify the site of O2 limitation, adenylate pools were measured in soybean (Glycine max) nodules that were frozen in liquid N2 before being ground, lyophilized, sonicated, and separated on density gradients of nonaqueous solvents (heptane/tetrachloroethylene) to yield fractions enriched in bacteroid or plant components. In nodules maintained in air, the adenylate energy charge (AEC = [ATP + 0.5 ADP]/[ATP + ADP + AMP]) was lower in the plant compartment (0.65 +/- 0.04) than in the bacteroids (0.76 +/- 0.095), but did not change when the nodulated root system was exposed to 10% O2. In contrast, 10% O2 decreased the bacteroid AEC to 0.56 +/- 0.06, leading to the conclusion that they are the primary site of O2 limitation in nodules. To account for the low but unchanged AEC in the plant compartment and for the evidence that mitochondria are localized in O2-enriched microenvironments adjacent to intercellular spaces, we propose that steep adenylate gradients may exist between the site of ATP synthesis (and ADP use) in the mitochondria and the extra-mitochondrial sites of ATP use (and ADP production) throughout the large, infected cells. DA - 1999/// PY - 1999/// DO - 10.1104/pp.119.2.399 VL - 119 IS - 2 SP - 399-407 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0032838730&partnerID=MN8TOARS ER - TY - JOUR TI - ZYGOTIC EMBRYO CULTURE OF TAXUS CHINESIS VAR. MAIREI AND PLANT REGENERATION THROUGH ORGANOGENESIS AU - Xie, Deyu AU - Guo, Zhongchen T2 - Israel Journal of Plant Sciences AB - When different media were compared for their effect on zygotic embryo culture, DCR was found more effective than MS medium. From these embryos, adventitious bud induction was achieved by optimizing formular conditions as described in this paper. Adventitious buds were formed from calli derived from hypocotyls of germinated embryos. Finally, adventitious roots were induced and complete plantlets were obtained. DA - 1999/5/13/ PY - 1999/5/13/ DO - 10.1080/07929978.1999.10676786 VL - 47 IS - 4 SP - 287-289 J2 - Israel J Plant Sci OP - SN - 0792-9978 2223-8980 UR - http://dx.doi.org/10.1080/07929978.1999.10676786 DB - Crossref ER - TY - JOUR TI - Inactivation of toluene 2-monooxygenase in Burkholderia cepacia G4 by alkynes. T2 - Applied and environmental microbiology DA - 1999/2/1/ PY - 1999/2/1/ UR - https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/9925593/?tool=EBI ER - TY - JOUR TI - Cometabolism of chlorinated solvents by nitrifying bacteria: kinetics, substrate interactions, toxicity effects, and bacterial response T2 - Biotechnology and bioengineering AB - Pure cultures of ammonia-oxidizing bacteria, Nitrosomonas europaea, were exposed to trichloroethylene (TCE), 1,1-dichloroethylene (1,1-DCE), chloroform (CF), 1,2-dichloroethane (1,2-DCA), or carbon tetrachloride (CT), in the presence of ammonia, in a quasi-steady-state bioreactor. Estimates of enzyme kinetics constants, solvent inactivation constants, and culture recovery constants were obtained by simultaneously fitting three model curves to experimental data using nonlinear optimization techniques and an enzyme kinetics model, referred to as the inhibition, inactivation, and recovery (IIR) model, that accounts for inhibition of ammonia oxidation by the solvent, enzyme inactivation by solvent product toxicity, and respondent synthesis of new enzyme (recovery). Results showed relative enzyme affinities for ammonia monooxygenase (AMO) of 1,1-DCE approximately TCE > CT > NH(3) > CF > 1,2-DCA. Relative maximum specific substrate transformation rates were NH(3) > 1,2-DCA > CF > TCE approximately 1,1-DCE > CT (=0). The TCE, CF, and 1,1-DCE inactivated the cells, with 1,1-DCE being about three times more potent than TCE or CF. Under the conditions of these experiments, inactivating injuries caused by TCE and 1,1-DCE appeared limited primarily to the AMO enzyme, but injuries caused by CF appeared to be more generalized. The CT was not oxidized by N. europaea while 1,2-DCA was oxidized quite readily and showed no inactivation effects. Recovery capabilities were demonstrated with all solvents except CF. A method for estimating protein yield, the relationship between the transformation capacity model and the IIR model, and a condition necessary for sustainable cometabolic treatment of inactivating substrates are presented. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 54: 520-534, 1997. DA - 1999/6/1/ PY - 1999/6/1/ DO - 10.1002/(sici)1097-0290(19990620)63:6<756::aid-bit14>3.0.co;2-z UR - https://doi.org/10.1002/(sici)1097-0290(19990620)63:6<756::aid-bit14>3.0.co;2-z ER - TY - JOUR TI - Ferric Enterobactin Binding and Utilization by Neisseria gonorrhoeae AU - Carson, Susan D. Biegel AU - Klebba, Philip E. AU - Newton, Salete M. C. AU - Sparling, P. Frederick T2 - Journal of Bacteriology AB - FetA, formerly designated FrpB, an iron-regulated, 76-kDa neisserial outer membrane protein, shows sequence homology to the TonB-dependent family of receptors that transport iron into gram-negative bacteria. Although FetA is commonly expressed by most neisserial strains and is a potential vaccine candidate for both Neisseria gonorrhoeae and Neisseria meningitidis, its function in cell physiology was previously undefined. We now report that FetA functions as an enterobactin receptor. N. gonorrhoeae FA1090 utilized ferric enterobactin as the sole iron source when supplied with ferric enterobactin at approximately 10 microM, but growth stimulation was abolished when an omega (Omega) cassette was inserted within fetA or when tonB was insertionally interrupted. FA1090 FetA specifically bound 59Fe-enterobactin, with a Kd of approximately 5 microM. Monoclonal antibodies raised against the Escherichia coli enterobactin receptor, FepA, recognized FetA in Western blots, and amino acid sequence comparisons revealed that residues previously implicated in ferric enterobactin binding by FepA were partially conserved in FetA. An open reading frame downstream of fetA, designated fetB, predicted a protein with sequence similarity to the family of periplasmic binding proteins necessary for transporting siderophores through the periplasmic space of gram-negative bacteria. An Omega insertion within fetB abolished ferric enterobactin utilization without causing a loss of ferric enterobactin binding. These data show that FetA is a functional homolog of FepA that binds ferric enterobactin and may be part of a system responsible for transporting the siderophore into the cell. DA - 1999/// PY - 1999/// DO - 10.1128/jb.181.9.2895-2901.1999 VL - 181 IS - 9 SP - 2895–2901 SN - 1098-5530 0021-9193 UR - http://dx.doi.org/10.1128/jb.181.9.2895-2901.1999 ER - TY - JOUR TI - RESPONSIVE-TO-ANTAGONIST1, a Menkes/Wilson Disease–Related Copper Transporter, Is Required for Ethylene Signaling in< i> Arabidopsis AU - Hirayama, Takashi AU - Kieber, Joseph J. AU - Hirayama, Noriko AU - Kogan, Mikhail AU - Guzman, Plinio AU - Nourizadeh, Saeid AU - Alonso, Jose M. AU - Dailey, William P. AU - Dancis, Andrew AU - Ecker, Joseph R. T2 - Cell DA - 1999/// PY - 1999/// VL - 97 IS - 3 SP - 383-393 ER - TY - CHAP TI - Ethylene Perception and Response in Citrus Fruit AU - Cubells-Martinez, X. AU - Alonso, J. M. AU - Sanchez-Ballesta, M. T. AU - Granell, A. T2 - Biology and Biotechnology of the Plant Hormone Ethylene II PY - 1999/// SP - 137-143 PB - SE - ER - TY - JOUR TI - EIN2, a bifunctional transducer of ethylene and stress responses in Arabidopsis AU - Alonso, Jose M. AU - Hirayama, Takashi AU - Roman, Gregg AU - Nourizadeh, Saeid AU - Ecker, Joseph R. T2 - Science DA - 1999/// PY - 1999/// VL - 284 IS - 5423 SP - 2148-2152 ER - TY - JOUR TI - Characterization and subcellular compartmentation of recombinant 4-hydroxyphenylpyruvate dioxygenase from Arabidopsis in transgenic tobacco. T2 - Plant physiology AB - 4-Hydroxyphenylpyruvate dioxygenase (4HPPD) catalyzes the formation of homogentisate (2,5-dihydroxyphenylacetate) from p-hydroxyphenylpyruvate and molecular oxygen. In plants this enzyme activity is involved in two distinct metabolic processes, the biosynthesis of prenylquinones and the catabolism of tyrosine. We report here the molecular and biochemical characterization of an Arabidopsis 4HPPD and the compartmentation of the recombinant protein in chlorophyllous tissues. We isolated a 1508-bp cDNA with one large open reading frame of 1338 bp. Southern analysis strongly suggested that this Arabidopsis 4HPPD is encoded by a single-copy gene. We investigated the biochemical characteristics of this 4HPPD by overproducing the recombinant protein in Escherichia coli JM105. The subcellular localization of the recombinant 4HPPD in chlorophyllous tissues was examined by overexpressing its complete coding sequence in transgenic tobacco (Nicotiana tabacum), using Agrobacterium tumefaciens transformation. We performed western analyses for the immunodetection of protein extracts from purified chloroplasts and total leaf extracts and for the immunocytochemistry on tissue sections. These analyses clearly revealed that 4HPPD was confined to the cytosol compartment, not targeted to the chloroplast. Western analyses confirmed the presence of a cytosolic form of 4HPPD in cultured green Arabidopsis cells. DA - 1999/4/1/ PY - 1999/4/1/ DO - 10.1104/pp.119.4.1507 UR - https://doi.org/10.1104/pp.119.4.1507 ER - TY - JOUR TI - Fluidized bed ion exchange for improving purification of lactic acid from fermentation. AU - Raya-Tonetti, G. AU - Córdoba, P. AU - Bruno-Bárcena, J. AU - Siñeriz, F. AU - Perotti, N. T2 - Biotechnology techniques. DA - 1999/3// PY - 1999/3// DO - 10.1023/a:1008909031995 VL - 3 IS - 3 SP - 201-205 UR - http://europepmc.org/abstract/AGR/IND21990968 KW - fluidized bed KW - ion exchange KW - lactic acid ER - TY - JOUR TI - Continuous production of L(+)-lactic acid by Lactobacillus casei in two-stage systems. T2 - Applied microbiology and biotechnology DA - 1999/3// PY - 1999/3// DO - 10.1007/s002530051397 VL - 3 IS - 3 SP - 316-324 UR - http://europepmc.org/abstract/med/10222580 ER - TY - JOUR TI - Peptide antagonists of the human estrogen receptor AU - Norris, J.D. AU - Paige, L.A. AU - Christensen, D.J. AU - Chang, C.-Y. AU - Huacani, M.R. AU - Fan, D. AU - Hamilton, P.T. AU - Fowlkes, D.M. AU - McDonnell, D.P. T2 - Science AB - Estrogen receptor alpha transcriptional activity is regulated by distinct conformational states that are the result of ligand binding. Phage display was used to identify peptides that interact specifically with either estradiol- or tamoxifen-activated estrogen receptor alpha. When these peptides were coexpressed with estrogen receptor alpha in cells, they functioned as ligand-specific antagonists, indicating that estradiol-agonist and tamoxifen-partial agonist activities do not occur by the same mechanism. The ability to regulate estrogen receptor alpha transcriptional activity by targeting sites outside of the ligand-binding pocket has implications for the development of estrogen receptor alpha antagonists for the treatment of tamoxifen-refractory breast cancers. DA - 1999/// PY - 1999/// DO - 10.1126/science.285.5428.744 VL - 285 IS - 5428 SP - 744-746 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0033618510&partnerID=MN8TOARS ER - TY - JOUR TI - Estrogen receptor (ER) modulators each induce distinct conformational changes in ER   and ER   AU - Paige, L. A. AU - Christensen, D. J. AU - Gron, H. AU - Norris, J. D. AU - Gottlin, E. B. AU - Padilla, K. M. AU - Chang, C.-y. AU - Ballas, L. M. AU - Hamilton, P. T. AU - McDonnell, D. P. AU - Fowlkes, D. M. T2 - Proceedings of the National Academy of Sciences AB - Estrogen receptor (ER) modulators produce distinct tissue-specific biological effects, but within the confines of the established models of ER action it is difficult to understand why. Previous studies have suggested that there might be a relationship between ER structure and activity. Different ER modulators may induce conformational changes in the receptor that result in a specific biological activity. To investigate the possibility of modulator-specific conformational changes, we have applied affinity selection of peptides to identify binding surfaces that are exposed on the apo-ERs α and β and on each receptor complexed with estradiol or 4-OH tamoxifen. These peptides are sensitive probes of receptor conformation. We show here that ER ligands, known to produce distinct biological effects, induce distinct conformational changes in the receptors, providing a strong correlation between ER conformation and biological activity. Furthermore, the ability of some of the peptides to discriminate between different ER α and ER β ligand complexes suggests that the biological effects of ER agonists and antagonists acting through these receptors are likely to be different. DA - 1999/3// PY - 1999/3// DO - 10.1073/pnas.96.7.3999 VL - 96 IS - 7 SP - 3999-4004 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-2642544810&partnerID=MN8TOARS ER - TY - JOUR TI - Dissection of the LXXLL Nuclear Receptor-Coactivator Interaction Motif Using Combinatorial Peptide Libraries: Discovery of Peptide Antagonists of Estrogen Receptors α and β AU - Chang, Ching-yi AU - Norris, John D. AU - Grøn, Hanne AU - Paige, Lisa A. AU - Hamilton, Paul T. AU - Kenan, Daniel J. AU - Fowlkes, Dana AU - McDonnell, Donald P. T2 - Mol. Cell. Biol. AB - Recruitment of transcriptional coactivators following ligand activation is a critical step in nuclear receptor-mediated target gene expression. Upon binding an agonist, the receptor undergoes a conformational change which facilitates the formation of a specific coactivator binding pocket within the carboxyl terminus of the receptor. This permits the α-helical LXXLL motif within some coactivators to interact with the nuclear receptors. Until recently, the LXXLL motif was thought to function solely as a docking module; however, it now appears that sequences flanking the core motif may play a role in determining receptor selectivity. To address this issue, we used a combinatorial phage display approach to evaluate the role of flanking sequences in influencing these interactions. We sampled more than 108 variations of the core LXXLL motif with estradiol-activated estrogen receptor alpha (ERα) as a target and found three different classes of peptides. All of these peptides interacted with ERα in an agonist-dependent manner and disrupted ERα-mediated transcriptional activity when introduced into target cells. Using a series of ERα-mutants, we found that these three classes of peptides showed different interaction patterns from each other, suggesting that not all LXXLL motifs are the same and that receptor binding selectivity can be achieved by altering sequences flanking the LXXLL core motif. Most notable in this regard was the discovery of a peptide which, when overexpressed in cells, selectively disrupted ERβ- but not ERα-mediated reporter gene expression. This novel ERβ-specific antagonist may be useful in identifying and characterizing the ERβ-regulated process in estradiol-responsive cells. In conclusion, using a combinatorial approach to define cofactor-receptor interactions, we have clearly been able to demonstrate that not all LXXLL motifs are functionally equivalent, a finding which suggests that it may be possible to target receptor-LXXLL interactions to develop receptor-specific antagonists. DA - 1999/// PY - 1999/// DO - 10.1128/mcb.19.12.8226 VL - 19 IS - 12 SP - 8226-8239 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0033513582&partnerID=MN8TOARS ER - TY - JOUR TI - Regression equations for estimating Ilex opaca biomass components AU - Stucky, J. M. AU - Patti, H. D. AU - Shear, T. H. T2 - Castanea DA - 1999/// PY - 1999/// VL - 64 IS - 4 SP - 350 ER - TY - JOUR TI - Systematic affinities of Grubbiaceae and Hydrostachyaceae within Cornales - insights from rbcL sequences AU - Xiang, Q.-Y. T2 - Harvard Papers in Botany DA - 1999/// PY - 1999/// VL - 4 IS - 1999 SP - 527-542 ER - TY - JOUR TI - Observations on the pollination biology and flowering phenology of Texan Matelea reticulata (Engelm. Ex. A. Gray) Woods. (Asclepiadaceae) AU - Krings, A. T2 - Madrono DA - 1999/// PY - 1999/// VL - 46 IS - 3 SP - 155-158 ER - TY - JOUR TI - An annotated preliminary checklist of the dicotyledonous lianas and vines of the Las Cruces Biological Station, Costa Rica AU - Krings, A. T2 - SIDA, Contributions To Botany DA - 1999/// PY - 1999/// VL - 18 IS - 4 SP - 1247-1258 ER - TY - JOUR TI - Transposon tagging of the sulfur gene of tobacco using engineered maize Ac/Ds elements AU - Fitzmaurice, W. P. AU - Nguyen, L. V. AU - Wernsman, E. A. AU - Thompson, W. F. AU - Conkling, M. A. T2 - Genetics DA - 1999/// PY - 1999/// VL - 153 IS - 4 SP - 1919-1928 ER - TY - JOUR TI - The loss of a unique wetland in the Piedmont, North Carolina AU - Stucky, J. M. AU - Coxe, R. T2 - Castanea DA - 1999/// PY - 1999/// VL - 64 IS - 4 SP - 287 ER - TY - CHAP TI - The fates and effects of phenolic acids in a plant-microbe-soil model system AU - Blum, U. AU - Austin, M. F. AU - Shafer, S. R. T2 - Recent advances in allelopathy: I. A. science for the future A2 - F. A. Macias, J. G. C. Galindo A2 - Molinillo, J. M. G. A2 - Cutler, H. PY - 1999/// SP - 159-166 PB - Cadiz, Spain: Servicio de Publicaciones, Universidad de Cadiz SN - 8477865051 ER - TY - JOUR TI - Evidence for inhibitory allelopathic interactions involving phenolic acids in field soils: Concepts vs. an experimental model AU - Blum, Udo AU - Shafer, S. R. AU - Lehman, M. E. T2 - Critical Reviews in Plant Sciences AB - The accepted criteria for identifying allelopathic interactions in the field that have been proposed in the literature offer heuristic function, but to date have failed as a framework for research and diagnostics. If the present criteria are to be modified to make them useful empirically, their shortcomings must be identified. For this review, data from the literature and from defined model systems consisting of plants, soil, and/or microbes are used to evaluate the applicability of the accepted criteria to defined systems in which plants are responding to known allelochemicals. Based on this evaluation, modified criteria are proposed. In many respects, however, the modified criteria are as difficult to satisfy in the field as those proposed previously. The new criteria have value as a research framework because they clearly suggest that a shift in research focus to the soil environment, specifically the barrier of the rhizosphere through which allelochemicals must pass, is essential if the role of allelopathic interactions in the field is to be established. DA - 1999/// PY - 1999/// DO - 10.1080/07352689991309441 VL - 18 IS - 5 SP - 673–693 ER - TY - CHAP TI - Designing laboratory plant debris-soil bioassays: Some reflections AU - Blum, U. T2 - Principles and practices in plant ecology: Allelochemical interactions A2 - Inderjit, K. M. M. Dakshini A2 - Foy, C. CN - QK898.A43 P75 1999 PY - 1999/// SP - 17-23 PB - Boca Raton, Fla.: CRC Press ER - TY - JOUR TI - Associations of maize protein bodies with cytoskeleton, membranes, and ribosomes in the endosperm of wild type and opaque-2 mutant AU - Stankovic, B AU - Abe, S AU - Azama, K AU - Shibata, K AU - Ito, Y AU - Weidner, S AU - Davies, E T2 - ACTA PHYSIOLOGIAE PLANTARUM DA - 1999/// PY - 1999/// DO - 10.1007/s11738-999-0010-3 VL - 21 IS - 4 SP - 383-389 SN - 0137-5881 KW - cytoskeleton KW - endosperm KW - opaque-2 KW - polyribosomes KW - protein bodies KW - Zea mays ER - TY - JOUR TI - A novel gene required for cercosporin toxin resistance in the fungus Cercospora nicotianae AU - Chung, K. R. AU - Jenns, A. E. AU - Ehrenshaft, M. AU - Daub, M. E. T2 - Molecular and General Genetics DA - 1999/// PY - 1999/// DO - 10.1007/pl00008642 VL - 262 IS - 2 SP - 382-389 ER - TY - JOUR TI - Rapid and systemic accumulation of chloroplast mRNA-binding protein transcripts after flame stimulus in tomato AU - Vian, A AU - Henry-Vian, C AU - Davies, E T2 - PLANT PHYSIOLOGY AB - Abstract It has been shown that tomato (Lycopersicon esculentum) plants respond to flame wounding and electrical stimulation by a rapid (15 min) and systemic up-regulation of proteinase inhibitor (pin) genes. To find other genes having a similar expression pattern, we used subtractive cDNA screening between flamed and control plants to select clones up-regulated by flame wounding. We report the characterization of one of them, a chloroplast mRNA-binding protein encoded by a single gene and expressed preferentially in the leaves. Systemic gene expression in response to flaming in the youngest terminal leaf exhibited three distinct phases: a rapid and transient increase (5–15 min) in transcript accumulation, a decline to basal levels (15–45 min), and then a second, more prolonged increase (60–90 min). In contrast, after a mechanical wound the rapid, transient increase (5 min) was followed by a rapid decline to basal levels but no later, prolonged accumulation. In the petiole, the initial flame-wound-evoked transient increase (15 min) was followed by a continuous decline for 3 h. The nature of the wound signal(s) causing such rapid changes in transcript abundance is discussed in relation to electrical signaling, which has recently been implicated in plant responses to wounding. DA - 1999/10// PY - 1999/10// DO - 10.1104/pp.121.2.517 VL - 121 IS - 2 SP - 517-524 SN - 0032-0889 ER - TY - JOUR TI - Influence of pretreatment stresses on inhibitory effects of ferulic acid, an allelopathic phenolic acid AU - Lehman, ME AU - Blum, U T2 - JOURNAL OF CHEMICAL ECOLOGY DA - 1999/7// PY - 1999/7// DO - 10.1023/A:1020828630638 VL - 25 IS - 7 SP - 1517-1529 SN - 1573-1561 KW - allelopathy KW - ferulic acid KW - pretreatment KW - acclimation KW - tolerance KW - drought stress KW - nutrient stress KW - Cucumbis sativus KW - cucumber ER - TY - JOUR TI - Characterization of randomly-obtained matrix attachment regions (MARs) from higher plants AU - Michalowski, SM AU - Allen, GC AU - Hall, GE AU - Thompson, WF AU - Spiker, S T2 - BIOCHEMISTRY AB - Matrix attachment regions (MARs) can be operationally defined as DNA fragments that bind to the nuclear matrix. We have created a library of randomly obtained MARs from tobacco (Nicotiana tobacum) by cloning DNA fragments that co-isolate with nuclear matrixes prepared by a method involving lithium diiodosalicylate. The interactions of several of the cloned MARs with nuclear matrixes were tested by an in vitro binding assay in which genomic DNA was used as competitor. Based on this assay, the MARs were classified as strong, medium, and weak binders. Examples of each of the binding classes were further studied by in vitro binding using self- and cross-competition. Estimates of dissociation constants for several MARs ranged from 6 to 11 nM and correlated inversely with binding strength. The number of binding sites per matrix for several MARs ranged from 4 x 10(5) to 9 x 10(5) and correlated directly with binding strength. We conclude that binding strength, as we have measured it, is a function of both numbers of binding sites and affinity for the sites. The tobacco MARs were sequenced and analyzed for overall AT content, for distribution of AT-rich regions, and for the abundance of several MAR-related motifs. Previously identified MAR motifs correlate to various degrees with binding strength. Notably, the Drosophila topoisomerase II motif does not correlate with binding strength of the tobacco MARs. A newly identified motif, the "90%AT Box," correlates better with binding strength than any of the previously identified motifs we investigated. DA - 1999/9/28/ PY - 1999/9/28/ DO - 10.1021/bi991142c VL - 38 IS - 39 SP - 12795-12804 SN - 0006-2960 ER - TY - JOUR TI - Mapping and expression of a bifunctional thymidylate synthase, dihydrofolate reductase gene from maize AU - Cox, K AU - Robertson, D AU - Fites, R T2 - PLANT MOLECULAR BIOLOGY DA - 1999/12// PY - 1999/12// DO - 10.1023/A:1006324328355 VL - 41 IS - 6 SP - 733-739 SN - 0167-4412 KW - bifunctional enzymes KW - dihydrofolate reductase KW - DNA synthesis KW - endoreduplication KW - maize KW - thymidylate synthase ER - TY - JOUR TI - Evaluation of ferulic acid uptake as a measurement of allelochemical dose: Effective concentration AU - Lehman, M. E. AU - Blum, U. T2 - Journal of Chemical Ecology DA - 1999/// PY - 1999/// VL - 25 IS - 11 SP - 2589-2600 ER - TY - JOUR TI - A highly conserved sequence is a novel gene involved in de novo vitamin B6 biosynthesis AU - Ehrenshaft, M AU - Bilski, P AU - Li, MY AU - Chignell, CF AU - Daub, ME T2 - PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA AB - The Cercospora nicotianae SOR1 (singlet oxygen resistance) gene was identified previously as a gene involved in resistance of this fungus to singlet-oxygen-generating phototoxins. Although homologues to SOR1 occur in organisms in four kingdoms and encode one of the most highly conserved proteins yet identified, the precise function of this protein has, until now, remained unknown. We show that SOR1 is essential in pyridoxine (vitamin B6) synthesis in C. nicotianae and Aspergillus flavus, although it shows no homology to previously identified pyridoxine synthesis genes identified in Escherichia coli. Sequence database analysis demonstrated that organisms encode either SOR1 or E. coli pyridoxine biosynthesis genes, but not both, suggesting that there are two divergent pathways for de novo pyridoxine biosynthesis in nature. Pathway divergence appears to have occurred during the evolution of the eubacteria. We also present data showing that pyridoxine quenches singlet oxygen at a rate comparable to that of vitamins C and E, two of the most highly efficient biological antioxidants, suggesting a previously unknown role for pyridoxine in active oxygen resistance. DA - 1999/8/3/ PY - 1999/8/3/ DO - 10.1073/pnas.96.16.9374 VL - 96 IS - 16 SP - 9374-9378 SN - 0027-8424 KW - SOR1 KW - PDX1 KW - photosensitizer KW - cercosporin ER - TY - JOUR TI - Molecular and genetic analysis of transgenic rice plants expressing the maize ribosome-inactivating protein b-32 gene and the herbicide resistance bar gene AU - Kim, JK AU - Duan, XL AU - Wu, R AU - Seok, SJ AU - Boston, RS AU - Jang, IC AU - Eun, MY AU - Nahm, BH T2 - MOLECULAR BREEDING DA - 1999/// PY - 1999/// DO - 10.1023/A:1009692230725 VL - 5 IS - 2 SP - 85-94 SN - 1380-3743 KW - transgenic rice KW - bar KW - b-32 KW - proteolytic processing ER - TY - JOUR TI - Apyrase from pea stems: Isolation, purification, characterization and identification of a NTPase from the cytoskeleton fraction of pea stem tissue AU - Shibata, K AU - Morita, Y AU - Abe, S AU - Stankovic, B AU - Davies, E T2 - PLANT PHYSIOLOGY AND BIOCHEMISTRY AB - The cytoskeleton pellet from the first internode of dark-grown pea stems was disintegrated in a high salt buffer, ultracentrifuged to remove ribosomes and the post-ribosomal supernatant was applied to a heparin affinity column. Significant ATPase activity was present in the cytoskeleton fraction and this was eluted from the column at 0.6–0.7 M KOAc, in the same fractions as a 49-kDa protein (which we called B3). B3 was desalted and further purified by cation exchange column chromatography. Purified B3 catalyzed hydrolysis of ATP, CTP, GTP, TTP, UTP and ADP and thus appears to be an apyrase (ATP diphosphohydrolase, EC 3.6.1.5). Partial amino acid sequences of three major fragments were obtained by digestion of B3 by Staphylococcus aureus V8 protease (EC 3.4.21.19), and all these sequences were consistent with the previously reported amino acid sequences for pea nucleoside triphosphatase (NTPase, EC 3.6.1.15) (PIR S48859), which is thought to be an apyrase. DA - 1999/12// PY - 1999/12// DO - 10.1016/S0981-9428(99)00102-3 VL - 37 IS - 12 SP - 881-888 SN - 0981-9428 KW - apyrase KW - cytoskeleton KW - NTPase KW - Pisum sativum ER - TY - JOUR TI - Functional characterization of SOR1, a gene required for resistance to photosensitizing toxins in the fungus Cercospora nicotianae AU - Ehrenshaft, M AU - Chung, KR AU - Jenns, AE AU - Daub, ME T2 - CURRENT GENETICS DA - 1999/1// PY - 1999/1// DO - 10.1007/s002940050423 VL - 34 IS - 6 SP - 478-485 SN - 0172-8083 KW - photosensitizer resistance KW - singlet oxygen resistance KW - Cercospora spp. KW - cercosporin ER - TY - JOUR TI - Inactivation of toluene 2-monooxygenase in Burkholderia cepacia G4 by alkynes AU - Yeager, C. M. AU - Bottomley, P. J. AU - Arp, D. J. AU - Hyman, M. R. T2 - Applied and Environmental Microbiology C2 - PMC91072 DA - 1999/2// PY - 1999/2// VL - 65 IS - 2 SP - 632-639 J2 - Appl. Environ. Microbiol. LA - eng SN - 0099-2240 DB - PubMed ER - TY - JOUR TI - Geminiviruses: Models for plant DNA replication, transcription, and cell cycle regulation {review} AU - Hanley-Bowdoin, L. AU - Settlage, S. B. AU - Orozco, B. M. AU - Nagar, S. AU - Robertson, D. T2 - Critical Reviews in Plant Sciences AB - Geminiviruses have small, single-stranded DNA genomes that replicate through double-stranded intermediates in the nuclei of infected plant cells. Viral double-stranded DNA also assembles into minichromosomes and is transcribed in infected cells. Geminiviruses encode only a few proteins for their replication and transcription and rely on host enzymes for these processes. However, most plant cells, which have exited the cell cycle and undergone differentiation, do not contain the replicative enzymes necessary for viral DNA synthesis. To overcome this barrier, geminiviruses induce the accumulation of DNA replication machinery in mature plant cells, most likely by modifying cell cycle and transcriptional controls. In animals, several DNA viruses depend on host replication and transcription machinery and can alter their hosts to create an environment that facilitates efficient viral replication. Analysis of these viruses and their proteins has contributed significantly to our understanding of DNA replication, transcription, and cell cycle regulation in mammalian cells. Geminiviruses have the same potential for plant systems. Plants offer many advantages for these types of studies, including ease of transformation, well-defined cell populations and developmental programs, and greater tolerance of cell cycle perturbation and polyploidy. Our knowledge of the molecular and cellular events that mediate geminivirus infection has increased significantly during recent years. The goal of this review is to summarize recent research addressing geminivirus DNA replication and its integration with transcriptional and cell cycle regulatory processes. DA - 1999/// PY - 1999/// DO - 10.1080/07352689991309162 VL - 18 IS - 1 SP - 71-106 ER - TY - JOUR TI - Changes in cytosolic pH within Arabidopsis root columella cells play a key role in the early signaling pathway for root gravitropism AU - Scott, AC AU - Allen, NS T2 - PLANT PHYSIOLOGY AB - Ratiometric wide-field fluorescence microscopy with 1',7'- bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF)-dextran demonstrated that gravistimulation leads to rapid changes in cytoplasmic pH (pHc) in columella cells of Arabidopsis roots. The pHc of unstimulated columella cells in tiers 2 and 3, known sites of graviperception (E.B. Blancaflor, J.B. Fasano, S. Gilroy [1998] Plant Physiol 116: 213-222), was 7.22 +/- 0.02 pH units. Following gravistimulation, the magnitude and direction of pHc changes in these cells depended on their location in the columella. Cells in the lower side of tier 2 became more alkaline by 0.4 unit within 55 s of gravistimulation, whereas alkalinization of the cells on the upper side was slower (100 s). In contrast, all cells in tier 3 acidified by 0.4 pH unit within 480 s after gravistimulation. Disrupting these pHc changes in the columella cells using pHc modifiers at concentrations that do not affect root growth altered the gravitropic response. Acidifying agents, including bafilomycin A1, enhanced curvature, whereas alkalinizing agents disrupted gravitropic bending. These results imply that pHc changes in the gravisensing cells and the resultant pH gradients across the root cap are important at an early stage in the signal cascade leading to the gravitropic response. DA - 1999/12// PY - 1999/12// DO - 10.1104/pp.121.4.1291 VL - 121 IS - 4 SP - 1291-1298 SN - 1532-2548 ER - TY - JOUR TI - Transient and sustained increases in inositol 1,4,5-hisphosphate precede the differential growth response in gravistimulated maize pulvini AU - Perera, IY AU - Heilmann, I AU - Boss, WF T2 - PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA AB - The internodal maize pulvinus responds to gravistimulation with differential cell elongation on the lower side. As the site of both graviperception and response, the pulvinus is an ideal system to study how organisms sense changes in orientation. We observed a transient 5-fold increase in inositol 1,4,5-trisphosphate (IP 3 ) within 10 s of gravistimulation in the lower half of the pulvinus, indicating that the positional change was sensed immediately. Over the first 30 min, rapid IP 3 fluctuations were observed between the upper and lower halves. Maize plants require a presentation time of between 2 and 4 h before the cells on the lower side of the pulvinus are committed to elongation. After 2 h of gravistimulation, the lower half consistently had higher IP 3, and IP 3 levels on the lower side continued to increase up to ≈5-fold over basal levels before visible growth. As bending became visible after 8–10 h, IP 3 levels returned to basal values. Additionally, phosphatidylinositol 4-phosphate 5-kinase activity in the lower pulvinus half increased transiently within 10 min of gravistimulation, suggesting that the increased IP 3 production was accompanied by an up-regulation of phosphatidylinositol 4,5-bisphosphate biosynthesis. Neither IP 3 levels nor phosphatidylinositol 4-phosphate 5-kinase activity changed in pulvini halves from vertical control plants. Our data indicate the involvement of IP 3 and inositol phospholipids in both short- and long-term responses to gravistimulation. As a diffusible second messenger, IP 3 provides a mechanism to transmit and amplify the signal from the perceiving to the responding cells in the pulvinus, coordinating a synchronized growth response. DA - 1999/5/11/ PY - 1999/5/11/ DO - 10.1073/pnas.96.10.5838 VL - 96 IS - 10 SP - 5838-5843 SN - 1091-6490 ER - TY - JOUR TI - Phosphoinositide kinases and the synthesis of polyphosphoinositides in higher plant cells AU - Drobak, BK AU - Dewey, RE AU - Boss, WF T2 - INTERNATIONAL REVIEW OF CYTOLOGY - A SURVEY OF CELL BIOLOGY, VOL 189 AB - Phosphoinositides are a family of inositol-containing phospholipids which are present in all eukaryotic cells. Although in most cells these lipids, with the exception of phosphatidylinositol, constitute only a very minor proportion of total cellular lipids, they have received immense attention by researchers in the past 15-20 years. This is due to the discovery that these lipids, rather than just having structural functions, play key roles in a wide range of important cellular processes. Much less is known about the plant phosphoinositides than about their mammalian counterparts. However, it has been established that a functional phosphoinositide system exists in plant cells and it is becoming increasingly clear that inositol-containing lipids are likely to play many important roles throughout the life of a plant. It is not our intention to give an exhaustive overview of all aspects of the field, but rather we focus on the phosphoinositide kinases responsible for the synthesis of all phosphorylated forms of phosphatidylinositol. Also, we mention some of the aspects of current phosphoinositide research which, in our opinion, are most likely to provide a suitable starting point for further research into the role of phosphoinositides in plants. DA - 1999/// PY - 1999/// DO - 10.1016/S0074-7696(08)61386-8 VL - 189 SP - 95-130 SN - 0074-7696 KW - phosphatidylinositol KW - kinases KW - inositol KW - plants KW - biosynthesis KW - cell signaling KW - phosphatidylinositol transfer proteins KW - phospholipids ER - TY - JOUR TI - RNA-binding properties of in vitro expressed histidine-tagged RB69 RegA translational repressor protein AU - Allen, SV AU - Miller, ES T2 - ANALYTICAL BIOCHEMISTRY AB - To facilitate RNA-binding studies of the phage RB69 RegA translational repressor protein,regAwas configured to add six histidines to the carboxyl end of the protein.In vitrotranscription–translation from the T7 promoter on plasmid pSA1 yielded a RegA69-His6protein that binds nickel-Sepharose and elutes with 0.5 M imidazole. The system was further modified to avoid cloning and the toxic effects of RegA onEscherichia coliby the polymerase chain reaction (PCR), producing linear templates with the configuration T7 promoter-TIR-regA-His6. A translation initiation region was used that conforms to consensusE. coliand eukaryotic initiation sites and eliminates the target for RegA autogenous repression. RegA69-His6synthesized inE. coliS30 or wheat germ extracts displayed RNA-binding properties similar to wild-type RB69 RegA. Specificity of RNA binding was demonstrated byin vitrorepression of T4 gp44 and gp45 but not β-lactamase, by differential binding to poly(U)- and poly(C)-agarose, and by site-specific binding to a 23-base gene44target RNA but not to mutant44RNA. Therefore, addition of the His6tag to the C-terminus of RB69 RegA does not dramatically alter RNA binding, indicating that this region is not directly involved in site recognition. With access to several T4-like phage genomes andregAmutant sequences,in vitrosynthesis of His-tagged proteins directly from linear PCR products provides a convenient and efficient system to study RegA and other interesting RNA-binding proteins. DA - 1999/4/10/ PY - 1999/4/10/ DO - 10.1006/abio.1999.4025 VL - 269 IS - 1 SP - 32-37 SN - 1096-0309 ER - TY - JOUR TI - Dual physiological effects of antifungal sterol biosynthetic inhibitors on enzyme targets and on transcriptional regulation AU - Crowley, J. H. AU - Parks, L. W. T2 - Pesticide Science AB - For many antifungal agents, enzymes leading to ergosterol biosynthesis are primary targets. Inhibition of ergosterol biosynthesis in treated cells results in the formation of aberrant sterols, lacking one or more structural features of esgosterol. Furthermore, the total sterol levels are often higher than the total sterol amounts in non-treated cells. The ERG3 gene, encoding the sterol C-5 desaturase, was used as a model for the regulation by some antifungal agents of genes encoding enzymes in ergosterol biosynthesis. Treatment of yeast cells with three sterol biosynthetic inhibitors with different targets in the ergosterol biosynthetic pathway led to an increase in ERG3 mRNA levels. The increase in ERG3 mRNA by drug treatment correlated with a decrease in ergosterol content within the cells. No correlation was evident between ERG3 mRNA and total sterol levels, as treatment with at least one inhibitor, fenpropimorph, led to a slight increase in total sterol, while ERG3 mRNA levels decreased. Treatment of cells with fenpropimorph and ketoconazole resulted in a decrease in ergosterol as a percentage of total sterol, while lovastatin caused an increase in the ergosterol percentage. These results indicate that a second indirect effect of the antifungal sterol biosynthetic inhibitors is on transcriptional regulation. The physiology of the treated cell is affected not only by a decrease in ergosterol but also by an enhanced accumulation of defective sterols. © 1999 Society of Chemical Industry DA - 1999/// PY - 1999/// DO - 10.1002/(SICI)1096-9063(199904)55:4<393::AID-PS933>3.3.CO;2-P VL - 55 IS - 4 SP - 393-397 ER - TY - JOUR TI - Changes in phosphoinositide metabolism with days in culture affect signal transduction pathways in Galdieria sulphuraria AU - Heilmann, I AU - Perera, IY AU - Gross, W AU - Boss, WF T2 - PLANT PHYSIOLOGY AB - The metabolism of phosphatidylinositol-4,5-bisphosphate (PIP2) changed during the culture period of the thermoacidophilic red alga Galdieria sulphuraria. Seven days after inoculation, the amount of PIP2 in the cells was 910 +/- 100 pmol g-1 fresh weight; by 12 d, PIP2 levels increased to 1200 +/- 150 pmol g-1 fresh weight. In vitro assays indicated that phosphatidylinositol monophosphate (PIP) kinase specific activity increased from 75 to 230 pmol min-1 mg-1 protein between d 7 and 12. When G. sulphuraria cells were osmostimulated, transient increases of up to 4-fold could be observed in inositol-1,4,5-trisphosphate (IP3) levels within 90 s, regardless of the age of the cells. In d-12 cells, the increase in IP3 was preceded by a transient increase of up to 5-fold in specific PIP kinase activity, whereas no such increase was detected after osmostimulation of d-7 cells. The increase in PIP kinase activity before IP3 signaling in d-12 cells indicates that there is an additional pathway for regulation of phosphoinositide metabolism after stimulation other than an initial activation of phospholipase C. Also, the rapid activation of PIP2 biosynthesis in cells with already-high PIP2 levels suggests that the PIP2 present was not available for signal transduction. By comparing the response of the cells at d 7 and 12, we have identified two potentially distinct pools of PIP2. DA - 1999/4// PY - 1999/4// DO - 10.1104/pp.119.4.1331 VL - 119 IS - 4 SP - 1331-1339 SN - 0032-0889 ER - TY - JOUR TI - Anaerobic Biotransformation of Trichlorofluoroethene in Groundwater Microcosms AU - Vancheeswaran, Sanjay AU - Hyman, Michael R. AU - Semprini, Lewis T2 - Environmental Science & Technology AB - The biological reduction of trichlorofluoroethene (TCFE) was investigated in anaerobic groundwater microcosms. TCFE was reductively dehalogenated by microorganisms to produce three dichlorofluoroethene isomers, with cis-1,2-dichlorofluoroethene (c-DCFE) being the main isomer formed. Further sequential biological transformation of these compounds to mono-chlorofluoroethene isomers was incomplete and occurred at much slower rates. The rates of TCFE reduction were compared to the rates of reduction of two common chlorinated solvents, perchloroethene (PCE) and trichloroethene (TCE), when present at similar concentrations. Aqueous concentrations ranged from 7.0 to 14.0 mg/L for TCFE and from 7.5 to 15.0 mg/L for PCE and TCE. Similar rates of PCE and TCE transformation relative to TCFE were observed in single-compound tests (PCE, TCE, and TCFE in separate microcosms) and when the contaminants were present together as mixtures in the microcosms. The close similarities between the time course and kinetics of TCFE degradation and the degradation of both PCE and TCE, when present at comparable initial concentrations, suggest that TCFE could potentially be used as a benign reactive tracer to measure in-situ rates of PCE and TCE transformation in contaminated environments. DA - 1999/6/1/ PY - 1999/6/1/ DO - 10.1021/es9811952 VL - 33 IS - 12 SP - 2040-2045 J2 - Environ Sci Technol SN - 0013-936X UR - https://doi.org/10.1021/es9811952 DB - ACS Publications Y2 - 2019/2/1/ ER - TY - JOUR TI - Matrix attachment regions increase transgene expression levels and stability in transgenic rice plants and their progeny AU - Vain, P AU - Worland, B AU - Kohli, A AU - Snape, JW AU - Christou, P AU - Allen, GC AU - Thompson, WF T2 - PLANT JOURNAL AB - Summary To investigate the effect of matrix attachment regions (MARs) on transgene expression levels and stability in cereal crops, we generated 83 independent transgenic rice callus lines containing a gusA expression cassette either as a simple expression unit, or flanked with MARs from tobacco (Rb7) or yeast (ARS1). Transgenic rice plants were regenerated from these callus lines and analysed at the structural and expression levels over two generations. In the first generation (T 0 ), both Rb7 and ARS1 MARs significantly increased transgene expression levels. In the populations of plants containing MARs, we observed a significant reduction in the number of non‐expressing lines compared to the population of plants without MARs. However, variation in β‐glucuronidase (GUS) expression levels between independent lines was similar both in the presence and absence of flanking MARs. In the presence of MARs, GUS activity increased in proportion to transgene copy number up to 20 copies, but was generally reduced in lines carrying a higher copy number. In the population of plants without MARs, there was no correlation between expression level and transgene copy number. In the second generation (T 1 ), transgene expression levels were significantly correlated with those of the T 0 parents. The Rb7 MARs significantly improved the stability of transgene expression levels over two generations, and therefore appear to offer protection against transgene silencing. Our study shows that the exploitation of MARs may be an important strategy for stabilising transgene expression levels in genetically engineered cereals. DA - 1999/5// PY - 1999/5// DO - 10.1046/j.1365-313X.1999.00446.x VL - 18 IS - 3 SP - 233-242 SN - 0960-7412 ER - TY - JOUR TI - A tobacco matrix attachment region reduces the loss of transgene expression in the progeny of transgenic tobacco plants AU - Ulker, B AU - Allen, GC AU - Thompson, WF AU - Spiker, S AU - Weissinger, AK T2 - PLANT JOURNAL AB - Summary The RB7 matrix attachment region (MAR), when flanking a uidA ( GUS ) reporter gene, has been previously shown to increase uidA gene expression by 60‐fold in stably transformed tobacco suspension cell lines. We have now used the same co‐transformation procedure to determine the effect of flanking MARs on uidA gene expression in tobacco plants. The neomycin phosphotransferase selection gene and uidA reporter gene on separate plasmids were co‐transformed into seedlings by microprojectile bombardment. In primary transgenic plants, the average uidA expression in plants with MARs was twofold greater than in control plants without MARs, but there was no effect on variation of expression. GUS activity was not proportional to the number of integrated uidA transgenes over the entire range of copy numbers. However, in the lower part of the copy number range, MAR lines show a tendency for expression to increase with copy number. Transgene expression in backcross progenies of the MAR‐containing lines averaged threefold higher than in control progenies. MARs also reduced the loss of transgene expression in the BC 1 generation. Sixty‐three per cent of the 21 MAR‐containing primary transformants, but only 20% of the 14 control primary transformants, produced backcross progenies in which no loss of transgene expression was observed. These observations are discussed in the context of homology‐dependent gene silencing. DA - 1999/5// PY - 1999/5// DO - 10.1046/j.1365-313X.1999.00453.x VL - 18 IS - 3 SP - 253-263 SN - 1365-313X ER - TY - JOUR TI - Modified LDLs induce and bind to membrane ruffles on macrophages AU - Jones, N. L. AU - Allen, N. S. AU - Willingham, M. C. AU - Lewis, J. C. T2 - Anatomical Record AB - Macrophage foam cell formation in vitro requires uptake of modified low density lipoproteins (LDL) such as acetylated LDL (AcLDL) and moderately oxidized LDL (OxLDL), or beta-migrating very low density lipoprotein (βVLDL), a naturally occurring lipoprotein. Incubation of macrophages with AcLDL and OxLDL resulted in stimulation of membrane ruffle formation, while βVLDL primarily resulted in increased numbers of microvilli. Time-lapse Allen video enhanced contrast differential interference contrast (AVEC-DIC) light microscopy and correlative whole mount intermediate-voltage transmission electron microscopy (IVEM) was used to examine the dynamics of AcLDL stimulated membrane ruffling and membrane ruffle ultrastructure. Stereo 3D surface replicas confirmed that AcLDL bound to these AcLDL-induced membrane ruffles. Quantification of the plasma membrane surface area after incubation with AcLDL, βVLDL or LDL confirmed that AcLDL stimulated membrane ruffling, while βVLDL and LDL stimulated microvilli formation. These studies suggest that modified LDLs induce circular membrane ruffles and modified LDLs bind to these ligand-induced membrane ruffles. Anat Rec 255:44–56, 1999. © 1999 Wiley-Liss, Inc. DA - 1999/// PY - 1999/// DO - 10.1002/(sici)1097-0185(19990501)255:1<44::aid-ar6>3.3.co;2-z VL - 255 IS - 1 SP - 44-56 ER - TY - JOUR TI - Model system for plant cell biology: GFP imaging in living onion epidermal cells AU - Scott, A AU - Wyatt, S AU - Tsou, PL AU - Robertson, D AU - Allen, NS T2 - BIOTECHNIQUES AB - The ability to visualize organelle localization and dynamics is very useful in studying cellular physiological events. Until recently, this has been accomplished using a variety of staining methods. However, staining can give inaccurate information due to nonspecific staining, diffusion of the stain or through toxic effects. The ability to target green fluorescent protein (GFP) to various organelles allows for specific labeling of organelles in vivo. The disadvantages of GFP thus far have been the time and money involved in developing stable transformants or maintaining cell cultures for transient expression. In this paper, we present a rapid transient expression system using onion epidermal peels. We have localized GFP to various cellular compartments (including the cell wall) to illustrate the utility of this method and to visualize dynamics of these compartments. The onion epidermis has large, living, transparent cells in a monolayer, making them ideal for visualizing GFP. This method is easy and inexpensive, and it allows for testing of new GFP fusion proteins in a living tissue to determine deleterious effects and the ability to express before stable transformants are attempted. DA - 1999/6// PY - 1999/6// DO - 10.2144/99266st04 VL - 26 IS - 6 SP - 1125-+ SN - 1940-9818 ER - TY - JOUR TI - In yeast, upc2-1 confers a decrease in tolerance to LiCl and NaCl, which can be suppressed by the P-type ATPase encoded by ENA2 AU - Leak, FW AU - Tove, S AU - Parks, LW T2 - DNA AND CELL BIOLOGY AB - Wild-type yeast cells are unable to take up sterols from their growth media under aerobic conditions and are relatively resistant to monovalent cations. A yeast mutant (upc2-1) with a defect in the aerobic exclusion of sterols was found to have increased sensitivity to LiCl and NaCl. Although cation sensitivity has been reported for mutants that synthesize altered sterols, the mutant with upc2-1 continues to produce the normal sterol, ergosterol. The ENA2 gene was cloned on the basis of remediating the hypersensitivity to the monovalent cations. DA - 1999/2// PY - 1999/2// DO - 10.1089/104454999315510 VL - 18 IS - 2 SP - 133-139 SN - 1044-5498 ER -