bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modulation of Cyclin Transcript Levels in Cultured Cells of Arabidopsis thaliana
Authors: Fuerst RAUA. , Soni R. , Murray JAH. , Lindsey K. 
Published: July 2002

Abstract
Previous studies on the cell cycle of Arabidopsis thaliana have been hindered by the lack of synchronous cell culture systems. We have used liquid callus cultures and a cycloheximide-synchronized suspension culture of Arabidopsis to investigate changes in cyclin transcript levels in response to exogenous auxin, cytokinin, and nutrients, and during the cell cycle. CYCD1 ([delta]1) transcript was virtually undetectable in liquid-cultured callus or suspension-culture cells. CYCD2 ([delta]2) transcript levels were largely unaffected by the readdition of phytohormones or nitrate to the growth medium, and remained constant throughout the cell cycle in suspension-culture cells. CYCD3 ([delta]3) transcript levels were strongly dependent on nitrate, and were induced at the G1/S transition following phytohormone readdition. In synchronized suspension-culture cells, CYCD3 transcript accumulated during the S phase, and remained constant thereafter. These results support the hypothesis that D cyclins function as part of the cellular machinery that integrates diverse signals impinging upon commitment to cell division. In synchronized cells transcripts of the mitotic cyclins CYC1, CYC2, and CYC3 reached a maximum with peak mitotic index, but CYC3 transcript levels increased earlier than those of CYC1 or CYC2. The kinetics of accumulation of CYC transcript levels support their classification as A-type (CYC3) and B-type (CYC1 and CYC2) cyclins, respectively.
Differential Expression of the Multigene Family Encoding the Soybean Mitochondrial Alternative Oxidase
Authors: Finnegan P. M. , Whelan J. , Millar A. H. , Zhang Q. , Smith M. K. , Wiskich J. T. , Day D. A. 
Published: July 2002

Abstract
The alternative oxidase (AOX) of the soybean (Glycine max L.) inner mitochondrial membrane is encoded by a multigene family (Aox) with three known members. Here, the Aox2 and Aox3 primary translation products, deduced from cDNA analysis, were found to be 38.1 and 36.4 kD, respectively. Direct N-terminal sequencing of partially purified AOX from cotyledons demonstrates that the mature proteins are 31.8 and 31.6 kD, respectively, implying that processing occurs upon import of these proteins into the mitochondrion. Sequence comparisons show that the processing of plant AOX proteins occurs at a characteristic site and that the AOX2 and AOX3 proteins are more similar to one another than to other AOX proteins, including soybean AOX1. Transcript analysis using a polymerase chain reaction-based assay in conjunction with immunoblot experiments indicates that soybean Aox genes are differentially expressed in a tissue-dependent manner. Moreover, the relative abundance of both Aox2 transcripts and protein in cotyledons increase upon greening of dark-grown seedlings. These results comprehensively explain the multiple AOX-banding patterns observed on immunoblots of mitochondrial proteins isolated from various soybean tissues by matching protein bands with gene products.
Sex Determination in Dioecious Silene Iatifolia (Effects of the Y Chromosome and the Parasitic Smut Fungus (Ustilago violacea) on Gene Expression during Flower Development)
Authors: Scutt C. P. , Li Y. , Robertson S. E. , Willis M. E. , Gilmartin P. M. 
Published: July 2002

Abstract
We have embarked on a molecular cloning approach to the investigation of sex determination in Silene Iatifolia Poiret, a dioecious plant species with morphologically distinguishable sex chromosomes. One of our key objectives was to define a range of genes that are up-regulated in male plants in response to Y chromosome sex-determination genes. Here we present the characterization of eight male-specific cDNA sequences and classify these according to their expression dynamics to provide a range of molecular markers for dioecious male flower development. Genetically female S. latifolia plants undergo a partial sex reversal in response to infection by the parasitic smut fungus Ustilago violacea. This phenomenon has been exploited in these studies; male-specific cDNAs have been further categorized as inducible or noninducible in female plants by smut fungus infection. Analysis of the organ-specific expression of male-specific probes in male and female flowers has also identified a gene that is regulated in a sex-specific manner in nonreproductive floral tissues common to both male and female plants. This observation provides, to our knowledge, the first molecular marker for dominant effects of the Y chromosome in nonreproductive floral organs.
Rapid and Transient Induction of a Parsley Microsomal [delta]12 Fatty Acid Desaturase mRNA by Fungal Elicitor
Authors: Kirsch C. , Hahlbrock K. , Somssich I. E. 
Published: July 2002

Abstract
Treatment of cultured parsley (Petroselinum crispum L.) cells with a structurally defined peptide elicitor (Pep25) of fungal origin has previously been shown to cause rapid and large changes in the levels of various desaturated fatty acids. We isolated two distinct parsley cDNAs sharing high sequence similarity with microsomal [omega]-6 fatty acid desaturases (FADs). One of them was functionally identified as a [delta]12 FAD by expression in the yeast Saccharomyces cerevisiae. Two dienoic fatty acids, hexadecadienoic and linoleic, which were not detectable in control cells, together constituted up to 12% of the total fatty acids in the transformed yeast cells. [delta]12 FAD mRNA accumulated rapidly and transiently in elicitor-treated parsley cells, protoplasts, and leaves. These and previous results indicate that fatty acid desaturation is an important early component of the complex defense response of parsley to attempted fungal infection.
Purification and Characterization of a Galactose-Rich Basic Glycoprotein in Tobacco1
Authors: Takeichi Tetsuo , Takeuchi Junko , Kaneko Takako , Kawasaki Shinji 
Published: July 2002

Abstract
We found a galactose-rich basic glycoprotein (GBGP) in the cell walls of cultured tobacco (Nicotiana tabacum) cells. GBGP and extensin were isolated as the major components of basic, salt-extracted cell wall glycoproteins. GBGP and extensin were separated by gel filtration in 6 m guanidine hydrochloride as 49- and 90-kD peaks, respectively, and further purified with reverse-phase chromatography. The protein moiety of GBGP constitutes about one-half of the molecule (w/w) and contains lysine (16%), proline (12%), hydroxyproline (10%), tyrosine (4%), alanine (7%), leucine (6%), and cystine (1.4%). Galactose accounted for 72% of the sugar moiety, arabinose content was low (17%), and a significant amount of mannose (7%) was found. No immunological cross-reaction was detected between GBGP and extensin. The antibody against native GBGP with sugar chains reacted with other glycoproteins on the gel blots, whereas the antibodies against deglycosylated GBGP and native extensin were highly specific. Immunolocalization analysis in tobacco stems showed that GBGP is specific to parenchyma tissue and that extensin localizes in the epidermis. This tissue-specific and exclusive distribution suggests important functions of these basic glycoproteins.
Overexpression of Nitrate Reductase in Tobacco Delays Drought-Induced Decreases in Nitrate Reductase Activity and mRNA1
Authors: Ferrario-Méry Sylvie , Valadier Marie-Hélène , Foyer Christine H. 
Published: July 2002

Abstract
Transformed (cauliflower mosaic virus 35S promoter [35S]) tobacco (Nicotiana plumbaginifoliaL.) plants constitutively expressing nitrate reductase (NR) and untransformed controls were subjected to drought for 5 d. Drought-induced changes in biomass accumulation and photosynthesis were comparable in both lines of plants. After 4 d of water deprivation, a large increase in the ratio of shoot dry weight to fresh weight was observed, together with a decrease in the rate of photosynthetic CO2 assimilation. Foliar sucrose increased in both lines during water stress, but hexoses increased only in leaves from untransformed controls. Foliar NO3−decreased rapidly in both lines and was halved within 2 d of the onset of water deprivation. Total foliar amino acids decreased in leaves of both lines following water deprivation. After 4 d of water deprivation no NR activity could be detected in leaves of untransformed plants, whereas about 50% of the original activity remained in the leaves of the 35S-NR transformants. NR mRNA was much more stable than NR activity. NR mRNA abundance increased in the leaves of the 35S-NR plants and remained constant in controls for the first 3 d of drought. On the 4th d, however, NR mRNA suddenly decreased in both lines. Rehydration at d 3 caused rapid recovery (within 24 h) of 35S-NR transcripts, but no recovery was observed in the controls. The phosphorylation state of the protein was unchanged by long-term drought. There was a strong correlation between maximal extractable NR activity and ambient photosynthesis in both lines. We conclude that drought first causes increased NR protein turnover and then accelerates NR mRNA turnover. Constitutive NR expression temporarily delayed drought-induced losses in NR activity. 35S-NR expression may therefore allow more rapid recovery of N assimilation following short-term water deficit.
A New Class of Arabidopsis Mutants with Reduced Hexadecatrienoic Acid Fatty Acid Levels1
Authors: Miquel Martine , Cassagne Claude , Browse John 
Published: July 2002

Abstract
Chloroplast glycerolipids in a number of higher-plant species, including Arabidopsis thaliana, are synthesized by two distinct pathways termed the prokaryotic and eukaryotic pathways. The molecules of galactolipids produced by the prokaryotic pathway contain substantial amounts of hexadecatrienoic acid fatty acid. Here we describe a new class of mutants, designatedgly1, with reduced levels of hexadecatrienoic acid. Lipid fatty acid profiles indicated that gly1 mutants exhibited a reduced carbon flux through the prokaryotic pathway that was compensated for by an increased carbon flux through the eukaryotic pathway. Genetic and biochemical approaches revealed that thegly1 phenotype could not be explained by a deficiency in the enzymes of the prokaryotic pathway. The flux of fatty acids into the prokaryotic pathway is sensitive to changes in glycerol-3-phosphate (G3P) availability, and the chloroplast G3P pool can be increased by exogenous application of glycerol to leaves. Exogenous glycerol treatment of gly1 plants allowed chemical complementation of the mutant phenotype. These results are consistent with a mutant lesion affecting the G3P supply within the chloroplast. The gly1 mutants may therefore help in determining the pathway for synthesis of chloroplast G3P.
S-Adenosyl-l-Methionine:l-MethionineS-Methyltransferase from Germinating Barley
Authors: João Pimenta Maria , Kaneta Tsuyoshi , Larondelle Yvan , Dohmae Naoshi , Kamiya Yuji 
Published: July 2002

Abstract
S-Adenosyl-l-methionine:l-methionineS-methyltransferase (MMT) catalyzes the synthesis ofS-methyl-l-methionine (SMM) froml-methionine andS-adenosyl-l-methionine. SMM content increases during barley (Hordeum vulgare L.) germination. Elucidating the role of this compound is important from both a fundamental and a technological standpoint, because SMM is the precursor of dimethylsulfide, a biogenic source of atmospheric S and an undesired component in beer. We present a simple purification scheme for the MMT from barley consisting of 10% to 25% polyethylene glycol fractionation, anion-exchange chromatography on diethylaminoethyl-Sepharose, and affinity chromatography on adenosine-agarose. A final activity yield of 23% and a 2765-fold purification factor were obtained. After digestion of the protein with protease, the amino acid sequence of a major peptide was determined and used to produce a synthetic peptide. A polyclonal antibody was raised against this synthetic peptide conjugated to activated keyhole limpet hemocyanin. The antibody recognized the 115-kD denatured MMT protein and native MMT. During barley germination, both the specific activity and the amount of MMT protein increased. MMT-specific activity was found to be higher in the root and shoot than in the endosperm. MMT could be localized by an immunohistochemical approach in the shoot, scutellum, and aleurone cells but not in the root or endosperm (including aleurone).
A Nitrilase-Like Protein Interacts with GCC Box DNA-Binding Proteins Involved in Ethylene and Defense Responses
Authors: Xu Ping , Narasimhan Meena L. , Samson Teresa , Coca Maria A. , Huh Gyung-Hye , Zhou Jianmin , Martin Gregory B. , Hasegawa Paul M. , Bressan Ray A. 
Published: July 2002

Abstract
Ethylene-responsive element-binding proteins (EREBPs) of tobacco (Nicotiana tabacum L.) bind to the GCC box of many pathogenesis-related (PR) gene promoters, including osmotin (PR-5). The two GCC boxes on the osmotin promoter are known to be required, but not sufficient, for maximal ethylene responsiveness. EREBPs participate in the signal transduction pathway leading from exogenous ethylene application and pathogen infection to PR gene induction. In this study EREBP3 was used as bait in a yeast two-hybrid interaction trap with a tobacco cDNA library as prey to isolate signal transduction pathway intermediates that interact with EREBPs. One of the strongest interactors was found to encode a nitrilase-like protein (NLP). Nitrilase is an enzyme involved in auxin biosynthesis. NLP interacted with other EREBP family members, namely tobacco EREBP2 and tomato (Lycopersicon esculentum L.) Pti4/5/6. The EREBP2-EREBP3 interaction with NLP required part of the DNA-binding domain. The specificity of interaction was further confirmed by protein-binding studies in solution. We propose that the EREBP-NLP interaction serves to regulate PR gene expression by sequestration of EREBPs in the cytoplasm.
Expression Analysis of a Ripening-Specific, Auxin-Repressed Endo-1,4-β-Glucanase Gene in Strawberry
Authors: Harpster Mark H. , Brummell David A. , Dunsmuir Pamela 
Published: July 2002

AbstractA cDNA (Cel1) encoding an endo-1,4-β-glucanase (EGase) was isolated from ripe fruit of strawberry (Fragaria × ananassa). The deduced protein of 496 amino acids contains a presumptive signal sequence, a common feature of cell wall-localized EGases, and one potential N-glycosylation site. Southern- blot analysis of genomic DNA from F. × ananassa, an octoploid species, and that from the diploid species Fragaria vesca indicated that the Cel1 gene is a member of a divergent multigene family. In fruit, Cel1 mRNA was first detected at the white stage of development, and at the onset of ripening, coincident with anthocyanin accumulation, Cel1mRNA abundance increased dramatically and remained high throughout ripening and subsequent fruit deterioration. In all other tissues examined, Cel1 expression was invariably absent. Antibodies raised to Cel1 protein detected a protein of 62 kD only in ripening fruit. Upon deachenation of young white fruit to remove the source of endogenous auxins, ripening, as visualized by anthocyanin accumulation, and Cel1 mRNA accumulation were both accelerated. Conversely, auxin treatment of white fruit repressed accumulation of both Cel1 mRNA and ripening. These results indicate that strawberry Cel1 is a ripening-specific and auxin-repressed EGase, which is regulated during ripening by a decline in auxin levels originating from the achenes.
Change in Apoplastic Aluminum during the Initial Growth Response to Aluminum by Roots of a Tolerant Maize Variety1
Authors: Vázquez María Dolores , Poschenrieder Charlotte , Corrales Isabel , Barceló Juan 
Published: July 2002

Abstract
Root elongation, hematoxylin staining, and changes in the ultrastructure of root-tip cells of an Al-tolerant maize variety (Zea mays L. C 525 M) exposed to nutrient solutions with 20 μm Al (2.1 μm Al3+ activity) for 0, 4, and 24 h were investigated in relation to the subcellular distribution of Al using scanning transmission electron microscopy and energy-dispersive x-ray microanalysis on samples fixed by different methods. Inhibition of root-elongation rates, hematoxylin staining, cell wall thickening, and disturbance of the distribution of pyroantimoniate-stainable cations, mainly Ca, was observed only after 4 and not after 24 h of exposure to Al. The occurrence of these transient, toxic Al effects on root elongation and in cell walls was accompanied by the presence of solid Al-P deposits in the walls. Whereas no Al was detectable in cell walls after 24 h, an increase of vacuolar Al was observed after 4 h of exposure. After 24 h, a higher amount of electron-dense deposits containing Al and P or Si was observed in the vacuoles. These results indicate that in this tropical maize variety, tolerance mechanisms that cause a change in apoplastic Al must be active. Our data support the hypothesis that in Al-tolerant plants, Al can rapidly cross the plasma membrane; these data clearly contradict the former conclusions that Al mainly accumulates in the apoplast and enters the symplast only after severe cell damage has occurred.
NADH-Glutamate Synthase in Alfalfa Root Nodules. Immunocytochemical Localization1
Authors: Trepp Gian B. , Plank David W. , Stephen Gantt J. , Vance Carroll P. 
Published: July 2002

Abstract
In root nodules of alfalfa (Medicago sativa L.), N2 is reduced to NH4+ in the bacteroid by the nitrogenase enzyme and then released into the plant cytosol. The NH4+ is then assimilated by the combined action of glutamine synthetase (EC 6.3.1.2) and NADH-dependent Glu synthase (NADH-GOGAT; EC 1.4.1.14) into glutamine and Glu. The alfalfa nodule NADH-GOGAT protein has a 101-amino acid presequence, but the subcellular location of the protein is unknown. Using immunocytochemical localization, we determined first that the NADH-GOGAT protein is found throughout the infected cell region of both 19- and 33-d-old nodules. Second, in alfalfa root nodules NADH-GOGAT is localized predominantly to the amyloplast of infected cells. This finding, together with earlier localization and fractionation studies, indicates that in alfalfa the infected cells are the main location for the initial assimilation of fixed N2.
Chloroplast-Targeted ERD1 Protein Declines but Its mRNA Increases during Senescence in Arabidopsis1
Authors: Weaver L. Michael , Froehlich John E. , Amasino Richard M. 
Published: July 2002

AbstractArabidopsis ERD1 is a ClpC-like protein that sequence analysis suggests may interact with the chloroplast-localized ClpP protease to facilitate proteolysis. The mRNA encoded by the ERD1 gene has previously been shown to accumulate in response to senescence and to a variety of stresses and hormones. Here we show that the ERD1 protein, in contrast to theERD1 mRNA, strongly declines in abundance with age, becoming undetectable in fully expanded leaves. Sequence analysis also suggests that ERD1 is chloroplast targeted, and we show in an in vitro system that the native protein is properly imported, processed, and present within the soluble fraction of the chloroplast, presumably the stroma. We show that ClpP protein, which is also present in the stroma, declines with age in parallel with ERD1. These results are consistent with the interaction of ERD1 and ClpP, but they suggest that it is unlikely that either plays a major role during senescence. Certain other chloroplast proteins decline with age coordinately with ERD1 and ClpP, suggesting that these declines are markers of an early age-mediated change that occurs within the chloroplast.
Changes in Phosphoinositide Metabolism with Days in Culture Affect Signal Transduction Pathways inGaldieria sulphuraria1
Authors: Heilmann Ingo , Perera Imara Y. , Gross Wolfgang , Boss Wendy F. 
Published: July 2002

Abstract
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−1fresh 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−1mg−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 IP3signaling 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.
Processing, Targeting, and Antifungal Activity of Stinging Nettle Agglutinin in Transgenic Tobacco
Authors: Does Mirjam P. , Houterman Petra M. , Dekker Henk L. , Cornelissen Ben J.C. 
Published: July 2002

Abstract
The gene encoding the precursor to stinging nettle (Urtica dioica L.) isolectin I was introduced into tobacco (Nicotiana tabacum). In transgenic plants this precursor was processed to mature-sized lectin. The mature isolectin is deposited intracellularly, most likely in the vacuoles. A gene construct lacking the C-terminal 25 amino acids was also introduced in tobacco to study the role of the C terminus in subcellular trafficking. In tobacco plants that expressed this construct, the mutant precursor was correctly processed and the mature isolectin was targeted to the intercellular space. These results indicate the presence of a C-terminal signal for intracellular retention of stinging nettle lectin and most likely for sorting of the lectin to the vacuoles. In addition, correct processing of this lectin did not depend on vacuolar deposition. Isolectin I purified from tobacco displayed identical biological activities as isolectin I isolated from stinging nettle. In vitro antifungal assays on germinated spores of the fungiBotrytis cinerea, Trichoderma viride, andColletotrichum lindemuthianum revealed that growth inhibition by stinging nettle isolectin I occurs at a specific phase of fungal growth and is temporal, suggesting that the fungi had an adaptation mechanism.