bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improving precipitation estimates from weather radar using quality control and correction techniques
Authors: Harrison D L , Driscoll S J , Kitchen M 
Published: July 2002

AbstractErrors and uncertainty in radar estimates of precipitation result both from errors in the basic measurement of reflectivity and from attempts to relate this to the precipitation falling at the ground. If radar data are to be used to their full potential, it is essential that effective measures are taken to mitigate these problems. The automatic processing of radar data that forms part of the UK Met. Office's Nimrod system addresses a number of specific sources of error. These include the identification and removal of spurious echoes resulting from anomalous propagation of the radar beam, errors resulting from variations in the vertical profile of reflectivity and radar sensitivity errors. Routine verification of the surface precipitation estimates has been undertaken, largely through comparison with rain gauge observations, over a range of timescales, which has allowed the benefits of the quality control and correction processes to be quantified. Although the improvement derived varies according to the dominant synoptic situation, an average reduction in the root‐mean‐square difference between gauge and radar data of 30% can be achieved. Copyright © 2000 Royal Meteorological Society
Human–Ovine Comparative Sequencing of a 250-kb Imprinted Domain Encompassing the Callipyge (clpg) Locus and Identification of Six Imprinted Transcripts: DLK1, DAT, GTL2, PEG11, antiPEG11, and MEG8
Authors: Charlier Carole , Segers Karin , Wagenaar Danny , Karim Latifa , Berghmans Stéphane , Jaillon Olivier , Shay Tracy , Weissenbach Jean , Cockett Noelle , Gyapay Gabor , Georges Michel 
Published: July 2002

Two ovine BAC clones and a connecting long-range PCR product, jointly spanning ∼250 kb and representing most of theMULGE5-OY3 marker interval known to contain the clpglocus, were completely sequenced. The resulting genomic sequence was aligned with its human ortholog and extensively annotated. Six transcripts, four of which were novel, were predicted to originate from within the analyzed region and their existence confirmed experimentally: DLK1, DAT, GTL2, PEG11, antiPEG11, and MEG8. RT-PCR experiments performed on a range of tissues sampled from an 8-wk-old animal demonstrated the preferential expression of all six transcripts in skeletal muscle, which suggests that they are under control of common regulatory elements. The six transcripts were also shown to be subject to parental imprinting: DLK1, DAT, andPEG11 were shown to be paternally expressed and GTL2,antiPEG11, and MEG8 to be maternally expressed.[The sequence data described in this paper have been submitted to the GenBank data library under accession no. AF354168.]
Rate of Dehydration and Cumulative Desiccation Stress Interacted to Modulate Desiccation Tolerance of Recalcitrant Cocoa and Ginkgo Embryonic Tissues
Authors: Liang Yongheng , Sun Wendell Q. 
Published: July 2002

Abstract
Rate of dehydration greatly affects desiccation tolerance of recalcitrant seeds. This effect is presumably related to two different stress vectors: direct mechanical or physical stress because of the loss of water and physicochemical damage of tissues as a result of metabolic alterations during drying. The present study proposed a new theoretic approach to represent these two types of stresses and investigated how seed tissues responded differently to two stress vectors, using the models of isolated cocoa (Theobroma cacao) and ginkgo (Ginkgo biloba) embryonic tissues dehydrated under various drying conditions. This approach used the differential change in axis water potential (ΔΨ/Δt) to quantify rate of dehydration and the intensity of direct physical stress experienced by embryonic tissues during desiccation. Physicochemical effect of drying was expressed by cumulative desiccation stress [∫ot f(ψ,t)], a function of both the rate and time of dehydration. Rapid dehydration increased the sensitivity of embryonic tissues to desiccation as indicated by high critical water contents, below which desiccation damage occurred. Cumulative desiccation stress increased sharply under slow drying conditions, which was also detrimental to embryonic tissues. This quantitative analysis of the stress-time-response relationship helps to understand the physiological basis for the existence of an optimal dehydration rate, with which maximum desiccation tolerance could be achieved. The established numerical analysis model will prove valuable for the design of experiments that aim to elucidate biochemical and physiological mechanisms of desiccation tolerance.
The Priming of Amylose Synthesis in Arabidopsis Leaves
Authors: Zeeman Samuel C. , Smith Steven M. , Smith Alison M. 
Published: July 2002

Abstract
We investigated the mechanism of amylose synthesis in Arabidopsis leaves using 14C-labeling techniques. First, we tested the hypothesis that short malto-oligosaccharides (MOS) may act as primers for granule-bound starch synthase I. We found increased amylose synthesis in isolated starch granules supplied with ADP[14C]glucose (ADP[14C]Glc) and MOS compared with granules supplied with ADP[14C]Glc but no MOS. Furthermore, using a MOS-accumulating mutant (dpe1), we found that more amylose was synthesized than in the wild type, correlating with the amount of MOS in vivo. When wild-type and mutant plants were tested in conditions where both lines had similar MOS contents, no difference in amylose synthesis was observed. We also tested the hypothesis that branches of amylopectin might serve as the primers for granule-bound starch synthase I. In this model, elongated branches of amylopectin are subsequently cleaved to form amylose. We conducted pulse-chase experiments, supplying a pulse of ADP[14C]Glc to isolated starch granules or14CO2 to intact plants, followed by a chase period in unlabeled substrate. We detected no transfer of label from the amylopectin fraction to the amylose fraction of starch either in isolated starch granules or in intact leaves, despite varying the time course of the experiments and using a mutant line (sex4) in which high-amylose starch is synthesized. We therefore find no evidence for amylopectin-primed amylose synthesis in Arabidopsis. We propose that MOS are the primers for amylose synthesis in Arabidopsis leaves.
Iron and Copper Nutrition-Dependent Changes in Protein Expression in a Tomato Wild Type and the Nicotianamine-Free Mutant chloronerva
Authors: Herbik A. , Giritch A. , Horstmann C. , Becker R. , Balzer H. J. , Baumlein H. , Stephan U. W. 
Published: July 2002

Abstract
The nicotianamine-deficient mutant chloronerva resembles phenotypically an Fe-deficient plant despite the high accumulation of Fe in the leaves, whereas it suffers from Cu deficiency in the shoot. Two-dimensional electrophoretic separation of proteins from root tips and leaves of wild-type Lycopersicon esculentum Mill. cv Bonner Beste and the mutant grown with and without Fe showed a number of consistent differences. In root tips of the Fe-deficient wild type and the Fe-sufficient as well as the Fe-deficient mutant, the expression of glyceraldehyde-3-phosphate dehydrogenase, formate dehydrogenase, and ascorbate peroxidase was increased. In leaves of the Fe-sufficient and -deficient mutant, Cu-containing chloroplastic and cytosolic superoxide dismutase (Cu-Zn) and plastocyanin (Cu) were nearly absent. This low plastocyanin content could be restored by supplying Cu via the xylem, but the superoxide dismutase levels could not be increased by this treatment. The differences in the protein patterns between wild type and mutant indicate that the apparent Fe deficiency of mutant plants led to an increase in enzymes involved in anaerobic metabolism as well as enzymes involved in stress defense. The biosynthesis of plastocyanin was diminished in mutant leaves, but it was differentially induced by increased Cu content.
Cloning of a cDNA Encoding Cytosolic Acetoacetyl-Coenzyme A Thiolase from Radish by Functional Expression in Saccharomyces cerevisiae
Authors: Vollack K. U. , Bach T. J. 
Published: July 2002

Abstract
A cDNA coding for radish (Raphanus sativus L.) acetoacetyl-coenzyme A thiolase (AACT) was cloned by complementation of the erg10 mutation affecting AACT in yeast (Saccharomyces cerevisiae). The longest reading frame encodes a protein of 406 amino acids with a predicted relative molecular weight of 42,032, with significant similarities to eukaryotic and prokaryotic thiolases. There is no evidence for the presence of a leader peptide characteristic, e.g. of glyoxysomal thiolase. Yeast transformants expressing the radish AACT gene placed under the control of the GAL1 promoter exhibited a 10-fold higher enzyme activity than a wild-type yeast strain after induction by galactose. This enzyme activity is exclusively localized in the soluble fraction but not in membranes. These data indicate that we have cloned a gene encoding cytoplasmic (biosynthetic) AACT. Genomic DNA gel blot analysis suggests the presence of a single AACT gene, which is expressed in all parts of the seedling. Expression in cotyledons appears to be light-stimulated. We present preliminary evidence that a smaller transcript represents an antisense species being read from the same gene.
Arabidopsis thaliana sku Mutant Seedlings Show Exaggerated Surface-Dependent Alteration in Root Growth Vector
Authors: Rutherford R. , Masson P. H. 
Published: July 2002

Abstract
Roots of wild-type Arabidopsis thaliana seedlings in the Wassilewskija (WS) and Landsberg erecta (Ler) ecotypes often grow aslant on vertical agar surfaces. Slanted root growth always occurs to the right of the gravity vector when the root is viewed through the agar surface, and is not observed in the Columbia ecotype. Right-slanted root growth is surface-dependent and does not result directly from directional environmental stimuli or gradients in the plane of skewing. We have isolated two partially dominant mutations in WS (sku1 and sku2) that show an exaggerated right-slanting root-growth phenotype on agar surfaces. The right-slanting root-growth phenotype of wild-type and mutant roots is not the result of diagravitropism or of an alteration in root gravitropism. It is accompanied by a left-handed rotation of the root about its axis within the elongation zone, the rate of which positively correlates with the degree of right-slanted curvature. Our data suggest that the right-slanting root growth phenotype results from an endogenous structural asymmetry that expresses itself by a directional root-tip rotation.
Antagonistic but Complementary Actions of Phytochromes A and B Allow Optimum Seedling De-Etiolation
Authors: Smith H. , Xu Y. , Quail P. H. 
Published: July 2002

Abstract
Using dichromatic radiation, we show that the actions of phytochromes A and B (phyA and phyB) in Arabidopsis thaliana are antagonistic in mediating red and far-red radiation effects on seedling de-etiolation and yet act in a complementary manner to regulate de-etiolation, irrespective of spectral composition. At low phytochrome photoequilibria inhibition of hypocotyl extension was strong, because of the action of a far-red high-irradiance response mediated by phyA. At high phytochrome photoequilibria inhibition of hypocotyl extension was also strong, because of the action of phyB. At intermediate photoequilibria hypocotyl inhibition was less strong. In their natural environment, this dual action will strongly retard hypocotyl growth and promote cotyledon opening and expansion both in open daylight and under dense vegetation. Overlapping action by phyA and phyB will substantially promote de-etiolation in sparse vegetation. The antagonistic and complementary actions of phyA and phyB, therefore, allow the optimum regulation of seedling growth after emergence from the soil.
Purification and Characterization of a Novel Class III Peroxidase Isoenzyme from Tea Leaves
Authors: Kvaratskhelia M. , Winkel C. , Thorneley RNF. 
Published: July 2002

Abstract
A novel, basic (isoelectric point &gt; 10), heme peroxidase isoenzyme (TP; relative molecular weight = 34,660 [plus or minus] 10, mean [plus or minus] SE) that can account for a significant part of the ascorbate peroxidase activity in tea (Camellia sinensis) leaves has been purified to homogeneity. The ultraviolet/visible absorption spectrum is typical of heme-containing plant peroxidases, with a Soret peak at 406 nm ([epsilon] = 115 mM-1 cm-1) and an A406/A280 value of 3.4. The enzyme has a high specific activity for ascorbate oxidation (151 [mu]mol min-1 mg-1), with a pH optimum in the range of 4.5 to 5.0. Substrate-specificity studies have revealed significant differences between TP and other class III peroxidases, as well as similarities with class I ascorbate peroxidases. TP, like ascorbate peroxidase, exhibits a preference for ascorbate over guaiacol, whereas other class III isoenzymes are characterized by 2-orders-of-magnitude higher activity for guaiacol than for ascorbate. TP also forms an unstable porphyrin [pi] cation radical-type compound I, which is converted to compound II within approximately 2 min in the absence of added reductant. Amino acid sequence data show TP to be the first example, to our knowledge, of a class III peroxidase with a high specificity for ascorbate as an electron donor.
[gamma]-Aminobutyric Acid Stimulates Ethylene Biosynthesis in Sunflower
Authors: Kathiresan A. , Tung P. , Chinnappa C. C. , Reid D. M. 
Published: July 2002

Abstract
[gamma]-Aminobutyric acid (GABA), a nonprotein amino acid, is often accumulated in plants following environmental stimuli that can also cause ethylene production. We have investigated the relationship between GABA and ethylene production in excised sunflower (Helianthus annuus L.) tissues. Exogenous GABA causes up to a 14-fold increase in the ethylene production rate after about 12 h. Cotyledons fed with [14C]GABA did not release substantial amounts of radioactive ethylene despite its chemical similarity to 1-aminocyclopropane-1-carboxylic acid (ACC), indicating that GABA is not likely to be an alternative precursor for ethylene. GABA causes increases in ACC synthase mRNA accumulation, ACC levels, ACC oxidase mRNA levels, and in vitro ACC oxidase activity. In the presence of aminoethoxyvinylglycine or α--aminoisobutyric acid, GABA did not stimulate ethylene production. We therefore conclude that GABA stimulates ethylene biosynthesis mainly by promoting ACC synthase transcript abundance. Possible roles of GABA as a signal transducer are suggested.
Photosystem I Is an Early Target of Photoinhibition in Barley Illuminated at Chilling Temperatures1
Authors: Erling Tjus Staffan , Lindberg Møller Birger , Vibe Scheller Henrik 
Published: July 2002

Abstract
Light-induced damage to photosystem I (PSI) was studied during low-light illumination of barley (Hordeum vulgare L.) at chilling temperatures. A 4-h illumination period induced a significant inactivation of PSI electron transport activity. Flash-induced P700 absorption decay measurements revealed progressive damage to (a) the iron-sulfur clusters FA and FB, (b) the iron-sulfur clusters FA, FB, and FX, and (c) the phylloquinone A1 and the chlorophyll A0 or P700 of the PSI electron acceptor chain. Light-induced PSI damage was also evidenced by partial degradation of the PSI-A and PSI-B proteins and was correlated with the appearance of smaller proteins. Aggravated photodamage was observed upon illumination of barley leaves infiltrated with KCN, which inhibits Cu,Zn-superoxide dismutase and ascorbate peroxidase. This indicates that the photodamage of PSI in barley observed during low-light illumination at chilling temperatures arises because the defense against active oxygen species by active oxygen-scavenging enzymes is insufficient at these specific conditions. The data obtained demonstrate that photoinhibition of PSI at chilling temperatures is an important phenomenon in a cold-tolerant plant species.
Polypeptides of the Maize Amyloplast Stroma1
Authors: Yu Ying , He Mu Helen , Mu-Forster Chen , Wasserman Bruce P. 
Published: July 2002

AbstractIn the developing endosperm of monocotyledonous plants, starch granules are synthesized and deposited within the amyloplast. A soluble stromal fraction was isolated from amyloplasts of immature maize (Zea mays L.) endosperm and analyzed for enzyme activities and polypeptide content. Specific activities of starch synthase and starch-branching enzyme (SBE), but not the cytosolic marker alcohol dehydrogenase, were strongly enhanced in soluble amyloplast stromal fractions relative to soluble extracts obtained from homogenized kernels or endosperms. Immunoblot analysis demonstrated that starch synthase I, SBEIIb, and sugary1, the putative starch-debranching enzyme, were each highly enriched in the amyloplast stroma, providing direct evidence for the localization of starch-biosynthetic enzymes within this compartment. Analysis of maize mutants shows the deficiency of the 85-kD SBEIIb polypeptide in the stroma of amylose extender cultivars and that the dull mutant lacks a &gt;220-kD stromal polypeptide. The stromal fraction is distinguished by differential enrichment of a characteristic group of previously undocumented polypeptides. N-terminal sequence analysis revealed that an abundant 81-kD stromal polypeptide is a member of the Hsp70 family of stress-related proteins. Moreover, the 81-kD stromal polypeptide is strongly recognized by antibodies specific for an Hsp70 of the chloroplast stroma. These findings are discussed in light of implications for the correct folding and assembly of soluble, partially soluble, and granule-bound starch-biosynthetic enzymes during import into the amyloplast.
Aluminum-Resistant Arabidopsis Mutants That Exhibit Altered Patterns of Aluminum Accumulation and Organic Acid Release from Roots1
Authors: Larsen Paul B. , Degenhardt Jörg , Tai Chin-Yin , Stenzler Laura M. , Howell Stephen H. , Kochian Leon V. 
Published: July 2002

Abstract
Al-resistant (alr) mutants of Arabidopsis thalianawere isolated and characterized to gain a better understanding of the genetic and physiological mechanisms of Al resistance.alr mutants were identified on the basis of enhanced root growth in the presence of levels of Al that strongly inhibited root growth in wild-type seedlings. Genetic analysis of thealr mutants showed that Al resistance was semidominant, and chromosome mapping of the mutants with microsatellite and random amplified polymorphic DNA markers indicated that the mutants mapped to two sites in the Arabidopsis genome: one locus on chromosome 1 (alr-108, alr-128,alr-131, and alr-139) and another on chromosome 4 (alr-104). Al accumulation in roots of mutant seedlings was studied by staining with the fluorescent Al-indicator dye morin and quantified via inductively coupled argon plasma mass spectrometry. It was found that the alrmutants accumulated lower levels of Al in the root tips compared with wild type. The possibility that the mutants released Al-chelating organic acids was examined. The mutants that mapped together on chromosome 1 released greater amounts of citrate or malate (as well as pyruvate) compared with wild type, suggesting that Al exclusion from roots of these alr mutants results from enhanced organic acid exudation. Roots of alr-104, on the other hand, did not exhibit increased release of malate or citrate, but did alkalinize the rhizosphere to a greater extent than wild-type roots. A detailed examination of Al resistance in this mutant is described in an accompanying paper (J. Degenhardt, P.B. Larsen, S.H. Howell, L.V. Kochian [1998] Plant Physiol 117: 19–27).
Metabolism of Uridine 5′-Diphosphate-Glucose in Golgi Vesicles from Pea Stems1
Authors: Neckelmann Guy , Orellana Ariel 
Published: July 2002

Abstract
Uridine 5′-diphosphate-glucose (UDP-Glc) is transported into the lumen of the Golgi cisternae, where is used for polysaccharide biosynthesis. When Golgi vesicles were incubated with UDP-[3H]Glc, [3H]Glc was rapidly transferred to endogenous acceptors and UDP-Glc was undetectable in Golgi vesicles. This result indicated that a uridine-containing nucleotide was rapidly formed in the Golgi vesicles. Since little is known about the fate of the nucleotide derived from UDP-Glc, we analyzed the metabolism of the nucleotide moiety of UDP-Glc by incubating Golgi vesicles with [α-32P]UDP-Glc, [β-32P]UDP-Glc, and [3H]UDP-Glc and identifying the resulting products. After incubation of Golgi vesicles with these radiolabeled substrates we could detect only uridine 5′-monophosphate (UMP) and inorganic phosphate (Pi). UDP could not be detected, suggesting a rapid hydrolysis of UDP by the Golgi UDPase. The by-products of UDP hydrolysis, UMP and Pi, did not accumulate in the lumen, indicating that they were able to exit the Golgi lumen. The exit of UMP was stimulated by UDP-Glc, suggesting the presence of a putative UDP-Glc/UMP antiporter in the Golgi membrane. However, the exit of Pi was not stimulated by UDP-Glc, suggesting that the exit of Pi occurs via an independent membrane transporter.
Chemotropic and Contact Responses of Phytophthora sojae Hyphae to Soybean Isoflavonoids and Artificial Substrates1
Authors: Morris Paul F. , Bone Elizabeth , Tyler Brett M. 
Published: July 2002

Abstract
We have investigated the role of the isoflavones daidzein and genistein on the chemotropic behavior of germinating cysts of Phytophthora sojae. Hyphal germlings were shown to respond chemotropically to daidzein and genistein, suggesting that hyphal tips from zoospores that have encysted adjacent to the root may use specific host isoflavones to locate their host. Observations of the contact response of hyphal germlings were made on several different substrates in the presence and absence of isoflavones. Hyphal tips of germlings detected and penetrated pores in membranes and produced multiple appressoria on smooth, impenetrable surfaces. Hyphae that successfully penetrated the synthetic membrane were observed to grow away from the membrane surface. The presence of isoflavones in the medium surrounding the hyphal germlings did not appear to alter any of those habits. Daidzein and genistein did not inhibit germination or initial hyphal growth at concentrations up to 20 μm.
Expressed Sequence Tags from a Root-Hair-Enriched Medicago truncatula cDNA Library1
Authors: Covitz Peter A. , Smith Lucinda S. , Long Sharon R. 
Published: July 2002

Abstract
The root hair is a specialized cell type involved in water and nutrient uptake in plants. In legumes the root hair is also the primary site of recognition and infection by symbiotic nitrogen-fixingRhizobium bacteria. We have studied the root hairs ofMedicago truncatula, which is emerging as an increasingly important model legume for studies of symbiotic nodulation. However, only 27 genes from M. truncatulawere represented in GenBank/EMBL as of October, 1997. We report here the construction of a root-hair-enriched cDNA library and single-pass sequencing of randomly selected clones. Expressed sequence tags (899 total, 603 of which have homology to known genes) were generated and made available on the Internet. We believe that the database and the associated DNA materials will provide a useful resource to the community of scientists studying the biology of roots, root tips, root hairs, and nodulation.