bluuebunny/crossref_metadata_2025_split huggingface dataset:
Contrasts in conservation attitudes and agricultural practices between farmers operating in wetlands and a plain in Macedonia, Greece
Authors: PYROVETSI MYRTO , DAOUTOPOULOS GEORGE 
Published: July 2002

Conservation projects around the world have been impeded by conflicting land uses. In Greece, although agriculture is considered to have significant impacts on wetlands and adversely to have affected conservation, the attitudes of Greek farmers to wetlands and conservation have not been assessed. Data on demographic variables of farm operators, characteristics of the farming operation, irrigation practices, attitudes towards environment and the wetland resources, knowledge on the impact of agriculture on the local environment and opinions on the Common Agricultural Policy reform, were collected through a survey using personal interviews from a random sample of 196 farmers operating in two wetlands, Lakes Mikri Prespa and Kerkini (Ramsar sites), and 141 farmers operating in a plain, in Macedonia, northern Greece.Analysis of the data revealed that farmers practise crop and stock agriculture more intensively in wetlands than in the plain, and exploit wetland resources excessively. Hunting, fishing and wood harvesting are practised, and lake water is used intensively for irrigation by both groups of farmers, with no care for loss of the resources. Alternative methods of irrigation for improving efficiency of water use or alleviating hydrological pressures on the wetlands are not considered. Sustainability of agriculture is at risk as present practices result in impoverished soils, salinization of the fields and waste of water resources. Wetland farmers seemed to have a more negative attitude toward the wetland resources and seemed to be more ignorant of conservation issues or the impact of their practices on the environment than plain farmers. Moreover, their awareness and willingness to adopt an environmentally-friendly type of farming was very low.
The fountain amacrine cells of the rabbit retina
Authors: WRIGHT LAYNE L. , VANEY DAVID I. 
Published: July 2002

(article appeared in Visual Neuroscience (1999),
16, 1145–1156.)Due to an unfortunate misunderstanding, Figure 3 that
appeared on p. 1149 of Visual Neuroscience 16:6
was not sized to the full two-column measure. A corrected
version of the article, with Figure 3 reshot to full size,
is reproduced on pp. 1145R–1156R, which follows.
Cambridge University Press regrets any inconvenience that
this inadvertent error may have caused.
Use of METEOSAT water‐vapour images for the diagnosis of a vigorous stratospheric intrusion over the central Mediterranean
Authors: Lagouvardos K , Kotroni V 
Published: July 2002

AbstractThe diagnosis of a vigorous dry intrusion over the central Mediterranean is performed using water‐vapour images from METEOSAT. This dry intrusion was located on the rear side of a cold front (propagating from Italy to Greece) and played an important role in the onset of thunderstorms over the western Greek coasts. A combination of satellite imagery and potential vorticity analyses showed that the dry air originated in the lower‐stratospheric and higher‐tropospheric layers. The interaction of the dry air with the moist air masses within the warm conveyor belt ahead of the cold front (overrun of warm air by low equivalent potential temperature air) produced a potentially unstable region over the area of reported thunderstorms. Copyright © 2000 Royal Meteorological Society
The Verbmobil prototype system – a software
engineering perspective
Authors: BUB THOMAS , SCHWINN JOHANNES 
Published: July 2002

Verbmobil represents a new generation of speech-to-speech translation systems in which
spontaneously spoken language, speaker independence and adaptability as well as the combination
of deep and shallow approaches to the analysis and transfer problems are the main features.
The project brought together researchers from the fields of signal processing, computational
linguistics and artificial intelligence. Verbmobil goes beyond the state-of-the-art in each of
these areas, but its main achievement is the seamless integration of them. The first project
phase (1993–1996) has been followed up by the second project phase (1997–2000), which
aims at applying the results to further languages and at integrating innovative telecooperation
techniques. Quite apart from the speech and language processing issues, the size and
complexity of the project represent an extreme challenge on the areas of project management
and software engineering:[bull ] 50 researchers from 29 organizations at different sites in different countries are involved
in the software development process,[bull ] to reuse existing software, hardware, knowledge and experience, only a few technical
restrictions could be given to the partners.In this article we describe the Verbmobil prototype system from a software-engineering
perspective. We discuss:[bull ] the modularized functional architecture,[bull ] the flexible and extensible software architecture which reflects that functional architecture,[bull ] the evolutionary process of system integration,[bull ] the communication-based organizational structure of the project,[bull ] the evaluation of the system operational by the end of the first project phase.
Pyruvate,Orthophosphate Dikinase in Leaves and Chloroplasts of C3 Plants Undergoes Light-/Dark-Induced Reversible Phosphorylation
Authors: Chastain Chris J. , Fries Jason P. , Vogel Julie A. , Randklev Christa L. , Vossen Adam P. , Dittmer Sharon K. , Watkins Erin E. , Fiedler Lucas J. , Wacker Sarah A. , Meinhover Katherine C. , Sarath Gautam , Chollet Raymond 
Published: July 2002

Abstract
Pyruvate,orthophosphate (Pi) dikinase (PPDK) is best recognized as a chloroplastic C4 cycle enzyme. As one of the key regulatory foci for controlling flux through this photosynthetic pathway, it is strictly and reversibly regulated by light. This light/dark modulation is mediated by reversible phosphorylation of a conserved threonine residue in the active-site domain by the PPDK regulatory protein (RP), a bifunctional protein kinase/phosphatase. PPDK is also present in C3 plants, although it has no known photosynthetic function. Nevertheless, in this report we show that C3 PPDK in leaves of several angiosperms and in isolated intact spinach (Spinacia oleracea) chloroplasts undergoes light-/dark-induced changes in phosphorylation state in a manner similar to C4 dikinase. In addition, the kinetics of this process closely resemble the reversible C4 process, with light-induced dephosphorylation occurring rapidly (≤15 min) and dark-induced phosphorylation occurring much more slowly (≥30–60 min). In intact spinach chloroplasts, light-induced dephosphorylation of C3 PPDK was shown to be dependent on exogenous Pi and photosystem II activity but independent of electron transfer from photosystem I. These in organello results implicate a role for stromal pools of Pi and adenylates in regulating the reversible phosphorylation of C3-PPDK. Last, we used an in vitro RP assay to directly demonstrate ADP-dependent PPDK phosphorylation in desalted leaf extracts of the C3 plantsVicia faba and rice (Oryza sativa). We conclude that an RP-like activity mediates the light/dark modulation of PPDK phosphorylation state in C3 leaves and chloroplasts and likely represents the ancestral isoform of this unusual and key C4 pathway regulatory “converter” enzyme.
Inhibitors of Protein Kinases and Phosphatases Alter Root Morphology and Disorganize Cortical Microtubules
Authors: Baskin T. I. , Wilson J. E. 
Published: July 2002

Abstract
To investigate molecular mechanisms controlling plant morphogenesis, we examined the morphology of primary roots of Arabidopsis thaliana and the organization of cortical microtubules in response to inhibitors of serine/threonine protein phosphatases and kinases. We found that cantharidin, an inhibitor of types 1 and 2A protein phosphatases, as previously reported for okadaic acid and calyculin A (R.D. Smith, J.E. Wilson, J.C. Walker, T.I. Baskin [1994] Planta 194: 516–524), inhibited elongation and stimulated radial expansion. Of the protein kinase inhibitors tested, chelerythrine, 6-dimethylaminopurine, H-89, K252a, ML-9, and staurosporine all inhibited elongation, but only staurosporine appreciably stimulated radial expansion. To determine the basis for the root swelling, we examined cortical microtubules in semithin sections of material embedded in butyl-methyl-methacrylate. Chelerythrine and 100 nM okadaic acid, which inhibited elongation without causing swelling, did not change the appearance of cortical arrays, but calyculin A, cantharidin, and staurosporine, which caused swelling, disorganized cortical microtubules. The stability of the microtubules in the aberrant arrays was not detectably different from those in control arrays, as judged by similar sensitivity to depolymerization by cold or oryzalin. These results identify protein phosphorylation and dephosphorylation
Gibberellin Deficiency and Response Mutations Suppress the Stem Elongation Phenotype of Phytochrome-Deficient Mutants of Arabidopsis
Authors: Peng J. , Harberd N. P. 
Published: July 2002

Abstract
Plant growth and development are regulated by numerous internal and external factors. Among these, gibberellin (GA) (an endogenous plant growth regulator) and phytochrome (a photoreceptor) often influence the same processes. For example, in plants grown in the light Arabidopsis thaliana hypocotyl elongation is reduced by GA deficiency and increased by phytochrome deficiency. Here we describe experiments in which the phenotypes of Arabidopsis plants doubly homozygous for GA-related and phytochrome-related mutations were examined. The double mutants were studied at various stages in the plant life cycle, including the seed germination, young seedling, adult, and reproductive phases of development. The results of these experiments are complex, but indicate that a fully functional GA system is necessary for full expression of the elongated phenotypes conferred by phytochrome deficiency.
Requirement for the H Phosphoprotein in Photosystem II of Chlamydomonas reinhardtii
Authors: Summer E. J. , Schmid VHR. , Bruns B. U. , Schmidt G. W. 
Published: July 2002

Abstract
To dissect the expression of the psbB gene cluster of the Chlamydomonas reinhardtii chloroplast genome and to assess the role of the photosystem II H-phosphoprotein (PSII-H) in the biogenesis and/or stabilization of PSII, an aadA gene cassette conferring spectinomycin resistance was employed for mutagenesis. Disruption of the gene cluster has no effect on the abundance of transcripts of the upstream psbB/T locus. Likewise, interruption of psbB/T and psbH with a strong transcriptional terminator from the rbcL gene does not influence transcript accumulation. Thus, psbB/T and psbH may be independently transcribed, and the latter gene seems to have its own promoter in C. reinhardtii. In the absence of PSII-H, translation and thylakoid insertion of chloroplast PSII core proteins is unaffected, but PSII proteins do not accumulate. Because the deletion mutant also exhibits PSII deficiency when dark-grown, the effect is unrelated to photoinhibition. Turnover of proteins B and C of PSII and the polypeptides PSII protein A and PSII protein D is faster than in wild-type cells but is much slower than that observed in other PSII-deficient mutants of C. reinhardtii, suggesting a peripheral location of PSII-H in PSII. The role of PSII-H on PSII assembly was examined by sucrose gradient fractionation of pulse-labeled thylakoids; the accumulation of high-molecular-weight forms of PSII is severely impaired in the psbH deletion mutant. Thus, a primary role of PSII-H may be to facilitate PSII assembly/stability through dimerization. PSII-H phosphorylation, which possibly occurs at two sites, may also be germane to its role in regulating PSII structure, stabilization, or activity.
Intracellular Carbonic Anhydrase Is Essential to Photosynthesis in Chlamydomonas reinhardtii at Atmospheric Levels of CO2 (Demonstration via Genomic Complementation of the High-CO2-Requiring Mutant ca-1)
Authors: Funke R. P. , Kovar J. L. , Weeks D. P. 
Published: July 2002

Abstract
Genomic complementation of the high-CO2-requiring mutant ca-1–12-1C of Chlamydomonas reinhardtii was achieved by transformation with DNA pools from an indexed cosmid library of wild-type genomic DNA. Transformation of mutant cells with cosmid DNA from two microtiter plates in the library produced colonies that grew phototrophically at atmospheric CO2 levels. Transformations with cosmid DNA from each of the rows and files of the two plates pinpointed one well in each plate with a cosmid bearing the targeted gene. Sequencing of cosmid subclones revealed a gene encoding a recently identified C. reinhardtii chloroplast carbonic anhydrase (CAH3). Transformations with chimeric constructs combining different portions of the wild-type and mutant genes indicated the presence of a mutation in the 5[prime]-half of the gene. Comparison of mutant and wild-type gene sequences in this region revealed a G-to-A substitution in the mutant gene, which produced a nonsense codon. The data presented demonstrate that the carbonic anhydrase produced from the CAH3 gene is essential to the inorganic carbon-concentrating mechanism in C. reinhardtii and that genomic complementation can be a facile and efficient means for isolating genes associated with defects affecting photosynthesis and other physiological processes in this eukaryotic green alga.
Characterization of New Gibberellin-Responsive Semidwarf Mutants of Arabidopsis
Authors: Sponsel V. M. , Schmidt F. W. , Porter S. G. , Nakayama M. , Kohlstruk S. , Estelle M. 
Published: July 2002

Abstract
Chemical mutagenesis of Arabidopsis thaliana (L.) Heynh. yielded four semidwarf mutants, all of which appeared to be gibberellin (GA)-biosynthesis mutants. All four had atypical response profiles to C20-GAs, suggesting that each had impaired 20-oxidation. One mutant, 11.2, was shown to be allelic to ga5 and has been named ga5–2. It had altered metabolism of [14C]GA15 relative to that in wild-type plants and undetectable levels of C19-GAs in young stems, consistent with the known function of GA5 as a stem-expressed GA 20-oxidase. Two mutants (2.1 and 10.3), which had very short inflorescences and siliques, were allelic to each other but not to the known GA-responding mutants, ga1 to ga5. The locus defined by these two mutations is provisionally named GA6 and is purported to encode an inflorescence- and silique-expressed GA 20-oxidase. A double mutant, ga5–2 ga6–2, had an extreme dwarf phenotype with very short siliques. The fourth mutation, 1.1, gave a phenotype like ga5, but was not allelic to any of the known ga mutations. It has not yet been given a gene symbol pending further studies.
Three Drought-Responsive Members of the Nonspecific Lipid-Transfer Protein Gene Family inLycopersicon pennelliiShow Different Developmental Patterns of Expression1
Authors: Treviño Marcela B. , Connell Mary A. O' 
Published: July 2002

AbstractGenomic clones of two nonspecific lipid-transfer protein genes from a drought-tolerant wild species of tomato (Lycopersicon pennellii Corr.) were isolated using as a probe a drought- and abscisic acid (ABA)-induced cDNA clone (pLE16) from cultivated tomato (Lycopersicon esculentumMill.). Both genes (LpLtp1 and LpLtp2) were sequenced and their corresponding mRNAs were characterized; they are both interrupted by a single intron at identical positions and predict basic proteins of 114 amino acid residues. Genomic Southern data indicated that these genes are members of a small gene family inLycopersicon spp. The 3′-untranslated regions fromLpLtp1 and LpLtp2, as well as a polymerase chain reaction-amplified 3′-untranslated region from pLE16 (cross-hybridizing to a third gene in L. pennellii, namely LpLtp3), were used as gene-specific probes to describe expression in L. pennellii through northern-blot analyses. All LpLtp genes were exclusively expressed in the aerial tissues of the plant and all were drought and ABA inducible. Each gene had a different pattern of expression in fruit, and LpLtp1 and LpLtp2, unlikeLpLtp3, were both primarily developmentally regulated in leaf tissue. Putative ABA-responsive elements were found in the proximal promoter regions of LpLtp1 andLpLtp2.
Regulation of Oleoresinosis in Grand Fir (Abies grandis)1
Authors: Steele Christopher L. , Katoh Sadanobu , Bohlmann Jörg , Croteau Rodney 
Published: July 2002

Abstract
Grand fir (Abies grandis Lindl.) has been developed as a model system for the study of wound-induced oleoresinosis in conifers as a response to insect attack. Oleoresin is a roughly equal mixture of turpentine (85% monoterpenes [C10] and 15% sesquiterpenes [C15]) and rosin (diterpene [C20] resin acids) that acts to seal wounds and is toxic to both invading insects and their pathogenic fungal symbionts. The dynamic regulation of wound-induced oleoresin formation was studied over 29 d at the enzyme level by in vitro assay of the three classes of synthases directly responsible for the formation of monoterpenes, sesquiterpenes, and diterpenes from the corresponding C10, C15, and C20 prenyl diphosphate precursors, and at the gene level by RNA-blot hybridization using terpene synthase class-directed DNA probes. In overall appearance, the shapes of the time-course curves for all classes of synthase activities are similar, suggesting coordinate formation of all of the terpenoid types. However, closer inspection indicates that the monoterpene synthases arise earlier, as shown by an abbreviated time course over 6 to 48 h. RNA-blot analyses indicated that the genes for all three classes of enzymes are transcriptionally activated in response to wounding, with the monoterpene synthases up-regulated first (transcripts detectable 2 h after wounding), in agreement with the results of cell-free assays of monoterpene synthase activity, followed by the coordinately regulated sesquiterpene synthases and diterpene synthases (transcription beginning on d 3–4). The differential timing in the production of oleoresin components of this defense response is consistent with the immediate formation of monoterpenes to act as insect toxins and their later generation at solvent levels for the mobilization of resin acids responsible for wound sealing.
Systemin Potentiates the Oxidative Burst in Cultured Tomato Cells1
Authors: Stennis Michael J. , Chandra Sreeganga , Ryan Clarence A. , Low Philip S. 
Published: July 2002

AbstractPlants that have been wounded by insects or other herbivores may be more susceptible to infection by adventitious microbes. Wound-induced signal molecules, which serve to induce responses in the plant that retard further feeding, might also act to prepare a plant for possible pathogen attack. We have examined the effect of a wound-generated systemic messenger (systemin) on a pathogen-stimulated defense-response marker, the oxidative burst. We observed that neither systemin nor its inactive analog (A-17) was able to directly induce H2O2 biosynthesis in suspension-cultured tomato (Lycopersicon esculentum L.) cells, regardless of the duration of exposure of the cells to the two peptides. Similarly, neither systemin nor A-17 was capable of modifying an oligogalacturonide-elicited oxidative burst, as long as elicitor addition occurred within minutes of treatment with systemin or A-17. In contrast, preexposure of the cell cultures to systemin (but not to A-17) led to a time-dependent enhancement of the oligogalacturonide-elicited oxidative burst. By 12 h of exposure, the H2O2 biosynthetic capacity of systemin-treated cells exceeded that of the control cells by a factor of 16 ± 2. A similar up-regulation by systemin of a mechanically stimulated oxidative burst was also observed. Because the systemin-induced augmentation in oxidant synthesis is quantitatively prevented by coincubation with 2 μm cycloheximide, and because the oxidative burst of oligogalacturonic acid-elicited control cells (no systemin exposure) is unaffected by preincubation with cycloheximide, we conclude that systemin enhancement of the tomato-cell oxidative burst requires protein synthesis.
The Site of Oxygen Limitation in Soybean Nodules1
Authors: Kuzma Monika M. , Winter Heike , Storer Paul , Oresnik Ivan , Atkins Craig A. , Layzell David B. 
Published: July 2002

Abstract
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% O2decreased 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.
Mutations Affecting Induction of Glycolytic and Fermentative Genes during Germination and Environmental Stresses in Arabidopsis1
Authors: Conley Terry R. , Peng Hsiao-Ping , Shih Ming-Che 
Published: July 2002

Abstract
Expression of the alcohol dehydrogenase gene (ADH) of Arabidopsis is known to be induced by environmental stresses and regulated developmentally. We used a negative-selection approach to isolate mutants that were defective in regulating the expression of theADH gene during seed germination; we then characterized three recessive mutants, aar1–1,aar1–2, and aar2–1, which belong to two complementation groups. In addition to their defects during seed germination, mutations in the AAR1 andAAR2 genes also affected anoxic and hypoxic induction ofADH and other glycolytic genes in mature plants. Theaar1 and aar2 mutants were also defective in responding to cold and osmotic stress. The two allelic mutantsaar1–1and aar1–2 exhibited different phenotypes under cold and osmotic stresses. Based on our results we propose that these mutants are defective in a late step of the signaling pathways that lead to increased expression of theADH gene and glycolytic genes.