bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distinct Sums Modulo n
and Tree Embeddings
Authors: KÉZDY ANDRÉ E. , SNEVILY HUNTER S. 
Published: July 2002

In this paper we are concerned with the following conjecture.Conjecture. For any positive integers n and k satisfying k < n, and any sequence a1, a2, … ak
of not necessarily distinct elements of Zn, there exists a permutation π ∈ Sk such that the
elements aπ(i)+i are all distinct modulo n.We prove this conjecture when 2k [les ] n+1. We then apply this result to tree embeddings.
Specifically, we show that, if T is a tree with n edges and radius r, then T decomposes Kt
for some t [les ] 32(2r+4)n2+1.
Slipperiness on roads –an expert system classification
Authors: Norrman Jonas 
Published: July 2002

AbstractA method for classifying different types of slipperiness on roads in Sweden is described. Using this method it is possible to survey road conditions in different areas and between different years to optimise winter road maintenance. Winter road maintenance in Sweden is generally undertaken by the national road administration to improve winter‐time road conditions, thereby keeping up the traffic flow and decreasing the accident rate. As a number of different types of slipperiness may develop on roads in winter, each due to a specific set of meteorological variables, maintenance work can be a complicated task. With the proposed classification method it becomes easier for the winter maintenance personnel to analyse information on road conditions and survey the distribution of road slipperiness in a region. The classification is performed with an expert system using meteorological data from the Swedish Road Weather Information System. The road condition is classified as good or as one out of ten different types of slipperiness on roads. Road conditions during three different winter periods are analysed. The results show that variations in climate produce substantial differences in annual road condition characteristics. The output from the expert system classifying road slipperiness is compared with recorded winter road maintenance reports. Maintenance action took place on 49% of all occasions when road conditions were classified as slippery. Copyright © 2000 Royal Meteorological Society
Assessing topographic exposure
Authors: Chapman Lee 
Published: July 2002

AbstractTopographic exposure is a variable which represents the degree of shelter afforded to a location. A detailed knowledge of exposure is useful for a wide variety of applications, ranging from the dynamics of drifting snow to the optimal location of wind‐farms. The degree of exposure can be calculated by considering the relative heights and distances of the horizon surrounding the point of study. Numerous approaches have been developed to measure this useful variable, from the early qualitative studies of wind‐shaped trees to Pyatts's quantitative TOPEX assessment. However, these studies have been superseded by the use of computers and in particular the application of digital terrain models. These provide a fast office‐based solution, virtually eliminating the need for fieldwork. Copyright © 2000 Royal Meteorological Society
Land‐use and meteorological aspects of the urban heat island
Authors: Unger J , Sümeghy Z , Gulyás Á , Bottyán Z , Mucsi L 
Published: July 2002

AbstractThis study examines the influence of urban and meteorological factors on the surface air temperature field of the medium‐sized city of Szeged, Hungary, using mobile and stationary measurements under different weather conditions between March and August 1999. This city, with a population of about 160 000, is situated on a low, flat flood plain. Efforts have been concentrated on investigating the maximum development of the urban heat island (UHI). Tasks include the determination of the spatial distribution of seasonal mean maximum UHI intensity and modelling of existing conditions in the period being studied. Multiple correlation and regression analyses are used to examine the effects of urban parameters (land‐use characteristics and distance from the city centre determined in a grid network) and of meteorological parameters (wind speed, temperature) on thermal conditions in the study area. The results indicate isotherms increasing in regular concentric shapes from the suburbs towards the inner urban areas where the mean maximum UHI intensity reaches more than 3°C in the studied periods. A strong relationship exists between urban thermal excess and distance, as well as built‐up ratio. In contrast, meteorological conditions do not have any significant effect on the UHI intensity at the time of its maximum development. Copyright © 2001 Royal Meteorological Society
Introduction to the environmental Kuznets curve special issue
Authors: BARBIER EDWARD B. 
Published: July 2002

This special issue is concerned with environmental Kuznets curves (EKC) - the hypothesis that there is an ‘inverted-U’ relationship between various indicators of environmental degradation and levels of per capita income. Explanations as to why environmental degradation should first increase then decline with income have focused on a number of underlying relationships, including:the effects of structural economic change on the use of the environment for resource inputs and to assimilate waste;the link between the demand for environmental quality and income;types of environmental degradation and ecological processes.
Characterization and Repeat Analysis of the Compact Genome of the Freshwater Pufferfish Tetraodon nigroviridis
Authors: Crollius H. Roest , Jaillon O. , Dasilva C. , Ozouf-Costaz C. , Fizames C. , Fischer C. , Bouneau L. , Billault A. , Quetier F. , Saurin W. , Bernot A. , Weissenbach J. 
Published: July 2002

Tetraodon nigroviridis is a freshwater pufferfish 20–30 million years distant from Fugu rubripes. The genome of both tetraodontiforms is compact, mostly because intergenic and intronic sequences are reduced in size compared to other vertebrate genomes. The previously uncharacterized Tetraodon genome is described here together with a detailed analysis of its repeat content and organization. We report the sequencing of 46 megabases of bacterial artificial chromosome (BAC) end sequences, which represents a random DNA sample equivalent to 13% of the genome. The sequence and location of rRNA gene clusters, centromeric and subtelocentric satellite sequences have been determined. Minisatellites and microsatellites have been cataloged and notable differences were observed in comparison with microsatellites from Fugu. The genome contains homologies to all known families of transposable elements, including Ty3-gypsy, Ty1-copia, Line retrotransposons, DNA transposons, and retroviruses, although their overall abundance is <1%. This structural analysis is an important prerequisite to sequencing the Tetraodongenome.[The sequence data described in this paper have been submitted to the EMBL data library under accession nos.AJ245809, AJ270048, AJ245808, AJ270029–AJ270047, DS42722 andAL305790–AL352938.]
A Large Population of Small Chloroplasts in Tobacco Leaf Cells Allows More Effective Chloroplast Movement Than a Few Enlarged Chloroplasts
Authors: Jeong Won Joong , Park Youn-Il , Suh KyeHong , Raven John A. , Yoo Ook Joon , Liu Jang Ryol 
Published: July 2002

Abstract
We generated transgenic tobacco (Nicotiana tabacumcv Xanthi) plants that contained only one to three enlarged chloroplasts per leaf mesophyll cell by introducingNtFtsZ1-2, a cDNA for plastid division. These plants were used to investigate the advantages of having a large population of small chloroplasts rather than a few enlarged chloroplasts in a leaf mesophyll cell. Despite the similarities in photosynthetic components and ultrastructure of photosynthetic machinery between wild-type and transgenic plants, the overall growth of transgenic plants under low- and high-light conditions was retarded. In wild-type plants, the chloroplasts moved toward the face position under low light and toward the profile position under high-light conditions. However, chloroplast rearrangement in transgenic plants in response to light conditions was not evident. In addition, transgenic plant leaves showed greatly diminished changes in leaf transmittance values under both light conditions, indicating that chloroplast rearrangement was severely retarded. Therefore, under low-light conditions the incomplete face position of the enlarged chloroplasts results in decreased absorbance of light energy. This, in turn, reduces plant growth. Under high-light conditions, the amount of absorbed light exceeds the photosynthetic utilization capacity due to the incomplete profile position of the enlarged chloroplasts, resulting in photodamage to the photosynthetic machinery, and decreased growth. The presence of a large number of small and/or rapidly moving chloroplasts in the cells of higher land plants permits more effective chloroplast phototaxis and, hence, allows more efficient utilization of low-incident photon flux densities. The photosynthetic apparatus is, consequently, protected from damage under high-incident photon flux densities.
Agrobacterium tumefaciens-Mediated Transformation of Maize Embryos Using a Standard Binary Vector System
Authors: Frame Bronwyn R. , Shou Huixia , Chikwamba Rachel K. , Zhang Zhanyuan , Xiang Chengbin , Fonger Tina M. , Pegg Sue Ellen K. , Li Baochun , Nettleton Dan S. , Pei Deqing , Wang Kan 
Published: July 2002

Abstract
We have achieved routine transformation of maize (Zea mays) using an Agrobacterium tumefaciensstandard binary (non-super binary) vector system. Immature zygotic embryos of the hybrid line Hi II were infected with A. tumefaciens strain EHA101 harboring a standard binary vector and cocultivated in the presence of 400 mg L−1 l-cysteine. Inclusion of l-cysteine in cocultivation medium lead to an improvement in transient β-glucuronidase expression observed in targeted cells and a significant increase in stable transformation efficiency, but was associated with a decrease in embryo response after cocultivation. The average stable transformation efficiency (no. of bialaphos-resistant events recovered per 100 embryos infected) of the present protocol was 5.5%. Southern-blot and progeny analyses confirmed the integration, expression, and inheritance of the bar andgus transgenes in R0, R1, and R2 generations of transgenic events. To our knowledge, this represents the first report in which fertile, stable transgenic maize has been routinely produced using an A. tumefaciensstandard binary vector system.
The Negatively Acting Factors EID1 and SPA1 Have Distinct Functions in Phytochrome A-Specific Light Signaling
Authors: Zhou Yong-Chun , Dieterle Monika , Büche Claudia , Kretsch Thomas 
Published: July 2002

AbstractEID1 (empfindlicher im dunkelroten Licht) and SPA1 (suppressor of phytochrome A[phyA]-105) function as negatively acting components in phyA-specific light signaling. Mutants in the respective genes led to very similar phenotypes under weak-light conditions. To examine whether both genes are functionally redundant, detailed physiological and genetic analyses were performed witheid1 and spa1 mutants isolated from the same wild-type background. Measurements of hypocotyl elongation, anthocyanin accumulation, and Lhcb1-transcript accumulation under different light treatments demonstrated that SPA1 has a strong influence on the regulation of very low fluence responses and a weaker influence on high-irradiance responses. In contrast, EID1 severely altered high-irradiance responses and caused almost no change on very low fluence responses. Analyses on eid1 phyA-105double mutants demonstrated that EID1 could not suppress the phenotype of the weak phyA allele under continuous far-red light. Measurements on eid1 spa1 double mutants exhibited a strong interference of both genes in the regulation of hypocotyl elongation. These results indicate that EID1 and SPA1 are involved in different but interacting phyA-dependent signal transduction chains.
Altering the Expression of the Chlorophyllase GeneATHCOR1 in Transgenic Arabidopsis Caused Changes in the Chlorophyll-to-Chlorophyllide Ratio
Authors: Benedetti Celso Eduardo , Arruda Paulo 
Published: July 2002

Abstract
The Arabidopsis gene ATHCOR1, which encodes the CORI1 (coronatine-induced) protein, was expressed in bacterial cells. Soluble recombinant CORI1 was purified and shown to possess chlorophyllase (Chlase) activity in vitro. To determine its activity in vivo, wild-type Arabidopsis and coi1 mutant, which lacksATHCOR1 transcripts, were transformed with sense and antisense forms of the gene. Wild-type and coi1 plants overexpressing ATHCOR1 showed increased contents of chlorophyllide (Chlide) without a substantial change in the total amount of the extractable chlorophyll (Chl). These plants presented high Chlide to Chl ratios in leaves, whereas antisense plants and nontransformed coi1 mutant showed undetectableATHCOR1 mRNA and significantly lower Chlide to Chl ratios, relative to wild-type control. Overexpression ofATHCOR1 caused an increased breakdown of Chla, as revealed by the Chlide a tob ratio, which was significantly higher in sense than wild-type, coi1 mutant, and antisense plants. This preferential activity of CORI1 toward Chl a was further supported by in vitro analyses using the purified protein. Increased Chlase activity was detected in developing flowers, which correlated to the constitutive expression of ATHCOR1 in this organ. Flowers of the antisense plant showed reduced Chlide to Chl ratio, suggesting a role of CORI1 in Chl breakdown during flower senescence. The results show that ATHCOR1 has Chlase activity in vivo, however, because coi1 flowers have no detectableATHCOR1 mRNA and present Chlide to Chl ratios comparable with the wild type, an additional Chlase is likely to be active in Arabidopsis. In accordance, transcripts of a second Arabidopsis Chlase gene, AtCLH2, were detected in both normal and mutant flowers.
Characterization of FRO1, a Pea Ferric-Chelate Reductase Involved in Root Iron Acquisition
Authors: Waters Brian M. , Blevins Dale G. , Eide David J. 
Published: July 2002

Abstract
To acquire iron, many plant species reduce soil Fe(III) to Fe(II) by Fe(III)-chelate reductases embedded in the plasma membrane of root epidermal cells. The reduced product is then taken up by Fe(II) transporter proteins. These activities are induced under Fe deficiency. We describe here the FRO1 gene from pea (Pisum sativum), which encodes an Fe(III)-chelate reductase. Consistent with this proposed role, FRO1 shows similarity to other oxidoreductase proteins, and expression of FRO1 in yeast conferred increased Fe(III)-chelate reductase activity. Furthermore,FRO1 mRNA levels in plants correlated with Fe(III)-chelate reductase activity. Sites of FRO1expression in roots, leaves, and nodules were determined.FRO1 mRNA was detected throughout the root, but was most abundant in the outer epidermal cells. Expression was detected in mesophyll cells in leaves. In root nodules, mRNA was detected in the infection zone and nitrogen-fixing region. These results indicate that FRO1 acts in root Fe uptake and they suggest a role in Fe distribution throughout the plant. Characterization of FRO1 has also provided new insights into the regulation of Fe uptake. FRO1expression and reductase activity was detected only in Fe-deficient roots of Sparkle, whereas both were constitutive in brzand dgl, two mutants with incorrectly regulated Fe accumulation. In contrast, FRO1 expression was responsive to Fe status in shoots of all three plant lines. These results indicate differential regulation of FRO1 in roots and shoots, and improper FRO1 regulation in response to a shoot-derived signal of iron status in the roots of thebrz and dgl mutants.
Overexpression of Polygalacturonase in Transgenic Apple Trees Leads to a Range of Novel Phenotypes Involving Changes in Cell Adhesion
Authors: Atkinson Ross G. , Schröder Roswitha , Hallett Ian C. , Cohen Daniel , MacRae Elspeth A. 
Published: July 2002

AbstractPolygalacturonases (PGs) cleave runs of unesterified GalUA that form homogalacturonan regions along the backbone of pectin. Homogalacturonan-rich pectin is commonly found in the middle lamella region of the wall where two adjacent cells abut and its integrity is important for cell adhesion. Transgenic apple (Malus domestica Borkh. cv Royal Gala) trees were produced that contained additional copies of a fruit-specific apple PG gene under a constitutive promoter. In contrast to previous studies in transgenic tobacco (Nicotiana tabacum) where PG overexpression had no effect on the plant (K.W. Osteryoung, K. Toenjes, B. Hall, V. Winkler, A.B. Bennett [1990] Plant Cell 2: 1239–1248), PG overexpression in transgenic apple led to a range of novel phenotypes. These phenotypes included silvery colored leaves and premature leaf shedding due to reduced cell adhesion in leaf abscission zones. Mature leaves had malformed and malfunctioning stomata that perturbed water relations and contributed to a brittle leaf phenotype. Chemical and ultrastructural analyses were used to relate the phenotypic changes to pectin changes in the leaf cell walls. The modification of apple trees by a single PG gene has offered a new and unexpected perspective on the role of pectin and cell wall adhesion in leaf morphology and stomatal development.
A Flooding-Induced Xyloglucan Endo-Transglycosylase Homolog in Maize Is Responsive to Ethylene and Associated with Aerenchyma
Authors: Saab I. N. , Sachs M. M. 
Published: July 2002

Abstract
Development of aerenchyma (soft cortical tissue with large intercellular air spaces) in flooded plants results from cell-wall hydrolysis and eventual cell lysis and is promoted by endogenous ethylene. Despite its adaptive significance, the molecular mechanisms behind aerenchyma development remain unknown. We recently isolated a flooding-induced maize (Zea mays L.) gene (wusl1005[gfu]; abbreviated as 1005) encoding a homolog of xyloglucan endo-transglycosylase (XET), a putative cell-wall-loosening enzyme active during germination, expansion, and fruit softening. XET and related enzymes may also be involved in cell-wall metabolism during flooding-induced aerenchyma development. Under flooding, 1005 mRNA accumulated in root and mesocotyl locations that subsequently exhibited aerenchyma development and reached maximum levels within 12 h of treatment. Aerenchyma development was observed in the same locations by 48 h of treatment. Treatment with the ethylene synthesis inhibitor (aminooxy)acetic acid (AOA), which prevented cortical air space formation under flooding, almost completely inhibited 1005 mRNA accumulation in both organs. AOA treatment had little effect on the accumulation of mRNA encoded by adh1, indicating that it did not cause general suppression of flooding-responsive genes. Additionally, ethylene treatment under aerobic conditions resulted in aerenchyma development as well as induction of 1005 in both organs. These results indicate that 1005 is responsive to ethylene. Treatment with anoxia, which suppresses ethylene accumulation and aerenchyma development, also resulted in 1005 induction. However, in contrast to flooding, AOA treatment under anoxia did not affect 1005 mRNA accumulation, indicating that 1005 is induced via different mechanisms under flooding (hypoxia) and anoxia.
Molecular Characterization of Berberine Bridge Enzyme Genes from Opium Poppy
Authors: Facchini P. J. , Penzes C. , Johnson A. G. , Bull D. 
Published: July 2002

Abstract
In Papaver somniferum (opium poppy) and related species, (S)-reticuline serves as a branch-point intermediate in the biosynthesis of numerous isoquinoline alkaloids. The berberine bridge enzyme (BBE) ([S]-reticuline:oxygen oxidoreductase [methylene bridge forming], EC 1.5.3.9) catalyzes the stereospecific conversion of the N-methyl moiety of (S)-reticuline into the berberine bridge carbon of (S)-scoulerine and represents the first committed step in the pathway leading to the antimicrobial alkaloid sanguinarine. Three unique genomic clones (bbe1, bbe2, and bbe3) similar to a BBE cDNA from Eschscholtzia californica (California poppy) were isolated from opium poppy. Two clones (bbe2 and bbe3) contained frame-shift mutations of which bbe2 was identified as a putative, nonexpressed pseudogene by RNA blot hybridization using a gene-specific probe and by the lack of transient expression of a chimeric gene fusion between the bbe2 5[prime] flanking region and a β-glucuronidase reporter gene. Similarly, bbe1 was shown to be expressed in opium poppy plants and cultured cells. Genomic DNA blot-hybridization data were consistent with a limited number of bbe homologs. RNA blot hybridization showed that bbe genes are expressed in roots and stems of mature plants and in seedlings within 3 d after germination. Rapid and transient BBE mRNA accumulation also occurred after treatment with a fungal elicitor or with methyl jasmonate. However, sanguinarine was found only in roots, seedlings, and fungal elicitor-treated cell cultures.
Characterization of Maize Elongation Factor 1A and Its Relationship to Protein Quality in the Endosperm
Authors: Sun Y. , Carneiro N. , Clore A. M. , Moro G. L. , Habben J. E. , Larkins B. A. 
Published: July 2002

Abstract
The protein synthesis elongation factor 1A (eEF1A) is a multifunctional protein in eukaryotic cells. In maize (Zea mays L.) endosperm eEF1A co-localizes with actin around protein bodies, and its accumulation is highly correlated with the protein-bound lysine (Lys) content. We purified eEF1A from maize kernels by ammonium sulfate precipitation, ion-exchange, and chromatofocusing. The identity of the purified protein was confirmed by microsequencing of an endoproteinase glutamic acid-C fragment and by its ability to bundle actin. Using purified eEF1A as a standard, we found that this protein contributes 0.4% of the total protein in W64A+ endosperm and approximately 1% of the protein in W64Ao2. Because eEF1A contains 10% Lys, it accounts for 2.2% of the total Lys in W64A+ and 2.3% of the Lys in W64Ao2. However, its concentration predicts 90% of the Lys found in endosperm proteins of both genotypes, indicating that eEF1A is a key component of the group of proteins that determines the nutritional quality of the grain. This notion is further supported by the fact that in floury2, another high-Lys mutant, the content of eEF1A increases with the dosage of the floury2 gene. These data provide the biochemical basis for further investigation of the relationship between eEF1A content and the nutritional quality of cereals.
ADP-Glucose Pyrophosphorylase Is Localized to Both the Cytoplasm and Plastids in Developing Pericarp of Tomato Fruit1
Authors: Chen Bing-Yuan , Wang Yi , Janes Harry W. 
Published: July 2002

AbstractThe intracellular location of ADP-glucose pyrophosphorylase (AGP) in developing pericarp of tomato (Lycopersicon esculentum Mill) has been investigated by immunolocalization. With the use of a highly specific anti-tomato fruit AGP antibody, the enzyme was localized in cytoplasm as well as plastids at both the light and electron microscope levels. The immunogold particles in plastids were localized in the stroma and at the surface of the starch granule, whereas those in the cytoplasm occurred in cluster-like patterns. Contrary to the fruit, the labeling in tomato leaf cells occurred exclusively in the chloroplasts. These data demonstrate that AGP is localized to both the cytoplasm and plastids in developing pericarp cells of tomato.