bluuebunny/crossref_metadata_2025 huggingface dataset:
Dyslexia among Swedish prison inmates in relation to neuropsychology
and personality
Authors: JENSEN JIMMY , LINDGREN MAY , MEURLING ANN WIRSÉN , INGVAR DAVID H. , LEVANDER STEN
Published: July 2002

Several investigations have reported high frequencies
of reading and writing disabilities in criminal populations.
The aims of the present study were to assess the frequency
of dyslexia among Swedish prison inmates and to relate
dyslexia to other indices of neuropsychological functions.
Sixty-three prison inmates with Swedish as their native
language, age 19 to 57 years, were examined by interviews,
tests of academic achievement, and neuropsychological assessment.
Twenty-six (41%) were diagnosed as dyslexic. As expected,
the dyslexic group performed more poorly on verbal tests
as compared to the normal readers among the prison inmates,
but they also performed more poorly on tests measuring
nonverbal abilities. The dyslexic group had higher frequencies
of paranoid and avoidant personality disorders compared
to the nondyslexics. They also reported higher levels of
anxiety and suspicion and a lower degree of socialization.
Previous studies report low IQ to be associated with criminal
propensity, supporting the interpretation that a double
handicap (dyslexia and low IQ) increases the risk of entering
a criminal career and remaining in it. (JINS,
1999, 5, 452–461.)
Environmental consequences of agricultural commercialization in Asia
Authors: Pingali Prabhu L.
Published: July 2002

Agroindustrialization and agricultural commercialization are both consequences of economic growth and urbanization. Commercialization of agricultural systems leads to greater market orientation; progressive substitution out of non-traded inputs for purchased inputs; and the decline of integrated farming systems. Agricultural commercialization can have both negative and positive impacts on the natural resource base. Higher opportunity cost of labor increases farmer reliance on herbicides for weed control, primarily for the staple crops. The use of insecticides and fungicides could also rise, especially for high value fruit and vegetable crops. Increased use of agricultural chemicals could lead to higher environmental and human health risks. On the other hand, global integration and the consequent rationalization of agricultural policies could have significant environmental benefits, especially in terms of a reduced rate of salinity build up and ground water depletion in irrigated environments. The extent to which positive environmental effects manifest themselves depends on both macroeconomic and microeconomic policy reforms.
Wildlife, biodiversity and trade
Authors: BARBIER EDWARD B. , SCHULZ CARL-ERIK
Published: July 2002

This article develops a model of wild-resource exploitation that includes both the standard bioeconomic properties of growth and harvesting and a species-area relationship linked to habitat conversion. The model is developed for both a closed and an open economy. In the closed-economy model the characteristics of the long-run equilibrium are analysed in three versions of the model: the basic bioeconomic model, the inclusion of habitat conversion and the addition of biodiversity value. In the case of the open-economy model, we also examine the potential effects of trade interventions on the optimal exploitation of species and habitat conversion in the long run. The results confirm that the inclusion of habitat conversion as well as biodiversity value in a model of wild-resource exploitation yields significantly different outcomes than a basic bioeconomic model.
Applications of system dynamics modelling to computer music
Authors: WHALLEY IAN
Published: July 2002

Based on a composer's psycho-acoustic imagination or response to music, system dynamics modelling and simulation tools can be used as a scoring device to map the structural dynamic shape of interest of computer music compositions. The tools can also be used as a generator of compositional ideas reflecting thematic juxtaposition and emotional flux in musical narratives. These techniques allow the modelling of everyday narratives to provide a structural/metaphorical means of music composition based on archetypes that are shared with wider audiences. The methods are outlined using two examples.
Questions and Answers: An Invitation to Our Readers
Authors: Dowdney Linda , Scott Stephen
Published: July 2002

Clinicians in their practice often encounter
clinical problems on which they would
welcome a second opinion. For our
readers, we have brought together a group
of experienced practitioners who would be
happy to address readers' questions on
clinical matters that concern them. Topics
they would be happy to receive questions
on are listed below. We will publish selected
questions and answers together in one
issue. We hope readers will write in with
their own suggestions and answers for
publication in the following issue.
The ‘Total Transformation Alternation’ in the light of some Middle English data
Authors: CARROLL RUTH
Published: July 2002

The ‘Total Transformation Alternation’ (Levin, 1993: 57) has been attested in Modern English only with the Turn Verbs, verbs such as CHANGE, CONVERT, TRANSFORM, and TURN. This paper presents data showing the alternation also to be attested for some of the Middle English Cooking Verbs, including SĒTHEN ‘to simmer’. Since the alternation is not found with all the ME Cooking Verbs, this appears to be evidence against the correlation of lexical semantics with syntax. However, the paper goes on to demonstrate that this alternation is also available to ‘Reduction Verbs’, including Modern English REDUCE. Before REDUCE was used in this sense, Middle English verbs such as SĒTHEN could denote reduction in volume. When they were so used, they could appear in any of the syntactic constructions of this alternation. The paper concludes by reiterating the importance of investigating semantic components, rather than concentrating exclusively on verb classes.
‘Modal’ that as determiner and pronoun: the primacy of the cognitive-interactive dimension
Authors: Cornish Francis
Published: July 2002

In this article, I examine the ‘modal’ or ‘empathetic’ (Lyons, 1977: 677) use of the distal (or ‘nonproximal’) determiner/pronoun that: namely, where the intended referent may have just been evoked in the immediately prior discourse, but where the distal pronoun that, not the ‘in-focus’ it or the ‘activated’, proximal this is used. The rationale behind the choice of this particular type of indexical seems to be that the speaker is distancing him/herself from the referent, not wishing to ascribe actuality to it in the way that would be the case if either it or this were used instead. Examination of this particular value of that leads to the hypothesis that the principles underlying the choice of that as opposed to this or it generally are not derived ‘objectively’, as it were, from their situational use in terms of degrees of proximity of a referent or demonstratum to the speaker or hearer, nor primarily in terms of attention focus. They are, rather, social and cognitive, and play an important interactional role in the construction of discourse.
News About News: Information Arrival and Irreversible Investment
Authors: Drazen Allan , Sakellaris Plutarchos
Published: July 2002

We analyze how uncertainty about when information about future
returns to a project may be revealed affects investment. Whereas good
news about future returns boosts investment, good news about news
(that is, news that information may arrive sooner) is shown to
depress investment. We show that early revelation increases the value
of an irreversible investment project to a risk-neutral investor. Our
framework allows us to study irreversible investment projects whose
value has a time-variable volatility. We also consider how
heterogeneity of revelation information across firms may induce a
better-informed firm to share its information with competitors.
The neural basis of lexicon and grammar in first and second language: the declarative/procedural model
Authors: Ullman Michael T.
Published: July 2002

Theoretical and empirical aspects of the neural bases of the mental lexicon and the mental grammar in first and second language (L1 and L2) are discussed. It is argued that in L1, the learning, representation, and processing of lexicon and grammar depend on two well-studied brain memory systems. According to the declarative/procedural model, lexical memory depends upon declarative memory, which is rooted in temporal lobe structures, and has been implicated in the learning and use of fact and event knowledge. Aspects of grammar are subserved by procedural memory, which is rooted in left frontal/basal-ganglia structures, and has been implicated in the acquisition and expression of motor and cognitive skills and habits. This view is supported by psycholinguistic and neurolinguistic evidence. In contrast, linguistic forms whose grammatical computation depends upon procedural memory in L1 are posited to be largely dependent upon declarative/lexical memory in L2. They may be either memorized or constructed by explicit rules learned in declarative memory. Thus in L2, such linguistic forms should be less dependent on procedural memory, and more dependent on declarative memory, than in L1. Moreover, this shift to declarative memory is expected to increase with increasing age of exposure to L2, and with less experience (practice) with the language, which is predicted to improve the learning of grammatical rules by procedural memory. A retrospective examination of lesion, neuroimaging, and electrophysiological studies investigating the neural bases of L2 is presented. It is argued that the data from these studies support the predictions of the declarative/procedural model.
Universal bilingualism
Authors: Roeper Thomas
Published: July 2002

Lexically linked domains in language allow a speaker to formulate incompatible rules. How should they be represented theoretically? We argue that a speaker has a set of mini-grammars for different domains so that, in effect, every speaker is bilingual. It is argued that Tense or Agreement Checking, V-2 for quotation, and resumptive pronouns, all lead to bilingual representations. In addition, this perspective on Theoretical Bilingualism suggests that optionality and stages in the acquisition of an initial grammar should also be characterized as a form of bilingualism.
Nuclear reorganization and homologous chromosome pairing during meiotic prophase require C. elegans chk-2
Authors: MacQueen Amy J. , Villeneuve Anne M.
Published: July 2002

Analysis of mutants defective in meiotic chromosome pairing has uncovered a role for Caenorhabditis elegans chk-2 in initial establishment of pairing between homologous chromosomes during early meiotic prophase. chk-2 is also required for the major spatial reorganization of nuclei that normally accompanies the onset of pairing, suggesting a mechanistic coupling of these two events. Despite failures in pairing, nuclear reorganization, and crossover recombination, chk-2 mutants undergo many other aspects of meiotic chromosome morphogenesis and complete gametogenesis. Althoughchk-2 encodes a C. elegans ortholog of the Cds1/Chk2 checkpoint protein kinases, germ-line nuclei in chk-2 mutants are competent to arrest proliferation in response to replication inhibition and to trigger DNA damage checkpoint responses to ionizing radiation. However, chk-2 mutants are defective in triggering the pachytene DNA damage checkpoint in response to an intermediate block in the meiotic recombination pathway, suggesting thatchk-2 is required either for initiation of meiotic recombination or for monitoring a specific subset of DNA damage lesions. We propose that chk-2 functions during premeiotic S phase to enable chromosomes to become competent for subsequent meiotic prophase events and/or to coordinate replication with entry into prophase.
Time for a Unified System of Mutation Description and Reporting: A Review of Locus-Specific Mutation Databases
Authors: Claustres Mireille , Horaitis Ourania , Vanevski Marijana , Cotton Richard G.H.
Published: July 2002

Mutation databases of human genes are assuming an increasing importance in all areas of health care. In addition, more and more experts in the mutations and diseases of particular genes are curating published and unpublished mutations in locus-specific databases (LSDB). These databases contain such extensive information that they have become known as knowledge bases. We analyzed these databases and their content between June 21, 2001, and July 18, 2001. We were able to access 94 independent websites devoted to the documentation of mutation containing 262 LSDBs for study. We analyzed one LSDB from each of these websites (i.e., 94 LSDBs) for the presence or absence of 80 content criteria, as generally each gene in a multigene website documented the same criteria. No criterion studied gave unanimous agreement in every database. Twenty-two genes were represented by more than one LSDB. The number of mutations recorded, excluding p53, was 23,822 with 1518 polymorphisms. Fifty-four percent of the LSDBs studied were easy to use and 11% hard to follow; 73% of the databases were displayed through HTML. Three databases were found that were given a high score for ease of use and wealth of content. Thus, the study provided a strong case for uniformity of data to make the content maximally useful. In this direction, a hypothetical content for an ideal LSDB was derived. We also derived a community structure that would enhance the chances of mutation capture rather than being left unpublished in a patient's report. We hope the interested community and granting bodies will assist in achieving the vision of a public system that collects and displays all variants discovered.

[Supplemental material available online at http://www.genome.org]
Functional Properties and Regulatory Complexity of a MinimalRBCS Light-Responsive Unit Activated by Phytochrome, Cryptochrome, and Plastid Signals
Authors: Martı́nez-Hernández Aı́da , López-Ochoa Luisa , Argüello-Astorga Gerardo , Herrera-Estrella Luis
Published: July 2002

Light-inducible promoters are able to respond to a wide spectrum of light through multiple photoreceptor systems. Several cis-acting elements have been identified as components of light-responsive promoter elements; however, none of these regulatory elements by itself appears to be sufficient to confer light responsiveness; rather, the combination of at least two elements seems to be required. Using phylogenetic structural analysis, we have identified conserved DNA modular arrays (CMAs) associated with light-responsive promoter regions that have been conserved throughout the evolutionary radiation of angiosperms. Here, we report the functional characterization of CMA5, a native 52-bp fragment of theNicotiana plumbaginifolia rbcS 8B promoter, which contains an I- and a G-box cis-element. CMA5 behaves as a light-responsive minimal unit capable of activating a heterologous minimal promoter in a phytochrome-, cryptochrome-, and plastid-dependent manner. We also show that CMA5 light induction requires HY5 and that downstream negative regulators COP (constitutive photomorphogenic)/DET (de-etiolated) regulate its activity. Our results show that the simplest light-responsive promoter element from photosynthesis-associated genes described to date is the common target for different signals involved in light regulation. The possible mechanism involved in light-transcriptional regulation and tissue specificity of combinatorial elements units is discussed.
Expression, Activation, and Biochemical Properties of a Novel Arabidopsis Protein Kinase
Authors: Gong Deming , Gong Zhizhong , Guo Yan , Zhu Jian-Kang
Published: July 2002

An Arabidopsis SOS2 (salt overly sensitive 2)-like protein kinase gene, PKS6, was expressed in leaves, stems, and siliques, but not detectable in roots of adult plants; its expression in young seedlings was up-regulated by abscisic acid. To determine the biochemical properties of the PKS6 protein, we expressed the PKS6 coding sequence as a glutathione S-transferase fusion protein in Escherichia coli. The bacterially expressed glutathione S-transferase-PKS6 fusion protein was inactive in substrate phosphorylation. We have constructed constitutively active forms of PKS6 by either a deletion of its putative auto-inhibitory FISL motif (i.e. PKS6ΔF) or a substitution of threonine-178 with aspartic acid within the putative activation loop. We found that PKS6ΔF exhibited a strong preference for Mn2+ over Mg2+ as a divalent cation cofactor for kinase activity. PKS6ΔF displayed substrate specificity against three different peptide substrates and had an optimal pH of approximately 7.5 and temperature optimum of 30°C. The apparentK  m values for ATP and the preferred peptide substrate p3 of PKS6ΔF were determined to be 1.7 and 28.5 μm, respectively. These results provide significant insights into the regulation and biochemical properties of the protein kinase PKS6. In addition, the constitutively active, gain-of-function kinase mutants will be invaluable for future determination of the in planta function of PKS6.
Evidence Supporting a Role of Jasmonic Acid in Arabidopsis Leaf Senescence
Authors: He Yuehui , Fukushige Hirotada , Hildebrand David F. , Gan Susheng
Published: July 2002

In this work, the role of jasmonic acid (JA) in leaf senescence is examined. Exogenous application of JA caused premature senescence in attached and detached leaves in wild-type Arabidopsis but failed to induce precocious senescence of JA-insensitive mutantcoi1 plants, suggesting that the JA-signaling pathway is required for JA to promote leaf senescence. JA levels in senescing leaves are 4-fold higher than in non-senescing ones. Concurrent with the increase in JA level in senescing leaves, genes encoding the enzymes that catalyze most of the reactions of the JA biosynthetic pathway are differentially activated during leaf senescence in Arabidopsis, except for allene oxide synthase, which is constitutively and highly expressed throughout leaf development. Arabidopsis lipoxygenase 1 (cytoplasmic) expression is greatly increased but lipoxygenase 2 (plastidial) expression is sharply reduced during leaf senescence. Similarly,AOC1 (allene oxide cyclase 1),AOC2, and AOC3 are all up-regulated, whereas AOC4 is down-regulated with the progression of leaf senescence. The transcript levels of 12-oxo-PDA reductase 1 and 12-oxo-PDA reductase 3 also increase in senescing leaves, as does PED1 (encoding a 3-keto-acyl-thiolase for β-oxidation). This represents the first report, to our knowledge, of an increase in JA levels and expression of oxylipin genes during leaf senescence, and indicates that JA may play a role in the senescence program.
Protection by Isoprene against Singlet Oxygen in Leaves
Authors: Affek Hagit P. , Yakir Dan
Published: July 2002

Isoprene (2-methyl-1,3-butadiene) protection against effects of singlet oxygen was investigated in Myrtus communisand Rhamnus alaternus. In M. communis, singlet oxygen produced in the leaves by Rose Bengal (RB) led to a 65% decrease in net assimilation rates within 3 h, whereas isoprene emission rates showed either a 30% decrease at ambient CO2concentrations or a 70% increase under high CO2. In both cases, these changes led to an increase in calculated internal isoprene concentrations. The isoprene protection effect was directly demonstrated by fumigation of young (non-emitting) leaves, treated with RB or bromoxynil (simulating photoinhibition). There was 42% and 29% reduction in the damage to net assimilation compared with non-fumigated leaves for RB or bromoxynil, respectively. In R. alaternus, similar effects of RB on net assimilation were observed, and additional fluorescence measurements showed a significantly smaller decrease inF  v/F  m in isoprene-fumigated young leaves treated with RB (from 0.78 to 0.52), compared with non-fumigated leaves (from 0.77 to 0.27). The internal isoprene concentrations used in this study and possible rate of1O2 production in leaves indicate that the protective effects observed should be beneficial also under natural conditions.
Functional Expression of the Extraplastidial Arabidopsis thaliana Oleate Desaturase Gene (FAD2) in Saccharomyces cerevisiae
Authors: Covello P. S. , Reed D. W.
Published: July 2002

The functional expression in yeast of the Arabidopsis thaliana FAD2 gene, encoding the extraplastidial oleate desaturase (1-acyl-2-oleoyl-sn-glycero-3-phosphocholine [delta]12-desaturase) is reported. Dienoic fatty acids constituted up to 11% (w/w) of the total fatty acids in transformed Saccharomyces cerevisiae cells and were confirmed to be linoleic acid and [delta]9,[delta]12-hexadecadienoic acid by gas chromatography-mass spectrometry.
A Class IV Chitinase Is Highly Expressed in Grape Berries during Ripening
Authors: Robinson S. P. , Jacobs A. K. , Dry I. B.
Published: July 2002

Chitinase activity increased markedly at the onset of ripening in grape (Vitis vinifera L.) berries and continued to increase throughout the sugar accumulation phase of berry development. In contrast, β-1,3-glucanase activity was not detected in grape berries at any stage of development. Two closely related chitinase cDNAs (VvChi4A and VvChi4B) were cloned from grapes. Sequence and Southern analysis indicate that these two clones may represent alleles of the same gene. The predicted proteins are acidic and have a signal peptide followed by a cysteine-rich, chitin-binding domain and a catalytic region. An analysis of their sequences indicates that they are class IV chitinases. The deduced protein sequence of VvChi4A has a high level of identity with the 32- and 28-kD chitinases present as haze proteins in wine. Expression of VvChi4 was high in berries and low in flowers but was not detected in leaves, roots, or seeds. No expression was detected in berries 2 to 8 weeks postflowering, but expression was high 12 to 16 weeks postflowering, which coincided with sugar accumulation and an increase in chitinase activity. Constitutive expression of VvChi4 appears to be fruit-specific and induced at high levels in grapes during ripening.
Induction of 12-Oxo-Phytodienoic Acid in Wounded Plants and Elicited Plant Cell Cultures
Authors: Parchmann S. , Gundlach H. , Mueller M. J.
Published: July 2002

Jasmonic acid (JA) is rapidly biosynthesized from α--linolenic acid in plants upon contact with pathogens or wounding, and triggers gene activation, leading to the synthesis of defensive secondary metabolites and proteins. Despite the recent finding that its precursor, 12-oxo-phytodienoic acid (PDA), is a more powerful inducer of gene activation, interest has focused so far almost exclusively on JA. A validated negative chemical ionization-gas chromatography-mass spectrometry method has been developed that allows the simultaneous quantification of endogenous 12-oxo-PDA and JA in plant tissues. In six out of eight plant species tested maximal levels of 12-oxo-PDA exceeded peak levels of JA by approximately 3- to 5-fold after elicitation with a yeast cell wall preparation or when plants were wounded. These experiments support the hypothesis that 12-oxo-PDA acts as the predominant jasmonate signal in most plants, whereas JA remains an active metabolite of its precursor. Furthermore, JA but not 12-oxo-PDA was shown to be secreted into the medium from cultured plant cells, suggesting that JA may also act as an intercellular signal.
Light-Regulated Transcription of Genes Encoding Peridinin Chlorophyll a Proteins and the Major Intrinsic Light-Harvesting Complex Proteins in the DinoflagellateAmphidinium carterae Hulburt (Dinophycae)1
Authors: ten Lohuis Michael R. , Miller David J.
Published: July 2002

In the dinoflagellateAmphidinium carterae, photoadaptation involves changes in the transcription of genes encoding both of the major classes of light-harvesting proteins, the peridinin chlorophyll aproteins (PCPs) and the majora/c-containing intrinsic light-harvesting proteins (LHCs). PCP and LHC transcript levels were increased up to 86- and 6-fold higher, respectively, under low-light conditions relative to cells grown at high illumination. These increases in transcript abundance were accompanied by decreases in the extent of methylation of CpG and CpNpG motifs within or near PCP- and LHC-coding regions. Cytosine methylation levels in A. carterae are therefore nonstatic and may vary with environmental conditions in a manner suggestive of involvement in the regulation of gene expression. However, chemically induced undermethylation was insufficient in activating transcription, because treatment with two methylation inhibitors had no effect on PCP mRNA or protein levels. Regulation of gene activity through changes in DNA methylation has traditionally been assumed to be restricted to higher eukaryotes (deuterostomes and green plants); however, the atypically large genomes of dinoflagellates may have generated the requirement for systems of this type in a relatively “primitive” organism. Dinoflagellates may therefore provide a unique perspective on the evolution of eukaryotic DNA-methylation systems.
Purification and Characterization of a Low-Molecular-Weight Phospholipase A2 from Developing Seeds of Elm1
Authors: Ståhl Ulf , Ek Bo , Stymne Sten
Published: July 2002

Phospholipase A2(PLA2) was purified about 180,000 times compared with the starting soluble-protein extract from developing elm (Ulmus glabra) seeds. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis the purified fraction showed a single protein band with a mobility that corresponded to 15 kD, from which activity could be recovered. When analyzed by matrix-assisted laser-desorption ionization-time-of-flight mass spectrometry, the enzyme had a deduced mass of 13,900 D. A 53-amino acid-long N-terminal sequence was determined and aligned with other sequences, giving 62% identity to the deduced amino acid sequence of some rice (Oryza sativa) expressed sequence tag clones. The purified enzyme had an alkaline pH optimum and required Ca2+ for activity. It was unusually stable with regard to heat, acidity, and organic solvents but was sensitive to disulfide bond-reducing agents. The enzyme is a true PLA2, neither hydrolyzing the sn-1 position of phosphatidylcholine nor having any activity toward lysophosphatidylcholine or diacylglycerol. The biochemical data and amino acid sequence alignments indicate that the enzyme is related to the well-characterized family of animal secretory PLA2s and, to our knowledge, is the first plant enzyme of this type to be described.
The Superoxide Synthases of Rose Cells1
Authors: Murphy Terence M. , Vu Han , Nguyen Thuyhuong
Published: July 2002

In an effort to identify the enzymatic mechanism responsible for the synthesis of reactive oxygen species produced during the hypersensitive response, preparations of rose (Rosa damascena) cell plasma membranes, partially solubilized plasma membrane protein, and cytosol were assayed for the NADH- and NADPH-dependent synthesis of superoxide using assays for the reduction of cytochrome c (Cyt c), assays for the reduction of nitroblue tetrazolium, and assays for the chemiluminescence ofN,N′-dimethyl-9,9′-biacridium dinitrate (lucigenin). Each assay ascribed the highest activity to a different preparation: the Cyt c assay to cytosol, the nitroblue tetrazolium assay to plasma membrane, and the lucigenin assay to the partially solubilized plasma membrane protein (with NADH). This suggests that no two assays measure the same set of enzymes and that none of the assays is suitable for comparisons of superoxide synthesis among different cell fractions. With the plasma membrane preparation, the presence of large amounts of superoxide-dismutase-insensitive Cytc reductase confounded attempts to use Cytc to measure superoxide synthesis. With the partially solubilized membrane protein, direct reduction of lucigenin probably contributed to the chemiluminescence. Superoxide synthesis detected with lucigenin should be confirmed by superoxide-dismutase-sensitive Cyt c reduction.
In Vivo Ubiquinone Reduction Levels during Thermogenesis in Araceae1
Authors: Wagner Anneke M. , Wagner Marijke J. , Moore Anthony L.
Published: July 2002

In vivo ubiquinone (UQ) reduction levels were measured during the development of the inflorescences ofArum maculatum and Amorphophallus krausei. Thermogenesis in A. maculatum spadices appeared not to be confined to a single developmental stage, but occurred during various stages. The UQ pool in both A. maculatum and A. krausei appendices was approximately 90% reduced during thermogenesis. Respiratory characteristics of isolated appendix mitochondria did not change in the period around thermogenesis. Apparently, synthesis of the required enzyme capacity is regulated via a coarse control upon which a fine control of metabolism that regulates the onset of thermogenesis is imposed.
(+)-Abscisic Acid 8′-Hydroxylase Is a Cytochrome P450 Monooxygenase
Authors: Krochko Joan E. , Abrams Garth D. , Loewen Mary K. , Abrams Suzanne R. , Cutler Adrian J.
Published: July 2002

Abscisic acid (ABA) 8′-hydroxylase catalyzes the first step in the oxidative degradation of (+)-ABA. The development of a robust in vitro assay has now permitted detailed examination and characterization of this enzyme. Although several factors (buffer, cofactor, and source tissue) were critical in developing the assay, the most important of these was the identification of a tissue displaying high amounts of in vivo enzyme activity (A.J. Cutler, T.M. Squires, M.K. Loewen, J.J. Balsevich [1997] J Exp Bot 48: 1787–1795). (+)-ABA 8′-hydroxylase is an integral membrane protein that is localized to the microsomal fraction in suspension-cultured maize (Zea mays) cells. (+)-ABA metabolism requires both NADPH and molecular oxygen. NADH was not an effective cofactor, although there was substantial stimulation of activity (synergism) when it was included at rate-limiting NADPH concentrations. The metabolism of (+)-ABA was progressively inhibited at O2 concentrations less than 10% (v/v) and was very low (less than 5% of control) under N2. (+)-ABA 8′-hydroxylase activity was inhibited by tetcyclacis (50% inhibition at 10−6  m), cytochrome c (oxidized form), and CO. The CO inhibition was reversible by light from several regions of the visible spectrum, but most efficiently by blue and amber light. These data strongly support the contention that (+)-ABA 8′-hydroxylase is a cytochrome P450 monooxygenase.
12-Oxophytodienoate-10,11-Reductase: Occurrence of Two Isoenzymes of Different Specificity against Stereoisomers of 12-Oxophytodienoic Acid
Authors: Schaller Florian , Hennig Peter , Weiler Elmar W.
Published: July 2002

The reduction of 12-oxophytodienoic acid (OPDA) to 3-oxo-2(2′[Z]-pentenyl)-cyclopentane-1-octanoic acid is catalyzed by 12-oxophytodienoate-10,11-reductase (OPR). Analysis of the isomer preference of OPR has indicated that the activity is composed of two isoenzymes exhibiting different stereoselectivities. The two isoforms of OPR have been separated, using protein extracts of Rock Harlequin (Corydalis sempervirens) as the starting material. OPRI, the enzyme reported earlier from the same species and corresponding to the cloned OPR from Arabidopsis, utilized 9R,13R-OPDA >> 9S,13R-OPDA but not the 13S-configured isomers, whereas the new activity, OPRII, effectively reduced all four OPDA isomers, including the natural 9S,13S-OPDA (cis-[+]-OPDA). OPRII activity is characterized in detail. The enzyme's enzymatic, biochemical, and immunological properties prove that it is a close relative of OPRI. The roles of OPRI and OPRII in octadecanoid biology are discussed.
Heterologous Expression of Arabidopsis Phytochrome B in Transgenic Potato Influences Photosynthetic Performance and Tuber Development1
Authors: Thiele Alexandra , Herold Michael , Lenk Ingo , Quail Peter H. , Gatz Christiane
Published: July 2002

Transgenic potato (Solanum tuberosum) plants expressing Arabidopsis phytochrome B were characterized morphologically and physiologically under white light in a greenhouse to explore their potential for improved photosynthesis and higher tuber yields. As expected, overexpression of functional phytochrome B caused pleiotropic effects such as semidwarfism, decreased apical dominance, a higher number of smaller but thicker leaves, and increased pigmentation. Because of increased numbers of chloroplasts in elongated palisade cells, photosynthesis per leaf area and in each individual plant increased. In addition, photosynthesis was less sensitive to photoinactivation under prolonged light stress. The beginning of senescence was not delayed, but deceleration of chlorophyll degradation extended the lifetime of photosynthetically active plants. Both the higher photosynthetic performance and the longer lifespan of the transgenic plants allowed greater biomass production, resulting in extended underground organs with increased tuber yields.
Expression of a Gibberellin-Induced Leucine-Rich Repeat Receptor-Like Protein Kinase in Deepwater Rice and Its Interaction with Kinase-Associated Protein Phosphatase1
Authors: van der Knaap Esther , Song Wen-Yuan , Ruan De-Ling , Sauter Margret , Ronald Pamela C. , Kende Hans
Published: July 2002

We identified in deepwater rice (Oryza sativa L.) a gene encoding a leucine-rich repeat receptor-like transmembrane protein kinase, OsTMK(O.sativatransmembrane kinase). The transcript levels of OsTMK increased in the rice internode in response to gibberellin. Expression of OsTMKwas especially high in regions undergoing cell division and elongation. The kinase domain of OsTMK was enzymatically active, autophosphorylating on serine and threonine residues. A cDNA encoding a rice ortholog of a kinase-associated type 2C protein phosphatase (OsKAPP) was cloned. KAPPs are putative downstream components in kinase-mediated signal transduction pathways. The kinase interaction domain of OsKAPP was phosphorylated in vitro by the kinase domain of OsTMK. RNA gel-blot analysis indicated that the expression ofOsTMK and OsKAPP was similar in different tissues of the rice plant. In protein-binding assays, OsKAPP interacted with a receptor-like protein kinase, RLK5 of Arabidopsis, but not with the protein kinase domains of the rice and maize receptor-like protein kinases Xa21 and ZmPK1, respectively.
Biochemical Characterization of the Chlamydomonas reinhardtii α-1,4 Glucanotransferase Supports a Direct Function in Amylopectin Biosynthesis1
Authors: Colleoni Christophe , Dauvillée David , Mouille Gregory , Morell Matthew , Samuel Michael , Slomiany Marie-Christine , Liénard Luc , Wattebled Fabrice , d'Hulst Christophe , Ball Steven
Published: July 2002

Plant α-1,4 glucanotransferases (disproportionating enzymes, or D-enzymes) transfer glucan chains among oligosaccharides with the concomitant release of glucose (Glc). Analysis of Chlamydomonas reinhardtii sta11-1 mutants revealed a correlation between a D-enzyme deficiency and specific alterations in amylopectin structure and starch biosynthesis, thereby suggesting previously unknown biosynthetic functions. This study characterized the biochemical activities of the α-1,4 glucanotransferase that is deficient in sta11-1 mutants. The enzyme exhibited the glucan transfer and Glc production activities that define D-enzymes. D-enzyme also transferred glucans among the outer chains of amylopectin (using the polysaccharide chains as both donor and acceptor) and from malto-oligosaccharides into the outer chains of either amylopectin or glycogen. In contrast to transfer among oligosaccharides, which occurs readily with maltotriose, transfer into polysaccharide required longer donor molecules. All three enzymatic activities, evolution of Glc from oligosaccharides, glucan transfer from oligosaccharides into polysaccharides, and transfer among polysaccharide outer chains, were evident in a single 62-kD band. Absence of all three activities co-segregated with thesta11-1 mutation, which is known to cause abnormal accumulation of oligosaccharides at the expense of starch. To explain these data we propose that D-enzymes function directly in building the amylopectin structure.
Differential Induction of Plant Volatile Biosynthesis in the Lima Bean by Early and Late Intermediates of the Octadecanoid-Signaling Pathway
Authors: Koch Thomas , Krumm Thomas , Jung Verena , Engelberth Jürgen , Boland Wilhelm
Published: July 2002

Plants are able to respond to herbivore damage with de novo biosynthesis of an herbivore-characteristic blend of volatiles. The signal transduction initiating volatile biosynthesis may involve the activation of the octadecanoid pathway, as exemplified by the transient increase of endogenous jasmonic acid (JA) in leaves of lima bean (Phaseolus lunatus) after treatment with the macromolecular elicitor cellulysin. Within this pathway lima bean possesses at least two different biologically active signals that trigger different biosynthetic activities. Early intermediates of the pathway, especially 12-oxo-phytodienoic acid (PDA), are able to induce the biosynthesis of the diterpenoid-derived 4,8,12-trimethyltrideca-1,3,7,11-tetraene. High concentrations of PDA result in more complex patterns of additional volatiles. JA, the last compound in the sequence, lacks the ability to induce diterpenoid-derived compounds, but is highly effective at triggering the biosynthesis of other volatiles. The phytotoxin coronatine and amino acid conjugates of linolenic acid (e.g. linolenoyl-l-glutamine) mimic the action of PDA, but coronatine does not increase the level of endogenous JA. The structural analog of coronatine, the isoleucine conjugate of 1-oxo-indanoyl-4-carboxylic acid, effectively mimics the action of JA, but does not increase the level of endogenous JA. The differential induction of volatiles resembles previous findings on signal transduction in mechanically stimulated tendrils of Bryonia dioica.
The t-SNARE AtVAM3p Resides on the Prevacuolar Compartment in Arabidopsis Root Cells
Authors: Sanderfoot Anton A. , Kovaleva Valentina , Zheng Haiyan , Raikhel Natasha V.
Published: July 2002

Protein cargo is trafficked between the organelles of the endomembrane system inside transport vesicles, a process mediated by integral membrane proteins called SNAREs (soluble N-ethylmaleimide sensitive factor attachment protein receptors) that reside on the surface of the vesicle (v-SNAREs) and target membrane (t-SNAREs). In examining transport of cargo between the trans-Golgi network and the vacuole in Arabidopsis, we have previously characterized AtPEP12p as a t-SNARE residing on the prevacuolar compartment and AtVTI1a as a v-SNARE that interacts with AtPEP12p. Recently, we have begun to characterize AtVAM3p, another Arabidopsis t-SNARE that shows high sequence homology to AtPEP12p. We have found that AtVTI1a also interacts with AtVAM3p, suggesting a role for this t-SNARE in post-Golgi trafficking. AtVAM3p has been suggested to localize to the vacuolar membrane in Arabidopsis cells; however, using specific antisera and expression of epitope-tagged versions of each t-SNARE, we have discovered that AtVAM3p is found on the same prevacuolar structure as AtPEP12p in Arabidopsis root cells.
Genetic Engineering of Glycinebetaine Production toward Enhancing Stress Tolerance in Plants: Metabolic Limitations
Authors: Huang Jun , Hirji Rozina , Adam Luc , Rozwadowski Kevin L. , Hammerlindl Joe K. , Keller Wilf A. , Selvaraj Gopalan
Published: July 2002

Glycinebetaine (betaine) affords osmoprotection in bacteria, plants and animals, and protects cell components against harsh conditions in vitro. This and a compelling body of other evidence have encouraged the engineering of betaine production in plants lacking it. We have installed the metabolic step for oxidation of choline, a ubiquitous substance, to betaine in three diverse species, Arabidopsis, Brassica napus, and tobacco (Nicotiana tabacum), by constitutive expression of a bacterial choline oxidase gene. The highest levels of betaine in independent transgenics were 18.6, 12.8, and 13 μmol g−1 dry weight, respectively, values 10- to 20-fold lower than the levels found in natural betaine producers. However, choline-fed transgenic plants synthesized substantially more betaine. Increasing the choline supplementation further enhanced betaine synthesis, up to 613 μmol g−1 dry weight in Arabidopsis, 250 μmol g−1 dry weight in B. napus, and 80 μmol g−1 dry weight in tobacco. These studies demonstrate the need to enhance the endogenous choline supply to support accumulation of physiologically relevant amounts of betaine. A moderate stress tolerance was noted in some but not all betaine-producing transgenic lines based on relative shoot growth. Furthermore, the responses to stresses such as salinity, drought, and freezing were variable among the three species.
Spatial Regulation of Pectic Polysaccharides in Relation to Pit Fields in Cell Walls of Tomato Fruit Pericarp
Authors: Orfila Caroline , Knox J. Paul
Published: July 2002

Scanning electron microscopic examination of intact tomato (Lycopersicon esculentum) pericarp and isolated pericarp cell walls revealed pit fields and associated radiating ridges on the inner face of cell walls. In regions of the cell wall away from pit fields, equivalent ridges occurred in parallel arrays. Treatment of isolated cell walls with a calcium chelator resulted in the loss of these ridges, indicating that they contain homogalacturonan-rich pectic polysaccharides. Immunolabeling procedures confirmed that pit fields and associated radiating ridges contained homogalacturonan. Epitopes of the side chains of pectic polysaccharides were not located in the same regions as homogalacturonan and were spatially regulated in relation to pit fields. A (1→4)-β-galactan epitope was absent from cell walls in regions of pit fields. A (1→5)-α-arabinan epitope occurred most abundantly at the inner face of cell walls in regions surrounding the pit fields.
Import of Lyso-Phosphatidylcholine into Chloroplasts Likely at the Origin of Eukaryotic Plastidial Lipids
Authors: Mongrand Sébastien , Cassagne Claude , Bessoule Jean-Jacques
Published: July 2002

Plastids rely on the import of extraplastidial precursor for the synthesis of their own lipids. This key phenomenon in the formation of plastidial phosphatidylcholine (PC) and of the most abundant lipids on earth, namely galactolipids, is poorly understood. Various suggestions have been made on the nature of the precursor molecule(s) transferred to plastids, but despite general agreement that PC or a close metabolite plays a central role, there is no clear-cut answer to this question because of a lack of conclusive experimental data. We therefore designed experiments to discriminate between a transfer of PC, 1-acylglycero phosphorylcholine (lyso-PC), or glycerophosphorylcholine. After pulse-chase experiments with glycerol and acetate, plastids of leek (Allium porrum L.) seedlings were purified. The labels of the glycerol moiety and the sn-1- andsn-2-bound fatty acids of plastidial lipids were determined and compared with those associated with the extraplastidial PC. After import, plastid lipids contained the glycerol moiety and the fatty acids esterified to the sn-1 position originating from the extraplastidial PC; no import of sn-2-bound fatty acid was detected. These results rule out a transfer of PC or glycerophosphorylcholine, and are totally explained by an import of lyso-PC molecules used subsequently as precursor for the synthesis of eukaryotic plastid lipids.
Expression of Spinach Ascorbate Peroxidase Isoenzymes in Response to Oxidative Stresses
Authors: Yoshimura Kazuya , Yabuta Yukinori , Ishikawa Takahiro , Shigeoka Shigeru
Published: July 2002

We studied the response of each ascorbate peroxidase (APX) isoenzyme in spinach leaves under stress conditions imposed by high light intensity, drought, salinity, and applications of methyl viologen and abscisic acid. The steady-state transcript level of cytosolic APX remarkably increased in response to high-light stress and methyl viologen treatment, but not in response to the other stress treatments. The transcript levels of the chloroplastic (stromal and thylakoid-bound) and microbody-bound APX isoenzymes were not changed in response to any of the stress treatments. To explore the responses of the APX isoenzymes to photooxidative stress, the levels of transcript and protein and activities of each isoenzyme were studied during high-light stress and following its recovery. The cytosolic APX activity increased in parallel with transcript abundance during high-light stress, while the protein level was not altered. The other isoenzymes showed no significant changes in transcript and protein levels and activities, except for the gradual decrease in chloroplastic isoenzyme activities.
The Mechanic State of “Inner Tissue” in the Growing Zone of Sunflower Hypocotyls and the Regulation of Its Growth Rate Following Excision
Authors: Peters Winfried S. , Tomos A. Deri
Published: July 2002

Spontaneous growth of isolated inner tissue from the etiolated sunflower (Helianthus annuus L.) hypocotyl growing zone was investigated. A new preparation technique allowed measurements starting 3 s after excision. Elongation with respect to the turgescent and plasmolized state was quantified in terms of relative growth rates, facilitating comparison to growth in situ. Turgor and turgor-induced strain were determined. Overall longitudinal strain in inner tissues in situ was positive, indicating that compressive forces exerted by peripheral tissues are outweighed by turgor-dependent tensile stress. Inner tissue expansion following isolation depended on water uptake. Extreme plastic extension rates occurred immediately after excision, suggesting that mechanical parameters of inner tissue in situ cannot be extrapolated from the mechanics of excised sections. In the long term, excised inner tissue autonomously established values of turgor, turgor-induced strain, and relative growth rates similar to values in the living plant. These results support historic models of tissue cooperation during organ growth, in which inner tissues actively participate in the control of growth rates.
Cell-Specific and Conditional Expression of Caffeoyl-Coenzyme A-3-O-Methyltransferase in Poplar
Authors: Chen Cuiying , Meyermans Hugo , Burggraeve Bart , De Rycke Riet M. , Inoue Kentaro , De Vleesschauwer Vera , Steenackers Marijke , Van Montagu Marc C. , Engler Gilbert J. , Boerjan Wout A.
Published: July 2002

Caffeoyl coenzyme A-3-O-methyltransferase (CCoAOMT) plays an important role in lignin biosynthesis and is encoded by two genes in poplar (Populus trichocarpa). Here, we describe the expression pattern conferred by the two CCoAOMTpromoters when fused to the gus-coding sequence in transgenic poplar (Populus tremula × Populus alba). Both genes were expressed similarly in xylem and differentially in phloem. In xylem, expression was preferentially observed in vessels and contact rays, whereas expression was barely detectable in storage rays and fibers, suggesting different routes to monolignol biosynthesis in the different xylem types. Furthermore, after wounding, fungal infection, and bending, the expression of both genes was induced concomitantly with de novo lignin deposition. Importantly, upon bending and leaning of the stem, the cell-specific expression pattern was lost, and both genes were expressed in all cell types of the xylem. CCoAOMT promoter activity correlated well with the presence of the CCoAOMT protein, as shown by immunolocalization. These expression data may explain, at least in part, the heterogeneity in lignin composition that is observed between cell types and upon different environmental conditions.