bluuebunny/crossref_metadata_2025_split huggingface dataset:
Release probability is regulated by the size of the readily releasable vesicle pool at excitatory synapses in hippocampus
Authors: Dobrunz Lynn E. 
Published: September 2002

AbstractSynapses in the central nervous system can be very unreliable: stimulation of an individual synapse by an action potential often does not lead to release of neurotransmitter. The probability of transmitter release is not always the same, however, which enables the average strength of synaptic transmission to be regulated by modulation of release probability. Release probability is believed to be determined by the number of fusion competent vesicles (the readily releasable vesicle pool) and the release probability per vesicle. Studies from single synapses have shown that release probability correlates with the size of the readily releasable pool of vesicles across the population of excitatory CA3–CA1 synapses, both in hippocampal slices and in cultured cells. Here I present evidence that the same relationship exists between release probability and the size of the readily releasable vesicle pool within individual synapses, further suggesting that the size of the readily releasable pool helps determine release probability. In addition, using a simple model, I examine how both the number of readily releasable vesicles and the average release probability per vesicle change during trains of high frequency stimulation, and present evidence for non‐uniformity of the release probability among vesicles.
The E.K. Shriver Center at the University of Massachusetts Medical School
Authors: McIlvane W.J. 
Published: September 2002

AbstractThe UMMS Shriver Center promotes an understanding of typical and atypical neurological, cognitive, and behavioral development, emphasizing mental retardation. To accomplish its mission, the Center conducts basic and applied research to determine the biological and environmental factors that influence development and provides training and service programs that directly benefit people with developmental disabilities and their families.
Experimental study of a vortex in a magnetic field
Authors: SREENIVASAN BINOD , ALBOUSSIÈRE THIERRY 
Published: September 2002

It is well-known that magnetohydrodynamic (MHD) flows behave differently from
conventional fluid flows in two ways: the magnetic field makes the flow field
anisotropic in the sense that it becomes independent of the coordinate parallel
to the field; and the flow of liquid across the field lines induces an electric current,
leading to ohmic damping. In this paper, an experimental study is presented of the
long-time decay of an initially three-dimensional flow structure subject to a steady
magnetic field, when the ratio of the electromagnetic Lorentz forces to the nonlinear
inertial forces, quantified by the magnetic interaction parameter, N0, takes large as
well as moderate values. This investigation is markedly different from previous studies
on quasi-two-dimensional MHD flows in thin layers of conducting fluids, where only
Hartmann layer friction held the key to the dissipation of the flow.The initial ‘linear’ phase of decay of an MHD flow, characterized by dominant
Lorentz forces and modelled extensively in the literature, has been observed for the
first time in a laboratory experiment. Further, when N0 is large compared to unity, a
distinct regime of decay of a vortex follows this linear phase. This interesting trend
can be explained in terms of the behaviour of the ratio of the actual magnitudes
of the Lorentz to the nonlinear inertial forces – the true interaction parameter – which
decreases to a constant of order unity towards the end of the linear phase of decay,
and remains invariant during a subsequent ‘nonlinear’ phase.
Surviving Economic Crises in Southeast Asia and Southern China: The History of Eu Yan Sang Business Conglomerates in Penang, Singapore and Hong Kong
Authors: Chung Stephanie Po-Yin 
Published: September 2002

Prologue: Business Environment and Economic BehaviorFor more than two decades, sociologists, historians and economic geographers have produced many case studies on Chinese family businesses. A major consensus of these works suggests that ‘networking’, especially ethnic and familial, is extremely important to Chinese businesses. Various models and theories have been employed to explain this phenomenon. Notable among these explanations is the idea of Chinese entrepreneurship. According to this idea, such ethnicity-based groups as the Cantonese and the Fujianese (of the provinces of Guangdong and Fujian), are regarded to be culturally oriented towards business entrepreneurship and the cultivation of business networks. Before the outbreak of the Asian economic crisis in October 1997, many researchers believed that ‘Chinese entrepreneurship’ and the ‘business culture of networking’ contributed to the success of Chinese businesses in Asia (especially in the ‘Four Little Dragons’ of coastal Asia). For example, Confucian ethics and its emphasis on familial and ethnic networks is regarded as an asset for business expansion by Chinese international enterprises based in Hong Kong, Taiwan and Singapore. After the outbreak of the crisis, more research on the nature of Chinese entrepreneurship and the culture of networking was carried out. This research started from a different angle. The reliance on politically secured economic privileges (i.e.; nepotism), was identified as a defect of networking and thus, one of the major underlying causes of the crisis. The claim that the culture of networking contributes to business success actually offers a readily available explanation for its failure as well (see for examples Redding, 1990; Yeung, 1997; Yeung, 1998).
April McMahon (2000). Change, chance, and optimality. Oxford: Oxford University Press. Pp. x+201.
Authors: Kirchner Robert 
Published: September 2002

It is generally acknowledged, by both its proponents and detractors, that
Optimality Theory has provoked a reexamination, in recent years, of the role of
functional considerations, and their typological reflexes, in phonological theory.
April McMahon's Change, chance, and optimality attempts an in-depth examination of this issue, particularly from the perspective of the relation between
synchrony and diachrony in linguistic theory.
The issue, and OT's general stance towards it, are summarised by Prince &
Smolensky (1993: 198):One might feel compelled to view a grammar as a more-or-less arbitrary assortment of
formal rules, where the principles that the rules subserve (the ‘laws’) are placed entirely
outside the grammar, beyond the purview of formal or theoretical analysis, inert but
admired. It is not unheard of to conduct phonology in this fashion. We urge a reassessment of this essentially formalist position. If phonology is separated from the
principles of well-formedness (the ‘laws’) that drive it, the resulting loss of constraint and
theoretical depth will mark as major defeat for the enterprise. The danger, therefore, lies
in the other direction: clinging to a conception of Universal Grammar as little more than
a loose organizing framework for grammars. A much stronger stance, in accord with the
thrust of recent work, is available. When the scalar and the gradient are recognized and
brought within the purview of theory, Universal Grammar can supply the very substance
from which grammars are built: a set of highly general constraints which, through
ranking, interact to produce the elaborate particularity of individual languages.
Numerical simulation of a super cyclonic storm, Orissa 1999: impact of initial conditions
Authors: Trivedi D K , Sanjay J , Singh S S 
Published: September 2002

AbstractNumerical simulations are performed using the Penn State University/ National Center for Atmospheric Research Mesoscale Model (MM5) to study the impact of initial conditions on the super cyclone which hit the coast of Orissa in 1999. Because analysis of the cyclone's circulation was inadequate in the initial fields owing to the coarse resolution of the operational analysis systems and sparse oceanic data coverage, synthetic vortex data were generated using empirical relations and used in the analysis. Four‐dimensional data assimilation is performed in order to assimilate the synthetic vortex in the initial stage to the model.Considerable improvement in the track is obtained by using the synthetic vortex. With better specification of the initial vortex structure, the model successfully simulated the typical tropical cyclone characteristics, such as asymmetries in the wind field: the strongest winds occurred in the east and close to the cyclone's centre, strong wind gradients were found between the centre and the maximum wind region, and there was a slow decrease in wind speed up to the middle troposphere. Despite failing to produce the intense pressure drop observed for this cyclone, the model shows much better cyclone development with enhanced initial condition than the analysis. Copyright © 2002 Royal Meteorological Society.
Special issue on
‘Program development’
Authors: BRUYNOOGHE MAURICE , LAU KUNG-KIU 
Published: September 2002

This special issue marks the tenth anniversary of the LOPSTR workshop. LOPSTR
started in 1991 as a workshop on Logic Program Synthesis and Transformation, but
later it broadened its scope to logic-based Program Development in general.The motivating force behind LOPSTR has been a belief that declarative paradigms
such as logic programming are better suited to program development tasks than
traditional non-declarative ones such as the imperative paradigm. Specification,
synthesis, transformation or specialisation, analysis, verification and debugging can
all be given logical foundations, thus providing a unifying framework for the whole
development process.In the past ten years or so, such a theoretical framework has indeed begun to
emerge. Even tools have been implemented for analysis, verification and specialisation.
However, it is fair to say that so far the focus has largely been on
programming-in-the-small. So the future challenge is to apply or extend these
techniques to programming-in-the-large, in order to tackle software engineering in
the real world.
Arabinoxylan Biosynthesis in Wheat. Characterization of Arabinosyltransferase Activity in Golgi Membranes
Authors: Porchia Andrea Celia , Sørensen Susanne Oxenbøll , Scheller Henrik Vibe 
Published: September 2002

Abstract
Arabinoxylan arabinosyltransferase (AX-AraT) activity was investigated using microsomes and Golgi vesicles isolated from wheat (Triticum aestivum) seedlings. Incubation of microsomes with UDP-[14C]-β-l-arabinopyranose resulted in incorporation of radioactivity into two different products, although most of the radioactivity was present in xylose (Xyl), indicating a high degree of UDP-arabinose (Ara) epimerization. In isolated Golgi vesicles, the epimerization was negligible, and incubation with UDP-[14C]Ara resulted in formation of a product that could be solubilized with proteinase K. In contrast, when Golgi vesicles were incubated with UDP-[14C]Ara in the presence of unlabeled UDP-Xyl, the product obtained could be solubilized with xylanase, whereas proteinase K had no effect. Thus, the AX-AraT is dependent on the synthesis of unsubstituted xylan acting as acceptor. Further analysis of the radiolabeled product formed in the presence of unlabeled UDP-Xyl revealed that it had an apparent molecular mass of approximately 500 kD. Furthermore, the total incorporation of [14C]Ara was dependent on the time of incubation and the amount of Golgi protein used. AX-AraT activity had a pH optimum at 6, and required the presence of divalent cations, Mn2+ being the most efficient. In the absence of UDP-Xyl, a single arabinosylated protein with an apparent molecular mass of 40 kD was radiolabeled. The [14C]Ara labeling became reversible by adding unlabeled UDP-Xyl to the reaction medium. The possible role of this protein in arabinoxylan biosynthesis is discussed.
Cell-Specific Expression of Homospermidine Synthase, the Entry Enzyme of the Pyrrolizidine Alkaloid Pathway inSenecio vernalis, in Comparison with Its Ancestor, Deoxyhypusine Synthase
Authors: Moll Stefanie , Anke Sven , Kahmann Uwe , Hänsch Robert , Hartmann Thomas , Ober Dietrich 
Published: September 2002

AbstractPyrrolizidine alkaloids (PAs) are constitutive plant defense compounds with a sporadic taxonomic occurrence. The first committed step in PA biosynthesis is catalyzed by homospermidine synthase (HSS). Recent evidence confirmed that HSS evolved by gene duplication from deoxyhypusine synthase (DHS), an enzyme involved in the posttranslational activation of the eukaryotic translation initiation factor 5A. To better understand the evolutionary relationship between these two enzymes, which are involved in completely different biological processes, we studied their tissue-specific expression. RNA-blot analysis, reverse transcriptase-PCR, and immunolocalization techniques demonstrated that DHS is constitutively expressed in shoots and roots of Senecio vernalis (Asteraceae), whereas HSS expression is root specific and restricted to distinct groups of endodermis and neighboring cortex cells located opposite to the phloem. All efforts to detect DHS by immunolocalization failed, but studies with promoter-β-glucuronidase fusions confirmed a general expression pattern, at least in young seedlings of tobacco (Nicotiana tabacum). The expression pattern for HSS differs completely from its ancestor DHS due to the adaptation of HSS to the specific requirements of PA biosynthesis.
Inositol Phospholipid Metabolism in Arabidopsis. Characterized and Putative Isoforms of Inositol Phospholipid Kinase and Phosphoinositide-Specific Phospholipase C
Authors: Mueller-Roeber Bernd , Pical Christophe 
Published: September 2002

AbstractPhosphoinositides (PIs) constitute a minor fraction of total cellular lipids in all eukaryotic cells. They fulfill many important functions through interaction with a wide range of cellular proteins. Members of distinct inositol lipid kinase families catalyze the synthesis of these phospholipids from phosphatidylinositol. The hydrolysis of PIs involves phosphatases and isoforms of PI-specific phospholipase C. Although our knowledge of the roles played by plant PIs is clearly limited at present, there is no doubt that they are involved in many physiological processes during plant growth and development. In this review, we concentrate on inositol lipid-metabolizing enzymes from the model plant Arabidopsis for which biochemical characterization data are available, namely the inositol lipid kinases and PI-specific phospholipase Cs. The biochemical properties and structure of characterized and genome-predicted isoforms are presented and compared with those of the animal enzymes to show that the plant enzymes have some features clearly unique to this kingdom.
Tandemly Duplicated Safener-Induced Glutathione S-Transferase Genes from Triticum tauschii Contribute to Genome- and Organ-Specific Expression in Hexaploid Wheat
Authors: Xu Fangxiu , Lagudah Evans S. , Moose Stephen P. , Riechers Dean E. 
Published: September 2002

Abstract
Glutathione S-transferase (GST) gene expression was examined in several Triticum species, differing in genome constitution and ploidy level, to determine genome contribution to GST expression in cultivated, hexaploid bread wheat (Triticum aestivum). Two tandemly duplicated tau class GST genes (TtGSTU1 and TtGSTU2) were isolated from a single bacterial artificial chromosome clone in a library constructed from the diploid wheat and D genome progenitor to cultivated wheat, Triticum tauschii. The genes are very similar in genomic structure and their encoded proteins are 95% identical. Gene-specific reverse transcriptase-polymerase chain reaction analysis revealed differential transcript accumulation ofTtGSTU1 and TtGSTU2 in roots and shoots. Expression of both genes was induced by herbicide safeners, 2,4-dichlorophenoxyacetic acid and abscisic acid, in the shoots of T. tauschii; however, expression ofTtGSTU1 was always higher than TtGSTU2. In untreated seedlings, TtGSTU1 was expressed in both shoots and roots, whereas TtGSTU2 expression was only detected in roots. RNA gel-blot analysis of ditelosomic, aneuploid lines that are deficient for 6AS, 6BS, or 6DS chromosome arms of cultivated, hexaploid bread wheat showed differential genome contribution to safener-induced GST expression in shoots compared with roots. The GST genes from the D genome of hexaploid wheat contribute most to safener-induced expression in the shoots, whereas GSTs from the B and D genomes contribute to safener-induced expression in the roots.
Characterization of a Strong Dominantphytochrome AMutation Unique to Phytochrome A Signal Propagation
Authors: Fry Rebecca C. , Habashi Jessica , Okamoto Haruko , Deng Xing Wang 
Published: September 2002

AbstractHere, we report the isolation and characterization of a strong dominant-negative phytochrome A(phyA) mutation (phyA-300D) in Arabidopsis. This mutation carries a single amino acid substitution at residue 631, from valine to methionine (V631M), in the core region within the C-terminal half of PHYA. This PHYA core region contains two protein-interactive motifs, PAS1 and PAS2. Val-631 is located within the PAS1 motif. The phyA-V631M mutant protein is photochemically active and accumulates to a level similar to wild type in dark-grown seedlings. Overexpression of PHYA-V631M in a wild-type background results in a dominant-negative interference with endogenous wild-type phyA, whereas PHYA-V631M in aphyA null mutant background is inactive. To investigate the specificity of this mutation within the phytochrome family, the corresponding amino acid substitution (V664M) was created in the PHYTOCHROME B (PHYB) polypeptide. We found that the phyB-V664M mutant protein is physiologically active in phyB mutant and causes no interfering effect in a wild-type background. Together, our results reveal a unique feature in phyA signal propagation through the C-terminal core region.
The Circadian Clock That Controls Gene Expression in Arabidopsis Is Tissue Specific
Authors: Thain Simon C. , Murtas Giovanni , Lynn James R. , McGrath Robert. B. , Millar Andrew J. 
Published: September 2002

AbstractThe expression of CHALCONE SYNTHASE(CHS) expression is an important control step in the biosynthesis of flavonoids, which are major photoprotectants in plants. CHS transcription is regulated by endogenous programs and in response to environmental signals. Luciferase reporter gene fusions showed that the CHS promoter is controlled by the circadian clock both in roots and in aerial organs of transgenic Arabidopsis plants. The period of rhythmicCHS expression differs from the previously described rhythm of chlorophyll a/b-binding protein (CAB) gene expression, indicating thatCHS is controlled by a distinct circadian clock. The difference in period is maintained in the wild-type Arabidopsis accessions tested and in the de-etiolated 1 andtiming of CAB expression 1 mutants. These clock-affecting mutations alter the rhythms of both CABand CHS markers, indicating that a similar (if not identical) circadian clock mechanism controls these rhythms. The distinct tissue distribution of CAB andCHS expression suggests that the properties of the circadian clock differ among plant tissues. Several animal organs also exhibit heterogeneous circadian properties in culture but are believed to be synchronized in vivo. The fact that differing periods are manifest in intact plants supports our proposal that spatially separated copies of the plant circadian clock are at most weakly coupled, if not functionally independent. This autonomy has apparently permitted tissue-specific specialization of circadian timing.
Short-Term Boron Deprivation Inhibits Endocytosis of Cell Wall Pectins in Meristematic Cells of Maize and Wheat Root Apices
Authors: Yu Qin , Hlavacka Andrej , Matoh Toru , Volkmann Dieter , Menzel Diedrik , Goldbach Heiner E. , Baluška František 
Published: September 2002

AbstractBy using immunofluorescence microscopy, we observed rapidly altered distribution patterns of cell wall pectins in meristematic cells of maize (Zea mays) and wheat (Triticum aestivum) root apices. This response was shown for homogalacturonan pectins characterized by a low level (up to 40%) of methylesterification and for rhamnogalacturonan II pectins cross-linked by a borate diol diester. Under boron deprivation, abundance of these pectins rapidly increased in cell walls, whereas their internalization was inhibited, as evidenced by a reduced and even blocked accumulation of these cell wall pectins within brefeldin A-induced compartments. In contrast, root cells of species sensitive to the boron deprivation, like zucchini (Cucurbita pepo) and alfalfa (Medicago sativa), do not internalize cell wall pectins into brefeldin A compartments and do not show accumulation of pectins in their cell walls under boron deprivation. For maize and wheat root apices, we favor an apoplastic target for the primary action of boron deprivation, which signals deeper into the cell via endocytosis-mediated pectin signaling along putative cell wall-plasma membrane-cytoskeleton continuum.
Arabidopsis CYP98A3 Mediating Aromatic 3-Hydroxylation. Developmental Regulation of the Gene, and Expression in Yeast
Authors: Nair Ramesh B. , Xia Qun , Kartha Cyril J. , Kurylo Eugen , Hirji Rozina N. , Datla Raju , Selvaraj Gopalan 
Published: September 2002

Abstract
The general phenylpropanoid pathways generate a wide array of aromatic secondary metabolites that range from monolignols, which are ubiquitous in all plants, to sinapine, which is confined to crucifer seeds. The biosynthesis of these compounds involves hydroxylated and methoxylated cinnamyl acid, aldehyde, or alcohol intermediates. Of the three enzymes originally proposed to hydroxylate the 4-, 3-, and 5-positions of the aromatic ring, cinnamate 4-hydroxylase (C4H), which converts trans-cinnamic acid top-coumaric acid, is the best characterized and is also the archetypal plant P450 monooxygenase. Ferulic acid 5-hydroxylase (F5H), a P450 that catalyzes 5-hydroxylation, has also been studied, but the presumptive 3-hydroxylase converting p-coumarate to caffeate has been elusive. We have found that Arabidopsis CYP98A3, also a P450, could hydroxylate p-coumaric acid to caffeic acid in vivo when expressed in yeast (Saccharomyces cerevisiae) cells, albeit very slowly.CYP98A3 transcript was found in Arabidopsis stem and silique, resembling both C4H and F5Hin this respect. CYP98A3 showed further resemblance toC4H in being highly active in root, but differed fromF5H in this regard. In transgenic Arabidopsis, the promoters of CYP98A3 and C4H showed wound inducibility and a comparable developmental regulation throughout the life cycle, except in seeds, where the CYP98A3 promoter construct was inactive while remaining active in silique walls. Within stem and root tissue, the gene product and the promoter activity ofCYP98A3 were most abundant in lignifying cells. Collectively, these studies show involvement of CYP98A3 in the general phenylpropanoid metabolism, and suggest a downstream function for CYP98A3 relative to the broader and upstream role of C4H.