bluuebunny/crossref_metadata_2025 huggingface dataset:
Planets, life and the production of entropy
Authors: Lorenz Ralph D.
Published: July 2002

Two thermodynamic principles offer considerable insight into the climatic and geological settings for life on other planets, namely (1) that natural systems tend to actually achieve the ideal (‘Carnot’) limit of conversion of heat into work and (2) if a fluid system such as an atmosphere has sufficient degrees of freedom, it will choose the degree of heat transport that maximizes the generation of work (equivalently, that which offers maximum entropy production). The first principle agrees well with results on terrestrial cumulus convection, and the mechanical energy released by tectonic activity. The second principle agrees with the observed zonal climates of Earth, Mars and Titan, and shows promise for planetary interiors too; I discuss applications in the investigation of paleoclimates and habitability. I compare the work performed by planetary atmospheres and interiors on the terrestrial planets and thereby predict a weakly eroded landscape on Titan. The association of life with the production of entropy is also noted, and the possibility of evaluating planetary entropy production by telescopic observation is discussed.
Perceptions about the WTO trade institutions
Authors: JACKSON JOHN H.
Published: July 2002

This article, based on a lecture given at the inauguration ceremony for the
new Advisory Centre on WTO Law, describes the broader world trading landscape
into which this new Centre emerges. Taking into account the possible implications
of the events on September 11, this article provides a brief analysis of the current
trade policy climate, asserting the necessity of institutions for the successful
functioning of markets. After a short institutional history of the GATT/WTO, the
author describes the importance of institutional rules, treaty text, and practice for
the success of the WTO and presents the current debate over what the scope of this
institution has been, is now, and could be in the future – the debate over which
important issues should be taken under the WTO umbrella, and, further, which
issues are appropriate to send to the Dispute Settlement System. Finally, this article
illustrates the challenges facing this dispute settlement system, proposals for reform,
and the vital role that the new Advisory Centre may be able to play in resolving
some of these challenges.
A DNA replication-arrest site RTS1 regulates imprinting by determining the direction of replication at mat1 in S. pombe
Authors: Dalgaard Jacob Z. , Klar Amar J.S.
Published: July 2002

Mating-type switching in Schizosaccharomyces pombe involves a strand-specific, alkali-labile imprint at the mat1(mating-type) locus. The imprint is synthesized during replication in aswi1, swi3, and polymerase α (swi7) dependent manner and is dependent on mat1 being replicated in a specific direction. Here we show that the direction of replication atmat1 is controlled by a cis-acting polar terminator of replication (RTS1). Two-dimensional gel analysis of replication intermediates reveals that RTS1 only terminates replication forks moving in the centromere-distal direction. A genetic analysis shows that RTS1 optimizes the imprinting process. Transposing the RTS1 element to the distal side of mat1 abolishes imprinting of the native mat1 allele but restores imprinting of an otherwise unimprinted inverted mat1 allele. These data provide conclusive evidence for the “direction of replication model” that explains the asymmetrical switching pattern of S. pombe, and identify a DNA replication-arrest element implicated in a developmental process. Such elements could play a more general role during development and differentiation in higher eukaryotes by regulating the direction of DNA replication at key loci.
Inhibition of touch cell fate by egl-44 and egl-46 in C. elegans
Authors: Wu Ji , Duggan Anne , Chalfie Martin
Published: July 2002

In wild-type Caenorhabditis elegans, six cells develop as receptors for gentle touch. In egl-44 and egl-46mutants, two other neurons, the FLP cells, express touch receptor-like features. egl-44 and egl-46 also affect the differentiation of other neurons including the HSN neurons, two cells needed for egg laying. egl-44 encodes a member of the transcription enhancer factor family. The product of the egl-46gene, two Drosophila proteins, and two proteins in human and mice define a new family of zinc finger proteins. Both egl-44and egl-46 are expressed in FLP and HSN neurons (and other cells); expression of egl-46 is dependent on egl-44 in the FLP cells but not in the HSN cells. Wild-type touch cells expressegl-46 but not egl-44. Moreover, ectopic expression ofegl-44 in the touch cells prevents touch cell differentiation in an egl-46-dependent manner. The sequences of these genes and their nuclear location as seen with GFP fusions indicate that they repress transcription of touch cell characteristics in the FLP cells.
Nuclear translocation controlled by alternatively spliced isoforms inactivates the QUAKING apoptotic inducer
Authors: Pilotte Julie , Larocque Daniel , Richard Stéphane
Published: July 2002

The quaking viable mice have myelination defects and develop a characteristic tremor 10 d after birth. The quaking gene encodes at least five alternatively spliced QUAKING (QKI) isoforms that differ in their C-terminal 8–30-amino-acid sequence. The reason for the existence of the different QKI isoforms and their function are unknown. Here we show that only one QKI isoform, QKI-7, can induce apoptosis in fibroblasts and primary rat oligodendrocytes. Heterodimerization of the QKI isoforms results in the nuclear translocation of QKI-7 and the suppression of apoptosis. The unique C-terminal 14 amino acids of QKI-7 confers the ability to induce apoptosis to heterologous proteins such as the green fluorescent protein and a QKI-related protein, Caenorhabditis elegansGLD-1. Thus, the unique C-terminal sequences of QKI-7 may function as a life-or-death ‘sensor’ that monitors the balance between the alternatively spliced QKI isoforms. Moreover, our findings suggest that nuclear translocation is a novel mechanism of inactivating apoptotic inducers.
A conserved ubiquitin ligase of the nuclear envelope/endoplasmic reticulum that functions in both ER-associated and Matα2 repressor degradation
Authors: Swanson Robert , Locher Martin , Hochstrasser Mark
Published: July 2002

Substrate discrimination in the ubiquitin–proteasome system is believed to be dictated by specific combinations of ubiquitin–protein ligases (E3s) and ubiquitin-conjugating enzymes (E2s). Here we identify Doa10/Ssm4 as a yeast E3 that is embedded in the endoplasmic reticulum (ER)/nuclear envelope yet can target the soluble transcription factor Matα2. Doa10 contains an unusual RING finger, which has ubiquitin-ligase activity in vitro and is essential in vivo for degradation of α2 via its Deg1 degradation signal. Doa10 functions with two E2s, Ubc6 and Ubc7, to ubiquitinateDeg1-bearing substrates, and it is also required for the degradation of at least one ER membrane protein. Interestingly, different short-lived ER proteins show distinct requirements for Doa10 and another ER-localized E3, Hrd1. Nevertheless, the two E3s overlap in function: A doa10Δ hrd1Δ mutant is far more sensitive to cadmium relative to either single mutant and displays strong constitutive induction of the unfolded protein response; this suggests a role for both E3s in eliminating aberrant ER proteins. The likely human ortholog of DOA10 is in the cri-du-chat syndrome critical region on chromosome 5p, suggesting that defective ubiquitin ligation might contribute to this common genetic disorder.
Activation of Wnt signaling bypasses the requirement for RTK/Ras signaling during C. elegans vulval induction
Authors: Gleason Julie E. , Korswagen Hendrik C. , Eisenmann David M.
Published: July 2002

During Caenorhabditis elegans vulval development, activation of receptor tyrosine kinase/Ras and Notch signaling pathways causes three vulval precursor cells (VPCs) to adopt induced cell fates. A Wnt signaling pathway also acts in cell fate specification by the VPCs, via regulation of the Hox gene lin-39. We show here that either mutation of pry-1 or expression of an activated BAR-1 β-catenin protein causes an Overinduced phenotype, in which greater than three VPCs adopt induced cell fates. This indicates thatpry-1, which encodes a C. elegans axin homolog, acts as a negative regulator of Wnt signaling in the VPCs. Loss of activity of the APC homolog apr-1 increases the penetrance of this Overinduced phenotype, suggesting that APR-1 may play a negative role in Wnt signaling in this process in C. elegans similar to APC proteins in other systems. The Overinduced phenotype is suppressed by reduction of function of the genes pop-1 TCF and lin-39 Hox. Surprisingly, the Overinduced phenotype caused by hyperactivated Wnt signaling is not dependent on signaling through the Ras pathway. These data suggest that hyperactivation of Wnt signaling is sufficient to cause VPCs to adopt induced fates and that a canonical Wnt pathway may play an important role during C. elegans vulval induction.
Optical Mapping of BAC Clones from the Human Y Chromosome DAZ Locus
Authors: Giacalone Joseph , Delobette Stephanie , Gibaja Veronica , Ni Lei , Skiadas Yiannis , Qi Rong , Edington Joanne , Lai Zhongwu , Gebauer Damara , Zhao Hongjuan , Anantharaman Thomas , Mishra Bhubaneswar , Brown Laura G. , Saxena Richa , Page David C. , Schwartz David C.
Published: July 2002

The accurate mapping of clones derived from genomic regions containing complex arrangements of repeated elements presents special problems for DNA sequencers. Recent advances in the automation of optical mapping have enabled us to map a set of 16 BAC clones derived from the DAZ locus of the human Y chromosome long arm, a locus in which the entire DAZ gene as well as subsections within the gene copies have been duplicated. High-resolution optical mapping employing seven enzymes places these clones into two contigs representing four distinct copies of the DAZ gene and highlights a number of differences between individual copies of DAZ.
Structure and Evolution of the Smith-Magenis Syndrome Repeat Gene Clusters, SMS-REPs
Authors: Park Sung-Sup , Stankiewicz Paweł , Bi Weimin , Shaw Christine , Lehoczky Jessica , Dewar Ken , Birren Bruce , Lupski James R.
Published: July 2002

An ∼4-Mb genomic segment on chromosome 17p11.2, commonly deleted in patients with the Smith-Magenis syndrome (SMS) and duplicated in patients with dup(17)(p11.2p11.2) syndrome, is flanked by large, complex low-copy repeats (LCRs), termed proximal and distal SMS-REP. A third copy, the middle SMS-REP, is located between them. SMS-REPs are believed to mediate nonallelic homologous recombination, resulting in both SMS deletions and reciprocal duplications. To delineate the genomic structure and evolutionary origin of SMS-REPs, we constructed a bacterial artificial chromosome/P1 artifical chromosome contig spanning the entire SMS region, including the SMS-REPs, determined its genomic sequence, and used fluorescence in situ hybridization to study the evolution of SMS-REP in several primate species. Our analysis shows that both the proximal SMS-REP (∼256 kb) and the distal copy (∼176 kb) are located in the same orientation and derived from a progenitor copy, whereas the middle SMS-REP (∼241 kb) is inverted and appears to have been derived from the proximal copy. The SMS-REP LCRs are highly homologous (>98%) and contain at least 14 genes/pseudogenes each. SMS-REPs are not present in mice and were duplicated after the divergence of New World monkeys from pre-monkeys ∼40–65 million years ago. Our findings potentially explain why the vast majority of SMS deletions and dup(17)(p11.2p11.2) occur at proximal and distal SMS-REPs and further support previous observations that higher-order genomic architecture involving LCRs arose recently during primate speciation and may predispose the human genome to both meiotic and mitotic rearrangements.
Impairment of Spatial Learning and Hippocampal Synaptic Potentiation in c-kit Mutant Rats
Authors: Katafuchi Toshihiko , Li Ai-Jun , Hirota Seiichi , Kitamura Yukihiko , Hori Tetsuro
Published: July 2002

The c-kit receptor tyrosine kinase encoded by the white-spotting (W) gene is highly expressed in rat hippocampal CA1–CA4 regions. We found an impaired spatial learning and memory in homozygous c-kit (Ws/Ws) mutant rats that have a 12-base deletion in the tyrosine kinase domain of thec-kit gene and a very low kinase activity. Electrophysiological studies in hippocampal slices revealed that the long-term potentiation (LTP) induced by the tetanic stimulation (100 Hz, 1 sec) in the mossy fiber (MF)–CA3 pathway, but not in the Schaffer collaterals/commissural–CA1 pathway, was significantly reduced in c-kit mutants compared with wild-type (+/+) rats. The paired-pulse facilitation (PPF) was measured before the tetanus and after the establishment of the LTP in each slice. The initial PPF in the MF–CA3 pathway positively correlated with the amplitude of the LTP in the wild-type rats but not in the c-kit mutant rats. Furthermore, they failed to show the normal characteristics observed in the MF–CA3 pathway of +/+ rats; that is, the negative correlation between the initial PPF and the changes in PPF measured after the LTP. These findings suggest an involvement of SCF/c-kit signaling in hippocampal synaptic potentiation and spatial learning and memory.
Dissociation Between the Effects of Damage to Perirhinal Cortex and Area TE
Authors: Buffalo Elizabeth A. , Ramus Seth J. , Clark Robert E. , Teng Edmond , Squire Larry R. , Zola Stuart M.
Published: July 2002

Perirhinal cortex and area TE are immediately adjacent to each other in the temporal lobe and reciprocally interconnected. These areas are thought to lie at the interface between visual perception and visual memory, but it has been unclear what their separate contributions might be. In three experiments, monkeys with bilateral lesions of the perirhinal cortex exhibited a different pattern of impairment than monkeys with bilateral lesions of area TE. In experiment 1, lesions of the perirhinal cortex produced a multimodal deficit in recognition memory (delayed nonmatching to sample), whereas lesions of area TE impaired performance only in the visual modality. In experiment 2, on a test of visual recognition memory (the visual paired comparison task) lesions of the perirhinal cortex impaired performance at long delays but spared performance at a very short delay. In contrast, lesions of area TE impaired performance even at the short delay. In experiment 3, lesions of the perirhinal cortex and lesions of area TE produced an opposite pattern of impairment on two visual discrimination tasks, simple object discrimination learning (impaired only by perirhinal lesions), and concurrent discrimination learning (impaired only by TE lesions). Taken together, the findings suggest that the perirhinal cortex, like other medial temporal lobe structures, is important for the formation of memory, whereas area TE is important for visual perceptual processing.
Oxidative Stress Increased Respiration and Generation of Reactive Oxygen Species, Resulting in ATP Depletion, Opening of Mitochondrial Permeability Transition, and Programmed Cell Death
Authors: Tiwari Budhi Sagar , Belenghi Beatrice , Levine Alex
Published: July 2002

Mitochondria constitute a major source of reactive oxygen species and have been proposed to integrate the cellular responses to stress. In animals, it was shown that mitochondria can trigger apoptosis from diverse stimuli through the opening of MTP, which allows the release of the apoptosis-inducing factor and translocation of cytochrome c into the cytosol. Here, we analyzed the role of the mitochondria in the generation of oxidative burst and induction of programmed cell death in response to brief or continuous oxidative stress in Arabidopsis cells. Oxidative stress increased mitochondrial electron transport, resulting in amplification of H2O2 production, depletion of ATP, and cell death. The increased generation of H2O2 also caused the opening of the MTP and the release of cytochromec from mitochondria. The release of cytochromec and cell death were prevented by a serine/cysteine protease inhibitor, Pefablock. However, addition of inhibitor only partially inhibited the H2O2 amplification and the MTP opening, suggesting that protease activation is a necessary step in the cell death pathway after mitochondrial damage.
Purification and Properties of Arabidopsis thaliana COR (Cold-Regulated) Gene Polypeptides COR15am and COR6.6 Expressed in Escherichia coli
Authors: Glimour S. J. , Lin C. , Thomashow M. F.
Published: July 2002

Arabidopsis thaliana cold-regulated genes COR15a and COR6.6 encode 15- and 6.6-kD polypeptides, respectively. The COR15a polypeptide is known to be targeted to chloroplasts and, during import, to be processed to a 9.4-kD polypeptide designated COR15am. The COR6.6 polypeptide is thought to be located in the cytosol. The coding sequences for COR15am and COR6.6 were fused to the bacteriophage T7 promoter and expressed in Escherichia coli. The recombinant polypeptides COR15amr and COR6.6r were purified to near homogeneity using a combination of ammonium sulfate fractionation, ion-exchange chromatography, and adsorption chromatography on hydroxyapatite. COR15amr and the major species of COR15am in chloroplasts co-migrated on both two-dimensional O'Farrell gels and nondenaturing polyacrylamide gels. These data corroborate the site of COR15a processing and indicate no difference in charge or quaternary structure between COR15amr and the major species of COR15am in plants. In contrast, the migration patterns of COR6.6r and COR6.6 on two-dimensional gels suggest that a considerable portion of the COR6.6 population in plants is modified. In the accompanying papers (M.S. Webb, S.J. Gilmour, M.F. Thomashow, P.L. Steponkus [1996] Plant Physiology 111: 301–312; M. Uemura, S.J. Gilmour, M.F. Thomashow, P.L. Steponkus [1996] Plant Physiology 111:313–327), the effects of COR15amr and COR6.6r on the cryostability and lyotropic phase behavior of liposomes are examined.
Proteolytic Processing of Class IV Chitinase in the Compatible Interaction of Bean Roots with Fusarium solani
Authors: Lange J. , Mohr U. , Wiemken A. , Boller T. , Vogeli-Lange R.
Published: July 2002

Three chitinase isoenzymes, PvChiE, PvChiF, and PvChiG (molecular masses 29, 28, and 27 kD, respectively), were purified from bean (Phaseolus vulgaris L. cv Saxa) roots infected with the fungal pathogen Fusarium solani f. sp. phaseoli, and their amino acid sequence was partially determined. All sequences from all three isoenzymes exactly matched deduced amino acid sequences of the bean class IV chitinase PvChi4, formerly called PR4. The N terminus of PvChiF mapped to the hinge region, and the N terminus of PvChiG mapped to the catalytic domain of PvChi4. The N terminus of PvChiE was blocked. The appearance of PvChiE, PvChiF, and PvChiG correlated with an increase in protease activity in infected roots, and they could be generated in vitro by mixing extracts with high protease activity with extracts containing high amounts of PvChi4. Extracts from infected roots prepared in the presence of protease inhibitors also contained the processed forms of PvChi4, indicating that processing occurred in planta and not as an artifact of extraction. Processing of PvChi4 was not detected in incompatible interactions with a nonhost strain of F. solani and in symbiotic interactions with Glomus mosseae, and thus may be important only in compatible interactions with F. solani.
Both 5[prime] and 3[prime] Sequences of Maize adh1 mRNA Are Required for Enhanced Translation under Low-Oxygen Conditions
Authors: Bailey-Serres J. , Dawe R. K.
Published: July 2002

Alcohol dehydrogenase-1 (ADH1) synthesis in O2-deprived roots of maize (Zea mays L.) results from induced transcription and selective translation of ADH1 mRNA. The effect of ADH1 mRNA sequences on message stability and translation was studied in protoplasts of the maize cell line P3377. 5[prime] capped and 3[prime] polyadenylated mRNA constructs containing the firefly gene (luc) for luciferase (LUC) or the Escherichia coli gene (uidA) for β-glucuronidase (GUS) coding region were synthesized in vitro and electroporated into protoplasts that were cultured at 40 or 5% O2. A LUC mRNA with a 17-nucleotide polylinker 5[prime] untranslated region (UTR) was expressed 10-fold higher under aerobic conditions than under hypoxic conditions. Expression of five chimeric ADH1-GUS mRNAs was measured relative to this LUC mRNA. An mRNA containing the 5[prime]-UTR and the first 18 codons of adh1 in a translational fusion with the GUS coding region and followed by the 3[prime]-UTR of adh1 was expressed 57-fold higher at 5% O2. Progressive deletion of adh1 5[prime]-UTR and coding sequences reduced expression of the GUS-mRNA at 5% O2, but had little impact on expression of 40% O2. Enhancement of expression in hypoxic protoplasts conferred by the adh1 5[prime]-UTR and the first 26 codons decreased more than 3-fold when the adh1 3[prime]-UTR was removed. In addition, the adh1 3[prime]-UTR slightly inhibited expression in aerobic protoplasts. The physical half-lives of the GUS and LUC mRNAs were similar under both anaerobic and hypoxic conditions, indicating that expression levels were largely independent of mRNA stability. Thus, both adh1 5[prime] and 3[prime] mRNA sequences are required for enhanced translation in protoplasts under O2 deprivation.
Immunolocalization of Mannitol Dehydrogenase in Celery Plants and Cells
Authors: Zamski E. , Yamamoto Y. T. , Williamson J. D. , Conkling M. A. , Pharr D. M.
Published: July 2002

Immunolocalization of mannitol dehydrogenase (MTD) in celery (Apium graveolens L.) suspension cells and plants showed that MTD is a cytoplasmic enzyme. MTD was found in the meristems of celery root apices, in young expanding leaves, in the vascular cambium, and in the phloem, including sieve-element/companion cell complexes, parenchyma, and in the exuding phloem sap of cut petioles. Suspension cells that were grown in medium with mannitol as the sole carbon source showed a high anti-MTD cross-reaction in the cytoplasm, whereas cells that were grown in sucrose-containing medium showed little or no cross-reaction. Gel-blot analysis of proteins from vascular and nonvascular tissues of mature celery petioles showed a strong anti-MTD sera cross-reactive band, corresponding to the 40-kD molecular mass of MTD in vascular extracts, but no cross-reactive bands in nonvascular extracts. The distribution pattern of MTD within celery plants and in cell cultures that were grown on different carbon sources is consistent w ith the hypothesis that the Mtd gene may be regulated by sugar repression. Additionally, a developmental component may regulate the distribution of MTD within celery plants.
Cloning and Subcellular Location of an Arabidopsis Receptor-Like Protein That Shares Common Features with Protein-Sorting Receptors of Eukaryotic Cells
Authors: Ahmed S. U. , Bar-Peled M. , Raikhel N. V.
Published: July 2002

Many receptors involved in clathrin-mediated protein transport through the endocytic and secretory pathways of yeast and animal cells share common features. They are all type I integral membrane proteins containing cysteine-rich lumenal domains and cytoplasmic tails with tyrosine-containing sorting signals. The cysteine-rich domains are thought to be involved in ligand binding, whereas the cytoplasmic tyrosine motifs interact with clathrin-associated adaptor proteins during protein sorting along these pathways. In addition, tyrosine-containing signals are required for the retention and recycling of some of these membrane proteins to the trans-Golgi network. Here we report the characterization of an approximately 80-kD epidermal growth factor receptor-like type I integral membrane protein containing all of these functional motifs from Arabidopsis thaliana (called AtELP for A. thaliana Epidermal growth factor receptor-Like Protein). Biochemical analysis indicates that AtELP is a membrane protein found at high levels in the roots of both monocots and dicots. Subcellular fractionation studies indicate that the AtELP protein is present in two membrane fractions corresponding to a novel, undefined compartment and a fraction enriched in vesicles containing clathrin and its associated adaptor proteins. AtELP may therefore serve as a marker for compartments involved in intracellular protein trafficking in the plant cell.
Subcellular Localization of Celery Mannitol Dehydrogenase (A Cytosolic Metabolic Enzyme in Nuclei)
Authors: Yamamoto Y. T. , Zamski E. , Williamson J. D. , Conkling M. A. , Pharr D. M.
Published: July 2002

Mannitol dehydrogenase (MTD) is the first enzyme in mannitol catabolism in celery (Apium graveolens L. var dulce [Mill] Pers. Cv Florida 638). Mannitol is an important photoassimilate, as well as providing plants with resistance to salt and osmotic stress. Previous work has shown that expression of the celery Mtd gene is regulated by many factors, such as hexose sugars, salt and osmotic stress, and salicylic acid. Furthermore, MTD is present in cells of sink organs, phloem cells, and mannitol-grown suspension cultures. Immunogold localization and biochemical analyses presented here demonstrate that celery MTD is localized in the cytosol and nuclei. Although the cellular density of MTD varies among different cell types, densities of nuclear and cytosolic MTD in a given cell are approximately equal. Biochemical analyses of nuclear extracts from mannitol-grown cultured cells confirmed that the nuclear-localized MTD is enzymatically active. The function(s) of nuclear-localized MTD is unknown.
Drying Increases Intracellular Partitioning of Amphiphilic Substances into the Lipid Phase
Authors: Golovina Elena A. , Hoekstra Folkert A. , Hemminga Marcus A.
Published: July 2002

Previously we proposed that endogenous amphiphilic substances may partition from the aqueous cytoplasm into the lipid phase during dehydration of desiccation-tolerant organ(ism)s and vice versa during rehydration. Their perturbing presence in membranes could thus explain the transient leakage from imbibing organisms. To study the mechanism of this phenomenon, amphiphilic nitroxide spin probes were introduced into the pollen of a model organism, Typha latifolia, and their partitioning behavior during dehydration and rehydration was analyzed by electron paramagnetic resonance spectroscopy. In hydrated pollen the spin probes mainly occurred in the aqueous phase; during dehydration, however, the amphiphilic spin probes partitioned into the lipid phase and had disappeared from the aqueous phase below 0.4 g water g−1 dry weight. During rehydration the probes reappeared in the aqueous phase above 0.4 g water g−1 dry weight. The partitioning back into the cytoplasm coincided with the decrease of the initially high plasma membrane permeability. A charged polar spin probe was trapped in the cytoplasm during drying. Liposome experiments showed that partitioning of an amphiphilic spin probe into the bilayer during dehydration caused transient leakage during rehydration. This was also observed with endogenous amphipaths that were extracted from pollen, implying similar partitioning behavior. In view of the fluidizing effect on membranes and the antioxidant properties of many endogenous amphipaths, we suggest that partitioning with drying may be pivotal to desiccation tolerance, despite the risk of imbibitional leakage.
Molecular Analysis of (R)-(+)-Mandelonitrile Lyase Microheterogeneity in Black Cherry1
Authors: Hu Zihua , Poulton Jonathan E.
Published: July 2002

The flavoprotein (R)-(+)-mandelonitrile lyase (MDL; EC 4.1.2.10), which plays a key role in cyanogenesis in rosaceous stone fruits, occurs in black cherry (Prunus serotina Ehrh.) homogenates as several closely related isoforms. Biochemical and molecular biological methods were used to investigate MDL microheterogeneity and function in this species. Three novel MDL cDNAs of high sequence identity (designated MDL2, MDL4, and MDL5) were isolated. Like MDL1 and MDL3 cDNAs (Z. Hu, J.E. Poulton [1997] Plant Physiol 115: 1359–1369), they had open reading frames that predicted a flavin adenine dinucleotide-binding site, multipleN-glycosylation sites, and an N-terminal signal sequence. The N terminus of an MDL isoform purified from seedlings matched the derived amino acid sequence of the MDL4 cDNA. Genomic sequences corresponding to the MDL1, MDL2, and MDL4 cDNAs were obtained by polymerase chain reaction amplification of genomic DNA. Like the previously reported mdl3 gene, these genes are interrupted at identical positions by three short, conserved introns. Given their overall similarity, we conclude that the genesmdl1, mdl2, mdl3,mdl4, and mdl5 are derived from a common ancestral gene and constitute members of a gene family. Genomic Southern-blot analysis showed that this family has approximately eight members. Northern-blot analysis using gene-specific probes revealed differential expression of the genes mdl1,mdl2, mdl3, mdl4, andmdl5.
Regions of the Pea Lhcb1*4 Promoter Necessary for Blue-Light Regulation in Transgenic Arabidopsis1
Authors: Folta Kevin M. , Kaufman Lon S.
Published: July 2002

Pea (Pisum sativum) and Arabidopsis contain similar, if not identical, blue-light (BL)-responsive systems that alter expression of specific members of the Lhcb (light-harvestingchlorophyll-binding) gene family. In both plants a single, short pulse of low-fluence BL (threshold = 10−1 μmol m−2) causes an increase in the rate of transcription from specific members of the Lhcbgene family in etiolated seedlings. Constructs of the BL-regulated peaLhcb1*4 promoter (PsLhcb1*4) were created, which altered sequences previously implicated in light responses, deleted the 5′-promoter sequence, or removed the 5′-untranslated region. These constructs were tested for BL induction in transgenic Arabidopsis. The PsLhcb1*4 promoter deletions to −150 bp maintained normal fluence response, time course, and reciprocity characteristics. The 5′- untranslated region contained enhancer elements, but was not necessary for BL induction. The −95 to +2 promoter was capable of responding to BL, whereas sequences from −50 were not. Promoters that lack conserved light-regulatory elements or sequences directly implicated in phytochrome and circadian responses retained BL activity, suggesting that the low-fluence BL response utilizes regions of the promoter independent of those that modulate the phytochrome and circadian responses.
Early Events in the Signal Pathway for the Oxidative Burst in Soybean Cells Exposed to Avirulent Pseudomonas syringaepv glycinea1
Authors: Rajasekhar Vinagolu K. , Lamb Chris , Dixon Richard A.
Published: July 2002

Soybean (Glycine max) cv Williams 82 suspension cultures exhibit an oxidative burst approximately 3 h after challenge withPseudomonas syringae pv glycinea(Psg) harboring the avrA (avirulence) gene. Pretreatment with the tyrosine (Tyr) kinase inhibitor herbimycin A or the serine/threonine kinase inhibitor K252a abolished the burst and subsequent induction of glutathioneS-transferase. However, imposition of a 45-min rest period between pathogen challenge and subsequent addition of the kinase inhibitors resulted in escape from inhibition by herbimycin A, whereas inhibition by K252a persisted. Suramin, a G-protein inhibitor, inhibited the burst if added up to 90 min after pathogen challenge. The burst was also induced by the ion channel generator amphotericin B, and this induction was sensitive to suramin and K252a. Conversely, the ion channel blocker anthracene-9-carboxylate inhibited thePsg:avrA-induced burst.Psg:avrA rapidly induced Tyr phosphorylation of several proteins, and this was inhibited by herbimycin A or anthracene 9-carboxylic acid. These data suggest that the activation of ion channels is followed by an upstream Tyr kinase before the serine/threonine kinase-dependent steps in the signal pathway leading to the oxidative burst.Psg:avrA-dependent induction of phenylalanine ammonia-lyase was not inhibited by herbimycin or suramin, suggesting the operation of different signal pathways for the oxidative burst and phenylpropanoid-derived defense responses.
Conservation of Matrix Attachment Region-Binding Filament-Like Protein 1 among Higher Plants
Authors: Harder Patricia A. , Silverstein Rebecca A. , Meier Iris
Published: July 2002

The interaction of chromatin with the nuclear matrix via matrix attachment regions (MARs) on the DNA is considered to be of fundamental importance for higher-order chromatin organization and the regulation of gene expression. We have previously isolated a novel nuclear matrix-localized protein (MFP1) from tomato (Lycopersicon esculentum) that preferentially binds to MAR DNA. Tomato MFP1 has a predicted filament-protein-like structure and is associated with the nuclear envelope via an N-terminal targeting domain. Based on the antigenic relationship, we report here that MFP1 is conserved in a large number of dicot and monocot species. Several cDNAs were cloned from tobacco (Nicotiana tabacum) and shown to correspond to two tobacco MFP1 genes. Comparison of the primary and predicted secondary structures of MFP1 from tomato, tobacco, and Arabidopsis indicates a high degree of conservation of the N-terminal targeting domain, the overall putative coiled-coil structure of the protein, and the C-terminal DNA-binding domain. In addition, we show that tobacco MFP1 is regulated in an organ-specific and developmental fashion, and that this regulation occurs at the level of transcription or RNA stability.
The Effects of Elevated CO2 Concentrations on Cell Division Rates, Growth Patterns, and Blade Anatomy in Young Wheat Plants Are Modulated by Factors Related to Leaf Position, Vernalization, and Genotype
Authors: Masle Josette
Published: July 2002

This study demonstrates that elevated [CO2] has profound effects on cell division and expansion in developing wheat (Triticum aestivum L.) leaves and on the quantitative integration of these processes in whole-leaf growth kinetics, anatomy, and carbon content. The expression of these effects, however, is modified by intrinsic factors related to genetic makeup and leaf position, and also by exposure to low vernalizing temperatures at germination. Beyond these interactions, leaf developmental responses to elevated [CO2] in wheat share several remarkable features that were conserved across all leaves examined. Most significantly: (a) the contribution of [CO2] effects on meristem size and activity in driving differences in whole-blade growth kinetics and final dimensions; (b) an anisotropy in cellular growth responses to elevated [CO2], with final cell length and expansion in the paradermal plane being highly conserved, even when the rates and duration of cell elongation were modified, while cell cross-sectional areas were increased; (c) tissue-specific effects of elevated [CO2], with significant modifications of mesophyll anatomy, including an increased extension of intercellular air spaces and the formation of, on average, one extra cell layer, while epidermal anatomy was mostly unaltered. Our results indicate complex developmental regulations of sugar effects in expanding leaves that are subjected to genetic variation and influenced by environmental cues important in the promotion of floral initiation. They also provide insights into apparently contradictory and inconsistent conclusions of published CO2 enrichment studies in wheat.
Covalent Binding of the Benzamide RH-4032 to Tubulin in Suspension-Cultured Tobacco Cells and Its Application in a Cell-Based Competitive-Binding Assay
Authors: Young David H. , Lewandowski Veronica T.
Published: July 2002

The benzamide, RH-4032, was found to be a potent antimicrotubule agent in tobacco (Nicotiana tabacum) cells. It strongly inhibited root growth and produced swollen club-shaped roots, an accumulation of cells in arrested metaphase, and loss of microtubules. RH-4032 inhibited the in vitro assembly of bovine tubulin into microtubules, with inhibition requiring a relatively long incubation period. Treatment of tobacco suspension-cultured cells or isolated bovine tubulin with [14C]RH-4032, and analysis of radiolabeled protein revealed a highly specific covalent attachment to β-tubulin. Binding of [3H]RH-4032 in tobacco suspension-cultured cells was shown to be saturable and to be influenced by pre-incubation of the cells with various antimicrotubule agents: Binding of [3H]RH-4032 was inhibited by the benzamides, pronamide and zarilamide, theN-phenylcarbamate, chlorpropham, and the microtubule-stabilizing drug, paclitaxel, whereas trifluralin and amiprophosmethyl were not inhibitory. A common characteristic of agents that cause microtubule disassembly was a slight enhancement of [3H]RH-4032 binding at low concentrations, which did not occur with the microtubule-stabilizing agent paclitaxel. For structural analogs of RH-4032 and various N-phenylcarbamates, it was shown that the ability to inhibit binding of [3H]RH-4032 was correlated with the ability to inhibit tobacco root elongation. The results suggest a common binding site on β-tubulin for RH-4032, pronamide, zarilamide, and chlorpropham, which is distinct from the binding site(s) for trifluralin and amiprophosmethyl. RH-4032 provides a unique approach to studying effects of antimicrotubule agents on plant cells by allowing competitive tubulin binding assays to be conducted in whole cells.
An Increase in Pectin Methyl Esterase Activity Accompanies Dormancy Breakage and Germination of Yellow Cedar Seeds
Authors: Ren Chengwei , Kermode Allison R.
Published: July 2002

Pectin methyl esterase (PME) (EC 3.1.1.11) catalyzes the hydrolysis of methylester groups of cell wall pectins. We investigated the role of this enzyme in dormancy termination and germination of yellow cedar (Chamaecyparis nootkatensis [D. Don] Spach) seeds. PME activity was not detected in dormant seeds of yellow cedar but was induced and gradually increased during moist chilling; high activity coincided with dormancy breakage and germination. PME activity was positively correlated to the degree of dormancy breakage of yellow cedar seeds. The enzyme produced in different seed parts and in seeds at different times during moist chilling, germination, and early post-germinative growth consisted of two isoforms, both basic with isoelectric points of 8.7 and 8.9 and the same molecular mass of 62 kD. The pH optimum for the enzyme was between 7.4 and 8.4. In intact yellow cedar seeds, activities of the two basic isoforms of PME that were induced in embryos and in megagametophytes following dormancy breakage were significantly suppressed by abscisic acid. Gibberellic acid had a stimulatory effect on the activities of these isoforms in embryos and megagametophytes of intact seeds at the germinative stage. We hypothesize that PME plays a role in weakening of the megagametophyte, allowing radicle emergence and the completion of germination.
Tuber Physiology and Properties of Starch from Tubers of Transgenic Potato Plants with Altered Plastidic Adenylate Transporter Activity
Authors: Geigenberger Peter , Stamme Claudia , Tjaden Joachim , Schulz Alexander , Quick Paul W. , Betsche Thomas , Kersting H. J. , Neuhaus H. Ekkehard
Published: July 2002

We showed recently that antisense plants with decreased activity of the plastidic ATP/ADP-transporter protein exhibit drastically reduced levels of starch and a decreased amylose/amylopectin ratio, whereas sense plants with increased activity of the transporter possessed more starch than wild-type plants and an increased amylose/amylopectin ratio. In this paper we investigate the effect of altered plastidic ATP/ADP-transporter protein expression on primary metabolism and granule morphology in more detail. Tuber tissues from antisense and sense plants exhibited substantially increased respiratory activity compared with the wild type. Tubers from antisense plants contained markedly increased levels of free sugars, UDP-Glc, and hexose phosphates, whereas phosphoenolpyruvate, isocitrate, ATP, ADP, AMP, UTP, UDP, and inorganic pyrophosphate levels were slightly decreased. In contrast, tubers from sense plants revealed a slight increase in adenine and uridine nucleotides and in the levels of inorganic pyrophosphate, whereas no significant changes in the levels of soluble sugars and metabolites were observed. Antisense tubers contained 50% reduced levels of ADP-Glc, whereas sense tubers contained up to 2-fold increased levels of this sole precursor for starch biosynthesis. Microscopic examination of starch grain morphology revealed that the size of starch grains from antisense tubers was substantially smaller (50%) compared with the wild type. The large starch grains from sense tubers appeared of a more angular morphology, which differed to the more ellipsoid shape of wild type grains. The results suggest a close interaction between plastidial adenylate transport and starch biosynthesis, indicating that ADP-Glc pyrophosphorylase is ATP-limited in vivo and that changes in ADP-Glc concentration determine starch yield, as well as granule morphology. Possible factors linking starch synthesis and respiration are discussed.
Aerospace composites
Authors: Ford Terry
Published: July 2002

Details the development of composites, in particular carbon fibre reinforced plastics, for use in aerospace structures. Describes a wide range of products manufactured by various companies. Looks at the integrity of these materials and the testing methods used to ensure this. In particular, discusses metal matrix composites, aluminium/silicon carbide particulate MMCs and fibre‐metal laminates. Finally looks at advanced composites’ promise of being able to meet the needs of high specific properties and enhanced temperature capability required for future engines.
Food retailers’ responses to the GM controversy within the UK
Authors: Jones Peter , Clarke‐Hill Colin , Hillier David , Shears Peter
Published: July 2002

During the late 1990s the controversy surrounding the use of genetically modified ingredients in food became an increasingly controversial issue within the UK. This paper provides a short case study which focuses on the principal issues within the GM debate and reviews the major food retailers policy responses to this debate.
Extending the group: a strategy for virtual team formation
Authors: Joy‐Matthews Jennifer , Gladstone Bryan
Published: July 2002

Discusses the emergence of virtual teams in the current business world. The issues posed by virtuality as opposed to proximity for group members and trainers and developers are raised. The stages of group processes – from formation/socialisation to the adjournment of virtual teams – are identified and considered in relation to virtuality and proximity. Examples are given from the Electronic Communication Forum (ECF) showing how the reality of working practices mirrors the theory offered. Some questions are posed which will need further research before answers can be generated.
Practitioners as educators: the Bristol MSc in Information and Library Management
Authors: Heery Mike
Published: July 2002

The background leading up to the estblishment of a library and information (LIS) school by a consortium of university libraries in the Bristol area is described. Course development and structure are examined. Practical consequences of the course and issues arising from the school’s establishment and operation are discussed within a broader professional context. These include the use of practitioners as lecturers and implications for research; and developments in the professional curriculum including the place of generic skills and specialisms.
Are fruit tuck shops in primary schools effective in increasing pupils’ fruit consumption? A randomised controlled trial
Authors: Moore Laurence , Paisley Claire M. , Dennehy Anne
Published: July 2002

Describes a two‐year project funded by the Ministry of Agriculture, Fisheries and Food, which commenced in October 1998. The aim of the project is to test whether the introduction of fruit tuck shops in primary schools in underprivileged areas can be associated with a change in the fruit consumption of pupils at those schools, when compared with pupils in comparison schools where fruit tuck shops are not in operation. A secondary aim is to identify the most effective ways of operating fruit tuck shops in primary schools. Overall, the research will provide guidance to schools, health and education authorities on the feasibility and potential nutritional benefit of setting up fruit tuck shops in primary schools.
Characterization and modelling of piston ring‐cylinder tribosystem microtopography in lubricated contact
Authors: Pandazaras C.N. , Petropoulos G.P.
Published: July 2002

A study of piston ring‐cylinder tribological behaviour under mixed lubrication mode is usually based upon data regarding surface contact magnitudes, fluid film characteristics and resultant mixed friction forces. The present paper introduces a Fisher‐Pearson statistical model to describe elastic deformation of piston rings and liners’ asperities in order to derive more realistic functions that represent the aforementioned functional quantities considering real surfaces of used and worn liners. The hypothesis that the microtopography follows Gaussian law overestimates critical contact magnitudes such as: minimum film thickness‐surface separation distance, deformed asperities supported load, number of contacts and contact area. Increased time of use and wear of liners decreases transverse geometrical anisotropy. Correction contact integral functions in cases of used liners’ surfaces may be calculated through surface profile measurements. Theoretical and experimental results are in good agreement for the configuration considered.
Slick 50 – a proven PTFE‐based boundary lubricant for engines
Authors: Wilson Bill
Published: July 2002

Describes the testing and lubricating mechanisms of Slick 50, a solid lubricant engine oil additive containing PTFE for reducing friction and wear. Gives the results of long term engine tests by the Southwest Research Institute, Texas, monitored by radioactive tracer, exhaust emission analysis and fuel economy improvement. Offers Slick 50 as an alternative to zinc phosphorus additives.
The implications of new technology for the skill and training needs of small‐ and medium‐sized printing firms
Authors: Smallbone David , Supri Salinder , Baldock Robert
Published: July 2002

Investigates the implications of digital technology for the skill and training needs of small printing firms. The picture that emerges is one where the emphasis is on re‐training due to technological change. The bulk of this training takes place in the workplace, with initial training typically being supplied by an equipment or software supplier as part of the initial purchase package. The skills gained by the key workers selected for initial training are then passed on informally to other staff in the firm. There is rarely a high level of commitment or a systematic approach to training that might be expected given the scale of the investment costs that many of these firms have incurred. Only a few proactively‐managed small‐ to medium‐sized enterprises are recognising the need to constantly update their workforce skills.
Striving for seamlessness
Authors: Cohen Claire
Published: July 2002

Describes the writer′s experiences as “author” of a
procedures manual for a large contract cleaning company. The senior
managers were anxious to take control over what they saw as an unwieldy
organization with unclear procedures that badly needed streamlining. The
manual reflected senior managers′ need to set up an illusion of control
over the organization; in its production process and in its style, it
suggested both that a coolly analytical, rational and logical approach
was being taken to organizational description and rationalization, and
that it was morally right to follow the procedures described. Yet in
fulfilling senior managers′ requirements, the manual did not reflect the
mess of organizational procedures, and its smooth,
“seamless” descriptions implied that employees had nothing
original to add to organizational procedures. Concludes that procedures
manuals might be seen as inimical to individuality, as a force for
control by senior management, and as a means of inhibiting employee
creativity.