bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vigilance and neighbour distance in foraging flocks of red‐billed choughs, Pyrrhocorax pyrrhocorax
Authors: Rolando Antonio , Caldoni Riccardo , De Sanctis Augusto , Laiolo Paola 
Published: July 2002

AbstractForaging flocks of red‐billed choughs (Pyrrhocorax pyrrhocorax) were studied in the Gran Sasso National Park (Apennines, Central Italy) to assess the relevance of neighbour distance and group size upon vigilance, after controlling for other confounding variables (feeding frequency, air temperature and time of the day). Both partial correlation and multiple regression analyses clearly suggested that neighbour distance was the major determinant of the vigilant behaviour in the red‐billed chough, even though group size would also exert a certain influence. As no significant correlation between the two variables was found, it can be assumed that the relationship between vigilance and neighbour distance is not spurious. Feeding frequencies were not significantly correlated with the other variables, except for temperature, for which a positive correlation was observed. Since the red‐billed chough usually feeds on insects, which become more active and available as temperature increases, we suggest that the feeding frequency of the red‐billed chough mostly depends on food availability. Our results are discussed in the framework of the hypotheses put forward to explain vigilance behaviour. The conclusion is that the ‘individual risk hypothesis’ explains the behaviour of the red‐billed chough better than the ‘many eyes hypothesis’.
Aging and agism in the 21st century
Authors: Tadd Win 
Published: July 2002

EditorialWhilst preparing this editorial, I was struck by the ambivalent attitudes displayed towards older people in Western society. In London, for example, the crowds thronging the Mall and cheering the Queen Mother for reaching her centenary belied the fact that society generally treats its older members with disdain. That is, until they reach 100 years and then everyone wants to know the secret of their success.
The Asymptotic Proportion of Subdivisions of a 2 × 2
Table that Result in Simpson's Paradox
Authors: HADJICOSTAS PETROS 
Published: July 2002

In [1], recently published in Combinatorics, Probability and
Computing, there was a typographical error. On p. 392, part (5) of Lemma 3.1,
the formula should read as follows:formula hereReferences[1] Hadjicostas, P. (1998) The asymptotic proportion of subdivisions of a
2 × 2 table that result in Simpson's Paradox. Combinatorics, Probability
and Computing7 387–396.
Competition between Barclays Bank (DCO) and the Canadian banks in
the West Indies, 1926–45
Authors: MONTEITH KATHLEEN E. A. 
Published: July 2002

Kathleen E. A. Monteith, Competition between Barclays
Bank (DCO) and the Canadian banks in the West Indies, 1926–45This article examines the extent to which collusion ruled out competition
in banking, and assesses the nature and impact of this competition in order
to ascertain the degree to which Barclays Bank (DCO) faced any significant
challenge to its position within the region. It is shown that the rigidity
which is assumed to be characteristic of collusive agreements was not present,
and that competition existed in the commercial banking market in the West
Indies during this period. It is also shown that non-price competition existed
in many forms, and was capable of leading to a bank's position being usurped
by another.
HoNOSCA: Is the Enthusiasm Justified?
Authors: Jaffa Tony 
Published: July 2002

I have what I consider to be a healthy scepticism regarding
new assessment instruments. Many of these are announced
with great enthusiasm but fairly rapidly disappear or are
used mainly by those who have developed them and by
their associates.Although the tone of the paper by Gowers et al. (2000)
seems rather strong on enthusiasm and perhaps a little
lacking in its critical view, I do have great respect for
colleagues associated with development of HoNOSCA
and other respected colleagues talk well of it. Clearly, it
deserves careful scrutiny. For me relevant questions
include: ‘Is it easy to use?’, ‘Is it useful in terms of
describing a patient population?’ and ‘Is it useful in
looking at outcome?’
Laccase Down-Regulation Causes Alterations in Phenolic Metabolism and Cell Wall Structure in Poplar
Authors: Ranocha Philippe , Chabannes Matthieu , Chamayou Simon , Danoun Saı̈da , Jauneau Alain , Boudet Alain-M. , Goffner Deborah 
Published: July 2002

Abstract
Laccases are encoded by multigene families in plants. Previously, we reported the cloning and characterization of five divergent laccase genes from poplar (Populus trichocarpa) xylem. To investigate the role of individual laccase genes in plant development, and more particularly in lignification, three independent populations of antisense poplar plants, lac3AS, lac90AS, andlac110AS with significantly reduced levels of laccase expression were generated. A repression of laccase gene expression had no effect on overall growth and development. Moreover, neither lignin content nor composition was significantly altered as a result of laccase suppression. However, one of the transgenic populations,lac3AS, exhibited a 2- to 3-fold increase in total soluble phenolic content. As indicated by toluidine blue staining, these phenolics preferentially accumulate in xylem ray parenchyma cells. In addition, light and electron microscopic observations oflac3AS stems indicated that lac3 gene suppression led to a dramatic alteration of xylem fiber cell walls. Individual fiber cells were severely deformed, exhibiting modifications in fluorescence emission at the primary wall/middle lamella region and frequent sites of cell wall detachment. Although a direct correlation between laccase gene expression and lignification could not be assigned, we show that the gene product of lac3 is essential for normal cell wall structure and integrity in xylem fibers.lac3AS plants provide a unique opportunity to explore laccase function in plants.
Biochemical Characterization of the Extracellular Phosphatases Produced by Phosphorus-Deprived Chlamydomonas reinhardtii
Authors: Quisel J. D. , Wykoff D. D. , Grossman A. R. 
Published: July 2002

Abstract
We have examined the extracellular phosphatases produced by the terrestrial green alga Chlamydomonas reinhardtii in response to phosphorus deprivation. Phosphorus-deprived cells increase extracellular alkaline phosphatase activity 300-fold relative to unstarved cells. The alkaline phosphatases are released into the medium by cell-wall-deficient strains and by wild-type cells after treatment with autolysin, indicating that they are localized to the periplasm. Anion-exchange chromatography and analysis by nondenaturing polyacrylamide gel electrophoresis revealed that there are two major inducible alkaline phosphatases. A calcium-dependent enzyme composed of 190-kD glycoprotein subunits accounts for 85 to 95% of the alkaline phosphatase activity. This phosphatase has optimal activity at pH 9.5 and a Km of 120 to 262 [mu]M for all physiological substrates tested, with the exception of phytic acid, which it cleaved with a 50-fold lower efficiency. An enzyme with optimal activity at pH 9 and no requirement for divalent cations accounts for 2 to 10% of the alkaline phosphatase activity. This phosphatase was only able to efficiently hydrolyze arylphosphates. The information reported here, in conjunction with the results of previous studies, defines the complement of extracellular phosphatases produced by phosphorus-deprived Chlamydomonas cells.
Molecular Characterization of Photomixotrophic Tobacco Cells Resistant to Protoporphyrinogen Oxidase-Inhibiting Herbicides
Authors: Watanabe Naohide , Che Fang-Sik , Iwano Megumi , Takayama Seiji , Nakano Takeshi , Yoshida Shigeo , Isogai Akira 
Published: July 2002

AbstractPeroxidizing herbicides inhibit protoporphyrinogen oxidase (Protox), the last enzyme of the common branch of the chlorophyll- and heme-synthesis pathways. There are two isoenzymes of Protox, one of which is located in the plastid and the other in the mitochondria. Sequence analysis of the cloned Protox cDNAs showed that the deduced amino acid sequences of plastidial and mitochondrial Protox in wild-type cells and in herbicide-resistant YZI-1S cells are the same. The level of plastidial Protox mRNA was the same in both wild-type and YZI-1S cells, whereas the level of mitochondrial Protox mRNA YZI-1S cells was up to 10 times the level of wild-type cells. Wild-type cells were observed by fluorescence microscopy to emit strong autofluorescence from chlorophyll. Only a weak fluorescence signal was observed from chlorophyll in YZI-1S cells grown in the Protox inhibitorN-(4-chloro-2-fluoro-5-propagyloxy)-phenyl-3,4,5,6-tetrahydrophthalimide. Staining with DiOC6 showed no visible difference in the number or strength of fluorescence between wild-type and YZI-1S mitochondria. Electron micrography of YZI-1S cells showed that, in contrast to wild-type cells, the chloroplasts of YZI-1S cells grown in the presence ofN-(4-chloro-2-fluoro-5-propagyloxy)-phenyl-3,4,5,6-tetrahydrophthalimide exhibited no grana stacking. These results suggest that the herbicide resistance of YZI-1S cells is due to the overproduction of mitochondrial Protox.
Plastid Sedimentation Kinetics in Roots of Wild-Type and Starch-Deficient Mutants of Arabidopsis1
Authors: MacCleery Scott A. , Kiss John Z. 
Published: July 2002

AbstractSedimentation and movement of plastids in columella cells of the root cap were measured in seedlings of wild-type, a reduced starch mutant, and a starchless mutant of Arabidopsis. To assay for sedimentation, we used both linear measurements and the change of angle from the cell center as indices in vertical and reoriented plants with the aid of computer-assisted image analysis. Seedlings were fixed at short periods after reorientation, and plastid sedimentation correlated with starch content in the three strains of Arabidopsis. Amyloplasts of wild-type seedlings showed the greatest sedimentation, whereas plastids of the starchless mutant showed no significant sedimentation in the vertically grown and reoriented seedlings. Because previous research has shown that a full complement of starch is needed for full gravitropic sensitivity, this study correlates increased sensitivity with plastid sedimentation. However, although plastid sedimentation contributed to gravisensitivity, it was not required, because the gravitropic starchless mutant had plastids that did not sediment. This is the first study, to our knowledge, to measure plastid sedimentation in Arabidopsis roots after reorientation of seedlings. Taken together, the results of this study are consistent with the classic plastid-based and protoplast-based models of graviperception and suggest that multiple systems of perception exist in plant cells.
Vacuolar H+-ATPase Is Expressed in Response to Gibberellin during Tomato Seed Germination
Authors: Cooley Michael B. , Yang Hong , Dahal Peetambar , Mella R. Alejandra , Downie A. Bruce , Haigh Anthony M. , Bradford Kent J. 
Published: July 2002

Abstract
Completion of germination (radicle emergence) by gibberellin (GA)-deficient (gib-1) mutant tomato (Lycopersicon esculentum Mill.) seeds is dependent upon exogenous GA, because weakening of the endosperm tissue enclosing the radicle tip requires GA. To investigate genes that may be involved in endosperm weakening or embryo growth, differential cDNA display was used to identify mRNAs differentially expressed in gib-1 seeds imbibed in the presence or absence of GA4+7. Among these was a GA-responsive mRNA encoding the 16-kD hydrophobic subunit c of the V0 membrane sector of vacuolar H+-translocating ATPases (V-ATPase), which we termed LVA-P1. LVA-P1 mRNA expression in gib-1 seeds was dependent on GA and was particularly abundant in the micropylar region prior to radicle emergence. Both GA dependence and tissue localization ofLVA-P1 mRNA expression were confirmed directly in individual gib-1 seeds using tissue printing.LVA-P1 mRNA was also expressed in wild-type seeds during development and germination, independent of exogenous GA. Specific antisera detected protein subunits A and B of the cytoplasmic V1 sector of the V-ATPase holoenzyme complex ingib-1 seeds only in the presence of GA, and expression was localized to the micropylar region. The results suggest that V-ATPase plays a role in GA-regulated germination of tomato seeds.
Basipetal Auxin Transport Is Required for Gravitropism in Roots of Arabidopsis
Authors: Rashotte Aaron M. , Brady Shari R. , Reed Robyn C. , Ante Sandra J. , Muday Gloria K. 
Published: July 2002

Abstract
Auxin transport has been reported to occur in two distinct polarities, acropetally and basipetally, in two different root tissues. The goals of this study were to determine whether both polarities of indole-3-acetic acid (IAA) transport occur in roots of Arabidopsis and to determine which polarity controls the gravity response. Global application of the auxin transport inhibitor naphthylphthalamic acid (NPA) to roots blocked the gravity response, root waving, and root elongation. Immediately after the application of NPA, the root gravity response was completely blocked, as measured by an automated video digitizer. Basipetal [3H]IAA transport in Arabidopsis roots was inhibited by NPA, whereas the movement of [14C]benzoic acid was not affected. Inhibition of basipetal IAA transport by local application of NPA blocked the gravity response. Inhibition of acropetal IAA transport by application of NPA at the root-shoot junction only partially reduced the gravity response at high NPA concentrations. Excised root tips, which do not receive auxin from the shoot, exhibited a normal response to gravity. The Arabidopsis mutant eir1, which has agravitropic roots, exhibited reduced basipetal IAA transport but wild-type levels of acropetal IAA transport. These results support the hypothesis that basipetally transported IAA controls root gravitropism in Arabidopsis.
The rug3 Locus of Pea Encodes Plastidial Phosphoglucomutase
Authors: Harrison Christopher J. , Mould Ruth M. , Leech Mark J. , Johnson Susan A. , Turner Lynda , Schreck Sabine L. , Baird Kathleen M. , Jack Peter L. , Rawsthorne Stephen , Hedley Cliff L. , Wang Trevor L. 
Published: July 2002

Abstract
Two cDNA clones were isolated from pea (Pisum sativum L.) and their deduced amino acid sequences shown to have significant homology to phosphoglucomutases from eukaryotic and prokaryotic sources. The longer cDNA contained a putative transit-peptide-encoding sequence, supporting the hypothesis that the isolated clones represent the cytosolic and plastidial isoforms of phosphoglucomutase in pea. Plastid protein import assays confirmed that the putative plastidial isoform was targeted to the plastid stroma where it was proteolytically processed. Expression, co-segregation, linkage, and molecular analyses have confirmed that therug3 locus of pea encodes plastidial phosphoglucomutase. Mutations at this locus result in a near-starchless phenotype of the plant.
Genetic Enhancement of Fatty Acid Synthesis by Targeting Rat Liver ATP:Citrate Lyase into Plastids of Tobacco
Authors: Rangasamy Dhandapani , Ratledge Colin 
Published: July 2002

AbstractATP:citrate lyase (ACL) catalyzes the conversion of citrate to acetyl-coenzyme A (CoA) and oxaloacetate and is a key enzyme for lipid accumulation in mammals and oleaginous yeasts and fungi. To investigate whether heterologous ACL genes can be targeted and imported into the plastids of plants, a gene encoding a fusion protein of the rat liver ACL with the transit peptide for the small subunit of ribulose bisphosphate carboxylase was constructed and introduced into the genome of tobacco. This was sufficient to provide import of the heterologous protein into the plastids. In vitro assays of ACL in isolated plastids showed that the enzyme was active and synthesized acetyl-CoA. Overexpression of the rat ACL gene led to up to a 4-fold increase in the total ACL activity; this increased the amount of fatty acids by 16% but did not cause any major change in the fatty acid profile. Therefore, increasing the availability of acetyl-CoA as a substrate for acetyl-CoA carboxylase and subsequent reactions of fatty acid synthetase has a slightly beneficial effect on the overall rate of lipid synthesis in plants.
Cell Wall and Membrane-Associated Exo-β-d-Glucanases from Developing Maize Seedlings
Authors: Kim Jong-Bum , Olek Anna T. , Carpita Nicholas C. 
Published: July 2002

Abstract
A β-d-glucan exohydrolase was purified from the cell walls of developing maize (Zea mays L.) shoots. The cell wall enzyme preferentially hydrolyzes the non-reducing terminal glucosyl residue from (1→3)-β-d-glucans, but also hydrolyzes (1→2)-, (1→6)-, and (1→4)-β-d-glucosyl units in decreasing order of activity. Polyclonal antisera raised against the purified exo-β-d-glucanase (ExGase) were used to select partial-length cDNA clones, and the complete sequence of 622 amino acid residues was deduced from the nucleotide sequences of the cDNA and a full-length genomic clone. Northern gel-blot analysis revealed what appeared to be a single transcript, but three distinct polypeptides were detected in immunogel-blot analyses of the ExGases extracted from growing coleoptiles. Two polypeptides appear in the cell wall, where one polypeptide is constitutive, and the second appears at the time of the maximum rate of elongation and reaches peak activity after elongation has ceased. The appearance of the second polypeptide coincides with the disappearance of the mixed-linkage (1→3),(1→4)-β-d-glucan, whose accumulation is associated with cell elongation in grasses. The third polypeptide of the ExGase is an extrinsic protein associated with the exterior surface of the plasma membrane. Although the activity of the membrane-associated ExGase is highest against (1→3)-β-d-glucans, the activity against (1→4)-β-d-glucan linkages is severely attenuated and, therefore, the enzyme is unlikely to be involved with turnover of the (1→3),(1→4)-β-d-glucan. We propose three potential functions for this novel ExGase at the membrane-wall interface.
The Role of Vacuolar Malate-Transport Capacity in Crassulacean Acid Metabolism and Nitrate Nutrition. Higher Malate-Transport Capacity in Ice Plant after Crassulacean Acid Metabolism-Induction and in Tobacco under Nitrate Nutrition
Authors: Lüttge Ulrich , Pfeifer Tanja , Fischer-Schliebs Elke , Ratajczak Rafael 
Published: July 2002

Abstract
Anion uptake by isolated tonoplast vesicles was recorded indirectly via increased H+-transport by H+-pumping of the V-ATPase due to dissipation of the electrical component of the electrochemical proton gradient, ΔμH+, across the membrane. ATP hydrolysis by the V-ATPase was measured simultaneously after the Palmgren test. Normalizing for ATP-hydrolysis and effects of chloride, which was added to the assays as a stimulating effector of the V-ATPase, a parameter, Jmal rel, of apparent ATP-dependent malate-stimulated H+-transport was worked out as an indirect measure of malate transport capacity. This allowed comparison of various species and physiological conditions. Jmal rel was high in the obligate crassulacean acid metabolism (CAM) species Kalanchoëdaigremontiana Hamet et Perrier, it increased substantially after CAM induction in ice plant (Mesembryanthemum crystallinum), and it was positively correlated with NO3 − nutrition in tobacco (Nicotiana tabacum). For tobacco this was confirmed by measurements of malate transport energized via the V-PPase. In ice plant a new polypeptide of 32-kD apparent molecular mass appeared, and a 33-kD polypeptide showed higher levels after CAM induction under conditions of higher Jmal rel. It is concluded that tonoplast malate transport capacity plays an important role in physiological regulation in CAM and NO3 −nutrition and that a putative malate transporter must be within the 32- to 33-kD polypeptide fraction of tonoplast proteins.
A novel target recognition revealed by calmodulin in complex with the basic helix–loop–helix transcription factor SEF2‐1/E2‐2
Authors: Larsson Göran , Schleucher Jürgen , Onions Jacqueline , Hermann Stefan , Grundström Thoman , Wijmenga Sybren S. 
Published: July 2002

AbstractCalmodulin is the predominant intracellular receptor for Ca2+signals, mediating the regulation of numerous cellular processes. It can inhibit the DNA binding of basic helix–loop–helix transcription factors by a direct interaction of a novel type. To structurally characterize this novel calmodulin‐target interaction, we decided to study the complex of calmodulin with a dimeric peptide corresponding to the DNA‐binding domains of the dimeric basic helix–loop–helix transcription factor SEF2‐1 (SEF2‐1mp) using NMR. Here, we report that the stoichiometry of the calmodulin:SEF2‐1mp complex is one dimeric peptide binding two calmodulin molecules. We also report the 1H, 13C, and 15N resonance assignments and the secondary structure of calmodulin in this for NMR large (∼38 kD) complex, as well as the 1H assignments and secondary structure of SEF2‐1mp. In addition, we determined the amide proton exchange rates of calmodulin and measured intermolecular calmodulin:SEF2‐1mp and calmodulin:calmodulin NOE contacts. The isotope‐filtered experiments show a large number of SEF2‐1mp to calmodulin NOE contacts indicating that a tight complex is formed, which is confirmed by an intermolecular calmodulin:calmodulin NOE contact. The secondary structure and amide proton exchange data show that the binding does not occur via the classical wraparound binding mode. Instead, the data indicate that calmodulin interacts with SEF2‐1mp in a more open conformation, although the hydrophobic surfaces of the N‐ and C‐terminal domains still form the main interaction sites. Interactions involving charged residues are also identified in agreement with the known relatively high sensitivity of the binding to ionic strength. Finally, the peptide does not form an α‐helix as in the classical wraparound binding mode.
Identification of four proteins from the small subunit of the mammalian mitochondrial ribosome using a proteomics approach
Authors: Koc Emine Cavdar , Burkhart William , Blackburn Kevin , Koc Hasan , Moseley Arthur , Spremulli Linda L. 
Published: July 2002

AbstractProteins in the small subunit of the mammalian mitochondrial ribosome were separated by two‐dimensional polyacrylamide gel electrophoresis. Four individual proteins were subjected to in‐gel Endoprotease Lys‐C digestion. The sequences of selected proteolytic peptides were obtained by electrospray tandem mass spectrometry. Peptide sequences obtained from in‐gel digestion of individual spots were used to screen human, mouse, and rat expressed sequence tag databases, and complete consensus cDNAs for these species were deduced in silico. The corresponding protein sequences were characterized by comparison to known ribosomal proteins in protein databases. Four different classes of mammalian mitochondrial small subunit ribosomal proteins were identified. Only two of these proteins have significant sequence similarities to ribosomal proteins from prokaryotes. These proteins are homologs to Escherichia coli S9 and S5 proteins. The presence of these newly identified mitochondrial ribosomal proteins are also investigated in the Drosophila melanogaster, Caenorhabditis elegans, and in the genomes of several fungi.
Effect of Tube Inclination on Pool Boiling Heat
Transfer
Authors: Kang M.-G. 
Published: July 2002

Abstract
An experimental parametric study of a tubular heat exchanger has been carried out under pool boiling conditions to determine effects of the tube inclination angle on pool boiling heat transfer. Through the study, it can be concluded that (1) tube inclination gives much change on pool boiling heat transfer and the effect of the inclination angle is more strongly observed in the smooth tube and (2) if a tube is properly inclined, enhanced heat transfer is expected due to the decrease in bubble slug formation on the tube surface and easy liquid access to the surface. [S0022-1481(00)01201-9]