bluuebunny/crossref_metadata_2025 huggingface dataset:
The impact of agronomic manipulation of early vigour in wheat on growth and yield in South Australia
Authors: Sloane D. H. G. , Gill G. S. , McDonald G. K.
Published: July 2004

The initial growth of wheat crops can be manipulated either by agronomic means, such as by increasing inputs of seed and fertiliser, or by genetic improvement in early vigour. Cultivars of wheat with enhanced early vigour are still not commercially available and so a series of experiments was conducted to examine the impact of increasing initial dry matter production and leaf area index by increasing sowing and nitrogen (N) rates on grain yield. Increasing the sowing rate and amount of N fertiliser applied significantly increased early dry matter production and leaf area, with the largest responses occurring when sowing rate was increased. However, there was little effect on yield. The increases in dry matter production that occurred early in the season as a result of the additional inputs diminished as the season progressed. Yield responses to the additional inputs depended on the seasonal distribution of rainfall and in particular the rainfall received in August and September when grains per m2 were being determined. Consequently, yield responses were affected more by changes in grain per m2 than by changes in grain weight, and the benefits of the improvements in early vigour were only realised when moisture availability was high during the immediate pre-anthesis and early grain filling period of growth.
High rainfall in August and September increased the responses in grains per m2 from increased sowing rate and N. When N was used to increase early growth, the response in grain weight was negatively correlated with increasing pre-anthesis rainfall, but there was no relationship with rainfall when sowing rate was used to increase early growth. This effect of N, in which responses in pre-anthesis growth were offset by reductions in grain weight, is consistent with the ‘haying-off’ effect that can occur with applications of N.
The results showed that increasing early vigour by increased inputs of seed and N fertiliser produce variable responses in grain yield. While improvements in vegetative growth occurred, the realisation of these gains only happened when rainfall in August and September was adequate. Basing improvements in early vigour only on agronomic manipulation appears to be associated with a relatively high level of risk, as it is difficult to control the balance between vegetative growth and the availability of soil moisture. Alternatively, the data suggest that the levels of early vigour under current agronomic practices may be adequate (>50 g/m2 shoot DM at late tillering stage), and only marginal gains may be achieved by promoting early growth by additional inputs.
Effects of pasture species mixture, management, and environment on the productivity and persistence of dairy pastures in south-west Victoria. 2. Plant population density and persistence
Authors: Nie Z. N. , Chapman D. F. , Tharmaraj J. , Clements R.
Published: July 2004

Poor persistence of perennial pastures, particularly perennial ryegrass (Lolium perenne)-based pasture, is a major problem for the dairy industry in southern Australia. The effects of pasture species mixture, management and environment on plant population density and persistence were studied in a field experiment at 2 sites for 4 years (1998–2001). Five pasture types, combined with 3 management treatments, were established on a light-textured soil at Naringal, and on a heavier-textured soil at Terang in south-west Victoria in April 1998. The 5 pasture types were: (1) Old persistent type; (2) District mix; (3) Stoloniferous clover; (4) Alternative grasses; and (5) High producing. Most of the types were ryegrass-based except for Alternative grasses that consisted of tall fescue (Festuca arundinacea), cocksfoot (Dactylis glomerata L.), and phalaris (Phalaris aquatica L.). The 3 management treatments involved different levels of fertiliser input and weed/pest control.
There were significant differences in sown grass tiller density between pasture types in all years. Tiller density of the Alternative grasses remained at around the same level (95–105%) as its establishment tiller density, compared with only 55–62% for ryegrass-based pastures 3–4 years after sowing. Inclusion of stoloniferous white clover cvv. Prestige and Sustain significantly increased sown legume density in 3 out of 4 years. However, the overall legume density was low across all treatments. There was a significant negative exponential relationship between density of sown and volunteer species (predominantly annual grasses and broadleaf weeds). Soil fertility did not affect pasture persistence due to a high basal fertility level at both sites. Pasture persistence was poorer on the light-textured soil than on the heavier soil where soil moisture stress was a major limiting factor. Higher endophyte incidence in perennial ryegrass pasture appeared to improve its persistence. The results suggest that the sown species density should be maintained at >3000 growing points/m2 for ryegrass-based pasture types and >2300 growing points/m2 for Alternative grasses, to achieve a pasture composition with over 70% of sown species.
Impact of short-term exposure to cold night temperatures on early development of cotton (Gossypium hirsutum L.)
Authors: Bange M. P. , Milroy S. P.
Published: July 2004

Regression analysis of field data has indicated that minimum daily temperatures below 11°C delay the development of cotton (Gossypium hirsutum L.) seedlings beyond what would be expected based on the accumulated degree-day sum. In Australian cotton production systems, events where the minimum daily temperature falls below this value are referred to as ‘cold shocks’. The number of cold shocks is used by growers and advisors in assessing retardation of crops in their areas. However, this effect has not been tested explicitly. The aim of this work was to empirically assess effects of cold shock on pre-flower development of cotton plants. Cotton seedlings were grown in controlled-temperature glasshouses. Plants were transferred to cold chambers ranging from 5 to 22°C during the night period for durations from 3 to 10 days. Negative effects were not seen until plants had been exposed to at least 10 nights at 10°C, or for at least 5 nights at 5°C. When differences were generated it did not delay development to first square any more than 4 days, nor was the effect consistent. These differences translated into delays to first flower, but had little effect on plant morphology, or on dry weight measured soon after flowering. In one experiment, a significant reduction in leaf photosynthesis was measured at two times of day on the day after cold shock at 5°C. Improving understanding of the effects of temperature extremes on cotton growth and development will help in developing more functional decision-support tools and field management strategies.
Screening rice varieties for allelopathic potential against arrowhead (Sagittaria montevidensis), an aquatic weed infesting Australian Riverina rice crops
Authors: Seal Alexa N. , Pratley James E. , Haig Terry , Lewin Laurie G.
Published: July 2004

Twenty-eight rice varieties with different countries of origin, maturity and stage of improvement were screened in the laboratory for allelopathic potential against arrowhead. Initial rice-density experiments established appropriate bioassay parameters and demonstrated that arrowhead response to rice root exudates follows a typical dose–response curve. Results from the equal compartment agar method (ECAM) bioassay showed that a range of allelopathic potential exists in rice germplasm. This work, together with other published studies suggests such potential to be species specific. In this study, the degree of root inhibition ranged from 26.6 to 99.7%. The potential allelopathic effect of arrowhead on rice seedlings was determined to be negligible.
Multi-site evaluation on acid soils of a Phalaris aquatica × P. arundinacea × P. aquatica backcross population bred for acid soil tolerance
Authors: Culvenor R. A. , Wood J. T. , Avery A. L. , Dempsey W. , McDonald S. E. , Ronnfeldt G. , Veness P. E.
Published: July 2004

Half-sib families in the AT98 Phalaris aquatica × P. arundinacea × P. aquatica backcross population bred for acid soil tolerance were compared for establishment, persistence, and yield with phalaris (P. aquatica L.) controls and cocksfoot (Dactylis glomerata L. cv. Porto) at 4 sites in south-eastern Australia with the aim of selecting the parents of a new cultivar. The sites had strongly acid soils but differed in parent material, pH profile, soil fertility, and suitability for phalaris.
Establishment by AT98 was clearly superior to all phalaris controls and similar to cocksfoot in an acid soil high in Al to depth at Chiltern, north-eastern Victoria, after sowing in early spring 2000. It was considered likely that better establishment by AT98 was due to its higher Al tolerance. In contrast, little variation in establishment was observed at 3 other sites sown in late autumn 1999, possibly due to a longer period free of moisture stress compared with the later sown Chiltern site. Once established, the control cultivars of phalaris at the autumn-sown sites in general persisted and yielded similarly to the mean of the AT98 families.
Significant family variation was observed and predicted heritability on a family mean basis was high for persistence measured as basal frequency and moderately high for yield in the third year. Family by site interaction was relatively low for both attributes. A cultivar based on the best families should give more reliable establishment on acid soils high in Al under conditions where rapid root growth to depth is needed for survival, and give more flexibility of sowing date on these soils. Its best performance relative to cv. Landmaster in terms of third-year yield was predicted to occur on granite-derived soils in north-eastern Victoria.
Recovery and composition of endogenous protein collected at the terminal ileum as influenced by the age of broiler chickens
Authors: Ravindran V. , Hendriks W. H.
Published: July 2004

The recovery and composition of endogenous protein at the terminal ileum of broiler chickens were determined at 14 and 42 days post-hatching using the peptide alimentation method. The ileal endogenous flows of nitrogen and amino acids, expressed as mg/kg dry matter intake, differed (P < 0.05–0.01) between the two age groups, with flows increasing with age, except for lysine, histidine and glycine. The flows of lysine and histidine were unaffected (P > 0.05) by age, whereas a tendency (P = 0.07) for increased loss with age was observed for glycine. The amino acid profile of ileal endogenous protein, expressed as g/100 g crude protein, did not differ (P > 0.05) between 14-day- and 42-day-old broilers, suggesting that the relative proportions of the individual sources that contribute to the endogenous protein were similar at both ages. In both age groups, the most abundant amino acids in the ileal endogenous protein were glutamic acid, aspartic acid, proline, serine, glycine, and threonine. The present findings suggest that, when determining true digestibility, corrections using endogenous amino acid flows determined with broilers of a particular age to apparent amino acid digestibility values determined with birds of a different age would clearly result in less accurate true digestibility estimates.
Crop rotation effect on wheat grain yield as mediated by changes in the degree of water and nitrogen co-limitation
Authors: Sadras Victor O. , Baldock Jeff A. , Cox Jim W. , Bellotti W. D.
Published: July 2004

Theoretically, growth of stressed plants is maximised when all resources are equally limiting. The concept of co-limitation could be used to integrate key factors affected by crop rotation. This paper tested the hypothesis that the effect of crop rotation on the yield of wheat is partially mediated by changes in the degree of co-limitation between nitrogen and water. Four rotations were established on a sodic, supracalcic, red chromosol in a Mediterranean-type environment of southern Australia. Rotations included wheat grown after (a) faba bean harvested for grain, (b) faba bean incorporated as green manure, (c) ryegrass pasture, or (d) medic pasture; barley was grown after wheat in all cases. The response of wheat to the rotations during 3 growing seasons was analysed in terms of nitrogen and water co-limitation, and the response of barley was taken as a measure of the persistence of rotation effects. Daily scalars quantifying water and nitrogen stress effects on tissue expansion were calculated with a crop simulation model. These scalars were integrated in a series of seasonal indices to quantify the intensity of water (SW ) and nitrogen stress (SN ), the aggregated intensity of water and nitrogen stress (SWN ), the degree of water and nitrogen co-limitation (CWN ), and the integrated effect of stress and co-limitation (SCWN 25 CWN/SWN ). The expectation is that grain yield should be inversely proportional to stress intensity and directly proportional to degree of co-limitation, thus proportional to SCWN . Combination of rotations and seasons generated a wide variation in the amount of water and inorganic nitrogen in the 1-m soil profile at the time of wheat sowing. Plant-available water ranged from 33 to 107 mm, and inorganic nitrogen from 47 to 253 kg N/ha. Larger amounts of nitrogen were found after green-manured faba bean, and smaller after grass pasture. There was a consistent effect of rotation on wheat yield and grain protein content, which persisted in subsequent barley crops. Measured grain yield of wheat crops ranged from 2.5 to 4.8 t/ha. It was unrelated to water or nitrogen stresses taken individually, inversely related to the aggregated stress index SWN , and directly related to the CWN index of co-limitation. The combination of stress and co-limitation in a single index SCWN accounted for 65% of the variation in measured crop yield. This is a substantial improvement with respect to the stress effect quantified with SWN , which accounted for 43% of yield variation. It is concluded that rotation effects mediated by changes in the relative availability of water and nitrogen can be partially accounted for by degree of resource co-limitation.
Cyclization of Acetylenic Amides Using a Cationic Rhodium(I) Complex
Authors: Burling Suzanne , Field Leslie D. , Li Hsiu L. , Messerle Barbara A. , Shasha Adelle
Published: July 2004

The cationic Rh(I) dicarbonyl complex [{Rh(bim)(CO)2}+BPh4–] 1, containing a bidentate bisimidazolylmethane ligand [bim refers to bis(N-methylimidazol-2-yl)methane] acts as a catalyst for the cyclization of alkynyl amides to produce lactams and N-acyl heterocyclic compounds.
Anchimeric Assistance in Hydrogen-Atom Transfer to Bromine
Authors: Croft Anna K. , Easton Christopher J.
Published: July 2004

The free-radical benzylic brominations of series of phenylalanine derivatives and O-phenylalkyl benzoates and N-phenylalkylamides with N-bromosuccinimide exhibit anchimeric assistance by neighbouring ester and amido groups. Rate enhancement occurs through electron donation to the electropositive carbon centre that develops in the transition state of the hydrogen-atom transfer to bromine. The extent of the effect depends on the electron demand at the benzylic position and the electron-donating ability of the neighbouring group.
A role for Gα
12
/Gα
13
in p120
ctn
regulation
Authors: Krakstad Beate F. , Ardawatia Vandana V. , Aragay Anna M.
Published: July 2004

The catenin p120 (p120
ctn
) is an armadillo repeat domain protein that binds to cadherins and has been shown to facilitate strong cell–cell adhesion. We have investigated a possible link between heterotrimeric G proteins and p120
ctn
, and found that both Gα
12
and Gα
13
can completely and selectively abrogate the p120
ctn
-induced branching phenotype in different cell types. Consistent with these observations, the expression of Gα
12
or Gα
13
compensates for the reduction of Rho activity induced by p120
ctn
. On the other hand, p120
ctn
can be selectively coimmunoprecipitated with Gα
12
, and the coimmunoprecipitation was favored by activation of the G protein. A specific interaction between p120
ctn
and Gα
12
Q231L was also observed in
in vitro
binding experiments. In addition, p120
ctn
can be immunoprecipitated along with Gα
12
Q231L in L cells in absence of E-cadherin. Interestingly, the expression of Gα
12
Q231L increases the amount of p120
ctn
associated with E-cadherin. These findings demonstrate that Gα
12
and p120
ctn
are binding partners, and they also suggest a role for Gα
12
in regulating p120
ctn
activity and its interaction with cadherins. We propose that the Gα
12
–p120
ctn
interaction acts as a molecular switch, which regulates cadherin-mediated cell–cell adhesion.
Genome-wide analysis of repressor element 1 silencing transcription factor/neuron-restrictive silencing factor (REST/NRSF) target genes
Authors: Bruce Alexander W. , Donaldson Ian J. , Wood Ian C. , Yerbury Sally A. , Sadowski Michael I. , Chapman Michael , Göttgens Berthold , Buckley Noel J.
Published: July 2004

The completion of whole genome sequencing projects has provided the genetic instructions of life. However, whereas the identification of gene coding regions has progressed, the mapping of transcriptional regulatory motifs has moved more slowly. To understand how distinct expression profiles can be established and maintained, a greater understanding of these sequences and their trans-acting factors is required. Herein we have used a combined
in silico
and biochemical approach to identify binding sites [repressor element 1/neuron-restrictive silencer element (RE1/NRSE)] and potential target genes of RE1 silencing transcription factor/neuron-restrictive silencing factor (REST/NRSF) within the human, mouse, and
Fugu rubripes
genomes. We have used this genome-wide analysis to identify 1,892 human, 1,894 mouse, and 554
Fugu
RE1/NRSEs and present their location and gene linkages in a searchable database. Furthermore, we identified an
in vivo
hierarchy in which distinct subsets of RE1/NRSEs interact with endogenous levels of REST/NRSF, whereas others function as bona fide transcriptional control elements only in the presence of elevated levels of REST/NRSF. These data show that individual RE1/NRSE sites interact differentially with REST/NRSF within a particular cell type. This combined bioinformatic and biochemical approach serves to illustrate the selective manner in which a transcription factor interacts with its potential binding sites and regulates target genes. In addition, this approach provides a unique whole-genome map for a given transcription factor-binding site implicated in establishing specific patterns of neuronal gene expression.
Thyroid hormone receptor α is a molecular switch of cardiac function between fetal and postnatal life
Authors: Mai Wilfried , Janier Marc F. , Allioli Nathalie , Quignodon Laure , Chuzel Thomas , Flamant Frédéric , Samarut Jacques
Published: July 2004

Thyroid hormones are involved in the regulation of many physiological processes and regulate gene transcription by binding to their nuclear receptors TRα and TRβ. In the absence of triiodothyronine (T3), the unliganded receptors (aporeceptors) do bind DNA and repress the transcription of target genes. The role of thyroid hormone aporeceptors as repressors was observed in hypothyroid adult mice, but its physiological relevance in nonpathological hypothyroid conditions remained to be determined. Here we show that, in the normal mouse fetus, TRα aporeceptors repress heart rate as well as the expression of
TR
β and several genes encoding ion channels involved in cardiac contractile activity. Right after birth, when T3 concentration sharply increases, liganded TRα (holoreceptors) turn on the expression of some of these same genes concomitantly with heart rate increase. These data describe a physiological situation under which conversion of TRα from apo-receptors into holo-receptors, upon changes in T3 availability, plays a determinant role in a developmental process.
Template-assisted filament growth by parallel stacking of tau
Authors: Margittai Martin , Langen Ralf
Published: July 2004

Tau Filaments are found in >20 neurodegenerative diseases. Yet, because of their enormous molecular weights and poor tendency to form highly ordered 3D crystal lattices, they have evaded high-resolution structure determination. Here, we studied 25 derivatized tau mutants by using electron paramagnetic resonance and fluorescence spectroscopy to report structural details of tau filaments. Based on strong spin exchange and pyrene excimer formation of core residues, we find that individual tau proteins form single molecule layers along the fiber axis that perfectly stack on top of each other by in-register, parallel alignment of β-strands. We suggest a model of filament growth wherein the existing filament serves as a template for the incoming, unfolded tau molecule, resulting in a new structured layer with maximized hydrogen-bonded contact surface and side-chain stacking.
Switching desaturase enzyme specificity by alternate subcellular targeting
Authors: Heilmann Ingo , Pidkowich Mark S. , Girke Thomas , Shanklin John
Published: July 2004

The functionality, substrate specificity, and regiospecificity of enzymes typically evolve by the accumulation of mutations in the catalytic portion of the enzyme until new properties arise. However, emerging evidence suggests enzyme functionality can also be influenced by metabolic context. When the plastidial
Arabidopsis
16:0Δ
7
desaturase FAD5 (ADS3) was retargeted to the cytoplasm, regiospecificity shifted 70-fold, Δ
7
to Δ
9
. Conversely, retargeting of two related cytoplasmic 16:0Δ
9
Arabidopsis
desaturases (ADS1 and ADS2) to the plastid, shifted regiospecificity ≈25-fold, Δ
9
to Δ
7
. All three desaturases exhibited Δ
9
regiospecificity when expressed in yeast, with desaturated products found predominantly on phosphatidylcholine. Coexpression of each enzyme with cucumber monogalactosyldiacylglycerol (MGDG) synthase in yeast conferred Δ
7
desaturation, with 16:1Δ
7
accumulating specifically on the plastidial lipid MGDG. Positional analysis is consistent with ADS desaturation of 16:0 on MGDG. The lipid headgroup acts as a molecular switch for desaturase regiospecificity. FAD5 Δ
7
regiospecificity is thus attributable to plastidial retargeting of the enzyme by addition of a transit peptide to a cytoplasmic Δ
9
desaturase rather than the numerous sequence differences within the catalytic portion of ADS enzymes. The MGDG-dependent desaturase activity enabled plants to synthesize 16:1Δ
7
and its abundant metabolite, 16:3Δ
7,10,13
. Bioinformatics analysis of the
Arabidopsis
genome identified 239 protein families that contain members predicted to reside in different subcellular compartments, suggesting alternative targeting is widespread. Alternative targeting of bifunctional or multifunctional enzymes can exploit eukaryotic subcellular organization to create metabolic diversity by permitting isozymes to interact with different substrates and thus create different products in alternate compartments.
Central role of suppressors of cytokine signaling proteins in hepatic steatosis, insulin resistance, and the metabolic syndrome in the mouse
Authors: Ueki Kohjiro , Kondo Tatsuya , Tseng Yu-Hua , Kahn C. Ronald
Published: July 2004

Insulin resistance, obesity, diabetes, dyslipidemia, and nonalcoholic fatty liver are components of the metabolic syndrome, a disease complex that is increasing at epidemic rates in westernized countries. Although proinflammatory cytokines have been suggested to contribute to the development of these disorders, the molecular mechanism is poorly understood. Here we show that overexpression of suppressors of cytokine signaling (SOCS)-1 and SOCS-3 in liver causes insulin resistance and an increase in the key regulator of fatty acid synthesis in liver, sterol regulatory element-binding protein (SREBP)-1c. Conversely, inhibition of SOCS-1 and -3 in obese diabetic mice improves insulin sensitivity, normalizes the increased expression of SREBP-1c, and dramatically ameliorates hepatic steatosis and hypertriglyceridemia. In obese animals, increased SOCS proteins enhance SREBP-1c expression by antagonizing STAT3-mediated inhibition of SREBP-1c promoter activity. Thus, SOCS proteins play an important role in pathogenesis of the metabolic syndrome by concordantly modulating insulin signaling and cytokine signaling.
RETRACTED:
Arabidopsis
myosin XI mutant is defective in organelle movement and polar auxin transport
Authors: Holweg Carola , Nick Peter
Published: July 2004

Myosins are eukaryotic molecular motors moving along actin filaments. Only a small set of myosin classes is present in plants, in which myosins have been found to play a role in cytoplasmic streaming and chloroplast movement. Whereas most studies have been done on green algae, more recent data suggest a role of higher plant myosin at the postcytokinetic cell wall. Here we characterize a loss-of-function mutation for a myosin of plant-specific class XI and demonstrate myosin functions during plant development in
Arabidopsis
. T-DNA insertion in
MYA2
caused pleiotropic effects, including flower sterility and dwarf growth. Elongation of epidermal cells, such as in hypocotyls and anther filaments, was reduced by up to 50% of normal length. This effect on anther filaments is responsible for flower sterility. In the meristems of root tips, it was evident that cell division was delayed and that cell plates were mislocated. Like
zwichel
, a kinesin-related mutation causing two-branched trichomes, the
mya2
knockout causes branching defects, but here the trichomes remained unbranched. Growth was also impaired in pollen tubes and root hairs, cells that are highly dependent on vesicle transport. A failure in vesicle flow could be directly confirmed, because cytoplasmic streaming of vesicles and, more so, of large endoplasmic reticulum-based organelles was slowed. The defect in vesicle trafficking was accompanied by failures in basipetal auxin transport, measured in stem segments of inflorescences. This result strongly suggests a causal link between auxin-dependent processes and the distribution of vesicles and membrane-bound molecules by plant myosin.
The serine/threonine kinase cyclin G-associated kinase regulates epidermal growth factor receptor signaling
Authors: Zhang Lei , Gjoerup Ole , Roberts Thomas M.
Published: July 2004

Cyclin G-associated kinase (GAK) is a serine/threonine kinase that features high homology outside its kinase domain with auxilin. Like auxilin, GAK has been shown to be a cofactor for uncoating clathrin vesicles
in vitro
. We investigated epidermal growth factor (EGF) receptor-mediated signaling in cells, in which GAK is down-regulated by small hairpin RNAs. Here, we report that down-regulation of GAK by small hairpin RNA has two pronounced effects on EGF receptor signaling: (
i
) the levels of receptor expression and tyrosine kinase activity go up by >50-fold; and (
ii
) the spectrum of downstream signaling is significantly changed. One very obvious result is a large increase in the levels of activated extracellular signal-regulated kinase 5 and Akt. These two effects of GAK down-regulation result from, at least in part, alterations in receptor trafficking, the most striking of which is the persistence of EGF receptor in altered cellular compartment along with activated extracellular signal-regulated kinase 5. The alterations resulting from GAK down-regulation can have distinctive biological consequences: In CV1P cells, down-regulation of GAK results in outgrowth of cells in soft agar, raising the possibility that loss of GAK function may promote tumorigenesis.
Motif-grafted antibodies containing the replicative interface of cellular PrP are specific for PrP
Sc
Authors: Moroncini Gianluca , Kanu Nnennaya , Solforosi Laura , Abalos Gil , Telling Glenn C. , Head Mark , Ironside James , Brockes Jeremy P. , Burton Dennis R. , Williamson R. Anthony
Published: July 2004

Prion diseases are closely associated with the conversion of the cellular prion protein (PrP
C
) to an abnormal conformer (PrP
Sc
) [Prusiner, S. B. (1998)
Proc. Natl. Acad. Sci. USA
95, 13363–13383]. Monoclonal antibodies that bind epitopes comprising residues 96–104 and 133–158 of PrP
C
potently inhibit this process, presumably by preventing heterodimeric association of PrP
C
and PrP
Sc
, and suggest that these regions of PrP
C
may be critical components of the PrP
C
–PrP
Sc
replicative interface. We reasoned that transplanting PrP sequence corresponding to these regions into a suitable carrier molecule, such as an antibody, could impart specific recognition of disease-associated forms of PrP. To test this hypothesis, polypeptides containing PrP sequence between residues 89–112 or 136–158 were used to replace the extended heavy chain complementarity-determining region 3 of an IgG antibody specific for the envelope glycoprotein of HIV-1. Herein the resulting engineered PrP-IgGs are shown to bind specifically to infective fractions of PrP in mouse, human, and hamster prion-infected tissues, but not to PrP
C
, other cellular components, or the HIV-1 envelope. PrP
Sc
reactivity was abolished when the sequence of the PrP 89–112 and 136–158 grafts was mutated, scrambled, or N-terminally truncated. Our findings suggest that residues within the 89–112 and 136–158 segments of PrP
C
are key components of one face of the PrP
C
–PrP
Sc
complex. PrP
Sc
-specific antibodies produced by the approach described may find widespread application in the study of prion biology and replication and in the detection of infectious prions in human and animal materials.
Monoubiquitination and endocytosis direct γ-secretase cleavage of activated Notch receptor
Authors: Gupta-Rossi Neetu , Six Emmanuelle , LeBail Odile , Logeat Frédérique , Chastagner Patricia , Olry Annie , Israël Alain , Brou Christel
Published: July 2004

Activation of mammalian Notch receptor by its ligands induces TNFα-converting enzyme–dependent ectodomain shedding, followed by intramembrane proteolysis due to presenilin (PS)-dependent γ-secretase activity. Here, we demonstrate that a new modification, a monoubiquitination, as well as clathrin-dependent endocytosis, is required for γ-secretase processing of a constitutively active Notch derivative, ΔE, which mimics the TNFα-converting enzyme–processing product. PS interacts with this modified form of ΔE, ΔEu. We identified the lysine residue targeted by the monoubiquitination event and confirmed its importance for activation of Notch receptor by its ligand, Delta-like 1. We propose a new model where monoubiquitination and endocytosis of Notch are a prerequisite for its PS-dependent cleavage, and discuss its relevance for other γ-secretase substrates.
Extracellular calcium acts as a “third messenger” to regulate enzyme and alkaline secretion
Authors: Caroppo Rosa , Gerbino Andrea , Fistetto Gregorio , Colella Matilde , Debellis Lucantonio , Hofer Aldebaran M. , Curci Silvana
Published: July 2004

It is generally assumed that the functional consequences of stimulation with Ca2+-mobilizing agonists are derived exclusively from the second messenger action of intracellular Ca2+, acting on targets inside the cells. However, during Ca2+ signaling events, Ca2+ moves in and out of the cell, causing changes not only in intracellular Ca2+, but also in local extracellular Ca2+. The fact that numerous cell types possess an extracellular Ca2+ “sensor” raises the question of whether these dynamic changes in external [Ca2+] may serve some sort of messenger function. We found that in intact gastric mucosa, the changes in extracellular [Ca2+] secondary to carbachol-induced increases in intracellular [Ca2+] were sufficient and necessary to elicit alkaline secretion and pepsinogen secretion, independent of intracellular [Ca2+] changes. These findings suggest that extracellular Ca2+ can act as a “third messenger” via Ca2+ sensor(s) to regulate specific subsets of tissue function previously assumed to be under the direct control of intracellular Ca2+.
Mutations in orbit/mast reveal that the central spindle is comprised of two microtubule populations, those that initiate cleavage and those that propagate furrow ingression
Authors: Inoue Yoshihiro H. , Savoian Matthew S. , Suzuki Takao , Máthé Endre , Yamamoto Masa-Toshi , Glover David M.
Published: July 2004

We address the relative roles of astral and central spindle microtubules (MTs) in cytokinesis of Drosophila melanogaster primary spermatocytes. Time-lapse imaging studies reveal that the central spindle is comprised of two MT populations, “interior” central spindle MTs found within the spindle envelope and “peripheral” astral MTs that probe the cytoplasm and initiate cleavage furrows where they contact the cortex and form overlapping bundles. The MT-associated protein Orbit/Mast/CLASP concentrates on interior rather than peripheral central spindle MTs. Interior MTs are preferentially affected in hypomorphic orbit mutants, and consequently the interior central spindle fails to form or is unstable. In contrast, peripheral MTs still probe the cortex and form regions of overlap that recruit the Pav-KLP motor and Aurora B kinase. orbit mutants have disorganized or incomplete anillin and actin rings, and although cleavage furrows initiate, they ultimately regress. Our work identifies a new function for Orbit/Mast/CLASP and identifies a novel MT population involved in cleavage furrow initiation.
Mutations in sticky lead to defective organization of the contractile ring during cytokinesis and are enhanced by Rho and suppressed by Rac
Authors: D'Avino Pier Paolo , Savoian Matthew S. , Glover David M.
Published: July 2004

The contractile ring is a highly dynamic structure, but how this dynamism is accomplished remains unclear. Here, we report the identification and analysis of a novel Drosophila gene, sticky (sti), essential for cytokinesis in all fly proliferating tissues. sti encodes the Drosophila orthologue of the mammalian Citron kinase. RNA interference–mediated silencing of sti in cultured cells causes them to become multinucleate. Components of the contractile ring and central spindle are recruited normally in such STICKY-depleted cells that nevertheless display asymmetric furrowing and aberrant blebbing. Together with an unusual distribution of F-actin and Anillin, these phenotypes are consistent with defective organization of the contractile ring. sti shows opposite genetic interactions with Rho and Rac genes suggesting that these GTPases antagonistically regulate STICKY functions. Similar genetic evidence indicates that RacGAP50C inhibits Rac during cytokinesis. We discuss that antagonism between Rho and Rac pathways may control contractile ring dynamics during cytokinesis.
Scanning actions and environmental dynamism
Authors: Hough Jill R. , White Margaret A.
Published: July 2004

While it is generally accepted that scanning supports organizational adaptation to the environment, scanning behavior may vary with the amount of environmental change. Information processing perspectives suggest that scanning activity will increase in response to increasing environmental uncertainty. Yet, social cognition perspectives suggest that scanning decreases at high and low levels of uncertainty since useful information is either unattainable or is already known. Using a combined perspective in a strategic decision‐making context, this study hypothesized that scanning would be greatest at high and low levels of uncertainty to support identification of previously unexploited niches. Results indicate that the level of environmental dynamism combined with the manager's functional position explains scanning behavior.
The new normal: lessons learned from SARS for corporations operating in emerging markets
Authors: Day Brennan , Burnice Mckay Ruth , Ishman Michael , Chung Ed
Published: July 2004

The modern industrialized world was completely caught off guard by the recent SARS outbreak. Fortunately, for most organizations, the impact has been short lived, but management has been provided with a reminder of the impact of the external environment in a world of ever increasing globalization. As seen with the SARS outbreak, a lack of preparedness can have devastating effects on business and warrant inclusion in a business definition of a crisis. This paper uses the recent SARS epidemic as a background to highlight the importance of crisis planning, particularly in emerging economies, and suggests how organizations can address these concerns.
Perceptions of team performance
Authors: Karakowsky Leonard , McBey Kenneth , Chuang You‐Ta
Published: July 2004

The need to integrate men and women more effectively into team roles requires a fuller consideration of the dynamics of work‐team diversity and the consequences for both behavior and cognition among team members. Drawing from sociological and psychological perspectives, this study examines the influence of team gender composition and gender‐orientation of the task on members' perceptions of their team's performance. The participants for this study included 216 university students (108 men, 108 women) who were randomly assigned to one of three types of gender‐mixed teams – male‐dominated, female‐dominated and balanced‐gender work‐teams. Teams were required to generate, in a (videotaped) team meeting, a negotiation strategy for two business‐related cases. Self‐report instruments provided information regarding perceptions of team performance, and expert judges offered objective measures of team performance. The findings of this study offer striking evidence that team gender composition and the gender‐orientation of the task, can clearly affect member perceptions of the quality of their team's performance, regardless of the actual performance level achieved.
The love of money and work‐related attitudes
Authors: Li‐Ping Tang Thomas , Tillery Kenneth R. , Lazarevski Blagoja , Luna‐Arocas Roberto
Published: July 2004

This study examines the love of money and work‐related attitudes and identifies four money profiles based on a sample of citizens in the Republic of Macedonia. Achieving Money Worshipers (the highest scores on Factors Success, Motivator, and Budget and the lowest on Evil) had the highest active involvement in work activities. Careless Money Admirers (the lowest score on Factor Budget) had the highest external locus of control, the highest involvement, and lowest success avoidance. Apathetic Money Managers (the lowest scores on Factors Success and Motivator) had the highest internal locus of control and the lowest involvement. Money Repellent Individuals (the highest score on Factor Evil) had the lowest competitiveness and the highest success avoidance. Results provide the validity of the Love of Money Scale and the four money profiles.
Are natural diamond engagement rings forever?
Authors: Fram Eugene H. , Baron Robert
Published: July 2004

The tradition of celebrating an engagement with the gift of a natural diamond ring is largely an American custom. The custom helps drive 2002 retail sales of all diamonds in the USA ($27.4 billion) to 50 percent of global revenues. As a result, anything affecting the US diamond market, especially with diamond engagement rings, is likely to have worldwide implications for the natural diamond marketplace. Millions of American couples are now cohabitating prior to engagement or marriage, and the diamond industry can be facing some unusual social and economic forces. This article reports on a study a study to determine how a group of younger persons, mainly between the ages of 20 and 30, view the desirability of engagement ring purchasing.
Town centre management: how theory informs a strategic approach
Authors: Whyatt Georgina
Published: July 2004

Town centre management has gained recognition as a mechanism for urban renewal. The partnership between the private (mainly retailers) and the public (local authority) sectors has become accepted as a vital ingredient in achieving vitality and viability. The town centre management model has evolved from a tactical to a strategic role. This paper considers how current theory can inform the task of creating sustainable competitive advantage for an urban area. It discusses how the frameworks of partnership and services marketing should be adapted in order to meet the needs and expectations of today's consumer. The conclusion outlines how the management of urban areas can be more effective, now that the concept of town centre management has matured.
Development, disasters and vulnerability: a discussion of divergent theories and the need for their integration
Authors: McEntire David A.
Published: July 2004

The paper explores diverse theories of development and illustrates how they are also applied to the study of disaster. Shows that recent research from both the radical and conservative ideological camps recognizes the benefit of theoretical integration. Concludes with implications for disaster scholarship and management, paying special attention to the importance of the concept of vulnerability.
Managing secondary PTSD among personnel deployed in post‐conflict countries
Authors: Wilson John P. , Gielissen Hub
Published: July 2004

This paper investigates the nature of vicarious or secondary post‐traumatic stress disorder in relation to six Dutch organisations and their personnel working in Rwanda, a country heavily affected by genocide and war. Drawing from the literature and empirical research it is argued that a systematic approach can strongly contribute to a more coherent human resource management/human resource development cycle of environmental analysis; identification of job descriptions and person specifications; relationship of jobs, persons and teams; recruitment, selection and contracting; induction and training; deployment and management of individuals and teams; and finally, debriefing and counselling. In this way, there is greater potential for the organisation to achieve objectives and enable its expatriate workforce to handle the stressful conditions in which they may find themselves.
An integrative approach to disaster management and planning
Authors: Trim Peter R.J.
Published: July 2004

Although it is possible to prevent and contain both man made and natural disasters, it has to be said that the increase in the world's population is likely to increase further the frequency of a major disaster occurring. Disaster management and planning needs to be placed in a holistic setting, and new initiatives found in order to ensure that a disaster is viewed as a shared responsibility. One area that needs further attention is the concept of community policing and what community policing incorporates. Often, a disaster is on such a scale that local community leaders need to be consulted during the disaster limitation and containment stage. It is essential, therefore, that experts from overseas countries brought into the disaster arena, are able to communicate fully and openly with community leaders in order to gain the support of the community.
Innovation, construction SMEs and action learning
Authors: Davey Caroline L. , Powell James A. , Cooper Ian , Powell Jennifer E.
Published: July 2004

Action learning is intended to enable a group of professionals (a SET) to tackle work problems, develop solutions and reflect upon the success and failure of their actions. As part of the UK construction industry's drive to improve learning and performance, four SETs of small and medium‐sized enterprises (SMEs) were established. This paper evaluates the capacity of action learning to promote innovation and use of technologies within a CIOB‐funded SET located in Watford. Construction companies were unable to address real problems related to their day‐to‐day activities due to competition. Instead, they identified an industry‐wide issue – a lack of quality recruits – and marshalled resources to provide better careers advice and promote opportunities for builders. The role of action learning in empowering construction SMEs to contribute to industry change programmes is explored.
Determinants of rework in building construction projects
Authors: Love Peter E.D. , Edwards David J.
Published: July 2004

Rework represents the unnecessary effort of redoing a process or activity that is incorrectly implemented the first time. Using a structured questionnaire survey, the causes and costs of rework in 161 Australian construction projects were identified. Respondents were invited to indicate direct and indirect rework costs that would be subsequently combined to produce a total rework cost (TRC) figure. Stepwise linear multiple regression analysis was then used to determine a model that included an optimum mixture of significant variables that contributed or lead to a reduction in TRC for the projects sampled. The research revealed that reworkper secan negatively influence project safety. Client initiated changes and ineffective use of information technology by the design professionals were identified as being significant variables contributing to rework occurrence. Contrary to an earlier presupposition, design scope freezing was also identified as being a significant factor that can contribute to rework.
Bridging the skills gap: a regionally driven strategy for resolving the construction labour market crisis
Authors: Dainty Andrew R.J. , Ison Stephen G. , Root David S.
Published: July 2004

Econometric forecasts indicate that the UK construction industry faces a severe skills deficit in the foreseeable future. This paper details the results of a major labour market research projects, which canvassed the opinions of over 50 industry stakeholders within the East Midlands region of the UK. Focus groups were used to elicit the collective opinions of key clients, consultants, contractors, industry bodies and employers of all sizes. The key themes and requirements discussed by the participants are used to develop a conjoined strategy for bridging the industry's skills gap at a regional level. It is argued that this package of mutually supportive measures could provide a transferable strategy for addressing skills deficiencies in other regions, particularly given the espoused government aspiration to devolve labour market planning activities to provincial forums and regional development agencies.
International technology transfer: perceptions and reality of quality and reliability
Authors: Bennett David , Zhao Hongyu
Published: July 2004

Impressions about product quality and reliability can depend as much on perceptions about brands and country of origin as on data regarding performance and failure. This has implications for companies in developing countries that need to compete with importers. For manufacturers in industrialised countries it has implications for the value of transferred technologies. This article considers the issue of quality and reliability when technology is transferred between countries with different levels of development. It is based on UK and Chinese company case studies and questionnaire surveys undertaken among three company groups: UK manufacturers; Chinese manufacturers; Chinese users. Results show that all three groups recognise quality and reliability as important and support the premise that foreign technology based machines made in China carry a price premium over Chinese machines based on local technology. Closer examination reveals a number of important differences concerning the perceptions and reality of quality and reliability between the groups.