bluuebunny/crossref_metadata_2025 huggingface dataset:
The kinetochore protein Ndc10p is required for spindle stability and cytokinesis in yeast
Authors: Bouck David C. , Bloom Kerry S.
Published: April 2005

The budding yeast kinetochore is comprised of >60 proteins and associates with 120 bp of centromeric (CEN) DNA. Kinetochore proteins are highly dynamic and exhibit programmed cell cycle changes in localization. The CEN-specific histone, Cse4p, is one of a few stable kinetochore components and remains associated with CEN DNA throughout mitosis. In contrast, several other kinetochore proteins have been observed along interpolar microtubules and at the midzone during anaphase. The inner kinetochore protein, Ndc10p, is enriched at the spindle midzone in late anaphase. We show that Ndc10p is transported to the plus-ends of interpolar microtubules at the midzone during anaphase, a process that requires survivin (Bir1p), a member of the aurora kinase (Ipl1p) complex, and Cdc14p phosphatase. In addition, Ndc10p is required for essential non-kinetochore processes during mitosis. Cells lacking functional Ndc10p show defects in spindle stability during anaphase and failure to split the septin ring during cytokinesis. This latter phenotype leads to a cell separation defect in
ndc10–1
cells. We propose that Ndc10p plays a direct role in maintaining spindle stability during anaphase and coordinates the completion of cell division after chromosome segregation.
Comparative evolutionary genetics of spontaneous mutations affecting fitness in rhabditid nematodes
Authors: Baer Charles F. , Shaw Frank , Steding Catherine , Baumgartner Margaret , Hawkins Alicia , Houppert Andrew , Mason Nicole , Reed Marissa , Simonelic Kevin , Woodard Wayne , Lynch Michael
Published: April 2005

Deleterious mutations are of fundamental importance to all aspects of organismal biology. Evolutionary geneticists have expended tremendous effort to estimate the genome-wide rate of mutation and the effects of new mutations on fitness, but the degree to which genomic mutational properties vary within and between taxa is largely unknown, particularly in multicellular organisms. Beginning with two highly inbred strains from each of three species in the nematode family Rhabditidae (
Caenorhabditis briggsae
,
Caenorhabditis elegans
, and
Oscheius myriophila
), we allowed mutations to accumulate in the relative absence of natural selection for 200 generations. We document significant variation in the rate of decay of fitness because of new mutations between strains and between species. Estimates of the per-generation mutational decay of fitness were very consistent within strains between assays 100 generations apart. Rate of mutational decay in fitness was positively associated with genomic mutation rate and negatively associated with average mutational effect. These results provide unambiguous experimental evidence for substantial variation in genome-wide properties of mutation both within and between species and reinforce conclusions from previous experiments that the cumulative effects on fitness of new mutations can differ markedly among related taxa.
Conformational variability of matrix metalloproteinases: Beyond a single 3D structure
Authors: Bertini Ivano , Calderone Vito , Cosenza Marta , Fragai Marco , Lee Yong-Min , Luchinat Claudio , Mangani Stefano , Terni Beatrice , Turano Paola
Published: April 2005

The structures of the catalytic domain of matrix metalloproteinase 12 in the presence of acetohydroxamic acid and
N
-isobutyl-
N
-[4-methoxyphenylsulfonyl]glycyl hydroxamic acid have been solved by x-ray diffraction in the crystalline state at 1.0 and 1.3-Å resolution, respectively, and compared with the previously published x-ray structure at 1.2-Å resolution of the adduct with batimastat. The structure of the
N
-isobutyl-
N
-[4-methoxyphenylsulfonyl]glycyl hydroxamic acid adduct has been solved by NMR in solution. The three x-ray structures and the solution structure are similar but not identical to one another, the differences being sizably higher in the loops. We propose that many of the loops show a dynamical behavior in solution on a variety of time scales. Different conformations of some flexible regions of the protein can be observed as “frozen” in different crystalline environments. The mobility in solution studied by NMR reveals conformational equilibria in accessible time scales, i.e., from 10
–5
s to ms and more. Averaging of some residual dipolar couplings is consistent with further motions down to 10
–9
s. Finally, local thermal motions of each frozen conformation in the crystalline state at 100 K correlate well with local motions on the picosecond time scale. Flexibility/conformational heterogeneity in crucial parts of the catalytic domain is a rule rather than an exception in matrix metalloproteinases, and its extent may be underestimated by inspection of one x-ray structure. Backbone flexibility may play a role in the difficulties encountered in the design of selective inhibitors, whereas it may be a requisite for substrate binding and broad substrate specificity.
Escherichia coliK1 polysialic acidO-acetyltransferase gene,neuO, and the mechanism of capsule form variation involving a mobile contingency locus
Authors: Deszo Eric L. , Steenbergen Susan M. , Freedberg Darón I. , Vimr Eric R.
Published: April 2005

PotentialO-acetylation of the sialic acid residues ofEscherichia coliK1, groups W-135, Y, and C meningococci, and group BStreptococcuscapsular polysaccharides modifies their immunogenicity and susceptibility to glycosidases. Despite the biological importance ofO-acetylation, no sialic or polysialic acidO-acetyltransferase has been identified in any system. Here we show that theE. coliK1O-acetyltransferase encoded byneuOis genetically linked to the endo-neuraminidase tail protein gene of a chromosomal accretion element, designated CUS-3, with homology to lambdoid bacteriophage. Molecular epidemiological analysis established concordance betweenO-acetyltransferase and CUS-3 in a set ofE. coliK1 strains. DeletingneuOeliminated enzymatic activity, which was restored by complementation in trans, and confirmed by13C-NMR analysis of the acetylated product. Analysis of mutants that accumulate intracellular polysialic acid because of export defects (kpsMandkpsS) or an inability to synthesize the sialic acid precursor,N-acetylmannosamine (neuC), indicated that NeuO does not require constant association with its substrate for activity. DNA sequencing and PCR analysis ofneuOfrom strains that had undergone random capsule form variation showed that slip strand DNA mispairing or unequal recombination resulted in gain or loss of (5′-AAGACTC-3′)nheptanucleotide repeats (wheren≈ 14–39) located in theneuO5′ region. These repeats code for a previously undescribed structure designated the poly(Ψ) motif. The unexpected discovery of theneuOcontingency locus (hypervariable gene controlling expression of a surface epitope) inE. coli, and of a potential phage for redistributing variantneuOalleles, provides a robust system for investigating the functions of localized hypermutability in pathogen evolution.
Linearized path integral approach for calculating nonadiabatic time correlation functions
Authors: Bonella Sara , Montemayor Daniel , Coker David F.
Published: April 2005

We show that quantum time correlation functions including electronically nonadiabatic effects can be computed by using an approach in which their path integral expression is linearized in the difference between forward and backward nuclear paths while the electronic component of the amplitude, represented in the mapping formulation, can be computed exactly, leading to classical-like equations of motion for all degrees of freedom. The efficiency of this approach is demonstrated in some simple model applications.
A fullerene molecular tip can detect localized and rectified electron tunneling within a single fullerene–porphyrin pair
Authors: Nishino Tomoaki , Ito Takashi , Umezawa Yoshio
Published: April 2005

A fullerene molecular tip was used to detect electron tunneling from a single porphyrin molecule. Electron tunneling was found to occur locally from an electron-donating moiety of the porphyrin to the fullerene through charge-transfer interaction between them. In addition, electron tunneling within the single fullerene–porphyrin pair exhibited rectifying behavior in which electrons can be driven only at the direction from the porphyrin to the fullerene. It is demonstrated that localized electron tunneling enables us to spatially visualize the frontier orbital of the porphyrin involved in electron tunneling. In addition, rectification demonstrates that the fullerene–porphyrin pair constitutes a molecular rectifier. We believe that molecular tips bring insight into intermolecular electron transmission toward realization of molecular electronics as shown here.
Finds in Belize document Late Classic Maya salt making and canoe transport
Authors: McKillop Heather
Published: April 2005

How did people in preIndustrial ancient civilizations produce and distribute bulk items, such as salt, needed for everyday use by their large urban populations? This report focuses on the ancient Maya who obtained quantities of salt at cities in the interior of the Yucatan peninsula of Mexico, Belize, and Guatemala in an area where salt is scarce. I report the discovery of 41 Late Classic Maya saltworks (anno Domini600–900) in Punta Ycacos Lagoon on the south coast of Belize, including one with the first-known ancient Maya canoe paddle. The discoveries add important empirical information for evaluating the extent of surplus salt production and river transport during the height of Late Classic civilization in the southern Maya lowlands. The discovery of the saltworks indicates that there was extensive production and distribution of goods and resources outside the cities in the interior of the Yucatan. The discovery of a wooden canoe paddle from one of the Punta Ycacos saltworks, Ka'k' Naab', ties the production of salt to its inland transport by rivers and documents the importance of canoe trade between the coast and the interior during the Late Classic. Archaeological discovery of multiple saltworks on the Belizean coast represents surplus production of salt destined largely for the inland Peten Maya during their Late Classic peak, underscoring the importance of non-state-controlled workshop production in preIndustrial societies.
Exact solution of a jamming transition: Closed equations for a bootstrap percolation problem
Authors: De Gregorio Paolo , Lawlor Aonghus , Bradley Phil , Dawson Kenneth A.
Published: April 2005

Jamming, or dynamical arrest, is a transition at which many particles stop moving in a collective manner. In nature it is brought about by, for example, increasing the packing density, changing the interactions between particles, or otherwise restricting the local motion of the elements of the system. The onset of collectivity occurs because, when one particle is blocked, it may lead to the blocking of a neighbor. That particle may then block one of its neighbors, these effects propagating across some typical domain of size named the dynamical correlation length. When this length diverges, the system becomes immobile. Even where it is finite but large the dynamics is dramatically slowed. Such phenomena lead to glasses, gels, and other very long-lived nonequilibrium solids. The bootstrap percolation models are the simplest examples describing these spatio-temporal correlations. We have been able to solve one such model in two dimensions exactly, exhibiting the precise evolution of the jamming correlations on approach to arrest. We believe that the nature of these correlations and the method we devise to solve the problem are quite general. Both should be of considerable help in further developing this field.
Posttranslational processing of mouse and human BMP-15: Potential implication in the determination of ovulation quota
Authors: Hashimoto Osamu , Moore R. Kelly , Shimasaki Shunichi
Published: April 2005

There has been significant attention to the growing recognition that oocytes have a critical capacity to organize and govern surrounding somatic cells. Bone morphogenetic protein 15 (BMP-15) is an oocyte-secreted factor that has raised particular interest due to its established role in determining ovulation quota and female fertility in mammals. As a first step in determining whether there are species-specific differences in the BMP-15 system that may play causal roles in the differences in ovulation quota observed in different mammalian species, we here compare the molecular characteristics of BMP-15 of polyovulatory mice with that of monoovulatory humans. We found that, although human BMP-15 mature protein is readily produced, there are defects in the production of mouse BMP-15 mature protein in an
in vitro
system of transfected cells. The generation of chimeric constructs consisting of different combinations of mouse and human BMP-15 proregions, cleavage sites, and mature regions indicates that the defects in the production of mouse BMP-15 mature protein depend on the presence of the mouse BMP-15 proregion. The mouse proregion also caused a significant reduction in the production of human BMP-15 mature protein. The coexpression with a convertase cleavage enzyme, furin, results in complete processing of all these chimeras; however, no mouse mature protein is detected in either secreted or cell-confined forms except when associated with the human proregion. Based on the biological role of BMP-15, defects in the production of mouse BMP-15 mature protein could correlate with the high ovulation quota and litter size observed in mice.
On the conservative nature of intragenic recombination
Authors: Drummond D. Allan , Silberg Jonathan J. , Meyer Michelle M. , Wilke Claus O. , Arnold Frances H.
Published: April 2005

Intragenic recombination rapidly creates protein sequence diversity compared with random mutation, but little is known about the relative effects of recombination and mutation on protein function. Here, we compare recombination of the distantly related β-lactamases PSE-4 and TEM-1 to mutation of PSE-4. We show that, among β-lactamase variants containing the same number of amino acid substitutions, variants created by recombination retain function with a significantly higher probability than those generated by random mutagenesis. We present a simple model that accurately captures the differing effects of mutation and recombination in real and simulated proteins with only four parameters: (
i
) the amino acid sequence distance between parents, (
ii
) the number of substitutions, (
iii
) the average probability that random substitutions will preserve function, and (
iv
) the average probability that substitutions generated by recombination will preserve function. Our results expose a fundamental functional enrichment in regions of protein sequence space accessible by recombination and provide a framework for evaluating whether the relative rates of mutation and recombination observed in nature reflect the underlying imbalance in their effects on protein function.
Molecular organization of the Ndc80 complex, an essential kinetochore component
Authors: Wei Ronnie R. , Sorger Peter K. , Harrison Stephen C.
Published: April 2005

The four-protein Ndc80 complex, an essential kinetochore component conserved from yeast to humans, plays an indispensable role in proper chromosome alignment and segregation during mitosis. In higher eukaryotes, the homologous complex probably resides in the middle domain of the trilaminar kinetochore, linking centromeric heterochromatin with microtubule-associated structures. We have prepared recombinant Ndc80 complex by pairwise coexpression of its components (Ndc80p and Nuf2p; Spc24p and Spc25p) and shown that they form independently stable subcomplexes. Rotary shadowing electron microscopy, combined with limited proteolysis and antibody labeling, demonstrates that the heterotetrameric Ndc80 complex is an ≈570-Å-long rod, with globular regions at either end. The shaft contains α-helical coiled-coil segments from each of the two subcomplexes, linked end-to-end. When integrated with published observations derived from inactivating the components of Ndc80, the molecular organization we deduce suggests that the Spc24p/Spc25p end of the rod faces the centromere and the Ndc80p/Nuf2p end faces a spindle microtubule.
Identification of putative noncoding polyadenylated transcripts in
Drosophila melanogaster
Authors: Tupy Jonathan L. , Bailey Adina M. , Dailey Gina , Evans-Holm Martha , Siebel Christian W. , Misra Sima , Celniker Susan E. , Rubin Gerald M.
Published: April 2005

Analysis of EST and cDNA collections from a number of metazoan species has identified genes encoding long polyadenylated transcripts that do not contain ORFs of lengths typical for protein-encoding mRNAs. Noncoding functions of such polyadenylated transcripts have been elucidated in only a few examples. The corresponding genes neither contain hallmark sequence motifs nor appear to have been conserved across phyla. Thus, it is impossible to systematically identify new members of this class of gene by using sequence homology and traditional gene-finding algorithms that depend on protein-coding potential. Consequently, even their approximate number has not been established for any metazoan genome. We curated polyadenylated transcripts with limited protein-coding capacity from intergenic regions of the
Drosophila melanogaster
genome. We used RT-PCR assays, hybridization to RNA blots and whole-mount embryos, and computational analyses to characterize candidate transcripts. We verify the structures and expression of 17 distinct, likely non-protein-coding polyadenylated transcripts. We show that the expression of many of these transcripts is conserved in other
Drosophila
species, indicating that they have important biological functions.
Memory T cells have gene expression patterns intermediate between naïve and effector
Authors: Holmes Susan , He Michael , Xu Tong , Lee Peter P.
Published: April 2005

The biological basis underlying differentiation of naïve (NAI) T cells into effector (EFFE) and memory (MEM) cells is incompletely understood. Furthermore, whether NAI T cells serially differentiate into EFFE and then MEM cells (linear differentiation) or whether they concurrently differentiate into either EFFE or MEM cells (parallel differentiation) remains unresolved. We isolated NAI, EFFE, and MEM CD8+T cell subsets from human peripheral blood and analyzed their gene expression by using microarrays. We identified 156 genes that strongly differentiate NAI, EFFE, and MEM CD8+T cells; these genes provide previously unrecognized markers to help identify each cell type. Using several statistical approaches to analyze and group the data (standard heat-map and hierarchical clustering, a unique circular representation, multivariate analyses based on principal components, and a clustering method based on phylogenetic parsimony analysis), we assessed the lineage relationships between these subsets and showed that MEM cells have gene expression patterns intermediate between NAI and EFFE T cells. Our analysis suggests a common differentiation pathway to an intermediate state followed by a split into EFFE or MEM cells, hence supporting the parallel differentiation model. As such, conditions under which NAI T cells are activated may determine the magnitude of both EFFE and MEM cells, which arise subsequently. A better understanding of these conditions may be very useful in the design of future vaccine strategies to maximize MEM cell generation.
Developmental disruption of serotonin transporter function impairs cerebral responses to whisker stimulation in mice
Authors: Esaki Takanori , Cook Michelle , Shimoji Kazuaki , Murphy Dennis L. , Sokoloff Louis , Holmes Andrew
Published: April 2005

There is growing evidence that serotonin (5-hydroxtryptamine, 5-HT) has major influences on brain development in mammals. Genetic and pharmacological disruption of 5-HT signaling during early postnatal development in rodents causes neuroanatomical cortical abnormalities, including malformations in the somatosensory cortex. Possible functional consequences of this developmental perturbation by 5-HT are not yet understood. We have examined the effects of deletion of the 5-HT transporter (5-HTT) gene on somatosensory responses to sensory stimulation in mice. Local cerebral glucose utilization (lCMR
glc
) was measured by the quantitative 2-deoxy[
14
C]glucose method during unilateral whisker stimulation in awake adult mice. lCMR
glc
was increased by stimulation but to a markedly lesser extent in
5-HTT

–
/
–

mice than in
5-HTT

+
/
+

controls in each of four major stations in the whisker-to-barrel cortex pathway (the spinal and principal sensory trigeminal nuclei, the ventral posteromedial thalamic nucleus, and the barrel region of the somatosensory cortex). Lowering brain 5-HT levels by administration of the selective tryptophan hydroxylase inhibitor
p
-chlorophenylalanine on postnatal days 0 and 1 restored the metabolic responses to functional activation in the whisker-to-barrel cortex pathway in adult
5-HTT

–
/
–

mice. These results indicate that functional deficits in this pathway in
5-HTT

–
/
–

mice may be due to excessive postnatal 5-HT activity. With or without postnatal
p
-chlorophenylalanine treatment,
5-HTT

–
/
–

mice exhibited lower resting (unstimulated) lCMR
glc
than did
5-HTT

+
/
+

controls in the whisker-to-barrel cortex pathway and throughout the brain. These findings have implications for understanding the potential long-term consequences of genetic and pharmacological disruption of 5-HT neurotransmission on cerebral functions during critical periods of postnatal development.
Molecular recognition of an ADP-ribosylating
Clostridium botulinum
C3 exoenzyme by RalA GTPase
Authors: Holbourn Kenneth P. , Sutton J. Mark , Evans Hazel R. , Shone Clifford C. , Acharya K. Ravi
Published: April 2005

C3 exoenzymes (members of the ADP-ribosyltranferase family) are produced by
Clostridium botulinum
(C3bot1 and -2),
Clostridium limosum
(C3lim),
Bacillus cereus
(C3cer), and
Staphylococcus aureus
(C3stau1–3). These exoenzymes lack a translocation domain but are known to specifically inactivate Rho GTPases in host target cells. Here, we report the crystal structure of C3bot1 in complex with RalA (a GTPase of the Ras subfamily) and GDP at a resolution of 2.66 Å. RalA is not ADP-ribosylated by C3 exoenzymes but inhibits ADP-ribosylation of RhoA by C3bot1, C3lim, and C3cer to different extents. The structure provides an insight into the molecular interactions between C3bot1 and RalA involving the catalytic ADP-ribosylating turn–turn (ARTT) loop from C3bot1 and helix α4 and strand β6 (which are not part of the GDP-binding pocket) from RalA. The structure also suggests a molecular explanation for the different levels of C3-exoenzyme inhibition by RalA and why RhoA does not bind C3bot1 in this manner.
The CNS role of Toll-like receptor 4 in innate neuroimmunity and painful neuropathy
Authors: Tanga Flobert Y. , Nutile-McMenemy Nancy , DeLeo Joyce A.
Published: April 2005

Neuropathic pain remains a prevalent and persistent clinical problem because of our incomplete understanding of its pathogenesis. This study demonstrates for the first time, to our knowledge, a critical role for CNS innate immunity by means of microglial Toll-like receptor 4 (TLR4) in the induction phase of behavioral hypersensitivity in a mouse and rat model of neuropathy. We hypothesized that after L5 nerve transection, CNS neuroimmune activation and subsequent cytokine expression are triggered by the stimulation of microglial membrane-bound TLR4. To test this hypothesis, experiments were undertaken to assess tactile and thermal hypersensitivity in genetically altered (i.e., TLR4 knockout and point-mutant) mice after L5 nerve transection. In a complementary study, TLR4 antisense oligodeoxynucleotide (ODN) was administered intrathecally to L5 spinal nerve injured rats to reduce the expression of spinal TLR4. Both the genetically altered mice and the rats treated with TLR4 antisense ODN displayed significantly attenuated behavioral hypersensitivity and decreased expression of spinal microglial markers and proinflammatory cytokines as compared with their respective control groups. This finding shows that TLR4 contributes to the initiation of CNS neuroimmune activation after L5 nerve transection. Further understanding of this early, specific, innate CNS/microglial response and how it leads to sustained glial/neuronal hypersensitivity may point to new therapies for the prevention and treatment of neuropathic pain syndromes.
The contribution of GABA to glutamate/glutamine cycling and energy metabolism in the rat cortexin vivo
Authors: Patel Anant B. , de Graaf Robin A. , Mason Graeme F. , Rothman Douglas L. , Shulman Robert G. , Behar Kevin L.
Published: April 2005

Previous studies have shown that the glutamate/glutamine (Glu/Gln) neurotransmitter cycle and neuronal glucose oxidation are proportional (1:1), with increasing neuronal activity above isoelectricity. GABA, a product of Glu metabolism, is synthesized from astroglial Gln and contributes to total Glu/Gln neurotransmitter cycling, although the fraction contributed by GABA is unknown. In the present study, we used13C NMR spectroscopy together with i.v. infusions of [1,6-13C2]glucose and [2-13C]acetate to separately determine rates of Glu/Gln and GABA/Gln cycling and their respective tricarboxylic acid cycles in the rat cortex under conditions of halothane anesthesia and pentobarbital-induced isoelectricity. Under 1% halothane anesthesia, GABA/Gln cycle flux comprised 23% of total (Glu plus GABA) neurotransmitter cycling and 18% of total neuronal tricarboxylic acid cycle flux. In isoelectric cortex, glucose oxidation was reduced >3-fold in glutamatergic and GABAergic neurons, and neurotransmitter cycling was below detection. Hence, in both cell types, the primary energetic costs are associated with neurotransmission, which increase together as cortical activity is increased. The contribution of GABAergic neurons and inhibition to cortical energy metabolism has broad implications for the interpretation of functional imaging signals.
Optical imaging of visually evoked responses in the middle temporal area after deactivation of primary visual cortex in adult primates
Authors: Collins Christine E. , Xu Xiangmin , Khaytin Ilya , Kaskan Peter M. , Casagrande Vivien A. , Kaas Jon H.
Published: April 2005

The middle temporal area (MT) is a visual area in primates with direct and indirect inputs from the primary visual cortex (V1), a role in visual motion perception, and a suggested role in “blindsight.” When V1 is deactivated, some studies report continued activation of MT neurons, which has been attributed to an indirect pathway to MT from the superior colliculus. Here we used muscimol to deactivate V1 while optically imaging visually evoked activity in MT in two primates, owl monkeys and galagos, where MT is exposed on the brain surface. The partial loss of V1 inputs abolished all or nearly all evoked activity in the retinotopically matched part of MT. Low levels of activation that persisted in portions of MT that were unstimulated or retinotopically congruent with the blocked portion of V1 appeared to reflect the spread of activity from stimulated to unstimulated parts of MT. Thus, a significant pathway based on the superior colliculus was not demonstrated.
Activity-dependent NMDA receptor degradation mediated by retrotranslocation and ubiquitination
Authors: Kato Akihiko , Rouach Nathalie , Nicoll Roger A. , Bredt David S.
Published: April 2005

The extracellular N-terminal domain (NTD) is the largest region of NMDA receptors; however, biological roles for this ectodomain remain unknown. Here, we determined that the F-box protein, Fbx2, bound to high-mannose glycans of the NR1 ectodomain. F-box proteins specify ubiquitination by linking protein substrates to the terminal E3 ligase. Indeed, ubiquitination of NR1 was increased by Fbx2 and diminished by an Fbx2 dominant-negative mutant. When expressed in hippocampal neurons, this Fbx2 dominant-negative mutant augmented NR1 subunit levels and NMDA receptor-mediated currents in an activity-dependent fashion. These results suggest that homeostatic control of synaptic NR1 involves receptor retrotranslocation and degradation by the ubiquitin-proteasome pathway.
Inhibition of NAD(P)H:quinone oxidoreductase 1 activity and induction of p53 degradation by the natural phenolic compound curcumin
Authors: Tsvetkov Peter , Asher Gad , Reiss Veronica , Shaul Yosef , Sachs Leo , Lotem Joseph
Published: April 2005

NAD(P)H:quinone oxidoreductase 1 (NQO1) regulates the stability of the tumor suppressor WT p53. NQO1 binds and stabilizes WT p53, whereas NQO1 inhibitors including dicoumarol and various other coumarins and flavones induce ubiquitin-independent proteasomal p53 degradation and thus inhibit p53-induced apoptosis. Here, we show that curcumin, a natural phenolic compound found in the spice turmeric, induced ubiquitin-independent degradation of WT p53 and inhibited p53-induced apoptosis in normal thymocytes and myeloid leukemic cells. Like dicoumarol, curcumin inhibited the activity of recombinant NQO1in vitro, inhibited the activity of endogenous cellular NQO1in vivo, and dissociated NQO1-WT p53 complexes. Neither dicoumarol nor curcumin dissociated the complexes of NQO1 and the human cancer hot-spot p53 R273H mutant and therefore did not induce degradation of this mutant. NQO1 knockdown by small-interfering RNA induced degradation of both WT p53 and the p53 R273H mutant. The results indicate that curcumin induces p53 degradation and inhibits p53-induced apoptosis by an NQO1-dependent pathway.
Single, context-specific glycans can target misfolded glycoproteins for ER-associated degradation
Authors: Spear Eric D. , Ng Davis T.W.
Published: April 2005

The endoplasmic reticulum (ER) maintains an environment essential for secretory protein folding. Consequently, the premature transport of polypeptides would be harmful to the cell. To avert this scenario, mechanisms collectively termed “ER quality control” prevent the transport of nascent polypeptides until they properly fold. Irreversibly misfolded molecules are sorted for disposal by the ER-associated degradation (ERAD) pathway. To better understand the relationship between quality control and ERAD, we studied a new misfolded variant of carboxypeptidase Y (CPY). The molecule was recognized and retained by ER quality control but failed to enter the ERAD pathway. Systematic analysis revealed that a single, specific N-linked glycan of CPY was required for sorting into the pathway. The determinant is dependent on the putative lectin-like receptor Htm1/Mnl1p. The discovery of a similar signal in misfolded proteinase A supported the generality of the mechanism. These studies show that specific signals embedded in glycoproteins can direct their degradation if they fail to fold.
Phosphatidylinositol-4,5-bisphosphate hydrolysis directs actin remodeling during phagocytosis
Authors: Scott Cameron C. , Dobson Wendy , Botelho Roberto J. , Coady-Osberg Natasha , Chavrier Philippe , Knecht David A. , Heath Colin , Stahl Philip , Grinstein Sergio
Published: April 2005

The Rho GTPases play a critical role in initiating actin polymerization during phagocytosis. In contrast, the factors directing the disassembly of F-actin required for fission of the phagocytic vacuole are ill defined. We used fluorescent chimeric proteins to monitor the dynamics of association of actin and active Cdc42 and Rac1 with the forming phagosome. Although actin was found to disappear from the base of the forming phagosome before sealing was complete, Rac1/Cdc42 activity persisted, suggesting that termination of GTPase activity is not the main determinant of actin disassembly. Furthermore, fully internalized phagosomes engineered to associate constitutively with active Rac1 showed little associated F-actin. The disappearance of phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) from the phagosomal membrane closely paralleled the course of actin disassembly. Furthermore, inhibition of PI(4,5)P2 hydrolysis or increased PI(4,5)P2 generation by overexpression of phosphatidylinositol phosphate kinase I prevented the actin disassembly necessary for the completion of phagocytosis. These observations suggest that hydrolysis of PI(4,5)P2 dictates the remodeling of actin necessary for completion of phagocytosis.
Phenylbutyrate up-regulates the adrenoleukodystrophy-related gene as a nonclassical peroxisome proliferator
Authors: Gondcaille Catherine , Depreter Marianne , Fourcade Stéphane , Lecca Maria Rita , Leclercq Sabrina , Martin Pascal G.P. , Pineau Thierry , Cadepond Françoise , ElEtr Martine , Bertrand Nathalie , Beley Alain , Duclos Sandrine , De Craemer Dirk , Roels Frank , Savary Stéphane , Bugaut Maurice
Published: April 2005

X-linked adrenoleukodystrophy (X-ALD) is a demyelinating disease due to mutations in the ABCD1 (ALD) gene, encoding a peroxisomal ATP-binding cassette transporter (ALDP). Overexpression of adrenoleukodystrophy-related protein, an ALDP homologue encoded by the ABCD2 (adrenoleukodystrophy-related) gene, can compensate for ALDP deficiency. 4-Phenylbutyrate (PBA) has been shown to induce both ABCD2 expression and peroxisome proliferation in human fibroblasts. We show that peroxisome proliferation with unusual shapes and clusters occurred in liver of PBA-treated rodents in a PPARα-independent way. PBA activated Abcd2 in cultured glial cells, making PBA a candidate drug for therapy of X-ALD. The Abcd2 induction observed was partially PPARα independent in hepatocytes and totally independent in fibroblasts. We demonstrate that a GC box and a CCAAT box of the Abcd2 promoter are the key elements of the PBA-dependent Abcd2 induction, histone deacetylase (HDAC)1 being recruited by the GC box. Thus, PBA is a nonclassical peroxisome proliferator inducing pleiotropic effects, including effects at the peroxisomal level mainly through HDAC inhibition.
E‐learning: what the literature tells us about distance education
Authors: Williams Pete , Nicholas David , Gunter Barrie
Published: April 2005

Purpose

The CIBER group at University College London are currently evaluating a distance education initiative funded by the Department of Health, providing in‐service training to NHS staff via DiTV and satellite to PC systems. This paper aims to provide the context for the project by outlining a short history of distance education, describing the media used in providing remote education, and to review research literature on achievement, attitude, barriers to learning and learner characteristics.

Design/methodology/approach

Literature review, with particular, although not exclusive, emphasis on health.

Findings

The literature shows little difference in achievement between distance and traditional learners, although using a variety of media, both to deliver pedagogic material and to facilitate communication, does seem to enhance learning. Similarly, attitudinal studies appear to show that the greater number of channels offered, the more positive students are about their experiences. With regard to barriers to completing courses, the main problems appear to be family or work obligations.

Research limitations/implications

The research work this review seeks to consider is examining “on‐demand” showing of filmed lectures via a DiTV system. The literature on DiTV applications research, however, is dominated by studies of simultaneous viewing by on‐site and remote students, rather than “on‐demand”.

Practical implications

Current research being carried out by the authors should enhance the findings accrued by the literature, by exploring the impact of “on‐demand” video material, delivered by DiTV – something no previous research appears to have examined.

Originality/value

Discusses different electronic systems and their exploitation for distance education, and cross‐references these with several aspects evaluated in the literature: achievement, attitude, barriers to take‐up or success, to provide a holistic picture hitherto missing from the literature.
Tackling student referencing errors through an online tutorial
Authors: Kendall Margaret
Published: April 2005

Purpose

To evaluate the impact of an interactive online tutorial aiming to improve student citing and referencing practice.

Design/methodology/approach

Action research involving three cycles of activity: identification of the most frequently occurring errors made by new undergraduates and postgraduates following instruction in citing and reference practice given in the autumn of 2002; creation of the tutorial for use by the same students in spring 2003, with the quizzes contributing to a portfolio assessment for the undergraduates. Comparison of the students’ performance before and after using the tutorial, monitoring through WebCT tracking facilities and usability tests with dyslexic students; adoption of the tutorial as the standard departmental practice, repeating the monitoring activities to compare the results with the previous year.

Findings

The results of the first cycle of activity showed a high number of errors, despite the instruction received by students, and the need to start the tutorial at an unanticipated basic level. The students responded positively to the tutorial and some improvements in practice were identified, although the tracking facilities revealed limited use by some undergraduates. Comparison of the errors made in 2003‐2004 with those of 2002‐2003 showed improvements all round.

Research limitations/implications

Some of the improvements may be accounted for by the change of practice part way through the previous academic year and other interventions.

Originality/value

The methods used will inform others wishing to carry out and evaluate online learning initiatives. It shows a qualified success in the use of online learning for this purpose.
Information management and e‐learning
Authors: Akeroyd John
Published: April 2005

Purpose

To provide a review of the interface between e‐learning, digital libraries and learning content.

Design/methodology/approach

A review of current thinking and activity surrounding the delivery of content in e‐learning systems. Some analysis of information concerns and commentary on future scenarios.

Findings

The paper investigates the reality of information management in e‐learning practice. It looks at types of information extant in systems and analyses links between (virtual) learning environments, digital libraries and web content. It examines the potential for reuse of material in a university context and the supporting standards and technology.

Research limitations/implications

Looks particularly at UK and US context but also has an international dimension.

Originality/value

It brings together a disposable set of issues to provide a discursive but practical summary of the topic. It will be of value to an information manager faced with managing content in a learning organisation.
Dominant supply chain co‐ordination strategies in the Dutch aerospace industry
Authors: Voordijk Hans , Meijboom Bert
Published: April 2005

Purpose

Firms in the aerospace industry face considerable pressure to improve co‐ordination in their supply chains. The major question of the present study is what supply chain co‐ordination strategies are dominant in the Dutch aerospace industry given the market environment of this industry?

Design/methodology/approach

Because information is the key ingredient for coordinating the supply chain in a given problem situation, an information processing point of view is adopted. In the empirical research, supply chain co‐ordination strategies are investigated for six Dutch‐based aerospace firms with different products and technologies.

Findings

It is concluded that in terms of the framework of Galbraith, co‐ordination strategies increasing the capacity to process information dominate supply chain management in the Dutch aerospace industry. The information‐processing capacity is increased by investing in lateral relations, long‐term planning and information systems between companies involved in the same supply chain.

Originality/value

Information is provided on Dutch aerospace firms' supply chain strategies.
Development of reaction wheels housing for micro‐satellites
Authors: Yeong Yong Sing , Chandrakant Joshi Sunil
Published: April 2005

Purpose

Nowadays, many micro‐satellites rely on three‐axis stabilization using at least three reaction wheels (RWs) for attitude control. Typically, RWs are mounted separately within the satellite and leads to long wires from each RW to the associated electronics. Placement and other constraints may also arise during integration. Furthermore, the large number of mounting holes required for mounting the RWs directly on the structural panels may weaken the integrity of the structure. This paper highlights a need for a special housing to be designed for mounting three to four RWs as a group at one location for simple and easy three‐axis stabilization of typical micro‐satellites.

Design/methodology/approach

Details about the development of the design methodology for such housing are discussed. The basic idea is to place the RWs onto the proposed housing, which will be then mounted on to one of the honeycomb panels used for the satellite structure. Requirements analysis, design, validation, and manufacturing process are covered.

Findings

The outcome is a dimensionally optimized housing structure for four RWs with a frequency safety factor of three.

Originality/value

In summary, the designed product satisfied all requirements. In addition, the exercise set out a planned procedure for designing similar housings for other satellite components.
Cutting temperature measurement while machining – a review
Authors: Longbottom J.M. , Lanham J.D.
Published: April 2005

Purpose

This paper gives the background to the measurement of metal cutting temperatures and a review of the practicality of the various methods of measuring cutting temperature while machining metals.

Design/methodology/approach

The review was compiled after a literature search, visits to other research establishments and discussions with other researchers in the machining/temperature measurement field.

Findings

Information about several methods of measuring cutting temperature during a machining process is given along with the limitations of the use of each method.

Practical implications

All the temperature measurement methods discussed have their limitations and these are described for each method listed.

Originality/value

The paper provides a review of all the cutting temperature measurement methods discovered in recent work. This will be a reference document of interest to others working in this field.
Food safety information and food demand
Authors: Smed Sinne , Dejgaard Jensen Jørgen
Published: April 2005

Purpose

The purpose of this paper is to analyze how news about food‐related health risks affects consumers’ demands for safe food products.

Design/methodology/approach

By identifying structural breaks in an econometrically estimated demand model, news with permanent impact on demand is distinguished from news with temporary impact. The Danish demand for pasteurized versus shell eggs is used as an illustrative case.

Findings

Negative safety news about one product variety can provide significant stimulation to the demand for safe varieties. Severe negative news about the safety of shell eggs induces a permanent increase in the demand for pasteurized eggs, while more moderate negative news influences demand temporarily and to a lesser extent. There is, however, considerable variation in the response to food safety news across socio‐demographic groups of consumers.

Research limitations/implications

The study has focused on the demand for raw eggs. Responses to food safety news may differ across foods. Furthermore, the study abstracts from possible cross‐effects of safety news concerning other foods.

Practical implications

The findings may be utilized for optimization of the timing and targeting of food safety information campaigns.

Originality/value

The paper combines information, food safety and econometric methods to analyze the cross‐impacts between negative food safety news and the demand for safe foods.
Creating a winning board: differing approaches of the boards of successful and struggling companies
Authors: Coulson‐Thomas Colin
Published: April 2005

Purpose

The article is intended to share findings from an ongoing investigation undertaken by questionnaire survey, interview and in‐company observation into the leadership of performance improvement and corporate transformation.

Design/methodology/approach

The article examines and compares the approaches and behaviours of winning and losing boards.

Findings

Directors and boards of companies that succeed at managing change, competing and winning exhibit very different approaches

Practical implications

Trainers and developers need to understand the differing approaches of the boards of successful and struggling companies and encourage and help directors, both individually and collectively, to learn from, emulate and develop the approaches and behaviours of those boards that are successful in managing change, competing and winning.

Originality/value

The article highlights behaviours and approaches that trainers and developers need to encourage if directors and boards are to become more effective at managing change, competing and winning.
Winston Churchill, a leader from history or an inspiration for the future?
Authors: Longstaffe Caroline
Published: April 2005

Purpose

In a world where the need for effective leadership has never been greater this article aims to: demonstrate that Sir Winston Churchill exemplified key leadership principles; that these principles are still relevant today; that Churchill remains a source of inspiration throughout the world to leaders both in business and politics; and that these principles are all behavioral and can be learnt by others.

Design/methodology/approach

The key leadership principles are identified. For each principle an examination is made of Churchill's behavior and how he exemplified each principle. Examples are also given from modern‐day leaders.

Findings

Churchill's leadership style demonstrates how his behaviour exemplifies key leadership principles which are still relevant today and can be used as a model for learning by others in order to become a more effective leader.

Originality/value

The paper is of value for anyone in any field that aspires to lead by demonstrating that leadership skills are about behaviour which can be learnt. The paper achieves this by examining the leadership principles Churchill exemplified showing how they are still relevant today.