bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonorthologous replacement of lysyl-tRNA synthetase prevents addition of lysine analogues to the genetic code
Authors: Jester Brian C. , Levengood Jeffrey D. , Roy Hervé , Ibba Michael , Devine Kevin M.
Published: November 2003

Insertion of lysine during protein synthesis depends on the enzyme lysyl-tRNA synthetase (LysRS), which exists in two unrelated forms, LysRS1 and LysRS2. LysRS1 has been found in most archaea and some bacteria, and LysRS2 has been found in eukarya, most bacteria, and a few archaea, but the two proteins are almost never found together in a single organism. Comparison of structures of LysRS1 and LysRS2 complexed with lysine suggested significant differences in their potential to bind lysine analogues with backbone replacements. One such naturally occurring compound, the metabolic intermediate
S
-(2-aminoethyl)-
l
-cysteine, is a bactericidal agent incorporated during protein synthesis via LysRS2.
In vitro
tests showed that
S
-(2-aminoethyl)-
l
-cysteine is a poor substrate for LysRS1, and that it inhibits LysRS1 200-fold less effectively than it inhibits LysRS2.
In vivo
inhibition by
S
-(2-aminoethyl)-
l
-cysteine was investigated by replacing the endogenous LysRS2 of
Bacillus subtilis
with LysRS1 from the Lyme disease pathogen
Borrelia burgdorferi. B. subtilis
strains producing LysRS1 alone were relatively insensitive to growth inhibition by
S
-(2-aminoethyl)-
l
-cysteine, whereas a WT strain or merodiploid strains producing both LysRS1 and LysRS2 showed significant growth inhibition under the same conditions. These growth effects arising from differences in amino acid recognition could contribute to the distribution of LysRS1 and LysRS2 in different organisms. More broadly, these data demonstrate how diversity of the aminoacyl-tRNA synthetases prevents infiltration of the genetic code by noncanonical amino acids, thereby providing a natural reservoir of potential antibiotic resistance.
The role of reactive oxygen species on
Plasmodium
melanotic encapsulation in
Anopheles gambiae
Authors: Kumar Sanjeev , Christophides George K. , Cantera Rafael , Charles Bradley , Han Yeon Soo , Meister Stephan , Dimopoulos George , Kafatos Fotis C. , Barillas-Mury Carolina
Published: November 2003

Malaria transmission depends on the competence of some
Anopheles
mosquitoes to sustain
Plasmodium
development (susceptibility). A genetically selected refractory strain of
Anopheles gambiae
blocks
Plasmodium
development, melanizing, and encapsulating the parasite in a reaction that begins with tyrosine oxidation, and involves three quantitative trait loci. Morphological and microarray mRNA expression analysis suggest that the refractory and susceptible strains have broad physiological differences, which are related to the production and detoxification of reactive oxygen species. Physiological studies corroborate that the refractory strain is in a chronic state of oxidative stress, which is exacerbated by blood feeding, resulting in increased steady-state levels of reactive oxygen species, which favor melanization of parasites as well as Sephadex beads.
Modeling facilitation and inhibition of competing motor programs in basal ganglia subthalamic nucleus–pallidal circuits
Authors: Rubchinsky Leonid L. , Kopell Nancy , Sigvardt Karen A.
Published: November 2003

The motor symptoms of Parkinson's disease (PD) implicate the basal ganglia (BG) in some aspect of motor control, although the role the BG play in regulation of motor behavior is not completely understood. The modeling study presented here takes advantage of available cellular, systems, and clinical data on BG and PD to begin to build a biophysically based network model of pallidosubthalamic circuits of BG, to integrate this information and better understand the physiology of the normal BG and PD pathophysiology. The model reflects the experimentally supported hypothesis that the BG are involved in facilitation of the desired motor program and inhibition of competing motor programs that interfere with the desired movement. Our model network consists of subthalamic and pallidal (both external and internal segments) neural assemblies, with inputs from cortex and striatum. Functional subsets within each of the BG nuclei correspond to the desired motor program and the unwanted motor programs. A single compartment conductance-based model represents each subset. This network can discriminate between competing signals for motor program initiation, thus facilitating a single motor program. This ability depends on metabotropic γ-aminobutyric acid B projections from the external pallidum to subthalamic nucleus and rebound properties of subthalamic cells, as well as on the structure of projections between pallidum and subthalamus. The loss of this ability leads to hypokinesia, known PD motor deficits characterized by a slowness or inability to switch between motor programs.
Atomistic understanding of kinetic pathways for single base-pair binding and unbinding in DNA
Authors: Hagan Michael F. , Dinner Aaron R. , Chandler David , Chakraborty Arup K.
Published: November 2003

We combine free-energy calculations and molecular dynamics to elucidate a mechanism for DNA base-pair binding and unbinding in atomic detail. Specifically, transition-path sampling is used to overcome computational limitations associated with conventional techniques to harvest many trajectories for the flipping of a terminal cytosine in a 3-bp oligomer in explicit water. Comparison with free-energy projections obtained with umbrella sampling reveals four coordinates that separate true dynamic transition states from stable reactant and product states. Unbinding proceeds via two qualitatively different pathways: one in which the flipping base breaks its intramolecular hydrogen bonds before it unstacks and another in which it ruptures both sets of interactions simultaneously. Both on- and off-pathway intermediates are observed. The relation of the results to coarse-grained models for DNA-based biosensors is discussed.
Drosophila Gr5a
encodes a taste receptor tuned to trehalose
Authors: Chyb Sylwester , Dahanukar Anupama , Wickens Andrew , Carlson John R.
Published: November 2003

Recent studies have suggested that
Drosophila
taste receptors are encoded by a family of G protein-coupled receptor genes comprising at least 56 members. One of these genes,
Gr5a
, has been shown by genetic analysis to be required by the fly for behavioral and sensory responses to a sugar, trehalose. Here, we show that
Gr5a
is expressed in neurons of taste sensilla located on the labellum and legs. Expression is observed in most if not all labellar sensilla and suggests that many taste neurons express more than one receptor. We demonstrate by heterologous expression in a
Drosophila
S2 cell line that
Gr5a
encodes a receptor tuned to trehalose. This is the first functional expression of an invertebrate taste receptor.
The construction of an EST database for
Bombyx mori
and its application
Authors: Mita Kazuei , Morimyo Mitsuoki , Okano Kazuhiro , Koike Yoshiko , Nohata Junko , Kawasaki Hideki , Kadono-Okuda Keiko , Yamamoto Kimiko , Suzuki Masataka G. , Shimada Toru , Goldsmith Marian R. , Maeda Susumu
Published: November 2003

To build a foundation for the complete genome analysis of
Bombyx mori
, we have constructed an EST database. Because gene expression patterns deeply depend on tissues as well as developmental stages, we analyzed many cDNA libraries prepared from various tissues and different developmental stages to cover the entire set of Bombyx genes. So far, the
Bombyx
EST database contains 35,000 ESTs from 36 cDNA libraries, which are grouped into ≈11,000 nonredundant ESTs with the average length of 1.25 kb. The comparison with FlyBase suggests that the present EST database, SilkBase, covers >55% of all genes of
Bombyx
. The fraction of library-specific ESTs in each cDNA library indicates that we have not yet reached saturation, showing the validity of our strategy for constructing an EST database to cover all genes. To tackle the coming saturation problem, we have checked two methods, subtraction and normalization, to increase coverage and decrease the number of housekeeping genes, resulting in a 5–11% increase of library-specific ESTs. The identification of a number of genes and comprehensive cloning of gene families have already emerged from the SilkBase search. Direct links of SilkBase with FlyBase and WormBase provide ready identification of candidate Lepidoptera-specific genes.
The isoniazid-NAD adduct is a slow, tight-binding inhibitor of InhA, the
Mycobacterium tuberculosis
enoyl reductase: Adduct affinity and drug resistance
Authors: Rawat Richa , Whitty Adrian , Tonge Peter J.
Published: November 2003

Isoniazid (INH), a frontline antitubercular drug, inhibits InhA, the enoyl reductase from
Mycobacterium tuberculosis
, by forming a covalent adduct with the NAD cofactor. Here, we report that the INH-NAD adduct is a slow, tight-binding competitive inhibitor of InhA. Demonstration that the adduct binds to WT InhA by a two-step enzyme inhibition mechanism, with initial, weak binding (
K
–1
= 16 ± 11 nM) followed by slow conversion to a final inhibited complex (EI*) with overall
K
i
= 0.75 ± 0.08 nM, reconciles existing contradictory values for the inhibitory potency of INH-NAD for InhA. The first order rate constant for conversion of the initial EI complex to EI* (
k
2
= 0.13 ± 0.01 min
–1
) is similar to the maximum rate constant observed for InhA inhibition in reaction mixtures containing InhA, INH, NADH, and the INH-activating enzyme KatG (catalase/peroxidase from
M. tuberculosis
), consistent with an inhibition mechanism in which the adduct forms in solution rather than on the enzyme. Importantly, three mutations that correlate with INH resistance, I21V, I47T, and S94A, have little impact on the inhibition constants. Thus, drug resistance does not result simply from a reduction in affinity of INH-NAD for pure InhA. Instead, we hypothesize that protein–protein interactions within the FASII complex are critical to the mechanism of INH action. Finally, for M161V, an InhA mutation that correlates with resistance to the common biocide triclosan in
Mycobacterium smegmatis
, binding to form the initial EI complex is significantly weakened, explaining why this mutant inactivates more slowly than WT InhA when incubated with INH, NADH, and KatG.
Locking the DNA topoisomerase I protein clamp inhibits DNA rotation and induces cell lethality
Authors: Woo Michael H. , Losasso Carmen , Guo Hong , Pattarello Luca , Benedetti Piero , Bjornsti Mary-Ann
Published: November 2003

Eukaryotic DNA topoisomerase I (Top1) is a monomeric protein clamp that functions in DNA replication, transcription, and recombination. Opposable “lip” domains form a salt bridge to complete Top1 protein clamping of duplex DNA. Changes in DNA topology are catalyzed by the formation of a transient phosphotyrosyl linkage between the active-site Tyr-723 and a single DNA strand. Substantial protein domain movements are required for DNA binding, whereas the tight packing of DNA within the covalent Top1–DNA complex necessitates some DNA distortion to allow rotation. To investigate the effects of Top1-clamp closure on enzyme catalysis, molecular modeling was used to design a disulfide bond between residues Gly-365 and Ser-534, to crosslink protein loops more proximal to the active-site tyrosine than the protein loops held by the Lys-369–Glu-497 salt bridge. In reducing environments, Top1-Clamp was catalytically active. However, contrary to crosslinking the salt-bridge loops [Carey, J. F., Schultz, S. J., Sission, L., Fazzio, T. G. & Champoux, J. J. (2003)Proc. Natl. Acad. Sci. USA100, 5640–5645], crosslinking the active-site proximal loops inhibited DNA rotation. Apparently, subtle alterations in Top1 clamp flexibility impact enzyme catalysisin vitro. Yet, the catalytically active Top1-Clamp was cytotoxic, even in the reducing environment of yeast cells. Remarkably, a shift in redox potential inglr1Δ cells converted the catalytically inactive Top1Y723F mutant clamp into a cellular toxin, which failed to induce an S-phase terminal phenotype. This cytotoxic mechanism is distinct from that of camptothecin chemotherapeutics, which stabilize covalent Top1–DNA complexes, and it suggests that the development of novel therapeutics that promote Top1-clamp closure is possible.
Haploinsufficiency of Anx7 tumor suppressor gene and consequent genomic instability promotes tumorigenesis in the Anx7(+/-) mouse
Authors: Srivastava Meera , Montagna Cristina , Leighton Ximena , Glasman Mirta , Naga Shanmugam , Eidelman Ofer , Ried Thomas , Pollard Harvey B.
Published: November 2003

Annexin 7 (ANX7) acts as a tumor suppressor gene in prostate cancer, where loss of heterozygosity and reduction of ANX7 protein expression is associated with aggressive metastatic tumors. To investigate the mechanism by which this gene controls tumor development, we have developed an
Anx7
(+/-) knockout mouse. As hypothesized, the
Anx7
(+/-) mouse has a cancer-prone phenotype. The emerging tumors express low levels of Anx7 protein. Nonetheless, the wild-type
Anx7
allele is detectable in laser-capture microdissection-derived tumor tissue cells. Genome array analysis of hepatocellular carcinoma tissue indicates that the Anx7(+/-) genotype is accompanied by profound reductions of expression of several other tumor suppressor genes, DNA repair genes, and apoptosis-related genes.
In situ
analysis by tissue imprinting from chromosomes in the primary tumor and spectral karyotyping analysis of derived cell lines identify chromosomal instability and clonal chromosomal aberrations. Furthermore, whereas 23% of the mutant mice develop spontaneous neoplasms, all mice exhibit growth anomalies, including gender-specific gigantism and organomegaly. We conclude that haploinsufficiency of
Anx7
expression appears to drive disease progression to cancer because of genomic instability through a discrete signaling pathway involving other tumor suppressor genes, DNA-repair genes, and apoptosis-related genes.
Forest fragmentation severs mutualism between seed dispersers and an endemic African tree
Authors: Cordeiro Norbert J. , Howe Henry F.
Published: November 2003

Because bird species are lost when forests are fragmented into small parcels, trees that depend on fruit-eating birds for seed dispersal may fail to recruit seedlings if dispersal agents disappear. We tested this prediction in rainforest in the East Usambara Mountains of Tanzania, by using the endemic tree
Leptonychia usambarensis
(Sterculiaceae) and birds that disperse its seeds. We investigated bird abundance and
Leptonychia
dispersal ecology in fragments isolated for >70 yr, as compared with 3,500 ha of continuous forest. Birds that dispersed
Leptonychia
seeds in continuous forest were rare or absent in small fragments, where fewer seeds were removed from each tree, far fewer seedlings occurred >10 m from parent trees, and far more seedlings occurred in dense aggregations under parental crowns. Overall, our samples showed that fewer juvenile
Leptonychia
recruited in fragments than in continuous forest. We provide solid evidence that deficient dispersal due to habitat fragmentation seriously impacts the reproductive cycle of a tropical bird-dispersed tree.
Divergent selection during speciation of Lake Malawi cichlid fishes inferred from parallel radiations in nuptial coloration
Authors: Allender Charlotte J. , Seehausen Ole , Knight Mairi E. , Turner George F. , Maclean Norman
Published: November 2003

Repeated evolution of the same phenotypic difference during independent episodes of speciation is strong evidence for selection during speciation. More than 1,000 species of cichlids, >10% of the world's freshwater fish species, have arisen within the past million years in Lakes Malawi and Victoria in eastern Africa. Many pairs of closely related sympatric species differ in their nuptial coloration in very similar ways. Nuptial coloration is important in their mate choice, and speciation by sexual selection on genetically or ecologically constrained variation in nuptial coloration had been proposed, which would repeatedly produce similar nuptial types in different populations, a prediction that was difficult to test in the absence of population-level phylogenies. We measured genetic similarity between individuals within and between populations, species, and lake regions by typing 59 individuals at >2,000 polymorphic genetic loci. From these data, we reconstructed, to our knowledge, the first larger species level phylogeny for the most diverse group of Lake Malawi cichlids. We used the genetic and phylogenetic data to test the divergent selection scenario against colonization, character displacement, and hybridization scenarios that could also explain diverse communities. Diversity has arisen by replicated radiations into the same color types, resulting in phenotypically very different, yet closely related, species within and phenotypically highly similar yet unrelated sets of species between regions, which is consistent with divergent selection during speciation and is inconsistent with colonization and character displacement models.
Functional profiling of a human cytomegalovirus genome
Authors: Dunn Walter , Chou Cassie , Li Hong , Hai Rong , Patterson David , Stolc Viktor , Zhu Hua , Liu Fenyong
Published: November 2003

Human cytomegalovirus (HCMV), a ubiquitous herpesvirus, causes a lifelong subclinical infection in healthy adults but leads to significant morbidity and mortality in neonates and immunocompromised individuals. Its ability to grow in different cell types is responsible for HCMV-associated diseases, including mental retardation and retinitis, and vascular disorders. To globally assess viral gene function for replication in cells, we determined the genomic sequence of a bacterial artificial chromosome (BAC)-based clone of HCMV Towne strain and used this information to delete each of its 162 unique ORFs and generate a collection of viral mutants. The growth of these mutants in different cultured cells was examined to systematically investigate the necessity of each ORF for replication. Our results showed that 45 ORFs are essential for viral replication in fibroblasts and 117 are nonessential. Some genes were found to be required for viral replication in retinal pigment epithelial cells and microvascular endothelial cells, but not in fibroblasts, indicating their role as tropism factors. Interestingly, several viral mutants grew 10- to 500-fold better than the parental strain in different cell types, suggesting that the deleted ORFs encode replication temperance or repressing functions. Thus, HCMV encodes supportive and suppressive growth regulators for optimizing its replication in human fibroblasts, epithelial, and endothelial cells. Suppression of viral replication by virus-encoded temperance factors represents a novel mechanism for regulating the growth of an animal virus, and may contribute to HCMV's optimal infection of different tissues and successful proliferation among the human population.
The glycine neurotransmitter transporter GLYT1 is an organic osmolyte transporter regulating cell volume in cleavage-stage embryos
Authors: Steeves Candace L. , Hammer Mary-Anne , Walker Glenn B. , Rae Duncan , Stewart Nicolas A. , Baltz Jay M.
Published: November 2003

Cells subjected to sustained high osmolarity almost universally respond by accumulating compatible organic osmolytes that, in contrast to inorganic ions, are not deleterious even at high intracellular concentrations. Their accumulation from the external environment by known organic osmolyte transporters, such as the four identified in mammals, occurs only slowly in response to sustained high osmolarity, by synthesis of new transporter proteins. Most cells, however, are not subject to high or varying osmolarity, and it is not clear whether organic osmolytes are generally required at normal osmolarities or how they are regulated. The fertilized egg of the mouse is protected in the oviduct from perturbations in osmolarity. However, deleterious effects of osmotic stress were evidentin vitroeven at normal oviductal osmolarity. Glycine was found to protect development, indicating that early mouse embryos may use glycine as an organic osmolyte at physiological osmolarity. We have now found that GLYT1, a glycine transporter of the neurotransmitter transporter gene family, functions as the organic osmolyte transporter that mediates the osmotically regulated accumulation of glycine and regulates cell volume in early embryos. Furthermore, osmotic stimulation of GLYT1 transport was immediate, without a requirement for protein synthesis, implying regulation different from known organic osmolyte transporters. Thus, GLYT1 appears to have a previously unidentified role as an organic osmolyte transporter that functions in acute organic osmolyte and volume homeostasis near normal osmolarity.
The laminin receptor modulates granulocyte–macrophage colony-stimulating factor receptor complex formation and modulates its signaling
Authors: Chen Jian , Cárcamo Juan M. , Bórquez-Ojeda Oriana , Erdjument-Bromage Hediye , Tempst Paul , Golde David W.
Published: November 2003

Basement membrane matrix proteins are known to up-regulate granulocyte–macrophage colony-stimulating factor (GM-CSF) signaling in neutrophils and mononuclear phagocytes, but the mechanisms involved are poorly understood. We used the intracellular portion of the α subunit of the GM-CSF receptor (αGMR) to search for interacting proteins and identified the 67-kDa laminin receptor (LR), a nonintegrin matrix protein receptor expressed in several types of host defense cells and certain tumors, as a binding partner. LR was found to interact with the β subunit of the GMR (βGMR) as well. Whereas GM-CSF functions by engaging the αGMR and βGMR into receptor complexes, LR inhibited GM-CSF-induced receptor complex formation. Laminin and fibronectin binding to LR was found to prevent the binding of βGMR to LR and relieved the LR inhibition of GMR. These findings provide a mechanistic basis for enhancing host defense cell responsiveness to GM-CSF at transendothelial migration sites while suppressing it in circulation.
The
Vibrio cholerae
O139 O-antigen polysaccharide is essential for Ca
2+
-dependent biofilm development in sea water
Authors: Kierek Katharine , Watnick Paula I.
Published: November 2003

Vibrio cholerae
is both an inhabitant of estuarine environments and the etiologic agent of the diarrheal disease cholera. Previous work has demonstrated that
V. cholerae
forms both an exopolysaccharide-dependent biofilm and a Ca
2+
-dependent biofilm. In this work, we demonstrate a role for the O-antigen polysaccharide of
V. cholerae
in Ca
2+
-dependent biofilm development in model and true sea water. Interestingly,
V. cholerae
biofilms, as well as the biofilms of several other
Vibrio
species, disintegrate when Ca
2+
is removed from the bathing medium, suggesting that Ca
2+
is interacting directly with the O-antigen polysaccharide. In the Bay of Bengal, cholera incidence has been correlated with increased sea surface height. Because of the low altitude of this region, increases in sea surface height are likely to lead to transport of sea water, marine particulates, and marine biofilms into fresh water environments. Because fresh water is Ca
2+
-poor, our results suggest that one potential outcome of an increase is sea surface height is the dispersal of marine biofilms with an attendant increase in planktonic marine bacteria such as
V. cholerae
. Such a phenomenon may contribute to the correlation of increased sea surface height with cholera.
Nuclear translocation of 3′-phosphoinositide-dependent protein kinase 1 (PDK-1): A potential regulatory mechanism for PDK-1 function
Authors: Lim Mei A. , Kikani Chintan K. , Wick Michael J. , Dong Lily Q.
Published: November 2003

3′-Phosphoinositide-dependent protein kinase 1 (PDK-1) phosphorylates and activates members of the AGC protein kinase family and plays an important role in the regulation of cell survival, differentiation, and proliferation. However, how PDK-1 is regulated in cells remains elusive. In this study, we demonstrated that PDK-1 can shuttle between the cytoplasm and nucleus. Treatment of cells with leptomycin B, a nuclear export inhibitor, results in a nuclear accumulation of PDK-1. PDK-1 nuclear localization is increased by insulin, and this process is inhibited by pretreatment of cells with phosphatidylinositol 3-kinase (PI3-kinase) inhibitors. Consistent with the idea that PDK-1 nuclear translocation is regulated by the PI3-kinase signaling pathway, PDK-1 nuclear localization is increased in cells deficient of PTEN (phosphatase and tensin homologue deleted on chromosome 10). Deletion mapping and mutagenesis studies unveiled that presence of a functional nuclear export signal (NES) in mouse PDK-1 located at amino acid residues 382 to 391. Overexpression of constitutively nuclear PDK-1, which retained autophosphorylation at Ser-244 in the activation loop in cells and its kinase activity
in vitro
, led to increased phosphorylation of the predominantly nuclear PDK-1 substrate p70 S6KβI. However, the ability of constitutively nuclear PDK-1 to induce anchorage-independent growth and to protect against UV-induced apoptosis is greatly diminished compared with the wild-type enzyme. Taken together, these findings suggest that nuclear translocation may be a mechanism to sequestrate PDK-1 from activation of the cytosolic signaling pathways and that this process may play an important role in regulating PDK-1-mediated cell signaling and function.
Crystal structure of a hydrophobic 19-residue peptide helix containing three centrally located
d
amino acids
Authors: Karle Isabella L. , Gopi Hosahudya N. , Balaram Padmanabhan
Published: November 2003

The design of the synthetic 19-residue peptide Boc-Leu-Aib-Val-Ala-Leu
5
-Aib-Val-
d
-Ala
-
d
-Leu-Leu
10
-Val-Phe-Val-Aib-
d
-Val
15
-Leu-Phe-Val-Val-OMe (Aib, α-aminoisobutyric acid; OMe, methyl ester) was intended to produce a crystalline peptide with independent helical and hairpin domains. The design was partially based on an octapeptide with the same sequence as residues 11–18 above, which was shown to fold into a β-hairpin in the crystal. However, the crystal structure of the present peptide provided a surprising result. The conformation is the longest characterized right-handed α-helix, with as many as three internal
d
residues in the sequence. The completely helical structure was also unexpected, because β-branched residues such as Val have a low propensity for helix formation in proteins. The helical peptides in the present structure assemble to form hydrophobic channels that accommodate five toluene molecules per peptide along the length of the channel. The structural results illustrate the similarity in energetics between helical and β-hairpin conformations for peptides containing Aib residues. The crystallographic parameters for C
107
H
179
N
19
O
22
·3H
2
O·2.5 toluenes are: space group C2,
a
= 34.679(3) Å,
b
= 12.866(1) Å,
c
= 31.915(3) Å, β = 96.511(8)°,
V
= 14,148 Å
3
,
Z
= 4,
d
calc
= 1.099 g/cm
3
, and agreement factor
R
1
= 10.2%.
Human adipocytes secrete mineralocorticoid-releasing factors
Authors: Ehrhart-Bornstein M. , Lamounier-Zepter V. , Schraven A. , Langenbach J. , Willenberg H. S. , Barthel A. , Hauner H. , McCann S. M. , Scherbaum W. A. , Bornstein S. R.
Published: November 2003

Obesity has become an epidemic problem in western societies, contributing to metabolic diseases, hypertension, and cardiovascular disease. Overweight and obesity are frequently associated with increased plasma levels of aldosterone. Recent evidence suggests that human fat is a highly active endocrine tissue. Therefore, we tested the hypothesis that adipocyte secretory products directly stimulate adrenocortical aldosterone secretion. Secretory products from isolated human adipocytes strongly stimulated steroidogenesis in human adrenocortical cells (NCI-H295R) with a predominant effect on mineralocorticoid secretion. Aldosterone secretion increased 7-fold during 24 h of incubation. This stimulation was comparable to maximal stimulation of these cells with forskolin (2 × 10
–5
M). On the molecular level, there was a 10-fold increase in the expression of steroid acute regulatory peptide mRNA. This effect was independent of adipose angiotensin II as revealed by the stimulatory effect of fat cell-conditioned medium even in the presence of the angiotensin type 1 receptor antagonist, valsartan. None of the recently defined adipocytokines accounted for the effect. Mineralocorticoid-stimulating activity was heat sensitive and could be blunted by heating fat cell-conditioned medium to 99°C. Centrifugal filtration based on molecular mass revealed at least two releasing factors: a heat sensitive fraction (molecular mass >50 kDa) representing 60% of total activity, and an inactive fraction (molecular mass <50 kDa). However, the recovery rate increased to 92% when combining these two fractions, indicating the interaction of at least two factors. In conclusion, human adipocytes secrete potent mineralocorticoid-releasing factors, suggesting a direct link between obesity and hypertension.
TPPP/p25 promotes tubulin assemblies and blocks mitotic spindle formation
Authors: Tirián L. , Hlavanda E. , Oláh J. , Horváth I. , Orosz F. , Szabó B. , Kovács J. , Szabad J. , Ovádi J.
Published: November 2003

Recently, we isolated from bovine brain a protein, TPPP/p25 and identified as p25, a brain-specific protein that induced aberrant tubulin assemblies. The primary sequence of this protein differs from that of other proteins identified so far; however, it shows high homology with p25-like hypothetical proteins sought via
blast
. Here, we characterized the binding of TPPP/p25 to tubulin by means of surface plasmon resonance; the kinetic parameters are as follows:
k
on
, 2.4 × 10
4
M
–1
·s
–1
;
k
off
, 5.4 × 10
–3
s
–1
; and
K
d
, 2.3 × 10
–7
M. This protein at substoichometric concentration promotes the polymerization of tubulin into double-walled tubules and polymorphic aggregates or bundles paclitaxel-stabilized microtubules as judged by quantitative data of electron and atomic force microscopies. Injection of bovine TPPP/p25 into cleavage
Drosophila
embryos expressing tubulin–GFP fusion protein reveals that TPPP/p25 inhibits mitotic spindle assembly and nuclear envelope breakdown without affecting other cellular events like centrosome replication and separation, microtubule nucleation by the centrosomes, and nuclear growth. GTP counteracts TPPP/p25 both
in vitro
and
in vivo
.
Computational mathematics and physics of fusion reactors
Authors: Garabedian Paul R.
Published: November 2003

Theory has contributed significantly to recent advances in magnetic fusion research. New configurations have been found for a stellarator experiment by computational methods. Solutions of a free-boundary problem are applied to study the performance of the plasma and look for islands in the magnetic surfaces. Mathematical analysis and numerical calculations have been used to study equilibrium, stability, and transport of optimized fusion reactors.
The influence of soil heterogeneity on exploratory tunnelling by the subterranean termite Coptotermes frenchi (Isoptera: Rhinotermitidae)
Authors: Evans T.A.
Published: November 2003

The exploration of sand-filled arenas by workers of an entire colony of the Australian, subterranean foraging, tree-nesting termite, Coptotermes frenchi Hill was investigated under laboratory conditions. The first experiment tested whether termite exploration of sand was influenced by the presence of gaps or objects in the sand. Gaps and objects were chosen to represent soil heterogeneity in the urban environment: gaps to represent tunnels dug by other animals, perspex strips to represent cables and pipes, and wood strips to represent roots. Termites always chose to explore gaps thoroughly before they began tunnelling in the sand. Significantly more and longer tunnels were excavated from the end of gaps at the far end of the arenas, and relatively little tunnelling occurred around and along objects. Termite density was significantly greater around and along wood compared with perspex blocks. The second experiment tested whether termite exploratory tunnelling was influenced by soil moisture. The termites tunnelled slowly in dry sand, but after discovering a patch of wet sand, increased tunnelling five-fold until it was completely explored, after which activity declined. Energy and water conservation may be behind these patterns of exploratory tunnelling as well as those seen in large field studies, but caution is urged when interpreting small scale laboratory experiments to explain large scale field data.
Termite colony ontogeny: a long-term assessment of reproductive lifespan, caste ratios and colony size in Reticulitermes flavipes (Isoptera: Rhinotermitidae)
Authors: Long C.E. , Thorne B.L. , Breisch N.L.
Published: November 2003

Thirty Reticulitermes flavipes (Kollar) colonies established by alates collected from two separate field sites were raised in the laboratory for eight years. Twenty-one of the colonies were founded by alates from one field source and nine from another, providing demographic data from two unrelated parental lineages. Colony totals ranged from 3620 to 11641 individuals, with no significant difference in size between lineages. Soldier caste proportion of the colony total and mean wet weights for workers, soldiers and kings were significantly different between the two lineages. This suggests that at least a portion of the variability observed in caste ratios and body size may be heritable. One founding reproductive had died in five of the colonies (17%); none lost both parents. The queenless colonies contained exclusively female replacement reproductives (neotenics); the kingless colony contained a female-skewed mixture of male and female neotenics. All the nests that lost a founding parent contained significantly more pre-alate nymphs than the nests with both a king and a queen. Comparisons with published reports of ontogenetic patterns in other termites and social insects are discussed.
Characterization of a dual plant protein kinase (FsPK1) up-regulated by abscisic acid and calcium and specifically expressed in dormant seeds ofFagus sylvaticaL.
Authors: Lorenzo O. , Nicolás C. , Nicolás G. , Rodríguez D.
Published: November 2003

An abscisic acid (ABA)-induced cDNA fragment encoding a putative protein kinase (PK) was obtained by differential screening of a cDNA library fromFagus sylvaticaseeds. The full-length clone, named FsPK1, was produced by 5′ rapid amplification of cDNA ends (RACE) extension. This clone contained the 11 catalytic domains present in all protein kinases, but displayed unusual characteristics found only in a few plant PKs. FsPK1 exhibits features of both serine/threonine and tyrosine protein kinases within the catalytic domain, a putative nuclear localization signal within the regulatory domain and the consensus sequence involved in binding of 14-3-3 proteins. The catalytic domain, expressed inEscherichia colias a fusion protein, showed Ca2+-dependentin vitrokinase activity and dual serine/threonine and tyrosine specificity. Transcription of theFsPK1gene was reduced by seed stratification at 4°C, and clearly increased when seeds were treated with 0.1 mM ABA, correlating with the inhibition of germination. Interestingly,FsPK1transcripts were enhanced when ABA (0.1 mM) and calcium (1 mM) were added together, while the addition of EGTA (calcium chelator) and 3,4,5,-trimethoxibenzoic acid 8-(diethylamino) octyl ester (TMB-8, a calcium antagonist) decreased its expression. Furthermore,FsPK1transcript expression was tissue specific and accumulated only in ABA-treated seeds, but not in any ABA-treated vegetative tissues examined. These results suggest that the expression of the corresponding protein could be related to the inhibition of germination mediated by ABA in a calcium-dependent pathway.
Artists, Aestheticisation and the Field of Gentrification
Authors: Ley David
Published: November 2003

Gentrification involves the transition of inner-city neighbourhoods from a status of relative poverty and limited property investment to a state of commodification and reinvestment. This paper reconsiders the role of artists as agents, and aestheticisation as a process, in contributing to gentrification, an argument illustrated with empirical data from Toronto, Montreal and Vancouver. Because some poverty neighbourhoods may be candidates for occupation by artists, who value their afford ability and mundane, off-centre status, the study also considers the movement of districts from a position of high cultural capital and low economic capital to a position of steadily rising economic capital. The paper makes extensive use of Bourdieu's conceptualisation of the field of cultural production, including his discussion of the uneasy relations of economic and cultural capitals, the power of the aesthetic disposition to valorise the mundane and the appropriation of cultural capital by market forces. Bourdieu's thinking is extended to the field of gentrification in an account that interprets the enhanced valuation of cultural capital since the 1960s, encouraging spatial proximity by other professionals to the inner-city habitus of the artist. This approach offers some reconciliation to theoretical debates in the gentrification literature about the roles of structure and agency and economic and cultural explanations. It also casts a more critical historical perspective on current writing lauding the rise of the cultural economy and the creative city.
Temporal Characterization of a Plasma Produced by Interaction of Laser Pulses with Water Solutions
Authors: Ben Ahmed J. , Terzi N. , Ben Lakhdar Z. , Taieb G.
Published: November 2003

The temporal evolution of a plasma formed by the interaction of a Nd‐YAG 10 ns laser
pulse with the surface of aqueous solutions of CaCl2, has been observed by analyzing the
variation of the emission spectra of ions and neutral atoms in the time interval after the
laser pulse, 500 ns < t < 5000 ns. The intensity measurements of the lines of CaII at
3158 Å, 3179 Å, 3706 Å, 3736 Å, 3933 Å, 3968 Å were used to obtain the electronic
temperature Te using a Saha‐Boltzmann analysis. The broadening of the resonance line
of CaI at 4227 Å was used to deduce the electronic density Ne, with the aid of the semiclassical
theory of Stark broadening. A value of Te ≈ 28000 K decreasing slightly to
21000 K, and an exponential decay for Ne were found, with Ne ≈ 1:25 × 1018 cm-3 at 500 ns and τe = (1200 ± 50) ns.
Globalization of Japanese culture: Economic power vs. cultural power, 1989-2002
Authors: Yong jin Dal
Published: November 2003

This article examines the reasons why Japanese cultural products have not penetrated other countries. It also explicates the recent trends in Japan's expansion of its cultural products and Japan's direct investment in the global cultural market to ascertain whether this new development is a sign that Japan is attempting to gain an important role in global communication. It concludes that Japan was not able to successfully build its communication power to a degree comparable to its status as the second largest economic power and its second largest media consumption market.
R&D in the United States department of homeland security
Authors: Koizumi Kei , Carney Joanne , Cooper David , Teich Al
Published: November 2003

” The Department of Homeland Security (DHS) began full operations in March by consolidating nearly 180,000 federal employees from nearly two-dozen agencies into a single cabinet-level department . ” The DHS would become one of the major funding sources of R&D . The DHS R&D portfolio would total $1.0 billion in FY 2004, a 50% jump from the $669 million for comparable programs in FY 2003 and nearly quadruple the FY 2002 funding level . 2 ” In FY 2003, DHS R&D would be mostly transfers of existing programs from the Departments of Agriculture (USDA), Defense (DOD), Energy (DOE), and Transportation (DOT), but in FY 2004 a new Homeland Security Advanced Research Projects Agency (HSARPA) would fund extramural R&D. ” Bioterrorism R&D would stay in the National Institutes of Health (NIH), but DHS will have a priority-setting role .
Naltrexone in the treatment of male alcoholics—an effectiveness study in Singapore
Authors: LEE ARTHUR , TAN SHAWN , LIM DOMINIC , WINSLOW R. M. , WONG K. E. , ALLEN JOHN , HALL WAYNE , PARKER GORDON
Published: November 2003

Naltrexone has been demonstrated in western studies to be a useful pharmacological adjunct within treatment programmes for alcoholic patients. We report the first study of its efficacy and usefulness in an Asian region. This project was designed to allow naltrexone's performance to be assessed under routine clinical conditions but with patients selected on the basis of their being likely to comply. Following in‐patient detoxification, 53 male alcohol‐dependent patients admitted to the Alcohol Treatment Centre at Woodbridge Hospital, Singapore, were enrolled in a 12‐week, placebo‐controlled trial of naltrexone hydrochloride (50 mg/day). Subjects were randomized on a 2:1 basis, with 35 receiving naltrexone and 18 receiving placebo. Analyses identified that a higher percentage of naltrexone patients completed the study (40% vs. 22%). In the study non‐completers, the dropout rate due to drinking relapse was also lower in the naltrexone group (9% vs. 43%). Of the 39 patients for whom drinking status over the trial could be ascertained, fewer naltrexone‐treated patients drank (33% vs. 53%). Alcohol craving scores also showed a selective and distinct reduction in the naltrexone‐treated group. Results suggest that naltrexone may be an effective and safe aid to treatment of alcohol dependent patients in Asian patients, for whom the aims are to reduce alcohol craving and drinking reinstatement, but where compliance is likely to be low.
Police knowledge and attitudes regarding crime, the responsible service of alcohol and a proactive alcohol policing strategy
Authors: SMITH KYLIE L. , WIGGERS JOHN H. , CONSIDINE ROBYN J. , DALY JUSTINE B. , COLLINS TERRY
Published: November 2003

The purpose of this study was to investigate the pattern and predictors of police knowledge and attitudes regarding alcohol and crime, the responsible service of alcohol by licensees and proactive alcohol policing strategies. Operational police in the Hunter region of NSW, Australia who attended for duty on a selected weekday were invited to complete a questionnaire during their shift. Two hundred and ninety‐eight police participated (77%). Police estimated that 60% of the incidents that they attend are related to the consumption of alcohol, with 44% of such incidents relating to alcohol consumed on licensed premises. Three‐quarters of police were able to identify correctly responsible service components of the Liquor Act. A large proportion of police (93%) considered that alcohol servers are responsible for preventing intoxication and that trying to improve licensee serving practices is not a waste of police time (89%). Considerable support (67%) was shown for police using education rather than enforcement as a method for improving licensee responsible service practices. Strong support (92%) was shown for providing information to licensees about alcohol‐related incidents associated with their premises. Only 55% of police reported having sufficient skills and 17% reported that sufficient police resources were used to enhance licensee alcohol service practices. The introduction of liquor legislation, with an explicit “responsible service of alcohol” emphasis, provides police with considerable opportunity to improve the serving practices of licensed premises and to reduce alcohol‐related harm. The perception by police of a lack of skill, a low prioritization for alcohol policing, limited time availability and inadequate penalties may prevent the realization of these benefits. Enhanced police training and the development of alternative responsible service of alcohol policing strategies are needed if these benefits are to be achieved.
Injury and alcohol: a hospital emergency department study
Authors: ROCHE ANN M. , WATT KERRIANNE , McCLURE ROD , PURDIE DAVID M. , GREEN DAVID
Published: November 2003

A pilot survey was undertaken of injury presentations to a public hospital emergency department to determine patterns of alcohol use in this population. Of the 402 injury presentations in the study period, a total of 236 injury cases were interviewed, of whom 45% (n = 107) and 29% (n = 69) had consumed alcohol 24 and 6 hours prior to injury. Mean age for all injury presentations was 35.1 years, and 32.6 years for alcohol injury cases. For both injury groups, males were significantly younger than females. Recent alcohol ingestion was three times more common among male than female injury presentations, but with females drinking at significantly lower levels. Of males who had consumed alcohol 6 hours prior to injury, nearly 70% were drinking at NHMRC harmful levels and 61% had drunk more than eight standard drinks. Overall, alcohol‐involved injury cases commonly occurred among low‐income, single males around 30 years of age who were regular heavy drinkers who were drinking heavily in licensed premises prior to their injury, and who sustained injury through intentional harm. In addition, one in five of the alcohol‐involved injury cases were aged 15–18 years, i.e. below the legal age of purchase. The high proportion of hazardous and harmful drinkers among those who had consumed alcohol within the last 6 hours, and the injury sample overall, highlights the need for further research to explore the relationship between the occurrence of injury and the drinking patterns and environments associated with injury. Further research is also required to assess the efficacy of early and brief interventions for alcohol and drug use within the emergency ward setting. This information would enable appropriate public health interventions to be initiated.
Establishment of a consistent L929 bioassay system for TNF‐α quantitation to evaluate the effect of lipopolysaccharide, phytomitogens and cytodifferentiation agents on cytotoxicity of TNF‐α secreted by adherent human mononuclear cells
Authors: Shiau Ming-Yuh , Chiou Hui-Ling , Lee Yao-Ling , Kuo Tzer-Min , Chang Yih-Hsin
Published: November 2003

Tumor necrosis factor‐α (TNF‐α ) plays an important role in the pathogenesis of rheumatoid arthritis. The present study was to evaluate the effects of lipopolysaccharide (LPS), phytomitogens and cytodifferentiation agents on cytotoxicity of TNF‐α secreted by adherent human mononuclear cells (AMC). TNF‐α cytotoxicity in LPS‐treated, phytomitogen‐treated, and cytodifferentiation agent‐treated AMC supernatants were analyzed by the L929 bioassay system. Our results showed that LPS could induce homogeneous TNF‐α production by AMC whereas, in addition to TNF‐α, phytomitogens could also induce other TNF‐like factors. Neither methotrexate, retinoic acid nor sodium butyrate can inhibit TNF‐α cytotoxicity, while hexamethylene bisacetamide could not only inhibit TNF‐α cytotoxicity but also TNF‐α inducing ability of LPS to AMC.