bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrolyte-gated charge accumulation in organic single crystals
Authors: Shimotani Hidekazu , Asanuma Haruhiko , Takeya Jun , Iwasa Yoshihiro
Published: November 2006

Comparative studies of electrolyte-gated and SiO2-gated field-effect transistors have been carried out on rubrene single crystals by experimentally estimating their accumulated charges. The capacitance of the electrolyte gate at 1mHz was 15μF∕cm2, which is more than two orders of magnitude larger than that of the 100-nm-thick SiO2 gate dielectric. The maximum carrier density in the electrolyte gate was 0.33hole∕molecule, which is considerably larger than that in the SiO2 gate. Furthermore, the transfer characteristics of the electrolyte-gate field-effect transistor showed reversible-peak behavior at an accumulated carrier density of 0.23hole∕molecule.
Improvement of near-ultraviolet nitride-based light emitting diodes with mesh indium tin oxide contact layers
Authors: Kuo C. H. , Chen C. M. , Kuo C. W. , Tun C. J. , Pan C. J. , Pong B. J. , Chi G. C.
Published: November 2006

The authors have demonstrated nitride-based near-ultraviolet (NUV) light emitting diodes (LEDs) with mesh indium tin oxide (ITO) contact layer. With 20mA injection current, it was found that forward voltages were 3.94 and 4.05V while the output powers were 7.54 and 9.02mW for the planar ITO LED and mesh ITO LED, respectively. The larger LED output power should be attributed partially to the reduced absorption of ITO in the NUV region and partially to the better current spreading.
Long-range excitations in time-dependent density functional theory
Authors: Maitra Neepa T. , Tempel David G.
Published: November 2006

Adiabatic time-dependent density functional theory fails for excitations of a heteroatomic molecule composed of two open-shell fragments at large separation. Strong frequency dependence of the exchange-correlation kernel is necessary for both local and charge-transfer excitations. The root of this is the static correlation created by the step in the exact Kohn-Sham ground-state potential between the two fragments. An approximate nonempirical kernel is derived for excited molecular dissociation curves at large separation. Our result is also relevant when the usual local and semilocal approximations are used for the ground-state potential, as static correlation there arises from the coalescence of the highest occupied and lowest unoccupied orbital energies as the molecule dissociates.
Temperature dependence of the GaAsN conduction band structure
Authors: Grau A. , Passow T. , Hetterich M.
Published: November 2006

In this contribution the authors investigate the temperature-dependent conduction band structure of GaAs1−xNx for different nitrogen contents. An analysis of their experimental photoreflectance data based on the two-band version of the band anticrossing model shows that with decreasing temperature the energy of the effective nitrogen level EN in GaAsN epilayers shifts significantly to higher energies. Simultaneously, the coupling parameter CNM between the nitrogen states and the host conduction band also rises to higher values.
Structural and electrical properties of low pressure metalorganic chemical vapor deposition grown Eu2O3 films on Si(100)
Authors: Singh M. P. , Shalini K. , Shivashankar S. A. , Deepak G. C. , Bhat N.
Published: November 2006

Structural and electrical properties of Eu2O3 films grown on Si(100) in 500–600°C temperature range by low pressure metalorganic chemical vapor deposition are reported. As-grown films also possess the impurity Eu1−xO phase, which has been removed upon annealing in O2 ambient. Film’s morphology comprises uniform spherical mounds (40–60nm). Electrical properties of the films, as examined by capacitance-voltage measurements, exhibit fixed oxide charges in the range of −1.5×1011to−6.0×1010cm−2 and dielectric constant in the range of 8–23. Annealing has resulted in drastic improvement of their electrical properties. Effect of oxygen nonstoichiometry on the film’s property is briefly discussed.
Fluorescence in nanostructured fulleride films
Authors: Lobo R. F. M. , Costa M. S. , Ribeiro J. H. F. , Sequeira C. A. C. , Pereira P.
Published: November 2006

Nanostructuring of fullerene C60 beam deposited films is achieved by electrochemical reduction in a potassium hydroxide aqueous solution. Alkali fulleride clusters are formed at the electrode, as it is illustrated by cyclic voltammetry, x-ray diffraction, and scanning tunneling microscopy. Fluorescence emission from fluorophore doped fullerene reduced films was investigated by fluorescence spectroscopy and scanning near-field optical microscopy. These techniques lead to results which also fit such nanometer-sized fulleride cluster interpretation. In particular, the fluorophore fluorescence lifetime decreases as long as aggregation in the film is more effective, which occurs with the increase of film thickness.
Aluminum oxynitride interfacial passivation layer for high-permittivity gate dielectric stack on gallium arsenide
Authors: Zhu Ming , Tung Chih-Hang , Yeo Yee-Chia
Published: November 2006

The authors demonstrate a passivation technique for GaAs substrate by employing an aluminum oxynitride (AlON) interfacial passivation layer. X-ray photoelectron spectroscopy and transmission electron microscopy results show that the AlON interfacial passivation layer effectively suppresses the formation of Ga or As oxide during the gate dielectric deposition process. This enabled the fabrication of high quality GaAs n-channel metal-oxide-semiconductor capacitors with HfO2 gate dielectric and TaN metal gate electrode. The metal gate/high-k gate dielectric stack on GaAs demonstrated an equivalent SiO2 thickness of 2.2nm and low leakage current density of 4.27×10−4A∕cm2 at a gate bias equal to Vfb−1V. Excellent capacitance-voltage characteristics with low frequency dispersion (∼4%) were also obtained.
Secondary structure provides a template for the folding of nearby polypeptides
Authors: Kameda Tomoshi , Takada Shoji
Published: November 2006

Although protein structures are primarily encoded by their sequences, they are also critically dependent on environmental factors such as solvents and interactions with other molecules. Here we investigate how the folding-energy landscape of a short peptide is altered by interactions with another peptide, by performing atomistic replica-exchange molecular dynamics simulations of polyalanines in various environments. We analyzed the free-energy landscapes of Ala
7
and Ala
8
in isolation, near an α-helix template, and near a β-strand template. The isolated Ala
7
and Ala
8
at 270 K were mainly in polyproline II helix conformations and in equilibrium between the α-helix and polyproline II helix, respectively, in harmony with the experiment. Interestingly, we found remarkably strong secondary-structure “templating”; namely, the α-helix template enhanced α-helix conformation and the β-strand template induced β-strand conformation in the simulated Ala
8
. The α-helix template lowered the nearby dielectric constant, which strengthened hydrogen bonds in the simulated Ala
8
, leading to α-helix stabilization. The β-strand template provided hydrogen bond positions to the simulated Ala
8
, sharply inducing β-strand structure. With or without templates, the energy landscape of Ala
8
is always funnel-like and centered at the α-helix conformation, whereas entropic contribution disfavors the α-helix, leading to subtle competition. Secondary-structure templating may play a critical role in protein conformation dynamics in the cellular environment.
Adrenergic modulation of NMDA receptors in prefrontal cortex is differentially regulated by RGS proteins and spinophilin
Authors: Liu Wenhua , Yuen Eunice Y. , Allen Patrick B. , Feng Jian , Greengard Paul , Yan Zhen
Published: November 2006

The noradrenergic system in the prefrontal cortex (PFC) is involved in many physiological and psychological processes, including working memory and mood control. To understand the functions of the noradrenergic system, we examined the regulation of NMDA receptors (NMDARs), key players in cognition and emotion, by α1- and α2-adrenergic receptors (α1-ARs, α2-ARs) in PFC pyramidal neurons. Applying norepinephrine or a norepinephrine transporter inhibitor reduced the amplitude but not paired-pulse ratio of NMDAR-mediated excitatory postsynaptic currents (EPSC) in PFC slices. Specific α1-AR or α2-AR agonists also decreased NMDAR-EPSC amplitude and whole-cell NMDAR current amplitude in dissociated PFC neurons. The α1-AR effect depended on the phospholipase C–inositol 1,4,5-trisphosphate–Ca2+pathway, whereas the α2-AR effect depended on protein kinase A and the microtubule-based transport of NMDARs that is regulated by ERK signaling. Furthermore, two members of the RGS family, RGS2 and RGS4, were found to down-regulate the effect of α1-AR on NMDAR currents, whereas only RGS4 was involved in inhibiting α2-AR regulation of NMDAR currents. The regulating effects of RGS2/4 on α1-AR signaling were lost in mutant mice lacking spinophilin, which binds several RGS members and G protein-coupled receptors, whereas the effect of RGS4 on α2-AR signaling was not altered in spinophilin-knockout mice. Our work suggests that activation of α1-ARs or α2-ARs suppresses NMDAR currents in PFC neurons by distinct mechanisms. The effect of α1-ARs is modified by RGS2/4 that are recruited to the receptor complex by spinophilin, whereas the effect of α2-ARs is modified by RGS4 independent of spinophilin.
Positive selection of yeast nonhomologous end-joining genes and a retrotransposon conflict hypothesis
Authors: Sawyer Sara L. , Malik Harmit S.
Published: November 2006

Transposable elements have clearly played a major role in shaping both the size and organization of eukaryotic genomes. However, the evolution of essential genes in core biological processes may also have been shaped by coevolution with these elements. This would be predicted to occur in instances where host proteins are either hijacked for use by mobile elements or recruited to defend against them. To detect such cases, we have used the
Saccharomyces cerevisiae
–
Saccharomyces paradoxus
sibling species pair to identify genes that have evolved under positive selection. We identify 72 such genes, which participate in a variety of biological processes but are enriched for genes involved in meiosis and DNA repair by nonhomologous end-joining (NHEJ). We confirm the signature of positive selection acting on NHEJ genes using orthologous sequences from all seven
Saccharomyces sensu stricto
species. Previous studies have found altered rates of Ty retrotransposition when these NHEJ genes are disrupted. We propose that the evolution of these repair proteins is likely to have been shaped by their interactions with Ty elements. Antagonistic pleiotropy, where critical genes like those involved in DNA repair are also subject to selective pressures imposed by mobile elements, could favor alleles that might be otherwise deleterious for their normal roles related to genome stability.
Conservation and evolution of gene coexpression networks in human and chimpanzee brains
Authors: Oldham Michael C. , Horvath Steve , Geschwind Daniel H.
Published: November 2006

Comparisons of gene expression between human and non-human primate brains have identified hundreds of differentially expressed genes, yet translating these lists into key functional distinctions between species has proved difficult. Here we provide a more integrated view of human brain evolution by examining the large-scale organization of gene coexpression networks in human and chimpanzee brains. We identify modules of coexpressed genes that correspond to discrete brain regions and quantify their conservation between the species. Module conservation in cerebral cortex is significantly weaker than module conservation in subcortical brain regions, revealing a striking gradient that parallels known evolutionary hierarchies. We introduce a method for identifying species-specific network connections and demonstrate how differential network connectivity can be used to identify key drivers of evolutionary change. By integrating our results with comparative genomic sequence data and estimates of protein sequence divergence rates, we confirm a number of network predictions and validate these findings. Our results provide insights into the molecular bases of primate brain organization and demonstrate the general utility of weighted gene coexpression network analysis.
Mapping the
Sinorhizobium meliloti
1021 solute-binding protein-dependent transportome
Authors: Mauchline T. H. , Fowler J. E. , East A. K. , Sartor A. L. , Zaheer R. , Hosie A. H. F. , Poole P. S. , Finan T. M.
Published: November 2006

The number of solute-binding protein-dependent transporters in rhizobia is dramatically increased compared with the majority of other bacteria so far sequenced. This increase may be due to the high affinity of solute-binding proteins for solutes, permitting the acquisition of a broad range of growth-limiting nutrients from soil and the rhizosphere. The transcriptional induction of these transporters was studied by creating a suite of plasmid and integrated fusions to nearly all ATP-binding cassette (ABC) and tripartite ATP-independent periplasmic (TRAP) transporters of
Sinorhizobium meliloti
. In total, specific inducers were identified for 76 transport systems, amounting to ≈47% of the ABC uptake systems and 53% of the TRAP transporters in
S. meliloti
. Of these transport systems, 64 are previously uncharacterized in
Rhizobia
and 24 were induced by solutes not known to be transported by ABC- or TRAP-uptake systems in any organism. This study provides a global expression map of one of the largest transporter families (transportome) and an invaluable tool to both understand their solute specificity and the relationships between members of large paralogous families.
Revertant mutants G550E and 4RK rescue cystic fibrosis mutants in the first nucleotide-binding domain of CFTR by different mechanisms
Authors: Roxo-Rosa Mónica , Xu Zhe , Schmidt André , Neto Mário , Cai Zhiwei , Soares Cláudio M. , Sheppard David N. , Amaral Margarida D.
Published: November 2006

The revertant mutations G550E and 4RK [the simultaneous mutation of four arginine-framed tripeptides (AFTs): R29K, R516K, R555K, and R766K] rescue the cell surface expression and function of F508del-cystic fibrosis (CF) transmembrane conductance regulator (-CFTR), the most common CF mutation. Here, we investigate their mechanism of action by using biochemical and functional assays to examine their effects on F508del and three CF mutations (R560T, A561E, and V562I) located within a conserved region of the first nucleotide-binding domain (NBD1) of CFTR. Like F508del, R560T and A561E disrupt CFTR trafficking. G550E rescued the trafficking defect of A561E but not that of R560T. Of note, the processing and function of V562I were equivalent to that of wild-type (wt)-CFTR, suggesting that V562I is not a disease-causing mutation. Biochemical studies revealed that 4RK generates higher steady-state levels of mature CFTR (band C) for wt- and V562I-CFTR than does G550E. Moreover, functional studies showed that the revertants rescue the gating defect of F508del-CFTR with different efficacies. 4RK modestly increased F508del-CFTR activity by prolonging channel openings, whereas G550E restored F508del-CFTR activity to wt levels by altering the duration of channel openings and closings. Thus, our data suggest that the revertants G550E and 4RK might rescue F508del-CFTR by distinct mechanisms. G550E likely alters the conformation of NBD1, whereas 4RK allows F508del-CFTR to escape endoplasmic reticulum retention/retrieval mediated by AFTs. We propose that AFTs might constitute a checkpoint for endoplasmic reticulum quality control.
Evolution and expression of chimeric POTE–actin genes in the human genome
Authors: Lee Yoomi , Ise Tomoko , Ha Duc , Saint Fleur Ashley , Hahn Yoonsoo , Liu Xiu-Fen , Nagata Satoshi , Lee Byungkook , Bera Tapan K. , Pastan Ira
Published: November 2006

We previously described a primate-specific gene family, POTE, that is expressed in many cancers but in a limited number of normal organs. The 13 POTE genes are dispersed among eight different chromosomes and evolved by duplications and remodeling of the human genome from an ancestral gene, ANKRD26. Based on sequence similarity, the POTE gene family members can be divided into three groups. By genome database searches, we identified an actin retroposon insertion at the carboxyl terminus of one of the ancestral POTE paralogs. By Northern blot analysis, we identified the expected 7.5-kb POTE–actin chimeric transcript in a breast cancer cell line. The protein encoded by the POTE–actin transcript is predicted to be 120 kDa in size. Using anti-POTE mAbs that recognize the amino-terminal portion of the POTE protein, we detected the 120-kDa POTE–actin fusion protein in breast cancer cell lines known to express the fusion transcript. These data demonstrate that insertion of a retroposon produced an altered functional POTE gene. This example indicates that new functional human genes can evolve by insertion of retroposons.
Change in chronic disability from 1982 to 2004/2005 as measured by long-term changes in function and health in the U.S. elderly population
Authors: Manton Kenneth G. , Gu XiLiang , Lamb Vicki L.
Published: November 2006

Changes in the health and functioning of the Medicare-enrolled population aged 65+ are tracked by using the 1982–2004/2005 National Long-Term Care Surveys. We found a significant rate of decline in the prevalence of chronic disability that accelerated from 1982 to 2004. These declines are significant for both persons with less severe chronic disability, which might be compensated by modifying the built environment and providing assistive devices, and for persons with more serious disability, which may be affected by reductions in the incidence and severity of disease through biomedical interventions. Declines in chronic disability continued over the 22-year period at a rate fast enough (i.e., 1.52% per annum) to contribute significantly to the long-term fiscal stability of the Medicare (and Medicaid) programs. Changes in the rate and substance of disability declines seem consistent with the intentions of policy interventions in Medicare and Medicaid.
Oncogenic steroid receptor coactivator-3 is a key regulator of the white adipogenic program
Authors: Louet Jean-Francois , Coste Agnès , Amazit Larbi , Tannour-Louet Mounia , Wu Ray-Chang , Tsai Sophia Y. , Tsai Ming-Jer , Auwerx Johan , O'Malley Bert W.
Published: November 2006

The white adipocyte is at the center of dysfunctional regulatory pathways in various pathophysiological processes, including obesity, diabetes, inflammation, and cancer. Here, we show that the oncogenic steroid receptor coactivator-3 (SRC-3) is a critical regulator of white adipocyte development. Indeed, in
SRC-3
−/−
mouse embryonic fibroblasts, adipocyte differentiation was severely impaired, and reexpression of SRC-3 was able to restore it. The early stages of adipocyte differentiation are accompanied by an increase in nuclear levels of SRC-3, which accumulates to high levels specifically in the nucleus of differentiated fat cells. Moreover,
SRC-3
−/−
animals showed reduced body weight and adipose tissue mass with a significant decrease of the expression of peroxisome proliferator-activated receptor γ2 (PPARγ2), a master gene required for adipogenesis. At the molecular level, SRC-3 acts synergistically with the transcription factor CAAT/enhancer-binding protein to control the gene expression of PPARγ2. Collectively, these data suggest a crucial role for SRC-3 as an integrator of the complex transcriptional network controlling adipogenesis.
Molecular mechanism for analgesia involving specific antagonism of α9α10 nicotinic acetylcholine receptors
Authors: Vincler Michelle , Wittenauer Shannon , Parker Renee , Ellison Michael , Olivera Baldomero M. , McIntosh J. Michael
Published: November 2006

α9α10 nicotinic acetylcholine receptors (nAChRs) have been identified in a variety of tissues including lymphocytes and dorsal root ganglia; except in the case of the auditory system, the function of α9α10 nAChRs is not known. Here we show that selective block (rather than stimulation) of α9α10 nAChRs is analgesic in an animal model of nerve injury pain. In addition, blockade of this nAChR subtype reduces the number of choline acetyltransferase-positive cells, macrophages, and lymphocytes at the site of injury. Chronic neuropathic pain is estimated to affect up to 8% of the world's population; the numerous analgesic compounds currently available are largely ineffective and act through a small number of pharmacological mechanisms. Our findings not only suggest a molecular mechanism for the treatment of neuropathic pain but also demonstrate the involvement of α9α10 nAChRs in the pathophysiology of peripheral nerve injury.
An unconventional pathway for reduction of CO
2
to methane in CO-grown
Methanosarcina acetivorans
revealed by proteomics
Authors: Lessner Daniel J. , Li Lingyun , Li Qingbo , Rejtar Tomas , Andreev Victor P. , Reichlen Matthew , Hill Kevin , Moran James J. , Karger Barry L. , Ferry James G.
Published: November 2006

Methanosarcina acetivorans
produces acetate, formate, and methane when cultured with CO as the growth substrate [Rother M, Metcalf WW (2004)
Proc Natl Acad Sci USA
101:
16929–16934
], which suggests novel features of CO metabolism. Here we present a genome-wide proteomic approach to identify and quantify proteins differentially abundant in response to growth on CO versus methanol or acetate. The results indicate that oxidation of CO to CO
2
supplies electrons for reduction of CO
2
to a methyl group by steps and enzymes of the pathway for CO
2
reduction determined for other methane-producing species. However, proteomic and quantitative RT-PCR results suggest that reduction of the methyl group to methane involves novel methyltransferases and a coenzyme F
420
H
2
:heterodisulfide oxidoreductase system that generates a proton gradient for ATP synthesis not previously described for pathways reducing CO
2
to methane. Biochemical assays support a role for the oxidoreductase, and transcriptional mapping identified an unusual operon structure encoding the oxidoreductase. The proteomic results further indicate that acetate is synthesized from the methyl group and CO by a reversal of initial steps in the pathway for conversion of acetate to methane that yields ATP by substrate level phosphorylation. The results indicate that
M. acetivorans
utilizes a pathway distinct from all known CO
2
reduction pathways for methane formation that reflects an adaptation to the marine environment. Finally, the pathway supports the basis for a recently proposed primitive CO-dependent energy-conservation cycle that drove and directed the early evolution of life on Earth.
Constraints on Voltage Sensor Movement in the Shaker K+ Channel
Authors: Darman Rachel B. , Ivy Allison A. , Ketty Vina , Blaustein Robert O.
Published: November 2006

In nerve and muscle cells, the voltage-gated opening and closing of cation-selective ion channels is accompanied by the translocation of 12–14 elementary charges across the membrane's electric field. Although most of these charges are carried by residues in the S4 helix of the gating module of these channels, the precise nature of their physical movement is currently the topic of spirited debate. Broadly speaking, two classes of models have emerged: those that suggest that small-scale motions can account for the extensive charge displacement, and those that invoke a much larger physical movement. In the most recent incarnation of the latter type of model, which is based on structural and functional data from the archaebacterial K+ channel KvAP, a “voltage-sensor paddle” comprising a helix-turn-helix of S3–S4 translocates ∼20 Å through the bilayer during the gating cycle (Jiang, Y., A. Lee, J. Chen, V. Ruta, M. Cadene, B.T. Chait, and R. MacKinnon. 2003. Nature. 423:33–41; Jiang, Y., V. Ruta, J. Chen, A. Lee, and R. MacKinnon. 2003. Nature. 423:42–48.; Ruta, V., J. Chen, and R. MacKinnon. 2005. Cell. 123:463–475). We used two methods to test for analogous motions in the Shaker K+ channel, each examining the aqueous exposure of residues near S3. In the first, we employed a pore-blocking maleimide reagent (Blaustein, R.O., P.A. Cole, C. Williams, and C. Miller. 2000. Nat. Struct. Biol. 7:309–311) to probe for state-dependent changes in the chemical reactivity of substituted cysteines; in the second, we tested the state-dependent accessibility of a tethered biotin to external streptavidin (Qiu, X.Q., K.S. Jakes, A. Finkelstein, and S.L. Slatin. 1994. J. Biol. Chem. 269:7483–7488; Slatin, S.L., X.Q. Qiu, K.S. Jakes, and A. Finkelstein. 1994. Nature. 371:158–161). In both types of experiments, residues predicted to lie near the top of S3 did not exhibit any change in aqueous exposure during the gating cycle. This lack of state dependence argues against large-scale movements, either axially or radially, of Shaker's S3–S4 voltage-sensor paddle.
CGI: a new approach for prioritizing genes by combining gene expression and protein–protein interaction data
Authors: Ma Xiaotu , Lee Hyunju , Wang Li , Sun Fengzhu
Published: November 2006

Motivation: Identifying candidate genes associated with a given phenotype or trait is an important problem in biological and biomedical studies. Prioritizing genes based on the accumulated information from several data sources is of fundamental importance. Several integrative methods have been developed when a set of candidate genes for the phenotype is available. However, how to prioritize genes for phenotypes when no candidates are available is still a challenging problem.

Results: We develop a new method for prioritizing genes associated with a phenotype by Combining Gene expression and protein Interaction data (CGI). The method is applied to yeast gene expression data sets in combination with protein interaction data sets of varying reliability. We found that our method outperforms the intuitive prioritizing method of using either gene expression data or protein interaction data only and a recent gene ranking algorithm GeneRank. We then apply our method to prioritize genes for Alzheimer's disease.

Availability: The code in this paper is available upon request.

Contact:  fsun@usc.edu

Supplementary data: Supplementary data are available at Bioinformatics online.
Differential involvement of hippocampal calcineurin during learning and reversal learning in a Y-maze task
Authors: Havekes Robbert , Nijholt Ingrid M. , Luiten Paul G.M. , Van der Zee Eddy A.
Published: November 2006

The regulation and function of the calcium-dependent phosphatase calcineurin (CaN, protein phosphatase 2B) in learning and memory remain unclear, although recent work indicates that CaN may play a differential role in training and reversal training. To gain more insight into the involvement of CaN in these two types of learning, hippocampal CaN activity, protein levels, and expression patterns were studied in mice subjected to a reference memory version of the Y-maze task. We show that (1) training but not habituation induces a decrease in cytosolic CaN activity, (2) the recovery of cytosolic CaN activity is reversal training specific and does not reflect normal restoration of basal levels unrelated to subsequent learning, (3) cytosolic protein levels for the catalytic subunit of CaN (CaNA) are decreased at the early phase of training, but not at the early phase of reversal training, (4) CaNA immunoreactivity in the dorsal hippocampus is enhanced in the CA1 and CA3 area (but not in the dentate gyrus [DG] or subiculum [SUB]) only during reversal training. These findings indicate that memory formation is accompanied by reduced CaN activity, whereas adapting to changes in a familiar environment is accompanied by restored CaN activity. Moreover, reversal training selectively affects hippocampal CA3 and CA1 regions, suggesting a specific function of these hippocampal subregions in reversal learning.
Emotional memories are not all created equal: Evidence for selective memory enhancement
Authors: Anderson Adam K. , Yamaguchi Yuki , Grabski Wojtek , Lacka Dominika
Published: November 2006

Human brain imaging studies have shown that greater amygdala activation to emotional relative to neutral events leads to enhanced episodic memory. Other studies have shown that fearful faces also elicit greater amygdala activation relative to neutral faces. To the extent that amygdala recruitment is sufficient to enhance recollection, these separate lines of evidence predict that recognition memory should be greater for fearful relative to neutral faces. Experiment 1 demonstrated enhanced memory for emotionally negative relative to neutral scenes; however, fearful faces were not subject to enhanced recognition across a variety of delays (15 min to 2 wk). Experiment 2 demonstrated that enhanced delayed recognition for emotional scenes was associated with increased sympathetic autonomic arousal, indexed by the galvanic skin response, relative to fearful faces. These results suggest that while amygdala activation may be necessary, it alone is insufficient to enhance episodic memory formation. It is proposed that a sufficient level of systemic arousal is required to alter memory consolidation resulting in enhanced recollection of emotional events.
Association of Specific Expansins with Growth in Maize Leaves Is Maintained under Environmental, Genetic, and Developmental Sources of Variation
Authors: Muller Bertrand , Bourdais Gildas , Reidy Beat , Bencivenni Christelle , Massonneau Agnès , Condamine Pascal , Rolland Gaëlle , Conéjéro Geneviève , Rogowsky Peter , Tardieu François
Published: November 2006

We aimed to evaluate whether changes in maize (Zea mays) leaf expansion rate in response to environmental stimuli or developmental gradients are mediated by common or specific expansins, a class of proteins known to enhance cell wall extensibility. Among the 33 maize expansin or putative expansin genes analyzed, 19 were preferentially expressed at some point of the leaf elongation zone and these expansins could be organized into three clusters related to cell division, maximal leaf expansion, and cell wall differentiation. Further analysis of the spatial distribution of expression was carried out for three expansins in leaves displaying a large range of expansion rates due to water deficit, genotype, and leaf developmental stage. With most sources of variation, the three genes showed similar changes in expression and consistent association with changes in leaf expansion. Moreover, our analysis also suggested preferential association of each expansin with elongation, widening, or both of these processes. Finally, using in situ hybridization, expression of two of these genes was increased in load-bearing tissues such as the epidermis and differentiating xylem. Together, these results suggest that some expansins may be preferentially related to elongation and widening after integrating several spatial, environmental, genetic, and developmental cues.
A Novel Family of Lectins Evolutionarily Related to Class V Chitinases: An Example of Neofunctionalization in Legumes
Authors: Van Damme Els J.M. , Culerrier Raphaël , Barre Annick , Alvarez Richard , Rougé Pierre , Peumans Willy J.
Published: November 2006

A lectin has been identified in black locust (Robinia pseudoacacia) bark that shares approximately 50% sequence identity with plant class V chitinases but is essentially devoid of chitinase activity. Specificity studies indicated that the black locust chitinase-related agglutinin (RobpsCRA) preferentially binds to high-mannose N-glycans comprising the proximal pentasaccharide core structure. Closely related orthologs of RobpsCRA could be identified in the legumes Glycine max, Medicago truncatula, and Lotus japonicus but in no other plant species, suggesting that this novel lectin family most probably evolved in an ancient legume species or possibly an earlier ancestor. This identification of RobpsCRA not only illustrates neofunctionalization in plants, but also provides firm evidence that plants are capable of developing a sugar-binding domain from an existing structural scaffold with a different activity and accordingly sheds new light on the molecular evolution of plant lectins.
Functional Conservation of a Root Hair Cell-Specificcis-Element in Angiosperms with Different Root Hair Distribution Patterns
Authors: Kim Dong Wook , Lee Sang Ho , Choi Sang-Bong , Won Su-Kyung , Heo Yoon-Kyung , Cho Misuk , Park Youn-Il , Cho Hyung-Taeg
Published: November 2006

Vascular plants develop distinctive root hair distribution patterns in the root epidermis, depending on the taxon. The three patterns, random (Type 1), asymmetrical cell division (Type 2), and positionally cued (Type 3), are controlled by different upstream fate-determining factors that mediate expression of root hair cell-specific genes for hair morphogenesis. Here, we address whether these root hair genes possess a common transcriptional regulatory module (cis-element) determining cell-type specificity despite differences in the final root hair pattern. We identified Arabidopsis thaliana expansinA7 (At EXPA7) orthologous (and paralogous) genes from diverse angiosperm species with different hair distribution patterns. The promoters of these genes contain conserved root hair–specific cis-elements (RHEs) that were functionally verified in the Type-3 Arabidopsis root. The promoter of At EXPA7 (Type-3 pattern) also showed hair cell–specific expression in the Type 2 rice (Oryza sativa) root. Root hair–specific genes other than EXPAs also carry functionally homologous RHEs in their promoters. The RHE core consensus was established by a multiple alignment of functionally characterized RHEs from different species and by high-resolution analysis of At EXPA7 RHE1. Our results suggest that this regulatory module of root hair–specific genes has been conserved across angiosperms despite the divergence of upstream fate-determining machinery.
My Child Is Better Than Average: The Extension and Restriction of Unrealistic Optimism1
Authors: Lench Heather C. , Quas Jodi A. , Edelstein Robin S.
Published: November 2006

The purpose of the current study was to determine whether parents make unrealistic evaluations of children and what factors predict these evaluations. Parents of 5‐ and 6‐year‐olds rated their child's risk for various positive and negative outcomes, temperament, and health and behavior problems. Parents also completed an adult attachment measure. Parents appeared to give relatively little consideration to realistic constraints when predicting their child's future. Parents scoring higher on attachment avoidance were less optimistic that their child would attain positive outcomes and avoid negative outcomes, consistent with the view that optimism is a motivated phenomenon. Greater child internalizing behaviors also were associated with less parental optimism for positive outcomes. Findings have implications for the delivery of health messages to parents.
α‐Defensin increase in peripheral blood mononuclear cells from patients with hepatitis C virus chronic infection
Authors: Aceti A. , Mangoni M. L. , Pasquazzi C. , Fiocco D. , Marangi M. , Miele R. , Zechini B. , Borro M. , Versace I. , Simmaco M.
Published: November 2006

Summary.  The α‐defensin genes promoter regions contain a putative nuclear factors of activated T cells (NFAT)‐binding site and it is known that hepatitis C virus (HCV) core protein activates the interleukin (IL)‐2 gene transcription through the NFAT pathway. The aims of this study were to investigate if HCV affects the α‐defensin expression in peripheral human mononuclear cells (PBMCs) and to evaluate the existence of a correlation between α‐defensins and liver damage in patients with chronic hepatitis C. Ninety patients with chronic hepatitis C, 30 with chronic hepatitis B and 25 healthy controls were enrolled. α‐Defensins were identified and quantified in PBMCs by mass spectrometry, enzyme‐linked immunosorbent assay, antibacterial activity and mRNA levels. PBMCs from three patients and controls were stimulated with HCV core protein, hepatitis B virus core antigen and the α‐defensin mRNAs level was quantified. We found that HCV core protein activates in vitro the α‐defensin transcription. α‐Defensin levels in patients with chronic hepatitis C (mean ± SD = 1.103 ± 0.765 ng/106 cells), chronic hepatitis B (0.53 ± 0.15) and healthy controls (0.217 ± 0.09) resulted significantly different (P < 0.001). In patients with chronic hepatitis C, the α‐defensin levels and antibacterial activity correlate with the liver fibrosis. Our data suggest that HCV induces α‐defensin expression. The high linear correlation of α‐defensin levels with advancing fibrosis makes the measure of these peptides a reliable marker to evaluate fibrosis stage.
Founder effects, inbreeding and effective sizes in the Southern cattle tick: the effect of transmission dynamics and implications for pest management
Authors: KOFFI BROU BASILE , DE MEEÛS THIERRY , BARRÉ NICOLAS , DURAND PATRICK , ARNATHAU CÉLINE , CHEVILLON CHRISTINE
Published: November 2006

Since its immigration in the Pacific island of New Caledonia in 1942 (i.e. about 240 tick‐generations ago), the cattle tick Boophilus microplus has experienced a remarkable adaptive diversification there. In order to better understand the population factors involved, we have investigated the B. microplus population structure on that main host‐species, Bos taurus. This study was based microsatellite loci and confirmed that the island colonization came along with a significant bottleneck. Knowledge on B. microplus biology led us to expect B. microplus populations to be composed of highly inbred lineages irregularly dispatched among the individual hosts belonging to the same herds. Instead, this study evidenced a weak inbreeding level and an absence of genetic differentiation within herds. Complementarily, a significant signal of isolation by distance exhibited that human‐traffic of cattle does not promote high tick dispersal within the island. Finally, the tick density was found to be about a few hundreds of reproducing adults per squared kilometre, for a gene dispersal range of about a few hundred metres per tick generation. Results are discussed with regard to the evolution of new adaptive changes.
A membrane‐bound FtsH protease is involved in osmoregulation in Synechocystis sp. PCC 6803: the compatible solute synthesizing enzyme GgpS is one of the targets for proteolysis
Authors: Stirnberg Marit , Fulda Sabine , Huckauf Jana , Hagemann Martin , Krämer Reinhard , Marin Kay
Published: November 2006

Protein quality control and proteolysis are involved in cell maintenance and environmental acclimatization in bacteria and eukaryotes. The AAA protease FtsH2 of the cyanobacterium Synechocystis sp. PCC 6803 was identified during a screening for mutants impaired in osmoregulation. The ftsH2– mutant was salt sensitive because of a decreased level of the osmoprotectant glucosylglycerol (GG). In spite of wild type‐like transcription of the ggpS gene in ftsH2– cells the GgpS protein content increased but only low levels of GgpS activity were observed. Consequently, salt tolerance of the ftsH2– mutant decreased while addition of external osmolyte complemented the salt sensitivity. The proteolytic degradation of the GgpS protein by FtsH2 was demonstrated by an in vitro assay using inverted membrane vesicles. The GgpS is part of a GG synthesizing complex, because yeast two‐hybrid screens identified a close interaction with the GG‐phosphate phosphatase. Besides GgpS as the first soluble substrate of a cyanobacterial FtsH protease, several other putative targets were identified by a proteomic approach. We present a novel molecular explanation for the salt‐sensitive phenotype of bacterial ftsH– mutants as the result of accumulation of inactive enzymes for compatible solute synthesis, in this case GgpS the key enzyme of GG synthesis.
The novel Hha/YmoA family of nucleoid‐associated proteins: use of structural mimicry to modulate the activity of the H‐NS family of proteins
Authors: Madrid Cristina , Balsalobre Carlos , García Jesús , Juárez Antonio
Published: November 2006

The Hha/YmoA family of proteins is a group of conserved, low‐molecular‐weight proteins involved in the regulation of gene expression. Studies performed in Escherichia coli, Salmonella sp. and Yersinia sp. highlight the contribution of these proteins in regulating bacterial virulence, horizontal gene transfer and cell physiology. Genes encoding such proteins are located on chromosomes and plasmids in different genera of Gram‐negative bacteria. Their mode of action is currently being analysed by studying direct binding of Hha to DNA and as a component of protein complexes with regulatory functions. Recent data on the interaction of Hha with the H‐NS family of proteins and structural information suggest a physiological role for such protein complexes in many aspects of gene regulation.
Endometrial thickness screening in premenopausal women with abnormal uterine bleeding
Authors: Getpook Chatpavit , Wattanakumtornkul Saranya
Published: November 2006

Aim:  To assess the role of measuring endometrial thickness by transvaginal ultrasonography (TVS) as a screening tool for abnormal uterine bleeding triage in premenopausal women.

Methods:  Between November 2002 and October 2004, endometrial thickness was measured by TVS in 111 premenopausal women with non‐cyclic abnormal uterine bleeding before dilatation and curettage.

Results:  Of the 111 women, 31 (27.9%) had an abnormal endometrium (hyperplasia 13.5%, polyps 5.4%, submucous myoma 5.4%, and adenocarcinoma 3.6%). An endometrial thickness of 8 mm showed optimal sensitivity and specificity (83.9% and 58.8%, respectively) and 90.4% negative predictive value (NPV) for an abnormal endometrium. When submucous myoma was excluded, the sensitivity, specificity, and NPV were 80%, 53.8%, and 89.6%, respectively.

Conclusion:  Endometrial thickness of 8 mm or less is less likely to be associated with malignant pathologies in premenopausal uterine bleeding.
Severe leg compartment syndrome associated with dorsal lithotomy position during radical hysterectomy
Authors: Yanazume Shintaro , Yanazume Yumi , Iwamoto Ichiro , Tsuji Takahiro , Yoshinaga Mitsuhiro , Douchi Tsutomu
Published: November 2006

We encountered a female patient with left‐leg compartment syndrome; a devastating complication, probably associated with prolonged dorsal lithotomy position during radical hysterectomy using intermittent pneumatic compression. This patient was intensively treated and fortunately recovered. However, leg compartment syndrome is poorly understood by gynecologists. We must always consider the potential risk of this life‐threatening complication when patients are placed in the dorsal lithotomy position for a prolonged period during extended surgery using intermittent external compression.
Analysis of uterine rupture in a tertiary center in Eastern Nepal: Lessons for obstetric care
Authors: Chuni Neena
Published: November 2006

Aim:  To determine the etiologic factors, clinical presentation, management and fetomaternal outcome in cases of rupture of the gravid uterus and propose preventive measures.

Methods:  A retrospective analysis of cases of uterine rupture was carried out at B.P. Koirala Institute of Health Sciences, Nepal, between February 1999 and January 2004.

Results:  There were 126 cases of uterine rupture with incidence of one in 112 deliveries. Twenty‐five patients (19.8%) had a cesarean scar. Obstructed labor was the common antecedent factor in the unscarred group (46.5%) and use of oxytocics accounted for maximum ruptures (44%) in the scarred category. Patients with an unscarred uterus presented with hypotension and intrauterine death (89.1%), while abdominal tenderness (76%) and fetal distress (64%) were common modes of presentation in the scarred category. Complete rupture was seen in 84.9% of patients. Lateral wall ruptures (71.3%) necessitating hysterectomy (75.2%) were seen in the unscarred group. Anterior ruptures (92%) and repair (84%) were common in the scarred category. Maternal mortality was 13.5% and perinatal mortality 83.3%; these were both higher in the unscarred uterus.

Conclusion:  The incidence of uterine rupture is high in Eastern Nepal and rupture of the unscarred uterus carries graver risks. Regular antenatal care, hospital deliveries and vigilance during labor with quick referral to a well‐equipped center will reduce the incidence of this condition.
Supernumerary ovary on sigmoid colon resembling an endometriotic lesion
Authors: Imir Gonca , Arici Sema , Cetin Meral , Kivanc Figen
Published: November 2006

A 30‐year‐old woman with a history of endometriosis and chronic pelvic pain had right‐sided pain and sonographic evaluation demonstrated a right ovarian cyst 5 cm in diameter. Laparotomy revealed a right ovarian cystic mass and the cystic mass was found on the sigmoid colon. After excision, histopathologic study revealed endometrioma for the ovarian cyst and a supernumerary ovary for the cystic mass on the sigmoid colon.
Denaturalizing Dispossession: Critical Ethnography in the Age of Resurgent Imperialism
Authors: Hart Gillian
Published: November 2006

Critical ethnographies and methods of relational comparison provide tools for reconfiguring area studies to challenge imperial visions of the world; for illuminating power‐laden processes of constitution, connection, and disconnection; and for identifying slippages, openings, contradictions, and possibilities for alliances. Crucial to this project are Lefebvrian conceptions of the production of space. In developing these arguments, this essay also intervenes in recent discussions of so‐called “primitive accumulation” as an ongoing process. It does so by drawing on research into connections between South Africa and East Asia, and using these relational comparisons to highlight the significance of specifically racialized forms of dispossession and their salience to struggles currently underway in South Africa. These examples underscore how critical ethnography and relational comparison provide a crucial means for “advancing to the concrete”—in the sense of concrete concepts that are adequate to the complexity with which they are seeking to grapple.
Elaborating on Elaborations: Role of Maternal Reminiscing Style in Cognitive and Socioemotional Development
Authors: Fivush Robyn , Haden Catherine A. , Reese Elaine
Published: November 2006

Initial research on maternal reminiscing style established clear and consistent individual differences that vary along a dimension of maternal elaboration and that are related to children's developing autobiographical skills. More recent research has linked maternal elaborative reminiscing to strategic memory development, language and literacy skills, developing attachment relationships, and understanding of self, other, and mind. In this review, this research is placed in theoretical context by arguing for the critical role of reminiscing in developmental process and outcome.
Children's Sensitivity to Their Own Relative Ignorance: Handling of Possibilities Under Epistemic and Physical Uncertainty
Authors: Robinson Elizabeth J. , Rowley Martin G. , Beck Sarah R. , Carroll Dan J. , Apperly Ian A.
Published: November 2006

Children more frequently specified possibilities correctly when uncertainty resided in the physical world (physical uncertainty) than in their own perspective of ignorance (epistemic uncertainty). In Experiment 1 (N=61), 4‐ to 6‐year‐olds marked both doors from which a block might emerge when the outcome was undetermined, but a single door when they knew the block was hidden behind one door. In Experiments 2 (N=30; 5‐ to 6‐year‐olds) and 3 (N=80; 5‐ to 8‐year‐olds), children placed food in both possible locations when an imaginary pet was yet to occupy one, but in a single location when the pet was already hidden in one. The results have implications for interpretive theory of mind and “curse of knowledge.”