bluuebunny/crossref_metadata_2025 huggingface dataset:
Rationally designed small compounds inhibit pilus biogenesis in uropathogenic bacteria
Authors: Pinkner Jerome S. , Remaut Han , Buelens Floris , Miller Eric , Åberg Veronica , Pemberton Nils , Hedenström Mattias , Larsson Andreas , Seed Patrick , Waksman Gabriel , Hultgren Scott J. , Almqvist Fredrik
Published: November 2006

A chemical synthesis platform with broad applications and flexibility was rationally designed to inhibit biogenesis of adhesive pili assembled by the chaperone–usher pathway in Gram-negative pathogens. The activity of a family of bicyclic 2-pyridones, termed pilicides, was evaluated in two different pilus biogenesis systems in uropathogenic
Escherichia coli
. Hemagglutination mediated by either type 1 or P pili, adherence to bladder cells, and biofilm formation mediated by type 1 pili were all reduced by ≈90% in laboratory and clinical
E. coli
strains. The structure of the pilicide bound to the P pilus chaperone PapD revealed that the pilicide bound to the surface of the chaperone known to interact with the usher, the outer-membrane assembly platform where pili are assembled. Point mutations in the pilicide-binding site dramatically reduced pilus formation but did not block the ability of PapD to bind subunits and mediate their folding. Surface plasmon resonance experiments confirmed that the pilicide interfered with the binding of chaperone–subunit complexes to the usher. These pilicides thus target key virulence factors in pathogenic bacteria and represent a promising proof of concept for developing drugs that function by targeting virulence factors.
Neuroglobin-overexpressing transgenic mice are resistant to cerebral and myocardial ischemia
Authors: Khan Adil A. , Wang Yaoming , Sun Yunjuan , Mao Xiao Ou , Xie Lin , Miles Erin , Graboski Justin , Chen Sylvia , Ellerby Lisa M. , Jin Kunlin , Greenberg David A.
Published: November 2006

Neuroglobin (Ngb), a protein related to myoglobin and hemoglobin but expressed predominantly in the brain, is induced by neuronal hypoxia and cerebral ischemia and protects against hypoxic or ischemic neuronal injury. We engineered transgenic mice that overexpress murine Ngb under the control of a chicken β-actin promoter, resulting in enhanced Ngb expression in multiple cell types and multiple tissues, including brain and heart. In Ngb-overexpressing transgenic mice compared with wild-type littermates, the volume of cerebral infarcts after occlusion of the middle cerebral artery was reduced by ≈30%, and the volume of myocardial infarcts produced by occlusion of the left anterior descending coronary artery was reduced by ≈25%. Ngb overexpression was associated with enhanced expression of endothelial nitric oxide synthase in vascular endothelial cells. These findings extend prior evidence for cytoprotection by Ngb and suggest both direct (parenchymatous) and indirect (vasomotor) protective mechanisms.
Na channel inactivation from open and closed states
Authors: Armstrong Clay M.
Published: November 2006

A sodium channel is composed of four similar domains, each containing a highly charged S4 helix that is driven outward (activates) in response to a depolarization. Functionally, the channel has two gates, called activation gate (
a
gate) and inactivation gate (I gate), both of which must be open for conduction to occur. The cytoplasmically located
a
gate opens after a depolarization has activated the S4s of (probably) all four domains. The I gate consists of a cytoplasmically located inactivation “particle” and a receptor for it in the channel. The receptor becomes available after some degree of S4 activation, and the particle diffuses in to inactivate the channel. The I gate usually closes when the
a
gate is open [open-state inactivation (Osi)] but also can close before the channel reaches the conducting state. This “closed-state inactivation” (Csi) is studied quantitatively in this paper to determine the degree of S4 activation required for (
i
) opening the
a
gate, and (
ii
) permitting the I gate to close. Csi is most prominent for small depolarizations, during which occupancy of the partially activated closed states is prolonged. Large depolarizations drive the S4s outward quickly, minimizing the duration of closed-state occupancy and making Csi small and Osi large. Based on these data and evidence in the literature, it is concluded that opening the
a
gate requires S4 activation in domains 1–3, with partial activation of the S4 of domain 4. Csi requires only S4 activation of domains 3 and 4, which does not open the
a
gate.
Synthetic selectivity through avoidance of valence frustration
Authors: Hutin Marie , Bernardinelli Gérald , Nitschke Jonathan R.
Published: November 2006

A series of di-copper(I) complexes has been prepared via the reaction of copper(I) tetrafluoroborate, 2,6-diformylpyridine, 8-aminoquinoline, and a series of aliphatic diamines and 4-substituted anilines. To avoid a “valence-frustrated” state, involving a mismatch between the number of ligand donor atoms and the number of metal acceptor sites, the product structures formed selectively: One of the formyl groups of the diformylpyridine reacted specifically with the aminoquinoline, whereas the other formyl group reacted with the diamine or aniline. The observed selectivity was demonstrated to be thermodynamic in nature: When two dicopper complexes that were stable yet “valence-frustrated” were mixed, an imine metathesis reaction was observed to occur spontaneously to generate a “valence-satisfied” structure. In addition to control over the constitution of the ligands, we were able to exercise control over their relative orientations within the complex. Diamines exclusively gave structures in which the ligand exhibited a head-to-head orientation along the copper–copper axis to avoid stretching. Anilines gave predominantly head-to-tail structures, with the proportion of head-to-head isomer decreasing in complexes that incorporate more electron-deficient anilines and disappearing in less polar solvents. We also demonstrated the removal of the metals and the hydrogenation of the imine bonds to generate a molecule containing nonexchanging secondary amines, suggesting potential uses of this technique in the domain of organic synthesis.
Returning forests analyzed with the forest identity
Authors: Kauppi Pekka E. , Ausubel Jesse H. , Fang Jingyun , Mather Alexander S. , Sedjo Roger A. , Waggoner Paul E.
Published: November 2006

Amid widespread reports of deforestation, some nations have nevertheless experienced transitions from deforestation to reforestation. In a causal relationship, the Forest Identity relates the carbon sequestered in forests to the changing variables of national or regional forest area, growing stock density per area, biomass per growing stock volume, and carbon concentration in the biomass. It quantifies the sources of change of a nation's forests. The Identity also logically relates the quantitative impact on forest expanse of shifting timber harvest to regions and plantations where density grows faster. Among 50 nations with extensive forests reported in the Food and Agriculture Organization's comprehensive Global Forest Resources Assessment 2005, no nation where annual per capita gross domestic product exceeded $4,600 had a negative rate of growing stock change. Using the Forest Identity and national data from the Assessment report, a single synoptic chart arrays the 50 nations with coordinates of the rates of change of basic variables, reveals both clusters of nations and outliers, and suggests trends in returning forests and their attributes. The Forest Identity also could serve as a tool for setting forest goals and illuminating how national policies accelerate or retard the forest transitions that are diffusing among nations.
ELYS is a dual nucleoporin/kinetochore protein required for nuclear pore assembly and proper cell division
Authors: Rasala Beth A. , Orjalo Arturo V. , Shen Zhouxin , Briggs Steven , Forbes Douglass J.
Published: November 2006

Nuclear pores span the nuclear envelope and act as gated aqueous channels to regulate the transport of macromolecules between the nucleus and cytoplasm, from individual proteins and RNAs to entire viral genomes. By far the largest subunit of the nuclear pore is the Nup107–160 complex, which consists of nine proteins and is critical for nuclear pore assembly. At mitosis, the Nup107–160 complex localizes to kinetochores, suggesting that it may also function in chromosome segregation. To investigate the dual roles of the Nup107–160 complex at the pore and during mitosis, we set out to identify binding partners by immunoprecipitation from both interphase and mitotic
Xenopus
egg extracts and mass spectrometry. ELYS, a putative transcription factor, was discovered to copurify with the Nup107–160 complex in
Xenopus
interphase extracts,
Xenopus
mitotic extracts, and human cell extracts. Indeed, a large fraction of ELYS localizes to the nuclear pore complexes of HeLa cells. Importantly, depletion of ELYS by RNAi leads to severe disruption of nuclear pores in the nuclear envelope, whereas lamin, Ran, and tubulin staining appear normal. At mitosis, ELYS targets to kinetochores, and RNAi depletion from HeLa cells leads to an increase in cytokinesis defects. Thus, we have identified an unexpected member of the nuclear pore and kinetochore that functions in both pore assembly at the nucleus and faithful cell division.
Organic haze on Titan and the early Earth
Authors: Trainer Melissa G. , Pavlov Alexander A. , DeWitt H. Langley , Jimenez Jose L. , McKay Christopher P. , Toon Owen B. , Tolbert Margaret A.
Published: November 2006

Recent exploration by the Cassini/Huygens mission has stimulated a great deal of interest in Saturn's moon, Titan. One of Titan's most captivating features is the thick organic haze layer surrounding the moon, believed to be formed from photochemistry high in the CH
4
/N
2
atmosphere. It has been suggested that a similar haze layer may have formed on the early Earth. Here we report laboratory experiments that demonstrate the properties of haze likely to form through photochemistry on Titan and early Earth. We have used a deuterium lamp to initiate particle production in these simulated atmospheres from UV photolysis. Using a unique analysis technique, the aerosol mass spectrometer, we have studied the chemical composition, size, and shape of the particles produced as a function of initial trace gas composition. Our results show that the aerosols produced in the laboratory can serve as analogs for the observed haze in Titan's atmosphere. Experiments performed under possible conditions for early Earth suggest a significant optical depth of haze may have dominated the early Earth's atmosphere. Aerosol size measurements are presented, and implications for the haze layer properties are discussed. We estimate that aerosol production on the early Earth may have been on the order of 10
14
g·year
−1
and thus could have served as a primary source of organic material to the surface.
Bayesian estimation of the shape skeleton
Authors: Feldman Jacob , Singh Manish
Published: November 2006

Skeletal representations of shape have attracted enormous interest ever since their introduction by Blum [Blum H (1973)J Theor Biol38:205–287], because of their potential to provide a compact, but meaningful, shape representation, suitable for both neural modeling and computational applications. But effective computation of the shape skeleton remains a notorious unsolved problem; existing approaches are extremely sensitive to noise and give counterintuitive results with simple shapes. In conventional approaches, the skeleton is defined by a geometric construction and computed by a deterministic procedure. We introduce a Bayesian probabilistic approach, in which a shape is assumed to have “grown” from a skeleton by a stochastic generative process. Bayesian estimation is used to identify the skeleton most likely to have produced the shape, i.e., that best “explains” it, called the maximuma posterioriskeleton. Even with natural shapes with substantial contour noise, this approach provides a robust skeletal representation whose branches correspond to the natural parts of the shape.
The von Hippel-Lindau tumor suppressor protein controls ciliogenesis by orienting microtubule growth
Authors: Schermer Bernhard , Ghenoiu Cristina , Bartram Malte , Müller Roman Ulrich , Kotsis Fruzsina , Höhne Martin , Kühn Wolfgang , Rapka Manuela , Nitschke Roland , Zentgraf Hanswalter , Fliegauf Manfred , Omran Heymut , Walz Gerd , Benzing Thomas
Published: November 2006

Cilia are specialized organelles that play an important role in several biological processes, including mechanosensation, photoperception, and osmosignaling. Mutations in proteins localized to cilia have been implicated in a growing number of human diseases. In this study, we demonstrate that the von Hippel-Lindau (VHL) protein (pVHL) is a ciliary protein that controls ciliogenesis in kidney cells. Knockdown of pVHL impeded the formation of cilia in mouse inner medullary collecting duct 3 kidney cells, whereas the expression of pVHL in VHL-negative renal cancer cells rescued the ciliogenesis defect. Using green fluorescent protein–tagged end-binding protein 1 to label microtubule plus ends, we found that pVHL does not affect the microtubule growth rate but is needed to orient the growth of microtubules toward the cell periphery, a prerequisite for the formation of cilia. Furthermore, pVHL interacts with the Par3–Par6–atypical PKC complex, suggesting a mechanism for linking polarity pathways to microtubule capture and ciliogenesis.
Filopodia formation mediated by receptor tyrosine kinase Ror2 is required for Wnt5a-induced cell migration
Authors: Nishita Michiru , Yoo Sa Kan , Nomachi Akira , Kani Shuichi , Sougawa Nagako , Ohta Yasutaka , Takada Shinji , Kikuchi Akira , Minami Yasuhiro
Published: November 2006

The receptor tyrosine kinase Ror2 plays important roles in developmental morphogenesis. It has recently been shown that Ror2 mediates Wnt5a-induced noncanonical Wnt signaling by activating the Wnt–JNK pathway and inhibiting the β-catenin–TCF pathway. However, the function of Ror2 in noncanonical Wnt signaling leading to cell migration is largely unknown. We show, using genetically different or manipulated cultured cells, that Ror2 is critical for Wnt5a-induced, but not Wnt3a-induced, cell migration. Ror2-mediated cell migration requires the extracellular cysteine-rich domain (CRD), which is the binding site for Wnt5a, and the cytoplasmic proline-rich domain (PRD) of Ror2. Furthermore, Ror2 can mediate filopodia formation via actin reorganization, irrespective of Wnt5a, and this Ror2-mediated filopodia formation requires the actin-binding protein filamin A, which associates with the PRD of Ror2. Intriguingly, disruption of filopodia formation by suppressing the expression of either Ror2 or filamin A inhibits Wnt5a-induced cell migration, indicating that Ror2-mediated filopodia formation is essential for Wnt5a-induced cell migration.
Plasma cell S1P1 expression determines secondary lymphoid organ retention versus bone marrow tropism
Authors: Kabashima Kenji , Haynes Nicole M. , Xu Ying , Nutt Stephen L. , Allende Maria L. , Proia Richard L. , Cyster Jason G.
Published: November 2006

After induction in secondary lymphoid organs, a subset of antibody-secreting cells (ASCs) homes to the bone marrow (BM) and contributes to long-term antibody production. The factors determining secondary lymphoid organ residence versus BM tropism have been unclear. Here we demonstrate that in mice treated with FTY720 or that lack sphingosine-1-phosphate (S1P) receptor-1 (S1P1) in B cells, IgG ASCs are induced and localize normally in secondary lymphoid organs but they are reduced in numbers in blood and BM. Many IgG ASCs home to BM on day 3 of the secondary response and day 3 splenic ASCs exhibit S1P responsiveness, whereas the cells remaining at day 5 are unable to respond. S1P1 mRNA abundance is higher in ASCs isolated from blood compared to spleen, whereas CXCR4 expression is lower. Blood ASCs also express higher amounts of Kruppel-like factor (KLF)2, a regulator of S1P1 gene expression. These findings establish an essential role for S1P1 in IgG plasma cell homing and they suggest that differential regulation of S1P1 expression in differentiating plasma cells may determine whether they remain in secondary lymphoid organs or home to BM.
Blinded Case-Control Study of the Relationship between Human Coronavirus NL63 and Kawasaki Syndrome
Authors: Dominguez Samuel R.  , Anderson Marsha S.  , Glodé Mary P.  , Robinson Christine C.  , Holmes Kathryn V. 
Published: November 2006

We conducted a blinded, case-control, retrospective study in pediatric patients hospitalized at The Children’s Hospital, Denver, Colorado, to determine whether human coronavirus (HCoV)–NL63 infection is associated with Kawasaki syndrome (KS). Over the course of a 7-month period, nasopharyngeal-wash samples from 2 (7.7%) of 26 consecutive children with KS and 4 (7.7%) of 52 matched control subjects tested positive for HCoV-NL63 by reverse transcription–polymerase chain reaction. These data suggest that, although HCoV-NL63 was circulating in children in our community during the time of the study, the prevalence of infection with HCoV-NL63 was not greater in patients with KS than in control subjects.
Relative Kazhdan–Lusztig cells
Authors: Geck Meinolf
Published: November 2006

In this paper, we study the Kazhdan–Lusztig cells of a Coxeter groupWWin a “relative” setting, with respect to a parabolic subgroupWI⊆WW_I \subseteq W. This relies on a factorization of the Kazhdan–Lusztig basis{Cw}\{\mathbf {C}_w\}of the corresponding (multi-parameter) Iwahori–Hecke algebra with respect toWIW_I. We obtain two applications to the “asymptotic case” in typeBnB_n, as introduced by Bonnafé and Iancu: we show that{Cw}\{\mathbf {C}_w\}is a “cellular basis” in the sense of Graham and Lehrer, and we construct an analogue of Lusztig’s canonical isomorphism from the Iwahori–Hecke algebra to the group algebra of the underlying Weyl group of typeBnB_n.
Transcriptome Analysis Reveals a Critical Role ofCHS7andCHS8Genes for Isoflavonoid Synthesis in Soybean Seeds
Authors: Dhaubhadel Sangeeta , Gijzen Mark , Moy Pat , Farhangkhoee Mana
Published: November 2006

We have used cDNA microarray analysis to examine changes in gene expression during embryo development in soybean (Glycine max) and to compare gene expression profiles of two soybean cultivars that differ in seed isoflavonoid content. The analysis identified 5,910 genes that were differentially expressed in both soybean cultivars grown at two different locations for two consecutive years in one of the five different stages of embryo development. An ANOVA analysis with P value < 0.05 and < 0.01 indicated that gene expression changes due to environmental factors are greater than those due to cultivar differences. Most changes in gene expression occurred at the stages when the embryos were at 30 or 70 d after pollination. A significantly larger fraction of genes (48.5%) was expressed throughout the development and showed little or no change in expression. Transcript accumulation for genes related to the biosynthesis of storage components in soybean embryos showed several unique temporal expressions. Expression patterns of several genes involved in isoflavonoid biosynthesis, such as Phenylalanine Ammonia-Lyase, Chalcone Synthase (CHS) 7, CHS8, and Isoflavone Synthase2, were higher at 70 d after pollination in both the cultivars. Thus, expression of these genes coincides with the onset of accumulation of isoflavonoids in the embryos. A comparative analysis of genes involved in isoflavonoid biosynthesis in RCAT Angora (high seed isoflavonoid cultivar) and Harovinton (low seed isoflavonoid cultivar) revealed that CHS7 and CHS8 were expressed at significantly greater level in RCAT Angora than in Harovinton. Our study provides a detailed transcriptome profiling of soybean embryos during development and indicates that differences in the level of seed isoflavonoids between these two cultivars could be as a result of differential expression of CHS7 and CHS8 during late stages of seed development.
MAIZEWALL. Database and Developmental Gene Expression Profiling of Cell Wall Biosynthesis and Assembly in Maize
Authors: Guillaumie Sabine , San-Clemente Hélène , Deswarte Caroline , Martinez Yves , Lapierre Catherine , Murigneux Alain , Barrière Yves , Pichon Magalie , Goffner Deborah
Published: November 2006

An extensive search for maize (Zea mays) genes involved in cell wall biosynthesis and assembly has been performed and 735 sequences have been centralized in a database, MAIZEWALL (http://www.polebio.scsv.ups-tlse.fr/MAIZEWALL). MAIZEWALL contains a bioinformatic analysis for each entry and gene expression data that are accessible via a user-friendly interface. A maize cell wall macroarray composed of a gene-specific tag for each entry was also constructed to monitor global cell wall-related gene expression in different organs and during internode development. By using this macroarray, we identified sets of genes that exhibit organ and internode-stage preferential expression profiles. These data provide a comprehensive fingerprint of cell wall-related gene expression throughout the maize plant. Moreover, an in-depth examination of genes involved in lignin biosynthesis coupled to biochemical and cytological data from different organs and stages of internode development has also been undertaken. These results allow us to trace spatially and developmentally regulated, putative preferential routes of monolignol biosynthesis involving specific gene family members and suggest that, although all of the gene families of the currently accepted monolignol biosynthetic pathway are conserved in maize, there are subtle differences in family size and a high degree of complexity in spatial expression patterns. These differences are in keeping with the diversity of lignified cell types throughout the maize plant.
Combining Expression and Comparative Evolutionary Analysis. TheCOBRAGene Family
Authors: Brady Siobhan M. , Song Shuang , Dhugga Kanwarpal S. , Rafalski J. Antoni , Benfey Philip N.
Published: November 2006

Plant cell shape is achieved through a combination of oriented cell division and cell expansion and is defined by the cell wall. One of the genes identified to influence cell expansion in the Arabidopsis (Arabidopsis thaliana) root is the COBRA (COB) gene that belongs to a multigene family. Three members of the AtCOB gene family have been shown to play a role in specific types of cell expansion or cell wall biosynthesis. Functional orthologs of one of these genes have been identified in maize (Zea mays) and rice (Oryza sativa; Schindelman et al., 2001; Li et al., 2003; Brown et al., 2005; Persson et al., 2005; Ching et al., 2006; Jones et al., 2006). We present the maize counterpart of the COB gene family and the COB gene superfamily phylogeny. Most of the genes belong to a family with two main clades as previously identified by analysis of the Arabidopsis family alone. Within these clades, however, clear differences between monocot and eudicot family members exist, and these are analyzed in the context of Type I and Type II cell walls in eudicots and monocots. In addition to changes at the sequence level, gene regulation of this family in a eudicot, Arabidopsis, and a monocot, maize, is also characterized. Gene expression is analyzed in a multivariate approach, using data from a number of sources, including massively parallel signature sequencing libraries, transcriptional reporter fusions, and microarray data. This analysis has revealed that the expression of Arabidopsis and maize COB gene family members is highly developmentally and spatially regulated at the tissue and cell type-specific level, that gene superfamily members show overlapping and unique expression patterns, and that only a subset of gene superfamily members act in response to environmental stimuli. Regulation of expression of the Arabidopsis COB gene family members has highly diversified in comparison to that of the maize COB gene superfamily members. We also identify BRITTLE STALK 2-LIKE 3 as a putative ortholog of AtCOB.
Modification of Leaf Apoplastic pH in Relation to Stomatal Sensitivity to Root-Sourced Abscisic Acid Signals
Authors: Jia Wensuo , Davies William John
Published: November 2006

The confocal microscope was used to determine the pH of the leaf apoplast and the pH of microvolumes of xylem sap. We quantified variation in leaf apoplast and sap pH in relation to changes in edaphic and atmospheric conditions that impacted on stomatal sensitivity to a root-sourced abscisic acid signal. Several plant species showed significant changes in the pH of both xylem sap and the apoplast of the shoot in response to environmental perturbation. Xylem sap leaving the root was generally more acidic than sap in the midrib and the apoplast of the leaf. Increasing the transpiration rate of both intact plants and detached plant parts resulted in more acidic leaf apoplast pHs. Experiments with inhibitors suggested that protons are removed from xylem sap as it moves up the plant, thereby alkalinizing the sap. The more rapid the transpiration rate and the shorter the time that the sap resided in the xylem/apoplastic pathway, the smaller the impact of proton removal on sap pH. Sap pH of sunflower (Helianthus annuus) and Commelina communis did not change significantly as soil dried, while pH of tomato (Lycopersicon esculentum) sap increased as water availability in the soil declined. Increasing the availability of nitrate to roots also significantly alkalinized the xylem sap of tomato plants. This nitrogen treatment had the effect of enhancing the sensitivity of the stomatal response to soil drying. These responses were interpreted as an effect of nitrate addition on sap pH and closure of stomata via an abscisic acid-based mechanism.
Characterization of thePreprotein and Amino Acid TransporterGene Family in Arabidopsis
Authors: Murcha Monika W. , Elhafez Dina , Lister Ryan , Tonti-Filippini Julian , Baumgartner Manuela , Philippar Katrin , Carrie Chris , Mokranjac Dejana , Soll Jürgen , Whelan James
Published: November 2006

Seventeen loci encode proteins of the preprotein and amino acid transporter family in Arabidopsis (Arabidopsis thaliana). Some of these genes have arisen from recent duplications and are not in annotated duplicated regions of the Arabidopsis genome. In comparison to a number of other eukaryotic organisms, this family of proteins has greatly expanded in plants, with 24 loci in rice (Oryza sativa). Most of the Arabidopsis and rice genes are orthologous, indicating expansion of this family before monocot and dicot divergence. In vitro protein uptake assays, in vivo green fluorescent protein tagging, and immunological analyses of selected proteins determined either mitochondrial or plastidic localization for 10 and six proteins, respectively. The protein encoded by At5g24650 is targeted to both mitochondria and chloroplasts and, to our knowledge, is the first membrane protein reported to be targeted to mitochondria and chloroplasts. Three genes encoded translocase of the inner mitochondrial membrane (TIM)17-like proteins, three TIM23-like proteins, and three outer envelope protein16-like proteins in Arabidopsis. The identity of Arabidopsis TIM22-like proteins is most likely a protein encoded by At3g10110/At1g18320, based on phylogenetic analysis, subcellular localization, and complementation of a yeast (Saccharomyces cerevisiae) mutant and coexpression analysis. The lack of a preprotein and amino acid transporter domain in some proteins, localization in mitochondria, plastids, or both, variation in gene structure, and the differences in expression profiles indicate that the function of this family has diverged in plants beyond roles in protein translocation.
Genetic Variation Suggests Interaction between Cold Acclimation and Metabolic Regulation of Leaf Senescence
Authors: Masclaux-Daubresse Céline , Purdy Sarah , Lemaitre Thomas , Pourtau Nathalie , Taconnat Ludivine , Renou Jean-Pierre , Wingler Astrid
Published: November 2006

The extent to which leaf senescence is induced by nitrogen deficiency or by sugar accumulation varies between natural accessions of Arabidopsis (Arabidopsis thaliana). Analysis of senescence in plants of the Bay-0 × Shahdara recombinant inbred line (RIL) population revealed a large variation in developmental senescence of the whole leaf rosette, which was in agreement with the extent to which glucose (Glc) induced senescence in the different lines. To determine the regulatory basis of genetic differences in the Glc response, we investigated changes in gene expression using Complete Arabidopsis Transcriptome MicroArray (CATMA) analysis. Genes whose regulation did not depend on the genetic background, as well as genes whose regulation was specific to individual RILs, were identified. In RIL 310, a line that does not show the typical senescence response to Glc, stress response genes, especially those responding to cold stress, were induced by Glc. We therefore tested whether cold acclimation delays senescence by reducing sugar sensitivity. In cold-acclimated plants, leaf senescence was severely delayed and Glc did not induce the typical senescence response. Together, our results suggest that cold acclimation extends rosette longevity by affecting metabolic regulation of senescence, thereby allowing vernalization-dependent plants to survive the winter period. The role of functional chloroplasts and of nitrogen and phosphate availability in this regulation is discussed.
Degradation of Oxidized Proteins by Autophagy during Oxidative Stress in Arabidopsis
Authors: Xiong Yan , Contento Anthony L. , Nguyen Phan Quang , Bassham Diane C.
Published: November 2006

Upon encountering oxidative stress, proteins are oxidized extensively by highly reactive and toxic reactive oxidative species, and these damaged, oxidized proteins need to be degraded rapidly and effectively. There are two major proteolytic systems for bulk degradation in eukaryotes, the proteasome and vacuolar autophagy. In mammalian cells, the 20S proteasome and a specific type of vacuolar autophagy, chaperone-mediated autophagy, are involved in the degradation of oxidized proteins in mild oxidative stress. However, little is known about how cells remove oxidized proteins when under severe oxidative stress. Using two macroautophagy markers, monodansylcadaverine and green fluorescent protein-AtATG8e, we here show that application of hydrogen peroxide or the reactive oxidative species inducer methyl viologen can induce macroautophagy in Arabidopsis (Arabidopsis thaliana) plants. Macroautophagy-defective RNAi-AtATG18a transgenic plants are more sensitive to methyl viologen treatment than wild-type plants and accumulate a higher level of oxidized proteins due to a lower degradation rate. In the presence of a vacuolar H+-ATPase inhibitor, concanamycin A, oxidized proteins were detected in the vacuole of wild-type root cells but not RNAi-AtATG18a root cells. Together, our results indicate that autophagy is involved in degrading oxidized proteins under oxidative stress conditions in Arabidopsis.
Credibility of Self‐Report for Ethnic‐Minority Pregnant Smokers1
Authors: Fischer Edward H. , Dornelas Ellen A. , Malchodi Carolyn S. , Oncken Cheryl A.
Published: November 2006

Two independent samples of pregnant smokers were interviewed about their cigarette smoking and were tested with biochemical markers at the beginning and end of their pregnancies. Participants were mainly unmarried, racial minorities (chiefly Hispanic), and residents of the inner city. Phi coefficients between self‐reported and chemical indicators ranged from .42 to .74. Contrary to expectations, the self‐report/biochemical‐measure correlations were higher at the end than at the beginning of the pregnancy term. The higher end‐of‐term correspondence between self‐report and chemical indicators likely reflected better reliability of the measures, when taken at term. The results are in accord with earlier research with other populations, indicating adequate validity for self‐reported smoking.
Personality and Dutch Emigrants' Reactions to Acculturation Strategies
Authors: Bakker Winny , Van Der Zee Karen , Van Oudenhoven Jan Pieter
Published: November 2006

This experimental questionnaire study examined individual differences in affective and normative reactions to acculturation strategies. A sample of 265 Dutch emigrants with a dual cultural background read scenarios describing the experiences of an emigrant. Eight (4 × 2) different scenario versions were developed, each referring to 1 of 4 acculturation strategies (Berry, 1997) and representing either the Frisian or the Dutch native culture. Participants reacted most positively to the integration strategy. There were no differences in reactions to Frisian or Dutch original culture. With respect to the influence of personality, as measured with the Multicultural Personality Questionnaire (van der Zee & van Oudenhoven, 2000), individuals high in flexibility responded more positively to the assimilation strategy than did individuals who scored low on this dimension.
Materialistic Values and Well‐Being Among Business Students: Further Evidence of Their Detrimental Effect1
Authors: Vansteenkiste Maarten , Duriez Bart , Simons Joke , Soenens Bart
Published: November 2006

According to an environmental‐match perspective regarding the content of values (Sagiv & Schwartz, 2000), extrinsic or materialistic values should positively predict well‐being in populations in which extrinsic values match the environmentally promoted values (e.g., among business students). However, other value researchers (Kasser & Ahuvia, 2002) disagree with these claims. Although the present study shows that business students ascribe higher importance to extrinsic values than do education students, the negative relation of extrinsic values with well‐being and the positive relation with internal distress and substance use was not moderated by the department to which students belonged. Finally, mediational analyses revealed that value orientations could account for the fact that business students report lower well‐being and higher substance use in comparison to education students.
Why Drug Testing in Elite Sport Does Not Work: Perceptual Deterrence Theory and the Role of Personal Moral Beliefs1
Authors: Strelan Peter , Boeckmann Robert J.
Published: November 2006

Performance‐enhancing drug use by elite athletes is a modern sporting and social concern. We applied a long‐overdue theoretical framework, perceptual deterrence, to predicting the banned drug‐use decisions of 116 elite Australian footballers and soccer players. The strongest influence on athletes' hypothetical decisions to use drugs was their personal moral beliefs and health concerns, each of which also mediated the relationship between drug testing and athletes' decisions to use banned substances. Drug testing had little influence on athletes' imagined drug use decisions, although there are athletes for whom legal sanctions are necessary. The results have important implications for the way in which authorities fund and frame future anti‐drug initiatives; particularly the relationship between drug testing and athletes' personal moral beliefs.
Attitudes Toward Divorce: Embeddedness and Outcomes in Personal Relationships
Authors: Riggio Heidi R. , Fite Jennifer E.
Published: November 2006

Divorce attitudes, attitude embeddedness, parental marital status and conflict, and personal relationship outcomes were examined in a sample of 289 undergraduate students. Results indicated that highly embedded divorce attitudes were more predictive of evaluations of divorce issues and relationship scenarios than were less embedded attitudes. Consistent with findings that divorce attitudes influence personal relationships (Amato & DeBoer, 2001), participants with embedded divorce attitudes reported greater conflict and influence of relationship partners. Recollections of high parental conflict were associated with greater relationship conflict; and individuals from high‐conflict intact families reported greater relationship closeness, conflict, and embedded divorce attitudes. Consequences of parental divorce and conflict for offspring divorce attitudes are discussed, as well as future research on divorce attitudes and their strength.
Directionality of the Association Between Social Support and Posttraumatic Stress Disorder: A Longitudinal Investigation1
Authors: King Daniel W. , Taft Casey , King Lynda A. , Hammond Charity , Stone Erika R.
Published: November 2006

This study examined the nature of the association between social support and posttraumatic stress disorder (PTSD) symptomatology among 2,249 male veterans of the 1990‐1991 Gulf War. Using structural equation modeling, a cross‐lagged panel analysis indicated a strong negative relationship between PTSD at Time 1 and social support at Time 2, while social support at Time 1 did not predict PTSD at Time 2. Findings suggest that, over time, interpersonal problems associated with PTSD may have a detrimental influence on the quality and quantity of available social support resources. It is recommended that greater focus be placed on the interpersonal skills of those suffering from PTSD.
Effects of Reward and Coercion for Transgression Compliance on Judgments of Responsibility and Recommended Punishment
Authors: Greitemeyer Tobias , Weiner Bernard
Published: November 2006

Previous research (Greitemeyer & Weiner, 2003) has demonstrated that compliance to commit a transgression for an anticipated reward as opposed to an anticipated punishment results in greater inferences of personal responsibility. The present studies extend these findings to a courtroom context in which punishment decisions are made. In Study 1, a nurse who administered a non‐approved drug was perceived as more responsible; and more severe punishment decisions were recommended, given compliance for an offered reward relative to a threatened punishment. These findings subsequently were replicated while varying the consequences of the drug administration (Study 2) and employing an antisocial scenario (Study 3). Legal theory, field theory, and prospect theory are discussed as possible explanations for these phenomena.
Chronic hepatitis B: current epidemiology in the Americas and implications for management
Authors: Gish R. G. , Gadano A. C.
Published: November 2006

Summary.  Hepatitis B virus (HBV) remains a serious health threat in many parts of the world. Although its prevalence is lower in the Americas than in Asia, Africa and the Middle East, it is responsible for significant morbidity and mortality in North, Central and South America. There is a nonuniform pattern of distribution throughout this region, with HBV prevalence related to geographical, social and cultural factors that predispose certain individuals to infection. This report details the incidence, modes of viral transmission of hepatitis B in the Americas and clinical course of disease in different regions of the Americas. Additionally, the implications for management focusing on issues predominant in high‐risk populations are presented.
Development changes of cuticular hydrocarbons inChrysomya rufifacieslarvae: potential for determining larval age
Authors: ZHU G. H. , YE G. Y. , HU C. , XU X. H. , LI K.
Published: November 2006

AbstractAge determination is the basis of determining the postmortem interval using necrophagous fly larvae. To explore the potential of using cuticular hydrocarbons for determining the ages of fly larvae, changes of cuticular hydrocarbons in developing larvae ofChrysomya rufifacies(Macquart) (Diptera: Calliphoridae) were investigated using gas chromatography with flame‐ionization detection and gas chromatography‐mass spectrometry. This study showed that the larvae produced cuticular hydrocarbons typical of insects. Most of the hydrocarbons identified were alkanes with the carbon chain length of 21–31, plus six kinds of alkenes. The hydrocarbon composition of the larvae correlated with age. The statistical results showed that simple peak ratios ofn‐C29 divided by another eight selected peaks increased significantly with age; their relationships with age could be modelled using exponential or power functions withR2close to or > 0.80. These results suggest that cuticular hydrocarbon composition is a useful indicator for determining the age of larvalC. rufifacies, especially for post‐feeding larvae, which are difficult to differentiate by morphology.
Phylogeography of the Western Lyresnake (Trimorphodon biscutatus): testing aridland biogeographical hypotheses across the Nearctic–Neotropical transition
Authors: DEVITT THOMAS J.
Published: November 2006

The Western Lyresnake (Trimorphodon biscutatus) is a widespread, polytypic taxon inhabiting arid regions from the warm deserts of the southwestern United States southward along the Pacific versant of Mexico to the tropical deciduous forests of Mesoamerica. This broadly distributed species provides a unique opportunity to evaluate a priori biogeographical hypotheses spanning two major distinct biogeographical realms (the Nearctic and Neotropical) that are usually treated separately in phylogeographical analyses. I investigated the phylogeography ofT. biscutatususing maximum likelihood and Bayesian phylogenetic analysis of mitochondrial DNA (mtDNA) from across this species’ range. Phylogenetic analyses recovered five well‐supported clades whose boundaries are concordant with existing geographical barriers, a pattern consistent with a model of vicariant allopatric divergence. Assuming a vicariance model, divergence times between mitochondrial lineages were estimated using Bayesian relaxed molecular clock methods calibrated using geological information from putative vicariant events. Divergence time point estimates were bounded by broad confidence intervals, and thus these highly conservative estimates should be considered tentative hypotheses at best. Comparison of mtDNA lineages and taxa traditionally recognized as subspecies based on morphology suggest this taxon is comprised of multiple independent lineages at various stages of divergence, ranging from putative secondary contact and hybridization to sympatry of ‘subspecies’.
When supercolonies collide: territorial aggression in an invasive and unicolonial social insect
Authors: THOMAS MELISSA L. , PAYNE‐MAKRISÂ CHRISTINE M. , SUAREZ ANDREW V. , TSUTSUI NEIL D. , HOLWAY DAVID A.
Published: November 2006

Some species of ants possess an unusual form of social organization in which aggression among nests is absent. This type of social organization, called unicoloniality, has been studied in only a handful of species and its evolutionary origins remain unclear. To date, no study has examined behavioural and genetic patterns at points of contact between the massive supercolonies that characterize unicoloniality. Since interactions at territory boundaries influence the costs of aggression and the likelihood of gene flow, such data may illuminate how supercolonies are formed and maintained. Here we provide field data on intraspecific territoriality for a widespread and invasive unicolonial social insect, the Argentine ant (Linepithema humile). We observed abrupt and well‐defined behavioural boundaries at 16 contact zones between three different pairs of supercolonies. We visited nine of these zones weekly during a six‐month period and observed consistent and intense intercolony aggression that resulted in variable, but often large, levels of worker mortality. Microsatellite variation along six transects across territory borders showed that FST values were lower within supercolonies (0.08 ± 0.01 (mean ± SE)) than between supercolonies (0.29 ± 0.01) and that this disparity was especially strong right at territory borders, despite direct and prolonged contact between the supercolonies. Matrix correspondence tests confirmed that levels of aggression and genetic differentiation were significantly correlated, but no relationship existed between geographic distance and either intraspecific aggression or genetic differentiation. Patterns of FST variation indicated high levels of gene flow within supercolonies, but little to no gene flow between them. Overall, these findings are inconsistent with a model of relaxed ecological constraints leading to colony fusion and suggest that environmentally derived cues are not the prime determined of nestmate recognition in field populations of Argentine ants.
Comprehensive genetic analyses reveal evolutionary distinction of a mouse (Zapus hudsonius preblei) proposed for delisting from the US Endangered Species Act
Authors: KING TIM L. , SWITZER JOHN F. , MORRISON CHERYL L. , EACKLES MICHAEL S. , YOUNG COLLEEN C. , LUBINSKI BARBARA A. , CRYAN PAUL
Published: November 2006

Zapus hudsonius preblei, listed as threatened under the US Endangered Species Act (ESA), is one of 12 recognized subspecies of meadow jumping mice found in North America. Recent morphometric and phylogenetic comparisons amongZ. h. prebleiand neighbouring conspecifics questioned the taxonomic status of selected subspecies, resulting in a proposal to delist theZ. h. prebleifrom the ESA. We present additional analyses of the phylogeographic structure withinZ. hudsoniusthat calls into question previously published data (and conclusions) and confirms the original taxonomic designations. A survey of 21 microsatellite DNA loci and 1380 base pairs from two mitochondrial DNA (mtDNA) regions (control region and cytochromeb) revealed that eachZ. hudsoniussubspecies is genetically distinct. These data do not support the null hypothesis of a homogeneous gene pool among the five subspecies found within the southwestern portion of the species’ range. The magnitude of the observed differentiation was considerable and supported by significant findings for nearly every statistical comparison made, regardless of the genome or the taxa under consideration. Structuring of nuclear multilocus genotypes and subspecies‐specific mtDNA haplotypes corresponded directly with the disjunct distributions of the subspecies investigated. Given the level of correspondence between the observed genetic population structure and previously proposed taxonomic classification of subspecies (based on the geographic separation and surveys of morphological variation), we conclude that the nominal subspecies surveyed in this study do not warrant synonymy, as has been proposed forZ. h. preblei,Z. h. campestris, andZ. h. intermedius.
Diversity and natural hybridization in a highly endemic species of Petunia (Solanaceae): a molecular and ecological analysis
Authors: LORENZ‐LEMKE ALINE P. , MÄDER GERALDO , MUSCHNER VALÉRIA C. , STEHMANN JOÃO R. , BONATTO SANDRO L. , SALZANO FRANCISCO M. , FREITAS LORETA B.
Published: November 2006

Intrinsic reproductive barriers among the species of Petunia are weak and genetic isolation is obtained mainly by geographical separation and ecological diversification. The Serra do Sudeste region in the extreme south of Brazil is one of the centres of diversity of this genus and is characterized by the presence of species with different pollination syndromes. Petunia exserta is known only from four sandstone towers in a restricted area of this region (about 500 km2) and is characterized by its differentiated habitat (shelters in the sandstone towers) and by its floral characteristics adapted to ornithophily. In towers where this species is sympatric with the sphingophilous Petunia axillaris, phylogenetically close to P. exserta, we found plants with intermediate floral morphology, suggesting hybridization between them. To test this hypothesis and to better understand its consequences we analysed the sequences of the plastid trnH‐psbA, trnS‐trnG and psbB‐psbH intergenic spacers in 121 individuals sampled all over the P. exserta distribution. The joint analysis of the three markers revealed 13 haplotypes and the network showed two main genetic clades, which probably represent the original gene pool of the two species in the region. In general, individuals of a given population presented the same haplotype, independently of phenotype, corroborating the hybridization hypothesis. Field observations suggest that hummingbirds are responsible for the interspecific gene flow. Analysis of molecular variance revealed high interpopulational diversity among the towers. The low gene flow between populations is possibly related to the autochoric seed dispersion system.