bluuebunny/crossref_metadata_2025 huggingface dataset:
Tryptophan hydroxylase 1 gene haplotypes modify the effect of a hostile childhood environment on adulthood harm avoidance
Authors: Keltikangas‐Järvinen L. , Puttonen Sampsa , Kivimäki Mika , Elovainio Marko , Rontu Riikka , Lehtimäki Terho
Published: July 2006

We conducted a series of tests to determine whether there is any association between tryptophan hydroxylase 1 (TPH1) and temperament in adulthood. In addition to testing for main effects, we investigated whether TPH1 gene variation modifies the influence of childhood environment on temperament in adulthood. The subjects were 341 healthy adults whose childhood environment was assessed by their mothers in 1980 and who self‐rated their temperaments twice, in 1997 and 2001. We found no association between the TPH1 gene and temperament; however, among women, the TPH1 gene modified a relationship between adverse childhood environment and harm avoidance in adulthood. This finding was confirmed in the same sample in another test setting 4 years later. The presence of the A/A haplotype of the TPH1 intron 7 A218A and A779C polymorphism predicted a high level of adulthood harm avoidance in the presence of a hostile childhood environment as defined in terms of emotional rejection, maternal neglect and harsh and inconsistent discipline. In addition, the findings suggest a gene–environment correlation for novelty seeking in men.
Dopamine levels modulate the updating of tastant values
Authors: Costa R. M. , Gutierrez R. , De Araujo I. E. , Coelho M. R. P. , Kloth A. D. , Gainetdinov R. R. , Caron M. G. , Nicolelis M. A. L. , Simon S. A.
Published: July 2006

To survive, animals must constantly update the internal value of stimuli they encounter; a process referred to as incentive learning. Although there have been many studies investigating whether dopamine is necessary for reward, or for the association between stimuli and actions with rewards, less is known about the role of dopamine in the updating of the internal value of stimuli per se. We used a single‐bottle forced‐choice task to investigate the role of dopamine in learning the value of tastants. We show that dopamine transporter knock‐out mice (DAT‐KO), which have constitutively elevated dopamine levels, develop a more positive bias towards a hedonically positive tastant (sucrose 400 mM) than their wild‐type littermates. Furthermore, when compared to wild‐type littermates, DAT‐KO mice develop a less negative bias towards a hedonically negative tastant (quinine HCl 10 mM). Importantly, these effects develop with training, because at the onset of training DAT‐KO and wild‐type mice display similar biases towards sucrose and quinine. These data suggest that dopamine levels can modulate the updating of tastant values, a finding with implications for understanding sensory‐specific motivation and reward seeking.
TOWARD A SEMIOTIC THEORY OF CHOICE AND OF LEARNING
Authors: Stables Andrew , Gough Stephen
Published: July 2006

Abstract In this essay, Andrew Stables and Stephen Gough explore some of the implications for educational policy and practice of a view of living (and, therefore, of learning) as semiotic engagement. Such a view, Stables and Gough argue, has the potential to displace or circumvent essentially Cartesian models currently dominant within learning theory (cognitivism and responses to it) and within neoclassical economics (rational choice and responses to it). It thus enables synergies between theories of learning and of economic behavior, allowing for greater consistency in thinking about (but not necessarily prescribing for) both educational policy and provision, on the one hand, and curriculum and pedagogy, on the other. In addition, the authors claim that giving semiotics a foundational role in educational thinking provides a basis for the broader development of liberal political thought within a postmodern cultural context.
Calpain involvement in the remodeling of cytoskeletal anchorage complexes
Authors: Lebart Marie‐Christine , Benyamin Yves
Published: July 2006

Cells offer different types of cytoskeletal anchorages: transitory structures such as focal contacts and perennial ones such as the sarcomeric cytoskeleton of muscle cells. The turnover of these structures is controlled with different timing by a family of cysteine proteases activated by calcium, the calpains. The large number of potential substrates present in each of these structures imposes fine tuning of the activity of the proteases to avoid excessive action. This phenomenon is thus guaranteed by various types of regulation, ranging from a relatively high calcium concentration necessary for activation, phosphorylation of substrates or the proteases themselves with either a favorable or inhibitory effect, possible intervention of phospholipids, and the presence of a specific inhibitor and its possible degradation before activation. Finally, formation of multiprotein complexes containing calpains offers a new method of regulation.
Plasmodium falciparum DNA helicase 60
Authors: Pradhan Arun , Tuteja Renu
Published: July 2006

Helicases are ubiquitous enzymes that play important roles in all types of DNA transaction in the cells. Recently we have reported the characterization of the first DEAD‐box helicase [Plasmodium falciparum DNA helicase 60 (PfDH60)] from Plasmodium falciparum and have shown that it is a unique, dual bipolar helicase expressed in a stage‐specific manner. In this study, we show the further characterization of PfDH60. For analyzing the significance of this enzyme in parasite growth, we studied the effect of dsRNA and specific antibodies on growth of the parasite. The studies indicate that the parasite cultures treated with PfDH60 dsRNA exhibited ∼ 50% growth inhibition when compared with either untreated cultures or cultures treated with unrelated dsRNA. It was interesting to note that purified immunoglobulins against PfDH60 induced ∼ 62% inhibition of in vitro growth of P. falciparum and that this inhibitory effect was associated with morphologic damage to the parasite. DNA‐interacting compounds inhibit DNA helicase and ssDNA‐dependent ATPase activities of PfDH60. Of various compounds tested, only actinomycin, daunorubicin, ethidium bromide, netropsin and nogalamycin were able to inhibit the enzyme activities of PfDH60, with apparent IC50 values for helicase inhibition of 0.8, 0.3, 2.0, 1.2 and 1.5 µm, respectively. It may be proposed that these compounds form a complex with DNA and specifically inhibit helicases due to obstruction in the translocation of the enzyme. These compounds also inhibited parasite growth in culture. This is the first study to show inhibition of growth of the parasite by the dsRNA of a helicase, and most probably this is due to interference with cognate mRNA expression.
A kinetic study of a ternary cycle between adenine nucleotides
Authors: Valero Edelmira , Varón Ramón , García‐Carmona Francisco
Published: July 2006

In the present paper, a kinetic study is made of the behavior of a moiety‐conserved ternary cycle between the adenine nucleotides. The system contains the enzymes S‐acetyl coenzyme A synthetase, adenylate kinase and pyruvate kinase, and converts ATP into AMP, then into ADP and finally back to ATP. l‐Lactate dehydrogenase is added to the system to enable continuous monitoring of the progress of the reaction. The cycle cannot work when the only recycling substrate in the reaction medium is AMP. A mathematical model is proposed whose kinetic behavior has been analyzed both numerically by integration of the nonlinear differential equations describing the kinetics of the reactions involved, and analytically under steady‐state conditions, with good agreement with the experimental results being obtained. The data obtained showed that there is a threshold value of the S‐acetyl coenzyme A synthetase/adenylate kinase ratio, above which the cycle stops because all the recycling substrate has been accumulated as AMP, never reaching the steady state. In addition, the concept of adenylate energy charge has been applied to the system, obtaining the enabled values of the rate constants for a fixed adenylate energy charge value and vice versa.
Agrobacterium tumefaciens type II NADH dehydrogenase
Authors: Bernard Laetitia , Desplats Carine , Mus Florence , Cuiné Stéphan , Cournac Laurent , Peltier Gilles
Published: July 2006

Type II NADH dehydrogenases (NDH‐2) are monomeric enzymes that catalyse quinone reduction and allow electrons to enter the respiratory chain in different organisms including higher plant mitochondria, bacteria and yeasts. In this study, an Agrobacterium tumefaciens gene encoding a putative alternative NADH dehydrogenase (AtuNDH‐2) was isolated and expressed in Escherichia coli as a (His)6‐tagged protein. The purified 46 kDa protein contains FAD as a prosthetic group and oxidizes both NADH and NADPH with similar Vmax values, but with a much higher affinity for NADH than for NADPH. AtuNDH‐2 complements the growth (on a minimal medium) of an E. coli mutant strain deficient in both NDH‐1 and NDH‐2, and is shown to supply electrons to the respiratory chain when incubated with bacterial membranes prepared from this mutant. By measuring photosystem II chlorophyll fluorescence on thylakoid membranes prepared from the green alga Chlamydomonas reinhardtii, we show that AtuNDH‐2 is able to stimulate NADH‐dependent reduction of the plastoquinone pool. We discuss the possibility of using heterologous expression of NDH‐2 enzymes to improve nonphotochemical reduction of plastoquinones and H2 production in C. reinhardtii.
Water Channels Are Involved in Stomatal Oscillations Encoded by Parameter‐Specific Cytosolic Calcium Oscillations
Authors: Yang Hui‐Min , Zhang Xiao‐Yan , Wang Gen‐Xuan , Zhang Jian‐Hua
Published: July 2006

Earlier studies have shown that various stimuli can induce specific cytosolic calcium ([Ca2+]cyt) oscillations in guard cells and various oscillations in stomatal apertures. Exactly how [Ca2+]cyt oscillation signaling functions in stomatal oscillation is not known. In the present study, the epidermis of broad bean (Vicia faba L.) was used and a rapid ion‐exchange treatment with two shifting buffers differing in K+ and Ca2+ concentrations was applied. The treatment for five transients at a 10‐min transient period induced clear and regular stomatal oscillation. However, for other transient numbers and periods, the treatments induced some irregular oscillations or even no obvious oscillations in stomatal aperture. The results indicate that stomatal oscillation is encoded by parameter‐specific [Ca2+]cyt oscillation: the parameters of [Ca2+]cyt oscillation affected the occurrence rate and the parameters of stomatal oscillation. The water channel inhibitor HgCl2 completely inhibited stomatal oscillation and the inhibitory effect could be partially reversed by β‐mercaptoethanol (an agent capable of reversing water channel inhibition by HgCl2). Other inhibitory treatments against ion transport (i.e. the application of LaCl3, EGTA, or tetraethylammonium chloride (TEACI)) weakly impaired stomatal oscillation when the compounds were added after rapid ion‐exchange treatment. If these compounds were added before rapid‐ion exchange treatment, the inhibitory effect was much more apparent (except in the case of TEACI). The results of the present study suggest that water channels are involved in stomatal oscillation as a downstream element of [Ca2+]cyt oscillation signaling.

(Managing editor: Wei Wang)
Isolation and Characterization of GmSTY1, a Novel Gene Encoding a Dual‐Specificity Protein Kinase in Soybean (Glycine max L.)
Authors: Xu Zhao‐Shi , Ma You‐Zhi , Cheng Xian‐Guo , Cao Li‐Xia , Li Lian‐Cheng , Chen Ming
Published: July 2006

Phosphorylation of protein kinases has profound effects on their activity and interaction with other proteins. Tyrosine phosphorylation was reported to be involved in various physiological processes in plants; however, no typical receptor tyrosine kinase has been isolated from plants thus far. Dual‐specificity kinases are potentially responsible for the phosphorylation of both tyrosine and serine/threonine of target proteins. A cDNA clone encoding a putative dual‐specificity protein kinase was isolated by screening the cDNA GAL4 activation domain (AD) fusion library of soybean (Glycine max L.), and its entire length was obtained using 5′‐rapid amplification of cDNA ends. The predicted polypeptide of 330 amino acid residues, designated as GmSTY1, contains all 11 conserved subdomains, which share common characteristics with both the serine/threonine and tyrosine protein kinases reported thus far. In addition, three potential AM inked glycosylation sites (NXS/T), as well as phosphorylation motifs (SXXXS/T), were observed, suggesting that GmSTY1 may be post‐translationally modified. Furthermore, a potential N‐myristoylation motif (MGARCSK) was found, suggesting that the GmSTY1 protein could associate with membranes in vivo. Southern blotting analysis revealed a single‐copy of GmSTY1 in the genome. Northern blotting analysis showed that this gene was upregulated by drought and salt treatment in a time‐dependent manner; however, exogenous abscisic acid (ABA) could not significantly affect the mRNA accumulation of GmSTY1. Interestingly, the transcript of this gene was remarkably downregulated by cold treatment during the early stages of the response, but upregulated later. These results indicate that the protein kinase was possibly regulated by abiotic stresses in an ABA‐independent pathway.

(Managing editor: Li‐Hui Zhao)
Application of Non‐invasive Microsensing System to Simultaneously Measure Both H+ and O2 Fluxes Around the Pollen Tube
Authors: Xu Yue , Sun Tong , Yin Li‐Ping
Published: July 2006

Various ionic and molecular activities in the extracellular environment are vital to plant cell physiological processes. A noninvasive microsensing system (NMS) based on either the scanning ion‐selective electrode technique (SIET) or the scanning polarographic electrode technique (SPET) is able to obtain information regarding the transportation of various ions/molecules in intact samples under normal physiological conditions. The two‐probe simultaneous test system (2STS) is an integrated system composed of SIET, SPET, and a Xu‐Kunkel sampling protocol. In the present study, 2STS was able to simultaneously measure fluxes of H+ and O2 of the lily (Lilium longiflorum Thunb. cv. Ace) pollen tube while avoiding interference between the two probes. The results indicate that the proton fluxes were effluxes, whereas the oxygen fluxes were influxes, and they were closely correlated to each other surrounding the constitutive alkaline band region. Specifically, when the proton effluxes increased, the oxygen influxes also increased. Therefore, the hypothesis of condensed active mitochondria existing in the alkalized area of the pollen tube proposed by Hepler's group is supported.

(Managing editor: Wei Wang)
Pollen Morphology of Tundra Shrubs and Submarginal Plants from Barrow, Alaska
Authors: Tang Ling‐Yu , Zhang Xiao‐Ping , Shao Jian‐Wen , Zhou Zhong‐Ze , Zhang Qing‐Song
Published: July 2006

Investigation of plant morphological features, pollen, and habitat have been made for two shrub species from Barrow, Alaska, namely Dryas integrifolia M. Vahl and Salix rotundifolia Trautv., both of which are endemic to the Arctic floristic area. The former species has small lanceolate or plate leaves, whereas the latter has rounded leaves with distinct veins, rich in vitamin C. Both have dwarf and sprawling habits. Pollen studies showed that the pollen grains of the two species are spheroidal to sub‐spheroidal or prolate. The type of aperture was tricolporate; pollen size 26.3–31.3 μm; ornamentation finely reticulate under a light microscope (LM) and striate‐reticulate under a scanning electron microscope (SEM) for D. integrafolia and finely reticulate under the LM and SEM for S. rotundifolia. Comparisons were made between the pollen from the same species from Arctic collections with those from China and Japan. Investigation of pollen morphology of tundra plants can provide significant data for comparative studies of fossil pollen and for the reconstruction of paleovegetation and paleoclimate in the Barrow area.

(Managing editor: Ya‐Qin Han)
The Territorial Dimension of CAP and Spatial Cohesion
Authors: Dax Thomas
Published: July 2006

Since the start of the CAP reform in the 1990s the demand for an increase of rural development measures has been intensified. However, up to now no comprehensive assessment of the territorial impacts of the CAP has been achieved. This article summarises the main findings of a recent study which was carried out under the European Union's ESPON programme on this issue. The regional analysis suggests that, at present, the CAP is not contributing towards the goal of more balanced and sustainable development across European territory. This finding is both valid for the more “traditional” CAP (Pillar 1) and the Rural Development measures, referred to as Second Pillar measures, indicating the emerging priority for these types of instruments. Yet, the great variation in the RDP priorities and implementation in the Member States underscore the wide scope for taking account of the spatial dimension more explicitly. In addition, the numerous best practice examples and the political support for RD action point to the untapped potential of local activities in rural areas. Strengthening the link to the spatial cohesion objectives is therefore a prerequisite for securing support by European citizens for future CAP payments.
Effect of Ozone on Postharvest Quality of Persimmon
Authors: Salvador Alejandra , Abad Isabel , Arnal Lucía , Martínez‐Jávega J.M.
Published: July 2006

ABSTRACT:  The effect of gaseous ozone exposure on the quality of persimmon picked at 2 different harvest dates was evaluated. Fruit from both harvests were continuously exposed to 0.15 ppm (vol/vol) of ozone for 30 d at 15 °C, 90% relative humidity (RH). Then, fruit were submitted to astringency removal treatment (24 h at 20 °C, 98% CO2) and stored for 7 d at 20 °C (90% RH) in order to simulate shelf‐life period. The most important disorder was flesh softening, which took place when fruit were transferred from 15 °C to shelf‐life conditions. In the 2nd harvest, where the fruit were harvested with lower firmness, ozone maintained firmness over commercial limits even after 30 d at 15 °C plus shelf‐life. Ozone‐treated fruit showed the highest values of weight loss, coinciding with the maximum electrolyte leakage (EL) percentage. Ozone did not affect color index (CI), ethanol, total soluble solids (TSS), or pH. Unremarkable differences in acetaldehyde were observed between fruit submitted to ozone treatment and control fruit. No phytotoxic injuries in tissues were observed in ozone‐treated fruit.
Whey Protein Coating Efficiency on Mechanically Roughened Hydrophobic Peanut Surfaces
Authors: Lin S.‐Y. , Krochta J.M.
Published: July 2006

ABSTRACT:  Mechanical roughening of commercially blanched‐and‐roasted peanuts efficiently improved whey protein coating efficiency. However, increased coating coverage varied significantly among peanuts, likely due to variable change of peanut surfaces during commercial processing and storage before coating. Coating efficiency was further improved and was more consistent on mechanically roughened freshly blanched‐and‐roasted peanuts compared to the commercially blanched‐and‐roasted peanuts. The improved coating efficiency without large variation on mechanically roughened freshly blanched‐and‐roasted peanuts may be the result of avoiding the re‐formation of a waxy cuticle layer on peanut surfaces, which occurs during storage between commercial blanching/roasting process and the coating application. Scanning electron microscope (SEM) micrographs of treated peanuts confirmed the effect of roughening, as well as disruption of the parenchyma cell structure of peanuts and the creation of channels that could allow oil migration to the peanut surface and subsequent formation of a waxy layer with long enough storage.
Antioxidant Activity of Liquid‐State Fermentation Products of Monascus pilosus Grown in Garlic‐Containing Medium
Authors: Kuo Chia‐Feng , Wang Tsu‐Shing , Yang Pei‐Lin , Jao Yueh‐Chuan , Lin Wun‐Yuan
Published: July 2006

ABSTRACT:  To evaluate the effect of garlic‐containing medium on the antioxidant activity of liquid‐state fermentation products of Monascus spp., antioxidant activity of garlic extract (GA), extract from mycelia of Monascus pilosus mutant submerged culture (MP), extract from mycelia of M. pilosus mutant submerged garlic‐containing culture (MPG), and growth substrate of M. pilosus mutant submerged garlic‐containing culture (SMPG) was evaluated by various antioxidant assays, including DPPH (1,1‐diphenyl‐2‐picryl‐hydrazyl), superoxide‐ and hydrogen peroxide‐scavenging assays, lipid peroxidation assay, and metal‐binding assay as well as ethidium bromide fluorescence‐binding assay. The results showed that radical‐scavenging, iron‐chelating, and DNA‐protection activities of GA were significantly higher than MP; however, after culturing in garlic‐containing medium, the antioxidant activities of M. pilosus fermentation products MPG and SMPG were significantly increased but not more than GA. The results imply that addition of garlic paste into culture medium raised the nutritive quality of M. pilosus fermentation products by increasing antioxidant activity.
Comparative Study of Quality Changes Occurring on Dehydration and Rehydration of Cooked Chickpeas (Cicer Arietinum L.) Subjected to Combined Microwave–Convective and Convective Hot Air Dehydration
Authors: Gowen A.A. , Abu‐Ghannam N. , Frias J.M. , Barat J.M. , Andres A.M. , Oliveira J.C.
Published: July 2006

ABSTRACT:  Convective hot air dehydration (100 °C) of cooked chickpeas was compared with the combination of microwave–convective hot air dehydration, in terms of microstructure, density, color, texture, dehydration, and rehydration. In the combined drying experiments, 2 levels of microwave power (100 W and 200 W) were investigated, combined continuously with convective air drying at 100 °C. Compared with convective hot air drying, combination drying led to a considerable reduction in dehydration time. Combination drying also improved the porosity of the finished dehydrated product, leading to faster rehydration kinetics. Cryogenic scanning electron microscopy micrographs showed that chickpeas subjected to combined drying experienced less shrinkage than those dried by convective hot air. Combination drying at the higher (200 W) level produced a darker (P < 0.05) rehydrated product with significantly lower relative rehydrated moisture content (P < 0.05) when compared with the lower (100 W) level of combination drying.
Tenderizing Effect of High Hydrostatic Pressure on Bovine Intramuscular Connective Tissue
Authors: Ichinoseki S. , Nishiumi T. , Suzuki A.
Published: July 2006

ABSTRACT:  The effect of high‐pressure treatment on bovine intramuscular connective tissue was investigated under various pressures (0.1 to 500 MPa) at 8 °C for 5 min. Shear force value, heat solubility of collagen, and structural changes of pressurized intramuscular connective tissues were evaluated. High hydrostatic pressure tenderized bovine intramuscular connective tissue as well as meat. The heat solubility of collagen increased (P < 0.05) with high pressure, which indicates a reduction of collagen thermal stability. However, high pressure could not degrade collagen molecules by sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis. Collagen‐derived peptide analysis also suggested that high pressure could not degrade the molecular structure of collagen, but could dissociate the collagen fibers or fibrils into fibrils or molecules. Histological study showed that high pressure induced structural weakening of intramuscular connective tissue, especially perimysium.
Sensory and Nutritional Quality of Dehydrated Potato Flakes in Long‐Term Storage
Authors: Neilson Andrew P. , Pahulu Heather F. , Ogden Lynn V. , Pike Oscar A.
Published: July 2006

ABSTRACT:  The sensory and nutritional quality of dehydrated potato flakes packaged in nr 10 cans held at ambient temperatures up to 30 y was studied. Thirteen samples of dehydrated potato flakes were obtained from donors. A consumer panel evaluated reconstituted product for appearance, aroma, texture, flavor, and overall acceptability using a 9‐point hedonic scale. Overall acceptability hedonic scores ranged from 3.7 to 6.6 and declined significantly over time. Sensory shelf‐life, based on a cutoff of 80% of initial overall acceptability, was 16 y. Vitamin C levels remained constant over storage time. Headspace hexanal concentrations ranged from 0 to 2.09 μg/g. There was no significant correlation between headspace hexanal of dry flakes and hedonic scores of reconstituted product. Dehydrated potato flakes appear to retain sufficient quality over time to warrant consideration for long‐term storage purposes.
Physical and Mechanical Properties of Pea Starch Edible Films Containing Beeswax Emulsions
Authors: Han J.H. , Seo G.H. , Park I.M. , Kim G.N. , Lee D.S.
Published: July 2006

ABSTRACT:  Hydrophobic beeswax emulsions were incorporated into hydrophilic starch films to modify physical, mechanical, and thermal properties of the films. Beeswax was added in the film‐forming solution of high‐amylose pea starch (35% to 40% amylose w/w) at the level of 0%, 10%, 20%, 30%, and 40% w/w of starch with glycerol as a plasticizer (40/60 of glycerol/starch). Addition of beeswax affected mechanical properties, significantly reducing tensile strength and elongation and increasing elastic modulus. Beeswax addition decreased water vapor permeability and increased oxygen permeability. However, the addition of hydrophobic wax particles in starch films marginally affected these physical properties below 30% beeswax in the films. Beeswax addition at the 40% concentration formed amylose–lipid complex that caused the dramatic changes of physical and thermal properties of the films.
Elucidating Factors Affecting Floatation of Fish Ball
Authors: Kok T.N. , Park J.W.
Published: July 2006

ABSTRACT:  Factors affecting floatation of fish ball in water were investigated. The density of threadfin bream (TB) surimi paste significantly decreased (P < 0.05) as moisture content, temperature, or salt concentration increased. The ability of surimi paste to float or sink in water was observed according to changes in density. In gel texture measurement, when surimi was thawed for 1 h before chopping at 5 °C with 2% salt, the highest breaking force and deformation values were obtained. Apparent viscosity of surimi paste decreased as moisture content increased or salt concentration increased, and chopping temperature decreased. Setting gels in salt solution (5 or 10%) significantly reduced (P < 0.05) stickiness, which is the tendency to stick to one another.
Oxygen sensing by mitochondria at complex III: the paradox of increased reactive oxygen species during hypoxia
Authors: Guzy Robert D. , Schumacker Paul T.
Published: July 2006

All eukaryotic cells utilize oxidative phosphorylation to maintain their high‐energy phosphate stores. Mitochondrial oxygen consumption is required for ATP generation, and cell survival is threatened when cells are deprived of O2. Consequently, all cells have the ability to sense O2, and to activate adaptive processes that will enhance the likelihood of survival in anticipation that oxygen availability might become limiting. Mitochondria have long been considered a likely site of oxygen sensing, and we propose that the electron transport chain acts as an O2 sensor by releasing reactive oxygen species (ROS) in response to hypoxia. The ROS released during hypoxia act as signalling agents that trigger diverse functional responses, including activation of gene expression through the stabilization of the transcription factor hypoxia‐inducible factor (HIF)‐α. The primary site of ROS production during hypoxia appears to be complex III. The paradoxical increase in ROS production during hypoxia may be explained by an effect of O2 within the mitochondrial inner membrane on: (a) the lifetime of the ubisemiquinone radical in complex III; (b) the relative release of mitochondrial ROS towards the matrix compartment versus the intermembrane space; or (c) the ability of O2 to access the ubisemiquinone radical in complex III. In summary, the process of oxygen sensing is of fundamental importance in biology. An ability to control the oxygen sensing mechanism in cells, potentially using small molecules that do not disrupt oxygen consumption, would open valuable therapeutic avenues that could have a profound impact on a diverse range of diseases.
Regulation of the desensitization and ion selectivity of ATP‐gated P2X2channels by phosphoinositides
Authors: Fujiwara Yuichiro , Kubo Yoshihiro
Published: July 2006

Phosphoinositides (PIPns) are known to regulate the activity of some ion channels. Here we determined that ATP‐gated P2X2channels also are regulated by PIPns, and investigated the structural background and the unique features of this regulation. We initially used two‐electrode voltage clamp to analyse the electrophysiological properties of P2X2channels expressed inXenopusoocytes, and observed that preincubation with wortmannin or LY294002, two PI3K inhibitors, accelerated channel desensitization. K365Q or K369Q mutation of the conserved, positively charged, amino acid residues in the proximal region of the cytoplasmic C‐terminal domain also accelerated desensitization, whereas a K365R or K369R mutation did not. We observed that the permeability of the channel toN‐methyl‐d‐glucamine (NMDG) transiently increased and then decreased after ATP application, and that the speed of the decrease was accelerated by K365Q or K369Q mutation or PI3K inhibition. Using GST‐tagged recombinant proteins spanning the proximal C‐terminal region, we then analysed their binding of the P2X2cytoplasmic domain to anionic lipids using PIPns‐coated nitrocellulose membranes. We found that the recombinant proteins that included the positively charged region bound to PIPs and PIP2s, and that this binding was eliminated by the K365Q and K369Q mutations. We also used a fluorescence assay to confirm that fusion proteins comprising the proximal C‐terminal region of P2X2with EGFP expressed in COS‐7 cells closely associated with the membrane. Taken together, these results show that membrane‐bound PIPns play a key role in maintaining channel activity and regulating pore dilation through electrostatic interaction with the proximal region of the P2X2cytoplasmic C‐terminal domain.
Brassinosteroids Regulate Dissociation of BKI1, a Negative Regulator of BRI1 Signaling, from the Plasma Membrane
Authors: Wang Xuelu , Chory Joanne
Published: July 2006

Brassinosteroids, the steroid hormones of plants, are perceived at the plasma membrane by a leucine-rich repeat receptor serine/threonine kinase called BRI1. We report a BRI1-interacting protein, BKI1, which is a negative regulator of brassinosteroid signaling. Brassinosteroids cause the rapid dissociation of BKI1–yellow fluorescent protein from the plasma membrane in a process that is dependent on BRI1-kinase. BKI1 is a substrate of BRI1 kinase and limits the interaction of BRI1 with its proposed coreceptor, BAK1, suggesting that BKI1 prevents the activation of BRI1.
Hexagonal Mesoporous Germanium
Authors: Armatas Gerasimos S. , Kanatzidis Mercouri G.
Published: July 2006

The blending of mesoporosity with the properties of semiconductors promises new types of multifunctional nanomaterials. It would be particularly interesting to combine the shape selectivity of a mesoporous oxide with the electronic and photonic characteristics of a useful semiconductor. We demonstrated the synthesis of a mesoporous germanium semiconductor using liquid-crystals-templated chemistry. The template removal was achieved by a two-step ion-exchange thermal procedure. This semiconductive mesoporous form of germanium possesses hexagonal pore ordering with very high surface area and exhibits strongly size-dependent optical properties as well as photoluminescence.
Prevention and Self-Treatment of Traveler's Diarrhea
Authors: Diemert David J.
Published: July 2006

Of the millions who travel from the industrialized world to developing countries every year, between 20% and 50% will develop at least one episode of diarrhea, making it the most common medical ailment afflicting travelers. Although usually a mild illness, traveler's diarrhea can result in significant morbidity and hardship overseas. Precautions can be taken to minimize the risk of developing traveler's diarrhea, either through avoidance of potentially contaminated food or drink or through various prophylactic measures, including both nonpharmacological and antimicrobial strategies. If diarrhea does develop despite the precautions taken, effective treatment—usually a combination of an antibiotic and an antimotility agent—can be brought by the traveler and initiated as soon as symptoms develop. In the future, vaccines—several of which are in the advanced stages of clinical testing—may be added to the list of prophylactic measures.
Peptide Antimicrobial Agents
Authors: Jenssen Håvard , Hamill Pamela , Hancock Robert E. W.
Published: July 2006

Antimicrobial host defense peptides are produced by all complex organisms as well as some microbes and have diverse and complex antimicrobial activities. Collectively these peptides demonstrate a broad range of antiviral and antibacterial activities and modes of action, and it is important to distinguish between direct microbicidal and indirect activities against such pathogens. The structural requirements of peptides for antiviral and antibacterial activities are evaluated in light of the diverse set of primary and secondary structures described for host defense peptides. Peptides with antifungal and antiparasitic activities are discussed in less detail, although the broad-spectrum activities of such peptides indicate that they are important host defense molecules. Knowledge regarding the relationship between peptide structure and function as well as their mechanism of action is being applied in the design of antimicrobial peptide variants as potential novel therapeutic agents.
Insights into the Interaction between Influenza Virus and Pneumococcus
Authors: McCullers Jonathan A.
Published: July 2006

Bacterial infections following influenza are an important cause of morbidity and mortality worldwide. Based on the historical importance of pneumonia as a cause of death during pandemic influenza, the increasingly likely possibility that highly pathogenic avian influenza viruses will trigger the next worldwide pandemic underscores the need to understand the multiple mechanisms underlying the interaction between influenza virus and bacterial pathogens such asStreptococcus pneumoniae. There is ample evidence to support the historical view that influenza virus alters the lungs in a way that predisposes to adherence, invasion, and induction of disease by pneumococcus. Access to receptors is a key factor and may be facilitated by the virus through epithelial damage, by exposure or up-regulation of receptors, or by provoking the epithelial regeneration response to cytotoxic damage. More recent data indicate that alteration of the immune response by diminishing the ability of the host to clear pneumococcus or by amplification of the inflammatory cascade is another key factor. Identification and exploration of the underlying mechanisms responsible for this synergism will provide targets for prevention and treatment using drugs and vaccines.
Regular exercise did not modify significantly superoxide dismutase activity in adolescents with Down’s syndrome
Authors: Ordoñez F J , Rosety M , Rosety-Rodriguez M
Published: July 2006

Background:Superoxide dismutase (SOD) overexpression in people with Down’s syndrome negatively modifies the equilibrium SOD/glutathione peroxidase+catalase, which may ultimately lead to an increased hydroxyl radical formation.

Objective:To assess the influence of regular exercise on erythrocyte SOD activity to determine the ability of exercise to attenuate increased oxidative damage.

Method:Thirty one male adolescents with Down’s syndrome (mean (SD) age 16.3 (1.1) years) performed a 12 week training programme (three days a week), consisting of a warm up, exercise at a work intensity of 60–75% of peak heart rate (the latter calculated from 194.5 – (0.56 × age)), and a cool down period. The reduction of cytochromecat 550 nm was used to monitor SOD activity in the supernatant of erythrocyte haemolysates.

Results:Mean (SD) SOD activity in non-exercised adolescents with Down’s syndrome was 679.0 (82) U/g haemoglobin (95% confidence interval 642.2 to 715.8). After the 12 week training programme, it had increased to 706.8 (91) U/g haemoglobin (95% confidence interval 663.9 to 749.8). This increase was not significant (p  =  0.099).

Conclusion:Regular exercise did not significantly increase SOD activity and consequently did not affect the unbalanced equilibrium SOD/glutathione peroxidase+catalase observed in patients with Down’s syndrome. Further studies are required to assess the behaviour of other antioxidant enzymes included in this pathway in order to highlight potential benefits of regular exercise in redox metabolism of patients with Down’s syndrome.
Root hair cell walls: filling in the frameworkThis review is one of a selection of papers published in the Special Issue on Plant Cell Biology.
Authors: Galway M.E.
Published: July 2006

Rapid progress is being made in determining the composition, synthesis, and mechanical properties of plant cell walls. Although tip-growing root hairs provide an excellent example of high-speed cell wall assembly, they have been relatively neglected by researchers interested in cell walls and those interested in tip growth. This review aims to present the root hair as an experimental system for future cell wall studies by assembling recent discoveries about the walls onto the existing framework based on older information. Most recent data come from arabidopsis ( Arabidopsis thaliana (L.) Heynh) and model legumes. Evidence supporting the turgor-mediated expansion of hair cell walls is considered, along with a survey of three components needed for cell wall expansion without rupture: cellulose (the role of CesA cellulose synthases is also addressed), Csld3, a cellulose synthase-like protein, and Lrx1, a cell wall protein. Further clues about hair cell wall composition have been obtained from gene expression studies and the use of monoclonal antibodies. Finally, there is a review of the experimental evidence that (i) hairs near the hypocotyl differ developmentally and structurally from other hairs and (ii) biosynthesis of wall components in hairs may differ significantly from the epidermal cells that they grew from. All of these recent advances suggest that root hairs could provide valuable data to augment models of plant cell walls based on more conventional cell types.
Trichome cell morphogenesis inArabidopsis: a continuum of cellular decisionsThis review is one of a selection of papers published in the Special Issue on Plant Cell Biology.
Authors: Mathur Jaideep
Published: July 2006

In keeping with the myriad functions carried out by plants, their component cells display an amazing diversity of shapes and sizes. How is a precise cell form achieved? In recent years, the single-celled, branched, aerial epidermal trichome of Arabidopsis thaliana L. (Heynh) has emerged as a model cell for understanding the cell biological and molecular basis underlying the development of cell shape in plants. Here, I critique the recent information gleaned from dissecting trichome cell morphogenesis in Arabidopsis and identify areas and questions that can be further addressed using this unique cell type.
The emerging importance of cyclin-dependent kinase inhibitors in the regulation of the plant cell cycle and related processesThis review is one of a selection of papers published in the Special Issue on Plant Cell Biology.
Authors: Wang Hong , Zhou Yongming , Fowke Larry C.
Published: July 2006

The cell division cycle in plants as in other eukaryotes is controlled by the cyclin-dependent kinase (CDK). This CDK paradigm determines that developmental cues and environmental signals need to impinge on the CDK complex to affect the cell cycle. An important part of understanding cell cycle regulation is to understand how CDK is regulated by various factors. In addition, there are features that set the cell cycle regulation in plants apart from that in other eukaryotes such as animals. Our knowledge of the molecular mechanisms that underlie the differences is poor. A family of plant CDK inhibitor proteins has been identified. The plant CDK inhibitors share similarity with a family of animal CDK inhibitors in a small region, while most of the sequence and the structural layout of the plant CDK inhibitors are different from the animal counterparts. Studies of plant CDK inhibitors have been performed mostly with the CDK inhibitors from Arabidopsis called ICKs (also referred to as KRPs). ICKs interact with D-type cyclins and A-type CDK. Overexpression of ICKs has been shown to affect cell division, plant growth, and morphogenesis. Studies of ICKs have also provided insightful information on the control of endoreduplication in plants. These aspects as well as cellular localization and protein regulation of ICKs are reviewed.
A second enantiornithean (Aves: Ornithothoraces) wing from the Early Cretaceous Xiagou Formation near Changma, Gansu Province, People's Republic of China
Authors: Harris Jerald D , Lamanna Matthew C , You Hai-lu , Ji Shu-an , Ji Qiang
Published: July 2006

A new specimen of an enantiornithean bird from the Lower Cretaceous Xiagou Formation of Gansu Province, northwestern China, consists of an articulated distal left humerus, ulna, radius, carpus, and manus. The specimen may represent a primitive enantiornithean because it lacks a longitudinal sulcus on the radius, has incompletely fused alular and major metacarpals, and possibly retains a remnant of a second phalanx on the minor digit. It differs from all other known enantiornitheans, and exhibits possible autapomorphies, including peculiar, flat humeral epicondyles, a pair of eminences on the distal minor metacarpal, and an enormous flexor tuberculum on the alular ungual. The specimen probably pertains to the same taxon as a previously described enantiornithean arm from Changma; the incompleteness of the taxon precludes erecting a new name, but it provides new information concerning enantiornithean diversity in the Early Cretaceous of central Asia.
Diagenetic fluorapatite and aluminum phosphatesulphate in the Paleoproterozoic Thelon Formation and Hornby Bay Group, northwestern Canadian Shield
Authors: Gall Q , Donaldson J A
Published: July 2006

In the northwestern part of the Canadian Shield, fluorapatite and a rare-earth element-bearing hydrated aluminum phosphatesulphate mineral (APS) occur as cements in continental successions near the base of the Paleoproterozoic Thelon Formation (Thelon Basin) and Hornby Bay Group (Hornby Bay Basin). These minerals occupy interstitial sites, form euhedral crystals, display micro-scale zonation, make up part of an unmetamorphosed paragenetic assemblage, and are distributed in correlative units across thousands of square kilometres, suggesting a diagenetic origin. Stratigraphy, geochronology, and other lines of evidence suggest that the Thelon Formation and Hornby Bay Group containing these phosphatic cements, as well as the Ellice Formation and Athabasca Group, are correlative and may have been originally interconnected. The evidence suggests that the basal Thelon Formation and the Hornby Bay Group underwent similar, and approximately coeval, diagenetic mineral paragenesis. Furthermore, the diagenetic fluids in these different locations must have been remarkably similar, especially those that produced the delicate APS mineral. Compared to phosphatic cements in the Hornby Bay and Thelon basins, unmineralized sandstone in the Athabasca Basin contains "crandallite group" and fluorapatite cements higher in the basin fill sequence (Wolverine Point Formation) in tuffaceous sandstone and as relatively early cement in the paragenetic sequence.
Physiology of individual late-run Fraser River sockeye salmon (Oncorhynchus nerka) sampled in the ocean correlates with fate during spawning migration
Authors: Cooke Steven J , Hinch Scott G , Crossin Glenn T , Patterson David A , English Karl K , Shrimpton J Mark , Kraak Glen Van Der , Farrell Anthony P
Published: July 2006

Beginning in 1995, segments of the late-run sockeye salmon (Oncorhynchus nerka) stocks from the Fraser River, British Columbia, have initiated upriver spawning migration up to 6 weeks earlier than historical records; and those fish have experienced high rates of en route mortality. We examined the correlations between physiological and energetic status prior to river entry with subsequent migratory performance of individual salmon using telemetry and noninvasive biopsies for AdamsThompsonShuswap (Adams) and WeaverHarrison (WH) stocks. Salmon that failed to reach the river were characterized by a tendency to have elevated levels of chronic and acute stress indicators. For one stock of fish (i.e., Adams) that entered the river, those that died before reaching spawning grounds were individuals with low gross somatic energy. Furthermore, females tended to have elevated plasma estradiol levels. When contrasting fish with different behaviours and fates, fish that did not hold in the estuary and subsequently died tended to have less energy than fish that held and reached spawning areas. Females from the former group also had higher 11-ketotestosterone and estradiol levels relative to those from the later group. These data suggest that differences in physiological and energetic status may be associated with high en route mortality in late-run sockeye salmon.
Interactions of slimy sculpin (Cottus cognatus) with native and nonnative trout: consequences for growth
Authors: Zimmerman Julie KH , Vondracek Bruce
Published: July 2006

We examined growth of native slimy sculpin (Cottus cognatus), native brook trout (Salvelinus fontinalis), and nonnative brown trout (Salmo trutta) to investigate potential interactions of a native nongame fish with native and nonnative trout. Enclosures (1 m2) were stocked with five treatments (juvenile brown trout with sculpin, juvenile brook trout with sculpin, and single species controls) at three densities. Treatments (with replication) were placed in riffles in Valley Creek, Minnesota, and growth rates were measured for six experiments. We examined the difference in growth of each species in combined species treatments compared with each species alone. We did not find evidence of inter actions between brook trout and sculpin, regardless of density or fish size. However, sculpin gained greater mass when alone than with brown trout when sculpin were >16 g. Likewise, brown trout grew more when alone than with sculpin when brown trout were >24 g. In contrast, brown trout ≤5 g grew more with sculpin compared with treatments alone. We suggest that native brook trout and sculpin coexist without evidence of competition, whereas nonnative brown trout may compete with sculpin.