bluuebunny/crossref_metadata_2025 huggingface dataset:
A low-dimensional deformation model for cancer cells in flow
Authors: Lee A. M. , Berny-Lang M. A. , Liao S. , Kanso E. , Kuhn P. , McCarty O. J. T. , Newton P. K.
Published: August 2012

A low-dimensional parametric deformation model of a cancer cell under shear flow is developed. The model is built around an experiment in which MDA-MB-231 adherent cells are subjected to flow with increasing shear. The cell surface deformation is imaged using differential interference contrast microscopy imaging techniques until the cell releases into the flow. We post-process the time sequence of images using an active shape model from which we obtain the principal components of deformation. These principal components are then used to obtain the parameters in an empirical constitutive equation determining the cell deformations as a function of the fluid normal and shear forces imparted. The cell surface is modeled as a 2D Gaussian interface which can be deformed with three active parameters: H (height), σx (x-width), and σy (y-width). Fluid forces are calculated on the cell surface by discretizing the surface with regularized Stokeslets, and the flow is driven by a stochastically fluctuating pressure gradient. The Stokeslet strengths are obtained so that viscous boundary conditions are enforced on the surface of the cell and the surrounding plate. We show that the low-dimensional model is able to capture the principal deformations of the cell reasonably well and argue that active shape models can be exploited further as a useful tool to bridge the gap between experiments, models, and numerical simulations in this biological setting.
Governing Climate Change Transnationally: Assessing the Evidence from a Database of Sixty Initiatives
Authors: Bulkeley Harriet , Andonova Liliana , Bäckstrand Karin , Betsill Michele , Compagnon Daniel , Duffy Rosaleen , Kolk Ans , Hoffmann Matthew , Levy David , Newell Peter , Milledge Tori , Paterson Matthew , Pattberg Philipp , VanDeveer Stacy
Published: August 2012

With this paper we present an analysis of sixty transnational governance initiatives and assess the implications for our understanding of the roles of public and private actors, the legitimacy of governance ‘beyond’ the state, and the North–South dimensions of governing climate change. In the first part of the paper we examine the notion of transnational governance and its applicability in the climate change arena, reflecting on the history and emergence of transnational governance initiatives in this issue area and key areas of debate. In the second part of the paper we present the findings from the database and its analysis. Focusing on three core issues, the roles of public and private actors in governing transnationally, the functions that such initiatives perform, and the ways in which accountability for governing global environmental issues might be achieved, we suggest that significant distinctions are emerging in the universe of transnational climate governance which may have considerable implications for the governing of global environmental issues. In conclusion, we reflect on these findings and the subsequent consequences for the governance of climate change.
Synthesis, Acetylcholinesterase and Alkaline Phosphatase Inhibition of Some New 1,2,4-Triazole and 1,3,4-Thiadiazole Derivatives
Authors: Khan Imtiaz , Hanif Muhammad , Hussain Muhammad Tahir , Khan Aftab Ahmed , Aslam Muhammad Adil S. , Rama Nasim Hasan , Iqbal Jamshed
Published: August 2012

A new series of 4,5-disubstituted-2,4-dihydro-3H-1,2,4-triazole-3-thiones (6a–s) and 2,5-disubstituted-1,3,4-thiadiazoles (7a–h) was synthesized by intramolecular dehydrocyclization of various 1,4-disubstituted thiosemicarbazide derivatives (5a–s) by refluxing in 4 N aqueous sodium hydroxide and by overnight stirring with polyphosphoric acid, respectively. The structures of these compounds were characterized by IR, 1H and 13C NMR, elemental analysis and mass spectroscopic studies. All the synthesized compounds were screened for their acetylcholinesterase and alkaline phosphatase inhibition studies. Most of the tested compounds showed promising activities, amongst them (6k) and (6q) showed excellent acetylcholinesterase inhibitory activity with IC50 0.241 ± 0.012 and 0.260 ± 0.013 µM, respectively, as compared with those of standard drug whereas the compound (6p), with IC50 0.044 ± 0.001 µM, was found to be the most potent inhibitor of alkaline phosphatase.
Geographically distinct Ceratophyllum demersum populations differ in growth, photosynthetic responses and phenotypic plasticity to nitrogen availability
Authors: Hyldgaard Benita , Sorrell Brian , Olesen Birgit , Riis Tenna , Brix Hans
Published: August 2012

Two geographically distinct populations of the submerged aquatic macrophyte Ceratophyllum demersum L. were compared after acclimation to five different nitrogen concentrations (0.005, 0.02, 0.05, 0.1 and 0.2 mM N) in a common garden setup. The two populations were an apparent invasive population from New Zealand (NZ) and a noninvasive population from Denmark (DK). The populations were compared with a focus on both morphological and physiological traits. The NZ population had higher relative growth rates (RGRs) and photosynthesis rates (Pmax) (range: RGR, 0.06–0.08 per day; Pmax, 200–395 µmol O2 g–1 dry mass (DM) h–1) compared with the Danish population (range: RGR, 0.02–0.05 per day; Pmax, 88–169 µmol O2 g–1 DM h–1). The larger, faster-growing NZ population also showed higher plasticity than the DK population in response to nitrogen in traits important for growth. Hence, the observed differences in growth behaviour between the two populations are a result of genetic differences and differences in their level of plasticity. Here, we show that two populations of the same species from similar climates but different geographical areas can differ in several ecophysiological traits after growth in a common garden setup.
Two sympatric root hemiparasitic Pedicularis species differ in host dependency and selectivity under phosphorus limitation
Authors: Li Ai-Rong , Smith F. Andrew , Smith Sally E. , Guan Kai-Yun
Published: August 2012

Parasitic biology of Pedicularis L. (Orobanchaceae) has been underinvestigated despite its wide distribution and potential ecological significance. To better understand the parasitic aspects of the root hemiparasites, host–parasite interactions were investigated with two sympatric Pedicularis species, Pedicularis rex C. B. Clarke and Pedicularis tricolor Hand.-Mazz., at two developmental stages. Plant DW, shoot phosphorus (P) content, root : shoot ratio and number of haustoria were measured in Pedicularis grown with either a host plant or a plant of its own species in pot experiments. In addition, effects of parasitism and intraspecific competition on growth and biomass allocation in four host species belonging to three major functional groups (grasses, legumes and forbs) were investigated. The two Pedicularis species showed obvious host preference, but preferred different host species. Interactions between Pedicularis and their hosts depended on both species identity and developmental stages of the partners. Overall, P. rex showed much weaker host dependency and less damage to hosts than P. tricolor. Interspecific variations were observed among different host species in their responses to intraspecific competition and parasitism. We concluded that different Pedicularis-host pairs showed different interaction patterns. Sympatric Pedicularis may have differential influence on plant community structure and productivity.
Targeting angiogenesis in the pathological ovary
Authors: Duncan W. Colin , Nio-Kobayashi Junko
Published: August 2012

The ovary is a key tissue in the study of physiological neo-vascularisation in the adult and its study has highlighted important molecules involved in the regulation of angiogenesis in vivo. These include vascular endothelial growth factor, delta-like ligand 4, thrombospondin-1, prokineticin-1 and prostaglandin E2. Targeting these molecular pathways has therapeutic potential and their manipulation has an increasing preclinical and clinical role in the management of the pathological ovary. Targeting angiogenic pathways has utility in the promotion of ovarian angiogenesis to improve tissue and follicle survival and function as well as the prevention and management of ovarian hyperstimulation syndrome. There is a theoretical possibility that targeting angiogenesis may improve the function of the polycystic ovary and a real role for targeting angiogenesis in ovarian cancer.
Resolving conflict in eutherian mammal phylogeny using phylogenomics and the multispecies coalescent model
Authors: Song Sen , Liu Liang , Edwards Scott V. , Wu Shaoyuan
Published: August 2012

The reconstruction of the Tree of Life has relied almost entirely on concatenation methods, which do not accommodate gene tree heterogeneity, a property that simulations and theory have identified as a likely cause of incongruent phylogenies. However, this incongruence has not yet been demonstrated in empirical studies. Several key relationships among eutherian mammals remain controversial and conflicting among previous studies, including the root of eutherian tree and the relationships within Euarchontoglires and Laurasiatheria. Both Bayesian and maximum-likelihood analysis of genome-wide data of 447 nuclear genes from 37 species show that concatenation methods indeed yield strong incongruence in the phylogeny of eutherian mammals, as revealed by subsampling analyses of loci and taxa, which produced strongly conflicting topologies. In contrast, the coalescent methods, which accommodate gene tree heterogeneity, yield a phylogeny that is robust to variable gene and taxon sampling and is congruent with geographic data. The data also demonstrate that incomplete lineage sorting, a major source of gene tree heterogeneity, is relevant to deep-level phylogenies, such as those among eutherian mammals. Our results firmly place the eutherian root between Atlantogenata and Boreoeutheria and support ungulate polyphyly and a sister-group relationship between Scandentia and Primates. This study demonstrates that the incongruence introduced by concatenation methods is a major cause of long-standing uncertainty in the phylogeny of eutherian mammals, and the same may apply to other clades. Our analyses suggest that such incongruence can be resolved using phylogenomic data and coalescent methods that deal explicitly with gene tree heterogeneity.
Causes, consequences, and remedies for growth-induced solid stress in murine and human tumors
Authors: Stylianopoulos Triantafyllos , Martin John D. , Chauhan Vikash P. , Jain Saloni R. , Diop-Frimpong Benjamin , Bardeesy Nabeel , Smith Barbara L. , Ferrone Cristina R. , Hornicek Francis J. , Boucher Yves , Munn Lance L. , Jain Rakesh K.
Published: August 2012

The presence of growth-induced solid stresses in tumors has been suspected for some time, but these stresses were largely estimated using mathematical models. Solid stresses can deform the surrounding tissues and compress intratumoral lymphatic and blood vessels. Compression of lymphatic vessels elevates interstitial fluid pressure, whereas compression of blood vessels reduces blood flow. Reduced blood flow, in turn, leads to hypoxia, which promotes tumor progression, immunosuppression, inflammation, invasion, and metastasis and lowers the efficacy of chemo-, radio-, and immunotherapies. Thus, strategies designed to alleviate solid stress have the potential to improve cancer treatment. However, a lack of methods for measuring solid stress has hindered the development of solid stress-alleviating drugs. Here, we present a simple technique to estimate the growth-induced solid stress accumulated within animal and human tumors, and we show that this stress can be reduced by depleting cancer cells, fibroblasts, collagen, and/or hyaluronan, resulting in improved tumor perfusion. Furthermore, we show that therapeutic depletion of carcinoma-associated fibroblasts with an inhibitor of the sonic hedgehog pathway reduces solid stress, decompresses blood and lymphatic vessels, and increases perfusion. In addition to providing insights into the mechanopathology of tumors, our approach can serve as a rapid screen for stress-reducing and perfusion-enhancing drugs.
Identity-based inhibitory processing during focused attention
Authors: Machado Liana , Guiney Hayley , Struthers Philippa
Published: August 2012

Recent data suggest that the operating principles governing inhibition of distractor-related activity may deviate from dominant models describing inhibitory processing during selective attention. Here we aimed to gain a better understanding of these data in order to determine whether they actually defy premises of current models. In addition to providing evidence against noninhibitory accounts of the data (see especially Experiment 6), the results support three main novel findings that challenge current theories. First, the data provide evidence that inhibition overpowered excitation from ongoing external input (Experiments 1–4), which suggests that inhibitory control processes are more powerful than current models indicate. Second, negative effects emerged even when targets appeared alone (Experiment 5), which suggests that selection does not play an essential role in triggering inhibitory processing. Third, relatively early distractor-related activity was affected, which supports a role for inhibition prior to action control (Experiment 3). These findings suggest a need to revise current models describing inhibition of distracting information during selective attention.
The role of visual spatial attention in adult developmental dyslexia
Authors: Collis Nathan L. , Kohnen Saskia , Kinoshita Sachiko
Published: August 2012

The present study investigated the nature of visual spatial attention deficits in adults with developmental dyslexia, using a partial report task with five-letter, digit, and symbol strings. Participants responded by a manual key press to one of nine alternatives, which included other characters in the string, allowing an assessment of position errors as well as intrusion errors. The results showed that the dyslexic adults performed significantly worse than age-matched controls with letter and digit strings but not with symbol strings. Both groups produced W-shaped serial position functions with letter and digit strings. The dyslexics' deficits with letter string stimuli were limited to position errors, specifically at the string-interior positions 2 and 4. These errors correlated with letter transposition reading errors (e.g., reading slat as “salt”), but not with the Rapid Automatized Naming (RAN) task. Overall, these results suggest that the dyslexic adults have a visual spatial attention deficit; however, the deficit does not reflect a reduced span in visual–spatial attention, but a deficit in processing a string of letters in parallel, probably due to difficulty in the coding of letter position.
Molecular Dynamics simulation of electrical field induced conformational transition and associated frictional performance of monomolecular films
Authors: Ma X , Shrotriya Pranav
Published: August 2012

Sparse monomolecular film assemblies with polar end groups such as carboxyl have attracted considerable interest because of their ability to undergo conformational transition under electrical fields. We report the results from molecular dynamics simulation of electrical field induced conformational transitions and associated frictional performance of carboxyl-terminated monomolecular films. Simulation results indicate that the density of the monomolecular film has a significant influence on the conformational transition under electrical fields. In the case of loose-packed monomolecular films, carboxyl-terminated chains cluster together to form a disordered film due to large interchain separation. Under the application of a positive electrical field, the chain backbone rotates and lies down on the substrate forming disordered clusters, whereas under the application of negative electrical fields, the chains stand up and cluster together to form disordered clusters. Under shallow indentation with a purely repulsive indenter, loose-packed monomolecular films subjected to a positive electrical field exhibit a lower level of frictional response compared with films subjected to negative and no electrical fields. In the case of close-packed monomolecular films, the molecular chains assemble in an ordered film and the space is not enough for backbone chains to generate large-scale conformational transition. Due to this spatial limitation, the applied electrical field was not found to have any influence on the backbone chain rotation and associated frictional response under shallow indentations with a purely repulsive indenter.
Evaluating how we evaluate
Authors: Vale Ronald D.
Published: August 2012

Evaluation of scientific work underlies the process of career advancement in academic science, with publications being a fundamental metric. Many aspects of the evaluation process for grants and promotions are deeply ingrained in institutions and funding agencies and have been altered very little in the past several decades, despite substantial changes that have taken place in the scientific work force, the funding landscape, and the way that science is being conducted. This article examines how scientific productivity is being evaluated, what it is rewarding, where it falls short, and why richer information than a standard curriculum vitae/biosketch might provide a more accurate picture of scientific and educational contributions. The article also explores how the evaluation process exerts a profound influence on many aspects of the scientific enterprise, including the training of new scientists, the way in which grant resources are distributed, the manner in which new knowledge is published, and the culture of science itself.
Development and Application of a Methodology to Determine Free Ferulic Acid and Ferulic Acid Ester‐Linked to Different Types of Carbohydrates in Cereal Products
Authors: Vaidyanathan Sharmila , Bunzel Mirko
Published: August 2012

Ferulic acid bioavailability is dependent on its form present in food. This necessitates a methodology to quantify different groups of ferulic acid derivatives in food products, especially cereal‐based products. The aim of the proposed methodology is to separate and quantify ferulic acid ester‐linked to mono‐ and/or oligosaccharides (OF), to soluble polysaccharides (SPF), and to insoluble polysaccharides (IPF) as well as in its free form. Development and partial validation of this method, which was widely based on liquid/liquid extraction and precipitation steps, was performed using characterized standard materials isolated from corn bran. As the determination of OF was one of the major goals of this methodology, three different feruloylated mono‐ and oligosaccharides were used for method development and validation. To determine the accuracy of the method, ferulic acid–containing standard materials added to a starch matrix were extracted and separated according to the developed protocol. The separated ferulic acid esters were saponified before ferulic acid was analyzed by reversed phase HPLC. Recovery rates were generally between 70 and 103%, with the lowest recovery rates for SPF and highest recovery rates for IPF and OF. Finally, the applicability of the method to unprocessed and processed wheat bran samples was demonstrated.
Cooking, Roasting, and Fermentation of Chickpeas, Lentils, Peas, and Soybeans for Fortification of Leavened Bread
Authors: Baik Byung‐Kee , Han In Hwa
Published: August 2012

The effects of cooking, roasting, and fermentation on the composition and protein properties of grain legumes and the characteristics of dough and bread incorporated with legume flours were determined to identify an appropriate pretreatment. Oligosaccharide content of legumes was reduced by 76.2–96.9% by fermentation, 44.0–64.0% by roasting, and 28.4–70.1% by cooking. Cooking and roasting decreased protein solubility but improved in vitro protein digestibility. Mixograph absorption of wheat and legume flour blends increased from 50–52% for raw legumes to 68–76, 62–64, and 74–80% for cooked, roasted, and fermented ones, respectively. Bread dough with cooked or roasted legume flour was less sticky than that with raw or fermented legume flour. Loaf volume of bread baked from wheat and raw or roasted legume flour blends with or without gluten addition was consistently highest for chickpeas, less for peas and lentils, and lowest for soybeans. Roasted legume flour exhibited more appealing aroma and greater loaf volume of bread than cooked legume flour, and it appears to be the most appropriate preprocessing method for incorporation into bread.
Identification, Characterization, and Distribution of Acidovorax avenae subsp. avenae Associated with Creeping Bentgrass Etiolation and Decline
Authors: Giordano Paul R. , Chaves Arielle M. , Mitkowski Nathaniel A. , Vargas Joseph M.
Published: August 2012

Bacterial etiolation and decline caused by Acidovorax avenae subsp. avenae is an emerging disease of creeping bentgrass (Agrostis stolonifera) in and around the transition zone, a unique area of turfgrass culture between cool and warm regions of the United States. It is suspected that the disease has been present for many years, although diagnosis of the first occurrence was not reported until 2010. Solicitation of samples from golf courses in 2010 and 2011 was undertaken to investigate the prevalence and dissemination of Acidovorax avenae subsp. avenae on creeping bentgrass. At least 21 isolates from 13 states associated with these outbreaks on golf courses were confirmed as A. avenae subsp. avenae by pathogenicity assays and 16S rDNA sequence analysis at two independent locations. Pathogenicity testing of bacterial isolates from creeping bentgrass samples exhibiting heavy bacterial streaming confirmed A. avenae subsp. avenae as the only bacterium to cause significant disease symptoms and turfgrass decline. Host range inoculations revealed isolates of A. avenae subsp. avenae to be pathogenic on all Agrostis stolonifera cultivars tested, with slight but significant differences in disease severity on particular cultivars. Other turfgrass hosts tested were only mildly susceptible to Acidovorax avenae subsp. avenae infection. This study initiated research on A. avenae subsp. avenae pathogenicity causing a previously uncharacterized disease of creeping bentgrass putting greens in the United States.
Comparison ofAlternariaspp. Collected in Italy from Apple withA. maliand Other AM-Toxin Producing Strains
Authors: Rotondo F. , Collina M. , Brunelli A. , Pryor B. M.
Published: August 2012

Since 1999, a disease of apple caused by an Alternaria sp. has been affecting orchards in northern Italy resulting in necrotic spots on leaves and on fruit. Forty-four single-spored isolates were obtained from diseased plant materials to investigate the diversity of this fungus in Italy and to compare these isolates to isolates of Alternaria associated with apple disease in previous studies, including A. mali, causal agent of apple blotch. All isolates, including the reference strains, were tested for pathogenicity utilizing in vitro bioassays on detached leaf or on fruit (‘Golden Delicious’). In addition, morphological characterizations were conducted describing both the three-dimensional sporulation pattern and the colony morphology of each isolate. In order to assess the genetic diversity within the Italian Alternaria population, sequence characterization of specific loci and anonymous regions (endoPG, OPA1-3, OPA2-1, and OPA10-2) and genetic fingerprinting based on amplified fragment length polymorphism and inter simple sequence repeat markers were performed. The single spore isolates exhibited differential pathogenicity, which did not correlate with the morphological groupings or to groupings defined by molecular approaches. Moreover, 10 pathogenic isolates out of the 44 single-spored tested were positive for the host-specific AM-toxin gene based upon polymerase chain reaction amplification using specific primers for the AM-toxin gene. This suggests that the production of the AM-toxin may be involved in pathogenesis by some of the Italian isolates of A. alternata from apple. However, this research also suggests that a number of different Alternaria genotypes and morphotypes may be responsible for the apple disease in Italy and that a single taxon cannot be defined as the sole causal agent.
Collective navigation of cargo-carrying swarms
Authors: Shklarsh Adi , Finkelshtein Alin , Ariel Gil , Kalisman Oren , Ingham Colin , Ben-Jacob Eshel
Published: August 2012

Much effort has been devoted to the study of swarming and collective navigation of micro-organisms, insects, fish, birds and other organisms, as well as multi-agent simulations and to the study of real robots. It is well known that insect swarms can carry cargo. The studies here are motivated by a less well-known phenomenon: cargo transport by bacteria swarms. We begin with a concise review of how bacteria swarms carry natural, micrometre-scale objects larger than the bacteria (e.g. fungal spores) as well as man-made beads and capsules (for drug delivery). A comparison of the trajectories of virtual beads in simulations (using different putative coupling between the virtual beads and the bacteria) with the observed trajectories of transported fungal spores implies the existence of adaptable coupling. Motivated by these observations, we devised new, multi-agent-based studies of cargo transport by agent swarms. As a first step, we extended previous modelling of collective navigation of simple bacteria-inspired agents in complex terrain, using three putative models of agent–cargo coupling. We found that cargo-carrying swarms can navigate efficiently in a complex landscape. We further investigated how the stability, elasticity and other features of agent–cargo bonds influence the collective motion and the transport of the cargo, and found sharp phase shifts and dual successful strategies for cargo delivery. Further understanding of such mechanisms may provide valuable clues to understand cargo-transport by smart swarms of other organisms as well as by man-made swarming robots.
A visco-poroelastic theory for polymeric gels
Authors: Wang Xiao , Hong Wei
Published: August 2012

A polymeric gel can imbibe solvent and swell. Besides the dilatational mode of deformation, which involves long-range solvent migration, a gel may also undergo volume-conserved deformation. For a macroscopic gel with covalent cross-links, the volume-conserved deformation is usually much faster. However, these two modes are coupled for deformation at the microscopic level and for gels containing physical cross-links or large solvent molecules. In this paper, we seek to formulate a unified theoretical framework for the transient behaviour of polymeric gels to account for both solvent migration and viscoelastic deformation. Under this framework, we further develop a simple material model, and implement it into a finite-element code for numerical calculations. By simultaneously tracking the solvent migration and motion of polymer network, we evolve the inhomogeneous fields of stress and chemical potential. Several initial-boundary-value problems are solved as illustrative examples. For macroscopic gels with low viscosity, the time scales for viscoelasticity and poroelasticity are separated, and the long-term behaviour is just as that predicted by a poroelastic model. For structures or processes involving sizes comparable to the intrinsic length of a material, the viscoelasticity and poroelasticity must be considered simultaneously, especially when studying impact responses.
Altitude acts as an environmental filter on phylogenetic composition, traits and diversity in bee communities
Authors: Hoiss Bernhard , Krauss Jochen , Potts Simon G. , Roberts Stuart , Steffan-Dewenter Ingolf
Published: August 2012

Knowledge about the phylogeny and ecology of communities along environmental gradients helps to disentangle the role of competition-driven processes and environmental filtering for community assembly. In this study, we evaluated patterns in species richness, phylogenetic structure and life-history traits of bee communities along altitudinal gradients in the Alps, Germany. We found a linear decline in species richness and abundance but increasing phylogenetic clustering in communities with increasing altitude. The proportion of social- and ground-nesting species, as well as mean body size and altitudinal range of bee communities, increased with increasing altitude, whereas the mean geographical distribution decreased. Our results suggest that community assembly at high altitudes is dominated by environmental filtering effects, whereas the relative importance of competition increases at low altitudes. We conclude that inherent phylogenetic and ecological species attributes at high altitudes pose a threat for less competitive alpine specialists with ongoing climate change.
Vacuolar CAX1 and CAX3 Influence Auxin Transport in Guard Cells via Regulation of Apoplastic pH
Authors: Cho Daeshik , Villiers Florent , Kroniewicz Laetitia , Lee Sangmee , Seo You Jin , Hirschi Kendal D. , Leonhardt Nathalie , Kwak June M.
Published: August 2012

CATION EXCHANGERs CAX1 and CAX3 are vacuolar ion transporters involved in ion homeostasis in plants. Widely expressed in the plant, they mediate calcium transport from the cytosol to the vacuole lumen using the proton gradient across the tonoplast. Here, we report an unexpected role of CAX1 and CAX3 in regulating apoplastic pH and describe how they contribute to auxin transport using the guard cell’s response as readout of hormone signaling and cross talk. We show that indole-3-acetic acid (IAA) inhibition of abscisic acid (ABA)-induced stomatal closure is impaired in cax1, cax3, and cax1/cax3. These mutants exhibited constitutive hypopolarization of the plasma membrane, and time-course analyses of membrane potential revealed that IAA-induced hyperpolarization of the plasma membrane is also altered in these mutants. Both ethylene and 1-naphthalene acetic acid inhibited ABA-triggered stomatal closure in cax1, cax3, and cax1/cax3, suggesting that auxin signaling cascades were functional and that a defect in IAA transport caused the phenotype of the cax mutants. Consistent with this finding, chemical inhibition of AUX1 in wild-type plants phenocopied the cax mutants. We also found that cax1/cax3 mutants have a higher apoplastic pH than the wild type, further supporting the hypothesis that there is a defect in IAA import in the cax mutants. Accordingly, we were able to fully restore IAA inhibition of ABA-induced stomatal closure in cax1, cax3, and cax1/cax3 when stomatal movement assays were carried out at a lower extracellular pH. Our results suggest a network linking the vacuolar cation exchangers to apoplastic pH maintenance that plays a crucial role in cellular processes.
The Grapevine Root-Specific Aquaporin VvPIP2;4N Controls Root Hydraulic Conductance and Leaf Gas Exchange under Well-Watered Conditions But Not under Water Stress
Authors: Perrone Irene , Gambino Giorgio , Chitarra Walter , Vitali Marco , Pagliarani Chiara , Riccomagno Nadia , Balestrini Raffaella , Kaldenhoff Ralf , Uehlein Norbert , Gribaudo Ivana , Schubert Andrea , Lovisolo Claudio
Published: August 2012

We functionally characterized the grape (Vitis vinifera) VvPIP2;4N (for Plasma membrane Intrinsic Protein) aquaporin gene. Expression of VvPIP2;4N in Xenopus laevis oocytes increased their swelling rate 54-fold. Northern blot and quantitative reverse transcription-polymerase chain reaction analyses showed that VvPIP2;4N is the most expressed PIP2 gene in root. In situ hybridization confirmed root localization in the cortical parenchyma and close to the endodermis. We then constitutively overexpressed VvPIP2;4N in grape ‘Brachetto’, and in the resulting transgenic plants we analyzed (1) the expression of endogenous and transgenic VvPIP2;4N and of four other aquaporins, (2) whole-plant, root, and leaf ecophysiological parameters, and (3) leaf abscisic acid content. Expression of transgenic VvPIP2;4N inhibited neither the expression of the endogenous gene nor that of other PIP aquaporins in both root and leaf. Under well-watered conditions, transgenic plants showed higher stomatal conductance, gas exchange, and shoot growth. The expression level of VvPIP2;4N (endogenous + transgene) was inversely correlated to root hydraulic resistance. The leaf component of total plant hydraulic resistance was low and unaffected by overexpression of VvPIP2;4N. Upon water stress, the overexpression of VvPIP2;4N induced a surge in leaf abscisic acid content and a decrease in stomatal conductance and leaf gas exchange. Our results show that aquaporin-mediated modifications of root hydraulics play a substantial role in the regulation of water flow in well-watered grapevine plants, while they have a minor role upon drought, probably because other signals, such as abscisic acid, take over the control of water flow.
A Set of Regioselective O-Methyltransferases Gives Rise to the Complex Pattern of Methoxylated Flavones in Sweet Basil
Authors: Berim Anna , Hyatt David C. , Gang David R.
Published: August 2012

Polymethoxylated flavonoids occur in a number of plant families, including the Lamiaceae. To date, the metabolic pathways giving rise to the diversity of these compounds have not been studied. Analysis of our expressed sequence tag database for four sweet basil (Ocimum basilicum) lines afforded identification of candidate flavonoid O-methyltransferase genes. Recombinant proteins displayed distinct substrate preferences and product specificities that can account for all detected 7-/6-/4′-methylated, 8-unsubstituted flavones. Their biochemical specialization revealed only certain metabolic routes to be highly favorable and therefore likely in vivo. Flavonoid O-methyltransferases catalyzing 4′- and 6-O-methylations shared high identity (approximately 90%), indicating that subtle sequence changes led to functional differentiation. Structure homology modeling suggested the involvement of several amino acid residues in defining the proteins’ stringent regioselectivities. The roles of these individual residues were confirmed by site-directed mutagenesis, revealing two discrete mechanisms as a basis for the switch between 6- and 4′-O-methylation of two different substrates. These findings delineate major pathways in a large segment of the flavone metabolic network and provide a foundation for its further elucidation.
Putative Glycosyltransferases and Other Plant Golgi Apparatus Proteins Are Revealed by LOPIT Proteomics
Authors: Nikolovski Nino , Rubtsov Denis , Segura Marcelo P. , Miles Godfrey P. , Stevens Tim J. , Dunkley Tom P.J. , Munro Sean , Lilley Kathryn S. , Dupree Paul
Published: August 2012

The Golgi apparatus is the central organelle in the secretory pathway and plays key roles in glycosylation, protein sorting, and secretion in plants. Enzymes involved in the biosynthesis of complex polysaccharides, glycoproteins, and glycolipids are located in this organelle, but the majority of them remain uncharacterized. Here, we studied the Arabidopsis (Arabidopsis thaliana) membrane proteome with a focus on the Golgi apparatus using localization of organelle proteins by isotope tagging. By applying multivariate data analysis to a combined data set of two new and two previously published localization of organelle proteins by isotope tagging experiments, we identified the subcellular localization of 1,110 proteins with high confidence. These include 197 Golgi apparatus proteins, 79 of which have not been localized previously by a high-confidence method, as well as the localization of 304 endoplasmic reticulum and 208 plasma membrane proteins. Comparison of the hydrophobic domains of the localized proteins showed that the single-span transmembrane domains have unique properties in each organelle. Many of the novel Golgi-localized proteins belong to uncharacterized protein families. Structure-based homology analysis identified 12 putative Golgi glycosyltransferase (GT) families that have no functionally characterized members and, therefore, are not yet assigned to a Carbohydrate-Active Enzymes database GT family. The substantial numbers of these putative GTs lead us to estimate that the true number of plant Golgi GTs might be one-third above those currently annotated. Other newly identified proteins are likely to be involved in the transport and interconversion of nucleotide sugar substrates as well as polysaccharide and protein modification.
Ageing and employers’ perceptions of labour costs and productivity
Authors: Conen Wieteke S. , van Dalen Hendrik P. , Henkens Kène
Published: August 2012

Purpose

The purpose of this paper is to examine employers’ perceptions of changes in the labour cost‐productivity gap due to the ageing of the workforce, the effects of tenure wages and employment protection on the perceived gap, and whether a perceived labour cost‐productivity gap affects employers’ recruitment and retention behaviour towards older workers.

Design/methodology/approach

The authors analyse surveys administered to employers in Denmark, France, Germany, Italy, the Netherlands, Poland and Sweden.

Findings

Approximately half of employers associate the ageing of the personnel with a growing gap between labour costs and productivity. Both the presence of tenure wages and employment protection rules increase the probability of employers perceiving a widening labour cost‐productivity gap due to the ageing of their workforce. A counterfactual shows that even when employment protection and tenure wage systems are abolished, 40 percent of employers expect a net cost increase. The expected labour cost‐productivity gap negatively affects both recruitment and retention of older workers.

Originality/value

In this paper, the wage‐productivity gap is examined through the perceptions of employers using an international comparative survey.
How do employed women perceive the reconciliation of work and family life?
Authors: Hennig Marina , Stuth Stefan , Ebach Mareike , Erika Hägglund Anna
Published: August 2012

Purpose

The purpose of this paper is to analyze how employed women perceive the reconciliation of work and family life in Denmark, Germany, France, Finland, Great Britain, Sweden and Switzerland. The paper seeks to explore why women in certain countries are more successful in combining family responsibilities with gainful employment.

Design/methodology/approach

Drawing on data from the International Social Survey Programme (ISSP) 2005, the questions are addressed by applying country specific linear regression analysis at the individual level, correlations at the country level as well as policy analysis.

Findings

The analysis shows that the most important factors influencing employed women's perception of the reconciliation are work load, the presence of children in the household and part‐time employment. In addition, the findings point at cross‐national differences. In countries where family policies focus on integrating men and women into the labour market, women rate the reconciliation of work and family life higher than in countries whose family policies aim at supporting the family.

Research limitations/implications

By comparing seven European countries the paper shows that family policies are closely related to employed women's perceptions of the reconciliation. In order to understand the interaction between the individual perception and the institutional framework, the paper suggests that further research is needed on women's perceptions in each country.

Originality/value

The paper explores how employed women perceive the reconciliation of work and family life in seven European countries and explains the differences by means of family policies.
Internationalization patterns of small and medium‐sized enterprises
Authors: Kuivalainen Olli , Sundqvist Sanna , Saarenketo Sami , McNaughton Rod
Published: August 2012

Purpose

The purpose of this paper is to present an overview of the conceptual frameworks and concepts with which the research on internationalization patterns of small and medium‐sized enterprises (SMEs) should be conducted.

Design/methodology/approach

A comprehensive overview of concepts and a conceptual framework to study internationalization patterns of SMEs is offered.

Findings

The complexities of existing definitions and methodologies for researching internationalization patterns are highlighted, and a synthesis of the issues is provided. An integrative model of internationalization pathways, and their antecedents and outcomes is presented.

Research limitations/implications

It is recommended that future research focuses especially on the time dimension of internationalization patterns. Future research can contribute to the literature by adopting a longitudinal approach with larger samples and more detailed cases to capture the dynamics of internationalization.

Practical implications

Practitioners might map their positions, and look for challenges and opportunities with regard to their chosen internationalization pattern. They can also benchmark other firms’ pathways and fine‐tune their own approach to internationalization.

Originality/value

The paper integrates a large body of research in an important research area in international marketing. It also provides guidance on how to conduct future research in the area, and introduces the content of this special issue of the International Marketing Review.
Prevalence and longitudinal trends of early internationalisation patterns among Canadian SMEs
Authors: Sui Sui , Yu Zhihao , Baum Matthias
Published: August 2012

Purpose

Recently, studies call for a more nuanced perspective on different internationalization patterns pursued by early internationalizers. These studies argue that most born global firms turn out to be born regional and that the proportion of true born global firms would be overestimated. Moreover, literature claims that the proportion of born global firms increases over time due to macroeconomic trends. The purpose of this paper is to investigate these assumptions by providing a dynamic perspective on the prevalence of different types of internationalization patterns among Canadian small and medium‐sized exporters (SMEs).

Design/methodology/approach

To empirically examine the ideas above, the authors constructed a unique large‐scale longitudinal (1997‐2004) dataset. A multinomial logit model is employed to estimate a firm's predicted probability, Ceteris paribus, of choosing different internationalization patterns: born global, born regional, and gradual internationalization.

Findings

It is found that born global firms indeed account for a smaller proportion than born regional firms (16 per cent vs 27 per cent). However, evidence is found that born globals and born regionals are increasingly established over time and that macroeconomic factors seem to account for this development, at least partially.

Originality/value

Combining a rigorous empirical analysis with a unique large‐scale longitudinal dataset, the paper addresses two fundamental research questions in the international entrepreneurship (IE) literature: which internationalization pattern prevails; and if the born global pattern is increasingly established over time. The paper therewith theoretically contributes by comparing the predictive value of different internationalization frameworks (international new venture (INV) framework, stage‐models and regionalization hypothesis), toward which there is considerable current debate.
Educational middle change leadership in New Zealand: the meat in the sandwich
Authors: Gregory Marshall Steven
Published: August 2012

Purpose

The purpose of this paper is to report findings from a larger study into the role of middle leaders of change in New Zealand higher education.

Design/methodology/approach

In total, ten middle leaders from the New Zealand higher education sector took part in a recent research project which examined successful change leadership in higher education. As part of that larger study, each middle leader answered questions about their views on being in the “middle” in their change leadership roles and their views on middle leadership in general.

Findings

The ten middle leaders all described their place in their respective organisations in terms of being “caught in between”, or “sandwiched between” senior management to whom they were accountable, lecturers whom they described as colleagues or peers, and subordinates for whom they had some functional and often moral responsibility. The paper discusses the perceptions of being in the “middle” and how change leaders reconcile their position as a subordinate, an equal and a superior. Insight is gained into how educational leaders reconcile their position in the “middle” as they hold management responsibility for both academic and general staff who are hierarchically, beneath them; lead teams of colleagues in collegial decision making; and answer to higher authority in the form of senior organisational leadership.

Research limitations/implications

The participant contributions of personal observations and unfolding real life stories which meld personal common sense with local meaning have formed a unique local ontology therefore allowing for a deeper understanding of the contributing factors toward being in the “middle”. Some of these perspectives have been used by the author's own organisation in the development of leadership training for future organisational change, particularly those aspects concerning communication and participation that are tailored to meet the unique needs of management and staff.

Practical implications

For middle change leaders the focussed examination of the working relationship between middle change leaders and staff groups might prove to be a rich area of further study. These relationships take a variety of forms, including where a staff member has risen through the ranks (off the shop floor as it were) to take on the mantle of leadership, or simply where there is a shared understanding based on subject or professional backgrounds which binds the two together. Further investigation into these relationships may provide perspectives that enable leaders to develop a greater understanding of how change occurs.

Originality/value

The paper shows how the participants locate themselves as being “very much” in the middle in terms of line management of both resources and academic matters and often as being caught between competing imperatives, institutional dynamics and institutional structures.
Promoting empathy in social care for older people
Authors: Strandberg Thomas , Eklund Jakob , Manthorpe Jill
Published: August 2012

Purpose

The purpose of this paper is to identify connections between empathy and social care and to describe aspects of empathy in social care work, by bringing together research from different fields.

Design/methodology/approach

Five doctoral theses which discussed empathy among care workers of older people in Sweden were analysed as a group. The theses had been published over the period 1996 to 2007. Methodologically, the examination underpinned an interpretive content analysis.

Findings

The meta‐analysis revealed conflicting feelings among care workers. Most experienced frustration when they were not able to express empathy in their working practices. Empathy was typically hindered by lack of time, care workers' own needs, and inflexible home care systems. However, a key element of the job‐satisfaction reported by care workers appeared to be its empathic nature. Most care workers perceive encounters with older people as opportunities to respond empathically rather than indifferently. The implications of these findings are discussed.

Originality/value

The study is an overview that attempts to build a bridge across the two concepts, social care and empathy. The main strength of this analysis is its originality of approach undertaking a specific literature review and reflecting on a subject that has not previously been explored in the Swedish context.