bluuebunny/crossref_metadata_2025_split huggingface dataset:
Collective learning, change and improvement in health care: trialling a facilitated learning initiative with general practice teams
Authors: Bunniss Suzanne , Gray Francesca , Kelly Diane 
Published: February 2011

AbstractRationale, aims and objectives  Many patients, families, health care professionals and politicians desire for quality improvement within the UK National Health Service. One way to achieve this change is for health care teams to work and learn together more effectively. This research aimed to design and trial a facilitated learning programme with the aim of supporting general practice teams in fostering the characteristics of learning organizations.Methods  This is an action research study. Qualitative data were captured during and after the trial from 40 participants in two multi‐professional general practice teams within different Scottish health boards. Data were gathered using observations, semi‐structured interviews and written learning notes.Results  Taking part in the LPP was a positive experience of learning together as a practice and enhanced communication within the team was a particular outcome. External facilitation helped provide focus and reduce inter‐professional barriers. Teams found working in small, mixed role discussion groups particularly valuable in understanding each others' perspectives. The active learning style of the LPP could be daunting at times but teams valued the chance to identify their own quality improvement goals. Teams introduced a number of changes to improve the quality of care within their practice as a result of their participation.Conclusion  This trial of the learning practice programme shows that, with facilitation and the appropriate input of resources, general practice teams can successfully apply learning organization principles to produce quality improvement outcomes. The study also demonstrates the value of action research in researching iterative change over time.
Adaptive evolution of the Populus tremula photoperiod pathway
Authors: HALL DAVID , MA XIAO‐FEI , INGVARSSON PÄR K. 
Published: February 2011

AbstractPerennial plants monitor seasonal changes through changes in environmental conditions such as the quantity and quality of light and genes in the photoperiodic pathway are known to be involved in controlling these processes. Here, we examine 25 of genes from the photoperiod pathway in Populus tremula (Salicaceae) for signatures of adaptive evolution. Overall, levels of synonymous polymorphism in the 25 genes are lower than at control loci selected randomly from the genome. This appears primarily to be caused by lower levels of synonymous polymorphism in genes associated with the circadian clock. Natural selection appears to play an important role in shaping protein evolution at several of the genes in the photoperiod pathways, which is highlighted by the fact that approximately 40% of the genes from the photoperiod pathway have estimates of selection on nonsynonymous polymorphisms that are significantly different from zero. A surprising observation we make is that circadian clock‐associated genes appear to be over‐represented among the genes showing elevated rates of protein evolution; seven genes are evolving under positive selection and all but one of these genes are involved in the circadian clock of Populus.
Transgenic poplars with reduced lignin show impaired xylem conductivity, growth efficiency and survival
Authors: VOELKER STEVEN L. , LACHENBRUCH BARBARA , MEINZER FREDERICK C. , KITIN PETER , STRAUSS STEVEN H. 
Published: February 2011

ABSTRACTWe studied xylem anatomy and hydraulic architecture in 14 transgenic insertion events and a control line of hybrid poplar (Populus spp.) that varied in lignin content. Transgenic events had different levels of down‐regulation of two genes encoding 4‐coumarate:coenzyme A ligase (4CL). Two‐year‐old trees were characterized after growing either as free‐standing trees in the field or as supported by stakes in a greenhouse. In free‐standing trees, a 20 to 40% reduction in lignin content was associated with increased xylem vulnerability to embolism, shoot dieback and mortality. In staked trees, the decreased biomechanical demands on the xylem was associated with increases in the leaf area to sapwood area ratio and wood specific conductivity (ks), and with decreased leaf‐specific conductivity (kl). These shifts in hydraulic architecture suggest that the bending stresses perceived during growth can affect traits important for xylem water transport. Severe 4CL‐downregulation resulted in the patchy formation of discoloured, brown wood with irregular vessels in which water transport was strongly impeded. These severely 4CL‐downregulated trees had significantly lower growth efficiency (biomass/leaf area). These results underscore the necessity of adequate lignification for mechanical support of the stem, water transport, tree growth and survival.
Circadian photosynthetic reductant flow in the dinoflagellate Lingulodinium is limited by carbon availability
Authors: MACKENZIE TYLER D. B. , MORSE DAVID 
Published: February 2011

ABSTRACTCircadian rhythms are the observed outputs of endogenous daily clocks and are thought to provide a selective advantage to cells adapted to daily light/dark cycles. However, the biochemical links between the clock and the overt rhythms in cell physiology are generally not known. Here, we examine the circadian rhythm in O2 evolution by cultures of the dinoflagellate Lingulodinium, a rhythm previously ascribed to rhythmic electron flow through photosystem II. We find that O2 evolution rates increase when CO2 concentrations are increased, either following addition of DIC or a rapid decrease in culture pH. In medium containing only nitrate as an electron acceptor, O2 evolution rates mirror the circadian rhythm of nitrate reductase activity in the cells. Furthermore, competition between photosynthetic electron flow to carbon and to nitrate varies in its relative efficiency through the day–night cycle. We also find, using simultaneous and continuous monitoring of pH and O2 evolution rates over several days, that while culture pH is normally rhythmic, circadian changes in rates of O2 evolution depend not on the external pH but on levels of internal electron acceptors. We propose that the photosynthetic electron transport rhythm in Lingulodinium is driven by the availability of a reductant sink.
Proton‐coupled high‐affinity phosphate transport revealed from heterologous characterization in Xenopus of barley‐root plasma membrane transporter, HvPHT1;1
Authors: PREUSS CHRISTIAN P. , HUANG CHUN Y. , TYERMAN STEPHEN D. 
Published: February 2011

ABSTRACTHigh‐affinity phosphate transporters mediate uptake of inorganic phosphate (Pi) from soil solution under low Pi conditions. The electrophysiological properties of any plant high‐affinity Pi transporter have not been described yet. Here, we report the detailed characterization of electrophysiological properties of the barley Pi transporter, HvPHT1;1 in Xenopus laevis oocytes. A very low Km value (1.9 µm) for phosphate transport was observed in HvPHT1;1, which falls within the concentration range observed for barley roots. Inward currents at negative membrane potentials were identified as nH+:Pi‐ (n > 1) co‐transport based on simultaneous Pi radiotracer uptake, oocyte voltage clamping and pH dependence. HvPHT1;1 showed preferential selectivity for Pi and arsenate, but no transport of the other oxyanions SO42− and NO3‐. In addition, HvPHT1;1 locates to the plasma membrane when expressed in onion (Allium cepa L.) epidermal cells, and is highly expressed in root segments with dense hairs. The electrophysiological properties, plasma membrane localization and cell‐specific expression pattern of HvPHT1;1 support its role in the uptake of Pi under low Pi conditions.
Hydraulic conductivity of red oak (Quercus rubra L.) leaf tissue does not respond to light
Authors: ROCKWELL F. E. , HOLBROOK N. M. , ZWIENIECKI M. A. 
Published: February 2011

ABSTRACTThe permeability of leaf tissue to water has been reported to increase under illumination, a response reputed to involve aquaporins. We studied this ‘light response’ in red oak (Quercus rubra L.), the species in which the phenomenon was first detected during measurements of leaf hydraulic conductance with the high‐pressure flow meter (HPFM). In our HPFM measurements, we found that pre‐conditioning leaves in darkness was not sufficient to bring them to their minimum conductance, which was attained only after an hour of submersion and pressurization. However, pre‐conditioning leaves under anoxic conditions resulted in an immediate reduction in conductance. Leaves light‐ and dark‐acclimated while on the tree showed no differences in the time course of HPFM measurement under illumination. We also studied the effect of light level and anoxia on rehydration kinetics, finding that anoxia slowed rehydration, but light had no effect either in the lab (rehydration under low light, high humidity) or on the tree (acclimation under high light, 10 min of dark prior to rehydration). We conclude that the declines in conductance observed in the HPFM must involve a resistance downstream of the extracellular air space, and that in red oak the hydraulic conductivity of leaf tissue is insensitive to light.
Foliar and soil δ15N values reveal increased nitrogen partitioning among species in diverse grassland communities
Authors: GUBSCH MARLÉN , ROSCHER CHRISTIANE , GLEIXNER GERD , HABEKOST MAIKE , LIPOWSKY ANNETT , SCHMID BERNHARD , SCHULZE ERNST‐DETLEF , STEINBEISS SIBYLLE , BUCHMANN NINA 
Published: February 2011

ABSTRACTPlant and soil nitrogen isotope ratios (δ15N) were studied in experimental grassland plots of varying species richness. We hypothesized that partitioning of different sources of soil nitrogen among four plant functional groups (legumes, grasses, small herbs, tall herbs) should increase with diversity. Four years after sowing, all soils were depleted in 15N in the top 5 cm whereas in non‐legume plots soils were enriched in 15N at 5–25 cm depth. Decreasing foliar δ15N and Δδ15N (= foliar δ15N − soil δ15N) values in legumes indicated increasing symbiotic N2 fixation with increasing diversity. In grasses, foliar Δδ15N also decreased with increasing diversity suggesting enhanced uptake of N depleted in 15N. Foliar Δδ15N values of small and tall herbs were unaffected by diversity. Foliar Δδ15N values of grasses were also reduced in plots containing legumes, indicating direct use of legume‐derived N depleted in 15N. Increased foliar N concentrations of tall and small herbs in plots containing legumes without reduced foliar δ15N indicated that these species obtained additional mineral soil N that was not consumed by legumes. These functional group and species specific shifts in the uptake of different N sources with increasing diversity indicate complementary resource use in diverse communities.
The water–water cycle in leaves is not a major alternative electron sink for dissipation of excess excitation energy when CO2 assimilation is restricted
Authors: DRIEVER STEVEN M. , BAKER NEIL R. 
Published: February 2011

ABSTRACTElectron flux from water via photosystem II (PSII) and PSI to oxygen (water–water cycle) may provide a mechanism for dissipation of excess excitation energy in leaves when CO2 assimilation is restricted. Mass spectrometry was used to measure O2 uptake and evolution together with CO2 uptake in leaves of French bean and maize at CO2 concentrations saturating for photosynthesis and the CO2 compensation point. In French bean at high CO2 and low O2 concentrations no significant water–water cycle activity was observed. At the CO2 compensation point and 3% O2 a low rate of water–water cycle activity was observed, which accounted for 30% of the linear electron flux from water. In maize leaves negligible water–water cycle activity was detected at the compensation point. During induction of photosynthesis in maize linear electron flux was considerably greater than CO2 assimilation, but no significant water–water cycle activity was detected. Miscanthus × giganteus grown at chilling temperature also exhibited rates of linear electron transport considerably in excess of CO2 assimilation; however, no significant water–water cycle activity was detected. Clearly the water–water cycle can operate in leaves under some conditions, but it does not act as a major sink for excess excitation energy when CO2 assimilation is restricted.
Toward the mechanism of NH4+ sensitivity mediated by Arabidopsis GDP‐mannose pyrophosphorylase
Authors: KEMPINSKI CHASE F. , HAFFAR RAWAA , BARTH CARINA 
Published: February 2011

ABSTRACTThe ascorbic acid (AA)‐deficient Arabidopsis thaliana mutant vtc1‐1, which is defective in GDP‐mannose pyrophosphorylase (GMPase), exhibits conditional hypersensitivity to ammonium (NH4+), a phenomenon that is independent of AA deficiency. As GMPase is important for GDP‐mannose biosynthesis, a nucleotide sugar necessary for protein N‐glycosylation, it has been thought that GDP‐mannose deficiency is responsible for the growth defect in vtc1‐1 in the presence of NH4+. Therefore, the motivation for this work was to elucidate the growth and developmental processes that are affected in vtc1‐1 in the presence of NH4+ and to determine whether GDP‐mannose deficiency generally causes NH4+ sensitivity. Furthermore, as NH4+ may alter cytosolic pH, we investigated the responses of vtc1‐1 to pH changes in the presence and absence of NH4+. Using qRT‐PCR and staining procedures, we demonstrate that defective N‐glycosylation in vtc1‐1 contributes to cell wall, membrane and cell cycle defects, resulting in root growth inhibition in the presence of NH4+. However, by using mutants acting upstream of vtc1‐1 and contributing to GDP‐mannose biosynthesis, we show that GDP‐mannose deficiency does not generally lead to and is not the primary cause of NH4+ sensitivity. Instead, our data suggest that GMPase responds to pH alterations in the presence of NH4+.
Development of a hydrothermal time model that accurately characterises how thermoinhibition regulates seed germination
Authors: WATT M. S. , BLOOMBERG M. , FINCH‐SAVAGE W. E. 
Published: February 2011

ABSTRACTThermoinhibition is the decline in germinability within a seed population as soil temperatures increase above the optimum for germination. Hydrothermal time (HTT) models have been developed that describe the thermoinhibition response as a function of increases in the threshold water potential for seed germination [seed base water potential, Ψb(G)]. Although these models assume a normal distribution of Ψb(G) and a linear upward shift in Ψb(G) with increasing temperature, little research has tested these assumptions. Using germination data obtained from four unrelated plant species, we fitted HTT models that use the Weibull and normal distribution to describe Ψb(G) and compared the accuracy and bias of these two HTT models. For all four species, Ψb(G) and germination were more accurately described by the Weibull than the normal distribution HTT model. At supra‐optimal temperatures, Ψb(G) of the earliest germinating seeds showed little thermoinhibition effect so that the seeds germinated very rapidly under moist conditions. However, for the rest of the population, Ψb(G) increased progressively in response to supra‐optimal temperatures so that the slower germinating seeds were thermoinhibited. The fitted HTT models reveal aspects of seed thermoinhibition that appear to have adaptational value under variable conditions of soil temperature and moisture.
Genetic structure and diversity of Phakopsora pachyrhizi isolates from soyabean
Authors: Twizeyimana M. , Ojiambo P. S. , Haudenshield J. S. , Caetano‐Anollés G. , Pedley K. F. , Bandyopadhyay R. , Hartman G. L. 
Published: February 2011

Simple sequence repeat (SSR) markers were used to classify 116 isolates of Phakopsora pachyrhizi, the cause of soyabean rust, collected from infected soyabean leaves in four agroecological zones in Nigeria. A high degree of genetic variation was observed within the sampled populations of P. pachyrhizi. Eighty‐four distinct genotypes were identified among three of the four agroecological zones. Nei’s average genetic diversity across geographical regions was 0·22. Hierarchical analysis of molecular variance showed low genetic differentiation among all populations of P. pachyrhizi. The majority (> 90%) of the genetic diversity was distributed within each soyabean field, while approximately 6% of the genetic diversity was distributed among fields within geographic regions. Low population differentiation was indicated by the low FST values among populations, suggesting a wide dispersal of identical genotypes on a regional scale. Phylogenetic analysis indicated a strictly clonal structure of the populations and five main groups were observed, with group II accounting for 30% of the entire population. Because of the asexual reproduction of P. pachyrhizi, single‐step mutations in SSR genotypes are likely to account for the genetic differences within each group.
Ditylenchus gigas n. sp. parasitizing broad bean: a new stem nematode singled out from the Ditylenchus dipsaci species complex using a polyphasic approach with molecular phylogeny
Authors: Vovlas N. , Troccoli A. , Palomares‐Rius J. E. , De Luca F. , Liébanas G. , Landa B. B. , Subbotin S. A. , Castillo P. 
Published: February 2011

Morphologial, biochemical, molecular and karyological analyses of different populations and races of the stem and bulb nematode Ditylenchus dipsaci have suggested that it represents a species complex, of which only D. dipsaci sensu stricto and its morphologically larger variant, known as the giant race of the stem and bulb nematode, are plant parasites of economic importance. The present study singles out the giant race from this complex, herein described as a new species named Ditylenchus gigas n. sp., on the basis of morphological and molecular data obtained from several populations collected from broad beans in southern Italy, southern Spain and Lebanon. The new species epithet, which refers to the large body size of the nematode with respect to the normal races, must be considered to be conspecific with the D. dipsaci‘giant race’ from Fabaceae in recent literature. Morphologically, the new species is characterized by a body size 1·5–2 times longer than the ‘normal race’, stylet delicate (11·5–13·0 μm long) with knobs distinctly sloping backwards, and long post‐vulval uterine sac (81–150 μm long). Results of molecular analysis of rDNA sequences including the ITS1‐5.8S‐ITS2 region, the D2–D3 fragment of the 28S gene, the small 18S subunit, the partial mitochondrial gene for cytochrome c oxidase I (mtCOI), and hsp90 gene sequences, support the new taxonomic species status for the former D. dipsaci giant race from Vicia faba, and clearly distinguish D. gigas n. sp. from D. dipsaci sensu stricto.
Molecular characterization of a Stagonospora nodorum lipase gene LIP1
Authors: Feng J. , Hwang R. , Hwang S.‐F. , Gaudet D. , Strelkov S. E. 
Published: February 2011

A triglyceride lipase gene (LIP1) was cloned from Stagonospora nodorum, the causal agent of wheat glume blotch. LIP1 encodes a 561 amino acid preproprotein with a predicted N‐terminal signal peptide. Its expression was up‐regulated during plant infection and in culture media supplemented with saturated fatty glycerides. The recombinant Lip1 protein possessed lipolytic activity against a broad range of lipid substrates. When applied to wheat leaves, recombinant Lip1 decreased the hydrophobicity of the leaf surface, probably by liquefaction of epicuticular wax. Pretreatment of wheat leaves with Lip1 decreased the rate of conidial adhesion from 69·5% to 22·7% and from 58·9% to 28·4% in two independent assays based on different protocols. LIP1 replacement strains showed decreased lipolytic activity on culture media relative to the wild‐type strain, and adhesion of the conidia to the wheat leaf surface was impaired in the gene replacement strains. In two experiments, adhesion rates were 54·3% and 41·6% in the LIP1 replacement strains, as opposed to 77·7% and 66·6%, respectively, in the wild‐type. Collectively, the data demonstrate that the secreted lipase Lip1 is important for the adhesion of S. nodorum infection to wheat leaves.
Endosperm differentiation in barley wild‐type and sex mutants
Authors: Bosnes Marie , Weideman Fredrik , Olsen Odd‐Arne 
Published: February 2011

The cereal endosperm is a storage organ consisting of the central starchy endosperm surrounded by the aleurone layer. In barley, endosperm development is subdivisible into four main stages, i.e. the syncytial (I), the cellularization (II), the differentiation (III) and the maturation stage (IV). During stage I, a multinucleate syncytium is formed, which in stage II develops into the undifferentiated cellular endosperm. During stage III the cells of the endosperm differentiate into two types of aleurone cells (peripheral and modified) and three different starchy endosperm cell types (irregular, prismatic and subaleurone).To elucidate the ontogenetic relationship between the endosperm tissues, the phenotypes of sex (shrunken endosperm mutants expressing xenia) mutant endosperms were studied. These mutants can be classified into two groups, i.e. those in which development is arrested at one of the four wild‐type stages described above, and those with abnormal development with new organizational patterns in the endosperm or with novel cell types. Based on these studies, it is suggested that the two endosperm halves represent cell lines derived from the two daughter nuclei of the primary endosperm nucleus, and that the prismatic starchy endosperm cells arise from a peripheral endosperm meristematic activity during stage III. Finally, a model for the main molecular events underlying the morphogenetic processes is discussed.
The phosphomimetic mutation of an evolutionarily conserved serine residue affects the signaling properties of Rho of plants (ROPs)
Authors: Fodor‐Dunai Csilla , Fricke Inka , Potocký Martin , Dorjgotov Dulguun , Domoki Mónika , Jurca Manuela E. , Ötvös Krisztina , Žárský Viktor , Berken Antje , Fehér Attila 
Published: February 2011

SummaryPlant ROP (Rho of plants) proteins form a unique subgroup within the family of Rho‐type small G‐proteins of eukaryotes. In this paper we demonstrate that the phosphomimetic mutation of a serine residue conserved in all Rho proteins affects the signaling properties of plant ROPs. We found that the S74E mutation in Medicago ROP6 and Arabidopsis ROP4 prevented the binding of these proteins to their plant‐specific upstream activator the plant‐specific ROP nucleotide exchanger (PRONE)‐domain‐containing RopGEF (guanine nucleotide exchange factor) protein and abolished the PRONE‐mediated nucleotide exchange reaction in vitro. Structural modeling supported the hypothesis that potential phosphorylation of the S74 residue interferes with the binding of the PRONE‐domain to the adjacent plant‐specific R76 residue which plays an important role in functional ROP–PRONE interaction. Moreover, we show that while the binding of constitutively active MsROP6 to the effector protein RIC (ROP‐interactive CRIB‐motif‐containing protein) was not affected by the S74E mutation, the capability of this mutated protein to bind and activate the RRK1 kinase in vitro was reduced. These observations are in agreement with the morphology of tobacco pollen tubes expressing mutant forms of yellow fluorescent protein (YFP):MsROP6. The S74E mutation in MsROP6 had no influence on pollen tube morphology and attenuated the phenotype of a constitutively active form of MsROP6. The presented Medicago and Arabidopsis data support the notion that the phosphorylation of the serine residue in ROPs corresponding to S74 in Medicago ROP6 could be a general principle for regulating ROP activation and signaling in plants.