bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiple Antibiotic Resistance in Arabidopsis Is Conferred by Mutations in a Chloroplast-Localized Transport Protein
Authors: Conte Sarah , Stevenson David , Furner Ian , Lloyd Alan 
Published: August 2009

Abstract
Widespread antibiotic resistance is a major public health concern, and plants represent an emerging antibiotic exposure route. Recent studies indicate that crop plants fertilized with antibiotic-laden animal manure accumulate antibiotics; however, the molecular mechanisms of antibiotic entry and subcellular partitioning within plant cells remain unknown. Here, we report that mutations in the Arabidopsis (Arabidopsis thaliana) locus Multiple Antibiotic Resistance1 (MAR1) confer resistance, while MAR1 overexpression causes hypersensitivity to multiple aminoglycoside antibiotics. Additionally, yeast expressing MAR1 are hypersensitive to the aminoglycoside G418. MAR1 encodes a protein with 11 putative transmembrane domains with low similarity to ferroportin1 from Danio rerio. A MAR1:yellow fluorescent protein fusion localizes to the chloroplast, and chloroplasts from plants overexpressing MAR1 accumulate more of the aminoglycoside gentamicin, while mar1-1 mutant chloroplasts accumulate less than the wild type. MAR1 overexpression lines are slightly chlorotic, and chlorosis is rescued by exogenous iron. MAR1 expression is also down-regulated by low iron. These data suggest that MAR1 is a plastid transporter that is likely to be involved in cellular iron homeostasis and allows opportunistic entry of multiple antibiotics into the chloroplast.
Conservation of Lotus and Arabidopsis Basic Helix-Loop-Helix Proteins Reveals New Players in Root Hair Development
Authors: Karas Bogumil , Amyot Lisa , Johansen Christopher , Sato Shusei , Tabata Satoshi , Kawaguchi Masayoshi , Szczyglowski Krzysztof 
Published: August 2009

Abstract
Basic helix-loop-helix (bHLH) proteins constitute a large family of transcriptional regulators in plants. Although they have been shown to play important roles in a wide variety of developmental processes, relatively few have been functionally characterized. Here, we describe the map-based cloning of the Lotus japonicus ROOTHAIRLESS1 (LjRHL1) locus. Deleterious mutations in this locus prevent root hair development, which also aborts root hair-dependent colonization of the host root by nitrogen-fixing bacteria. We show that the LjRHL1 gene encodes a presumed bHLH transcription factor that functions in a nonredundant manner to control root hair development in L. japonicus. Homology search and cross-species complementation experiments defined three members of the Arabidopsis (Arabidopsis thaliana) bHLH protein family, At2g24260, At4g30980, and At5g58010, as functionally equivalent to LjRHL1. Curiously, At2g24260 and At4g30980 mRNA species accumulate independently from the known positive regulators of root hair cell fate, while all three genes act in a partially redundant manner to regulate root hair development in Arabidopsis.
Stem cell donation – What advice can be given to the donor?
Authors: Pamphilon Derwood , Siddiq Samreen , Brunskill Susan , Dorée Carolyn , Hyde Chris , Horowitz Mary , Stanworth Simon 
Published: August 2009

SummaryHaematopoietic stem cell transplantation (HSCT) is widely used to treat patients with a range of haematological and non‐haematological disorders. Both bone marrow and peripheral blood stem cell collection are associated with morbidity and, very rarely, mortality. We investigated the information that exists to adequately inform donors about the relative merits of each procedure. We carried out a systematic review analysing data from six prospective randomised controlled trials of related donors and discuss here the merits and drawbacks of this approach. Registry data mostly describes patient outcome but stem cell donor registries collect and report information on unrelated donors which could easily be extended to related donors. Further well‐designed, randomised studies are required.
The response of periphyton and submerged macrophytes to nitrogen and phosphorus loading in shallow warm lakes: a mesocosm experiment
Authors: ÖZKAN KORHAN , JEPPESEN ERIK , JOHANSSON LISELOTTE S. , BEKLIOGLU MERYEM 
Published: August 2009

Summary1. Recent experimental and field studies on temperate shallow lakes indicate that nitrogen may play a greater role in their functioning than previously thought. Several studies document that abundance and richness of submerged macrophytes, both central in shallow lake ecology, may decrease with increasing nitrogen loading, especially at high phosphorus levels. However, the role of nitrogen in warm lakes with fluctuating water regimes remains to be described in detail.2. The effect of increasing nitrate and phosphate concentrations on submerged macrophyte growth was examined in a 3‐month mesocosm experiment conducted in summer in a shallow freshwater lake on the north western coast of Turkey with a Mediterranean climate. Twenty four field mesocosms, open to the sediment and atmosphere, were stocked with Myriophyllum spicatum shoots and small cyprinid fish. Three nitrate loadings in combination with two phosphate loadings were applied in a fourfold replicated design.3. Mean ± SD nutrient concentrations maintained throughout the experiment were 0.55 ± 0.17, 2.2 ± 0.97, 9.2 ± 5.45 mg L−1 total nitrogen and 55 ± 19.2, 73 ± 22.9 μg L−1 total phosphorus. Mean periphyton biomass increased with increasing nutrient concentrations and peaked at the highest nitrogen and phosphorus loadings, while the mean phytoplankton biomass remained relatively low in all treatments.4. Percent volume inhabited (% PVI) by macrophytes throughout the experiment and total macrophyte biomass at the end of the experiment did not differ among treatments. In addition to stocked M. spicatum, Ceratophyllum demersum and Potamogeton crispus appeared in the majority of the mesocosms. The plants grew continuously up to 50% PVI throughout the experiment and remained resilient to shading provided by periphyton and phytoplankton.5. The mean summer air temperature in 2007 was 2.2 °C higher than the average of the last 32 years, which resulted in a water level decrease of 0.3 m in the mesocosms over three months. This might have counteracted the shading of submerged macrophytes provided by phytoplankton and periphyton. The results of the experiment are consistent with observations of higher macrophyte resilience to nutrient loading in Mediterranean lakes compared with northern temperate lakes.
Lithology and hydrocarbon mapping from multicomponent seismic data
Authors: Özdemir Hüseyin , Flanagan Kevin , Tyler Emma 
Published: August 2009

ABSTRACTElastic rock properties can be estimated from prestack seismic data using amplitude variation with offset analysis. P‐wave, S‐wave and density ‘reflectivities’, or contrasts, can be inverted from angle‐band stacks. The ‘reflectivities’ are then inverted to absolute acoustic impedance, shear impedance and density. These rock properties can be used to map reservoir parameters through all stages of field development and production. When P‐wave contrast is small, or gas clouds obscure reservoir zones, multicomponent ocean‐bottom recording of converted‐waves (P to S or Ps) data provides reliable mapping of reservoir boundaries.Angle‐band stacks of multicomponent P‐wave (Pz) and Ps data can also be inverted jointly. In this paper Aki‐Richards equations are used without simplifications to invert angle‐band stacks to ‘reflectivities’. This enables the use of reflection seismic data beyond 30° of incident angles compared to the conventional amplitude variation with offset analysis. It, in turn, provides better shear impedance and density estimates. An important input to amplitude variation with offset analysis is theVs/Vpratio. Conventional methods use a constant or a time‐varyingVs/Vpmodel. Here, a time‐ and space‐varying model is used during the computation of the ‘reflectivities’. TheVs/Vpmodel is generated using well log data and picked horizons. For multicomponent data applications, the latter model can also be generated from processingVs/Vpmodels and available well data.Reservoir rock properties such as λρ, μρ, Poisson's ratio and bulk modulus can be computed from acoustic impedance, shear impedance and density for pore fill and lithology identification. λ and μ are the Lamé constants and ρ is density. These estimations can also be used for a more efficient log property mapping.Vp/Vsratio or Poisson's ratio, λρ and weighted stacks, such as the one computed from λρ and λ/μ, are good gas/oil and oil/water contact indicators, i.e., pore fill indicators, while μρ mainly indicates lithology. μρ is also affected by pressure changes.Results from a multicomponent data set are used to illustrate mapping of gas, oil and water saturation and lithology in a Tertiary sand/shale setting. Whilst initial log crossplot analysis suggested that pore fill discrimination may be possible, the inversion was not successful in revealing fluid effects. However, rock properties computed from acoustic impedance, shear impedance and density estimates provided good lithology indicators; pore fill identification was less successful. Neural network analysis using computed rock properties provided good indication of sand/shale distribution away from the existing wells and complemented the results depicted from individual rock property inversions.
Changes in fire regime break the legacy lock on successional trajectories in Alaskan boreal forest
Authors: JOHNSTONE JILL F. , HOLLINGSWORTH TERESA N. , CHAPIN F. STUART , MACK MICHELLE C. 
Published: August 2009

AbstractPredicting plant community responses to changing environmental conditions is a key element of forecasting and mitigating the effects of global change. Disturbance can play an important role in these dynamics, by initiating cycles of secondary succession and generating opportunities for communities of long‐lived organisms to reorganize in alternative configurations. This study used landscape‐scale variations in environmental conditions, stand structure, and disturbance from an extreme fire year in Alaska to examine how these factors affected successional trajectories in boreal forests dominated by black spruce. Because fire intervals in interior Alaska are typically too short to allow relay succession, the initial cohorts of seedlings that recruit after fire largely determine future canopy composition. Consequently, in a dynamically stable landscape, postfire tree seedling composition should resemble that of the prefire forest stands, with little net change in tree composition after fire. Seedling recruitment data from 90 burned stands indicated that postfire establishment of black spruce was strongly linked to environmental conditions and was highest at sites that were moist and had high densities of prefire spruce. Although deciduous broadleaf trees were absent from most prefire stands, deciduous trees recruited from seed at many sites and were most abundant at sites where the fires burned severely, consuming much of the surface organic layer. Comparison of pre‐ and postfire tree composition in the burned stands indicated that the expected trajectory of black spruce self‐replacement was typical only at moist sites that burned with low fire severity. At severely burned sites, deciduous trees dominated the postfire tree seedling community, suggesting these sites will follow alternative, deciduous‐dominated trajectories of succession. Increases in the severity of boreal fires with climate warming may catalyze shifts to an increasingly deciduous‐dominated landscape, substantially altering landscape dynamics and ecosystem services in this part of the boreal forest.
The influence of elevated temperature, elevated atmospheric CO2 concentration and water stress on net photosynthesis of loblolly pine (Pinus taeda L.) at northern, central and southern sites in its native range
Authors: WERTIN TIMOTHY M. , MCGUIRE MARY ANNE , TESKEY ROBERT O. 
Published: August 2009

AbstractWe investigated the effect of elevated [CO2] (700 μmol mol−1), elevated temperature (+2 °C above ambient) and decreased soil water availability on net photosynthesis (Anet) and water relations of one‐year old potted loblolly pine (Pinus taeda L.) seedlings grown in treatment chambers with high fertility at three sites along a north‐south transect covering a large portion of the species native range. At each location (Blairsville, Athens and Tifton, GA) we constructed four treatment chambers and randomly assigned each chamber one of four treatments: ambient [CO2] and ambient temperature, elevated [CO2] and ambient temperature, ambient [CO2] and elevated temperature, or elevated [CO2] and elevated temperature. Within each chamber half of the seedlings were well watered and half received much less water (1/4 that of the well watered).Measurements of net photosynthesis (Anet), stomatal conductance (gs), leaf water potential and leaf fluorescence were made in June and September, 2008. We observed a significant increase in Anet in response to elevated [CO2] regardless of site or temperature treatment in June and September. An increase in air temperature of over 2 °C had no significant effect on Anet at any of the sites in June or September despite over a 6 °C difference in mean annual temperature between the sites. Decreased water availability significantly reduced Anet in all treatments at each site in June. The effects of elevated [CO2] and temperature on gs followed a similar trend. The temperature, [CO2] and water treatments did not significantly affect leaf water potential or chlorophyll fluorescence. Our findings suggest that predicted increases in [CO2] will significantly increase Anet, while predicted increases in air temperature will have little effect on Anet across the native range of loblolly pine. Potential decreases in precipitation will likely cause a significant reduction in Anet, though this may be mitigated by increased [CO2].
Mutations in the cinnamate 4‐hydroxylase gene impact metabolism, growth and development in Arabidopsis
Authors: Schilmiller Anthony L. , Stout Jake , Weng Jing‐Ke , Humphreys John , Ruegger Max O. , Chapple Clint 
Published: August 2009

SummaryThe initial reactions of the phenylpropanoid pathway convert phenylalanine to p‐coumaroyl CoA, a branch point metabolite from which many phenylpropanoids are made. Although the second enzyme of this pathway, cinnamic acid 4‐hydroxylase (C4H), is well characterized, a mutant for the gene encoding this enzyme has not yet, to our knowledge, been identified, presumably because knock‐out mutations in this gene would have severe phenotypes. This work describes the characterization of an allelic series of Arabidopsis reduced epidermal fluorescence 3 (ref3) mutants, each of which harbor mis‐sense mutations in C4H (At2g30490). Heterologous expression of the mutant proteins in Escherichia coli yields enzymes that exhibit P420 spectra, indicative of mis‐folded proteins, or have limited ability to bind substrate, indicating that the mutations we have identified affect protein stability and/or enzyme function. In agreement with the early position of C4H in phenylpropanoid metabolism, ref3 mutant plants accumulate decreased levels of several different classes of phenylpropanoid end‐products, and exhibit reduced lignin deposition and altered lignin monomer content. Furthermore, these plants accumulate a novel hydroxycinnamic ester, cinnamoylmalate, which is not found in the wild type. The decreased C4H activity in ref3 also causes pleiotropic phenotypes, including dwarfism, male sterility and the development of swellings at branch junctions. Together, these observations indicate that C4H function is critical to the normal biochemistry and development of Arabidopsis.
Recombineering and stable integration of the Pseudomonas syringae pv. syringae 61 hrp/hrc cluster into the genome of the soil bacterium Pseudomonas fluorescens Pf0‐1
Authors: Thomas William J. , Thireault Caitlin A. , Kimbrel Jeffrey A. , Chang Jeff H. 
Published: August 2009

SummaryMany Gram‐negative bacteria use a type III secretion system (T3SS) to establish associations with their hosts. The T3SS is a conduit for direct injection of type‐III effector proteins into host cells, where they manipulate the host for the benefit of the infecting bacterium. For plant‐associated pathogens, the variations in number and amino acid sequences of type‐III effectors, as well as their functional redundancy, make studying type‐III effectors challenging. To mitigate this challenge, we developed a stable delivery system for individual or defined sets of type‐III effectors into plant cells. We used recombineering and Tn5‐mediated transposition to clone and stably integrate, respectively, the complete hrp/hrc region from Pseudomonas syringae pv. syringae 61 into the genome of the soil bacterium Pseudomonas fluorescens Pf0‐1. We describe our development of Effector‐to‐Host Analyzer (EtHAn), and demonstrate its utility for studying effectors for their in planta functions.
Tethering of ferredoxin:NADP+ oxidoreductase to thylakoid membranes is mediated by novel chloroplast protein TROL
Authors: Jurić Snježana , Hazler‐Pilepić Kroata , Tomašić Ana , Lepeduš Hrvoje , Jeličić Branka , Puthiyaveetil Sujith , Bionda Tihana , Vojta Lea , Allen John F. , Schleiff Enrico , Fulgosi Hrvoje 
Published: August 2009

SummaryWorking in tandem, two photosystems in the chloroplast thylakoid membranes produce a linear electron flow from H2O to NADP+. Final electron transfer from ferredoxin to NADP+ is accomplished by a flavoenzyme ferredoxin:NADP+ oxidoreductase (FNR). Here we describe TROL (thylakoid rhodanese‐like protein), a nuclear‐encoded component of thylakoid membranes that is required for tethering of FNR and sustaining efficient linear electron flow (LEF) in vascular plants. TROL consists of two distinct modules; a centrally positioned rhodanese‐like domain and a C‐terminal hydrophobic FNR binding region. Analysis of Arabidopsis mutant lines indicates that, in the absence of TROL, relative electron transport rates at high‐light intensities are severely lowered accompanied with significant increase in non‐photochemical quenching (NPQ). Thus, TROL might represent a missing thylakoid membrane docking site for a complex between FNR, ferredoxin and NADP+. Such association might be necessary for maintaining photosynthetic redox poise and enhancement of the NPQ.
Queer Quit: Gay smokers’ perspectives on a culturally specific smoking cessation service
Authors: Schwappach David L.B. 
Published: August 2009

AbstractBackground  The prevalence of smoking is high among gay males. The need for culturally specific support has been acknowledged, but little is known about gay men’s perspectives on such adapted interventions.Objective  To investigate smoking and intention to quit in gay smokers and to explore their attitudes towards a gay‐specific smoking cessation programme.Design  Quantitative survey and focus groups.Setting and participants  A total of 325 gay smokers living in Zurich (Switzerland) completed an anonymous survey. Thirteen males participated in two focus groups, theoretically sampled to reflect heterogeneity in terms of age, HIV serostatus and smoking histories. Participants were personally recruited at a variety of events and through advertisements.Results  Responders reported high consumption of cigarettes, and every second man stated that more than half of his gay friends smoke regularly. The majority planned their quit within the next 6 months. Idealizing attitudes towards smoking were very common. Men stated strong preferences towards a culturally adapted cessation programme for gay men. Higher age, high nicotine dependence, intention to quit, smoking stereotypes and fears for weight gain were significant predictors for interest in participation in the programme. Qualitative results indicate that men felt torn between their wish for support, bonding, and community alternatives to the ‘smoking gay’ environment and fears for failure and loss of reputation.Conclusions  Gay men reported likely use of a gay‐specific intervention. Such interventions may offer support in abstaining from smoking, without abstaining from gay social life. Health‐care providers play an important role in communicating the serious threats caused by smoking to gay men.
Exciting but exhausting: experiences with participatory research with chronically ill adolescents
Authors: Van Staa AnneLoes , Jedeloo Susan , Latour Jos M , Trappenburg Margo J 
Published: August 2009

AbstractBackground  Adolescents with chronic conditions are major users of paediatric hospitals, but seldom participate in the evaluation of services or in research. Little is known about the usefulness of the participatory approach in adolescent health research.Objective  To evaluate the feasibility, benefits and limitations of a participatory research (PR) project involving chronically ill adolescents as co‐researchers.Design, setting and participants  Nine adolescents, aged 15–17 years, acted as co‐researchers in a hospital‐based PR project. They co‐developed an interview protocol and during a disco party held for this purpose interviewed each other and 25 fellow patients (12–19 years). They provided advice on the draft report and participated in the dissemination of the results, but were not involved in the design of the project or analysis of results.Results  Involving adolescents in participatory health research was feasible and appreciated by researchers and youth alike, but had its drawbacks too. The peer‐research attracted few participants, the interviews lacked depth and did not yield substantial new insights. Maintaining a high level of participation of the chronically ill co‐researchers also proved difficult.Conclusions  Adolescents with chronic conditions like to have a say in the design and evaluation of hospital services. But their participation as co‐researchers demands ample resources from all parties involved without automatically improving research quality. PR does not seem the most effective and efficient way to make services more responsive. We therefore recommend further exploration of other creative and sustainable ways for involving youth in health‐care service development and innovation.
Glutamine administration in patients undergoing cardiac surgery and the influence on blood glutathione levels
Authors: ENGEL J. M. , MÜHLING J. , KWAPISZ M. , HEIDT M. 
Published: August 2009

Background: Cardiac surgery with an extracorporeal circulation cardiopulmonary bypass (CPB) is characterized by an oxidative stress response. Glutathione (GSH) belongs to the major antioxidative defense. In metabolic stress, glutamine (GLN) may be the rate‐limiting factor of GSH synthesis. Decreased GLN plasma levels were observed after various critical states. We evaluated, in patients undergoing open heart surgery with CPB, the effects of a peri‐operative GLN supplementation on GSH in whole blood and assessed their influence on the Sequential Organ Failure Assessment score and the intensive care unit length of stay.Methods: In this prospective, randomized, double‐blinded study, we included 60 patients (age older than 70 years, ejection fraction <40% or mitral valve replacement) undergoing an elective cardiac surgery with CPB. We randomly assigned each subject to receive an infusion with either GLN (0.5 g/kg/day, group 1) or an isonitrogeneous, isocaloric, isovolemic amino acids solution (group 2) or saline (group 3).Results: From the first post‐operative day GLN plasma levels in group 1 were significantly increased compared with the other groups. With saline GSH the levels decreased significantly post‐operatively compared with GLN. We observed a significant correlation between GLN delivery and GSH levels.Conclusions: A peri‐operative high‐dose GLN infusion increased plasma GLN concentrations and maintained the GSH levels after cardiac surgery with CPB.