bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies in the transmission of Plasmodium malariae by Anopheles mosquitoes
Authors: Shute P. G. , Maryon M.
Published: June 2009

P. malariae was first used for therapy purposes at Horton in 1928.

Between 1928 and 1945, nine strains have been used. Most of these were from Africa, but some were from Holland, Roumania and South America. The strain from Holland was probably not indigenous to that country.

All transmission experiments carried out between 1928 and 1945 were with Anopheles maculipennis var. atroparvus. Nineteen separate batches of mosquitoes were fed on patients in whose blood parasites believed to be gametocytes were seen. In only six of these batches were any of the mosquitoes found to be infected and then with only scanty oocysts; sporozoites were never found. No patients were infected by the bites of any of these mosquitoes.

In 1947 a colony of A. stephensi (type) was established.

From 1948 to 1950, sixty-eight batches of A. stephensi were fed on patients in whose blood Plasmodium malariae parasites were present. Scanty gametocytes were found in some of these patients, and on occasion mosquitoes which fed on them became infected, but in others no infection occurred.

Other batches of mosquitoes did become infected after feeding on patients in whose blood no typical gametocytes were found even after a prolonged search. Out of sixty-eight batches of mosquitoes fed, infection was seen in twelve batches, in varying degree, but never with more than nine oocysts in an individual mosquito. Two consecutive human anopheline passages with laboratory-bred Anopheles mosquitoes (A. stephehsi type) and induced human carriers are reported.
Ixodes passericola Schulze. A description of the hitherto unknown male and larva, with a re-description of the female and nymph
Authors: Arthur D. R.
Published: June 2009

During the course of an investigation into the host-relationship of Ixodes hexagonus Leach a large number of birds was examined for its occurrence. These all proved negative for this species, but I. passericola Sch. was present on one robin out of 220 examined, on one starling out of eleven, on seventeen great tits out of 163, on twenty blue tits out of 540, and on four nuthatches out of fifty. A detailed report on this aspect is given later.
Bi-criteria velocity minimization of robot manipulators using LVI-based primal-dual neural network and illustrated via PUMA560 robot arm
Authors: Zhang Yunong , Li Kene
Published: June 2009

In this paper, to diminish discontinuity points arising in the infinity-norm velocity minimization scheme, a bi-criteria velocity minimization scheme is presented based on a new neural network solver, i.e., an LVI-based primal-dual neural network. Such a kinematic planning scheme of redundant manipulators can incorporate joint physical limits, such as, joint limits and joint velocity limits simultaneously. Moreover, the presented kinematic planning scheme can be reformulated as a quadratic programming (QP) problem. As a real-time QP solver, the LVI-based primal-dual neural network is developed with a simple piecewise linear structure and high computational efficiency. Computer simulations performed based on a PUMA560 manipulator model are presented to illustrate the validity and advantages of such a bi-criteria velocity minimization neural planning scheme for redundant robot arms.
A survey of the language situation in Zimbabwe
Authors: Mlambo Muzi
Published: May 2009

Is there a Zimbabwean variety of English? If so, who speaks it? Although Zimbabwe is a multilingual speech community, the Shona language, which is composed of dialects and sub-dialects, enjoys numerical dominance because it is spoken by the majority of the Zimbabweans. On the other hand, English, the official language, enjoys status dominance and it occupies a special position in the lives of many Zimbabweans. There is dispute, however, whether English in Zimbabwe is an interlanguage, and its speakers have adopted the native variety as a model, or whether it is better to observe that there are many varieties of English in Zimbabwe which are pragmatically identifiable as Zimbabwean, and that the vast majority of Zimbabweans appear to speak an English which reflects the linguistic characteristics of Shona.
Reforming medical governance in Europe. What is it about institutions?
Authors: BURAU VIOLA , WILSFORD DAVID , FRANCE GEORGE
Published: May 2009

This article presents a cross-national analytical framework for understanding current attempts to reform medical governance – in particular, those by third parties to control the practice of medicine. The framework pays particular attention to the ways in which institutions shape policy reform. The article also outlines the main comparative findings of case studies of selected reforms and associated processes of negotiations in Denmark, Germany, Italy and the United Kingdom. These four countries were selected because they are characterised by theoretically interesting variations in the institutional contexts of medical governance. The analysis suggests that although all the four countries have pushed for more control over the way in which doctors practise medicine, in response to similar imperatives, each country differs in the path it has taken. More specifically, the instruments and techniques brought to bear in each case vary considerably and are directed by a country's political institutions towards a unique path.
Negotiating reform at an arm's length from the state: Disease Management Programmes and the introduction of clinical standards in Germany
Authors: BURAU VIOLA
Published: May 2009

Studies of German health policy often highlight institutional constraints to reform. However, based on a case study of the introduction of clinical standards as part of the Disease Management Programmes for chronic illnesses, this article suggests that negotiating reform at an arm's length from the state can also lead to governance change, although the strengthening of hierarchy is not as prominent as that in some of the countries studied in this special issue. As such, the case of Germany offers interesting insights into the politics of governance change that occur in the shadow, but largely without the direct involvement of the state, which is typical of a corporatist health-care state. In this respect, the analysis identifies three leverages for change. First, the change in medical governance explicitly builds on earlier reforms and gives the reform alliance a competitive edge. Second, the organisations of the joint self-administration, as a more or less open ally of the state, play an influential role throughout the reform process. Importantly and third, this is complemented by the state steering at a distance.
Competition and compromise in negotiating the new governance of medical performance: the clinical governance and revalidation policies in the UK
Authors: FENTON LAURA , SALTER BRIAN
Published: May 2009

This article explores the development of two policies for the governance of medical performance in the UK: the Department of Health's (DH) clinical governance policy and the medical profession's revalidation policy. After discussing the institutional context in which each of these policies emerged, we examine how and why they were constructed. While the clinical governance policy was in large part a swift reaction to high-profile cases of medical misconduct in the late 1990s, revalidation was the profession's response to the politicisation of its self-regulatory apparatus. The profession took notably longer than the DH to piece together its policy as a result of internal disagreements about the role clinical standards should play in the evaluation of a doctor's fitness to practice. Following the Fifth Report of the Shipman Inquiry in late 2004, the government stepped in and eventually introduced legislation that modifies the profession's policy. With clinical governance, the state – via arms-length regulatory organisations – has entered the clinic in new ways, strengthening hierarchy-based forms of governance in the governance of medical performance. However, the success of hierarchical forms of governance is likely to be restricted by the lack of a clear system of sanctioning and the state's reliance on a lengthy chain of command in the National Health Service for the implementation of clinical standards.
Did the Toba volcanic eruption of ∼74 ka B.P. produce widespread glaciation?
Authors: Robock Alan , Ammann Caspar M. , Oman Luke , Shindell Drew , Levis Samuel , Stenchikov Georgiy
Published: May 2009

It has been suggested that the Toba volcanic eruption, approximately 74 ka B.P., was responsible for the extended cooling period and ice sheet advance immediately following it, but previous climate model simulations, using 100 times the amount of aerosols produced by the 1991 Mount Pinatubo eruption, have been unable to produce such a prolonged climate response. Here we conduct six additional climate model simulations with two different climate models, the National Center for Atmospheric Research Community Climate System Model 3.0 (CCSM3.0) and National Aeronautics and Space Administration Goddard Institute for Space Studies ModelE, in two different versions, to investigate additional mechanisms that may have enhanced and extended the forcing and response from such a large supervolcanic eruption. With CCSM3.0 we include a dynamic vegetation model to explicitly calculate the feedback of vegetation death on surface fluxes in response to the large initial reduction in transmitted light, precipitation, and temperature. With ModelE we explicitly calculate the effects of an eruption on stratospheric water vapor and model stratospheric chemistry feedbacks that might delay the conversion of SO2 into sulfate aerosols and prolong the lifetime and radiative forcing of the stratospheric aerosol cloud. To span the uncertainty in the amount of stratospheric injection of SO2, with CCSM3.0 we used 100 times the Pinatubo injection, and with ModelE we used 33, 100, 300, and 900 times the Pinatubo injection without interactive chemistry, and 300 times Pinatubo with interactive chemistry. Starting from a roughly present‐day seasonal cycle of insolation, CO2 concentration, and vegetation, or with 6 ka B.P. conditions for CCSM3.0, none of the runs initiates glaciation. The CCSM3.0 run produced a maximum global cooling of 10 K and ModelE runs produced 8–17 K of cooling within the first years of the simulation, depending on the injection, but in all cases, the climate recovers over a few decades. Nevertheless, the “volcanic winter” following a supervolcano eruption of the size of Toba today would have devastating consequences for humanity and global ecosystems. These simulations support the theory that the Toba eruption indeed may have contributed to a genetic bottleneck.
Electron densities in Jupiter's outer magnetosphere determined from Voyager 1 and 2 plasma wave spectra
Authors: Barnhart B. L. , Kurth W. S. , Groene J. B. , Faden J. B. , Santolik O. , Gurnett D. A.
Published: May 2009

This paper presents an electron plasma density data set for Jupiter's outer magnetosphere derived from high‐resolution wideband measurements of low‐frequency radio and plasma waves obtained by Voyagers 1 and 2 during their 1979 flybys. This work utilizes a new data processing tool that makes important improvements in the identification of the plasma frequency and other characteristic frequencies of the plasma, thereby allowing for the determination of the electron density within the Jovian magnetosphere. Furthermore, this work includes the interpretation of complex spectra including sometimes overlapping wave phenomena including continuum radiation, Z mode emissions, and whistler mode waves. Using the theory of cold plasmas and measurements of the magnetic field from which the electron cyclotron frequency can be calculated, we establish an extensive set of reasoning for interpreting cutoffs and resonances in the wave spectra to identify characteristic frequencies of the plasma, including the electron plasma frequency, R = 0 cutoff, L = 0 cutoff, and upper hybrid resonance frequency. While most Voyager plasma wave data used are obtained in the plasma sheet where the plasma frequency is greater than the cyclotron frequency, this investigation also analyzes observations in the lobe where the cyclotron frequency is greater than the plasma frequency to interpret the various cutoffs and resonances in the spectrum. The resulting data set for the electron densities has higher temporal resolution than any others that exist today. Also, given the identification of spectral features to accuracies of ∼100 Hz or better, the density measurements are among the most accurate for Jupiter's magnetosphere.
First Hematological Signals of Latent Anemia to Aging Population
Authors: Udristioiu Aurelian
Published: May 2009

Anemia is an independent risk factor for morbidity and mortality in an array of disorders common to seniors including cancer, renal diseases and heart diseases. The aim of this study was to identify the first hematological signals of latent anemia to aging population using as screening the hematological aspects of cells from peripheral blood and additional tests, establishing the etiology of anemia in the elderly.Method: Additional to level of hemoglobin(HGB) and hematocrit (HCT) have been included Hematological Indexes( MCV, HCV, MCHC ), red cell distribution width,(RDW), reticulocyte count (RET), serum iron (SI), total iron binding capacity,(TIBC), transferrin saturation index, (TSI), serum ferritin( SF), on an study of 140 adult hospitalized patients, in wars with chronic diseases males and females with ages past 65 years.

Results:

Anemia of chronic diseases (ACD) is more common in the elderly than other group.In ACD correlation of hematological testes was following: 32 % with normal HGB, HCT and normal hematological indexes, 21.5 % with only MCV or HCV decreased, 22.5 % patients with HB in value 10.8 g/dl for women and 11.08 g/dl form men, 15 % patients with HB 9.8-10.6g/d L and 9% patients with HB 7.8-9.6, g/d L (mean SD=2,2 ); average number of Reticulocytes =1.2%; Corrected Index Ret = 0.6%; Production Index Reticulocytes, (PIR) = 1.4, meaning the hypo-regenerative anemia with globular value, GV =1.2. Precision: CV < 2% for RBC, CV < 1% for HB and CV < 2% for HCT. Accuracy: R > 0.95 for RBC, HGB and HCT. In this study was observed a higher prevalence of anemia in elderly men than in women. Anemia of renal disease is considered to be a distinct form of anemia and is typical due to decreased EPO production in 20 percent from normal value to adult persons. Discussion: Elderly anemic patients fail to show increases in erythrocytes progenitors and reticuloculocytes as a result of chronic stress along life. In some cases, the presence of anemia may reflect an underling or undetected medical condition.

Conclusions:

Most anemic adults are asymptomatic until HGB fall below normal values. For this reason a routine anemia screening should be recommended by HB, HCT and MCV, HCV, MCHC to persons with age past >_65 year.
Effect of weight loss on HDL-apoA-II kinetics in the metabolic syndrome
Authors: Ng Theodore W. K. , Chan Dick C. , Barrett P. Hugh R. , Watts Gerald F.
Published: May 2009

Reduced HDL (high-density lipoprotein) concentration in the MetS (metabolic syndrome) is associated with increased risk of cardiovascular disease and is related to defects in HDL-apoA-II (apolipoprotein A-II) kinetics. Dietary restriction is the most commonly used weight loss strategy. In the present study, we examined the effect of weight loss on HDL-apoA-II kinetics in men with the MetS at the start and end of a 16-week intervention trial of a hypocaloric low-fat diet (n=20) compared with a weight maintenance diet (n=15), using a stable isotope technique and compartmental modelling. The low-fat diet achieved a significant reduction (P<0.01) in BMI (body mass index), abdominal fat compartments and HOMA (homoeostasis model assessment) score compared with weight maintenance. Weight loss also significantly (P<0.05) decreased both the production rate (−23%) and FCR (fractional catabolic rate) (−12%) of HDL-apoA-II, accounting for a net decrease in apoA-II concentration (−9%). Reductions in the HDL-apoA-II production rate were significantly associated with changes in body weight (r=0.683, P<0.01), plasma triacylglycerols (triglycerides) (r=0.607, P<0.01) and, to a lesser extent, plasma insulin (r=0.440, P=0.059) and HOMA-IR (HOMA of insulin resistance) (r=0.425, P=0.069). Changes in the apoA-II FCR were also significantly associated with reductions in visceral adipose tissue mass (r=0.561, P=0.010). In conclusion, in obese men with the MetS, short-term weight loss with a low-fat low-caloric diet lowers plasma apoA-II concentrations by decreasing both the production and catabolism of HDL-apoA-II. The cardiometabolic significance of this effect on HDL metabolism remains to be investigated further.
A paradigm shift from stationary stability to dynamically evolving stability required from experimental fusion plasmas
Authors: Kondoh Yoshiomi
Published: May 2009

A paradigm shift from the traditional concept of stationary stability to the new one of dynamically evolving stability is proposed in order to correctly deal with dynamically evolving experimental plasmas. A new process to derive generalized simultaneous eigenvalue equations is presented by the use of a generalized theory of self-organization. The final simultaneous eigenvalue equations are shown to be a good candidate for the proposed paradigm shift because their mathematical forms exactly describe the self-similarly evolving and dynamically stable states available to various dynamic systems. Typical numerical configurations of mutually dependent, dynamically stable, and self-similarly evolving physical quantities are presented for the reversed-field pinch plasmas in cylindrical geometry by solving a set of simultaneous eigenvalue equations for the two-fluid model. A new algorithm is presented to find the dynamically stable, self-similarly evolving and self-organized configurations and to investigate quantitatively the robust dynamical stability of these configurations.
Theoretical study on the mechanism of abnormal dielectric susceptibility behaviors of ferroelectric bilayer films
Authors: Cui Lian , Lü Tianquan , Xu Xu , Zhou Jing
Published: May 2009

Based on the modified Ginzburg–Landau–Devonshire phenomenological theory, a ferroelectric bilayer film with the transition layer within each constituent film and an interfacial coupling between two materials has been studied. The dielectric susceptibility of a bilayer film composed of two equally thick ferroelectric constituent films is discussed. The results show that there is a transition point, which is an equilibrium point of two contrary actions of the transition layer and interfacial coupling. The anomalous dielectric susceptibility behaviors of a ferroelectric bilayer film are ascribed to the competition of the transition layer and interfacial coupling deviated from this transition point.
Exchange-compelled vortices on magnetic core-shell cylinders and their spin-transfer torque driven dynamics
Authors: Xing Xiangjun , Yu Yunpeng , Li Shuwei
Published: May 2009

Magnetic core-shell cylinders comprising a hard dot and a soft ring are proposed. Due to energy redistribution, a compelled vortex is formed on the central dot. Current-driven vortex dynamics is clarified. Because of the confinement effect, the vortex-core gyrotropic motion, and further the vortex-antivortex pair mediated reversal are suppressed. Instead, the vortex-core reversal is achieved through a traveling Bloch-point mediated process. Depending on the current density, the Bloch-point-mediated reversal process adopts different modes (A-, B-, and C-modes). The switching time is a nonmonotonic function of the current density. For the 80-nm-wide cylinder, the A-mode gives a “clean” vortex-core reversal.
Driving toroidally asymmetric current through the tokamak scrape-off layer. II. Magnetic field structure and spectrum
Authors: Joseph Ilon
Published: May 2009

The structure of the magnetic field perturbations due to nonaxisymmetric field-aligned currents in the tokamak scrape-off layer (SOL) are analytically calculated near the X-point. Paper I [I. Joseph et al., Phys. Plasmas 16, 052510 (2009)] demonstrated that biasing divertor target plates in a toroidally asymmetric fashion can generate an appreciable toroidally asymmetric parallel current density in the SOL along the separatrix. Here, the magnetic field perturbation caused by a SOL current channel of finite width and stepwise constant amplitude at the target plate is derived. Flux expansion amplifies the magnetic perturbation near the X-point, while phase interference causes the SOL amplitude to be reduced at large toroidal mode number. Far enough from the current channel, the magnetic field can be approximated as arising from a surface current near the separatrix with differing amplitudes in the SOL and the divertor leg. The perturbation spectrum and resonant components of this field are computed analytically asymptotically close to the separatrix in magnetic flux coordinates. The size of the stochastic layer due to the applied perturbation that would result without self-consistent plasma shielding is also estimated. If enough resonant field is generated, control of the edge pressure gradient may allow stabilization of edge localized modes.
Quasisteady and steady states in global gyrokinetic particle-in-cell simulations
Authors: Jolliet S. , McMillan B. F. , Vernay T. , Villard L. , Bottino A. , Angelino P.
Published: May 2009

Collisionless delta-f gyrokinetic particle-in-cell simulations suffer from the entropy paradox, in which the entropy grows linearly in time while low-order moments are saturated. As a consequence, these simulations do not reach a steady state and are unsuited to make quantitative predictions. A solution to this issue is the introduction of artificial dissipation. The notion of steady state in gyrokinetic simulations is studied by deriving an evolution equation for the fluctuation entropy and applying it to the global collisionless particle-in-cell code ORB5 [S. Jolliet et al., Comput. Phys. Commun. 177, 409 (2007)]. It is shown that a recently implemented noise-control algorithm [B. F. McMillan et al., Phys. Plasmas 15, 052308 (2008)] based on a W-stat provides the necessary dissipation to reach a steady state. The two interesting situations of decaying and driven turbulence are considered. In addition, it is shown that a separate heating algorithm, not based on a W-stat, does not lead to a statistical steady state.
The Institutions of ‘Strong’ Local Political Leadership in Spain
Authors: Sweeting David
Published: May 2009

In this paper I examine local political leadership in Spain. Spanish mayors are examples of ‘strong mayors’—that is, they have considerable executive authority and discretion in municipal affairs. Yet little detailed research exists on the formal and informal institutional bases of their position. I fill this gap by presenting empirical research on two Spanish municipalities. Using a new institutionalist theoretical perspective, I examine the rules around the appointment and removal of the mayor, the composition of the cabinet, the role of the full council, and the conventions around the role of the mayor in the municipality. Legal powers, a culture of individualised leadership, and councillor representation based on support for the party are all important for maintaining the mayor's position. Some formal rules around the mayor in the case-study municipalities are ‘latent’—that is, they exist but are not used.
The characteristics of the internal transport barrier under reactor relevant conditions in JT-60U weak shear plasmas
Authors: Takenaga H. , Oyama N. , Urano H. , Sakamoto Y. , Asakura N. , Kamiya K. , Miyo Y. , Nishiyama T. , Sasajima T. , Masaki K. , Kaminaga A. , Ichige H. , Bucalossi J. , Marty V. , Ide S. , Koide Y. , Kamada Y.
Published: June 2009

The characteristics of the internal transport barrier (ITB) have been investigated under reactor relevant conditions with edge fuelling and electron heating in JT-60U weak shear plasmas. In order to investigate the effects of edge fuelling and electron heating separately, two independent classes of experiments were performed, i.e. one with edge fuelling and ion dominant heating and the other with central beam fuelling and additional electron heating. High confinement was sustained at high density with edge fuelling by shallow pellet injection or supersonic molecular beam injection. The ion temperature (T
i) in the central region inside the ITB decreased due to cold pulse propagation even with edge fuelling. By optimizing the injection frequency and the penetration depth, the decreased central T
i recovered and a good ITB was sustained with enhanced pedestal pressure. The T
i-ITB also degraded significantly with electron cyclotron heating (ECH), when the stiffness feature was strong in the electron temperature (T
e) profile. The ion thermal diffusivity in the ITB region increased with the electron thermal diffusivity, indicating the existence of a clear relation between ion and electron thermal transport. On the other hand, the T
i-ITB remained unchanged or even grew, when the stiffness feature was weak in the T
e profile. The density fluctuation level at the ITB seemed unchanged during ECH; however, the correlation length became longer in the T
i-ITB degradation case and shorter in the T
i-ITB unchanging case.
Bootstrap current calculations with the SPBSC and the VENUS+δf codes for the Large Helical Device
Authors: Isaev M. Yu. , Watanabe K. Y. , Cooper W. A. , Yokoyama M. , Yamada H. , Sauter O. , Tran T. M. , Bergmann A. , Beidler C. D. , Maaßberg H.
Published: June 2009

Total bootstrap current calculations with the updated VENUS+δf code that incorporates energy convolution and the momentum correction technique have been performed for the reference tokamak JT-60U cases and for the experimental Large Helical Device (LHD, NIFS, Japan) configurations with different magnetic axis positions. The VENUS+δf results have been compared with the corresponding tokamak results of the neoclassical bootstrap current models for the general axisymmetric equilibria and arbitrary collisionality regime, as well as with the corresponding 3D SPBSC code numerical predictions and with the LHD experimental tendency.
rtracklayer: an R package for interfacing with genome browsers
Authors: Lawrence Michael , Gentleman Robert , Carey Vincent
Published: May 2009

Summary: The rtracklayer package supports the integration of existing genome browsers with experimental data analyses performed in R. The user may (i) transfer annotation tracks to and from a genome browser and (ii) create and manipulate browser views to focus on a particular set of annotations in a specific genomic region. Currently, the UCSC genome browser is supported.

Availability: The package is freely available from http://www.bioconductor.org/. A quick-start vignette is included with the package.

Contact:  mflawren@fhcrc.org
Evidence for the presence of two distinct membrane ATPases in Spiroplasma citri
Authors: Simoneau Philippe , Labarère* Jacques
Published: June 2009

Triton X-100 (TX-100) extraction of Spiroplasma citri plasma membrane solubilized two types of ATPase differing in their pH of maximum activity. The activity measured at pH 8·5 was inhibited by vanadate and the activity measured at pH 6·5 was not. The vanadate-sensitive ATPase had a relatively basic isoelectric point (8·65) and therefore could be separated from the vanadate-insensitive ATPase using chromatofocusing. Elution of the TX-100 membrane extract in a pH gradient from 9 to 6 generated two peaks of ATPase activity: one in the acidic range, composed of an F0F1-type ATPase, and one in the basic range, corresponding to the vanadate-sensitive activity. Electrophoretic analysis of proteins from the latter peak revealed one major polypeptide of 37 kDa. This peptide was shown to correspond to spot A37 in a two-dimensional protein map of S. citri. Using the gene for the kdp-operon of Escherichia coli as a probe in heterologous hybridization, sequences were detected in the genomic DNA of S. citri, suggesting that a gene coding for an enzyme related to this P-type ATPase is present in the S. citri genome. We therefore postulate the presense of two distinct kinds of ATPase in S. citri: one of the F-type which is resistant to vanadate inhibition, and one, probably of the P-type, which is vanadate-sensitive.
Regulation of S-adenosylmethionine decarboxylase during the germination of sporangiospores of Mucor rouxii
Authors: Calvo-Mendez Carlos , Ruiz-Herrerax Jose
Published: June 2009

General properties of S-adenosylmethionine decarboxylase (SAMDC) from Mucor rouxii were studied. Dormant spores of the fungus did not contain detectable levels of the enzyme, but it started to be synthesized at early stages of spore germination. Kinetics of synthesis changed before emergence of the germ tube, with a corresponding increase in a second SAMDC activity which, in contrast to the one originally synthesized, was not activated by putrescine. Development of the second enzyme activity required de novo protein synthesis. Neither enzymic activity was stimulated by Mg2+. Addition of the SAMDC inhibitor methylglyoxal bis-(guanylhydrazone) (MGBG) stopped fungal development in growth phase Ia: cells became spherical and showed ultrastructural alterations. Although MGBG inhibited polyamine formation, it barely inhibited protein and RNA biosynthesis during the first hour of incubation. However, at later periods, biosynthesis of both macromolecules was strongly decreased. When MGBG was added to growth media 3 h after inoculation of spores, it did not affect spore germination and outgrowth. A hypothesis for two different roles of spermidine and putrescine in spore germination is discussed.
Bacterial production of trans-dihydroxycyclohexadiene carboxylates by metabolic pathway engineering
Authors: Müller Rolf , Breuer Michael , Wagener Andreas , Schmidt Karsten , Leistner Eckhard
Published: June 2009

Homochiral-cis-cyclohexa-3,5-diene-1,2-diols are important synthons. We found a way to produce trans-configured homochiral diols using recombinant Klebsiella pneumoniae 62-1. Transformation of this mutant (Phe- Trp- Tyr-) with plasmids carrying genes involved in chorismic and isochorismic acid metabolism leads to the production of either (+)-trans-(2S,3S)-2,3-dihydroxycyclohexa-4,6-dienecarboxylic acid or (-)-trans-(3R,4R)-3,4-dihydroxycyclohexa-1,5-dienecarboxylic acid, with a yield of 70 or 90 mg (l culture broth)−1, respectively. The metabolic shift from one diene to the other is caused by a change in activity of isochorismate hydroxymutase and/or isochorismatase which in turn results from growth under iron deficiency or overexpression of genes (entC and/or entB) involved in chorismate metabolism.
Quantitative Assessment of in Planta Distribution of Metabolic Activity and Gene Expression of an Endophytic Fungus
Authors: Herd Scott , Christensen Michael J. , Saunders Karyn , Scott D. Barry , Schmid Jan
Published: June 2009

Using perennial ryegrass infected with an Acremonium transformant carrying the Escherichia coli β-D-glucuronidase gene (gusA) (GUS system) under control of a constitutive promoter, we have developed methods for the quantitative extraction of endophyte-associated GUS activity from plant material. Fluorometric assays of these extracts allow quantitative assessment of the distribution of endophyte-associated GUS activity within single plants (tillers) with high resolution. Fluorescence microscopy with the dye Imagene Green can in addition visualize individual GUS-expressing hyphae. Since the transformant expresses the GUS gene constitutively, GUS activity can be used as an indicator of in planta endophyte metabolic activity. Using this approach we found that (i) the concentration of endophyte metabolic activity in plant tissue decreases with increasing plant size, (ii) approximately 70% of endophyte metabolic activity present in a plant is located in the leaf sheaths, (iii) basal-apical gradients and lateral (younger to older tissue) gradients of endophyte metabolic activity exist and (iv) basal-apical gradients are established early in leaf development. Our data suggest that the concentration of endophyte in each part of the plant is regulated so that a predetermined threshold of total endophyte activity per plant is not exceeded and a consistent distribution pattern is maintained.
Growth-phase-dependent transcriptional regulation of the pcm and surE genes required for stationary-phase survival of Escherichia coli
Authors: Li Chuan , Wu Pei-Ying , Hsieh Mingli
Published: June 2009

Two neighbouring genes, surE and pcm, at 59 min on the Escherichia coli chromosome are both required for stationary-phase survival. Operon fusions of the putative promoter regions in front of surE (P2) or pcm (P3) with the lacZ reporter gene were constructed to study the transcriptional regulation of pcm and surE. Both promoter regions were able to activate -galactosidase activity in a growth-phase-dependent way in either rich or minimal medium. Induction from both promoters reached the highest level in late stationary phase and was independent of the rpoS/katF gene. Spent medium from early as well as late stationary-phase cultures could induce the expression of either promoter even after dialysis or boiling. A high cell density could induce the promoters more rapidly but not to a greater extent. It is proposed that the induction might be correlated with the decline in growth rate of the cells. The induction patterns of either P2 or P3 were very similar, pcm can thus be transcribed from both the P2 and P3 promoters that are regulated in similar ways.
Re-evaluation of the hypothesis that biodegradable surfactants stimulate surface attachment of competent bacteria
Authors: Owen Sarah A. , Russell Nicholas J. , House W. Alan , White Graham F.
Published: June 2009

The hypothesis that biodegradable surfactants stimulate the attachment of biodegradation-competent bacteria to surfaces has been re-evaluated using a variant of the surfactant-degrading bacteriumPseudomonassp. DES1 designatedPseudomonassp. DES2. This variant was identical to the parental strain in terms of its carbon-utilization patterns and alcohol dehydrogenase and alkylsulfatase complements (enzymes involved in surfactant biodegradation), but differed markedly in its growth characteristics when using sodium dodecyl triethoxysulfate or triethylene glycol dodecyl ether as secondary carbon sources.Pseudomonassp. DES1 exhibited diauxie in these surfactant-based culture media in contrast toPseudomonassp. DES2, which exhibited single-phase growth.Pseudomonassp. DES2 did not attach to river sediment in a microcosm system when challenged with a dose of either surfactant, although it did biodegrade the substrate. In contrast,Pseudomonassp. DES1 attached to the river sediment whilst biodegrading the test substrate. It is concluded that the ether-scission system, which is responsible for primary biodegradation of both substrates, is deregulated inPseudomonassp. DES2 in contrast to that inPseudomonassp. DES1, and that, contrary to a previous hypothesis, biodegradable surfactants do not necessarily stimulate the attachment of biodegradation-competent bacteria during their biodegradation.
Influence of Na+ and anions on the dimorphic transition of Candida albicans
Authors: Northrop Frederick D. , Ljubojevic Srdjan , Davies Julia M.
Published: June 2009

The effect of Na+ (CI- or gluconate salt) on growth and dimorphic potential of the pathogenic yeast Candida albicans has been examined. Profiles of germ tube formation as a function of salt addition, pH and temperature indicated Na+ inhibition of germ tube outgrowth at high ambient pH (pH 8.0) which was exacerbated by replacement of CI- with gluconate (as an impermeant analogue). At acidic pH (pH 5.5) and permissive temperature (37 °), gluconate alone promoted the dimorphic transition. Rates of glucose-induced medium acidification and plasma membrane H+-ATPase activity have been measured to assess whether salt treatments could retard the cytoplasmic alkalinization known to precede germ tube formation. The precise site of Na+ action remains unclear but the anion effects may be interpreted in terms of anion-exchanger and channel activity acting to modulate cytosolic pH.
Metabolism of sulfoacetate by environmental Aureobacterium sp. and Comamonas acidovorans isolates
Authors: King Janice E. , Quinn John P.
Published: June 2009

Newly isolated environmental strains of Comamonas acidovorans and Aureobacterium sp. were found to mineralize sulfoacetate at concentrations up to at least 50 mM. Transient sulfite release was detected during growth on sulfoacetate, with essentially quantitative accumulation of sulfate. Cell-free conversion of sulfoacetate could not be obtained, but resting-cell studies indicated that cleavage of the C-S bonds of both sulfoacetate and sulfoacetaldehyde was induced only when sulfoacetate was the sole carbon and energy source. A sulfite-oxidizing activity was also induced under these conditions. Sulfoacetaldehyde sulfo-lyase activity was demonstrated by in vitro assay and by gel zymography in extracts of cells grown on sulfoacetate as sole carbon source. This activity was not present in acetate-grown cells, or in cells grown on sulfoacetate as sole sulfur source. Results suggest that sulfoacetate mineralization in both isolates may proceed by a novel pathway which involves an initial reduction to sulfoacetaldehyde and subsequent cleavage of the C-S bond to yield sulfite and acetate. The proposed pathway may be of environmental significance in the mineralization of plant sulfolipid.
3-Phosphoglycerate kinase: a glycolytic enzyme protein present in the cell wall of Candida albicans
Authors: Alloush Habib M. , López-Ribot José L. , Masten Barbara J. , Chaffin W. LaJean
Published: June 2009

We have used a polyclonal antiserum to cell wall proteins of Candida albicans to isolate several clones from a cDNA λgt11 expression library. Affinity-purified antibody prepared to the fusion protein of one clone identified a 40 kDa moiety present in cell wall extracts from both morphologies of the organism. Indirect immunofluorescence demonstrated expression of this moiety at the C. albicans cell surface. Sequencing of a pBluescript II genomic clone identified with the cDNA clone revealed an open reading frame for a 417 amino acid protein. The nucleotide sequence showed significant homology with 3-phosphoglycerate kinase (PGK) genes, with 88%, 77% and 76% nucleotide homology with the PGK genes from Candida maltosa, Saccharomyces cerevisiae and Kluyveromyces lactis, respectively. The deduced amino acid sequence was consistent with this identification of the sequence as PGK1 of C. albicans. This finding was confirmed by a positive immunological response of a commercially available purified PGK from S. cerevisiae with the affinity-purified antibody against the fusion protein of the cDNA clone. The presence of PGK in the cell wall was confirmed by two additional methods. Cell wall proteins were biotinylated with a derivative that does not permeate the cell membrane to distinguish extracellular from cytosolic proteins. Biotinylated PGK was detected among the biotinylated proteins obtained following streptavidin affinity chromatography. Immunoelectron microscopy revealed that the protein was present at the outer surface of the cell membrane and cell wall as well as expected in the cytoplasm. Northern blot analysis revealed that the gene transcript was present in C albicans cells growing under different conditions, including different media, temperatures and morphologies. Most of the enzyme activity was found in the cytosol. Low enzymic activity was detected in intact cells but not in culture filtrates. These observations confirmed that PGK is a bona fide cell wall protein of C. albicans.
A DNA-binding protein from Candida albicans that binds to the RPG box of Saccharomyces cerevisiae and the telomeric repeat sequence of C. albicans
Authors: Ishii Nobuya , Yamamoto Mutumi , Lahm Hans-Werner , Lizumi Shinnji , Yoshihara Fumie , Nakayama Hironobu , Arisawa Mikio , Aoki Yuhko
Published: June 2009

Electromobility shift assays with a DNA probe containing the Saccharomyces cerevisiae ENO1 RPG box identified a specific DNA-binding protein in total protein extracts of Candida albicans. The protein, named Rbf1p (RPG-box-binding protein 1), bound to other S. cerevisiae RPG boxes, although the nucleotide recognition profile was not completely the same as that of S. cerevisiae Rap1p (repressor-activator protein 1), an RPG-box-binding protein. The repetitive sequence of the C. albicans chromosomal telomere also competed with RPG-box binding to Rbf1p. For further analysis, we purified Rbf1p 57600-fold from C. albicans total protein extracts, raised mAbs against the purified protein and immunologically cloned the gene, whose ORF specified a protein of 527 aa. The bacterially expressed protein showed RPG-box-binding activity with the same profile as that of the purified one. The Rbf1p, containing two glutamine-rich regions that are found in many transcription factors, showed transcriptional activation capability in S. cerevisiae and was predominantly observed in nuclei. These results suggest that Rbf1p is a transcription factor with telomere-binding activity in C. albicans.
Fire blight protection with avirulent mutants of Erwinia amylovora
Authors: Tharaud Michel , Laurent Jacqueline , Faize Mohamed , Paulin Jean-Pierre
Published: June 2009

Fire blight is a necrotic disease caused by the bacterium Erwinia amyiovora, which affects pears, apples and ornamentals including Crataegus, Pyracantha, and Cotoneaster. The disease can be only partially controlled, through the use of resistant genotypes, cultural measures and antibacterial compounds, thus other methods must be investigated. It has long been established that avirulent isolates of the pathogen can control the disease, under experimental conditions. However, field use of avirulent isolates is not acceptable because of their unknown genetic stability. The protective ability under controlled conditions of genetically characterized avirulent insertion mutants of E. amylovora was examined. A bioassay on apple seedlings was used for the determination of the protective ability of 34 insertion mutants (hrp, dsp, ams). Some protective effect could be observed with most of the mutants tested and was dependent on the avirulent/virulent inoculum ratio as well as on the level of virulence of the pathogen; a minimal concentration of the avirulent mutant was necessary to give a significant level of protection. An early competition between avirulent and virulent strains for putative infection sites might be involved. For six of the mutants tested, the protective ability was particularly high and might be related to the alteration of regulatory functions of hrp genes. Results obtained with Ams- and Ams- Hrp- mutants suggested that the bacterial exopolysaccharide might play a role in the protection.
Use of an excision reporter plasmid to study the intracellular mobility of the conjugative transposon Tn916 in Gram-positive bacteria
Authors: Celli Jean , Poyart Claire , Trieu-Cuot Patrick
Published: June 2009

An excision reporter plasmid was constructed to characterize the intracellular mobility of Tn916 in various Gram-positive bacteria. The reporter component of this plasmid is a chloramphenicol-resistance gene which has been insertionally inactivated with the integrative vector pAT112 containing the attachment site of Tn916. Tn916-mediated excision of pAT112, to produce clones resistant to chloramphenicol, was detected in Enterococcus faecalis BM4110, Listeria monocytogenes L028-Str and Streptococcus gordonii BM120, but not in Lactococcus lactis MG1363-RF or in Streptococcus pneumoniae BM124, and always depended upon the ability of the bacterial host to generate circular forms of the transposon. The results suggest that (i) the excision event, although required, is not sufficient for conjugal transfer to occur and (ii) there is no linear relationship between the donor potential of E. faecalis strains and either the excision frequency of pAT112 or the copy number of Tn916 circular intermediates per cell in these hosts. Excision of pAT112 occurred mainly during the late exponential phase of growth of E. faecalis and L. monocytogenes and this recombination event was not stimulated by heat shock, salt and alcohol stresses or by the presence of tetracycline in the medium.
Antigenic polymorphism of the lipopolysaccharides from human and animal isolates of Bordetella bronchiseptica
Authors: Blay Karine Le , Gueirard Pascale , Guiso Nicole , Chaby Richard
Published: June 2009

Six monoclonal antibodies (mAbs) against lipopolysaccharides (LPS) from Bordetella pertussis (P1P3, 60.5), B. parapertussis (PP2, PP6, PP8) and B. bronchiseptica (BRg1) were used to examine the presence of antigenic determinants of LPS on B. bronchiseptica cells. Forty-eight clinical isolates of this Gram-negative bacterium (4 canine, 3 equine, 6 porcine, 4 rabbit and 31 human) were examined. Significant cross-reactivities with the heterologous anti-pertussis and anti-parapertussis mAbs were observed. The isolates also exhibited marked antigenic polymorphism. The 48 isolates could be classified in six immunogroups. Purified LPS preparations extracted from some isolates were analysed by ELISA, thin-layer chromatography, and tricine-SDS-PAGE. The results show that four main types of antigenic polymorphism of B. bronchiseptica LPSs exist: (a) heterogeneity of the core, (b) presence or absence of O-chains, (c) differences in the hinge region between O-chain and core, and (d) differences in interactions of LPS with other cell-surface constituents. Smooth-type LPS molecules, detectable with mAb PP6, were more frequently observed in animal isolates (94%) than in human isolates (52%). Reverse frequencies were found with mAb 60.5 (48% of human isolates, 18% of animal isolates), which is unable to react with long-chain LPSs. This observation could be due to the general absence of some lectin-like receptor, specific to the O-chain, on human bronchoalveolar tissues.
The Clostridium perfringens enterotoxin gene is on a transposable element in type A human food poisoning strains
Authors: Brynestad Sigrid , Synstad Bjørnar , Granum Per Einar
Published: June 2009

Summary: The Clostridium perfringens enterotoxin gene (cpe) is rarely found in naturally isolated strains. In human food poisoning strains, cpe is found on the chromosome, and is located episomally in animal isolates. Observations that the gene was somewhat unstable and could be gained or lost suggested that the gene was on a mobile element. An IS200-like element, IS1469, is almost always upstream of cpe. A new insertion element was identified, IS1470, a member of the IS30 family, which is found both up- and downstream of cpe in the type A strain NCTC 8239. PCR results confirmed that this configuration was conserved in type A human food poisoning strains. The enterotoxin gene was on a 6.3 kb transposon which, in addition to the two flanking copies of IS1470, included IS1469 and two 1 kb stretches, one on each side of cpe, with no open reading frames. Results indicated that 14 bp was copied from the genome during insertion. Details of the configuration of DNA in this transposon are presented, and the possible connection of this transposon with the movement of the enterotoxin gene is discussed.