bluuebunny/crossref_metadata_2025_split huggingface dataset:
HspR is a global negative regulator of heat shock gene expression in Deinococcus radiodurans
Authors: Schmid Amy K. , Howell Heather A. , Battista John R. , Peterson Scott N. , Lidstrom Mary E. 
Published: February 2005

SummaryThe HspR protein functions as a negative regulator of chaperone and protease gene expression in a diversity of bacteria. Here we have identified, cloned and deleted the Deinococcus radiodurans HspR homologue, DR0934. ΔhspR mutants exhibit moderate growth defects when shifted to mild heat shock temperatures, but are severely impaired for survival at 48°C. Using quantitative reverse transcription polymerase chain reaction and global transcriptional analysis, we have identified 14 genes that are derepressed in the absence of stress in the ΔhspR background, 11 of which encode predicted chaperones and proteases, including dnaKJgrpE, ftsH, lonB, hsp20 and clpB. Promoter mapping indicated that the transcription of these genes initiates from a promoter bearing a σ70‐type consensus, and that putative HspR binding sites (HAIR) were present in the 5′‐untranslated regions. Electrophoretic mobility shift assays indicated that HspR binds to these promoters at the HAIR site in vitro. These results strongly suggest that DR0934 encodes the HspR‐like global negative regulator of D. radiodurans that directly represses chaperone and protease gene expression by binding to the HAIR site in close proximity to promoter regions.
Changes in lipopolysaccharide structure induce the σE‐dependent response of Escherichia coli
Authors: Tam Christina , Missiakas Dominique 
Published: February 2005

SummaryThe envelope of Escherichia coli is composed of an asymmetric lipid bilayer containing lipopolysaccharide, phospholipid and outer membrane proteins (OMPs). Physical and chemical stresses impact on the integrity of the outer membrane envelope and trigger the σE‐dependent response, whereby E. coli activates the expression of genes that increase its capacity for folding OMPs and synthesizing lipopolysaccharide (LPS). While it has already been appreciated that misfolded OMPs induce the σE response, a role for LPS in activating this pathway was hitherto unknown. Here we show that ammonium metavandate (NH4VO3) induces multiple changes in E. coli LPS structure and activates the σE‐dependent response without altering OMP. One such NH4VO3‐mediated LPS decoration, the CrcA/PagP‐catalysed addition of palmitate to lipid A, appeared to be alone sufficient to activate transcription at σE‐dependent promoters. Furthermore, reduced acylation of LPS, caused by htrB or msbB mutations, also resulted in a constitutive expression of the σE regulon above wild‐type levels. Production of these aberrant outer membrane lipids did not noticeably affect the composition or the amount of OMPs. A model is proposed whereby structural intermediates of the LPS biosynthetic pathway or modified LPS molecules may function as signals that activate the σE response.
LmxMPK9, a mitogen‐activated protein kinase homologue affects flagellar length in Leishmania mexicana
Authors: Bengs Florian , Scholz Anne , Kuhn Daniela , Wiese Martin 
Published: February 2005

SummaryComponents of mitogen‐activated signal transduction pathways have been shown to be involved in flagellum biogenesis and maintenance. A mitogen‐activated protein kinase homologue, designated LmxMPK9 from Leishmania mexicana, has been recently identified in a homology screen and its mRNA found to be present in all life stages. Three different splice‐addition sites were used for mRNA maturation in trans‐splicing in the different life stages. However, here we show that LmxMPK9 protein is exclusively found in the promastigote stage. Recombinant expression of LmxMPK9 in Escherichia coli and kinase assays revealed a temperature optimum at 27°C, the optimal growth temperature for L. mexicana promastigotes, and a preference for manganese to promote substrate phosphorylation of myelin basic protein. A deletion mutant for the single‐copy gene revealed significantly elongated flagella, whereas overexpression led to a subpopulation with rather short to no flagella suggesting a role for LmxMPK9 in flagellar morphogenesis.
Net primary production and light use efficiency in a mixed coniferous forest in Sweden
Authors: LAGERGREN FREDERIK , EKLUNDH LARS , GRELLE ACHIM , LUNDBLAD MATTIAS , MÖLDER MEELIS , LANKREIJER HARRY , LINDROTH ANDERS 
Published: February 2005

ABSTRACTSimple light use efficiency (ɛ) models of net primary production (NPP) have recently been given great attention (NPP = ɛ × absorbed photosynthetically active radiation). The underlying relationships have, however, not been much studied on a time step less than a month. In this study daily NPP was estimated as the sum of net ecosystem exchange (NEE) and heterotrophic respiration (Rh) of a mixed pine and spruce forest in Sweden. NEE was measured by eddy correlation technique and Rh was estimated from measurements of forest floor respiration (Rf) and the root share of Rf. The total yearly NPP was on average 810 g C m−2 year−1 for 3 years and yearly ɛ was between 0.58 and 0.71 g C MJ−1, which is high in comparison with other studies. There was a seasonal trend in ɛ with a relatively constant level of approximately 0.90 g C MJ−1 from April to September Daily NPP did not increase for daily intercepted radiation above 6 MJ m−2 d−1, indicating that between‐years variation in NPP is not directly dependent on total Qi. The light was most efficiently used at an average daytime temperature of around 15 °C. At daytime vapour pressure deficit above 1400 Pa ɛ was reduced by approximately 50%.
On the relationship between isoprene emission and thermotolerance in Phragmites australis leaves exposed to high temperatures and during the recovery from a heat stress
Authors: VELIKOVA V. , LORETO F. 
Published: February 2005

ABSTRACTThermotolerance induced by isoprene has been assessed during heat bursts but there is little information on the ability of endogenous isoprene to confer thermotolerance under naturally elevated temperature, on the interaction between isoprene‐induced thermotolerance and light stress, and on the persistence of this protection in leaves recovering at lower temperatures. Moderately high temperature treatment (38 °C for 1.5 h) reduced photosynthesis, stomatal conductance, and photochemical efficiency of photosystem II in isoprene‐emitting, but to a significantly lower extent than in isoprene‐inhibited Phragmites australis leaves. Isoprene inhibition and high temperature independently, as well as together, induced lipid peroxidation, increased level of H2O2, and increased catalase and peroxidase activities. However, leaves in which isoprene emission was previously inhibited developed stronger oxidative stress under high temperature with respect to isoprene‐emitting leaves. The heaviest photosynthetic stress was observed in isoprene‐inhibited leaves exposed to the brightest illumination (1500 µmol m−2 s−1) and, in general, there was also a clear additive effect of light excess on the formation of reactive oxygen species, antioxidant enzymes, and membrane damage. The increased thermotolerance capability of isoprene‐emitting leaves may be due to isoprene ability to stabilize membranes or to scavenge reactive oxygen species. Irrespective of the mechanism by which isoprene reduces thermal stress, isoprene‐emitting leaves are able to quickly recover after the stress. This may be an important feature for plants coping with frequent and transient temperature changes in nature.
Light‐induced transient ion flux responses from maize leaves and their association with leaf growth and photosynthesis
Authors: ŽIVANOVIĆ B. D. , PANG J. , SHABALA S. 
Published: February 2005

ABSTRACTNet fluxes of H+, K+ and Ca2+ ions from maize (Zea mays L.) isolated leaf segments were measured non‐invasively using ion‐selective vibrating microelectrodes (the MIFE technique). Leaf segments were isolated from the blade base, containing actively elongating cells (basal segments), and from non‐growing tip regions (tip segments). Ion fluxes were measured in response to bright white light (2600 µmol m−2 s−1) from either the leaf segments or the underlying mesophyll (after stripping the epidermis). Fluxes measured from the mesophyll showed no significant difference between basal and tip regions. In leaf segments (epidermis attached), light‐induced flux kinetics of all ions measured (H+, Ca2+ and K+) were strikingly different between the two regions. It appears that epidermal K+ fluxes are required to drive leaf expansion growth, whereas in the mesophyll light‐induced K+ flux changes are likely to play a charge balancing role. Light‐stimulated Ca2+ influx was not directly attributable either to leaf photosynthetic performance or to leaf expansion growth. It is concluded that light‐induced ion flux changes are associated with both leaf growth and photosynthesis.
Survival of baboon biotin‐X‐N‐hydroxysuccinimide and 111In‐oxine‐labelled autologous fresh and lyophilized reconstituted platelets
Authors: Valeri C. R. , MacGregor H. , Barnard M. R. , Summaria L. , Michelson A. D. , Ragno G. 
Published: February 2005

Background and Objectives  In accordance with Food and Drug Administration (FDA) regulations, platelets can be stored in the liquid state at 22 °C for only 5 days. Platelets frozen with 6% dimethylsulphoxide (DMSO) can be stored at −80 °C for 2 years, and platelets frozen with 5% DMSO can be stored at −150 °C for 3 years. Studies are being conducted to determine the effects of lyophilization of platelets. In the present study, we assessed the survival of autologous lyophilized‐reconstituted platelets in the baboon.Materials and Methods  We studied fresh baboon platelets and baboon platelets that had been treated with paraformaldehyde, frozen, lyophilized, thawed and reconstituted. Aliquots of these platelets were labelled with 111In‐oxine or biotin‐X‐N‐hydroxysuccinimide (biotin‐X‐NHS) before autotransfusion, and measurements were made of the in vivo recovery and lifespan. We also evaluated the response of fresh and lyophilized platelets to in vitro agonists by measuring the level of platelet surface markers and heterotypic aggregates in the peripheral blood following the autotransfusions.Results  The 111In‐oxine‐ or biotin‐X‐NHS‐labelled lyophilized, reconstituted platelets exhibited survival times of less than 15 min. These platelets did not respond to stimulation with agonists to decrease platelet GPIb and increase platelet P‐selectin and platelet GPIIb‐IIIa levels 1 min post‐transfusion and they accumulated more procoagulant factor V than did the fresh platelets.Conclusions  Lyophilized reconstituted baboon platelets labelled with 111In‐oxine or biotin‐X‐NHS before autotransfusion exhibited an in vivo circulation time of less than 15 min. Further study of the lyophilized, reconstituted platelets is required to evaluate their haemostatic function.
An international collaborative study to replace the 1st international standard for prekallikrein activator
Authors: Longstaff C. , Behr‐Gross M.‐E. , Daas A. , Lackner F. 
Published: February 2005

Background and Objectives  The aim of this study was to replace the 1st International Standard (IS) for prekallikrein activator (PKA) (code 82/530) with a new IS and European Biological Reference Preparation (BRP). The new standards were freeze dried 20% albumin solution containing PKA, the same solution that is tested using these standards. Aspects of the methodology for PKA determination were also examined as part of this study.Materials and Methods  A batch of 20% albumin containing ≈ 30 IU/ml was donated by a manufacturer of blood products and dispensed into ampoules at the National Institute for Biological Standards and Control (NIBSC) to create the candidate IS (02/168, sample B in the study) and at the European Directorate for the Quality of Medicines (EDQM) to create the candidate BRP (sample C in the study). The concentration of PKA in these preparations was determined in an international collaborative study involving 31 laboratories from 17 countries worldwide in comparison with the 1st IS for PKA (82/530) containing 85 IU of PKA per ampoule. Participants were requested to perform their own in‐house method, based on the current Ph. Eur. monograph for determination of PKA in albumin solutions. Participants were provided with sufficient samples to perform two or three assays and were asked to use their local prekallikrein substrate (PKS) and also to use a commercial PKS provided as part of the study, in order to investigate the importance of the source of PKS on the final potency values.Results  Samples B and C emerged with identical PKA concentrations of 29 IU/ml, very close to the expected value. This figure was determined using a variety of statistical methods, with the participants’ own calculated values and values calculated centrally at the EDQM using raw data. The value of 29 IU/ml was consistent and independent of the method of calculation, although interlaboratory variability was more sensitive to the statistical analysis method. There was no statistically significant difference in mean potencies when comparing results with the laboratories’ own local substrate and the substrate provided for the study. All stability studies indicate that these lyophilized preparations of PKA in 20% albumin are extremely stable.Conclusions  Samples B and C were established as the 2nd IS (code 02/168) and PKA activator in albumin BRP batch 1 (Y0000263), respectively, with a potency of 29 IU per ampoule. Results from this study indicate that testing for PKA in albumin may be less sensitive to the source of PKS than previously feared. The study highlights a number of methodological issues that may need revising in the Ph. Eur. general chapter 2.6.15.
Six years’ experience of using the BacT/ALERT system to screen all platelet concentrates, and additional testing of outdated platelet concentrates to estimate the frequency of false‐negative results
Authors: Larsen C. P. , Ezligini F. , Hermansen N. O. , Kjeldsen‐Kragh J. 
Published: February 2005

Background and Objectives  Approximately 1 in every 2000 units of platelets is contaminated with bacteria. The BacT/ALERT automated blood culture system can be used to screen platelet concentrates (PCs) for bacterial contamination.Materials and Methods  Data were collected from May 1998 until May 2004. The number of PCs tested during this period was 36 896, most of which were produced from pools of four buffy‐coats. On the day following blood collection or platelet apheresis, a 5–10 ml sample of the PC was aseptically transferred to a BacT/ALERT culture bottle for detection of aerobic bacteria. The sample was monitored for bacterial growth during the entire storage period of the PC (6·5 days). When a positive signal was generated, the culture bottle, the PC and the erythrocyte concentrates were tested for bacterial growth. In order to determine the frequency of false‐negative BacT/ALERT signals, 1061 outdated PCs were tested during the period from May 2002 to May 2004.Results  Eighty‐eight positive signals were detected by the BacT/ALERT system, of which 12 were interpreted as truly positive. Fourteen signals were interpreted as truly false positive. Thirty‐three signals were interpreted to be probably false positive. Two of 1061 outdated units tested positive, and Bacillus spp. and Staphylococcus epidermidis, respectively, were isolated from these PCs.Conclusions  Between 0·03% and 0·12% of the PCs were contaminated with bacteria. BacT/ALERT is an efficient tool for monitoring PCs for bacterial contamination; however, it is important to realize that false‐negative results may occur.
Laparoscopic pyeloplasty: current status
Authors: Inagaki Takeshi , Rha Koon H. , Ong Albert M. , Kavoussi Louis R. , Jarrett Thomas W. 
Published: February 2005

OBJECTIVETo review current publications and report our results and long‐term follow‐up of laparoscopic transperitoneal pyeloplasty for pelvi‐ureteric junction (PUJ) obstruction.PATIENTS AND METHODSIn all, 147 laparoscopic transperitoneal pyeloplasties were performed between August 1993 and November 2000 (mean patient age 35.7 years, range 10–85). All patients were diagnosed with PUJ obstruction by symptoms and intravenous urography, radionuclide diuretic renography or ultrasonography. An Anderson‐Hynes dismembered pyeloplasty (106), Y‐V plasty (28), Fenger plasty (11) and others (two) were used, according to the intraoperative findings. Twenty‐five patients had secondary obstruction, having had previous surgery to the PUJ. The mean (range) follow‐up was 24 (3–84) months; all patients were followed clinically and radiologically.RESULTSThe mean operative duration time was 246 (100–480) min and estimated blood loss was 158 mL. Crossing vessels were identified in 80 cases. The success rate for all, primary and secondary patients was 95%, 98% and 84%, respectively. With one exception, all failures occurred within 6 months. Twenty‐one patients (22 renal units) had simultaneous laparoscopic pyeloplasty and lithotomy; they were treated successfully and all have an intact PUJ, and 20 renal units (90%) were stone‐free. The overall complication rate was 8.8%.CONCLUSIONSThis series has comparable success rates to those of open pyeloplasty and the morbidity was minimal. Laparoscopic pyeloplasty may soon become the standard operation for PUJ obstruction, especially with crossing vessels.
Metabolite fingerprinting in transgenic lettuce
Authors: Garratt Lee C. , Linforth Robert , Taylor Andrew J. , Lowe Kenneth C. , Power J. Brian , Davey Michael R. 
Published: February 2005

SummaryMetabolite fingerprinting has been achieved using direct atmospheric pressure chemical ionization‐mass spectrometry (APCI‐MS) and linked gas chromatography (GC‐APCI/EI‐MS) for transgenic lettuce (Lactuca sativa L. cv. Evola) plants expressing an IPT gene under the control of the senescence‐specific SAG12 promoter from Arabidopsis thaliana (PSAG12‐IPT). Mature heads of transgenic lettuce and their azygous controls were maintained under defined conditions to assess their shelf life. Transgenic lettuce plants exhibited delayed senescence and significant increases (up to a maximum of threefold) in the concentrations of three volatile organic compounds (VOCs), corresponding to molecular masses of 45, 47 and 63, when compared with heads from azygous plants. These VOCs were identified as acetaldehyde (45), ethanol (47) and dimethyl sulphide (63). The increase in dimethyl sulphide was paralleled by an accumulation of reactive oxygen species (ROS) in the heads of transgenic plants. These results demonstrate the applicability of metabolic fingerprinting techniques to elucidate the underlying pleiotropic responses of plants to transgene expression.
Expression of the maize proteinase inhibitor (mpi) gene in rice plants enhances resistance against the striped stem borer (Chilo suppressalis): effects on larval growth and insect gut proteinases
Authors: Vila Laura , Quilis Jordi , Meynard Donaldo , Breitler Jean Christophe , Marfà Victoria , Murillo Isabel , Vassal Jean Michel , Messeguer Joaquima , Guiderdoni Emmanuel , San Segundo Blanca 
Published: February 2005

SummaryThe maize proteinase inhibitor (mpi) gene was introduced into two elite japonica rice varieties. Both constitutive expression of the mpi gene driven by the maize ubiquitin 1 promoter and wound‐inducible expression of the mpi gene driven by its own promoter resulted in the accumulation of MPI protein in the transgenic plants. No effect on plant phenotype was observed in mpi‐expressing lines. The stability of transgene expression through successive generations of mpi rice lines (up to the T4 generation) and the production of functional MPI protein were confirmed. Expression of the mpi gene in rice enhanced resistance to the striped stem borer (Chilo suppressalis), one of the most important pests of rice. In addition, transgenic mpi plants were evaluated in terms of their effects on the growth of C. suppressalis larvae and the insect digestive proteolytic system. An important dose‐dependent reduction of larval weight of C. suppressalis larvae fed on mpi rice, compared with larvae fed on untransformed rice plants, was observed. Analysis of the digestive proteolytic activity from the gut of C. suppressalis demonstrated that larvae adapted to mpi transgene expression by increasing the complement of digestive proteolytic activity: the serine and cysteine endoproteinases as well as the exopeptidases leucine aminopeptidase and carboxypeptidases A and B. However, the induction of such proteolytic activity did not prevent the deleterious effects of MPI on larval growth. The introduction of the mpi gene into rice plants can thus be considered as a promising strategy to protect rice plants against striped stem borer.
Production of cyanophycin, a suitable source for the biodegradable polymer polyaspartate, in transgenic plants
Authors: Neumann Katrin , Stephan Dirk Paul , Ziegler Karl , Hühns Maja , Broer Inge , Lockau Wolfgang , Pistorius Elfriede K. 
Published: February 2005

SummaryThe production of biodegradable polymers in transgenic plants in order to replace petrochemical compounds is an important challenge for plant biotechnology. Polyaspartate, a biodegradable substitute for polycarboxylates, is the backbone of the cyanobacterial storage material cyanophycin. Cyanophycin, a copolymer of l‐aspartic acid and l‐arginine, is produced via non‐ribosomal polypeptide biosynthesis by the enzyme cyanophycin synthetase. A gene from Thermosynechococcus elongatus BP‐1 encoding cyanophycin synthetase has been expressed constitutively in tobacco and potato. The presence of the transgene‐encoded messenger RNA (mRNA) correlated with changes in leaf morphology and decelerated growth. Such transgenic plants were found to produce up to 1.1% dry weight of a polymer with cyanophycin‐like properties. Aggregated material, able to bind a specific cyanophycin antibody, was detected in the cytoplasm and the nucleus of the transgenic plants.
Optimization of Agrobacterium‐mediated transient assays of gene expression in lettuce, tomato and Arabidopsis
Authors: Wroblewski Tadeusz , Tomczak Anna , Michelmore Richard 
Published: February 2005

Summary Agrobacterium‐mediated transient assays for gene function are increasingly being used as alternatives to genetic complementation and stable transformation. However, such assays are variable and not equally successful in different plant species. We analysed a range of genetic and physiological factors affecting transient expression following agroinfiltration, and developed a protocol for efficient and routine transient assays in several plant species. Lettuce exhibited high levels of transient expression and was at least as easy to work with as Nicotiana benthamiana. Transient expression occurred in the majority of cells within the infiltrated tissue and approached 100% in some regions. High levels of transient expression were obtained in some ecotypes of Arabidopsis; however, Arabidopsis remains recalcitrant to routine, genotype‐independent transient assays. Transient expression levels often exceeded those observed in stably transformed plants. The laboratory Agrobacterium tumefaciens strain C58C1 was the best strain for use in plant species that did not elicit a necrotic response to A. tumefaciens. A wild A. tumefaciens strain, 1D1246, was identified that provided high levels of transient expression in solanaceous plants without background necrosis, enabling routine transient assays in these species.