bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inactivation of a Predicted Leader Peptidase Prevents Photoautotrophic Growth of
Synechocystis
sp. Strain PCC 6803
Authors: Zhbanko Maria , Zinchenko Vladislav , Gutensohn Michael , Schierhorn Angelika , Klösgen Ralf Bernd 
Published: April 2005

ABSTRACT

To establish the role of the two putative type I leader peptidases (LepB1 and LepB2) encoded in the genome of the cyanobacterium
Synechocystis
sp. strain PCC 6803, we generated independent knockout mutants for both genes by introducing kanamycin resistance cassettes into the two open reading frames (sll0716 [
lepB1
] and slr1377 [
lepB2
], respectively). Although the insertion was successful in both instances, it was not possible to select homozygous mutant cells for
lepB2
, suggesting that the function of this gene is essential for cell viability. In contrast, LepB1 is apparently essential only for photoautotrophic growth, because homozygous
lepB1
::Km
r
cells could be propagated under heterotrophic conditions. They were even capable to some extent of photosynthetic oxygen evolution. However, the photosynthetic activity decreased gradually with extended incubation in the light and was particularly affected by high light intensities. Both features were indicative of photooxidative damage, which was probably caused by inefficient replacement of damaged components of the photosynthetic machinery due to the lack of a leader peptidase removing the signal peptides from photosynthetic precursor proteins. Indeed, processing of the PsbO precursor polypeptide to the corresponding mature protein was significantly affected in the mutant, and reduced amounts of other proteins that are synthesized as precursors with signal peptides accumulated in the cells. These results strongly suggest that LepB1 is important for removal of the signal peptides after membrane transport of the components of the photosynthetic machinery, which in turn is a prerequisite for the biogenesis of a functional photosynthetic electron transport chain.
Plasmid-Encoded Regulator of Extracellular Proteases inBacillus anthracis
Authors: Aronson Arthur I. , Bell Chris , Fulroth Ben 
Published: April 2005

ABSTRACTBacillus anthracisSterne cured of the pXO1 plasmid had enhanced secreted protease activity during the postexponential phase but no change in hemolytic or lecithinase activities. A zymogen profile revealed at least six proteases, including serine, metal, and perhaps cysteine types. There were similar amounts of protease secreted by the closely related speciesBacillus cereusandBacillus thuringiensis, but the patterns differed. Among the pXO1 plasmid-encoded proteins, there is a tetratricopeptide protein designated Cot43 that is related to the Rap proteins ofBacillus subtilisand the PlcR pleiotropic regulator of secreted enzymes and toxins inB. thuringiensis. A disruption of thecot43gene resulted in overproduction of several proteases to a somewhat greater extent than in the plasmid-cured strain. Transformation of either of these strains with a clone of thecot43gene resulted in the inhibition of accumulation of some of the proteases and induction of at least one. On the basis oflacZfusions, transcription of thecot43gene increased in late exponential cells at the time of protease accumulation. The expression oflacZfusions to the upstream regions of twoB. anthracisextracellular protease genes was greater in the strain with the disruption ofcot43than in the Sterne strain, indicating regulation at the level of transcription. InB. anthracis, a pXO1 plasmid-encoded protein directly modulates or indirectly regulates the transcription of genes for several chromosomally encoded extracellular proteases.
Novel Roles of
ohrR
-
ohr
in
Xanthomonas
Sensing, Metabolism, and Physiological Adaptive Response to Lipid Hydroperoxide
Authors: Klomsiri Chananat , Panmanee Warunya , Dharmsthiti Saovanee , Vattanaviboon Paiboon , Mongkolsuk Skorn 
Published: April 2005

ABSTRACT

Lipid hydroperoxides are highly toxic to biological systems. Here, the
Xanthomonas campestris
pv. phaseoli sensing and protective systems against linoleic hydroperoxide (LOOH) were investigated by examining the phenotypes, biochemical and regulatory characteristics of various
Xanthomonas
mutants in known peroxide resistance pathways. Analysis of LOOH resistance levels indicates that both alkyl hydroperoxide reductase (AhpC) and organic hydroperoxide resistance enzyme (Ohr) have important and nonredundant roles in the process. Nonetheless, inactivation of
ohr
leads to a marked reduction in LOOH resistance levels. The regulatory characteristics of an
ohr
mutant add further support to its primary role in LOOH protection. Northern analysis shows that LOOH had differential effects on induction of
ahpC
and
ohr
expression with the latter being more sensitive to the inducer. Analysis of the
ahpC
and
ohr
promoters confirmed that the LOOH-dependent induction of these promoters is mediated by the transcription regulators OxyR and OhrR, respectively. Using the in vivo promoter assays and the in vitro gel mobility shift assay, we show that LOOH directly oxidized OhrR at the sensing residue Cys-22 leading to its inactivation. In addition, physiological analysis shows that pretreatment of
X. campestris
pv. phaseoli with a sublethal dose of LOOH induced high levels of resistance to subsequent exposure to lethal concentrations of LOOH. This novel LOOH-induced adaptive response requires a functional
ohrR-ohr
operon. These data illustrate an important novel physiological role for the
ohrR-ohr
system in sensing and inactivating lipid hydroperoxides.
Evidence based guidelines for the prevention, identification, and management of occupational asthma
Authors: Nicholson P J , Cullinan P , Newman Taylor A J , Burge P S , Boyle C 
Published: April 2005

Background:Occupational asthma is the most frequently reported work related respiratory disease in many countries. This work was commissioned by the British Occupational Health Research Foundation to assist the Health and Safety Executive in achieving its target of reducing the incidence of occupational asthma in Great Britain by 30% by 2010.Aim:The guidelines aim to improve the prevention, identification, and management of occupational asthma by providing evidence based recommendations on which future practice can be based.Methods:The literature was searched systematically using Medline and Embase for articles published in all languages up to the end of June 2004. Evidence based statements and recommendations were graded according to the Royal College of General Practitioner’s star system and the revised Scottish Intercollegiate Guidelines Network grading system.Results:A total of 474 original studies were selected for appraisal from over 2500 abstracts. The systematic review produced 52 graded evidence statements and 22 recommendations based on 223 studies.Discussion:Evidence based guidelines have become benchmarks for practice in healthcare and the process used to prepare them is well established. This evidence review and its recommendations focus on interventions and outcomes to provide a robust approach to the prevention, identification, and management of occupational asthma, based on and using the best available medical evidence. The most important action to prevent cases of occupational asthma is to reduce exposure at source. Thereafter surveillance should be performed for the early identification of symptoms, including occupational rhinitis, with additional functional and immunological tests where appropriate. Effective management of workers suspected to have occupational asthma involves the identification and investigation of symptoms suggestive of asthma immediately they occur. Those workers who are confirmed to have occupational asthma should be advised to avoid further exposure completely and early in the course of their disease to offer the best chance of recovery.
Diagnostic Performance of Nanoparticle-Enhanced Magnetic Resonance Imaging in the Diagnosis of Lymph Node Metastases in Patients With Endometrial and Cervical Cancer
Authors: Rockall Andrea G. , Sohaib Syed A. , Harisinghani Mukesh G. , Babar Syed A. , Singh Naveena , Jeyarajah Arjun R. , Oram David H. , Jacobs Ian J. , Shepherd John H. , Reznek Rodney H. 
Published: April 2005

Purpose Lymph node metastases affect management and prognosis of patients with gynecologic malignancies. Preoperative nodal assessment with computed tomography or magnetic resonance imaging (MRI) is inaccurate. A new lymph node–specific contrast agent, ferumoxtran-10, composed of ultrasmall particles of iron oxide (USPIO), may enhance the detection of lymph node metastases independent of node size. Our aim was to compare the diagnostic performance of MRI with USPIO against standard size criteria. Methods Forty-four patients with endometrial (n = 15) or cervical (n = 29) cancer were included. MRI was performed before and after administration of USPIO. Two independent observers viewed the MR images before lymph node sampling. Lymph node metastases were predicted using size criteria and USPIO criteria. Lymph node sampling was performed in all patients. Results Lymph node sampling provided 768 pelvic or para-aortic nodes for pathology, of which 335 were correlated on MRI; 17 malignant nodes were found in 11 of 44 patients (25%). On a node-by-node basis, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) by size criteria were 29%*, 99%, 56%, and 96%, and by USPIO criteria (reader 1/reader 2) were 93%/82%* (*P = .008/.004), 97%/97%, 61%/59%, and 100%/99%, respectively (where [*] indicates the statistical difference of P = x/x between the two results marked by the asterisk). On a patient-by-patient basis, sensitivity, specificity, PPV, and NPV by size criteria were 27%*, 94%, 60%, and 79%, and by USPIO criteria (reader 1/reader 2) were 100%/91%* (*P = .031/.06), 94%/87%, 82%/71%, and 100%/96%, respectively. The κ statistic was 0.93. Conclusion Lymph node characterization with USPIO increases the sensitivity of MRI in the prediction of lymph node metastases, with no loss of specificity. This may greatly improve preoperative treatment planning.
Efficient Method for the Lactonization of ω-Hydroxycarboxylic Acids with Di-2-thienyl Carbonate by the Promotion of Catalytic Amounts of DMAP and Hf(OTf)4
Authors: Oohashi Yoshiaki , Fukumoto Kentarou , Mukaiyama Teruaki 
Published: April 2005

Abstract
An efficient method for the synthesis of macrolides from ω-hydroxycarboxylic acids is established by using an equimolar amount of di-2-thienyl carbonate (2-DTC) and catalytic amounts of 4-(dimethylamino)pyridine (DMAP) and group 4 metal triflates such as hafnium(IV) trifluoromethanesulfonate (Hf(OTf)4).
Cell‐cell interactions in regulating osteogenesis and osteoblast function
Authors: Stains Joseph P. , Civitelli Roberto 
Published: April 2005

AbstractEndochondral bone formation requires an elaborate interplay among autocrine, paracrine, and endocrine signals, positional cues, and cell‐cell contacts to mediate the complex three‐dimensional architecture and function of the skeleton. Embryonic bone development occurs by migration, aggregation, and condensation of immature mesenchymal progenitor cells to form the cartilaginous anlage. Upon vascular invasion, the cartilaginous scaffold is colonized and subsequently mineralized by osteoblasts. Likewise, bone remodeling in the adult skeleton is a dynamic process that requires coordinated cellular activities among osteoblasts, osteocytes, and osteoclasts to maintain bone homeostasis. This review examines the role of cell‐cell interactions mediated by adherens junctions formed by cadherins and communicative gap junctions formed by connexins in regulating bone development and osteogenic function. Birth Defects Research (Part C) 75:72–80, 2005. © 2005 Wiley‐Liss, Inc.
Further studies on knockout mice lacking a functional dynein heavy chain (MDHC7). 2. A developmental explanation for the asthenozoospermia
Authors: Woolley David M. , Neesen Juergen , Vernon Geraint G. 
Published: April 2005

AbstractMale mice had been previously generated in which the inner dynein arm heavy chain 7 gene (MDHC7) was disrupted. MDHC7−/− animals show asthenozoospermia and are sterile. Very few of their spermatozoa can achieve forward progression, but for those that can, we add here the information (1) that the three‐dimensional aspects of their movement are normal; (2) that their maximum velocity is less than that of wild‐type controls; and (3) that they are entirely unable to penetrate media of raised viscosity (25–4,000 cP). However, the large majority of the spermatozoa can achieve only a low amplitude vibration. In these sperm we find, using electron microscopy, that the outer dense fibres retain attachments to the inner surface of the mitochondria. Such attachments are present in normal epididymal mouse spermatozoa but are broken down as soon as the sperm become motile on release from the epididymis. The attachments are presumed to be essential during midpiece development and, afterwards, to require a threshold level of force to loosen them and so permit the sliding displacements necessary for normal bending. We presume that the disruption of the inner dynein arm heavy chain gene, MDHC7, means that there is insufficient force to overcome the attachments, for all but a few spermatozoa. Cell Motil. Cytoskeleton 61:74–82, 2005. © 2005 Wiley‐Liss, Inc.
A simplified formula of Laplace inversion based on wavelet theory
Authors: Wang Jizeng , Gao Huajian 
Published: April 2005

AbstractA simple formula $f(x)\approx (1/2^{n+1} \pi) \sum \nolimits_{k=-\infty}^{+ \infty}\tilde{f}(\beta +ik/2^{n})e^{x(\beta + ik/{2^{n}})}$ for Laplace inverse transform is derived based on the wavelet theory. The efficiency and robustness are demonstrated through numerical examples. Copyright © 2005 John Wiley & Sons, Ltd.
Thermal convection and related instabilities in models of crystal growth from the melt on earth and in microgravity: Past history and current status
Authors: Lappa Marcello 
Published: April 2005

AbstractThe paper presents a comparative study of a number of theoretical/experimental/numerical results concerning the dynamics of natural (gravitational), Marangoni and related mixed convection in various geometrical models of widely‐used technologies for the production of single‐crystalline materials (Horizontal and vertical Bridgman growth, Czochralski method, Floating Zone Technique). Emphasis is given to fundamental knowledge provided over the years by landmark analyses as well as to very recent contributions. Such a knowledge is of paramount importance since it is validating new, more complex models, accelerating the current trend towards predictable and reproducible phenomena and finally providing an adequate scientific foundation to industrial processes which are still conducted on a largely empirical basis. A deductive approach is followed with fluid‐dynamic systems of growing complexity being treated as the discussion progresses. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Room, low, and high temperature dehydration and phase transitions of kernite in vacuum and in air
Authors: Sennova N. A. , Bubnova R. S. , Filatov S. K. , Paufler P. , Meyer D. C. , Levin A. A. , Polyakova I. G. 
Published: April 2005

AbstractKernite Na2B4O6(OH)2·3H2O dehydration in air at high temperature and in vacuum at room temperature has been studied. It was found that kernite easily dehydrates forming a new phase‐I both on heating and in vacuum. The chemical formula Na2B4O6(OH)2·1.5H2O of the new phase‐I has been estimated on the basis of thermogravity analysis. It is triclinic with the unit cell parameters a = 7.047(8), b = 8.76(1), c = 13.08(2) Å, α = 93.40(9), β = 95.32(9), γ = 90.28(9)° changing slightly on pressure reduction. Due to the relatively low temperature (353 K) and reversibility of the kernite ⟷ phase‐I transition an anion of the new phase‐I likely consists of the same chains [B4O6(OH)2]2– like in kernite structure. The high anisotropy of kernite thermal expansion was explained by approaching of NaO chains due to the initial removing of water molecules from kernite crystal structure. The behaviour of the new phase‐I at low temperatures in vacuum was also investigated. A formation of an additional new phase II has been detected at the temperature of 93 K. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of substrate temperature on the properties of vacuum evaporated InSb films
Authors: Senthilkumar V. , Venkatachalam S. , Viswanathan C. , Gopal S. , Narayandass Sa. K. , Mangalaraj D. , Wilson K. C. , Vijayakumar K. P. 
Published: April 2005

AbstractIndium Antimonide (InSb) thin films were grown onto well cleaned glass substrates at different substrate temperatures (303, 373 and 473 K) by vacuum evaporation. The elemental composition of the deposited InSb film was found to be 52.9% (In) and 47.1% (Sb). X‐ray diffraction studies confirm the polycrystallinity of the films and the films show preferential orientation along the (111) plane. The particle size (D), dislocation density (δ) and strain (ε) were evaluated. The particle size increases with the increase of substrate temperature, which was found to be in the range from 22.36 to 32.59 nm. In Laser Raman study, the presence of longitudinal mode (LO) confirms that the deposited films were having the crystalline nature. Raman peak located at 191.26 cm–1 shift towards the lower frequencies and narrows with increase in deposition temperature. This indicates that the crystallinity is improved in the films deposited at higher substrate temperatures. Hall measurements indicate that the films were p‐type, having carrier concentration ≅1016 cm–3 and mobility (4–7.7) ×103 cm2/Vs. It is observed that the carrier concentration (N) decreases and the Hall mobility (μ) increases with the increase of substrate temperature. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A proposal of adaptive protocol relay capability for real‐time media with allowable delay
Authors: Otsuki Hideki , Yamaoka Katsunori , Sakai Yoshinori 
Published: April 2005

AbstractIn the video and speech transmission using packets, the media synchronization control is applied, especially in the system for real‐time transmission. In the system containing the media synchronization, the allowable time delay is defined, and the packet after this delay limit is discarded. In protocols such as ARQ (automated repeat request), where the packet retransmission is executed for error correction, if the delay or the error rate of the channel is large, the packet delay is greatly increased when an error occurs. The packet is discarded when the packet delay exceeds the allowable delay, which produces degradation of quality. This paper proposes an adaptive protocol relay system considering the allowable delay, in order to cope with this problem. In the adaptive protocol relay system, the protocol relay is executed at the relay node, when a certain condition for each packet is satisfied. By reducing the time spent in the packet retransmission due to the error, the number of packets that do not arrive at the receiving terminal within the allowable delay is reduced. This paper examines the effect of the protocol relay on the packet discard rate, when the proposed method is used. The condition for the adaptive control at the relay node is also discussed. © 2005 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 88(8): 50–59, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10031
Coordinating interstream rate control scheme using layered multicast
Authors: Kawada Masato , Morikawa Hiroyuki , Aoyama Tomonori 
Published: April 2005

AbstractIn multicast delivery in a network environment with various bandwidth limitations, it is effective to apply the layered multicast technique, which realizes delivery at a reception rate matched to each receiver, although the rate is set discretely. This paper assumes a multimedia session such as a multichannel broadcast or a video conference, composed of multiple streams. In such an application, it is desirable from the viewpoint of efficient use of bandwidth that not only should the streams be transmitted with stable quality, but that the rate should be assigned according to requests, such as attention to the speaker. However, it is difficult to achieve the above goal by directly applying the conventional layered multicast rate control technique, since each stream controls the rate independently. From such a viewpoint, this paper presents a session level mechanism covering multiple layered streams. A multiple streams controller (MSC) is introduced into each receiver, and each MSC autonomously controls the reception rate with interstream coordination in the session. The MSC monitors the reception state of the multiple streams simultaneously and estimates the bandwidth information on the bottleneck link and the set of transiting streams, based on the detected congestion data. Based on the estimation, the learning efficiency of the reception rate is improved and rate assignment control over the streams is applied. An evaluation is performed by computer simulation, and it is shown that the reception quality of the stream is improved by applying the proposed method, and that the reception rate can be coordinated among the streams. © 2005 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 88(8): 18–31, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20142
Essential oil composition and chemoarrays of menthol mint (Mentha arvensis L. f. piperascens Malinvaud ex. Holmes) cultivars
Authors: Singh A. K. , Raina V. K. , Naqvi A. A. , Patra N. K. , Kumar Birendra , Ram P. , Khanuja S. P. S. 
Published: April 2005

AbstractThe chemical composition of essential oils isolated from six different cultivars of corn mint grown at CIMAP Field Station, Pantnagar, were compared: menthol (77.5–89.3%) was the main constituent of all the cultivars, followed by menthone (0.3–7.9%) and isomenthone (3.7–6.1%). The oil of MAS‐1 cultivar contained the highest concentration of menthol (89.3%) but the lowest percentage of menthone (0.3%), while isomenthone was not detected. Although the compositions of the six oils were similar, quantitative differences in the concentration of some constituents was observed. Yield and quality appraisals in the study led to the identification of the cultivars Kosi, Himalaya and Damroo as the most potent genotypes for maintaining mint crop diversity and productivity stability. Copyright © 2005 John Wiley & Sons, Ltd.
Two‐level Haseman‐Elston regression for general pedigree data analysis
Authors: Wang Tao , Elston Robert C. 
Published: April 2005

AbstractThe Haseman‐Elston (HE) (Haseman and Elston [1972] Behav Genet 2:3–19) method is widely used in genetic linkage studies for quantitative traits. We propose a new version of the HE regression model, a two‐level HE regression model (tHE) in which the variance‐covariance structure of family data is modeled under the framework of multiple‐level regression. An iterative generalized least squares (IGLS) algorithm is adopted to handle the varying variance‐covariance structures across families in a simple fashion. In this way, the tHE can compete favorably with any current version of HE in that it can naturally make use of all the trait information available in any general pedigree, simultaneously incorporate individual‐level and pedigree‐level covariates, marker genotypes for linkage (i.e., the number of allele shared identically by descent [IBD]), and marker alleles for association. Under the assumption of normality, the method is asymptotically equivalent to the usual variance component model for detecting linkage. For the situation where the assumption of normality is critical, a robust globally consistent estimator of the quantitative trait locus (QTL) variance is available. Complex genetic mechanisms, including gene‐gene interaction, gene‐environmental interaction, and imprinting, can be directly modeled in this version of HE regression. Genet. Epidemiol. © 2005 Wiley‐Liss, Inc.