bluuebunny/crossref_metadata_2025 huggingface dataset:
Workplace learning: a trade union failure to service needs
Authors: Stroud Dean , Fairbrother Peter
Published: January 2008

Purpose

The purpose of this paper is to open up discussion about the relationship between trade unions and workplace learning.

Design/methodology/approach

The paper is based on an analysis of a series of case‐studies of restructuring in the European steel industry, incorporating interviews, observation and documentary analysis.

Findings

The paper argues that trade unions often fail to address the significance of workplace learning for members, because they address workplace learning as a service. This approach fails to exploit opportunities and possibilities to extend workplace‐learning provisions, and thereby meet the wider learning and employability enhancing needs of members. The outcome is that trade union involvement in skill formation and workplace learning is marginal, and contributes to the perpetuation of traditional sector practices and regressive learning provisions.

Research limitations/implications

The paper focuses on a discussion of trade union involvement in workplace learning in the European steel industry. The implications for workplace learning practices more generally, are limited to industries where trade unions (and companies/industry) organise in relation to training and learning agendas in similar ways – and in relation to industries undergoing similar process of restructuring and “modernisation”.

Practical implications

The paper provides a critique of trade union service approaches to learning agendas and highlights for policy‐makers gaps in current learning provisions within industry.

Originality/value

This paper makes an original contribution to debates concerned with trade union involvement and participation in workplace learning. It focuses on workplace inequities in training provision, and the implications for the future of unions and the employability prospects of workforces within the European steel industry.
Online training: the value of capturing trainee reactions
Authors: Long Lori K. , DuBois Cathy Z. , Faley Robert H.
Published: January 2008

Purpose

Despite years of advice from researchers that trainee reactions provide training evaluation information that is of very limited use, trainee reactions remain the most commonly used measure of training effectiveness. Because the technology that supports online training facilitates the collection of trainee reaction information during and after training, organizations will likely expand their use of trainee reactions in training evaluation. Thus, the need to understand the utility of trainee reactions in online training is significant. The purpose of this study is to propose a model of trainee reactions based upon the theory of reasoned action and the technology acceptance model.

Design/methodology/approach

The model was tested using students participating in online training courses provided by a large landscaping company based in the USA.

Findings

Analyses provided partial support for the model. Findings include a negative relationship between computer anxiety and pre‐training motivation, a positive main effect on perceived effort for both pre‐training motivation and trainee reactions, and a positive relationship between trainee reactions and intent to take future online courses.

Research limitations/implications

The generalizability of the results of this study is limited due to the use of student subjects. Also, a small sample size limited the ability to test the full model using path analytic testing.

Originality/value

These results provide meaningful guidance both for researchers and for practitioners responsible for the design and implementation of online training courses.
Interim reflections on the corporate university and SME academy business development innovation and its diffusion
Authors: Dealtry Richard
Published: January 2008

Purpose

The purpose of this paper is to reflect on and inform about learning points from ECUANET, a two‐year duration best practice action research and transnational networking project as it approaches its final stage.

Design/methodology/approach

The paper explicates the key positive and obfuscating dynamics that the project team have had to, and will have to conjure with, in reaching its recommendations about the evolution of best practice in corporate university and enterprise academy design and management. The project partners have operated a voluntary or self selection process in their recruitment of corporate partner organisations to participate in the project action research case study work. The research methodology was based upon the corporate university blueprint architecture and browser toolkit to provide depth in practice evidence and a searchable database for comparative case to case practice evaluation of the key performance indicators (KPIs)

Findings

It was found that the corporate university organisation and business development concept is a subject area which is either well understood by company management and education institutions or there is considerable confusion about its role and purpose. This comment does not apply comfortably and consistently universally as there are very different states of maturity, adoption and interpretation in the concept's development and practice across the world region by region. From a wide and diverse portfolio of companies and organisations who where invited to participate in the action research case studies those who accepted have one very important characteristic in common: they are all intensively engaged in managing a major innovation, i.e. they already have the commitment and fortitude to making new ideas work in practice. The experience of this project confirms that to be successful in this turbulent era of intensive new learning management, there needs to be continuous commitment to engendering innovation diffusion in both strategic and tactically inspired new learning process management. In addition it also demands serious reflection about the creative nature of the learning leadership role and also the style of its management.

Originality/value

The a priori browser based corporate university blueprint model architecture employed in the empirical case study research mode proved to have both the depth and flexibility to provide a high quality evaluative framework and capture all the dynamics relating to the key variables in good corporate university design and management. The data base of case foundation information, KPIs and best practice outcomes will be one of the most comprehensive and world class quality reference sources published to date.
The nature of randomness
Authors: Powers Michael R.
Published: January 2008

Purpose

In this two‐part series, this paper seeks to consider certain intriguing aspects of randomness, the basic mathematical concept used to model financial risk and other unknown quantities in the physical world.

Design/methodology/approach

Part 1 applies concepts from quantum physics and algorithmic information theory to distinguish between knowable complexity and unknowable complexity.

Findings

In Part 1, it is found that Heisenberg's uncertainty principle can be used to provide concrete examples of random variables, and that the Kolmogorov/Chaitin notion of algorithmic complexity can be used to define the formal concept of randomness.

Originality/value

The two‐part series explores the underlying nature of randomness in terms of both its physical/mathematical properties and its role in human cognition.
Corporate hedging and risk management theory: evidence from Polish listed companies
Authors: Marek Klimczak Karol
Published: January 2008

Purpose

This paper aims to provide a comprehensive empirical assessment of major contemporary corporate hedging theories, i.e. financial theory, agency theory, stakeholder theory and new institutional economics.

Design/methodology/approach

Hypotheses regarding the determinants of hedging are tested on a sample of 150 companies listed on the Warsaw Stock Exchange. The panel covers a period of five years (2001‐2005). Unlike in previous research the tests are organised around theories rather than individual hypotheses. In addition to classic tests, CART analysis is used to verify hypotheses.

Findings

The results show low empirical verification of all theories considered. However, the results support some single hypotheses. Tests identified currency exposure, market‐to‐book value, IT and service sectors and size as being determinants of hedging.

Research limitations/implications

The results provide evidence for the low usefulness of contemporary theories. New models are needed to explain hedging behaviour more accurately.

Practical implications

The results identify characteristics shared by firms that use hedging. Companies considering implementing hedging can check whether they share these characteristics.

Originality/value

This paper adds to risk management research by providing strong empirical evidence of theory verification status. It can serve as a base for future conceptual research.
Development in Islamic banking: a financial risk‐allocation approach
Authors: Mansoor Khan M. , Ishaq Bhatti M.
Published: January 2008

Purpose

The core objective of this paper is to direct worldwide attention towards the unparalleled development in Islamic banking, its infrastructures and supporting institutions in recent years. This paper articulates the case for Islamic banking in a very comprehensive and effective manner. It depicts Islamic banking as a growing discipline adding more ethical, competitive and diversified tools and systems into global finance. It highlights the paradigm, theory and practice, achievements, pitfalls and future prospects of Islamic banking.

Design/methodology/approach

The paper deals with the Islamic paradigm of borrowing, lending and investment. It presents the conceptual model and practice of Islamic banking. It covers other related issues over the recent development of Islamic banking across the globe.

Findings

The paper observes that Islamic banking has made unprecedented progress over recent years. The Middle East, South Asia and the Indian Subcontinent have emerged as hubs of Islamic banking. Western conventional regulators and investors and other agents have also shown a greater interest in and a receptive attitude towards Islamic banking. Despite all this, Islamic banking has been facing some core problems and challenges that will have deep impacts on its future growth and development.

Research limitations/implications

The paper deals with concepts, information and other facts on Islamic banking that are not supported by any statistical analysis and empirical evidence. Thus this paper may be regarded as being subjective in its real essence.

Originality/value

The paper educates Western market players about Islamic banking tools and systems in their own language so as to bridge the gap between conventional and Islamic banking disciplines. It suggests that Islamic banking is an equity‐based system with conventional features. It makes an important point – that the main players from both the Islamic and conventional streams have a good opportunity to pool their expertise and resources to come up with better solutions in business, investment and finance.
Effect of exchange‐rate volatility on foreign direct investment in Sub‐Saharan Africa
Authors: Kyereboah‐Coleman Anthony , Agyire‐Tettey Kwame F.
Published: January 2008

Purpose

The present study aims at using a broader data set and longer time frame coupled with a relatively rigorous and robust methodology to examine the effect of real exchange rate volatility on foreign direct investment (FDI) in a small and developing country such as Ghana.

Design/methodology/approach

Time series data covering the period 1970‐2002 were used. ARCH and GARCH models were employed for the determination of real exchange rate volatility, and co‐integration and ECM were used to determine both the short‐ and the long‐term relationships.

Findings

The study showed that the volatility of the real exchange rate has a negative influence on FDI inflow and that the liberalization process has not led to a greater inflow of FDI in Ghana. It is also revealed that while both the stock of FDI and political factors are likely to attract FDI, most foreign investors do not consider the size of the market in making a decision to invest or otherwise in Ghana.

Originality/value

The main contribution of the study is its departure from the use of ratios in examining the effect of real exchange rate risk on FDI to a more rigorous and robust methodology, coupled with the fact that studies of this nature are virtually non‐existent in Ghana.
Risk minimization under budget constraints
Authors: Lee Kiseop
Published: January 2008

Purpose

The purpose of this paper is to find the optimal hedging strategy when an investor has budget constraints on both the initial capital and the future cash flow.

Design/methodology/approach

The paper follows the utility minimization of the total cost, using convex utility functions on both initial capital and future cash flows.

Findings

Closed‐form solutions of optimal hedging strategies are found in some specific but popular cases. It is also found that this method corresponds to the local risk minimization method in quadratic hedging.

Research limitations/implications

Hedging strategies are calculated for only two popular choices. One may want to calculate hedging strategies for other popular utility functions such as power utility or HARA utility.

Practical implications

When a trader has some budget constraint in both initial capital and future cash flows, this paper gives a simple alternative.

Originality/value

Budget constraints on both initial capital and future cash flow are new to this kind of study. Connection to the local risk minimization strategy is original too.
Facts, fantasies and fun in epithelial physiology
Authors: Boyd C. A. R.
Published: January 2008

The hallmark of epithelial cells is their functional polarization. It is those membrane proteins that are distributed differentially, either to the apical or to the basal surface, that determine epithelial physiology. Such proteins will include ‘pumps’, ‘channels’ and ‘carriers’, and it is the functional interplay between the actions of these molecules that allows the specific properties of the epithelium to emerge. Epithelial properties will additionally depend on: (a) the extent to which there may be a route between adjacent cells (the ‘paracellular’ route); and (b) the folding of the epithelium (as, for example, in the loop of Henle). As for other transporters, there is polarized distribution of amino‐acid carriers; the molecular basis of these is of considerable current interest with regard to function, including ‘inborn errors’ (amino‐acidurias); some of these transporters have additional functions, such as in the regulation of cell fusion, in modulating cell adherence and in activating intracellular signalling pathways. Collaboration of physiologists with fly geneticists has generated new insights into epithelial function. One example is the finding that certain amino‐acid transporters may act as ‘transceptors’ and play a role as sensors of the extracellular environment that then regulate intracellular pathways controlling cell growth.
Renal (pro)renin receptor upregulation in diabetic rats through enhanced angiotensin AT1 receptor and NADPH oxidase activity
Authors: Siragy Helmy M. , Huang Jiqian
Published: January 2008

Recent studies have demonstrated the presence of the (pro)renin receptor (PRR) in the glomerular mesangium and the subendothelial layer of the renal arteries. We hypothesized that diabetes upregulates PRR expression through enhanced angiotensin subtype 1 (AT1) receptor–NADPH oxidase cascade activity. Using real‐time polymerase chain reaction, Western blot analysis and immunostaining, we studied renal localization of the PRR in the streptozotocin‐induced diabetic rat model and in response to 1 week of treatment with the AT1 receptor blocker valsartan (10 mg kg−1 day−1), the angiotensin AT2 receptor blocker PD123319 (0.5 mg kg−1 day−1) or the NADPH oxidase inhibitor diphenylene iodonium (DPI; 0.5 mg kg−1 day−1) 6 weeks post‐induction of diabetes. Both PRR mRNA and protein were expressed constitutively in the kidneys of normal rat renal cortex and medulla, mainly in glomerular mesangium, proximal, distal and collecting tubules. Compared with normal rats (100%), diabetic rats demonstrated an increase in renal PRR mRNA (184%), protein (228%) and immunostaining. Valsartan and DPI prevented the increase in the PRR mRNA (106 and 126%, respectively), protein (97 and 140%, respectively) and immunostaining that was seen in the kidneys of diabetic rats. The AT2 blocker PD123319 did not have significant effects on PRR mRNA (157%) or protein expression (200%) in the kidneys of diabetic rats. These results demonstrate that the PRR is constitutively expressed in renal glomeruli and tubules. Expression of the PRR is upregulated in diabetes via enhancement of AT1 receptor–NADPH oxidase activity.
Tissue‐specific regulation of ACE/ACE2 and AT1/AT2 receptor gene expression by oestrogen in apolipoprotein E/oestrogen receptor‐α knock‐out mice
Authors: Brosnihan K. Bridget , Hodgin Jeffrey B. , Smithies Oliver , Maeda Nobuyo , Gallagher Patricia
Published: January 2008

Angiotensin‐converting enzyme (ACE) and ACE2 and the AT1 and AT2 receptors are pivotal points of regulation in the renin–angiotensin system. ACE and ACE2 are key enzymes in the formation and degradation of angiotensin II (Ang II) and angiotensin‐(1–7)(Ang‐(1–7)). Ang II acts at either the AT1 or the AT2 receptor to mediate opposing actions of vasoconstriction or vasodilatation respectively. While it is known that oestrogen acts to downregulate ACE and the AT1 receptor, its regulation of ACE2 and the AT2 receptor and the involvement of a specific oestrogen receptor subtype are unknown. To investigate the role of oestrogen receptor‐α (ERα) in the regulation by oestrogen of ACE/ACE2 and AT1/AT2 mRNAs in lung and kidney, ovariectomized female mice lacking apolipoprotein E (ee) with the ERα (AAee) or without the ERα (ααee) were treated with 17β‐oestradiol (6 μg day−1) or placebo for 3 months. ACE, ACE2, AT1 receptor and AT2 receptor mRNAs were measured using reverse transcriptase, real‐time polymerase chain reaction. In the kidney, 17β‐oestradiol showed 1.7‐fold downregulation of ACE mRNA in AAee mice, with 2.1‐fold upregulation of ACE mRNA in ααee mice. 17β‐Oestradiol showed 1.5‐ and 1.8‐fold downregulation of ACE2 and AT1 receptor mRNA in AAee mice; this regulation was lost in ααee mice. 17β‐Oestradiol showed marked (81‐fold) upregulation of the AT2 receptor mRNA in AAee mice. In the lung, 17β‐oestradiol treatment had no effect on AT1 receptor mRNA in AAee mice, but resulted in a 1.5‐fold decreased regulation of AT1 mRNA in ααee mice. There was no significant interaction of oestrogen with ERα in the lung for ACE, ACE2 and AT2 receptor genes. These studies reveal tissue‐specific regulation by 17β‐oestradiol of ACE/ACE2 and AT1/AT2 receptor genes, with the ERα receptor being primarily responsible for the regulation of kidney ACE2, AT1 receptor and AT2 receptor genes.
Differential regulation of renal angiotensin‐converting enzyme (ACE) and ACE2 during ACE inhibition and dietary sodium restriction in healthy rats
Authors: Hamming I. , Van Goor H. , Turner A. J. , Rushworth C. A. , Michaud A. A. , Corvol P. , Navis G.
Published: January 2008

Angiotensin‐converting enzyme (ACE) 2 is thought to counterbalance ACE by breakdown of angiotensin (Ang) II and formation of Ang(1–7). Both enzymes are highly expressed in the kidney, but reports on their regulation differ. To enhance our understanding of the regulation of renal ACE and ACE2, we investigated renal ACE and ACE2 expression during conditions of physiological (low‐sodium diet) and pharmacological changes (ACE inhibition) in activity of the renin–angiotensin–aldosterone system (RAAS). Healthy rats were treated with vehicle or lisinopril with either a control or a low‐sodium diet, and renal ACE2, ACE and plasma angiotensins were studied. During vehicle treatment, low sodium reduced renal ACE mRNA and activity without affecting ACE2 mRNA or activity and plasma Ang(1–7) and Ang II balance. Lisinopril significantly reduced renal ACE activity without affecting renal ACE2 activity. During ACE inhibition, low sodium reduced both ACE and ACE2 mRNA without affecting ACE2 activity or further reducing ACE activity. Measurements of renal neprilysin activity revealed no significant differences between any of the treatment groups. Plasma Ang(1–7) and Ang II balance is positively shifted towards the beneficial vasopeptide Ang(1–7) by the ACE inhibitor lisinopril, especially during a low sodium intake. In conclusion, modulation of the RAAS, by low sodium intake or ACE inhibition, does not affect renal ACE2 despite major variations in renal ACE. Thus, ACE and ACE2 are differentially regulated by low sodium and ACE inhibition. Therefore, we propose that the beneficial effects of ACE inhibitors are predominantly mediated by modulation of ACE and not ACE2. Whether this also applies to renal disease conditions should be investigated in future studies.
Classical and quantum behavior of dynamical systems defined by functions of solvable Hamiltonians
Authors: Barbero G. J. Fernando , Garay Iñaki , Villaseñor Eduardo J. S.
Published: January 2008

We discuss the classical and quantum mechanical evolution of systems described by a Hamiltonian that is a function of a solvable one, both classically and quantum mechanically. The case in which the solvable Hamiltonian corresponds to the harmonic oscillator is emphasized. We show that, in spite of the similarities at the classical level, the quantum evolution is very different. In particular, this difference is important in constructing coherent states, which is impossible in most cases. The class of Hamiltonians we consider is interesting due to its pedagogical value and its applicability to some open research problems in quantum optics and quantum gravity.
Student understanding of control of variables: Deciding whether or not a variable influences the behavior of a system
Authors: Boudreaux Andrew , Shaffer Peter S. , Heron Paula R. L. , McDermott Lillian C.
Published: January 2008

The ability of adult students to reason on the basis of the control of variables was the subject of an extended investigation. This paper describes the part of the study that focused on the reasoning required to decide whether or not a given variable influences the behavior of a system. The participants were undergraduates taking introductory Physics and K–8 teachers studying physics and physical science in inservice institutes and workshops. Although most of the students recognized the need to control variables, many had significant difficulty with the underlying reasoning. The results indicate serious shortcomings in the preparation of future scientists and in the education of a scientifically literate citizenry. There are also strong implications for the professional development of teachers, many of whom are expected to teach control of variables to young students.
Would Bohr be born if Bohm were born before Born?
Authors: Nikolić Hrvoje
Published: January 2008

I discuss a hypothetical historical context in which a Bohm-like deterministic interpretation of the Schrödinger equation is proposed before the Born probabilistic interpretation and argue that in such a context the Copenhagen (Bohr) interpretation would probably have not achieved great popularity among physicists.
The effect of spin on the flight of a baseball
Authors: Nathan Alan M.
Published: January 2008

Measurements are presented of the Magnus force on a spinning baseball. The experiment utilizes a pitching machine to project the baseball horizontally, a high-speed motion analysis system to determine the initial velocity and angular velocity and to track the trajectory over 5m of flight, and a ruler to measure the total distance traversed. Speeds in the range v=50–110mph and spin rates ω (topspin or backspin) in the range 1500–4500rpm were utilized, corresponding to Reynolds numbers of Re=(1.1–2.4)×105 and spin factors S≡Rω∕v in the range 0.090–0.595. Least-squares fits were used to extract the initial parameters of the trajectory and to determine the lift coefficients. Comparison is made with previous measurements and parametrizations, and implications for the effect of spin on the flight of a baseball are discussed. The lift coefficient CL is found not to depend strongly on v at fixed values of S.
Revisiting the radiation from a suddenly moving sheet of charge
Authors: Chung J.-M.
Published: January 2008

We use Jefimenko’s formulas to give an alternative derivation (without introducing vector and scalar potentials) for the fields of a suddenly moving sheet of charge (Feynman’s example). We also comment on the nonlocal nature of Jefimenko’s formulas.
Testing a new voting machine question methodology
Authors: Reay N. W. , Li Pengfei , Bao Lei
Published: January 2008

A new question methodology has been developed and used with voting machines in large physics lecture classrooms. The methodology was tested by comparing student performance in voting machine and non-voting machine lecture sections during three consecutive electricity and magnetism quarters of introductory calculus-based physics. Data from The Conceptual Survey of Electricity and Magnetism and common examination questions indicates that students using voting machines achieved a significant gain in conceptual learning, and that voting machines reduced the gap between male and female student performances on tests. Surveys indicated that students were positive about the use of voting machines and believed that they helped them learn. The surveys also suggested that grading voting machines responses and/or overusing voting machines may lower student enthusiasm.
Quantum entanglement, fair sampling, and reality: Is the moon there when nobody looks?
Authors: Adenier Guillaume
Published: January 2008

In 1981 Mermin described a clever and simplified version of Bell’s theorem. He pointed out in a straightforward way that interpreting entanglement from a local realist point of view could be problematic. I propose an extended version of Mermin’s device that can be given a simple local realist interpretation by a sample selection bias. I argue that we still have no scientific reason to believe that the moon could not be there when nobody looks.
Variation in Prokaryotic Community Composition as a Function of Resource Availability in Tidal Creek Sediments
Authors: Edmonds Jennifer W. , Weston Nathanial B. , Joye Samantha B. , Moran Mary Ann
Published: January 2008

In anaerobic coastal sediments, hydrolytic and/or fermentative bacteria degrade polymeric material and produce labile intermediates, which are used by terminal metabolizers to complete the conversion of organic material to CO
2
. We used molecular approaches to evaluate the response of two bacterial terminal metabolizer groups from a coastal tidal creek sediments, sulfate reducers and methanogens, to controlled changes in carbon resource supply. Tidal creek sediment bioreactors were established in April and August 2004. For each date, intact sediment sections were continuously supplied with flowthrough seawater that was either unamended or amended with the high-molecular-weight polysaccharide dextran. Biogeochemical data indicate that the activity of fermenting bacteria and the terminal metabolizers was limited by organic carbon supply during both experiments, with a significant increase in net volatile fatty acid (VFA) production and rates of sulfate reduction and methanogenesis following dextran addition. Community composition (measured by using terminal restriction fragment length polymorphism analysis, and functional gene [
dsrA, mcrA
] clone libraries) changed from April to August. However, community composition was not different between amended and unamended cores within each month, despite the change in resource level. Moreover, there was no relationship between community richness and evenness with resource level. This lack of variation in community composition with C addition could be attributed to the dynamic environment these sediment communities experience in situ. Fluctuations in VFA concentrations are most likely very high, so that the dominant bacterial species must be able to outcompete other species at both high and low resource levels.
Two Different Tetracycline Resistance Mechanisms, Plasmid-Carried
tet
(L) and Chromosomally Located Transposon-Associated
tet
(M), Coexist in
Lactobacillus sakei
Rits 9
Authors: Ammor Mohammed Salim , Gueimonde Miguel , Danielsen Morten , Zagorec Monique , van Hoek Angela H. A. M. , de los Reyes-Gavilán Clara G. , Mayo Baltasar , Margolles Abelardo
Published: January 2008

Lactobacillus sakei
is extensively used as functional starter culture in fermented meat products. One of the safety criteria of a starter culture is the absence of potentially transferable antibiotic resistance determinants. However, tetracycline-resistant
L. sakei
strains have already been observed. In this paper, we show that tetracycline resistance in
L. sakei
Rits 9, a strain isolated from Italian Sola cheese made from raw milk, is mediated by a transposon-associated
tet
(M) gene coding for a ribosomal protection protein and a plasmid-carried
tet
(L) gene coding for a tetracycline efflux pump. pLS55, the 5-kb plasmid carrying the
tet
(L) gene, is highly similar to the pMA67 plasmid recently described for
Paenibacillus larvae
, a species pathogenic to honeybees. pLS55 could be transferred by electroporation into the laboratory strain
L. sakei
23K. While the
L. sakei
23K transformant containing pLS55 displayed an intermediate tetracycline resistance level (MIC, <32 μg/ml),
L. sakei
Rits 9, containing both tetracycline-resistant determinants, had a MIC of <256 μg/ml, suggesting that Tet L and Tet M confer different levels of resistance in
L. sakei
. Remarkably, in the absence of tetracycline, a basal expression of both genes was detected for
L. sakei
Rits 9. In addition, subinhibitory concentrations of tetracycline affected the expression patterns of
tet
(M) and
tet
(L) in different ways: the expression of
tet
(M) was induced only at high tetracycline concentrations, whereas the expression of
tet
(L) was up-regulated at lower concentrations. This is the first time that two different mechanisms conferring resistance to tetracycline are characterized for the same strain of a lactic acid bacterium.
Identification of
Campylobacter jejuni
Genes Involved in the Response to Acidic pH and Stomach Transit
Authors: Reid Anne N. , Pandey Reenu , Palyada Kiran , Naikare Hemant , Stintzi Alain
Published: January 2008

Campylobacter jejuni
causes food- and waterborne gastroenteritis, and as such it must survive passage through the stomach in order to reach the gastrointestinal tract. While little is known about how
C. jejuni
survives transit through the stomach, its low infectious dose suggests it is well equipped to sense and respond to acid shock. In this study, the transcriptional profile of
C. jejuni
NCTC 11168 was obtained after the organism was exposed to in vitro and in vivo (piglet stomach) acid shock. The observed down-regulation of genes encoding ribosomal proteins likely reflects the need to reshuffle energy toward the expression of components required for survival. Acid shock also caused
C. jejuni
to up-regulate genes involved in stress responses. These included heat shock genes as well as genes involved in the response to oxidative and nitrosative stress. A role for the chaperone
clpB
in acid resistance was confirmed in vitro. Some genes showed expression patterns that were markedly different in vivo and in vitro, which likely reflects the complexity of the in vivo environment. For instance, transit through the stomach was characterized by up-regulation of genes that encode products that are involved in the use of nitrite as a terminal electron acceptor and down-regulation of genes that are involved in capsular polysaccharide expression. In conclusion, this study has enabled us to understand how
C. jejuni
modulates gene expression in response to acid shock in vitro and to correlate this with gene expression profiles of
C. jejuni
as it transits through the host stomach.
Identification of
Campylobacter jejuni
Genes Contributing to Acid Adaptation by Transcriptional Profiling and Genome-Wide Mutagenesis
Authors: Reid Anne N. , Pandey Reenu , Palyada Kiran , Whitworth Lisa , Doukhanine Evgueni , Stintzi Alain
Published: January 2008

In order to cause disease, the food- and waterborne pathogen
Campylobacter jejuni
must face the extreme acidity of the host stomach as well as cope with pH fluctuations in the intestine. In the present study,
C. jejuni
NCTC 11168 was grown under mildly acidic conditions mimicking those encountered in the intestine. The resulting transcriptional profiles revealed how this bacterium fine-tunes gene expression in response to acid stress. This adaptation involves the differential expression of respiratory pathways, the induction of genes for phosphate transport, and the repression of energy generation and intermediary metabolism genes. We also generated and screened a transposon-based mutant library to identify genes required for wild-type levels of growth under mildly acidic conditions. This screen highlighted the important role played by cell surface components (flagella, the outer membrane, capsular polysaccharides, and lipooligosaccharides) in the acid stress response of
C. jejuni
. Our data also revealed that a limited correlation exists between genes required for growth under acidic conditions and genes differentially expressed in response to acid. To gain a comprehensive picture of the acid stress response of
C. jejuni
, we merged transcriptional profiles obtained from acid-adapted cells and cells subjected to acid shock. Genes encoding the transcriptional regulator PerR and putative oxidoreductase subunits Cj0414 and Cj0415 were among the few up-regulated under both acid stress conditions. As a Cj0415 mutant was acid sensitive, it is likely that these genes are crucial to the acid stress response of
C. jejuni
and consequently are important for host colonization.
Sexual Reproduction as the Cause of Heat Resistance in the Food Spoilage Fungus
Byssochlamys spectabilis
(Anamorph
Paecilomyces variotii
)
Authors: Houbraken Jos , Varga János , Rico-Munoz Emilia , Johnson Shawn , Samson Robert A.
Published: January 2008

Paecilomyces variotii
is a common cosmopolitan species that is able to spoil various food- and feedstuffs and is frequently encountered in heat-treated products. However, isolates from heat-treated products rarely form ascospores. In this study we examined by using molecular techniques and mating tests whether this species can undergo a sexual cycle and form ascospores. The population structure of this species was examined by analyzing the nuclear ribosomal internal transcribed spacer 1 (ITS1) and ITS2 and the 5.8S rRNA gene, as well as partial β-tubulin, actin, and calmodulin gene sequences. Phylogenetic analyses revealed that
P. variotii
is a highly variable species. Partition homogeneity tests revealed that
P. variotii
has a recombining population structure. In addition to sequence analyses, mating experiments indicated that
P. variotii
is able to form ascomata and ascospores in culture in a heterothallic manner. The distribution of MAT1-1 and MAT1-2 genes showed a 1:1 ratio in the progeny of the mating experiments. From the sequence analyses and mating data we conclude that
P. variotii
is the anamorph of
Talaromyces spectabilis
and that it has a biallelic heterothallic mating system. Since
Paecilomyces
sensu stricto anamorphs group within
Byssochlamys
, a new combination
Byssochlamys spectabilis
is proposed.
Water Deficit as a Driver of the Mutualistic Relationship between the Fungus
Trichoderma harzianum
and Two Wheat Genotypes
Authors: Donoso Eduardo P. , Bustamante Ramiro O. , Carú Margarita , Niemeyer Hermann M.
Published: January 2008

The aim of this study was to assess the occurrence of mutualistic interactions between the fungus
Trichoderma harzianum
and two wheat genotypes,
Triticum aestivum
cv. Talhuén and
T. turgidum
subsp.
durum
cv. Alifén, and the extent to which water deficit affected these interactions. Two wheat genotypes were cultivated in the presence or absence of
T. harzianum
and in the presence or absence of water deficit.
T. harzianum
was in turn cultivated in the presence or absence of wheat plants and in the presence or absence of water deficit. To evaluate the plant-fungus interactions, the root volume, dry biomass, and fecundity of wheat were determined, as was the population growth rate of the fungus.
Trichoderma harzianum
exerted a positive effect only on plants subjected to water deficit. The population growth rate of
T. harzianum
was negative in the absence of wheat plants and reached its highest level in the presence of plants under conditions of water deficit. These results confirm the occurrence of a mutualistic interaction between wheat and
T. harzianum
and show that it is asymmetric and context dependent.
Isolation and Characterization of Human Intestinal Bacteria Capable of Transforming the Dietary Carcinogen 2-Amino-1-Methyl-6-Phenylimidazo[4,5-
b
]Pyridine
Authors: Vanhaecke Lynn , Vercruysse Filip , Boon Nico , Verstraete Willy , Cleenwerck Ilse , De Wachter Marjan , De Vos Paul , van de Wiele Tom
Published: January 2008

2-Amino-1-methyl-6-phenylimidazo[4,5-
b
]pyridine (PhIP) is a carcinogenic heterocyclic aromatic amine formed in meat products during cooking. Although the formation of hazardous PhIP metabolites by mammalian enzymes has been extensively reported, research on the putative involvement of the human intestinal microbiota in PhIP metabolism remains scarce. In this study, the in vitro conversion of PhIP into its microbial derivate, 7-hydroxy-5-methyl-3-phenyl-6,7,8,9-tetrahydropyrido[3′,2′:4,5]imidazo[1,2-
a
]pyrimidin-5-ium chloride (PhIP-M1), by fecal samples from 18 human volunteers was investigated. High-performance liquid chromatography analysis showed that all human fecal samples transformed PhIP but with efficiencies ranging from 1.8 to 96% after 72 h of incubation. Two PhIP-transforming strains, PhIP-M1-a and PhIP-M1-b, were isolated from human feces and identified by fluorescent amplified fragment length polymorphism and
pheS
sequence analyses as
Enterococcus faecium
strains. Some strains from culture collections belonging to the species
E. durans
,
E. avium
,
E. faecium
, and
Lactobacillus reuteri
were also able to perform this transformation. Yeast extract, special peptone, and meat extract supported PhIP transformation by the enriched
E. faecium
strains, while tryptone, monomeric sugars, starch, and cellulose did not. Glycerol was identified as a fecal matrix constituent required for PhIP transformation. Abiotic synthesis of PhIP-M1 and quantification of the glycerol metabolite 3-hydroxypropionaldehyde (3-HPA) confirmed that the anaerobic fermentation of glycerol via 3-HPA is the critical bacterial transformation process responsible for the formation of PhIP-M1. Whether it is a detoxification is still a matter of debate, since PhIP-M1 has been shown to be cytotoxic toward Caco-2 cells but is not mutagenic in the Ames assay.
NADH Availability Limits Asymmetric Biocatalytic Epoxidation in a Growing Recombinant
Escherichia coli
Strain
Authors: Bühler Bruno , Park Jin-Byung , Blank Lars M. , Schmid Andreas
Published: January 2008

Styrene can efficiently be oxidized to (
S
)-styrene oxide by recombinant
Escherichia coli
expressing the styrene monooxygenase genes
styAB
from
Pseudomonas
sp. strain VLB120. Targeting microbial physiology during whole-cell redox biocatalysis, we investigated the interdependency of styrene epoxidation, growth, and carbon metabolism on the basis of mass balances obtained from continuous two-liquid-phase cultures. Full induction of
styAB
expression led to growth inhibition, which could be attenuated by reducing expression levels. Operation at subtoxic substrate and product concentrations and variation of the epoxidation rate via the styrene feed concentration allowed a detailed analysis of carbon metabolism and bioconversion kinetics. Fine-tuned
styAB
expression and increasing specific epoxidation rates resulted in decreasing biomass yields, increasing specific rates for glucose uptake and the tricarboxylic acid (TCA) cycle, and finally saturation of the TCA cycle and acetate formation. Interestingly, the biocatalysis-related NAD(P)H consumption was 3.2 to 3.7 times higher than expected from the epoxidation stoichiometry. Possible reasons include uncoupling of styrene epoxidation and NADH oxidation and increased maintenance requirements during redox biocatalysis. At epoxidation rates of above 21 μmol per min per g cells (dry weight), the absence of limitations by O
2
and styrene and stagnating NAD(P)H regeneration rates indicated that NADH availability limited styrene epoxidation. During glucose-limited growth, oxygenase catalysis might induce regulatory stress responses, which attenuate excessive glucose catabolism and thus limit NADH regeneration. Optimizing metabolic and/or regulatory networks for efficient redox biocatalysis instead of growth (yield) is likely to be the key for maintaining high oxygenase activities in recombinant
E. coli
.
Vanadium Requirements and Uptake Kinetics in the Dinitrogen-Fixing Bacterium
Azotobacter vinelandii
Authors: Bellenger J. P. , Wichard T. , Kraepiel A. M. L.
Published: January 2008

Vanadium is a cofactor in the alternative V-nitrogenase that is expressed by some N
2
-fixing bacteria when Mo is not available. We investigated the V requirements, the kinetics of V uptake, and the production of catechol compounds across a range of concentrations of vanadium in diazotrophic cultures of the soil bacterium
Azotobacter vinelandii
. In strain CA11.70, a mutant that expresses only the V-nitrogenase, V concentrations in the medium between 10
−8
and 10
−6
M sustain maximum growth rates; they are limiting below this range and toxic above.
A. vinelandii
excretes in its growth medium micromolar concentrations of the catechol siderophores azotochelin and protochelin, which bind the vanadate oxoanion. The production of catechols increases when V concentrations become toxic. Short-term uptake experiments with the radioactive isotope
49
V show that bacteria take up the V-catechol complexes through a regulated transport system(s), which shuts down at high V concentrations. The modulation of the excretion of catechols and of the uptake of the V-catechol complexes allows
A. vinelandii
to precisely manage its V homeostasis over a range of V concentrations, from limiting to toxic.
Molecular Structure and Transferability of Tn
1546
-Like Elements in
Enterococcus faecium
Isolates from Clinical, Sewage, and Surface Water Samples in Iran
Authors: Talebi M. , Pourshafie M. R. , Katouli M. , Möllby R.
Published: January 2008

The molecular structure and transferability of Tn
1546
in 143 vancomycin-resistant
Enterococcus faecium
(VREF) isolates obtained from patients (
n
= 49), surface water (
n
= 28), and urban and hospital sewage (
n
= 66) in Tehran, Iran, were investigated. Molecular characterization of Tn
1546
elements in
vanA
VREF was performed using a combination of restriction fragment length polymorphism analysis and DNA sequencing of the internal PCR fragments of
vanA
transposons. Long-PCR amplification showed that the molecular size of Tn
1546
elements varied from 10.8 to 12.8 kb. The molecular analysis of Tn
1546
showed that 45 isolates (31.5%) harbored a deletion/mutation upstream from nucleotide 170. No horizontal transfer of Tn
1546
was observed following filter-mating conjugation with these isolates. Nevertheless, the rates of transferability for other isolates were 10
−5
to 10
−6
per donor. Insertion sequences IS
1216V
and IS
1542
were present in 103 (72%) and 138 (96.5%) of the isolates, respectively. The molecular analysis of Tn
1546
elements resulted in three genomic organizations. The genomic organization lineage 1 was dominated by the isolates from clinical samples (3.4%), lineage 2 was dominated mostly by sewage isolates (24.5%), and lineage 3 contained isolates obtained from all sources (72.1%). The genetic diversity determined using pulsed-field gel electrophoresis (PFGE) revealed a single
E. faecium
clone, designated 44, which was common to the samples obtained from clinical specimens and hospital and municipal sewage. Furthermore, the results suggest that lineage 3 Tn
1546
was highly disseminated among our enterococcal isolates in different PFGE patterns.
Role of
Campylobacter jejuni
Respiratory Oxidases and Reductases in Host Colonization
Authors: Weingarten Rebecca A. , Grimes Jesse L. , Olson Jonathan W.
Published: January 2008

Campylobacter jejuni
is the leading cause of human food-borne bacterial gastroenteritis. The
C. jejuni
genome sequence predicts a branched electron transport chain capable of utilizing multiple electron acceptors. Mutants were constructed by disrupting the coding regions of the respiratory enzymes nitrate reductase (
napA
::Cm), nitrite reductase (
nrfA
::Cm), dimethyl sulfoxide, and trimethylamine
N
-oxide reductase (termed Cj0264::Cm) and the two terminal oxidases, a cyanide-insensitive oxidase (
cydA
::Cm) and
cbb3
-type oxidase (
ccoN
::Cm). Each strain was characterized for the loss of the associated enzymatic function in vitro. The strains were then inoculated into 1-week-old chicks, and the cecal contents were assayed for the presence of
C. jejuni
2 weeks postinoculation.
cydA
::Cm and Cj0264c::Cm strains colonized as well as the wild type;
napA
::Cm and
nrfA
::Cm strains colonized at levels significantly lower than the wild type. The
ccoN
::Cm strain was unable to colonize the chicken; no colonies were recovered at the end of the experiment. While there appears to be a role for anaerobic respiration in host colonization, oxygen is the most important respiratory acceptor for
C. jejuni
in the chicken cecum.
Heavy-Metal and Benzalkonium Chloride Resistance of
Listeria monocytogenes
Isolates from the Environment of Turkey-Processing Plants
Authors: Mullapudi S. , Siletzky R. M. , Kathariou S.
Published: January 2008

The resistance of
Listeria monocytogenes
to cadmium and arsenic has been used extensively for strain subtyping. However, limited information is available on the prevalence of such resistance among isolates from the environment of food-processing plants. In addition, it is not known whether the resistance of such isolates to heavy metals may correlate with resistance to quaternary ammonium compounds extensively used as disinfectants in the food-processing industry. In this study, we characterized 192
L. monocytogenes
isolates (123 putative strains) from the environment of turkey-processing plants in the United States for resistance to cadmium and arsenic and to the quaternary ammonium disinfectant benzalkonium chloride (BC). Resistance to cadmium was significantly more prevalent among strains of serotypes 1/2a (or 3a) and 1/2b (or 3b) (83% and 74%, respectively) than among strains of the serotype 4b complex (19%). Resistance to BC was encountered among 60% and 51% of the serotype 1/2a (or 3a) and 1/2b (or 3b) strains, respectively, and among 7% of the strains of the serotype 4b complex. All BC-resistant strains were also resistant to cadmium, although the reverse was not always the case. In contrast, no correlation was found between BC resistance and resistance to arsenic, which overall was low (6%). Our findings suggest that the processing environment of turkey-processing plants may constitute a reservoir for
L. monocytogenes
harboring resistance to cadmium and to BC and raise the possibility of common genetic elements or mechanisms mediating resistance to quaternary ammonium disinfectants and to cadmium in
L. monocytogenes
.