bluuebunny/crossref_metadata_2025 huggingface dataset:
Paradise lost: how marine science failed the world's coral reefs
Authors: Risk Michael J.
Published: March 2005

The response of the coral reef scientific community to the present global
crisis in coral reefs is here compared with response times and response
patterns of scientists in two previous international environmental crises:
eutrophication of the Great Lakes and acid rain in the Northen Hemisphere. In
both these previous crises, less than a decade passed from first appreciation
of the problem to development of identification/evaluation/mitigation
frameworks that were useful in a policy context. Key elements were avoidance
of arguments over methods, genuinely multidisciplinary teams, and the presence
of respected, technically trained managers. By contrast, twenty years after
identification of the major stresses on reefs and description of the major
monitoring strategies, there is no process–response model in place, in
any country, equivalent to those produced in response to eutrophication of the
Great Lakes or acid rain. Reasons for this failure include, but are not
limited to: dominance by one field of science, biology; lack of competent
scientific managers; and emphasis on monitoring programmes, with no clear idea
how the results will be used.
Biology, fishery and management of sardines (Sardinops sagax) in southern African waters
Authors: Beckley L. E. , van der Lingen C. D.
Published: March 2005

Sardines have been a major contributor to the pelagic fishery off southern
Africa for several decades. The South African and Namibian stocks are
separate, and seasonal hydrology, in conjunction with age-related behaviour,
produces the observed size-distribution patterns. Sardines are relatively
fast- growing and spawn repeatedly over the spring and summer months. Eggs and
larvae are transported from the Agulhas Bank to the west coast by the
north-flowing jet current at the shelf edge. Sardines are omnivorous,
microphagist filter-feeders and are important prey for many piscivorous
fishes, birds and mammals. There have been major fluctuations in sardine
population biomass in southern Africa which have been associated with
environment, regime shifts, recruitment and fishing. South African and
Namibian sardine catches peaked in the 1960s, declining dramatically
thereafter, and the pelagic fishing industry switched to anchovy. During the
1990s, sardine biomass increased but, although South African catches rose, the
Namibian stock collapsed again. The annual South African total allowable catch
is set through an operational management procedure that takes into account
biomass estimates from comprehensive hydroacoustic surveys and the sardine
by-catch in the anchovy fishery.
Australasian research on marine natural products: chemistry, bioactivity and ecology
Authors: Volkman John K.
Published: March 2005

An overview of recent research on marine natural products by Australian and
New Zealand scientists is presented. The review is not intended to be
encyclopaedic, but rather illustrative of the great variety of research at
present being carried out. Information is provided about the main research
groups and their research activities. Recent findings on the natural products
in marine microalgae, macroalgae, microorganisms, ascidians, bryozoans, corals
and sponges are summarized. More detailed information on some specific topics
is provided: these include unusual marine lipids, fish oils, chemical
inhibitors of marine biofouling, natural sunscreens, and coral sperm
attractants.
Australia’s marine science and technology plan: an action plan for Australia’s Oceans Policy
Authors: Reichelt R. E. , McEwan A. D.
Published: March 2005

Australia’s Oceans Policy (AOP) is a new Commonwealth (Federal)
government policy with sweeping implications for the management of the growing
and diverse marine sectors dependent on the nation’s vast marine
territory. Its theme of responsible use and protection in the context of
ecologically sustainable development provides an overarching and common
framework with interfaces between federal and State governments at all levels
while accommodating a host of pre-existing governmental regimes and
jurisdictions and international treaty obligations. Primary vehicles for the
implementation of the Policy will be ‘Regional Marine Plans’. The
accompanying Marine Science and Technology Plan is intended as the basis for
federal actions, such as priority setting for the government’s
scientific and technical capacities, to help implement the AOP. Three
programmes and 28 separate objectives are defined which detail specific needs
in various sectoral or scientific areas.
Science and technology will play a critical role in the implementation of the
AOP. Rather than being seen as a service resource for the execution of
user-driven AOP requirements, Australian scientific and technological
knowledge, expertise and infrastructure and their strategic enhancement should
be recognized collectively as a key component of the AOP itself and supported
for their cumulative benefit in fulfilling the objectives of the Policy.
Recent advances in HPLC pigment analysis of phytoplankton
Authors: Jeffrey S. W. , Wright S. W. , Zapata M.
Published: March 2005

Analysis of phytoplankton pigments is central to studies of marine ecology and
climate research. This paper summarizes milestones in the development of
methods of pigment analysis, and shows the use of HPLC technology in their
verification. New advances in HPLC methods are discussed, with key
developments being the use of polymeric C18 and
monomeric C8 columns and pyridine as solvent modifier.
These have allowed the resolution of divinyl chlorophylls
a and b, and the discovery of new
chlorophyll c pigments (both polar and non-polar) and
new 4-keto fucoxanthin derivatives. The taxonomic value of pigments and
pigment suites is examined. Methods of interpreting the percentage of algal
types from field measurements of pigment ratios through the use of computer
algorithms are discussed. Finally, prospects for future development are
suggested.
Comparison of the biogeochemistry of lakes and estuaries: ecosystem processes, functional groups, hysteresis effects and interactions between macro- and microbiology
Authors: Harris Graham P.
Published: March 2005

This paper reviews the biogeochemistry of carbon, nitrogen, phosphorus and
their associated minor elements (iron and sulfur) in rivers, lakes and
estuaries. The biogeochemistry of these elements can be explained by the
physiology and stoichiometry of the major functional groups of micro- and
macro-biota in these ecosystems. Furthermore, the global patterns of nitrogen
and phosphorus limitation in freshwater and marine systems are explicable in
terms of evolutionary differences between the major functional groups in
freshwater and marine ecosystems, and their physiology and stoichiometry, as
well as the interactions of carbon, iron, water residence times and ionic
strength as the water flows from catchments to the sea. The highly non-linear
responses of aquatic ecosystems to changing catchment loads of major and minor
elements are explained by the interactions of the major functional groups and
by competition between the pelagic and the benthos for nutrients and light.
Sources, sinks and transformations of organic carbon in Australian floodplain rivers
Authors: Robertson A. I. , Bunn S. E. , Boon P. I. , Walker K. F.
Published: March 2005

This paper reviews research on fluxes of carbon in Australian floodplain
rivers. Except where cover is absent, and in-stream gross primary production
is >1 gC m–2 day–1
and ratios of production to respiration are >1, riparian sources dominate
carbon pools in catchment streams. On floodplains, primary production by river
red gum (Eucalyptus camaldulensis) forests is ~600
gC m–2 year–1. Total
primary production by aquatic macrophytes and biofilms in floodplain wetlands
is >2500 gC m–2
year–1 and >620 gC
m–2 year–1,
respectively. Large pools of particulate organic carbon (POC) exist on
floodplains as litter (>500 gC m–2) and coarse
woody debris (~6 kgC m–2). Floods may release
50 gDOC m–2 from leaf litter. Export of this DOC
(dissolved organic carbon) may be substantial relative to autochthonous
production in river channels. Sediments deposited on floodplains during large
floods represent a substantial sink of riverine POC (up to 280 gC
m–2). Bacteria are responsible for rapid
decomposition of DOC and POC in floodplain wetlands (sediment respiration and
methanogenesis, both ~1 gC m–2
day–1). Flow and its interaction with
geomorphology control carbon fluxes in rivers. Decreased inputs of floodplain
carbon, following river regulation and physical disturbances to catchments and
floodplains, may have resulted in many Australian rivers being dominated by
algal production.
Global and local threats to coral reef functioning and existence: review and predictions
Authors: Wilkinson Clive R.
Published: March 2005

Factors causing global degradation of coral reefs are examined briefly as a
basis for predicting the likely consequences of increases in these factors.
The earlier consensus was that widespread but localized damage from natural
factors such as storms, and direct anthropogenic effects such as increased
sedimentation, pollution and exploitation, posed the largest immediate threat
to coral reefs. Now truly global factors associated with accelerating Global
Climate Change are either damaging coral reefs or have the potential to
inflict greater damage in the immediate future: e.g. increases in coral
bleaching and mortality, and reductions in coral calcification due to changes
in sea-water chemistry with increasing carbon dioxide concentrations. Rises in
sea level will probably disrupt human communities and their cultures by making
coral cays uninhabitable, whereas coral reefs will sustain minimal damage from
the rise in sea level. The short-term (decades) prognosis is indeed grim, with
major reductions almost certain in the extent and biodiversity of coral reefs,
and severe disruptions to cultures and economies dependent on reef resources.
The long-term (centuries to millennia) prognosis is more encouraging because
coral reefs have remarkable resilience to severe disruption and will probably
show this resilience in the future when climate changes either stabilize or
reverse.
Identification of transcribed sequences in
Arabidopsis thaliana
by using high-resolution genome tiling arrays
Authors: Stolc Viktor , Samanta Manoj Pratim , Tongprasit Waraporn , Sethi Himanshu , Liang Shoudan , Nelson David C. , Hegeman Adrian , Nelson Clark , Rancour David , Bednarek Sebastian , Ulrich Eldon L. , Zhao Qin , Wrobel Russell L. , Newman Craig S. , Fox Brian G. , Phillips George N. , Markley John L. , Sussman Michael R.
Published: March 2005

Using a maskless photolithography method, we produced DNA oligonucleotide microarrays with probe sequences tiled throughout the genome of the plant
Arabidopsis thaliana
. RNA expression was determined for the complete nuclear, mitochondrial, and chloroplast genomes by tiling 5 million 36-mer probes. These probes were hybridized to labeled mRNA isolated from liquid grown T87 cells, an undifferentiated
Arabidopsis
cell culture line. Transcripts were detected from at least 60% of the nearly 26,330 annotated genes, which included 151 predicted genes that were not identified previously by a similar genome-wide hybridization study on four different cell lines. In comparison with previously published results with 25-mer tiling arrays produced by chromium masking-based photolithography technique, 36-mer oligonucleotide probes were found to be more useful in identifying intron–exon boundaries. Using two-dimensional HPLC tandem mass spectrometry, a small-scale proteomic analysis was performed with the same cells. A large amount of strongly hybridizing RNA was found in regions “antisense” to known genes. Similarity of antisense activities between the 25-mer and 36-mer data sets suggests that it is a reproducible and inherent property of the experiments. Transcription activities were also detected for many of the intergenic regions and the small RNAs, including tRNA, small nuclear RNA, small nucleolar RNA, and microRNA. Expression of tRNAs correlates with genome-wide amino acid usage.
Cross GTPase-activating protein (CrossGAP)/Vilse links the Roundabout receptor to Rac to regulate midline repulsion
Authors: Hu Hailan , Li Ming , Labrador Juan-Pablo , McEwen Jason , Lai Eric C. , Goodman Corey S. , Bashaw Greg J.
Published: March 2005

The regulators of the Rho-family GTPases, GTPase-activating proteins (GAPs) and guanine exchange factors (GEFs), play important roles in axon guidance. By means of a functional genomic study of the Rho-family GEFs and GAPs inDrosophila, we have identified a Rho-family GAP, CrossGAP (CrGAP), which is involved in Roundabout (Robo) receptor-mediated repulsive axon guidance. CrGAP physically associates with the Robo receptor. Too much or too little CrGAP activity leads to defects in Robo-mediated repulsion at the midline choice point. The CrGAP gain-of-function phenotype mimics the loss-of-function phenotypes of both Robo and Rac. Dosage-sensitive genetic interactions among CrGAP, Robo, and Rac support a model in which CrGAP transduces signals downstream of Robo receptor to regulate Rac-dependent cytoskeletal changes.
Effects of titanium particle size on osteoblast functions
in vitro
and
in vivo
Authors: Choi Moon G. , Koh Hae S. , Kluess Daniel , O'Connor Daniel , Mathur Anshu , Truskey George A. , Rubin Janet , Zhou David X. F. , Sung K.-L. Paul
Published: March 2005

The formation of titanium (Ti)-wear particles during the lifetime of an implant is believed to be a major component of loosening due to debris-induced changes in bone cell function. Radiographic evidence indicates a loss of fixation at the implant–bone interface, and we believe that the accumulation of Ti particles may act on the bone-remodeling process and impact both long- and short-term implant-fixation strengths. To determine the effects of various sizes of the Ti particles on osteoblast function
in vivo
, we measured the loss of integration strength around Ti-pin implants inserted into a rat tibia in conjunction with Ti particles from one of four size-groups. Implant integration is mediated primarily by osteoblast adhesion/focal contact pattern, viability, proliferation and differentiation, and osteoclast recruitment at the implant site
in vivo
. This study demonstrates the significant attenuation of osteoblast function concurrent with increased expression of receptor activator of nuclear factor κB ligand (RANKL), a dominant signal for osteoclast recruitment, which is regulated differentially, depending on the size of the Ti particle. Zymography studies have also demonstrated increased activities of matrix metalloproteinases (MMP) 2 and 9 in cells exposed to larger Ti particles. In summary, all particles have adverse effects on osteoblast function, resulting in decreased bone formation and integration, but different mechanisms are elicited by particles of different sizes.
Tbx2b
is essential for neuronal differentiation along the dorsal/ventral axis of the zebrafish retina
Authors: Gross Jeffrey M. , Dowling John E.
Published: March 2005

The mechanisms by which retinal neurons are patterned along the dorsal/ventral axis remain largely unknown, yet this patterning is integral for the topographic mapping of visual space. With an interest in elucidating the mechanisms that regulate the development of this retinal axis, we have characterized a T-box family transcription factor,
Tbx2b
, during zebrafish retinogenesis.
Tbx2b
is expressed throughout all phases of retinal development with a striking asymmetry of distribution highest dorsally to lowest ventrally. To examine
Tbx2b
function during retinal development, two morpholino antisense oligonucleotides were created; one blocking the translational start site of
Tbx2b
and the other interfering with
Tbx2b
mRNA splicing. Injection of either of these morpholinos resulted in profound defects in the development of the dorsal retina. By using molecular markers for neuronal subtypes, the ventral retina contained all cell types, whereas in the dorsal retina, only retinal ganglion cells expressed markers of differentiation. The cells of the dorsal retina were postmitotic, however, as demonstrated by a lack of BrdUrd incorporation during the normal periods of retinal differentiation. Markers for dorsal and ventral retinal compartments were also expressed normally in
Tbx2b
morphants. Combined, these observations suggest that the cellular mechanisms regulating neuronal differentiation within the retina are asymmetric about the dorsal/ventral axis and that Tbx2b mediates this process within the dorsal retina.
Increased Preference for Ethanol in the Infant Rat after Prenatal Ethanol Exposure, Expressed on Intake and Taste Reactivity Tests
Authors: Arias Carlos , Chotro M Gabriela
Published: March 2005

Background:

Previous studies have shown that prenatal exposure during gestational days 17 to 20 to low or moderate doses of ethanol (1 or 2 g/kg) increases alcohol intake in infant rats. Taking into account that higher consumption does not necessarily suggest a preference for alcohol, in the present study, the hedonic nature of the prenatal experience was analyzed further with the use of a taste reactivity test.

Method:

General activity, wall climbing, passive drips, paw licking, and mouthing in response to intraoral infusions of alcohol, water, and a sucrose‐quinine solution (which resembles alcohol taste in rats) were tested in 161 preweanling 14‐day‐old rat pups that were prenatally exposed to 0, 1, or 2 g/kg of alcohol during gestational days 17 to 20. Consumption of those substances was measured during the taste reactivity test and on postnatal day 15.

Results:

Pups that were prenatally exposed to both doses of ethanol displayed lower levels of general activity and wall climbing than controls in response to ethanol. Infant rats that were treated prenatally with both doses of ethanol showed higher intake of the drug and also more mouthing and paw licking in response to ethanol taste. Only pups that were exposed to the higher ethanol dose in utero generalized those responses to the sucrose‐quinine compound.

Conclusions:

These results seem to indicate that for the infant rat, the palatability of ethanol is enhanced after exposure to the drug during the last days of gestation.
Short‐Term Neuropsychological Recovery in Clients with Substance Use Disorders
Authors: Bates Marsha E. , Voelbel Gerald T. , Buckman Jennifer F. , Labouvie Erich W. , Barry Danielle
Published: March 2005

Background:

Cognitive impairments are frequently observed in clients who enter treatment programs for substance abuse. The potential for early recovery of cognitive abilities is suggested by previous research; however, the extent of improvement and risk factors that may help predict individual differences in rates of recovery remain unclear. This study is a 6‐week follow‐up and retest of an original sample of 197 men and women who had received a broad neuropsychological assessment at addiction treatment entry. The aim was to examine the potential clinical significance of changes in cognitive functioning and the extent to which differential recovery was predictable from client background information.

Methods:

Fifteen neuropsychological tests were readministered to 169 of 197 clients 6 weeks after treatment entry. Structural equation modeling was used to estimate separately the practice effects and recovery in four cognitive domains: executive function, memory, information processing speed, and verbal ability. Client background information included age, sex, education, substance use and consequences, psychopathology, medical problems, familial alcoholism history, and childhood behavior problems.

Results:

A four‐factor model of latent neuropsychological ability that was previously identified at treatment entry was replicated at follow‐up. Statistically significant increases in the means of the four latent abilities were found. Memory showed a medium effect size improvement. Executive function, verbal ability, and information processing speed, however, showed only small effect size improvements, suggesting limited clinical significance. Substance use between treatment entry and follow‐up, antisocial personality disorder, negative use consequences, less education, and medical problems were modestly predictive of less recovery.

Conclusion:

Cognitive recovery in the first 6 weeks of treatment is possible, but, with the possible exception of memory, improvement may be minor in terms of clinical relevance.
Alcohol Withdrawal and Conditioning
Authors: Little Hilary J. , Stephens David N. , Ripley Tamzon L. , Borlikova Gilyana , Duka Theodora , Schubert Manja , Albrecht Doris , Becker Howard C. , Lopez Marcello F. , Weiss Friedbert , Drummond Colin , Peoples Michelle , Cunningham Christopher
Published: March 2005

This review contains the proceedings from a symposium held at the RSA conference in 2003 on “Alcohol Withdrawal and Conditioning.” The presentations covered a range of interactions between conditioning and alcohol withdrawal, in both animal behavior and the clinic. Dr. D.N. Stephens first described his studies exploring the consequences of alcohol dependence and repeated experience of withdrawal on the conditioning process. His data suggested that repeated withdrawal from moderate alcohol intake impairs amygdala‐dependent mechanisms for learning about aversive events. Dr. H. Becker then detailed studies examining the consequences of repeated ethanol withdrawal experience on subsequent ethanol drinking behavior in mice, and conditions in which motivational properties of odor cues that are associated with different phases of ethanol withdrawal influence such relapse behavior. The data suggested that cues associated with acute withdrawal or “recovery” from withdrawal may serve as modulating factors in influencing subsequent ethanol drinking behavior, and that the timing of the cues determines their consequences. Dr. F. Weiss described recent findings from animal models of relapse that suggested the efficacy of alcohol‐associated contextual stimuli in eliciting alcohol‐seeking behavior resembles the endurance of conditioned cue reactivity and cue‐induced cocaine craving in humans. The interactive effects of stress and ethanol‐related environmental stimuli were found to be dependent on concurrent activation of endogenous opioid and corticotropin‐releasing factor systems. Conditioning factors (i.e., exposure to drug‐associated stimuli) and stress could therefore interact to augment vulnerability to relapse. Dr. C. Drummond then addressed the clinical aspects of conditioning during alcohol withdrawal and described studies showing exposure of alcoholics to alcohol‐related cues elicited greater subjective and physiological responses than exposure to neutral cues. The former responsivity showed a relationship with a measure of motivation to drink alcohol. Finally, Dr. C. Cunningham provided a summary of the concepts involved in the presentations and discussed the conditioning processes that affect behavior during and after alcohol withdrawal.
Comparison of 3D and 2D field‐circuit models of power transformer transients
Authors: Nowak Lech , Demenko Andrzej , Szeląg Wojciech
Published: March 2005

This paper deals with a coupled field‐circuit simulation of transients in a three‐phase, three‐limb power transformer taking non‐linearity into consideration. A comparative analysis of the results obtained from the application of 3D and 2D field models has been carried out. Owing to core saturation and the non‐periodic components of the magnetic fluxes, the magnetic field exists also within the space surrounding the core. Hence, three‐dimensional description is necessary. It has been proved that assuming the 2D model significantly overstated peak values of currents are obtained.
Formulation of mixed elements for the 2D‐BEM
Authors: Schimmanz Klaus , Kost Arnulf
Published: March 2005

Accuracy and time consumption in numerical computations are often in contradiction to each other. In modern industrial design processes flux field computation becomes more and more important. Thus, it is desirable to minimize any methodical error for better performance. This paper discusses a flaw of frequently used standard elements in boundary‐element‐method and shows a way to avoid it.
Coupled mechanical‐electrostatic FE‐BE analysis with FMM acceleration
Authors: Sabariego R.V. , Gyselinck J. , Dular P. , De Coster J. , Henrotte F. , Hameyer K.
Published: March 2005

This paper deals with the coupled mechanical‐electrostatic analysis of a shunt capacitive MEMS switch. The mechanical and electrostatic parts of the problem are modelled by the FE and BE methods, respectively. The fast multipole method is applied to reduce the storage requirements and the computational cost of the BE electrostatic model. An adaptive truncation expansion of the 3D Laplace Green function is employed. The strong interaction between the mechanical and electrostatic systems is considered iteratively.
Modelisation of thin cracks with varying conductivity in eddy‐current testing
Authors: Beltrame Ph.
Published: March 2005

In the ideal crack model (negligible thickness and an impenetrable barrier to electric current) in eddy‐current testing frame, the field‐flaw is equivalent to a current dipole layer on its surface. This dipole density is the solution of an integral equation with a hyperstrong kernel. This model has shown its efficiency, as well the computing accuracy, as for the CPU time. Furthermore, the case of a current leakage across crack was considered by introducing an equivalent conductivity of the crack. This paper aims at simulating a local varying conductivity. In particular, we focus on a constant piecewise conductivity. In this last case, because of the presence of the hypersingular kernel in the equation, the numerical scheme using the ideal case has to be modified.
Non‐nested geometric multigrid method using consistency error correction for discrete magnetic curl‐curl formulations
Authors: Clemens M. , Feigh S. , Wilke M. , Weiland T.
Published: March 2005

The simulation of magnetic fields with geometric discretization schemes using magnetic vector potentials involves the solution of very large discrete consistently singular curl‐curl systems of equations. Geometric and algebraic multigrid schemes for their solution require intergrid transfer operators of restriction and prolongation that achieve the discrete conservation of integral quantities serving as state‐variables of geometric discretization methods. For non‐conservative restriction operations, a consistency error correction operator related to an algebraic filtering is proposed. Numerical results show the effects of the consistency correction for a non‐nested geometric multigrid method.
The Newton‐Raphson method for solving non‐linear and anisotropic time‐harmonic problems
Authors: Vande Sande H. , Henrotte F. , Hameyer K.
Published: March 2005

This paper discusses the use of a complex‐valued reluctivity tensor for modelling non‐linear, anisotropic and hysteretic materials in a time‐harmonic finite element context. It is shown how these problems can be solved by the Newton‐Raphson method. The method is applied for the simulation of the magnetic field distribution in a three‐phase transformer.
The eggshell approach for the computation of electromagnetic forces in 2D and 3D
Authors: Henrotte François , Deliége Geoffrey , Hameyer Kay
Published: March 2005

The expressions of the material derivative of differential forms in the language of vector analysis are introduced. These formulae allow us to describe naturally the electromechanical coupling, and the coupling term appears to be a volume integral. A general approach to compute forces is then proposed, which takes that fact into consideration. The method is applicable in 2D and 3D with dual formulations. Numerical evidences of its efficiency are given.
Comparison of static, dynamic, and static‐dynamic eccentricity in induction machines with squirrel‐cage rotors using 2D‐transient FEM
Authors: Schlensok Christoph , Henneberger Gerhard
Published: March 2005

Finite‐element simulations of induction machines with squirrel‐cage rotor require transient solution algorithms. For this reason a transient 2D solver is utilized which takes rotational movement of the rotor into account. Its formulation and the time‐step algorithm are given. Two different kinds of eccentricity of the rotor and their combination are defined and studied. The three motor variants are computed and the torque, the net force, and the surface‐force density are compared in time and frequency domain.
Learning about being critical
Authors: Walsham Geoff
Published: March 2005

Abstract.This short paper is a response to the article by McGrath in this issue which argues that information systems (IS) researchers need to be more explicit about ‘being critical’. I accept her point, and I use this paper to offer a sketch of my personal journey in learning about criticality, and some thoughts from where I am now on various aspects of carrying out critical IS research.
Towards a model of consumer use of mobile information and communication technology in LDCs: the case of sub‐Saharan Africa
Authors: Meso Peter , Musa Philip , Mbarika Victor
Published: March 2005

Abstract. Using theories of technology acceptance and technology transfer, we identified factors affecting the use of mobile information and communication technology (mobile ICT) in the least developed countries (LDCs), specifically sub‐Saharan Africa. From a literature review, we developed a research model to describe factors that impact mobile ICT use and formulated a series of hypotheses about them. We then surveyed mobile ICT users in Kenya and Nigeria and created a structural model to examine our hypothesized relationships. Our findings indicate that access to mobile ICT, and cultural influences on mobile ICT diffusion, strongly influence individuals’ perceptions of the usefulness and ease of use of mobile ICT. Individuals’ perceptions about the reliability of mobile ICT influence use of these technologies significantly. The results suggest that, although extensive ICT diffusion (high mobile ICT levels per capita) may be necessary for seeding commercial and economic initiatives that depend heavily on mobile ICT, such as m‐commerce, it may not be sufficient. Firms conducting business in sub‐Saharan Africa need to pay attention to the factors that explain individual mobile ICT use because these factors will most likely determine the optimal market segmentation, business development and customer service strategies for leveraging m‐commerce operations in that region. For government units, the understanding of such factors would also be beneficial in aiding economic planning and commerce.
BvgA functions as both an activator and a repressor to control Bvgi phase expression of bipA in Bordetella pertussis
Authors: Williams Corinne L. , Boucher Philip E. , Stibitz Scott , Cotter Peggy A.
Published: March 2005

The Bordetella bipA gene is expressed maximally when the BvgAS phosphorelay is semi‐active, i.e. in the Bvg‐intermediate (Bvgi) phase. We used a BvgA‐FeBABE cleavage approach together with site‐directed mutagenesis and bipA–lacZ fusion analyses to determine precisely where BvgA‐phosphate (BvgA∼P) binds at the bipA promoter and how that binding contributes to the complex transcription pattern displayed by bipA. BvgA∼P bound with high affinity and cooperatively with RNAP to sequences at the bipA promoter immediately 5′ to and overlapping those bound by RNAP to activate transcription under Bvgi phase conditions. bipA therefore, like fhaB, appears to be similar to classical class‐II promoters with regard to the mechanism by which its transcription is activated. BvgA∼P bound with relatively low affinity to sequences immediately 3′ of those bound by RNAP at the bipA promoter and this binding mediated repression of bipA transcription under Bvg+ phase conditions. BvgA∼P binding to these sequences occurred simultaneously, if not cooperatively, with RNAP, indicating that BvgA∼P represses bipA expression by inhibiting transcription initiation and/or elongation, rather than by competing with RNAP for binding. As bipA is the first Bvgi phase gene to be characterized, and the first gene shown to be repressed by BvgA∼P directly, our results will provide a basis for comparison as additional Bvg‐regulated genes are identified and characterized.
The cell density‐dependent expression of stewartan exopolysaccharide in Pantoea stewartii ssp. stewartii is a function of EsaR‐mediated repression of the rcsA gene
Authors: Minogue Timothy D. , Carlier Aurelien L. , Koutsoudis Maria D. , Von Bodman Susanne B.
Published: March 2005

The LuxR‐type quorum‐sensing transcription factor EsaR functions as a repressor of exopolysaccharide (EPS) synthesis in the phytopathogenic bacterium Pantoea stewartii ssp. stewartii. The cell density‐dependent expression of EPS is critical for Stewart's wilt disease development. Strains deficient in the synthesis of a diffusible acyl‐homoserine lactone inducer remain repressed for EPS synthesis and are consequently avirulent. In contrast, disruption of the esaR gene leads to hypermucoidy and attenuated disease development. Ligand‐free EsaR functions as a negative autoregulator of the esaR gene and responds to exogenous acyl‐homoserine lactone for derepression. The focus of this study was to define the mechanism by which EsaR governs the expression of the cps locus, which encodes functions required for stewartan EPS synthesis and membrane translocation. Genetic and biochemical studies show that EsaR directly represses the transcription of the rcsA gene. RcsA encodes an essential coactivator for RcsA/RcsB‐mediated transcriptional activation of cps genes. In vitro assays identify an EsaR DNA binding site within the rcsA promoter that is reasonably well conserved with the previously described esaR box. We also describe that RcsA positively controls its own expression. Interestingly, promoter proximal genes within the cps cluster are significantly more acyl‐homoserine lactone responsive than genes located towards the middle or 3′ end of the gene cluster. We will discuss a possible role of EsaR‐mediated quorum sensing in the differential expression of the cps operon.
Evidence that Bacillus catabolite control protein CcpA interacts with RNA polymerase to inhibit transcription
Authors: Kim Jeong‐Ho , Yang Young‐Ki , Chambliss Glenn H.
Published: March 2005

Bacillus
catabolite control protein (CcpA) mediates carbon catabolite repression (CCR) by controlling expression of catabolite responsive (CR) genes or operons through interaction with catabolite responsive elements (cres) located within or outside of CR promoters. Here, we investigated how CcpA inhibits the transcription of CR promoters in vitro. CcpA has different affinities for different cres, but this does not correlate with its ability to inhibit transcription. In the amyE promoter, which overlaps a CcpA binding site (amyE cre centred at +4.5), CcpA does not prevent RNA polymerase (RNAP) binding to the promoter; it may even interact with RNAP. Inserting non‐integral turns of helix (1.5 and 2.5) between the amyE promoter (−10 hexamer) and the amyE cre relieved CCR of amyE expression. In the xyl operon, despite the downstream location of its cre (a major cre centred at +130.5), CcpA blocked transcription initiation, not  elongation  (roadblock) at the site of the cre. Taken together, our results strongly suggest that CcpA requires interactions with RNAP to inhibit transcription.
The Campylobacter jejuni stringent response controls specific stress survival and virulence‐associated phenotypes
Authors: Gaynor Erin C. , Wells Derek H. , MacKichan Joanna K. , Falkow Stanley
Published: March 2005

Campylobacter jejuni is a highly prevalent food‐borne pathogen that causes diarrhoeal disease in humans. A natural zoonotic, it must overcome significant stresses both in vivo and during transmission despite the absence of several traditional stress response genes. Although relatively little is understood about its mechanisms of pathogenesis, its ability to interact with and invade human intestinal epithelial cells closely correlates with virulence. A C. jejuni microarray‐based screen revealed that several known virulence genes and several uncharacterized genes, including spoT, were rapidly upregulated during infection of human epithelial cells. spoT and its homologue relA have been shown in other bacteria to regulate the stringent response, an important stress response that to date had not been demonstrated for C. jejuni or any other epsilon‐proteobacteria. We have found that C. jejuni mounts a stringent response that is regulated by spoT. Detailed analyses of a C. jejuniΔspoT mutant revealed that the stringent response is required for several specific stress, transmission and antibiotic resistance‐related phenotypes. These include stationary phase survival, growth and survival under low CO2/high O2 conditions, and rifampicin resistance. A secondary suppressor strain that specifically rescues the low CO2 growth defect of the ΔspoT mutant was also isolated. The stringent response additionally proved to be required for the virulence‐related phenotypes of adherence, invasion, and intracellular survival in two human epithelial cell culture models of infection; spoT is the first C. jejuni gene shown to participate in longer term survival in epithelial cells. Microarray analyses comparing wild‐type to the ΔspoT mutant also revealed a strong correlation between gene expression profiles and phenotype differences observed. Together, these data demonstrate a critical role for the C. jejuni stringent response in multiple aspects of C. jejuni biology and pathogenesis and, further, may lend novel insight into unexplored features of the stringent response in other prokaryotic organisms.
The apicoplast of Plasmodium falciparum is translationally active
Authors: Chaubey Sushma , Kumar Ambrish , Singh Divya , Habib Saman
Published: March 2005

Apicoplast, the plastid‐like organelle of apicomplexan parasites, has generated interest as a putative drug target. Although transcripts for genes encoded by the 35 kb circular plastid DNA have been detected, the actual presence of their protein products has only been postulated. We provide evidence for translation of the tufA gene encoded by the Plasmodium falciparum apicoplast genome. Translation elongation factor Tu (EF‐Tu), the product of tufA, was localized within the organelle. TufA was found to express maximally in the trophozoite stage of the intraerythrocytic cycle. Additionally, the drug thiostrepton that has a binding site in apicoplast LSU rRNA, reduced P. falciparum apicoplast EF‐Tu levels thus strengthening the view that translation in the apicoplast is the site of action of this drug.
IcmS‐dependent translocation of SdeA into macrophages by the Legionella pneumophila type IV secretion system
Authors: Bardill J. Patrick , Miller Jennifer L. , Vogel Joseph P.
Published: March 2005

Legionella pneumophila replicates inside alveolar macrophages and causes an acute, potentially fatal pneumonia called Legionnaires’ disease. The ability of this bacterium to grow inside of macrophages is dependent on the presence of a functional dot/icm type IV secretion system (T4SS). Proteins secreted by the Dot/Icm T4SS are presumed to alter the host endocytic pathway, allowing L. pneumophila to establish a replicative niche within the host cell. Here we show that a member of the SidE family of proteins interacts with IcmS and is required for full virulence in the protozoan host Acanthamoeba castellanii. Using immunofluorescence microscopy and adenylate cyclase fusions, we show that SdeA is secreted into host cells by L. pneumophila in an IcmS‐dependent manner. The SidE‐like proteins are secreted very early during macrophage infection, suggesting that they are important in the initial formation of the replicative phagosome. Secreted SidE family members show a similar localization to other Dot/Icm substrates, specifically, to the poles of the replicative phagosome. This common localization of secreted substrates of the Dot/Icm system may indicate the formation of a multiprotein complex on the cytoplasmic face of the replicative phagosome.
Fluffy, the major regulator of conidiation in Neurospora crassa, directly activates a developmentally regulated hydrophobin gene
Authors: Rerngsamran Panan , Murphy Michael B. , Doyle Sharon A. , Ebbole Daniel J.
Published: March 2005

The fluffy (fl) gene of Neurospora crassa is required for asexual sporulation and encodes an 88 kDa polypeptide containing a typical fungal Zn2Cys6 DNA‐binding motif. Identification of genes regulated by fl will provide insight into how fungi regulate growth during morphogenesis. As a step towards identifying the target genes on which FL may act, we sought to define target sequences to which the FL protein binds. The DNA binding domain of FL was expressed in Escherichia coli as a fusion with glutathione S‐transferase (GST) and purified using glutathione‐sepharose affinity chromatography. The DNA binding sites were selected and amplified by means of a polymerase chain reaction (PCR)‐mediated random‐site selection method involving affinity bead‐binding and gel mobility shift analysis. Sequencing and comparison of the selected clones suggested that FL binds to the motif 5′‐CGG(N)9CCG‐3′. A potential binding site was found in the promoter region of the eas (ccg‐2) gene, which encodes a fungal hydrophobin. In vitro competitive binding assays revealed a preferred binding site for FL in the eas promoter, 5′‐CGGAAGTTTC CTCCG‐3′, which is located 1498 bp upstream of the eas translation initiation codon. In vivo experiments using a foreign DNA sequence tag also confirmed that this sequence resides in a region required for FL regulation. In addition, yeast one hybrid experiments demonstrated that the C‐terminal portion of FL functions in transcriptional activation. Transcriptional profiling was used to identify additional potential targets for regulation by fl.
Four conserved intramolecular disulphide linkages are required for secretion and cell wall localization of a hydrophobin during fungal morphogenesis
Authors: Kershaw Michael J. , Thornton Christopher R. , Wakley Gavin E. , Talbot Nicholas J.
Published: March 2005

Hydrophobins are morphogenetic proteins produced by fungi during assembly of aerial hyphae, sporulation, mushroom development and pathogenesis. Eight cysteine residues are present in hydrophobins and form intramolecular disulphide bonds. Here, we show that expressing eight cysteine–alanine substitution alleles of theMPG1hydrophobin gene fromMagnaporthe griseacauses severe defects in development of aerial hyphae and spores. Immunolocalization revealed that Mpg1 hydrophobin variants, lacking intact disulphide bonds, retain the capacity to self‐assemble, but are not secreted to the cell surface. This provides the first genetic evidence that disulphide bridges in a hydrophobin are dispensable for aggregation, but essential for secretion.
A case of primary rectal mucosa‐associated lymphoid tissue lymphoma treated by endoscopic mucosal resection
Authors: Yamamoto Ryuichi , Kato Shingo , Shimazaki Kae , Yoshizumi Tsukasa , Uefuji Kazuhiko , Seo Mitsuru , Matsuura Takashi , Kikuchi Masahiro , Itoh Kazuro , Miura Soichiro
Published: March 2005

A 53‐year‐old man underwent surveillance colonoscopy that revealed a submucosal tumor‐like polypoid lesion on the Rb area of the rectum. Histological examination of biopsy specimens showed chronic inflammation. Endoscopic mucosal resection was performed after obtained informed consent for the purpose of obtaining accurate diagnosis and for curative treatment. Pathological findings of the resected specimen showed low‐grade B‐cell lymphoma of mucosa‐associated lymphoid tissue type (MALT lymphoma). Gallium‐scintigraphy, abdominal CT, small bowel series and endoscopic examination of the upper gastrointestinal tract revealed no abnormalities. Based on the findings, a diagnosis of stage IE lymphoma was made. However it was suspected that the vertical cut‐end of the resected specimen had residue of lymphoma cells. Additional transanal resection of the rectum was therefore performed, but no lymphoma cells were found in the specimen. Eradication of Helicobacter pylori was also performed. Although a standard therapeutic strategy for colonic MALT lymphoma has not been established, endoscopic mucosal resection might be a good therapeutic choice.
Evaluation of gastric emptying by electrogastrography and ultrasonography in gastroesophageal reflux disease
Authors: Kujime Sae , Inoue Syuji , Nomura Masahiro , Endo Jyunko , Uemura Nobutaka , Kishi Seiichiro , Nakaya Yutaka , Ito Susumu
Published: March 2005

Background: It has been suggested that transient lower esophageal sphincter relaxation is involved in the occurrence of gastroesophageal reflux disease (GERD) and that decreased gastric emptying is an exacerbating factor of transient LES relaxation. In addition, the gastric emptying function is considered to be closely related to gastric motility.

Methods: Gastric activity was evaluated by electrogastrography (EGG) in 22 patients with endoscopically positive reflux esophagitis (15 with mild esophagitis of Los Angeles grade A or B and seven with severe esophagitis of Los Angeles grade C or D) and 20 normal individuals. The gastric emptying function was also evaluated by abdominal ultrasonography. The sampling cycle of EGG was 1 s, and the measured frequency was 2.1–6.0 cycle/min (c.p.m.). The mean amplitude of EGG was compared by EGG spectral analysis among brady‐gastria cases with a contraction frequency of less than 2.4 c.p.m., normo‐gastria cases with a contraction frequency of 2.4–3.6 c.p.m., and tachy‐gastria cases with a contraction frequency exceeding 3.6 c.p.m.

Results: In the patients with GERD, both the frequency of 3‐c.p.m. waves and peak frequency were reduced, and the gastric emptying function examined by ultrasonography had deteriorated, in comparison with normal individuals. Of those with GERD, the ultrasonographic gastric emptying function was significantly reduced in all patients with severe esophagitis compared with those with mild esophagitis, but the differences of the frequency of 3‐c.p.m. waves, the peak frequency, were not significant. Also, no significant difference was observed in the frequency of 3‐c.p.m. waves or the ultrasonographic gastric emptying function between the 16 patients with hiatal hernia and the six patients with no hiatal hernia. However, the mean amplitude in brady‐gastria and tachy‐gastria was significantly increased in the patients with hiatal hernia compared to those without hiatal hernia.

Conclusions: Reduced gastric motility was suggested to be involved in the development of reflux esophagitis, and the presence of hiatal hernia was considered to have some effect on gastric motility.
Endoscopic snare excision for a major papilla tumor
Authors: Igarashi Yoshinori , Okano Naoki , Satou Daisuke , Itou Ken , Mimura Takahiko , Miura Tomihiro , Iida Kazunari , Sumino Yasukiyo , Miki Kazumasa
Published: March 2005

Tumors of the duodenal papilla include hyperplasia, adenoma, carcinoma in adenoma and carcinoma. As the duodenal papilla has special anatomical characteristics and treatment involves major intervention and correct preoperative diagnosis. In patients with adenoma, or early carcinoma of the papilla, various endoscopic snare excision techniques are indicated for complete removal the tumor. Pancreatitis and cholangitis are major complications caused by endoscopic techniques. In the present study, endoscopic snare excision of the tumor located at the major papilla was carried out in two cases with early carcinoma or adenoma patients using a therapeutic duodenoscope, a spiral snare for the colon, and pure cutting current. The patients who underwent insertion of a 5‐Fr pancreatic stent and a 7‐Fr biliary stent inserted immediately after endoscopic tumor resection did not develop either pancreatitis nor cholangitis. This seems to be a safe technical method to prevent complications of endoscopic snare excision of the major papilla tumor.