bluuebunny/crossref_metadata_2025 huggingface dataset:
Public health and economic costs of investigating a suspected outbreak of Legionnaires' disease
Authors: LOCK K. , MILLETT C. , HEATHCOCK R. , JOSEPH C. A. , HARRISON T. G. , LEE J. V. , RAO G. , SURMAN-LEE S. ,   on behalf of the Outbreak Control Team
Published: December 2007

This paper provides one of the first assessments of the burden of both the public health investigation and the economic costs associated with an apparent outbreak of Legionnaires' disease (LD) in South East London. In addition to epidemiological, microbiological and environmental investigations, we collected data on the staff time and resources committed by the 11 main organizations responsible for managing the outbreak. Of the overall estimated costs of £455 856, only 14% (£64 264) was spent on investigation and control of the outbreak compared with 86% (£391 592) spent on the hospital treatment of the patients. The time and money spent on public health services in this investigation appear to represent good value for money considering the potential costs of a major outbreak, including the high case-fatality rate in LD generally and the high health-care costs. Further research is needed to determine optimum strategies for the cost-effective use of health system resources in investigations of LD. Whether the threshold for investigation of cases should be based on observed incidence rates or the cost-effectiveness of investigations, or both, should be debated further.
Cerebral Blood Flow Heterogeneity in Preterm Sheep: Lack of Physiologic Support for Vascular Boundary Zones in Fetal Cerebral White Matter
Authors: McClure Melissa M , Riddle Art , Manese Mario , Luo Ning Ling , Rorvik Dawn A , Kelly Katherine A , Barlow Clyde H , Kelly Jeffrey J , Vinecore Kevin , Roberts Colin T , Hohimer A Roger , Back Stephen A
Published: December 2007

Periventricular white matter (PVWM) injury is the leading cause of neurologic disability in survivors of prematurity. To address the role of ischemia in PVWM and cerebral cortical injury, we hypothesized that immaturity of spatially distal vascular ‘end zones’ or ‘border zones’ predisposes PVWM to greater decreases in cerebral blood flow (CBF) than more proximal structures. We quantified regional CBF with fluorescently labeled microspheres in 0.65 gestation fetal sheep in histopathologically defined three-dimensional regions by post hoc digital dissection and coregistration algorithms. Basal flow in PVWM was significantly lower than in gyral white matter and cortex, but was equivalent in superficial, middle, and deep PVWM. Absolute and relative CBF (expressed as percentage of basal) did not differ significantly during ischemia or reperfusion between PVWM, gyral white matter, or cortex. Moreover, CBF during ischemia-reperfusion was equivalent in three adjacent PVWM levels and was not consistent with the magnitude of severity of PVWM injury, defined by TUNEL (terminal deoxynucleotidyltransferase-mediated dUPT nick end labeling) staining. However, the magnitude of ischemia was predicted by the severity of discrete cortical lesions. Hence, unlike cerebral cortex, unique CBF disturbances did not account for the distribution of PVWM injury. Previously defined cellular maturational factors, thus, appear to have a greater influence on PVWM vulnerability to ischemic injury than the presence of immature vascular boundary zones.
Multiple scaling replica exchange for the conformational sampling of biomolecules in explicit water
Authors: Kamberaj Hiqmet , van der Vaart Arjan
Published: December 2007

A multiple scaling replica exchange method for the efficient conformational sampling of biomolecular systems in explicit solvent is presented. The method is a combination of the replica exchange with solute tempering (REST) technique and a Tsallis biasing potential. The Tsallis biasing increases the sampling efficiency, while the REST minimizes the number of replicas needed. Unbiased statistics can be obtained by reweighting of the data using a weighted histogram analysis technique. The method is illustrated by its application to a ten residue peptide in explicit water.
Pulsed field gradient NMR study of phenol binding and exchange in dispersions of hollow polyelectrolyte capsules
Authors: Choudhury Rudra Prosad , Schönhoff Monika
Published: December 2007

The distribution and exchange dynamics of phenol molecules in colloidal dispersions of submicron hollow polymeric capsules is investigated by pulsed field gradient NMR (PFG-NMR). The capsules are prepared by layer-by-layer assembly of polyelectrolyte multilayers on silica particles, followed by dissolution of the silica core. In capsule dispersion, H1 PFG echo decays of phenol are single exponentials, implying fast exchange of phenol between a free site and a capsule-bound site. However, apparent diffusion coefficients extracted from the echo decays depend on the diffusion time, which is typically not the case for the fast exchange limit. We attribute this to a particular regime, where apparent diffusion coefficients are observed, which arise from the signal of free phenol only but are influenced by exchange with molecules bound to the capsule, which exhibit a very fast spin relaxation. Indeed, relaxation rates of phenol are strongly enhanced in the presence of capsules, indicating binding to the capsule wall rather than encapsulation in the interior. We present a quantitative analysis in terms of a combined diffusion-relaxation model, where exchange times can be determined from diffusion and spin relaxation experiments even in this particular regime, where the bound site acts as a relaxation sink. The result of the analysis yields exchange times between free phenol and phenol bound to the capsule wall, which are on the order of 30ms and thus slower than the diffusion controlled limit. From bound and free fractions an adsorption isotherm of phenol to the capsule wall is extracted. The binding mechanism and the exchange mechanism are discussed. The introduction of the global analysis of diffusion as well as relaxation echo decays presented here is of large relevance for adsorption dynamics in colloidal systems or other systems, where the standard diffusion echo decay analysis is complicated by rapidly relaxing boundary conditions.
Unsteady turbulent round jets and vortex motion
Authors: Abani Neerav , Reitz Rolf D.
Published: December 2007

A new model to predict the velocity distribution in round jets with time-varying injection profiles has been formulated as an extension of steady jet theory. The approach introduces an effective injection velocity within the jet based on a representative response time. It is assumed that the instantaneous injection velocity affects the velocity within the jet with an exponential response function and that the response time is related to the fluid particle’s residence time within the jet, consistent with the theory of translation of jet vortex rings from Helmholtz’s vortex motion analysis [P. G. Tait, London Edinburgh Dublin Philos. Mag. J. Sci. 33, 485 (1867)]. The Helmholtz theory is also shown to reduce to the well-known velocity decay rate in the case of steady turbulent gas jets. A Duhamel superposition integral is used to determine the effective injection velocity for time-varying injection rates. The model is tested with different injection profiles and different ambient densities. The results are also compared with numerical results from a computational fluid dynamics code. The comparisons agree very well and the new model is shown to offer an efficient method to predict jet tip penetrations for unsteady jets.
Epitaxial growth of ultrahigh density Ge1−xSnx quantum dots on Si (111) substrates by codeposition of Ge and Sn on ultrathin SiO2 films
Authors: Nakamura Yoshiaki , Masada Akiko , Cho Sung-Pyo , Tanaka Nobuo , Ichikawa Masakazu
Published: December 2007

A method to form epitaxial Ge1−xSnx quantum dots (QDs) on Si (111) substrates has been developed by codeposition of Ge and Sn on ultrathin SiO2 films with predeposited Ge nuclei. Hemispherical Ge1−xSnx QDs with an ultrahigh density (∼1012 cm−2) were epitaxially grown in the nanometer-size range. The QD size was controlled by changing the GeSn deposition amount. High-resolution transmission electron microscopy observations revealed that the main formed Ge1−xSnx QDs had less strain and no misfit dislocations.
Time-resolved photoluminescence and optically stimulated luminescence measurements of picosecond-excited SrS:Ce,Sm phosphor
Authors: Ravotti F. , Benoit D. , Lefebvre P. , Valvin P. , Vaillé J.-R. , Dusseau L. , Fesquet J. , Gasiot J.
Published: December 2007

Doubly activated alkaline-earth phosphors are known to present luminescent and charge-storage properties. In this work, we investigate the photoluminescence (PL) and the optically stimulated luminescence (OSL) of the SrS:Ce,Sm phosphor by means of time-resolved spectroscopy with excitation laser pulses of 2ps duration. By comparing the PL measurements obtained with direct UV excitation and the OSL experiments performed using infrared wavelength, it was possible to measure a charge conversion lifetime of about 2.5±1ns. A luminescence lifetime of 36±1ns has also been found. These measurements are presented and discussed in connection with applications where the speed of the SrS:Ce,Sm luminescence is a crucial parameter.
Fast magnetosonic waves launched by transient, current sheet reconnection
Authors: Longcope D. W. , Priest E. R.
Published: December 2007

A model is investigated describing the resistive dissipation of a finite, two-dimensional current sheet subject to suddenly enhanced resistivity. The resistivity rapidly diffuses the current to a distance where it couples to fast magnetosonic modes. The current then propagates away as a sheath moving at the local Alfvén speed. A current density peak remains at the X-point producing a steady electric field independent of the resistivity. This transfers flux across the separatrix at a rate consistent with the external wave propagation. The majority of the magnetic energy stored by the initial current sheet is converted into kinetic energy, far from the reconnection site, during the fast mode propagation.
Influence of polymer dielectrics on C60-based field-effect transistors
Authors: Zhou Jianlin , Zhang Fujia , Lan Lifeng , Wen Shangsheng , Peng Junbiao
Published: December 2007

Fullerene C60 organic field-effect transistors (OFETs) have been fabricated based on two different polymer dielectric materials, poly(methylmethacrylate) (PMMA) and cross-linkable poly(4-vinylphenol). The large grain size of C60 film and small number of traps at the interface of PMMA∕C60 were obtained with high electron mobility of 0.66cm2∕Vs in the PMMA transistor. The result suggests that the C60 semiconductor cooperating with polymer dielectric is a promising application in the fabrication of n-type organic transistors because of low threshold voltage and high electron mobility.
Large nonlinear absorption and refraction coefficients of carbon nanotubes estimated from femtosecond z-scan measurements
Authors: Kamaraju N. , Kumar Sunil , Sood A. K. , Guha Shekhar , Krishnamurthy Srinivasan , Rao C. N. R.
Published: December 2007

Nonlinear transmission of 80 and 140fs pulsed light with 0.79μm wavelength through single walled carbon nanotubes suspended in water containing sodium dodecyl sulfate is studied. Pulse-width independent saturation absorption and negative cubic nonlinearity are observed, respectively, in open and closed aperture z-scan experiments. The theoretical expressions derived to analyze the z-dependent transmission in the saturable limit require two photon absorption coefficient β0∼1.4cm∕MW and a nonlinear index γ∼−5.5×10−11cm2∕W to fit the data.
Nanotwin formation in copper thin films by stress/strain relaxation in pulse electrodeposition
Authors: Xu Di , Kwan Wei Lek , Chen Kai , Zhang Xi , Ozoliņš Vidvuds , Tu K. N.
Published: December 2007

Nanotwinned copper has been shown to greatly improve the yield strength while maintaining good electrical conductivity. It has great potential to be incorporated in the very-large-scale integration of Cu interconnect technology. The influence of stress/strain on nanotwin formation is studied using first principles calculations of the total crystal binding energy. Under biaxial stress, the total energy of strained Cu can be larger than that of strain-relaxed periodic nanotwinned Cu. We propose that, during pulse electrodeposition of Cu films, highly strained Cu can undergo recrystallization and grain growth to relax stress and form strain-relaxed nanotwins.
Step formation, faceting, and bunching in atomically flat SrTiO3 (110) surfaces
Authors: Bachelet R. , Valle F. , Infante I. C. , Sánchez F. , Fontcuberta J.
Published: December 2007

We demonstrate that single-terminated atomically flat surfaces of polar SrTiO3 (110) can be obtained by annealing in air at temperatures above 1000°C. We show that a morphological transition occurs from disordered step edges to faceted step edges in the range of 1000–1100°C with appropriate annealing conditions. The influence of miscut angles (polar and azimuthal) on the surface nanostructure, i.e., step bunching and faceting of step edges, is described. We show how the azimuthal angle has a critical role for the step-edge faceting and the step-bunching formation.
Stripes within Words Affect Reading
Authors: Wilkins Arnold J , Smith Jennifer , Willison Clare K , Beare Tom , Boyd Alexandra , Hardy Gemma , Mell Louise , Peach Charlotte , Harper Samantha
Published: December 2007

In a series of eight studies it is shown that the first peak in the horizontal autocorrelation of the image of a word (which captures the similarity in shape between the neighbouring strokes of letters) determines (i) the appearance of the words as striped; (ii) the speed with which the words are read, both aloud and silently; and (iii) the speed with which a paragraph of text can be searched. By subtly distorting the horizontal dimension of text, and thereby reducing the first peak in the horizontal autocorrelation, it is shown that the speed of word recognition can be increased. The increase in speed is greater in poor readers.
Global topological dominance in the left hemisphere
Authors: Wang Bo , Zhou Tian Gang , Zhuo Yan , Chen Lin
Published: December 2007

A series of experiments with right-handers demonstrated that the left hemisphere (LH) is reliably and consistently superior to the right hemisphere (RH) for global topological perception. These experiments generalized the topological account of lateralization to different kinds of topological properties (including holes, inside/outside relation, and “presence vs. absence”) in comparison with a broad spectrum of geometric properties, including orientation, distance, size, mirror-symmetry, parallelism, collinearity, etc. The stimuli and paradigms used were also designed to prevent subjects from using various nontopological properties in performing the tasks of topological discrimination. Furthermore, task factors commonly considered in the study of hemispheric asymmetry, such as response latency vs. accuracy, vertical vs. horizontal presentation, detection vs. recognition, and simultaneous vs. sequential judgment, were manipulated to not be confounding factors. Moreover, left-handed subjects were tested and showed the right lateralization of topological perception, in the opposite direction of lateralization compared with right-handers. In addition, the functional magnetic resonance imaging measure revealed that only a region in the left temporal gyrus was consistently more activated across subjects in the task of topological discrimination, consistent with the behavioral results. In summary, the global topological dominance in the LH is well supported by the converging evidence from the variety of paradigms and techniques, and it suggests a unified solution to the current major controversies on visual lateralization.
Nck adaptor proteins control the organization of neuronal circuits important for walking
Authors: Fawcett James P. , Georgiou John , Ruston Julie , Bladt Friedhelm , Sherman Andrew , Warner Neil , Saab Bechara J. , Scott Rizaldy , Roder John C. , Pawson Tony
Published: December 2007

The intracellular signaling targets used by mammalian axon guidance receptors to organize the nervous system
in vivo
are unclear. The Nck1 and Nck2 SH2/SH3 adaptors (collectively Nck) can couple phosphotyrosine (pTyr) signals to reorganization of the actin cytoskeleton and are therefore candidates for linking guidance cues to the regulatory machinery of the cytoskeleton. We find that selective inactivation of Nck in the murine nervous system causes a hopping gait and a defect in the spinal central pattern generator, which is characterized by synchronous firing of bilateral ventral motor neurons. Nck-deficient mice also show abnormal projections of corticospinal tract axons and defective development of the posterior tract of the anterior commissure. These phenotypes are consistent with a role for Nck in signaling initiated by different classes of guidance receptors, including the EphA4 receptor tyrosine kinase. Our data indicate that Nck adaptors couple pTyr guidance signals to cytoskeletal events required for the ipsilateral projections of spinal cord neurons and thus for normal limb movement.
Dysferlin Domain-containing Proteins, Pex30p and Pex31p, Localized to Two Compartments, Control the Number and Size of Oleate-induced Peroxisomes in Pichia pastoris
Authors: Yan Mingda , Rachubinski Dorian A. , Joshi Saurabh , Rachubinski Richard A. , Subramani Suresh
Published: December 2007

Yarrowia lipolytica Pex23p and Saccharomyces cerevisiae Pex30p, Pex31p, and Pex32p comprise a family of dysferlin domain–containing peroxins. We show that the deletion of their Pichia pastoris homologues, PEX30 and PEX31, does not affect the function or division of methanol-induced peroxisomes but results in fewer and enlarged, functional, oleate-induced peroxisomes. Synthesis of Pex30p is constitutive, whereas that of Pex31p is oleate-induced but at a much lower level relative to Pex30p. Pex30p interacts with Pex31p and is required for its stability. At steady state, both Pex30p and Pex31p exhibit a dual localization to the endoplasmic reticulum (ER) and peroxisomes. However, Pex30p is localized mostly to the ER, whereas Pex31p is predominantly on peroxisomes. Consistent with ER-to-peroxisome trafficking of these proteins, Pex30p accumulates on peroxisomes upon overexpression of Pex31p. Additionally, Pex31p colocalizes with Pex30p at the ER in pex19Δ cells and can be chased from the ER to peroxisomes in a Pex19p-dependent manner. The dysferlin domains of Pex30p and Pex31p, which are dispensable for their interaction, stability, and subcellular localization, are essential for normal peroxisome number and size. The growth environment-specific role of these peroxins, their dual localization, and the function of their dysferlin domains provide novel insights into peroxisome morphogenesis.
A novel genome-scale repeat finder geared towards transposons
Authors: Li Xuehui , Kahveci Tamer , Settles A. Mark
Published: December 2007

Motivation: Repeats are ubiquitous in genomes and play important roles in evolution. Transposable elements are a common kind of repeat. Transposon insertions can be nested and make the task of identifying repeats difficult.

Results: We develop a novel iterative algorithm, called Greedier, to find repeats in a target genome given a repeat library. Greedier distinguishes itself from existing methods by taking into account the fragmentation of repeats. Each iteration consists of two passes. In the first pass, it identifies the local similarities between the repeat library and the target genome. Greedier then builds graphs from this comparison output. In each graph, a vertex denotes a similar subsequence pair. Edges denote pairs of subsequences that can be connected to form higher similarities. In the second pass, Greedier traverses these graphs greedily to find matches to individual repeat units in the repeat library. It computes a fitness value for each such match denoting the similarity of that match. Matches with fitness values greater than a cutoff are removed, and the rest of the genome is stitched together. The similarity cutoff is then gradually reduced, and the iteration is repeated until no hits are returned from the comparison. Our experiments on the Arabidopsis and rice genomes show that Greedier identifies approximately twice as many transposon bases as those found by cross_match and WindowMasker. Moreover, Greedier masks far fewer false positive bases than either cross_match or WindowMasker. In addition to masking repeats, Greedier also reports potential nested transposon structures.

Contact:  xli@cise.ufl.edu
Structural flexibility in proteins: impact of the crystal environment
Authors: Hinsen Konrad
Published: December 2007

Motivation: In the study of the structural flexibility of proteins, crystallographic Debye-Waller factors are the most important experimental information used in the calibration and validation of computational models, such as the very successful elastic network models (ENMs). However, these models are applied to single protein molecules, whereas the experiments are performed on crystals. Moreover, the energy scale in standard ENMs is undefined and must be obtained by fitting to the same data that the ENM is trying to predict, reducing the predictive power of the model.

Results: We develop an elastic network model for the whole protein crystal in order to study the influence of crystal packing and lattice vibrations on the thermal fluctuations of the atom positions. We use experimental values for the compressibility of the crystal to establish the energy scale of our model. We predict the elastic constants of the crystal and compare with experimental data. Our main findings are (1) crystal packing modifies the atomic fluctuations considerably and (2) thermal fluctuations are not the dominant contribution to crystallographic Debye-Waller factors.

Availability: The programs developed for this work are available as supplementary material at Bioinformatics Online.

Contact:  hinsen@cnrs-orleans.fr

Supplementary information: (1) A full derivation of the normal mode equations in a crystal and in a continuous medium. (2) A movie illustrating the lattice vibrations. Both supplements are available at Bioinformatics Online.
Power of monitoring surveys to detect abundance trends in depleted populations: the effects of density-dependent habitat use, patchiness, and climate change
Authors: Blanchard Julia L. , Maxwell David L. , Jennings Simon
Published: December 2007

Blanchard, J. L., Maxwell, D. L., and Jennings, S. 2008. Power of monitoring surveys to detect abundance trends in depleted fish populations: the effects of density-dependent habitat use, patchiness, and climate change. – ICES Journal of marine Science, 65: 111–120. Traditionally, trawl surveys were designed to collect fishery-independent data for assessing the population dynamics of commercially exploited species. However, trawl survey data are increasingly used to describe the abundance, distribution and ecology of a wide range of species in studies of climate change and fishing effects. These new uses of survey data suggest that improved understanding of the value and limitations of existing survey designs is required. We compared the power of different survey designs (where stations are fixed, fixed stratified, random, or random stratified) to detect known trends in the abundance of depleted populations. Modelled populations were characterized by different temperature preference, density-dependent habitat selection, and patterns of small-scale aggregation (patchiness). Temperature preferences and local patchiness had an influence on the power of different surveys to detect increases in abundance, and in some scenarios, survey-area indices would consistently underestimate or overestimate trends in overall abundance. As the distributions of many fish populations have shifted in response to climate change, exhibit distribution-abundance relationships, and have been depleted by fishing, we conclude that survey indices may provide partial or unreliable information on changes in the true abundance of the wider range of species now of interest. To disentangle the effects of fishing, climate, and biology on the abundance of fish populations, and to monitor the depletion and recovery of species threatened by fishing, there should be greater emphasis on coordinating the timing, areas of coverage, and methods of sampling of surveys of the Northeast Atlantic continental shelf.
Nurses' Knowledge of Heart Failure Self‐Management
Authors: Willette Elizabeth W. , Surrells Danielle , Davis Leslie L. , Bush Charles T.
Published: December 2007

Heart failure (HF) is increasing in prevalence. Patient education is essential and is included in both ambulatory and hospital performance measures used to ensure quality care. Nurses are often the primary providers of education to patients with HF. This study assessed nurses' knowledge of basic principles of HF self‐management. The study surveyed 49 nurses who regularly provided care to patients with HF at a hospital in the southeastern United States. A 20‐item, true/false survey was administered to participants. Mean HF self‐management knowledge score was 15.97 (79.85% correct). Consistent with previous studies, nurses scored lowest on knowledge related to transient dizziness (16.3% answered correctly), daily weight monitoring (36.2% answered correctly), and asymptomatic hypotension (58.3% answered correctly). Findings confirm previous work suggesting that nurses may not be adequately prepared to educate patients with HF about self‐management.
Readiness to Exercise: A Comparison of 3 Instruments and an Interview
Authors: Fish Anne F. , Frid David J. , Mitchell G. Lynn , Fish James L. , Christman Sharon K. , Astroth Kim S.
Published: December 2007

Exercise stage of change (ESOC), or readiness to exercise, has been measured using at least 13 instruments and 4 interviews, yet no comparison studies are available to determine optimal measures for use by health care providers. This pilot study compares ESOC classification between 3 instruments (scale‐ladder, scale‐true/false, and scale‐5 choice); explores the feasibility of using a face‐to‐face structured interview; compares classification between instruments and interview; and examines the influence of sex, age, and education level on stage classification. Thirty healthy adults completed ESOC instruments in random order and then the interview. Scale‐ladder and scale‐true/false instruments exhibited almost perfect agreement (weighted κ, 0.897). All instruments exhibited substantial agreement with interview (weighted κ, 0.620–0.790). Stage classification did not differ significantly by sex, age, or education level. The authors recommend word clarification revision of the scale‐5 choice instrument and further testing of the interview.
Echocardiographic Assessment of Aortic Stenosis in the Elderly
Authors: Mallavarapu Ravi K. , Mankad Sunil , Nanda Navin C.
Published: December 2007

Aortic stenosis is one of the most common valvular conditions affecting the elderly population. This article reviews the echocardiographic assessment of aortic stenosis in the elderly including the advantages and limitations of different modalities and the potential role of 3‐dimensional echocardiography in this special population.
Phylogeny of cytoplasmic incompatibility microorganisms in the parasitoid wasp genus Nasonia (Hymenoptera: Pteromalidae) based on 16S ribosomal DNA sequences
Authors: Breeuwer J. A. J. , Stouthamer R. , Barns S. M. , Pelletier D. A. , Weisburg W. G. , Werren J. H.
Published: December 2007

Cytoplasmic incompatibility results in embryo mortality in diploids, or all male offspring in haplodiploids, when individuals carrying different cytoplasmic factors are crossed. Cytoplasmic factors have been identified as intracellular micro‐organisms. Microbeinduced cytoplasmic incompatibility is found in many insect taxa and may play a role in reproductive isolation between populations. Such micro‐organisms cause bidirectional incompatibility between species of the parasitoid wasp genus Nasonia. The phylogenetic relationship of cytoplasmic incompatibility microorganisms (CIM) of different Nasonia species was analysed using their 16S ribosomal DNA (rDNA) sequence. Two 16S rDNA operons were detected in the CIM of each Nasonia species. Sequence analysis indicates that the Nasonia CIM are closely related and belong to the alpha group of the Proteobacteria.
Vitelline membrane biogenesis in Drosophila requires the activity of the α‐methyl dopa hypersensitive gene (1(2)amd) in both the germline and follicle cells
Authors: Konrad K. D. , Wang Degui , Marsh J. L.
Published: December 2007

The vitelline membrane of Drosophila eggs is composed of a family of proteins which are cross linked into an insoluble matrix with an overlying waxy layer that prevents desiccation. We present here three sets of experiments which show that integrity of the vitelline membrane requires the activity of the alpha methyl dopa hypersensitive (1(2)amdH or amd) gene in both egg chambers and follicle cells. We show that loss of amd activity either by dietary administration of inhibitors or in genetic mosaics of either the germ line or follicle cells leads to production of defective vitelline membranes and by in situ hybridization, that amd is expressed in both nurse cells and follicle cells. The amd gene product is the first non‐structural protein gene described whose activity is required for vitelline membrane biosynthesis. Given its unique role in insects and its demonstrated sensitivity to dietary inhibitors, the amd gene product poses an attractive target for insect control.
Codon preference of Aedes aegypti and Aedes albopictus
Authors: Argentine J. A. , James A. A.
Published: December 2007

The codon bias of two Aedes mosquito species was examined using a sign test. In general, there appeared to be some preference for C + G at the third base position, although this was not statistically significant. While amino acids such as phenylalanine and tyrosine clearly displayed biases, others such as valine and serine appeared to have little or no bias for any particular codon. Three homologous genes of Aedes aegypti and Drosophila melanogaster were compared using the chi‐square test and the codon bias of the two species compared. Drosophila melanogaster was found to have a much stronger bias for C + G at the third base position compared to Aedes. The implications and usefulness of the codon bias are discussed.
Random amplified polymorphic DNA (RAPD) markers readily distinguish cryptic mosquito species (Diptera: Culicidae: Anopheles)
Authors: Wilkerson R. C. , Parsons T. J. , Albright D. G. , Klein T. A. , Braun M. J.
Published: December 2007

The usefulness of random amplified polymorphic DNA (RAPD) was examined as a potential tool to differentiate cryptic mosquito species. It proved to be a quick, effective means of finding genetic markers to separate two laboratory populations of morphologically indistinguishable African malaria vectors, Anopheles gambiae and An. arabiensis. In an initial screening of fiftyseven RAPD primers, 377 bands were produced, 295 of which differed between the two species. Based on criteria of interpretability, simplicity and reproducibility, thirteen primers were chosen for further screening using DNA from thirty individuals of each species. Seven primers produced diagnostic bands, five of which are described here. Some problematic characteristics of RAPD banding patterns are discussed and approaches to overcome these are suggested.
Characterization of a cDNA clone encoding a glycine‐rich cuticular protein of Tenebrio molitor: developmental expression and effect of a juvenile hormone analogue
Authors: Bouhin H. , Charles J.‐P. , Quennedey B. , Courrent A. , Delachambre J.
Published: December 2007

The complete sequence of a cDNA clone, isolated from epidermal mRNA of Tenebrio molitor using a monoclonal antibody raised against an adult‐specific cuticular antigen only present in the hard cuticle, was obtained after primer extension at the 5′ end. From this cDNA sequence, the deduced protein encompasses 199 amino acids (including a signal peptide) with a total molecular weight of 20.7 kDa. The protein exhibits a bipartite structure: glycine‐rich region located in its NH2‐terminal part and a carboxy‐terminal domain sharing homologies with other cuticular proteins of Orthoptera, Diptera and Lepidoptera. In‐situ hybridization analysis shows that the corresponding mRNA is present only in epidermal cells secreting the adult fibrous cuticle destined to become heavily sclerotized. In supernumerary pupae obtained after the application of the juvenile hormone analogue (JHA) to newly ecdysed pupae, the mRNA was undetectable, indicating that JHA can prevent the switch to the adult programme. However, in pupal‐adult intermediates, obtained when JHA is applied later, the mRNA is detected.
Genetic variability in the social bee Lasioglossum marginatum and a cryptic undescribed sibling species, as detected by DNA fingerprinting and allozyme electrophoresis
Authors: Blanchetot A. , Packer L.
Published: December 2007

DNA fingerprints (DNAfp) were obtained for three widely separated samples of bee related to Lasioglossum marginatum using the M13 sequence as a probe. Bee samples were obtained from France (three localities separated by at most 20 km), Greece and India. All European populations exhibited almost identical profiles with similarity indices (S) of over 98% within a French sample, 94% among Greek bees and 90% between Greek and French bees. The DNAfp profiles of Indian bees showed more polymorphism (intrapopulation S= 77%) and were quite dissimilar to the European samples (S= 55% and 56% to French and Greek samples, respectively). The similarity between populations separated by over 2000 km is higher than among unrelated individuals within a population in two other bee species and the tsetse fly. Data from allozyme electrophoresis shows parallel variation to that obtained with DNAfp and the genetic differences between Indian and European samples are strikingly large (Indian and European populations shared no alleles at 14 out of 47 loci surveyed) such that no more than one species must be involved. Nonetheless, the samples are indistinguishable morphologically. We argue that chronically low effective population size in these species results in low levels of genetic variability and that this, combined with a genetic bottleneck during the speciation event and colonization of Europe, may have resulted in both the extremely low levels of DNAfp variation in European bees and the large number of fixed allelic differences between European and Indian samples. We conclude that DNAfp may be particularly useful as a tool to study population level phenomena in organisms with only moderate levels of DNAfp variability and that the Hymenoptera may be particularly appropriate model systems for such research.
Native and baculovirus‐expressed forms of the immunoprotective protein BM86 from Boophilus microplus are anchored to the cell membrane by a glycosylphosphatidyl inositol linkage
Authors: Richardson M. A. , Smith D. R. J. , Kemp D. H. , Tellam R. L.
Published: December 2007

A glycoprotein (BM86) from the gut cells of the cattle tick Boophilus microplus, when used to vaccinate cattle, has been shown to protect cattle from tick infestation. A recombinant BM86 protein is the principal component of a novel tick vaccine currently under development. The nature of the anchorage of BM86 to tick gut epithelial cells has been investigated using BM86 from B. microplus and recombinant BM86 proteins expressed in insect cells using the baculovirus expression system. BM86 from B. microplus and a full length recombinant BM86 are shown to be anchored to the extracellular surface of tick gut epithelial cells and baculovirus‐infected insect cells, respectively by a glycosyl‐phosphatidyl inositol membrane anchor. A recombinant BM86 truncated by the removal of a hydrophobic region coding for thirty amino acids at the carboxy‐terminal end was secreted from baculovirus‐infected Sf9 cells. This secreted form of recombinant BM86 showed strong protective activity against ticks in cattle vaccinated with this protein.
Mediterranean fruit fly, Ceratitis capitata (Wiedemann), mitochondrial DNA: genes and secondary structures for six t‐RNAs
Authors: Frohlich D. R. , Robinson A. S. , Wells M. A.
Published: December 2007

The polymerase chain reaction was used to amplify six mitochondrial t‐RNAs for Ala, Arg, Asn, Ser, Glu and Phe between genes for mitochondrial NADH dehydrogenases 3 and 5. With respect to Drosophila yakuba the gene order and direction of transcription is completely conserved. Analysis of secondary structure shows complete conservation of the anticodon loops but a number of differences in the dihydrouridine and TψC loops with respect to Drosophila. However, differences are such that tertiary interactions that stabilize stacking are preserved. The use of the reported sequence in combination with PCR to explore population variability is discussed.
A glutathione S‐transferase gene of the vector mosquito, Anopheles gambiae
Authors: Reiss R. A. , James A. A.
Published: December 2007

A cDNA (D7‐8B) 1456 nucleotides in length was isolated from an adult, female‐specific Anopheles gambiae library and identified as a member of the glutathione S‐transferase (GST) gene family by virtue of the inferred amino acid sequence. The gene, AgGST2‐1, specifies a protein that is 57% identical to the Drosophila melanogaster gene, DmGST‐2. The conceptual translation product also shows similarity to the jt family of vertebrate GSTs. Northern analysis reveals multiple and abundant transcription products in larval, pupal and adult RNA preparations. Southern analyses of genomic DNA and hybridizations in situ to polytene chromosomes both suggest that there are multiple members of the GST gene family in Anopheles gambiae.
Characterization of differences between whiteflies using RAPD‐PCR
Authors: Gawel N. J. , Bartlett A. C.
Published: December 2007

The B biotype of the sweetpotato whitefly, Bemisia tabaci (Gennadius) has caused over $200 million in crop damage in the US during 1992. The taxonomic classification of the A and B biotypes of B. tabaci is unclear. We used RAPD‐PCR to demonstrate DNA differences between the A and B biotypes of this insect. Ail twenty of the RAPD primers tested distinguished readily between the biotypes. DNA extracted from individual eggs and nymphs showed identical differences. RAPD‐based genetic similarity statistics indicate that these two biotypes of B. tabaci were no more similar to each other than to two other whitefly species: bayberry whitefly (Parabemisia myri‐cae) or banded winged whitefly (Trialeurodes abutilo‐nea). These results indicate that RAPD‐PCR may be useful in distinguishing closely related organisms, but may not be useful in determining higher classification of insects. Before the taxonomic status of B. tabaci biotypes A and B can be determined, results from other genetic, morphological and physiological examinations will have to be compared.
In Drosophila Kc cells 20‐OHE induction of the 60C β3 tubulin gene expression is a primary transcriptional event
Authors: Chapel S. , Sobrier M. L. , Montpied P. , Micard D. , Bruhat A. , Couderc J. L. , Dastugue B.
Published: December 2007

In Drosophila Kc cells, the 60C 03 tubulin transcription unit, whose expression is induced by 20‐hydroxy‐ecdysone (20‐OHE), has the same structure as in Drosophila. This gene is characterized by an unusual 5 intron of regulating importance, by an alternatively spliced second intron and by a long 3 transcribed but untranslated region. This gene codes for two β3 tubulin isoforms with one amino acid difference. We have established that β3 tubulin gene expression is transcriptionally regulated by the steroid hormone in a time and hormonal concentration‐dependent fashion, without requirement of protein synthesis. This implies that this transcriptional induction is a primary event and that this gene is probably a direct target for the 20‐OHE receptor.
Variation in the ribosomal RNA cistron among host‐adapted races of an aphid (Schizaphis graminum)
Authors: Black W. C.
Published: December 2007

The greenbug, Schizaphis graminum, is an aphid species that consists of races that can be separated based on morphology, life histories, cytogenetics, mitochondrial DNA RFLPs and virulence to plant culti‐vars. Variation in the greenbug rDNA multigene family was studied to determine the extent to which rDNA cistrons have diverged among and within races. A restriction map of the rDNA cistron was constructed. Probing DNA from different races with subclones from rDNA coding regions and internal spacers identified little variation. However, probing with subclones of the intergenic spacer (IGS) identified continuous length variation within and among races. Race specific patterns were identified. Within a race, almost continuous variation in total IGS length was detected and asexual lineages possessed distinct patterns useful in genetic fingerprinting studies.
The Hsp70 heat‐shock gene family of the mosquito Anopheles albimanus
Authors: Benedict M. Q. , Cockburn A. F. , Seawright J. A.
Published: December 2007

Four Hsp70 genes of the malaria vector Anopheles albimanus were isolated from a genomic DNA library as two non‐overlapping clones each containing a pair of divergently transcribed genes having 75% DNA sequence similarity to the protein‐coding regions of the Drosophila metanogaster Hsp70genes. The clones were assigned to two loci on chromosome 2R by in situ hybridization. These clones hybridize strongly to heat‐shock but only weakly to non‐shocked mosquito RNA. The Hsp70 gene family of A. albimanus is undergoing concerted evolution probably by gene conversion. The general arrangement of the genes suggests that divergently transcribed pairs of genes at two loci is an ancient Dipteran arrangement predating the Nematocera/Cyclorrapha divergence.
The mitochondrial genome of the mosquito Anopheles gambiae: DNA sequence, genome organization, and comparisons with mitochondrial sequences of other insects
Authors: Beard C. B. , Hamm D. Mills , Collins F. H.
Published: December 2007

The entire 15,363 bp mitochondrial genome was cloned and sequenced from the mosquito Anopheles gambiae. With respect to the protein‐coding genes, rRN A genes and the control region, the gene order was identical to that reported for other insects. There were significant differences, however, in the position and orientation of specific tRNA loci. The overall nucleotide composition was heavily biased towards adenine and thymine, which accounted for 77.6% of all nucleotides. Comparisons were made with the mitochondrial genomes of other insects on the basis genome size and organization, DNA and putative amino acid sequence data, nucleotide substitutions, codon usage and bias, and patterns of AT enrichment.
Five major subfamilies of mariner transposable elements in insects, including the Mediterranean fruit fly, and related arthropods
Authors: Robertson H. M. , MacLeod E. G.
Published: December 2007

We have used a PCR assay to screen 404 insects and related arthropods for mariner elements using primers corresponding to amino acids conserved between the mariner elements of Drosophila mauritiana and a moth, Hyalophora cecropia. Potential mariner elements were detected in sixty‐three species, representing ten insect orders as well as a centipede and a mite. Phylogenetic analysis of the PCR fragment sequences from thirty species identifies five major subfamilies of mariners. Many species have representatives of multiple subfamilies in their genomes, and the Medfly is an extreme example with representatives of four subfamilies. Two instances of recent horizontal transfer of mariner elements include at least three species each. The widespread but sporadic distribution of mariner elements suggests they are excellent candidates for development as transformation vectors for non‐drosophilids.
Nuclear DNA sequence divergence between parapatric subspecies of the grasshopper Chorthippus parallelus
Authors: Cooper S. J. B. , Hewitt G. M.
Published: December 2007

Sequence data from a non‐coding nuclear DNA segment (CpnI‐1) was used to investigate the divergence between Spanish and French subspecies of the grasshopper Chorthippuspara/us which form a hybrid zone in the Pyrenees. The spatial distribution of eighteen Cpnl‐1 sequence haplotypes from eighteen French and fifteen Spanish populations and phylogenetic analyses using both distance and parsimony procedures provide strong evidence that the Py renean hybrid zone was formed by postglacial secondary contact and that the French subspecies arose by range expansion from a Balkan or Italian refugium. In addition, the data provide evidence for subdivision between grasshoppers from Northern Spain and those from Central and Pyrenean Spanish populations.
ALS and SAD‐like nicotinic acetylcholine receptor subunit genes are widely distributed in insects
Authors: Sgard F. , Obosi L A. , King L. A. , Windass J. D.
Published: December 2007

Segments of nicotinic acetylcholine receptor α sub‐unit genes have been isolated from a panel of insect species by polymerase chain reaction, using degenerate oligonucleotide primers designed to recognize conserved regions of the Drosophila melanogaster ALS and SAO genes. The amplified segments encode elements of typical a‐subunits anticipated to play roles in ligand binding and ion channel formation. Each is also clearly either ALS or SAD‐like. The predicted protein sequences display extremely high levels of conservation (over 85% for each subtype) even though derived from very distantly related insect species.
Genes expressed during the differentiation of the pupal wings are also transiently expressed during the larval moult in Bombyx mori
Authors: Chareyre P. , Guillet C. , Besson M. T. , Fourche J. , Bosquet G.
Published: December 2007

By a differential screening of cDNA libraries made with RNAs present in differentiating imaginal wing discs of Bombyx mori, we have isolated clones whose expression is dramatically modified during the formation of the pupal wings. The RNAs corresponding to all but one of these clones are also transiently accumulated in the wing primordia during the last larvo‐larval moult and in response to 20‐hydroxyecdysone injections. If the injections are made to juvenilized larvae the expression of the same genes is stimulated but the range of the stimulation is reduced. It is suggested that in Bombyx, cells of the wings reach the pupal stage of differentiation by steps corresponding to the phases during which high levels of ecdysteroids are present.
A family of U1 pseudogenes in Bombyx mori may be derived from an ancestral pseudogene
Authors: Vega L. R. , Amengual J. , Herrera R. J.
Published: December 2007

Seven EMBL‐4 lambda clones containing U1 small nuclear RNA sequences were isolated from a Bombyx mori genomic library. Six of the seven represent unique sequences. The six unique U1 sequences exhibit fixed point 3‐end truncation. Five out of the six clones share immediate 3‐end flanking sequences while two share 5‐end flanking sequences. Fixed point 3‐end truncation and a hierarchy of shared to unique diagnostic mutations may suggest a family of U1 pseudogenes generated from a reverse‐transcribed class II pseudogene in B. mori. An ancestral ‘master’ U1 pseudogene capable of RNA‐ and/or DNA‐mediated transposition may give rise to generations of U1 pseudogenes that include the original pseudogene's flanking sequences. Identical 3‐end truncation in some of these U1 sequences can be explained by RNA self‐priming due to intra‐strand binding prior to reverse transcription.