bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural evidence of secondary phase segregation from the Raman vibrational modes in Zn1−xCoxO (<x<0.6)
Authors: Wang Xuefeng , Xu Jianbin , Yu Xiaojiang , Xue Kun , Yu Jiaguo , Zhao Xiujian
Published: July 2007

Micro-Raman measurements were performed to study the influence of Co doping on the lattice dynamic properties of the host ZnO. The structural evidence of secondary phase segregation was detected from two distinct phonon vibrational modes at around 472 and 678cm−1 in Zn1−xCoxO (0<x<0.6) ternary alloys with x above 0.098. In addition, an intense, broad, and symmetric phonon vibration was apparent at about 530cm−1 for alloys with x not more than 0.155. The authors suggest the shallow donor defects bound on the Co sites rather than the local vibrational mode involving Co motion as the origin.
Characterization of protein-folding pathways by reduced-space modeling
Authors: Kmiecik Sebastian , Kolinski Andrzej
Published: July 2007

Ab initio
simulations of the folding pathways are currently limited to very small proteins. For larger proteins, some approximations or simplifications in protein models need to be introduced. Protein folding and unfolding are among the basic processes in the cell and are very difficult to characterize in detail by experiment or simulation. Chymotrypsin inhibitor 2 (CI2) and barnase are probably the best characterized experimentally in this respect. For these model systems, initial folding stages were simulated by using CA–CB–side chain (CABS), a reduced-space protein-modeling tool. CABS employs knowledge-based potentials that proved to be very successful in protein structure prediction. With the use of isothermal Monte Carlo (MC) dynamics, initiation sites with a residual structure and weak tertiary interactions were identified. Such structures are essential for the initiation of the folding process through a sequential reduction of the protein conformational space, overcoming the Levinthal paradox in this manner. Furthermore, nucleation sites that initiate a tertiary interactions network were located. The MC simulations correspond perfectly to the results of experimental and theoretical research and bring insights into CI2 folding mechanism: unambiguous sequence of folding events was reported as well as cooperative substructures compatible with those obtained in recent molecular dynamics unfolding studies. The correspondence between the simulation and experiment shows that knowledge-based potentials are not only useful in protein structure predictions but are also capable of reproducing the folding pathways. Thus, the results of this work significantly extend the applicability range of reduced models in the theoretical study of proteins.
Combinatorial protein therapy of angiogenic and arteriogenic factors remarkably improves collaterogenesis and cardiac function in pigs
Authors: Lu Huixia , Xu Xinsheng , Zhang Mei , Cao Renhai , Bråkenhielm Ebba , Li Changjiang , Lin Huili , Yao Guihua , Sun Huiwen , Qi Lihang , Tang Mengxiong , Dai Hongyan , Zhang Yanen , Su Runyi , Bi Yanwen , Zhang Yun , Cao Yihai
Published: July 2007

Establishment of functional and stable collaterals in the ischemic myocardium is crucial to restoring cardiac function after myocardial infarction. Here, we show that only dual delivery of a combination of angiogenic and arteriogenic factors to the ischemic myocardium could significantly reestablish stable collateral networks and improve myocardial perfusion and function. A combination of FGF-2 with PDGF-BB, two factors primarily targeting endothelial cells and vascular smooth muscle cells, remarkably promotes myocardial collateral growth and stabilizes the newly formed collateral networks, which significantly restore myocardial perfusion and function. Using various members of the PDGF family together with FGF-2 in an angiogenesis assay, we demonstrate that PDGFR-α is mainly involved in angiogenic synergism, whereas PDGFR-β mediates vessel stability signals. Our findings provide conceptual guidelines for the clinical development of proangiogenic/arteriogenic factors for the treatment of ischemic heart disease.
TLR9 agonist acts by different mechanisms synergizing with bevacizumab in sensitive and cetuximab-resistant colon cancer xenografts
Authors: Damiano Vincenzo , Caputo Rosa , Garofalo Sonia , Bianco Roberto , Rosa Roberta , Merola Gerardina , Gelardi Teresa , Racioppi Luigi , Fontanini Gabriella , De Placido Sabino , Kandimalla Ekambar R. , Agrawal Sudhir , Ciardiello Fortunato , Tortora Giampaolo
Published: July 2007

Synthetic agonists of Toll-like receptor 9 (TLR9), a class of agents that induce specific immune response, exhibit antitumor activity and are currently being investigated in cancer patients. Intriguingly, their mechanisms of action on tumor growth and angiogenesis are still incompletely understood. We recently discovered that a synthetic agonist of TLR9, immune modulatory oligonucleotide (IMO), acts by impairing epidermal growth factor receptor (EGFR) signaling and potently synergizes with anti-EGFR antibody cetuximab in GEO human colon cancer xenografts, whereas it is ineffective in VEGF-overexpressing cetuximab-resistant GEO cetuximab-resistant (GEO-CR) tumors. VEGF is activated by EGFR, and its overexpression causes resistance to EGFR inhibitors. Therefore, we used IMO and the anti-VEGF antibody bevacizumab as tools to study IMO's role on EGFR and angiogenesis and to explore its therapeutic potential in GEO, LS174T, and GEO-CR cancer xenografts. We found that IMO enhances the antibody-dependent cell-mediated cytotoxicity (ADCC) activity of cetuximab, that bevacizumab has no ADCC, and IMO is unable to enhance it. Nevertheless, the IMO-plus-bevacizumab combination synergistically inhibits the growth of GEO and LS174T as well as of GEO-CR tumors, preceded by inhibition of signaling protein expression, microvessel formation, and human, but not murine, VEGF secretion. Moreover, IMO inhibited the growth, adhesion, migration, and capillary formation of VEGF-stimulated endothelial cells. The antitumor activity was irrespective of the TLR9 expression on tumor cells. These studies demonstrate that synthetic agonists of TLR9 interfere with growth and angiogenesis also by EGFR- and ADCC-independent mechanisms affecting endothelial cell functions and provide a strong rationale to combine IMO with bevacizumab and EGFR inhibitory drugs in colon cancer patients.
Phenotypic and functional features of human Th17 cells
Authors: Annunziato Francesco , Cosmi Lorenzo , Santarlasci Veronica , Maggi Laura , Liotta Francesco , Mazzinghi Benedetta , Parente Eliana , Filì Lucia , Ferri Simona , Frosali Francesca , Giudici Francesco , Romagnani Paola , Parronchi Paola , Tonelli Francesco , Maggi Enrico , Romagnani Sergio
Published: July 2007

T helper (Th) 17 cells represent a novel subset of CD4+ T cells that are protective against extracellular microbes, but are responsible for autoimmune disorders in mice. However, their properties in humans are only partially known. We demonstrate the presence of Th17 cells, some of which produce both interleukin (IL)-17 and interferon (IFN)-γ (Th17/Th1), in the gut of patients with Crohn's disease. Both Th17 and Th17/Th1 clones showed selective expression of IL-23R, CCR6, and the transcription factor RORγt, and they exhibited similar functional features, such as the ability to help B cells, low cytotoxicity, and poor susceptibility to regulation by autologous regulatory T cells. Interestingly, these subsets also expressed the Th1-transcription factor T-bet, and stimulation of these cells in the presence of IL-12 down-regulated the expression of RORγt and the production of IL-17, but induced IFN-γ. These effects were partially inhibited in presence of IL-23. Similar receptor expression and functional capabilities were observed in freshly derived IL-17–producing peripheral blood and tonsillar CD4+ T cells. The demonstration of selective markers for human Th17 cells may help us to understand their pathogenic role. Moreover, the identification of a subset of cells sharing features of both Th1 and Th17, which can arise from the modulation of Th17 cells by IL-12, may raise new issues concerning developmental and/or functional relationships between Th17 and Th1.
The Role of the Cytoplasmic Pore in Inward Rectification of Kir2.1 Channels
Authors: Kurata Harley T. , Cheng Wayland W. , Arrabit Christine , Slesinger Paul A. , Nichols Colin G.
Published: July 2007

Steeply voltage-dependent block by intracellular polyamines underlies the strong inward rectification properties of Kir2.1 and other Kir channels. Mutagenesis studies have identified several negatively charged pore-lining residues (D172, E224, and E299, in Kir2.1) in the inner cavity and cytoplasmic domain as determinants of the properties of spermine block. Recent crystallographic determination of the structure of the cytoplasmic domains of Kir2.1 identified additional negatively charged residues (D255 and D259) that influence inward rectification. In this study, we have characterized the kinetic and steady-state properties of spermine block in WT Kir2.1 and in mutations of the D255 residue (D255E, A, K, R). Despite minimal effects on steady-state blockade by spermine, D255 mutations have profound effects on the blocking kinetics, with D255A marginally, and D255R dramatically, slowing the rate of block. In addition, these mutations result in the appearance of a sustained current (in the presence of spermine) at depolarized voltages. These features are reproduced with a kinetic model consisting of a single open state, two sequentially linked blocked states, and a slow spermine permeation step, with residue D255 influencing the spermine affinity and rate of entry into the shallow blocked state. The data highlight a “long-pore” effect in Kir channels, and emphasize the importance of considering blocker permeation when assessing the effects of mutations on apparent blocker affinity.
Unambiguous reconstruction of the complex amplitude reflection coefficient of a laterally homogeneous crystal using analyser-based phase-contrast imaging
Authors: Vine D. J. , Paganin D. M. , Pavlov K. M. , Podorov S. G.
Published: July 2007

A theoretical approach is developed to invert analytically a hard X-ray analyser-based phase-contrast image of a known weak object to recover the complex amplitude reflection coefficient (ARC) of a laterally homogeneous crystal. Numerical simulations test the method to recover the ARC from two systems of interest: a thick perfect crystal and a linearly strained thin film. For the latter model, a kinematical diffraction approximation was used to recover the one-dimensional deformation profile from the ARC.
PSAP: protein structure analysis package
Authors: Balamurugan B. , Roshan M. N. A. Md. , Shaahul Hameed B. , Sumathi K. , Senthilkumar R. , Udayakumar A. , Venkatesh Babu K. H. , Kalaivani M. , Sowmiya G. , Sivasankari P. , Saravanan S. , Vasuki Ranjani C. , Gopalakrishnan K. , Selvakumar K. N. , Jaikumar M. , Brindha T. , Michael Daliah , Sekar K.
Published: July 2007

A computing engine, theProtein Structure Analysis Package(PSAP), has been developed to calculate and display various hidden structural and functional features of three-dimensional protein structures. The proposed computing engine has several utilities to enable structural biologists to analyze three-dimensional protein molecules and provides an easy-to-use Web interface to compute and visualize the necessary features dynamically on the client machine. Users need to provide the Protein Data Bank (PDB) identification code or upload three-dimensional atomic coordinates from the client machine. For visualization, the free molecular graphics programsRasMolandJmolare deployed in the computing engine. Furthermore, the computing engine is interfaced with an up-to-date local copy of the PDB. The atomic coordinates are updated every week and hence users can access all the structures available in the PDB. The computing engine is free and is accessible online at http://iris.physics.iisc.ernet.in/psap/.
Calibration in a closed system: the case of X-ray diffraction analysis
Authors: Lwin Thaung
Published: July 2007

Knudsen [X-ray Spectrom.(1981),10, 54–561] proposed and demonstrated a least-squares approach to estimating the unknown parameters of a system of equations required for calibration in X-ray diffraction analysis. The approach is an ordinary least-squares approach which does not incorporate information on the errors of the measured intensities for a set of samples used as standards. The purpose of the present paper is to show that a functional relationship model can be applied to the problem to account for all the variation due to sampling and measurement error in the peak intensities. It is also shown that Knudsen's calibration estimator can be regarded as an approximation to a more general and potentially more efficient weighted least-squares estimator derived from the functional relationship model. The closeness of the approximation depends on the nature of the covariance structure of the intensity measurements.
A simple hermetic sample holder for X-ray diffraction analysis of uranium hydride
Authors: Ao Bingyun , Wang Xiaolin , Wei Yongjun , Zhang Yanzhi
Published: July 2007

In order to help resolve unknowns regarding aging effects of uranium during long-term storage of tritium, a number of experiments have been carried out by several researchers. However, almost no literature is available on the structural change of uranium tritide, mainly because its high toxicity and air-sensitivity render appropriate experiments very difficult. In this paper, a simple hermetic sample holder that fits the Philips X'Pert Pro X-ray diffractometer is described. It may be used to study the aging effects of uranium tritide during storage. The sample holder mainly consists of an aluminium container for sample storage and a Mylar window for X-ray measurements. This sample holder can also be used with other air-sensitive, radioactive and toxic materials. In this paper, the first results obtained from X-ray diffraction analysis of uranium hydride are presented.
On the numerical corrections of time-of-flight neutron powder diffraction data
Authors: Avdeev Maxim , Jorgensen James , Short Simine , Von Dreele Robert B.
Published: July 2007

Time-of-flight neutron powder diffraction data for NIST Standard Reference Materials have been used to study the adequacy of the peak profile model obtained from a convolution of back-to-back exponentials with a pseudo-Voigt function that is widely used in Rietveld refinement. It is shown that, while the empirical models ford-spacing (wavelength) dependence of Gaussian and Lorentzian components of the pseudo-Voigt function and rise exponent are satisfactory, the behavior of the decay exponent and peak positions demonstrate significant deviations, which can be corrected by numerical methods. The practical side of this process as implemented inGSASandFULLPROFand the effect of the corrections on the Rietveld analysis results are discussed.
Synthesis, structure, and stability of the high-temperature 6H-type perovskite phase Ba3BaSb2O9
Authors: Ling Chris D. , Avdeev Maxim , Aivazian Karina
Published: July 2007

The structure of Ba3BaSb2O9 is reported for the first time as a high-temperature phase with an ideal hexagonal BaTiO3-type structure (space group P63/mmc) and Rietveld-refined against high-temperature synchrotron X-ray powder diffraction data. The structure is remarkable for the extreme size difference between the pairs of face-sharing Sb5+O6 octahedra (with mean Sb—O bonds of 1.99 Å) and the single corner-sharing Ba2+O6 octahedra (with mean Ba—O bonds of 2.46 Å), which is greater than for any other reported 6H perovskite. This is consistent with the very different ionic radii of Sb5+ (0.60 Å) and Ba2+ (1.35 Å), and accounts for the instability of this phase at room temperature. The known symmetry-lowering modes of closely related 6H perovskites such as Ba3SrNb2O9 and Ba3SrTa2O9 are considered, but found not to account for the behaviour of Ba3BaSb2O9 on cooling from high temperatures.
A structural phase transition in NaTaOGeO4 and its relation to phase transitions in titanite
Authors: Malcherek Thomas
Published: July 2007

A structural phase transition from space-group symmetry P21/c to C2/c is reported for NaTaOGeO4 (NTGO). The critical temperature has been located at T
c = 116 K, based on the appearance of sharp diffraction maxima at positions h + k = 2n + 1 of reciprocal space on cooling below this temperature. Strongly anisotropic diffuse scattering in sheets normal to [001] is observable for T > T
c and persists up to ambient temperature. Similarities to phase transitions observed in other compounds of the titanite structure type are discussed. The symmetry properties of these phase transitions are reassessed on the basis of the structural data available. The primary order parameter is identified with the displacement of the transition metal cation M (M = Ta in NTGO) away from the centre of symmetry that it nominally occupies in the paraphase. The order parameter transforms as the Y_{2}^{-} representation. The anisotropic diffuse scattering is attributed to the one-dimensional correlation of local M displacements parallel to the direction of chains of trans-corner-sharing MO6 octahedra. The critical temperatures of the isomorphous phase transitions in various titanite-type compounds depend linearly on the squared transition-metal displacement measured in the ordered P21/c phase.
The impact of global warming and land‐use change on the pest status of rice and fruit bugs (Heteroptera) in Japan
Authors: KIRITANI K.
Published: July 2007

Infestation by rice and fruit bugs (Heteroptera) became a nationwide problem in Japan in the early 1970s. Nine rice bug species and three fruit bug species have been designated as economically important. Cropping restrictions for rice produced fallow paddy fields where various rice bugs reproduced and became abundant. Plautia crossota stali, Halyomorpha halys and Glaucias subpunctatus are dominant species of fruit bug that cause damage to a range of fruit crops. However, they require cones in order to complete their life cycle. Coniferous trees planted in the 1950s bore cones after 20 years. A dry and hot summer contributes to good masting the following year and good cone production, in turn, contributes to the abundance of fruit bugs in the third year. Thus, there is strong circumstantial evidence that land‐use changes were responsible for the abundance of both rice and fruit bugs during the last 30 years. Poleward range expansion was observed in Nezara viridula, Leptocorisa chinensis, G. subpunctatus and Paradasynus spinosus. A survey conducted to assess winter mortality revealed that every 1 °C rise in mean winter temperature resulted in a reduction of about 15% in winter mortality of N. viridula and H. halys in localities where the mean winter temperature ranges from 2 to 6 °C. In general, species with low developmental zero (T0) and small thermal constant (K) show the greatest increase in annual number of generations. Species with a high T0 for preoviposition period show the greatest increase in reproductive activity, while overwintering insects with a lower T0 tend to appear earlier in response to the elevation of temperature. Numbers of warnings issued by the prefectures on the occurrence of rice bugs and fruit bugs were correlated. Recent global warming operates in various ways, (e.g. by increasing annual number of generations, reproductive activity and food, to produce such correlation). There are no substantial bug problems in Korea where no significant land‐use changes have occurred. Rice bug outbreaks in Japan are predicted to become less frequent in the future, because there is no further scope for cropping restriction. Planting of coniferous trees has been continuously decreasing since 1970, but the area of coniferous forest is still almost the same. This suggests that the fruit bug problem will continue for the foreseeable future.
Linking climate change and species invasion: an illustration using insect herbivores
Authors: WARD NICOLA L. , MASTERS GREGORY J.
Published: July 2007

Climate change and invasive species are two of the most important ecological issues facing the world today. Yet, to date these two factors have largely been viewed independently. In order to prevent large‐scale economic and environmental damage and as a first step towards predicting and preventing invasions, it is important to understand the factors affecting invasions. Here, we focus on insect herbivores and link the climate change and invasive research fields. We illustrate using existing published research that life history traits can be useful indicators of future invasive potential. However, climate change will also affect propagule pressure and the communities into which invaders will arrive. With the aid of a meta‐analysis we show that climate‐induced community changes are likely to increase niche‐availability in the future, further exacerbating the problem of invasive species. It is timely and important that further research linking these two important ecological threats is undertaken.
Molecular characterization of the Aedes aegypti odorant receptor gene family
Authors: Bohbot J. , Pitts R. J. , Kwon H.‐W. , Rützler M. , Robertson H. M. , Zwiebel L. J.
Published: July 2007

The olfactory‐driven blood‐feeding behaviour of female Aedes aegypti mosquitoes is the primary transmission mechanism by which the arboviruses causing dengue and yellow fevers affect over 40 million individuals worldwide. Bioinformatics analysis has been used to identify 131 putative odourant receptors from the A. aegypti genome that are likely to function in chemosensory perception in this mosquito. Comparison with the Anopheles gambiae olfactory subgenome demonstrates significant divergence of the odourant receptors that reflects a high degree of evolutionary activity potentially resulting from their critical roles during the mosquito life cycle. Expression analyses in the larval and adult olfactory chemosensory organs reveal that the ratio of odourant receptors to antennal glomeruli is not necessarily one to one in mosquitoes.
The essence of nursing care: Polish nurses’ perspectives
Authors: Zarzycka Danuta , Ślusarska Barbara
Published: July 2007

Title.  The essence of nursing care: Polish nurses’ perspectives

Aim.  This paper is a report of a study to identify Polish nurses’ definition of the concept of nursing care.

Background.  Polish nursing currently is in a period of scientific research focusing on development of precise definitions of concepts. Definitions of nursing are influenced by culture, social expectations and healthcare systems. Accepted scientific definitions of concepts should be based on empirical verification that takes theoretical and practical perspectives into account.

Methods.  A survey questionnaire was constructed from analysis of a random sample of 27 essays about nursing care that had been completed by 300 Polish nurses. The survey questionnaire, which was designed to measure the essence of nursing care, was completed by 324 Polish nurses during 2004 and 2005.

Findings.  Analysis of survey questionnaire responses revealed that the essence of nursing care encompasses providing care, communicating, supporting, helping, assisting, accompanying and managing. Participants indicated that nursing care recipients include healthy persons, ill persons and persons at risk for disease.

Conclusion.  The concept of nursing care encompasses several traits or characteristics that can be applied to both well and ill people.
Understanding pre‐service teachers' computer attitudes: applying and extending the technology acceptance model
Authors: Teo T. , Lee C.B. , Chai C.S.
Published: July 2007

Abstract  Computers are increasingly widespread, influencing many aspects of our social and work lives, As we move into a technology‐based society, it is important that classroom experiences with computers are made available for all students. The purpose of this study is to examine pre‐service teachers' attitudes towards computers. This study extends the technology acceptance model (TAM) framework, with subjective norm and facilitating conditions acting as external variables. Results shows that perceived usefulness, perceived ease of use and subjective norm were significant determinants of pre‐service computer attitudes. Facilitating conditions did not influence computer attitude directly but through perceived ease of use. These findings demonstrate that social norm and facilitating conditions are potential variables that may be used to extend the TAM for research on computer attitudes.
Randomized comparison of a nutrient‐dense formula with an energy‐supplemented formula for infants with faltering growth
Authors: Clarke S. E. , Evans S. , MacDonald A. , Davies P. , Booth I. W.
Published: July 2007

Introduction  The practice of supplementing standard infant formula with energy for infants with faltering growth has been widespread. This increases energy density but disturbs the protein : energy ratio, and increases risks of microbial contamination and errors in feed preparation. This study aimed to compare the effectiveness of a nutrient‐dense formula (NDF) with an energy‐supplemented formula (ESF) in infants with faltering growth.

Methods  In an open, parallel, randomized study, 49 infants with faltering growth were randomized to receive a NDF (4.2 kJ mL−1) or an ESF (4.2 kJ mL−1), for 6 weeks. Anthropometry, biochemistry, feed intake, stool and vomit frequency were collected.

Results  No significant differences in tolerance, feed volumes or energy intakes were recorded but the NDF group received 42% more protein and 15–40% more vitamins and minerals. Blood urea concentration in the ESF group fell by 50% over the trial period, suggesting a suboptimal protein : energy ratio in the ESF feed. The NDF group retained a normal mean blood urea concentration, a higher urinary potassium concentration and did not have the significant fall in length z‐score seen in the ESF group.

Conclusion  Increasing the energy content of normal infant formula without also increasing protein and micronutrients should not be practiced in infants with faltering growth.
Learning disabilities within mental health services: are we adequately preparing nurses for the future?
Authors: CLARK L. L.
Published: July 2007

Current government policy dictates that where possible patients who have learning disabilities should be cared for within the framework of ordinary generic national health services, with specialist provision kept to a minimum. The mental health care of this client group may be problematic and diagnostic overshadowing can occur because of complex physical, emotional and behavioural issues. If the government agenda is to be followed, this will have an impact on both the pre‐ and post‐registration education of mental health nurses and therefore this must be addressed by the nursing regulatory bodies. There is also an argument for people who have a learning disability in addition to mental health problems to be considered a specialist group within generic mental health services as are other specific groups because of the complexity of their conditions.
Peer‐reviewed publication output of psychiatric nurses in the Republic of Ireland
Authors: HIGGINS A. , FARRELLY M.
Published: July 2007

Pre‐registration psychiatric nursing education, in the Republic of Ireland, has recently moved to a 4‐year degree programme, with the first cohort of psychiatric nursing graduants graduating in 2006. In addition, a number of other policy initiatives have taken place that will have a significant impact on psychiatric nursing practice, education and research activity. To provide a baseline for future benchmarking and evaluation, the year 2005 seemed an appropriate time to reflect on and record publications by psychiatric nurses in the Republic of Ireland. This article reports the findings of a study undertaken to identify psychiatric nursing publications in peer‐reviewed journals, with a view to establishing trends in publication, such as the type of publication, subject area and journal type. Emerging trends are identified and discussed in light of concurrent changes in psychiatric nursing and mental health care, and suggestions are made for future development of publication capacity.
The temporal development in a hybridizing population of wild and cultivated chicory (Cichorium intybusL.)
Authors: SØRENSEN B. S. , KIÆR L. P. , JØRGENSEN R. B. , HAUSER T. P.
Published: July 2007

Hybridization and its possible impacts is a subject of increased attention in connection with the risk of unintended gene flow from cultivated (including genetically modified) plants to wild relatives. Whether such gene flow by hybridization is likely to take place depends among other things on the persistence of the hybrids in a natural environment over time. To evaluate this, we studied an experimental hybridizing population of wild and cultivated chicories (Cichorium intybus) relative to a previous study on the same population 2 years earlier. We compared the genetic composition, morphology and fitness traits of plants from 2004 to the plants in the same plot in 2002. The majority of the plants in 2004 was more morphologically and genetically intermediate than in 2002. This indicates that no selection towards being wild‐like or cultivar‐like was present over the period of 2 years. Furthermore, no distinct fitness differences existed between the plants of 2004, probably due to most of the plants being intermediate. No hybridization barriers appeared to be present between wild and cultivated chicories beyond the F1generation, since F2hybrids and backcrosses were in abundance; in fact, hybrids of probably fourth or fifth generation were present. In conclusion, all results indicate that no barriers exist to the temporal persistence of chicory hybrids in a natural environment.
Population genetics of the wood‐decay fungus Phlebia centrifuga P. Karst. in fragmented and continuous habitats
Authors: FRANZÉN INA , VASAITIS RIMVYDAS , PENTTILÄ REIJO , STENLID JAN
Published: July 2007

The basidiomycete Phlebia centrifuga is a wood‐decay fungus characteristic for unmanaged old‐growth forests of spruce, a habitat that has become increasingly fragmented due to forest management. The aim of this study was to investigate the genetic population structures of P. centrifuga in both continuous and fragmented habitats, and estimate the potential impact of fragmentation on the genetic diversity of the fungus. Three hundred fifteen single spore isolates (representing 47 spore families and 33 single isolates) from eight populations across northern Europe (Russia, Finland, and Sweden) were screened with seven microsatellite markers and arbitrary primed polymerase chain reaction with the M13 minisatellite. The two molecular methods generally gave the same pattern for the genetic population structure. There were no significant differences between the observed and the expected heterozygosities, and the inbreeding coefficient (FIS) did not indicate any inbreeding. The fixation index (FST) revealed a general pattern with little to moderate genetic differentiation for the majority of populations, while the southernmost Swedish population Norra Kvill was the only one showing high differentiation from about half of the other populations. Swedish population Fiby with the shortest distance to the continuous habitat was moderately differentiated from most of the others and to the largest extent differed from geographically closest population of Norra Kvill. The results indicate that the fragmentation of old‐growth forest in Russia and Finland is more recent than the fragmentation in Sweden, and the genetic population structures of P. centrifuga in northern Europe might be related to differences in forest landscape dynamics between the two areas.
Population genetics of Plasmodium resistance genes in Anopheles gambiae: no evidence for strong selection
Authors: OBBARD D. J. , LINTON Y.‐M. , JIGGINS F. M. , YAN G. , LITTLE T. J.
Published: July 2007

Anopheles mosquitoes are the primary vectors for malaria in Africa, transmitting the disease to more than 100 million people annually. Recent functional studies have revealed mosquito genes that are crucial for Plasmodium development, but there is presently little understanding of which genes mediate vector competence in the wild, or evolve in response to parasite‐mediated selection. Here, we use population genetic approaches to study the strength and mode of natural selection on a suite of mosquito immune system genes, CTL4, CTLMA2, LRIM1, and APL2 (LRRD7), which have been shown to affect Plasmodium development in functional studies. We sampled these genes from two African populations of An. gambiae s.s., along with several closely related species, and conclude that there is no evidence for either strong directional or balancing selection on these genes. We highlight a number of challenges that need to be met in order to apply population genetic tests for selection in Anopheles mosquitoes; in particular the dearth of suitable outgroup species and the potential difficulties that arise when working within a closely‐related species complex.
Kin structure provides no explanation for intruders in social aphids
Authors: ABBOT PATRICK , CHHATRE VIKRAM
Published: July 2007

Nontraditional social organisms have received increasing attention in recent years, because they present opportunities to study the convergent properties of social evolution. Some aphid species are social, occurring in dense clones with specialized morphs that attack predators and parasites. Little is known about how social aphid colonies resolve conflicts of interest when clonal barriers break down.Pemphigus obesinymphaeis a North American gall‐forming social aphid that produces both nymphal defenders that protect natal clones, and specialized intruders that invade other nearby clones on their host plants. We tested the hypothesis that clones are arranged on their host plants in spatial clusters of related family groups, such that intruders would be biased towards movement within kin groups. Movement within and not between kin groups would then provide insight into the nature of conflict in this social aphid. We sampled eight sites in the eastern United States and in Arizona, and used eight microsatellite markers to estimate pairwise relatedness between spatial groups. We found little evidence of deviation from random distributions of genotypes on their host plants. Evidently,Pem. obesinymphaeintruders typically exploit unrelated clones, and spatial orientation provides no solution to the problem of ‘polyclonality’ in this species. We discuss implications of this result for our understanding of cooperation and conflict in social aphids.
Glacial refugia and recolonization pathways in the brown seaweed Fucus serratus
Authors: HOARAU G. , COYER J. A. , VELDSINK J. H. , STAM W. T. , OLSEN J. L.
Published: July 2007

The last glacial maximum (20 000–18 000 years ago) dramatically affected extant distributions of virtually all northern European biota. Locations of refugia and postglacial recolonization pathways were examined in Fucus serratus (Heterokontophyta; Fucaceae) using a highly variable intergenic spacer developed from the complete mitochondrial genome of Fucus vesiculosus. Over 1500 samples from the entire range of F. serratus were analysed using fluorescent single strand conformation polymorphism. A total of 28 mtDNA haplotypes was identified and sequenced. Three refugia were recognized based on high haplotype diversities and the presence of endemic haplotypes: southwest Ireland, the northern Brittany‐Hurd Deep area of the English Channel, and the northwest Iberian Peninsula. The Irish refugium was the source for a recolonization sweep involving a single haplotype via northern Scotland and throughout Scandinavia, whereas recolonization from the Brittany‐Hurd Deep refugium was more limited, probably because of unsuitable soft‐bottom habitat in the Bay of Biscay and along the Belgian and Dutch coasts. The Iberian populations reflect a remnant refugium at the present–day southern boundary of the species range. A generalized skyline plot suggested exponential population expansion beginning in the mid‐Pleistocene with maximal growth during the Eems interglacial 128 000–67 000 years ago, implying that the last glacial maximum mainly shaped population distributions rather than demography.
Genetic architecture in codling moth populations: comparison between microsatellite and insecticide resistance markers
Authors: FRANCK P. , REYES M. , OLIVARES J. , SAUPHANOR B.
Published: July 2007

The codling moth,Cydia pomonella, is renowned for developing resistance to insecticides and causing significant economic damage to pome fruits worldwide. In spite of its economic importance, little is known about the patterns of movement of this pest and the effects of insecticide treatment on the population genetic structure. Here, we investigated the genetic structure of the pest in 27 orchards from France, Italy, Armenia and Chile at seven microsatellite loci and two resistance markers [biochemical activity of cytochrome P450 oxidases and proportion of knockdown resistance(kdr) alleles in the sodium channel gene]. According to the microsatellite loci, we detected isolation by distance at the supranational scale but found no evidence of geographical structure among the 24 French orchards, which were mainly structured by the intensity of the insecticide treatments. Similarly, the highest levels of metabolic resistance associated with activity of the cytochrome P450 oxidases were detected in the most treated orchards. Thekdralleles were observed in southern France and Armenia where the pyrethroid insecticides were or have been intensively sprayed. The intensity of the insecticide treatments marginally affected the allelic richness in each orchard, but not the level of inbreeding. These results suggest important and high‐distance gene flow among the codling moth populations, which were mainly structured according to the history of insecticide applications. Differences in mutation‐migration‐drift equilibrium among treated and untreated orchards also suggest that insecticide applications are the main force regulating the local dynamics of codling moth populations.
Epidemiological and evolutionary consequences of targeted vaccination
Authors: WILLIAMS PAUL D. , DAY TROY
Published: July 2007

Recent theory has examined the way in which vaccination strategies are expected to influence the evolution of parasite virulence. Most of this work has assumed that vaccination is imposed on a homogeneous host population. However, host populations are typically composed of different types of individuals, with each type responding differently to infection. Moreover, actual interventions often focus treatment on those hosts that are likely to suffer the most ill effects of a particular disease. Here we consider the epidemiological and evolutionary consequences of interventions that focus vaccination on individuals expressing the greatest susceptibility to infection and/or the greatest vulnerability to mortality once infected. Our results indicate that predictions are very sensitive to the nature and degree of heterogeneity in susceptibility and vulnerability. They further suggest that accounting for realistic kinds of heterogeneity when contemplating targeted treatment plans and policies might provide a new tool in the design of more effective virulence management strategies.
Are clownfish groups composed of close relatives? An analysis of microsatellite DNA variation in Amphiprion percula
Authors: BUSTON PETER M. , BOGDANOWICZ STEVEN M. , WONG ALEX , HARRISON RICHARD G.
Published: July 2007

A central question of evolutionary ecology is: why do animals live in groups? Answering this question requires that the costs and benefits of group living are measured from the perspective of each individual in the group. This, in turn, requires that the group's genetic structure is elucidated, because genetic relatedness can modulate the individuals’ costs and benefits. The clown anemonefish, Amphiprion percula, lives in groups composed of a breeding pair and zero to four nonbreeders. Both breeders and nonbreeders stand to gain by associating with relatives: breeders might prefer to tolerate nonbreeders that are relatives because there is little chance that relatives will survive to breed elsewhere; nonbreeders might prefer to associate with breeders that are relatives because of the potential to accrue indirect genetic benefits by enhancing anemone and, consequently, breeder fitness. Given the potential benefits of associating with relatives, we use microsatellite loci to investigate whether or not individuals within groups of A. percula are related. We develop seven polymorphic microsatellite loci, with a number of alleles (range 2–24) and an observed level of heterozygosity (mean = 0.5936) sufficient to assess fine‐scale genetic structure. The mean coefficient of relatedness among group members is 0.00 ± 0.10 (n = 9 groups), and there are no surprising patterns in the distribution of pairwise relatedness. We conclude that A. percula live in groups of unrelated individuals. This study lays the foundation for further investigations of behavioural, population and community ecology of anemonefishes which are emerging as model systems for evolutionary ecology in the marine environment.
Cryptic differentiation in alpine‐endemic, high‐altitude butterflies reveals down‐slope glacial refugia
Authors: HAUBRICH KAROLA , SCHMITT THOMAS
Published: July 2007

The influence of cyclic climate fluctuations and their impact on high‐altitude species is still insufficiently understood. We therefore analysed in this study the genetic structure of cold‐adapted animals and their coherence with geographical distributions throughout the Late Quaternary. We analysed 588 individuals from 23 populations of the alpine‐endemic lesser mountain ringlet, Erebia melampus, by allozyme electrophoresis to detect its intraspecific differentiation. As an outgroup, we added one population of Erebia sudetica inalpina from Grindelwald (Swiss Alps). Seventeen of 18 loci were polymorphic. The mean FST over all samples was 37%. We detected strong differentiation into three lineages with the genetic distances between the two E. melampus groups being larger than between each of the two E. melampus groups and E. sudetica. The mean genetic distance among these three groups was 0.17. These results give evidence for the existence of a species complex within the E. melampus/sudetica group and indicate a discontinuous distribution within this group during at least the last ice age. One of them, E. sudetica inalpina, is found in the northern Alps and most probably had its Würm glacial refugium north of the glaciated Alps. The western E. melampus group might have had a refugium at the southwestern Alps margin, the eastern group in the lower altitudes of the southeastern and/or eastern Alps. In the latter, a further subdivision within this relict area is possible.
Changes in composition of cuticular biochemicals of the facultatively polygynous ant Petalomyrmex phylax during range expansion in Cameroon with respect to social, spatial and genetic variation
Authors: DALECKY AMBROISE , RENUCCI MARIELLE , TIRARD ALAIN , DEBOUT GABRIEL , ROUX MAURICE , KJELLBERG FINN , PROVOST ERICK
Published: July 2007

In social insects, biochemicals found at the surface of the cuticle are involved in the recognition process and in protection against desiccation and pathogens. However, the relative contribution of evolutionary forces in shaping diversity of these biochemicals remains largely unresolved in ants. We determined the composition of epicuticular biochemicals for workers sampled in 12 populations of the ant Petalomyrmex phylax from Cameroon. Genetic variation at 12 microsatellite markers was used to infer population history and to provide null expectations under the neutrality hypothesis. Genetic data suggest a recent southward range expansion of this ant species. Furthermore, there is a decline southward in the numbers of queens present in mature colonies. Here, we contrast the pattern of biochemical variation against genetic, social and spatial parameters. We thus provide the first estimates of the relative contribution of neutral and selective processes on variation of ant cuticular profile. Populations in migration–drift disequilibrium showed reduction of within‐population variation for genetic markers as well as for cuticular profiles. In these populations, the cuticular profile became biased towards a limited number of high molecular weight molecules. Within‐ and among‐population biochemical variation was explained by both genetic and social variation and by the spatial distribution of populations. We therefore propose that during range expansion of P. phylax, the composition of epicuticular compounds has been affected by a combination of neutral processes — genetic drift and spatially limited dispersal — and spatially varying selection, social organization and environmental effects.
Tenebrio beetle pupae show a conditioned behavioural response to pulse rotations of a geomagnetic field
Authors: VÁCHA MARTIN
Published: July 2007

Abstract Pupae of holometabolous insects are not motionless and insensitive developmental stages. Their behavioural display is restricted to rotations or contractions of the abdomen in a range of movements from the clearly visible to the microscopic of the order of tenths of microns. Pupae react spontaneously and surprisingly sensitively to mechanical, light or sound stimuli. In the present study, reactions of yellow mealworm beetle (Tenebrio molitor, L.) pupae to a geomagnetic field rotation are examined. By means of a micromechanical recording technique, peaks of abdominal contractions are monitored before and after magnetic treatment and show that spontaneous behavioural reaction to a magnetic pulse is insignificant. Nevertheless, using negative reinforcement training, a conditioned magneto‐sensitive reaction is elicited. These surprising sensory and behavioural capacities of an insect pupa are discussed.
The effect of selection for desiccation resistance on cold tolerance of Drosophila melanogaster
Authors: SINCLAIR BRENT J. , NELSON SEAN , NILSON THERESA L. , ROBERTS STEPHEN P. , GIBBS ALLEN G.
Published: July 2007

Abstract Low temperature and desiccation stress are thought to be mechanistically similar in insects, and several studies indicate that there is a degree of cross‐tolerance between them, such that increased cold tolerance results in greater desiccation tolerance and vice versa. This assertion is tested at an evolutionary scale by examining basal cold tolerance, rapid cold‐hardening (RCH) and chill coma recovery in replicate populations of Drosophila melanogaster selected for desiccation resistance (with controls for both selection and concomitant starvation) for over 50 generations. All of the populations display a RCH response, and there is no effect of selection regime on RCH or basal cold tolerance, although there are differences in basal cold tolerance between sampling dates, apparently related to inter‐individual variation in development time. Flies selected for desiccation tolerance recover from chill coma slightly, but significantly, faster than control and starvation‐control flies. These findings provide little support for cross‐tolerance between survival of near‐lethal cold and desiccation stress in D. melanogaster.