bluuebunny/crossref_metadata_2025 huggingface dataset:
Transition radiation energy loss in inductively coupled argon plasma
Authors: Ren Yuping , Long J. D. , Xu S.
Published: July 2007

This work studies the transition radiation energy loss in inductively coupled argon plasma. Energy loss channels due to ionization, momentum transfer, and radiation are investigated in argon plasma bounded by a cylindrical metal vessel. Radiation energy is calculated using the electron energy distribution function diagnosed by a Langmuir probe and the emission cross section. The measured electron energy is found to feature a Druyvesteyn-like distribution. Detailed emission lines and their relative intensity are investigated using high resolution optical emission spectroscopy. Radiation energy loss due to the blue lines (mainly 5p→4s transition) and red-IR lines (4p→4s transition) appears less prominent than that of the two ultraviolet emission lines originated from the transitions of the two lowest resonant levels to the ground state. Approximately 30% collisional energy loss is responsible for ionization, whereas only a few percent of the energy loss is attributed to elastic collision. Most energy loss is due to the transition radiation emission. These findings are remarkably important for controllable plasma aided materials processing.
Electromechanical detection in scanning probe microscopy: Tip models and materials contrast
Authors: Eliseev Eugene A. , Kalinin Sergei V. , Jesse Stephen , Bravina Svetlana L. , Morozovska Anna N.
Published: July 2007

The rapid development of nanoscience and nanotechnology in the last two decades was stimulated by the emergence of scanning probe microscopy techniques capable of accessing local material properties, including transport, mechanical, and electromechanical behaviors, on the nanoscale. Here, we analyze the general principles of electromechanical probing by piezoresponse force microscopy (PFM), a scanning probe technique applicable to a broad range of piezoelectric and ferroelectric materials. The relationship between vertical and lateral PFM signals and material properties is derived analytically for two cases: transversally isotropic piezoelectric materials in the limit of weak elastic anisotropy, and anisotropic piezoelectric materials in the limit of weak elastic and dielectric anisotropies. The integral representations for PFM response for fully anisotropic material are also obtained. The image formation mechanism for conventional (e.g., sphere and cone) and multipole tips corresponding to emerging shielded and strip-line-type probes is analyzed. Possible applications for orientation imaging on the nanoscale and molecular resolution imaging are discussed.
Study of self-assembly of symmetric coil-rod-coil ABA-type triblock copolymers by self-consistent field lattice method
Authors: Chen Ji-Zhong , Zhang Cheng-Xiang , Sun Zhao-Yan , An Li-Jia , Tong Zhen
Published: July 2007

The self-assembly of symmetric coil-rod-coil ABA-type triblock copolymer melts is studied by applying self-consistent field lattice techniques in a three-dimensional space. The self-assembled ordered structures differ significantly with the variation of the volume fraction of the rod component, which include lamellar, wave lamellar, gyroid, perforated lamellar, cylindrical, and spherical-like phases. To understand the physical essence of these phases and the regimes of occurrence, we construct the phase diagram, which matches qualitatively with the existing experimental results. Compared with the coil-rod AB diblock copolymer, our results revealed that the interfacial grafting density of the separating rod and coil segments shows important influence on the self-assembly behaviors of symmetric coil-rod-coil ABA triblock copolymer melts. We found that the order-disorder transition point changes from frod=0.5 for AB diblock copolymers to frod=0.6 for ABA triblock copolymers. Our results also show that the spherical-like and cylindrical phases occupy most of the region in the phase diagram, and the lamellar phase is found stable only at the high volume fraction of the rod.
Effect of ion-irradiation induced defects on the nanocluster Si∕Er3+ coupling in Er-doped silicon-rich silicon oxide
Authors: Seo Se-Young , Jeong Hoon , Shin Jung H. , Choi Han Woo , Woo Hyung Joo , Kim Joon Kon
Published: July 2007

The effect of ion-irradiation induced defects on the nanocluster Si∕Er3+ coupling in Er-doped silicon-rich silicon oxide (SRSO) thin film is investigated. Er-doped SRSO, which consists of silicon nanoclusters (nc-Si) in a SiO2 matrix, was fabricated using electron-cyclotron resonance plasma enhanced chemical vapor deposition using SiH4 and O2 with concurrent sputtering of Er followed by a high temperature annealing. Defects were introduced into the film via irradiation with 3MeV Si ions and subsequently removed by high temperature annealings. The authors find that ion irradiation reduces Er3+ luminescence from SRSO films, even when the excitation cross section and luminescence efficiency of Er3+ ions are completely restored. On the other hand, ion irradiation increases the intrinsic nc-Si luminescence and has little effect on the Er3+ luminescence from a similarly prepared, Er-doped SiO2 film, indicating that the presence of irradiation induced defects in the initial amorphous film can reduce the number of Er3+ ions available for nc-Si mediated luminescence by as much as a factor of 3.
Very large spontaneous electric polarization in BiFeO3 single crystals at room temperature and its evolution under cycling fields
Authors: Lebeugle D. , Colson D. , Forget A. , Viret M.
Published: July 2007

Electric polarization loops are measured at room temperature on highly pure BiFeO3 single crystals synthesized by a flux growth method. Because the crystals have a high electrical resistivity, the resulting low leakage currents allow the authors to measure a large spontaneous polarization in excess of 100μCcm−2, a value never reported in the bulk. During electric cycling, the slow degradation of the material leads to an evolution of the hysteresis curves eventually preventing full saturation of the crystals.
Rate constant for OH(Π2)+O(P3)→H(S2)+O2(Σg−3) reaction on an improved ab initio potential energy surface and implications for the interstellar oxygen problem
Authors: Xu Chuanxiu , Xie Daiqian , Honvault Pascal , Lin Shi Ying , Guo Hua
Published: July 2007

The authors report a global potential energy surface for the ground electronic state of HO2(X̃A″2), which improves upon the XXZLG potential [Xu and et al., J. Chem. Phys. 122, 244305 (2005)] with additional high-level ab initio points for the long-range interaction potential in the O+OH channel. Exact J=0 quantum mechanical reaction probabilities were calculated on the new potential and the rate constant for the title reaction was obtained using a J-shifting method. The calculated rate constant is in good agreement with available experimental values and our results predict a significantly lower rate at temperature range below 30K, offering a possible explanation for the “interstellar oxygen problem.”
Schottky barrier characteristics and interfacial reactions of Ti on n-In0.52Al0.48As
Authors: Wang Liang , Adesida Ilesanmi
Published: July 2007

Schottky barrier heights (ϕB) and ideality factors (n) of Ti∕Pt∕Au diodes on n-InAlAs were characterized. Transmission electron microscopy (TEM) investigations were utilized to correlate the electrical performance with interfacial reactions. The enhancement of ϕB and increase in n were obtained with increasing annealing temperatures. TEM studies confirmed that amorphous layers were formed at the Ti∕InAlAs interface at short annealing times, while prolonged annealing resulted in the crystallization of TiAs, defective layer formation, and Kirkendall void formation. Such aggressive reactions after prolonged annealing extended deep into the InAlAs and may affect the active region of InAlAs∕InGaAs-based transistors. The activation energy for this reaction was calculated to be 1.5±0.1eV.
Anisotropic electronic structure in quasi-one-dimensional K0.3MoO3: An angle-dependent x-ray absorption study
Authors: Tsai H. M. , Asokan K. , Pao C. W. , Chiou J. W. , Du C. H. , Pong W. F. , Tsai M.-H. , Jang L. Y.
Published: July 2007

The electronic structure of quasi-one-dimensional (quasi-1D) blue bronze, K0.3MoO3, was investigated by angle-dependent x-ray absorption near-edge structure (XANES) spectroscopy at O and K K and Mo L3 edges along the quasi-1D MoO6 octahedron-chain direction, i.e., the b axis, and the octahedron-in-plane direction, i.e., the d axis, well below its Peierls phase transition temperature (180K). The O K-edge XANES spectra indicate that the angle dependence of O 2p–Mo 4d hybridization, especially those with the π* character, is more significant along the b axis than along the d axis. Similar trend is also observed in the Mo L3-edge XANES spectra. The K K-edge XANES spectra reveal anisotropic effect of hybridization of K 4p states with O 2p states on the MoO6 octahedron.
Defects in hydrothermally grown bulk ZnO
Authors: von Wenckstern H. , Schmidt H. , Grundmann M. , Allen M. W. , Miller P. , Reeves R. J. , Durbin S. M.
Published: July 2007

Hydrothermally grown bulk ZnO (Tokyo Denpa) was investigated using junction-capacitance spectroscopy on silver oxide Schottky contacts (barrier height of 1.20eV, ideality factor of 1.04). Two main shallow defects, T1 and T2, with thermal activation energies of 13 and 52meV, respectively, were identified. Two closely lying, deep defect levels E3∕E3′ at approximately 320meV below the conduction band were found in higher concentrations (mid-1014cm−3) than the shallow donors. 4K photoluminescence showed dominant emission from excitons bound to three neutral donors, aluminum, hydrogen, and an unassigned impurity, with donor binding energies close to the thermal activation energy of T2.
Multiferroic properties of Bi0.87La0.05Tb0.08FeO3 ceramics prepared by spark plasma sintering
Authors: Jiang Q. H. , Ma J. , Lin Y. H. , Nan Ce-Wen , Shi Z. , Shen Z. J.
Published: July 2007

Dense Bi0.87La0.05Tb0.08FeO3 ceramics were prepared by spark plasma sintering. The sample showed stable dielectric constant and low dielectric loss (∼5%), and a saturation ferroelectric loop with remnant polarization of 17μC∕cm2 and saturation polarization of 19μC∕cm2, as well as good ferromagnetism with saturation magnetization of 0.71emu∕g, at room temperature. After the sample was poled, its piezoelectric constant was measured as 12.8pC∕N, and, in particular, an obvious magnetoelectric coupling was observed.
Selective induction of chemotherapy resistance of mammary tumors in a conditional mouse model for hereditary breast cancer
Authors: Rottenberg Sven , Nygren Anders O. H. , Pajic Marina , van Leeuwen Fijs W. B. , van der Heijden Ingrid , van de Wetering Koen , Liu Xiaoling , de Visser Karin E. , Gilhuijs Kenneth G. , van Tellingen Olaf , Schouten Jan P. , Jonkers Jos , Borst Piet
Published: July 2007

We have studiedin vivoresponses of “spontaneous”Brca1- andp53-deficient mammary tumors arising in conditional mouse mutants to treatment with doxorubicin, docetaxel, or cisplatin. Like human tumors, the response of individual mouse tumors varies, but eventually they all become resistant to the maximum tolerable dose of doxorubicin or docetaxel. The tumors also respond well to cisplatin but do not become resistant, even after multiple treatments in which tumors appear to regrow from a small fraction of surviving cells. Classical biochemical resistance mechanisms, such as up-regulated drug transporters, appear to be responsible for doxorubicin resistance, rather than alterations in drug-damage effector pathways. Our results underline the promise of these mouse tumors for the study of tumor-initiating cells and of drug therapy of human cancer.
Somatic loss of BRCA1 and p53 in mice induces mammary tumors with features of human
BRCA1
-mutated basal-like breast cancer
Authors: Liu Xiaoling , Holstege Henne , van der Gulden Hanneke , Treur-Mulder Marcelle , Zevenhoven John , Velds Arno , Kerkhoven Ron M. , van Vliet Martin H. , Wessels Lodewyk F. A. , Peterse Johannes L. , Berns Anton , Jonkers Jos
Published: July 2007

Women carrying germ-line mutations in
BRCA1
are strongly predisposed to developing breast cancers with characteristic features also observed in sporadic basal-like breast cancers. They appear as high-grade tumors with high proliferation rates and pushing borders. On the molecular level, they are negative for hormone receptors and ERBB2, display frequent TP53 mutations, and express basal epithelial markers. To study the role of BRCA1 and P53 loss of function in breast cancer development, we generated conditional mouse models with tissue-specific mutation of
Brca1
and/or
p53
in basal epithelial cells. Somatic loss of both BRCA1 and p53 resulted in the rapid and efficient formation of highly proliferative, poorly differentiated, estrogen receptor-negative mammary carcinomas with pushing borders and increased expression of basal epithelial markers, reminiscent of human basal-like breast cancer. BRCA1- and p53-deficient mouse mammary tumors exhibit dramatic genomic instability, and their molecular signatures resemble those of human
BRCA1
-mutated breast cancers. Thus, these tumors display important hallmarks of hereditary breast cancers in
BRCA1
-mutation carriers.
Varenicline, an α4β2 nicotinic acetylcholine receptor partial agonist, selectively decreases ethanol consumption and seeking
Authors: Steensland Pia , Simms Jeffrey A. , Holgate Joan , Richards Jemma K. , Bartlett Selena E.
Published: July 2007

Alcohol dependence is a disease that impacts millions of individuals worldwide. There has been some progress with pharmacotherapy for alcohol-dependent individuals; however, there remains a critical need for the development of novel and additional therapeutic approaches. Alcohol and nicotine are commonly abused together, and there is evidence that neuronal nicotinic acetylcholine receptors (nAChRs) play a role in both alcohol and nicotine dependence. Varenicline, a partial agonist at the α4β2 nAChRs, reduces nicotine intake and was recently approved as a smoking cessation aid. We have investigated the role of varenicline in the modulation of ethanol consumption and seeking using three different animal models of drinking. We show that acute administration of varenicline, in doses reported to reduce nicotine reward, selectively reduced ethanol but not sucrose seeking using an operant self-administration drinking paradigm and also decreased voluntary ethanol but not water consumption in animals chronically exposed to ethanol for 2 months before varenicline treatment. Furthermore, chronic varenicline administration decreased ethanol consumption, which did not result in a rebound increase in ethanol intake when the varenicline was no longer administered. The data suggest that the α4β2 nAChRs may play a role in ethanol-seeking behaviors in animals chronically exposed to ethanol. The selectivity of varenicline in decreasing ethanol consumption combined with its reported safety profile and mild side effects in humans suggest that varenicline may prove to be a treatment for alcohol dependence.
Effective transport properties for diffusion in random media
Authors: Dean D S , Drummond I T , Horgan R R
Published: July 2007

Results on the calculation of the long time self-diffusion constant of a Brownian particle in
a random environment are reviewed. We concentrate on the case of diffusion in a force
field generated by a quenched random potential and the case of diffusion in an
environment with a quenched, spatially varying, random diffusivity. Mathematical
relations between these two problems and exact results in low dimensions are
discussed as well as approximative perturbation schemes for these computations.
Numerical techniques used in the simulation of these systems are also discussed.
Tropical discriminants
Authors: Dickenstein Alicia , Feichtner Eva , Sturmfels Bernd
Published: July 2007

Tropical geometry is used to develop a new approach to the theory of discriminants and resultants in the sense of Gel

′

’

fand, Kapranov and Zelevinsky. The tropical

A
A

-discriminant is the tropicalization of the dual variety of the projective toric variety given by an integer matrix

A
A

. This tropical algebraic variety is shown to coincide with the Minkowski sum of the row space of

A
A

and the tropicalization of the kernel of

A
A

. This leads to an explicit positive formula for all the extreme monomials of any

A
A

-discriminant.
The module structure of a group action on a polynomial ring: A finiteness theorem
Authors: Karagueuzian Dikran , Symonds Peter
Published: July 2007

Consider a group acting on a polynomial ring over a finite field. We study the polynomial ring as a module for the group and prove a structure theorem with several striking corollaries. For example, any indecomposable module that appears as a summand must also appear in low degree, and so the number of isomorphism types of such summands is finite. There are also applications to invariant theory, giving a priori bounds on the degrees of the generators.
An infinite dimensional affine nil algebra with finite Gelfand-Kirillov dimension
Authors: Lenagan T. , Smoktunowicz Agata
Published: July 2007

The famous 1960’s construction of Golod and Shafarevich yields infinite dimensional nil, but not nilpotent, algebras. However, these algebras have exponential growth. Here, we construct an infinite dimensional nil, but not locally nilpotent, algebra which has polynomially bounded growth.
Gleevec Increases Levels of the Amyloid Precursor Protein Intracellular Domain and of the Amyloid-β–degrading Enzyme Neprilysin
Authors: Eisele Yvonne S. , Baumann Matthias , Klebl Bert , Nordhammer Christina , Jucker Mathias , Kilger Ellen
Published: July 2007

Amyloid-β (Aβ) deposition is a major pathological hallmark of Alzheimer's disease. Gleevec, a known tyrosine kinase inhibitor, has been shown to lower Aβ secretion, and it is considered a potential basis for novel therapies for Alzheimer's disease. Here, we show that Gleevec decreases Aβ levels without the inhibition of Notch cleavage by a mechanism distinct from γ-secretase inhibition. Gleevec does not influence γ-secretase activity in vitro; however, treatment of cell lines leads to a dose-dependent increase in the amyloid precursor protein intracellular domain (AICD), whereas secreted Aβ is decreased. This effect is observed even in presence of a potent γ-secretase inhibitor, suggesting that Gleevec does not activate AICD generation but instead may slow down AICD turnover. Concomitant with the increase in AICD, Gleevec leads to elevated mRNA and protein levels of the Aβ-degrading enzyme neprilysin, a potential target gene of AICD-regulated transcription. Thus, the Gleevec mediated-increase in neprilysin expression may involve enhanced AICD signaling. The finding that Gleevec elevates neprilysin levels suggests that its Aβ-lowering effect may be caused by increased Aβ-degradation.
Ontogenetic and spatial variation in the diet of hake (Merluccius merluccius) in the Bay of Biscay and the Celtic Sea
Authors: Mahe K. , Amara R. , Bryckaert T. , Kacher M. , Brylinski J. M.
Published: July 2007

Mahe, K., Amara, R., Bryckaert, T., Kacher, M., and Brylinski, J. M. 2007. Ontogenetic and spatial variation in the diet of hake (Merluccius merluccius) in the Bay of Biscay and the Celtic Sea. – ICES Journal of Marine Science, 64: 1210–1219. Analysis of the diet of trawl-caught hake (Merluccius merluccius) from three locations in the Bay of Biscay and the Celtic Sea in autumn 2001 showed that small hake fed almost exclusively on crustaceans (mainly euphausiids), but that there was a significant shift towards a fully piscivorous diet in hake >23 cm. A change in fish prey was also size-dependent, because smaller hake (<30 cm) preyed on small pelagic fish (3–12 cm), such as horse mackerel, anchovy, and pilchard, and larger hake on larger demersal prey (12–23 cm), such as blue whiting. There was a significant positive relationship between hake and fish prey length. In terms of fish prey selectivity, hake exhibited particular preference for small pelagic prey (anchovy, pilchard, and argentine) and for other hake. The diet did not generally reflect fish prey availability. Although horse mackerel and blue whiting were the two most abundant fish prey species in the environment, they were not positively selected by hake. Cannibalism accounted for a non-negligible part of the diet and was observed mainly in large hake (>30 cm). For all sizes analysed, conspecifics constituted 19.2%W of the diet and the frequency of occurrence of hake in the stomachs was 10.53%. Most hake prey were 0-group juveniles (<20 cm). Hake cannibalism appeared to be influenced mainly by the abundance of juveniles and the overlap between distribution patterns of juveniles and adults.
Resistance of Sharon Goatgrass (Aegilops sharonensis) to Fungal Diseases of Wheat
Authors: Olivera P. D. , Kolmer J. A. , Anikster Y. , Steffenson B. J.
Published: July 2007

Sharon goatgrass (Aegilops sharonensis) is a wild relative of wheat that is native to Israel and Lebanon. The importance of A. sharonensis as a source of new resistance genes for wheat warrants additional research on the characterization of accessions for economically important genes. Thus, the objectives of this study were to evaluate a collection of A. sharonensis accessions for resistance to seven important fungal diseases of wheat and assess the phenotypic diversity of the germplasm for disease reaction. The frequency of resistance in A. sharonensis was highest to powdery mildew (79 to 83%) and leaf rust (60 to 77%). Resistance to stem rust also was common, although the percentage of resistant accessions varied markedly depending on the pathogen race—from 13% to race TTTT to 72% to race QCCJ. The frequency of resistance was intermediate to stripe rust (45%) and low to tan spot (15 to 29%) and spot blotch (0 to 34%). None of the A. sharonensis accessions was resistant to Fusarium head blight. Many of the accessions tested exhibited heterogeneous reactions (i.e., had both resistant and susceptible plants) to one or more of the diseases, suggesting that heterozygosity may be present at some resistance loci. Substantial variation was observed in the level of diversity to individual diseases because Shannon's Equitability index ranged from 0.116 (for Fusarium head blight) to 0.994 (for tan spot). A high level of diversity was found both between and within collection sites. Moreover, differences in the geographic distribution of resistant accessions were observed. For example, accessions from northern Israel generally were less diverse and less resistant to leaf rust and stripe rust than accessions from more southern locations. Four A. sharonensis accessions were highly resistant to most of the diseases evaluated and may provide a source of unique resistance genes for introgression into cultivated wheat.
Effects of Tillage Practices on Dissemination and Spatial Patterns of Heterodera glycines and Soybean Yield
Authors: Gavassoni W. L. , Tylka G. L. , Munkvold G. P.
Published: July 2007

Two field experiments were conducted in central Iowa to assess the effects of tillage on Heterodera glycines dissemination and reproduction and soybean (Glycine max) yield. Plots in both experiments were artificially infested with equivalent numbers of H. glycines cysts. In one experiment, plots were left noninfested or received aggregated or uniform infestation, and a susceptible soybean cultivar was grown for 3 years. By the end of the first growing season and through the second, H. glycines population densities were consistently greater (P ≤ 0.05) in uniformly infested plots than in plots with aggregated infestations. No differences in soybean yield among the treatments were detected. In a second experiment, a 1-m2 area of each plot was infested with H. glycines cysts, susceptible soybeans were grown for four seasons, and crop residue was managed with either ridge-, conventional-, reduced-, or no-tillage. After 1 year, nematode population densities were significantly (P ≤ 0.05) greater in conventional- and reduced-tillage treatments than in no- and ridge-tillage treatments. After 2 years, H. glycines had been disseminated 6.9 m from the infestation site in conventional- and reduced-tillage treatments but only 0.5 and 1.4 m for no-tillage and ridge-tillage treatments, respectively. After 3 years, H. glycines population densities were 10 times greater in conventional- and reduced-tillage treatments than in the no-tillage treatment; conventional-tillage was the only treatment with yield significantly lower (P ≤ 0.05) than the noninfested control. Aggregation of H. glycines eggs was greater (P ≤ 0.05) in no- and ridge-tillage treatments than in conventional- and reduced-tillage treatments. Results indicate tillage can quickly disseminate H. glycines in newly infested fields, facilitating more rapid nematode reproduction and subsequent yield loss.
Resistance to Phytophthora infestans in Lycopersicon pennellii
Authors: Smart Christine D. , Tanksley Steven D. , Mayton Hilary , Fry William E.
Published: July 2007

To determine if the desert tomato, Lycopersicon pennellii, possesses resistance to late blight, caused by Phytophthora infestans, two plant populations were analyzed. Resistance was identified through assessments of disease progress in an F2 mapping population (L. esculentum × L. pennellii) and in a series of introgression lines (L. pennellii into L. esculentum). Levels of resistance varied widely among individuals within each population. However, the response of individuals to different strains of P. infestans was consistent. In the mapping population, a quantitative trait locus (QTL) was detected near marker T1556 on chromosome 6. This QTL accounted for 25% of the phenotypic variance in the population. The occurrence of this QTL was confirmed from analysis of the introgression lines (ILs), where IL 6-2 (containing marker T1556) was the most resistant IL in 2002 and the second most resistant IL in 2001. The identification of an additional QTL for resistance to late blight in tomato will aid in the development of durable resistance to this devastating disease.
Nested-PCR Detection and Sequence Confirmation of ‘Candidatus Liberibacter asiaticus’ from Murraya paniculata in Guangdong, China
Authors: Deng X. , Zhou G. , Li H. , Chen J. , Civerolo E. L.
Published: July 2007

Murraya paniculata (orange jasmine) is a popular ornamental rutaceaous plant and is known to be a preferred host for the Asian citrus psyllid, Diaphorina citri (Kuwayana), the primary vector of ‘Candidatus Liberibacter spp.’ that causes citrus Huanglongbing (HLB). HLB is a highly destructive citrus disease worldwide. However, the presence of ‘Ca. Liberibacter spp.’ in M. paniculata remains uncertain (2). Clarification of M. paniculata as a host of ‘Ca. Liberibacter spp.’ has direct impact on HLB control programs. During June of 2006, we identified three M. paniculata trees near a mandarin orchard affected by HLB in Luoding City and two trees from Guangzhou City, Guangdong Province, People's Republic of China. All trees had leaves showing yellowing and mottling symptoms characteristic of HLB. Both symptomatic and asymptomatic leaves were collected. DNA was extracted using the CTAB (cetyltrimethylammoniumbromide) method and assayed by nested-PCR. The general bacterial 16S rDNA primer set fDl/rD1 (3) was used for the first round of amplification. Amplification was conducted as previously described (1), and 2 μl of PCR reaction product were used for a second round of amplification using the same procedure but with 35 PCR cycles with primer set OI1/OI2c (3,4). After agarose gel electrophoresis and staining with ethidium bromide, a 1.1-kb DNA band was unambiguously associated with symptomatic but not asymptomatic leaf samples. Nonnested-PCR using primer set OI1/OI2c alone did not yield a target DNA band or yielded a very weak DNA band. XbaI digestion of the nested-PCR DNA product yielded two fragments, 520 and 640 bp long, characteristic of ‘Ca. L. asiaticus’. PCR amplicons were sequenced and were 1,095 bp long. This sequence shared >98% similarity to sequences of ‘Ca. L. asiaticus’ in the GenBank database. We observed that nested-PCR is necessary for consistent amplification of DNA from ‘Ca. L. asiaticus’ from M. paniculata. We excluded the possible nonspecific amplification associated with nested-PCR by XbaI restriction enzyme digestion and by nucleotide sequence analysis. Our data indicate that M. paniculata is a host of ‘Ca. L. asiaticus’ but the bacterial titer might be low.

References: (1) X. Deng et al. Online publication. doi:10.1094/PHP-2007-0419-01-BR. Plant Health Progress, 2007. (2) M. Garnier and J. Bove. Huanglongbing (Greening). Page 46 in: Compendium of Citrus Diseases. 2nd ed. L. W. Timmer et al., eds. The American Phytopathological Society, St. Paul, MN, 2000. (3) S. Jagoueix et al. Int. J. Syst. Bacteriol. 44:379, 1994. (4) S. Jagoueix et al. Mol. Cell. Probes 10:43, 1996.
First Report of Citrus leaf blotch virus on Kumquat in Italy
Authors: Guardo M. , Sorrentino G. , Marletta T. , Caruso A.
Published: July 2007

During the spring of 2006, nurserymen reported observations of the bud union disorder of ‘Nagami’ kumquat scions propagated on Troyer citrange rootstock to the CRA–Istituto Sperimentale per l'Agrumicoltura. These plants showed reduced canopy volume and new shoots below graft points 6 months after propagation; the bud union was brittle and broke down easily after 1 year. After tests excluded common citrus viruses and viroids that might cause the incompatibility (e.g., Citrus tristeza virus, Citrus psorosis virus, Citrus exocortis viroid, and Hop stunt viroid), we tested for Citrus leaf blotch virus (CLBV), a virus previously associated with a bud union crease in kumquat (2). Leaves were collected from 100 2-year-old kumquat plants from a nursery near Messina (Sicily [Italy]); 50 were grafted on sour orange rootstock (asymptomatic) and 50 were grafted on Troyer citrange rootstock (symptomatic). Total RNA was extracted using Qiagen RNeasy Plant Mini Kit (Qiagen S.P.A. Milan, Italy). Primers previously reported (1,2) and designed from a published CLBV sequence (Genbank Accession No. AJ318061) were used in reverse transcription (RT)-PCR assays to amplify the RNA-dependent RNA polymerase gene (sense primer KU 27, 5′-GATGCAAGCCAGGATGAATAC-3′, genomic positions 5321–5340 and anti-sense primer KU 15, 5′-CAGACACTCCAAGACCTTTCC-3′, genomic positions 5776–5756) and the coat protein gene (sense primer KU18, 5′-TTAAGATTACAGACACGAAGG-3′ genomic positions 7686–7706 and anti-sense primer KU 19 5′-CTGTTTTTGAATTTTGCTCG-3′, genomic positions 8123–8104). All kumquat samples yielded amplicons of the expected size (456 and 438 bp). No amplicons were obtained from healthy plants. Amplicons for each gene were cloned into the pGEM-T Easy Vector (Promega Italy, Milan), and four clones for each plasmid DNA were sequenced in both directions. Consensus sequences of the two genes (Genbank Accession Nos. EF203229 and EF203230) had 96 and 97% nucleotide sequence identity, respectively, and both had 99% amino acid identity with the previously reported CLBV sequence (Genbank Accession No. AJ318061). Approximately 400,000 ornamental kumquats are produced annually in Italy. CLBV infection can cause serious production losses because of the decline associated with bud union disorders grafted onto trifoliate orange and trifoliate-derived rootstocks.

References: (1) L. Galipienso et al. Eur. J. Plant Pathol. 110:175, 2004. (2) M. C. Vives et al. Virology 287:225, 2001.
First Report of a Phytoplasma Affecting Tomato in Poland
Authors: Pospieszny H. , Krawczyk K. , Kamasa J. , Petrzik K.
Published: July 2007

During 2006, two tomato plants exhibiting dwarfing, twisting of shoots and leaves, and virescence and phyllody of flowers were observed in a greenhouse in western Poland. Total genomic DNA was extracted from approximately 3.5 g of leaf midribs and petioles using the modified cetyltrimethylammoniumbromide (CTAB) buffer method (3). Direct PCR was done with universal phytoplasma primers P1/P7 for amplification of ribosomal 16S rDNA. The PCR product (1.8 kb) was diluted 1:30 with sterile distilled water and used as DNA template for nested PCR with primers R16F2n/R16R2 (1). The final product was an expected 1.2-kb rDNA fragment amplified from infected tomato tissues. The DNA extracted from a Vinca sp. infected with phytoplasma of 16SrI-B subgroup and from a healthy tomato plant were used as positive and negative assay controls, respectively. Restriction fragment length polymorphism analysis of the final PCR product (1.2 kb) using enzymes MseI, KpnI, AluI, HhaI, HpaII, RsaI, TaqI, and TruI (1) indicated that phytoplasma from the tomato belonged to the subgroup 16SrI-C (1,2). The sequence obtained from the final PCR product (746 bp) was deposited in the GenBank database under accession number EF164961. Multiple sequence alignments with sequences of phytoplasma available from GenBank were performed using ClustalW software. The analysis revealed that the Polish isolate was co-identical (100%) to two phytoplasma sequences (GenBank Accession Nos. AY839617 and DQ078304) that belong to 16SrI-C subgroup. To our knowledge, this is the first report of a phytoplasma affecting tomato plant in Poland.

References: (1) I.-M. Lee et al. Inst. J. Syst. Bacteriol. 48:1153, 1998. (2) I.-M. Lee et al. Cell-wall free bacteria. Page 283 in: Laboratory Guide for Identification of Plant Pathogenic Bacteria. 3rd ed. N. W. Schaad et a.l, eds. The American Phytopathology Society, 2001. (3) A. C. Padovan et al. Austral. J. Grape Wine Res. 1:25, 1995.
Squash vein yellowing virus Identified in Watermelon (Citrullus lanatus) in Indiana
Authors: Egel D. S. , Adkins S.
Published: July 2007

During September 2006, moderate vine decline symptoms including vine collapse and wilt and root rot were observed on numerous watermelon plants growing in a commercial field in Sullivan County, Indiana. No symptoms were observed on the fruit. Six plants displaying typical vine decline symptoms were collected and assayed for potyvirus infection and subsequently for Squash vein yellowing virus (SqVYV) and Papaya ringspot virus type W (PRSV-W). SqVYV is a whitefly-transmitted member of the Potyviridae, recently shown to cause watermelon vine decline in Florida (1,4). Plants infected with SqVYV in Florida are also frequently infected with PRSV-W, although SqVYV is sufficient for watermelon vine decline. The six field samples harbored one or more potyviruses as determined by ELISA (Agdia, Elkhart, IN). Mechanical inoculation of squash (Cucurbita pepo) and watermelon with sap from three of the field samples induced mosaic symptoms in both that are typical of potyviruses. Vein yellowing in squash and plant death in watermelon typical of SqVYV (1) later developed in plants inoculated with one field sample. A coat protein gene fragment was amplified by reverse transcription (RT)-PCR with SqVYV primers (1) from total RNA of five of the six field samples and also from the symptomatic, inoculated plants. Nucleotide and deduced amino acid sequences of a 957-bp region of the RT-PCR product (primer sequences deleted prior to analysis) were 100% identical to SqVYV (GenBank accession No. DQ812125). PRSV-W also was identified in two of the five SqVYV-infected field samples by ELISA (Agdia) and by sequence analysis of a 3′ genome fragment amplified by RT-PCR with previously described degenerate potyvirus primers (3). No evidence for infection by other potyviruses was obtained. To our knowledge, this is the first report of SqVYV in Indiana and the first report of the virus anywhere outside of Florida. The whitefly (Bemisia tabaci, B strain) vector of SqVYV is relatively uncommon in Indiana and the cold winter temperatures make it unlikely that any SqVYV-infected watermelon vines or whiteflies will overseason, necessitating reintroductions of virus and vector each season. We feel that the moderate and restricted occurrence of SqVYV in Indiana observed in September 2006 should pose little or no threat to commercial watermelon production in Indiana and should not cause growers to alter their growing practices. The occurrence of SqVYV in Indiana does not appear to explain the similar symptoms of mature watermelon vine decline (MWVD) that has been observed in Indiana since the 1980s. In contrast with the insect vectored SqVYV, MWVD seems to be caused by a soilborne biological agent (2).

References: (1) S. Adkins et al. Phytopathology 97:145, 2007. (2) D. S. Egel et al. Online publication. doi:10.1094/PHP-2000-1227-01-HN. Plant Health Progress, 2000. (3) A. Gibbs and A. Mackenzie. J. Virol. Methods 63:9, 1997. (4) P. Roberts et al. Citrus Veg. Mag. December 12, 2004.
Shoot Blight Caused by Diplodia pinea on Afghan and Austrian Pines in Texas
Authors: Ong K. , Hill S. , Smith D. R. , Stanosz G. R.
Published: July 2007

Shoot blight was observed on ornamental Afghan (Pinus eldarica) and Austrian pines (P. nigra) at several sites in metropolitan Dallas, TX in the summer of 2005. Shoots were stunted, cankered, often resinous, sometimes curled or crooked at the tips, and bore brown needles that often had been killed before full elongation. Pycnidia on necrotic needles, stems, and cones of each host species yielded conidia characteristic of the fungus Diplodia pinea. Individual conidia and hyphal tip transfers produced pure cultures confirmed as D. pinea using a species-specific PCR assay (1), which allows differentiation from the similar pine shoot blight pathogen D. scrobiculata. Five isolates (three from Afghan pine and two from Austrian pine) were tested for pathogenicity by inoculation of potted 1-year-old Afghan pine seedlings obtained from the Texas Forest Service Nursery. Elongating terminal shoots were wounded by removing a needle pair approximately 2 cm below the shoot apex. A 4-mm-diameter plug cut from an actively growing culture on water agar (WA) was placed fungus side down on the wound. Noncolonized WA plugs were placed on similarly wounded control seedlings. Nonwounded control seedlings also were used. Parafilm was wrapped around the shoots to hold the agar plugs in place and was removed 2 weeks later. Each treatment was applied to four seedlings. Five weeks after inoculation, 9 of the 20 inoculated seedlings (including at least one inoculated with each isolate) exhibited dieback of shoot tips. One wounded control seedling exhibited slight tip dieback, no other nonwounded or wounded control seedlings developed symptoms. Segments of shoots were harvested, surface disinfested, and incubated on WA to determine the presence of the pathogen. The pathogen was reisolated from 11 of the 20 inoculated seedlings but not from any control seedlings. To our knowledge, this is the first report of D. pinea as a cause of shoot blight of Afghan pine and the first substantiated report of the occurrence of D. pinea in Texas. Although widely distributed in much of eastern North America, reports of the presence of D. pinea in the other southern gulf coast states of Alabama, Louisiana, and Mississippi, as well as the western states of Colorado, New Mexico, and Utah, are lacking.

Reference: (1) D. R. Smith and G. R. Stanosz. Plant Dis. 90:307, 2006.
First Report of Soybean Rust Caused by Phakopsora pachyrhizi in Ghana
Authors: Bandyopadhyay R. , Ojiambo P. S. , Twizeyimana M. , Asafo-Adjei B. , Frederick R. D. , Pedley K. F. , Stone C. L. , Hartman G. L.
Published: July 2007

Nigeria is the only country in West Africa where soybean rust, caused by Phakopsora pachyrhizi, has been officially reported (1). During a disease survey in Ghana during October 2006, soybean (Glycine max) leaves with rust symptoms (tan, angular lesions with erumpent sori exuding urediniospores) were observed in 11 fields in the following districts: Kassena Nankana in the Upper East Region; East Gonja, Central Gonja, and Tolon-Kumbungu in the Northern Region; and Ejisu-Juabeng in the Ashanti Region. Disease incidence in these fields ranged from 50 to 100% and disease severity ranged between 3 and 40% of the leaf area on infected plants. Urediniospores were hyaline, minutely echinulate, and 23 to 31 × 14 to 18 μm. Within a week of collection, leaf samples were sent to the USDA-ARS Foreign Disease-Weed Science Research Unit for verification of pathogen identity. DNA was extracted from leaf pieces containing sori with the Qiagen DNeasy Plant Mini kit (Valencia, CA), and all 11 field samples amplified in a real-time fluorescent PCR with the P. pachyrhizi-specific primers Ppm1 and Ppa2 (2). Sequence alignment of the internal transcribed spacer (ITS) region 2 further confirmed the identification as P. pachyrhizi (2). Infected leaves from three fields were separately washed in sterile water to collect urediniospores that were used to separately inoculate three detached leaves (for each isolate) of susceptible cultivar TGx 1485-1D (3). The abaxial surface of detached leaves was sprayed with 400 μl of spore suspension (1 × 106 spores per ml). A single leaf piece was placed in a 9-cm-diameter petri dish with adaxial side appressed on 1% technical agar amended with 10 μg/ml of kinetin. Lactic acid (1.5 ml/liter) and benomyl (12.5 mg/liter) were added to the agar medium to inhibit growth of saprophytic fungi and bacteria. Petri dishes were incubated at 20°C with a 12-h light/12-h dark cycle. Lesions on inoculated leaves developed 5 to 6 days after inoculation (DAI), and pustules (105 to 120 μm) formed 7 to 8 DAI and erupted 3 days later exuding columns of urediniospores similar in size to the initially collected isolates. Inoculating another set of detached leaves with a spore suspension (1 × 106 spores per ml) from the first set of detached leaves resulted in typical rust symptoms. The PCR assay, alignment of ITS region 2, morphological characters of the isolates, and pathogenicity tests demonstrate that P. pachyrhizi occurs in Ghana. To our knowledge, this is the first report of P. pachyrhizi in Ghana.

References: (1) O. A. Akinsanmi et al. Plant Dis. 85:97, 2001. (2) R. D. Frederick et al. Phytopathology 92:217, 2002. (3) M. Twizeyimana et al. Online publication. http://www.plantmanagementnetwork.org/ infocenter/topic/soybeanrust/2006/posters/41.asp. Plant Management Network, 2006.
First Report of Tomato torrado virus in Tomato in the Canary Islands, Spain
Authors: Alfaro-Fernández A. , Córdoba-Sellés C. , Cebrián M. C. , Sánchez-Navarro J. A. , Espino A. , Martín R. , Jordá C.
Published: July 2007

In 2003, greenhouse-grown tomato crops (Lycopersicon esculentum Mill.) in the Canary Islands (Spain) were observed showing an initial yellowing in defined areas at the base of the leaflet that later developed into necrotic spots or an extensive necrotic area progressing from the base to tip. Fruits were also affected, showing necrotic areas and often developing cracking. Generally, the plants that were affected seemed to be burnt, their growth was reduced, and the production level was seriously damaged. Similar symptoms have been observed in Murcia (Spain) since 2001, which have been recently associated with Tomato torrado virus (ToTV) infection (2). Twenty-two tomato samples showing “torrado disease” symptoms were collected from different greenhouses between 2003 and 2006 in Las Palmas (Canary Islands, Spain). To verify the identity of the disease, double-antibody sandwich (DAS)-ELISA was performed on leaf and fruit extracts of symptomatic plants using polyclonal antibodies specific to Potato virus Y (PVY), Tomato mosaic virus (ToMV), Tomato spotted wilt virus (TSWV) (Loewe Biochemica, Sauerlach, Germany), and Pepino mosaic virus (PepMV) (DSMZ, Braunschweig, Germany). Total RNA was extracted from the 22 tomato samples with the RNAwiz Extraction kit (Ambion, Huntingdon, United Kingdom) and tested using one-step reverse-transcription (RT)-PCR with the SuperScript Platinum Taq kit (Invitrogen Life Technologies, Barcelona, Spain) with primers specific to PepMV (1) and ToTV (2). All analyses included healthy tomato plants as negative controls. Five of the twenty-two tomato samples were positive for PepMV and negative for the other viruses tested by serological analysis. However, all 22 samples were positive in RT-PCR performed with the primers specific to ToTV segment RNA2. The RT-PCR assay to detect ToTV produced an amplicon of the expected size (580 bp). No amplification product was observed when healthy plants or a water control were used as a template in the RT-PCR reaction. The ToTV RT-PCR product was purified (High Pure PCR Product Purification kit, Roche Diagnostics, Mannheim, Germany) and sequenced. BLAST analysis of one sequence (GenBank Accession No. EF436286) showed 99% identity to ToTV RNA2 sequence (GenBank Accession No. DQ388880). To our knowledge, this is the first report of ToTV in the Canary Islands.

References: (1) I. Pagán et al. Phytopathology 96:274, 2006. (2) M. Verbeek et al. Online Publication. doi:10.1007/s00705-006-0917-6. Arch. Virol., 2007.
Investigating the catch returns and growth rate of wels catfish, Silurus glanis, using mark–recapture
Authors: Britton J. R. , Pegg J. , Sedgwick R. , Page R.
Published: July 2007

Abstract In January 2004, 46 wels catfish, Silurus glanis L., between 51 and 135 cm total length were tagged and released into a 0.4 ha recreational, catch and release, lake fishery in the UK, and their recapture by anglers monitored throughout the year. Of the 46 tagged fish, 16 were recaptured by anglers during 170 capture events. Some individual fish were captured up to 26 times. Catfish <75 cm appeared to be the least susceptible to capture and fish >100 cm most susceptible. Frequency of captures increased with temperatures >10 °C and peaked between June and August. Selected recapture weight data were used to produce a mass specific growth equation and revealed specific growth rate was a decreasing function of body mass over the size range of the recaptured fish. Their growth was slower than fish from elsewhere in their distribution range.
How do fish exploit temporary waters throughout a flooding episode?
Authors: Cucherousset J. , Carpentier A. , Paillisson J.‐M.
Published: July 2007

Abstract  Temporary waters are important habitats for many fish species. Nevertheless, determination of which species colonise these habitats, when this occurs and where fish distribute themselves within the temporary waters are rare. The fish assemblage on a temporarily flooded grassland and its adjacent permanent canal, together with environmental variables, were monitored throughout an entire flooding event from February to May 2006 in the Brière marsh (Northwest France). In total, 589 fish belonging to 12 species were captured, but the fish assemblage was dominated by six species in both habitats. Frequency of occurrence of fish was significantly higher in the canal than in the grassland (52.9 ± 11.9% and 13.0 ± 2.4%, respectively) and similar result was observed for relative density (1.72 ± 0.50 and 0.28 ± 0.08 fish per point sample, respectively). These parameters changed during the flooding event and maximum values were recorded in mid‐April, when proliferation of zooplankton and water temperature above 12 °C were observed. The extent of fish colonisation in the grassland was influenced by water level. During the first half of the flooding event, the proportion of grassland occupied by fish represented, on average, 45.9 ± 3.7% of the available flooded habitat. Afterwards, the extent of fish colonisation in the grassland decreased when water level decreased and fish used only 17.8 ± 2.1% of the available inundated area and remained close to the canal. A lack of synchronisation in the flood event and water temperature resulted in a mismatch between fish abundance and spatial distribution within the flooded grassland.