bluuebunny/crossref_metadata_2025 huggingface dataset:
Dependence of energy band offsets at Ge2Sb2Te5/SiO2 interface on nitrogen concentration
Authors: Fang Lina Wei-Wei , Zheng Zhang , Pan Ji-Sheng , Zhao Rong , Li Minghua , Shi Luping , Chong Tow-Chong , Yeo Yee-Chia
Published: February 2009

The electronic property for a series of nitrogen-doped Ge2Sb2Te5 phase change material was characterized using high-resolution x-ray photoelectron spectroscopy. The Te 3d5/2 and Si 2p core-level spectra as well as valence band spectra were used in the analysis. As the nitrogen content increases, the valence band offset also decreases, while that of the conduction band increases. Our results show that the valence band and conduction band offsets of nitrogen-doped Ge2Sb2Te5 on silicon oxide exhibit a linear dependence on nitrogen content in the film, for nitrogen content of up to 8.4 at. %.
Asymmetric intermediate reflector for tandem micromorph thin film silicon solar cells
Authors: Söderström T. , Haug F.-J. , Niquille X. , Terrazzoni V. , Ballif C.
Published: February 2009

The micromorph solar cell (stack of amorphous and microcrystalline cells) concept is the key for achieving high efficiency stabilized thin film silicon solar cells. We introduce a device structure that allows a better control of the light in-coupling into the two subcell components. It is based on an asymmetric intermediate reflector, which increases the effective thickness of the a-Si:H by a factor of more than three. Hence, the a-Si:H thickness reduction diminishes the light induced degradation, and micromorph tandem cells with 11.2% initial and 9.8% stabilized efficiencies (1000 h, 50 °C, and 100 mW/cm2) are made on plastic substrates with Tg<180 °C.
Increased frequency shifts in high aspect ratio terahertz split ring resonators
Authors: Chiam Sher-Yi , Singh Ranjan , Gu Jianqiang , Han Jiaguang , Zhang Weili , Bettiol Andrew A.
Published: February 2009

The resonance of split ring resonators (SRRs) is known to shift upon the addition of a dielectric overlayer, a feature useful for practical applications. Here, we demonstrate that the frequency shift is enlarged by increasing the SRR height, thereby potentially enhancing sensitivity and tunability. We fabricated SRRs resonating at terahertz frequencies using a focused proton beam. This resulted in SRRs nearly 10 μm high, with smooth and vertical sidewalls. Terahertz time domain spectroscopy was used for characterization. Upon applying a dielectric overlayer (ϵ=2.7), a resonance located at 640 GHz shifted by nearly 120 GHz. Simulations also indicate a widening frequency shift as SRR height increases.
Direct observation of oxygen induced room temperature ferromagnetism in MoO2 thin films by x-ray magnetic circular dichroism characterizations
Authors: Thakur P. , Cezar J. C. , Brookes N. B. , Choudhary R. J. , Prakash Ram , Phase D. M. , Chae K. H. , Kumar Ravi
Published: February 2009

We report the element specific polarized near edge x-ray absorption fine structure (NEXAFS) and x-ray magnetic circular dichroism (XMCD) experiments on well characterized undoped MoO2 thin films that show ferromagnetism at room temperature. The polarization dependent of O K edge NEXAFS spectra indicate a strong hybridization of O 2p-4d Mo orbitals followed by a strong anisotropy in the electronic properties. An unquenched orbital magnetic moment within the O 2p shell is clearly evident from the XMCD O K edge, which is ferromagnetically coupled to the neighboring Mo moments as confirmed by Mo M3,2 edge XMCD experiment.
Multimode laser emission from laterally confined organic microcavities
Authors: Sudzius M. , Langner M. , Hintschich S. I. , Lyssenko V. G. , Fröb H. , Leo K.
Published: February 2009

Room-temperature multimode laser emission is observed in a microcavity consisting of dielectric mirrors and small-molecular-weight organic photonic dots as a cavity layer. The structure shows simultaneous lasing of a wide variety of transverse modes. A comparison of the laser operating characteristics with those of unpatterned structures shows an enhancement in the spontaneous emission coupling factor by more than two orders of magnitude due to the lateral confinement. The spectral features are in quantitative agreement with calculations of quantized photonic states in three-dimensional optical cavities.
Adapting to climate change and managing climate risks by using real options
Authors: Hertzler Greg
Published: February 2009

Adapting to climate change and managing climate risks are new challenges for farmers, community leaders, and catchment management authorities. To meet this challenge, a new method of making decisions under risk may help. This method is called real options. It begins with common sense and adds rigour. It helps us decide when to keep our options open and when to foreclose options and create new ones. In this paper, real options are explained and applied to several examples by developing a new type of decision diagram. The diagrams are a language for thinking about complex decisions under risk. Farmers, community leaders, and catchment management authorities can develop similar diagrams and use them to communicate with other decision makers and with researchers. Finally, the decision diagrams are related to new mathematical tools to help find optimal decisions for managing climate risks.
Prediction of Tumour Tissue Diffusion Coefficients of Hypoxia-Activated Prodrugs from Physicochemical Parameters
Authors: Pruijn Frederik B. , Patel Kashyap , Hay Michael P. , Wilson William R. , Hicks Kevin O.
Published: February 2009

The therapeutic activity of anticancer agents depends critically on their ability to penetrate through tumour tissue to reach their target cells, a requirement that is especially important for hypoxia-activated prodrugs. Here we use multicellular layers (MCL) grown in vitro from HT29 colon carcinoma cells to measure tissue diffusion coefficients (Dmcl) of 67 structurally diverse benzotriazine di-N-oxides (analogues of the hypoxia-activated prodrug tirapazamine) plus four miscellaneous compounds. An algorithm was developed to predict Dmcl from physicochemical parameters (molecular weight, octanol/water partition coefficient at pH 7.4, number of hydrogen bond donors and acceptors); the fitted multivariate relationship had an explained variance (R2) of 0.907 and predictive power (Q2) of 0.879. Using a subset of nine compounds tested as a single cassette, the algorithm was shown to apply, with some adjustment of coefficients, to MCLs from three other tumour cell lines with differing cell packing densities (SiHa, HCT8-Ea, and HCT8-Ra). The demonstrated relationships provide tools for optimizing extravascular transport of anticancer agents during lead optimization.
Corrigendum to: 2-day versus 5-day famciclovir as treatment of recurrences of genital herpes: results of the FaST study
Authors: Bodsworth Neil , Bloch Mark , McNulty Anna , Denham Ian , Doong Nicholas , Trottier Sylvie , Adena Michael , Bonney Mary-Ann , Agnew James ,   the Australo-Canadian FaST (Famciclovir Short-Course Herpes Therapy) Study Group
Published: February 2009

Background: The brief period of viral replication in recurrent genital herpes lesions suggests shorter therapeutic regimens may be as effective as standard 5-day courses. Objective: To demonstrate that a 2-day course of famciclovir 500 mg statim, then 250 mg twice daily was non-inferior to the standard 5-day course of 125 mg twice daily. Methods: Patients were randomly assigned either the 2-day or 5-day famciclovir course and initiated therapy within 12 h of onset of prodromal symptoms. They were instructed to complete daily questionnaires on herpes-related symptoms and functioning and to attend the clinic for assessment of healing 5.5 days after initiating therapy. Results: A total of 873 patients were randomised at least once and 1038 recurrences were treated. The proportion of evaluable recurrences with lesions present at 5.5 days was less in the 2-day arm (24%) than in the 5-day (28%) arm. The upper 97.5% confidence limit (CL) for this difference in favour of the 2-day arm was 2% in favour of the 5-day arm, well within the 10% predefined for non-inferiority. The upper 97.5% CL was similar in the intent-to-treat, evaluable and per-protocol recurrence populations and when adjusted for baseline differences (in gender, age, herpes history and HIV infection) or for clustering of recurrences within patients. Both treatments had similar side-effects; proportion of lesions aborted; time to next recurrence; patient-reported symptoms; and impact on daily functioning. Conclusions: The 2-day course was as safe and effective as the standard 5-day course and can only enhance patient convenience and compliance.
Relationships between condoms, hormonal methods, and sexual pleasure and satisfaction: an exploratory analysis from the Women's Well-Being and Sexuality Study
Authors: Higgins Jenny A. , Hoffman Susie , Graham Cynthia A. , Sanders Stephanie A.
Published: February 2009

Background: Little is known about how condoms and other contraceptives influence women’s sexual enjoyment, which could shape use patterns. Methods: Data from an online study of women’s sexual health and functioning were used to examine how three categories of contraceptive use – hormonal method only, condoms primarily, and dual use – could help predict decreased sexual pleasure associated with contraceptive method and overall sexual satisfaction in the past 4 weeks. Results: In analyses controlling for age, relationship length, and other variables, male condoms were most strongly associated with decreased pleasure, whether used alone or in conjunction with hormonal methods. Women who used hormonal methods alone were least likely to report decreased pleasure, but they also had significantly lower overall scores of sexual satisfaction compared with the other two groups. Dual users, or women who used both condoms and a hormonal method, reported the highest sexual satisfaction scores. Conclusions: Because male condoms were viewed by many of these women as decreasing sexual pleasure, sexual risk practices are likely to be affected. Although hormonal only users were highly unlikely to report decreased pleasure, they reported lower sexual satisfaction compared with the other two groups. Dual users, who had the highest sexual satisfaction scores, may have been the most sexually satisfied because they felt more fully protected against unwanted pregnancy and sexually transmissible infections – consistent with previous qualitative documentation of ‘eroticising safety.’ This exploratory study suggests that different contraceptives affect sexuality in various ways, warranting further research into these sexual dimensions and how they influence contraceptive practices.
Correlates of parents' reports of acceptability of human papilloma virus vaccination for their school-aged children
Authors: de Visser Richard , McDonnell Elizabeth
Published: February 2009

Background: Routine human papilloma virus (HPV) vaccination for 12–13-year-old girls will be introduced in the UK from September 2008. The aim of the present study was to identify correlates of parents’ anticipated uptake of HPV vaccination for their sons and daughters. Methods: Self-administered questionnaires were completed by 353 parents of school-aged children living in Brighton and Hove (England). The main outcome measure was anticipated acceptance of HPV vaccination for children. Putative predictors of acceptance of HPV vaccination included general attitudes toward vaccination, beliefs about the impact on adolescent sexual behaviour of vaccines against sexually transmissible infections, and knowledge of HPV and cervical cancer. Results: Multivariate regression revealed that greater perceived benefits of HPV vaccination, greater general belief in the protection offered by vaccination, and greater support for adolescent sexual health services explained substantial proportions of the variance in HPV vaccine acceptability for both sons and daughters. For both sons and daughters, the most important correlate of vaccine acceptability was general belief in the protection offered by vaccination: this variable explained 40–50% of variance. Acceptability of vaccination appeared to improve following the provision of brief information about the links between HPV and cervical cancer and the proposed introduction of HPV vaccination. Conclusions: Uptake of HPV vaccination may be maximised by: improving attitudes toward the safety and efficacy of childhood vaccinations; countering concerns that provision of sexual health services for young people will encourage promiscuous or unsafe sexual behaviour; and improving knowledge about the role of HPV in cervical cancer aetiology.
Case report: lymphogranuloma venereum in New Zealand
Authors: Robertson Anne , Azariah Sunita , Bromhead Collette , Tabrizi Sepehr , Blackmore Timothy
Published: February 2009

We report New Zealand’s first two cases of anorectal lymphogranuloma venereum (LGV). Although infection in these cases was probably acquired off-shore, the cases are reported to demonstrate the need to be vigilant to the possibility of LGV when men who have sex with men present with symptoms of proctitis. Investigation and management of LGV is discussed.
Computer‐Aided Design of Nanocapsules for Therapeutic Delivery
Authors: Shreif Zeina , Ortoleva Peter
Published: February 2009

The design of nanocapsules for targeted delivery of therapeutics presents many, often seemingly self‐contradictory, constraints. An algorithm for predicting the physico‐chemical characteristics of nanocapsule delivery and payload release using a novel all‐atom, multiscale technique is presented. This computational method preserves key atomic‐scale behaviours needed to make predictions of interactions of functionalized nanocapsules with the cell surface receptors, drug, siRNA, gene or other payload. We show how to introduce a variety of order parameters with distinct character to enable a multiscale analysis of a complex system. The all‐atom formulation allows for the use of an interatomic force field, making the approach universal and avoiding recalibration with each new application. Alternatively, key parameters, which minimize the need for calibration, are also identified. Simultaneously, the methodology enables predictions of the supra‐nanometer‐scale behaviour, such as structural transitions and disassembly of the nanocapsule accompanying timed payload release or due to premature degradation. The final result is a Fokker–Planck equation governing the rate of stochastic payload release and structural changes and migration accompanying it. A novel “salt shaker” effect that underlies fluctuation‐enhancement of payload delivery is presented. Prospects for computer‐aided design of nanocapsule delivery system are discussed.
A Mathematical Model Quantifies Proliferation and Motility Effects of TGF‐β on Cancer Cells
Authors: Wang Shizhen Emily , Hinow Peter , Bryce Nicole , Weaver Alissa M. , Estrada Lourdes , Arteaga Carlos L. , Webb Glenn F.
Published: February 2009

Transforming growth factor (TGF)‐β is known to have properties of both a tumour suppressor and a tumour promoter. While it inhibits cell proliferation, it also increases cell motility and decreases cell–cell adhesion. Coupling mathematical modelling and experiments, we investigate the growth and motility of oncogene‐expressing human mammary epithelial cells under exposure to TGF‐β. We use a version of the well‐known Fisher–Kolmogorov equation, and prescribe a procedure for its parametrisation. We quantify the simultaneous effects of TGF‐β to increase the tendency of individual cells and cell clusters to move randomly and to decrease overall population growth. We demonstrate that in experiments with TGF‐β treated cells in vitro, TGF‐β increases cell motility by a factor of 2 and decreases cell proliferation by a factor of 1/2 in comparison with untreated cells.
Correlation between Animal and Mathematical Models for Prostate Cancer Progression
Authors: Jackiewicz Z. , Jorcyk C. L. , Kolev M. , Zubik-Kowal B.
Published: February 2009

This work demonstrates that prostate tumour progression in vivo can be analysed by using solutions of a mathematical model supplemented by initial conditions chosen according to growth rates of cell lines in vitro. The mathematical model is investigated and solved numerically. Its numerical solutions are compared with experimental data from animal models. The numerical results confirm the experimental results with the growth rates in vivo.
A Modified Stochastic Gompertz Model for Tumour Cell Growth
Authors: Lo C. F.
Published: February 2009

Based upon the deterministic Gompertz law of cell growth, we have proposed a stochastic model of tumour cell growth, in which the size of the tumour cells is bounded. The model takes account of both cell fission (which is an ‘action at a distance’ effect) and mortality too. Accordingly, the density function of the size of the tumour cells obeys a functional Fokker–Planck Equation (FPE) associated with the bounded stochastic process. We apply the Lie‐algebraic method to derive the exact analytical solution via an iterative approach. It is found that the density function exhibits an interesting kink‐like structure generated by cell fission as time evolves.
Phospholipase C–mediated hydrolysis of PIP2 releases ERM proteins from lymphocyte membrane
Authors: Hao Jian-Jiang , Liu Yin , Kruhlak Michael , Debell Karen E. , Rellahan Barbara L. , Shaw Stephen
Published: February 2009

Mechanisms controlling the disassembly of ezrin/radixin/moesin (ERM) proteins, which link the cytoskeleton to the plasma membrane, are incompletely understood. In lymphocytes, chemokine (e.g., SDF-1) stimulation inactivates ERM proteins, causing their release from the plasma membrane and dephosphorylation. SDF-1–mediated inactivation of ERM proteins is blocked by phospholipase C (PLC) inhibitors. Conversely, reduction of phosphatidylinositol 4,5-bisphosphate (PIP2) levels by activation of PLC, expression of active PLC mutants, or acute targeting of phosphoinositide 5-phosphatase to the plasma membrane promotes release and dephosphorylation of moesin and ezrin. Although expression of phosphomimetic moesin (T558D) or ezrin (T567D) mutants enhances membrane association, activation of PLC still relocalizes them to the cytosol. Similarly, in vitro binding of ERM proteins to the cytoplasmic tail of CD44 is also dependent on PIP2. These results demonstrate a new role of PLCs in rapid cytoskeletal remodeling and an additional key role of PIP2 in ERM protein biology, namely hydrolysis-mediated ERM inactivation.
Intrakinetochore stretch is associated with changes in kinetochore phosphorylation and spindle assembly checkpoint activity
Authors: Maresca Thomas J. , Salmon Edward D.
Published: February 2009

Cells have evolved a signaling pathway called the spindle assembly checkpoint (SAC) to increase the fidelity of chromosome segregation by generating a “wait anaphase” signal until all chromosomes are properly aligned within the mitotic spindle. It has been proposed that tension generated by the stretch of the centromeric chromatin of bioriented chromosomes stabilizes kinetochore microtubule attachments and turns off SAC activity. Although biorientation clearly causes stretching of the centromeric chromatin, it is unclear whether the kinetochore is also stretched. To test whether intrakinetochore stretch occurs and is involved in SAC regulation, we developed a Drosophila melanogaster S2 cell line expressing centromere identifier–mCherry and Ndc80–green fluorescent protein to mark the inner and outer kinetochore domains, respectively. We observed stretching within kinetochores of bioriented chromosomes by monitoring both inter- and intrakinetochore distances in live cell assays. This intrakinetochore stretch is largely independent of a 30-fold variation in centromere stretch. Furthermore, loss of intrakinetochore stretch is associated with enhancement of 3F3/2 phosphorylation and SAC activation.
Releasing the spindle assembly checkpoint without tension
Authors: McEwen Bruce F. , Dong Yimin
Published: February 2009

Eukaryotic cells have evolved a spindle assembly checkpoint (SAC) that facilitates accurate genomic segregation during mitosis by delaying anaphase onset in response to errors in kinetochore microtubule attachment. In contrast to the well-studied molecular mechanism by which the SAC blocks anaphase onset, the events triggering SAC release are poorly understood. Papers in this issue by Uchida et al. (Uchida, K.S.K., K. Takagaki, K. Kumada, Y. Hirayama, T. Noda, and T. Hirota. 2009. J. Cell Biol. 184:383–390) and Maresca and Salmon (Maresca, T.J., and E.D. Salmon. 2009. J. Cell Biol. 184:373–381) make an important advance by demonstrating that SAC release depends on molecular rearrangements within the kinetochore rather than tension-produced stretch between sister kinetochores.
Soluble Plant Cell Signals Induce the Expression of the Type III Secretion System of Pseudomonas syringae and Upregulate the Production of Pilus Protein HrpA
Authors: Haapalainen Minna , van Gestel Kristin , Pirhonen Minna , Taira Suvi
Published: February 2009

Type III protein secretion is essential for the pathogenicity of Pseudomonas syringae on its host plants. Expression of HrpA, a major component of the type III secretion system (T3SS)-associated pilus, was studied both in plant leaves and in vitro using reporter genes. We found that induction of the hrpA promoter was stronger in plants than in vitro, and that the induction was enhanced by both host and nonhost plants of P. syringae pv. tomato. In vitro, the expression was enhanced by cell-free exudates from plant cell suspension cultures, added into the minimal medium. Further analysis of the plant-cell-derived, hrpA-inducing factors showed that they were small and water-soluble compounds, which could signal P. syringae the proximity of living plant cells. We also studied the production and secretion of native HrpA protein in vitro, and detected a plant-signal-dependent increase in HrpA secretion. In contrast to HrpA, the intracellular accumulation or secretion of the other T3SS-dependent proteins were not significantly increased, despite the presence of plant cell-derived, promoter-inducing factors. Thus, the accumulation of HrpA pilin seems to be subjected to a distinct post-transcriptional regulation.
Identification of a New Biocontrol Gene in Trichoderma atroviride: The Role of an ABC Transporter Membrane Pump in the Interaction with Different Plant-Pathogenic Fungi
Authors: Ruocco Michelina , Lanzuise Stefania , Vinale Francesco , Marra Roberta , Turrà David , Woo Sheridan Lois , Lorito Matteo
Published: February 2009

Successful biocontrol interactions often require that the beneficial microbes involved are resistant or tolerant to a variety of toxicants, including antibiotics produced by themselves or phytopathogens, plant antimicrobial compounds, and synthetic chemicals or contaminants. The ability of Trichoderma spp., the most widely applied biocontrol fungi, to withstand different chemical stresses, including those associated with mycoparasitism, is well known. In this work, we identified an ATP-binding cassette transporter cell membrane pump as an important component of the above indicated resistance mechanisms that appears to be supported by an extensive and powerful cell detoxification system. The encoding gene, named Taabc2, was cloned from a strain of Trichoderma atroviride and characterized. Its expression was found to be upregulated in the presence of pathogen-secreted metabolites, specific mycotoxins and some fungicides, and in conditions that stimulate the production in Trichoderma spp. of antagonism-related factors (toxins and enzymes). The key role of this gene in antagonism and biocontrol was demonstrated by the characterization of the obtained deletion mutants. They suffered an increased susceptibility to inhibitory compounds either secreted by pathogenic fungi or possibly produced by the biocontrol microbe itself and lost, partially or entirely, the ability to protect tomato plants from Pythium ultimum and Rhizoctonia solani attack.
Symbiosis-Related Plant Genes Modulate Molecular Responses in an Arbuscular Mycorrhizal Fungus During Early Root Interactions
Authors: Seddas Pascale M. A. , Arias Cecilia M. , Arnould Christine , van Tuinen Diederik , Godfroy Olivier , Benhassou Hassan Aït , Gouzy Jérome , Morandi Dominique , Dessaint Fabrice , Gianinazzi-Pearson Vivienne
Published: February 2009

To gain further insight into the role of the plant genome in arbuscular mycorrhiza (AM) establishment, we investigated whether symbiosis-related plant genes affect fungal gene expression in germinating spores and at the appressoria stage of root interactions. Glomus intraradices genes were identified in expressed sequence tag libraries of mycorrhizal Medicago truncatula roots by in silico expression analyses. Transcripts of a subset of genes, with predicted functions in transcription, protein synthesis, primary or secondary metabolism, or of unknown function, were monitored in spores and germinating spores and during interactions with roots of wild-type or mycorrhiza-defective (Myc–) mutants of M. truncatula. Not all the fungal genes were active in quiescent spores but all were expressed when G. intraradices spores germinated in wild-type M. truncatula root exudates or when appressoria or arbuscules were formed in association with wild-type M. truncatula roots. Most of the fungal genes were upregulated or induced at the stage of appressorium development. Inactivation of the M. truncatula genes DMI1, DMI2/MtSYM2, or DMI3/MtSYM13 was associated with altered fungal gene expression (nonactivation or inhibition), modified appressorium structure, and plant cell wall responses, providing first evidence that cell processes modified by symbiosis-related plant genes impact on root interactions by directly modulating AM fungal activity.
Differential Responses of Resistant Soybean Entries to Isolates of Phakopsora pachyrhizi
Authors: Pham T. A. , Miles M. R. , Frederick R. D. , Hill C. B. , Hartman G. L.
Published: February 2009

Soybean rust, caused by the fungus Phakopsora pachyrhizi, was detected in the continental United States in 2004. Several new sources of resistance to P. pachyrhizi have been identified in soybean (Glycine max); however, there is limited information about their resistance when challenged with additional U.S. and international isolates. Resistance of 20 soybean (G. max) entries was compared after inoculation with 10 P. pachyrhizi isolates, representing different geographic and temporal origins. Soybean entries included 2 universal susceptible cultivars, 4 sources of soybean rust resistance genes (Rpp1–4), and 4 and 10 resistant entries selected from field trials in Paraguay and Vietnam, respectively. Of the known Rpp1–4 sources of resistance, plant introduction (PI) 459025B (Rpp4) produced reddish-brown (RB) lesions in response to all of the P. pachyrhizi isolates, while PI 230970 (Rpp2) produced RB lesions to all isolates except one from Taiwan, in response to which it produced a susceptible tan (TAN) lesion. PI 200492 (Rpp1) and PI 462312 (Rpp3) produced TAN lesions in response to most P. pachyrhizi isolates. The resistant entries selected from Paraguay and Vietnam varied considerably in their responses to the 10 P. pachyrhizi isolates, with M 103 the most susceptible and GC 84058-18-4 the most resistant. The reaction patterns on these resistant entries to the P. pachyrhizi isolates were different compared with the four soybean accessions with the Rpp genes, indicating that they contain novel sources of rust resistance. Among the P. pachyrhizi isolates, TW 72-1 from Taiwan and IN 73-1 from India produced the most susceptible and resistant reactions, respectively, on the soybean entries.
Effect of Fungicide and Timing of Application on Soybean Rust Severity and Yield
Authors: Mueller T. A. , Miles M. R. , Morel W. , Marois J. J. , Wright D. L. , Kemerait R. C. , Levy C. , Hartman G. L.
Published: February 2009

Soybean rust, caused by Phakopsora pachyrhizi, is a devastating foliar disease of soybean that may cause significant yield losses if not managed by well-timed fungicide applications. To determine the effect of fungicide timing on soybean rust severity and soybean yield, field trials were completed in Paraguay (four locations), the United States (two locations), and Zimbabwe (one location) from 2005 to 2006. Treatments at each location included applications of tebuconazole, pyraclostrobin, or a combination of azoxystrobin + propiconazole, and in some locations pyraclostrobin + tebuconazole at the following soybean growth stages (GS): (i) GS R1 (beginning flowering), (ii) GS R3 (beginning pod), (iii) GS R5 (beginning seed), (iv) GS R1 + R3, (v) GS R3 + R5, and (vi) GS R1 + R3 + R5. Soybean yields from plots treated with fungicides were 16 to 114% greater than yields from no fungicide control plots in four locations in Paraguay, 12 to 55% greater in two locations in the United States, and 31% greater in Zimbabwe. In all locations, rust severity measured over time as area under the disease progress curve (AUDPC) was negatively correlated (r = –0.3, P < 0.0001) to yield. The effectiveness of any given treatment (timing of application and product applied) was often dependent on when rust was first detected and the intensity of its development. For example, when soybean rust was first observed before GS R3 (two locations in Paraguay), the plants in plots treated with a fungicide at GS R1 had the lowest AUPDC values and highest yields. When soybean rust was first observed after GS R3, plants treated with a fungicide at GS R3 and/or GS R5 had the lowest AUDPC values and highest yields with a few exceptions.
Association of Solar Irradiance and Days of Precipitation with Incidence of Potato Late Blight in the Semiarid Environment of the Columbia Basin
Authors: Johnson Dennis A. , Cummings Thomas F. , Ghanem Rita Abi , Alldredge J. Richard
Published: February 2009

The effects of cumulative solar irradiance and rainfall on incidence of potato late blight (caused by Phytophthora infestans) in the Columbia Basin of south-central Washington and north-central Oregon were investigated using meteorological data collected near Othello, WA from 1990 through 2007 and Prosser, WA from 1990 through 2006. An association between solar irradiance and seasonal differences in late blight epidemics has not been quantitatively determined. Incidence of late blight in the Columbia Basin significantly increased as cumulative solar irradiance decreased during 1 April to 31 July and 1 June to 31 July at both Othello and Prosser. Incidence of late blight also increased as number of rainy days increased during 1 April to 31 July at Othello and Prosser and from 1 June to 31 July at Prosser. Coefficients of determination for significant models on late bight incidence ranged from 0.28 to 0.43 for cumulative solar irradiance and 0.27 to 0.38 for number of rainy days. Late blight incidence significantly increased as day of the year for first occurrence of late blight decreased in the Columbia Basin. A multiple regression model that included cumulative solar irradiance from 1 June to 31 July at Prosser and day of year for first occurrence of late blight as independent variables accounted for 58% of the variation for late blight incidence (adjusted R2 = 0.58), and a model that included number of cloudy days without rain combined with number of rainy days accounted for 62% of the variation for late blight incidence. This is the first report demonstrating a quantitative association of solar irradiance and incidence of late blight in commercial potato fields.
Effect of Temperature on Sporulation and Infectivity of Podosphaera macularis on Humulus lupulus
Authors: Peetz Amy B. , Mahaffee Walter F. , Gent David H.
Published: February 2009

Hop powdery mildew, caused by Podosphaera macularis, can result in complete crop loss and requires numerous fungicide applications for effective management. To assess the impact of temperature on the production of infective conidia, 10-day-old sporulating colonies were exposed to 18, 30, 33, 36, 39, and 42°C for 6 h, and then incubated at 18°C for 18 h. Conidia were harvested, inoculated onto hop plants, incubated at 18°C for 10 days, and then lesions/cm2 of leaf area was determined. Disease was significantly reduced at temperatures ≥30°C with a nonlinear response in the production of infective conidia (P < 0.0001). Temperature effects on sporulation of P. macularis were examined using a custom impaction conidia sampler in growth chambers programmed at constant temperatures of 5, 10, 15, 20, 25, 30, and 35°C, or 18°C before and after ramping to 18, 22, 26, 30, 34, and 38°C for 6 h. The effect of constant temperature on sporulation was best described by a nonlinear thermodynamic model (P = 0.0001) with maximal production near 25°C. Exposure to fluctuating temperatures produced a curvilinear response in sporulation (P = 0.0122) with maximum production near 25°C. These data indicate that inoculum availability is reduced when ambient temperature exceeds 30°C and that modeling inoculum availability could help further refine current disease forecasting models.
Temporal and Spatial Development of Sorghum Anthracnose in Arkansas
Authors: Li Yonghao , TeBeest David O.
Published: February 2009

Development of sorghum anthracnose in time and space on susceptible (‘BTx623’ and ‘Pioneer 8313’) and resistant (‘Cargill 888Y’) sorghum (Sorghum bicolor) cultivars was investigated in field plots inoculated with a mixture of three strains (T430-SW, Ar54-SW, and ArSS-1SW) of Colletotrichum sublineolum in 2001 and 2002. After slow development during early growth stages, sorghum anthracnose developed rapidly after flowering. The logistic model provided a good statistical fit for disease progress curves for sorghum anthracnose in Arkansas. Compared to susceptible cultivars, the resistant cultivar had significantly lower values for the standard area under the disease progress curve, a lower upper asymptote, and delayed epidemic onset. However, there were no significant differences in infection rate and the time of the inflection points, the times at which the disease proportion equaled values of one-half of upper asymptotes, among the three cultivars. The negative exponential model more closely described disease gradients of sorghum anthracnose than the inverse power law model. There were significant differences in intercepts but not in slopes and half-distance between the resistant and susceptible cultivars. The slopes of disease gradients were significantly lower at 78 days after inoculation (DAI) than at 57 DAI on the three cultivars. The results could provide epidemiological components of sorghum anthracnose to help evaluate sorghum cultivars and breeding lines under field conditions.
First Report of Columbia Root-Knot Nematode (Meloidogyne chitwoodi) in Potato in Turkey
Authors: Ozarslandan A. , Devran Z. , Mutlu N. , Elekcioglu I. H.
Published: February 2009

Columbia root-knot nematode, Meloidogyne chitwoodi Golden et al., was identified from potatoes, Solanum tuberosum L., collected from Nigde Province, Turkey in September 2006. Seed potatoes are the most likely source for this introduction. The nematode is currently found to be infecting potatoes grown in the Netherlands, Portugal, Belgium, Germany, the United States, Mexico, South Africa, and Argentina. M. chitwoodi acquired a quarantine status in Europe (1) because of its potential to become established worldwide and its high damage probability. Some countries prohibit import of both seed and table stock potatoes originating in states known to harbor M. chitwoodi. Lesions on the potatoes had discrete brown coloration with white central spots in the outer 1 cm of the tuber flesh. Female nematode densities averaged 3 to 5 per cm2 of a potato section beneath the lesions. Nematodes were morphologically identified as M. chitwoodi based on the perineal pattern of mature females and the tail shape of juveniles. Using PCR-restriction fragment length polymorphism of the 18S region (3) and the mtDNA COII-16S rRNA region (2) and intergenic spacer region between the 5S and 18S genes (4), individual juveniles were identified as M. chitwoodi based on their restriction fragment patterns. To our knowledge, this is the first report of Columbia root-knot nematode infecting potatoes in Turkey. The distribution of this nematode in potato fields throughout Turkey should be determined.

References: (1) L. J. M. F. Den Nijs et al. Nematology 6:303, 2004. (2) T. O. Powers and T. S. Harris. J. Nematol. 25:1, 1993. (3) T. O. Powers et al. J. Nematol. 37:226, 2005. (4) J. Wishart et al. Phytopathology 92:884, 2002.
First Report of Downy Mildew Caused by a Peronospora Species on Sweet Basil (Ocimum basilicum) in Massachusetts
Authors: Wick R. L. , Brazee N. J.
Published: February 2009

In September of 2008, downy mildew was discovered to be causing a serious foliar blight of sweet basil at several farms and greenhouses in Massachusetts. Infected leaves had chlorotic vein-bounded patches and diffuse chlorosis, and a characteristic gray, fuzzy growth was on the abaxial surface. Microscopic observations revealed branched sporangiophores that measured 187.5 to 325 μm (average 285 μm) long. Sporangia measured 22.5 to 30 × 20 to 22.5 μm (average 26.7 × 20.9 μm). No oospores were found. Sporangium measurements are comparable to unnamed Peronospora species reported previously on basil from Italy, Switzerland, and South Africa (1,2). Sequence analyses were conducted on five isolates of ‘Nufar’ basil by extracting DNA from a sporangial suspension washed from leaves and infected leaf tissues using the Qiagen DNeasy plant tissue kit (Qiagen, Valencia, CA). PCR amplification of the ITS1, 5.8S, and ITS2 region was performed using primers ITS6 and ITS4 (3). The sequences of the five isolates were identical. BLAST analyses of the sequences revealed a 99% similarity to the unnamed Peronospora species on sweet basil in Europe and South Africa (1,2). To our knowledge, this is the first report of a Peronospora species on sweet basil in Massachusetts.

References: (1) L. Belbahri et al. Mycol. Res. 109:1276, 2005. (2) A. McLeod et al. Plant Dis. 90:1115, 2006. (3) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.
A Phytoplasma Related to ‘Candidatus Phytoplasma asteris’ Detected in Citrus Showing Huanglongbing (Yellow Shoot Disease) Symptoms in Guangdong, P. R. China
Authors: Chen J. , Pu X. , Deng X. , Liu S. , Li H. , Civerolo E.
Published: February 2009

Citrus huanglongbing (HLB) or yellow shoot disease (i.e., greening disease) is highly destructive to citrus production worldwide. Understanding the etiology of HLB is critical for managing the disease. HLB is currently associated with infection by ‘Candidatus Liberibacter spp.’ around the world, including China. However, Koch's postulates have not been fulfilled. In addition, other plant pathogens also may be involved in HLB. In a survey performed in Guangdong Province, P. R. China in 2006 and 2007, 141 citrus samples showing typical symptoms of HLB from 11 different cities were collected. Polymerase chain reaction (PCR) using phytoplasma-specific primer sets fU5/rU3 nested with primer set P1/P7 identified 110 (78.0%) positive samples. A 1,785-bp amplicon was obtained with primer set P1/P7. Analysis showed a 100% identity of this sequence in the region of 16S rDNA and 16S-23S rRNA intergenic transcribed spacer to three strains of ‘Candidatus Phytoplasma asteris’ (onion yellows [Japan], aster yellows ‘watercress’ [Hawaii], and valeriana yellows [Lithuania]). Of the 141 samples, 89 (63.1%) samples were positive for ‘Ca. Liberibacter asiaticus’. When mixed infection was considered, 69 (48.9%) samples were positive for both ‘Ca. P. asteris’ and ‘Ca. L. asiaticus’. Transmission electron microscopy (TEM) showed low titers of both walled and wall-less bodies in the phloem sieve tubes of HLB citrus. When transmission from symptomatic citrus to periwinkle (Catharanthus roseus) via dodder (Cuscuta campestris) was conducted, both phytoplasma and ‘Ca. L. asiaticus’ were detected from the affected periwinkle. In addition to yellowing/mottling, the infected periwinkle showed symptoms of virescence and phyllody which are commonly associated with phytoplasmal diseases. TEM analysis of affected periwinkle revealed pleomorphic and wall-less organisms, characteristic of phytoplasmas, filling some phloem sieve tubes. In contrast, walled bacteria were at low titer. This study showed that in addition to ‘Ca. L. asiaticus’, a phytoplasma related to ‘Ca. P. asteris’ could also be detected in citrus showing HLB symptoms in Guangdong.
Cross-Protection Against Bean yellow mosaic virus (BYMV) and Clover yellow vein virus by Attenuated BYMV Isolate M11
Authors: Nakazono-Nagaoka Eiko , Takahashi Tsubasa , Shimizu Takumi , Kosaka Yoshitaka , Natsuaki Tomohide , Omura Toshihiro , Sasaya Takahide
Published: February 2009

Attenuated isolate M11 of Bean yellow mosaic virus (BYMV), obtained after exposing BYMV-infected plants to low temperature, and its efficacy in cross-protecting against infection by BYMV isolates from gladiolus, broad bean (Vicia faba) and white clover (Trifolium repens) was assessed with western blotting and reverse transcription-polymerase chain reaction. The level of cross-protection varied depending on the challenge virus isolates. Cross-protection was complete against BYMV isolates from gladiolus, but incomplete against BYMV isolates from other hosts. M11 also partially cross-protected against an isolate of Clover yellow vein virus. A comparison of the nucleotide sequence of M11 and those of BYMV isolates from gladiolus and from other hosts showed higher homology among gladiolus isolates than the homology between gladiolus isolates and nongladiolus isolates. In the phylogenetic trees, constructed using the nucleotide sequences of an overall polyprotein of the genomes, five gladiolus isolates clustered together, completely separated from the three BYMV isolates from other hosts. A comparison of the amino acid sequences between M11 and its parental isolate IbG, and analysis of recombinant infectious clones between M11 and IbG revealed that an amino acid at position 314 was involved in the attenuation of BYMV.
Indole-3-Acetic Acid Improves Postharvest Biological Control of Blue Mold Rot of Apple by Cryptococcus laurentii
Authors: Yu Ting , Chen Jishuang , Lu Huangping , Zheng Xiaodong
Published: February 2009

Cryptococcus laurentii is a well-known postharvest biocontrol yeast; however, it cannot provide satisfactory levels of decay control when used alone. Here, we evaluated the effects of indole-3-acetic acid (IAA), a plant growth regulator, on the biocontrol efficacy of the yeast antagonist C. laurentii against blue mold rot caused by Penicillium expansum in apple fruit. Results showed that the addition of IAA at 20 μg/ml to suspensions of C. laurentii greatly enhanced inhibition of mold rot in apple wounds compared with that observed with C. laurentii alone. The addition of IAA at 20 μg/ml or lower did not influence the population growth of C. laurentii in wounds, but adverse effects were seen on C. laurentii when the concentration of IAA was increased to 200 μg/ml or above in vitro and in vivo. P. expansum infection in apple wounds was not inhibited when the pathogen was inoculated into the fruit wounds within 2 h after application of IAA; however, infection was reduced when inoculated more than 12 h after IAA application. Treatment of wounds with IAA at 20 μg/ml 24 h before pathogen inoculation resulted in significant inhibition of P. expansum spore germination and host infection. Application of IAA at 20 μg/ml also reduced P. expansum infection when it was applied 48 h before pathogen inoculation in the intact fruit. Thus, IAA could reinforce the biocontrol efficacy of C. laurentii in inhibiting blue mold of apple fruit by induction of the natural resistance of the fruit.
Efficient Transmission of ‘CandidatusPhytoplasma prunorum’ Is Delayed by Eight Months Due to a Long Latency in Its Host-Alternating Vector
Authors: Thébaud Gaël , Yvon Michel , Alary Rémi , Sauvion Nicolas , Labonne Gérard
Published: February 2009

Understanding at which spatiotemporal scale a disease causes significant secondary spread has both theoretical and practical implications. We investigated this issue in the case of European stone fruit yellows (ESFY), a quarantine vector-borne phytoplasma disease of Prunus trees. Our work was focused on the processes underlying disease spread: the interplay between the life cycles of the pathogen (‘Candidatus Phytoplasma prunorum’) and of the vector (Cacopsylla pruni). We demonstrated experimentally that C. pruni has only one generation per year and we showed that, at least in southeastern France, C. pruni migrates between conifers in mountainous regions (where it overwinters) and Prunus spp. at lower altitude (where it breeds). In acquisition–inoculation experiments performed with C. pruni over its period of presence on Prunus spp., both immature and mature C. pruni were hardly infectious (0.6%) despite effective phytoplasma acquisition and multiplication. We demonstrated that most immature vectors born on infected plants reach their maximum phytoplasma load (107genomes per insect) only after migrating to conifers and that, after a life-long retention of the phytoplasma, their transmission efficiency was very high (60%) at the end of winter (when they migrate back to their Prunus host). Thus, most transmissions occur only after an effective latency of 8 months, following vector migrations and overwintering on conifers in mountainous regions. From this transmission cycle, we can infer that local secondary spread of ESFY in apricot orchards is marginal, and recommend that disease management strategies take more into account the processes occurring at a regional scale, including the role of wild Prunus spp. in ESFY epidemics.
Detection of High Concentrations of Organic Acids in Fish Emulsion and Their Role in Pathogen or Disease Suppression
Authors: Abbasi Pervaiz A. , Lazarovits George , Jabaji-Hare Suha
Published: February 2009

Fish emulsion (FE) added to a sandy-loam soil at 1 and 2% rates reduced the viability of Verticillium dahliae microsclerotia by 39 and 74% in 1 day, 87 and 98% in 3 days, and 95 and 99% in 6 days, respectively. The immediate kill of microsclerotia indicated that FE contains toxic substances. We found in FE high concentrations (400 mmol/liter) of organic acids, including some known toxicants. Glycolic, acetic, formic, n-butyric, and propionic acids were the major organic acids detected in FE at the proportions of 52.5, 26.9, 7.9, 7.2, and 4.7%, respectively. In solution assays, the viability of V. dahliae microsclerotia treated for 24 h in 1, 2, 5, and 10% FE (pH 3.6 to 3.0) or a mixture of organic acids (pH 4.1 to 3.9) equivalent to the proportions in FE was reduced by 74, 94, 97, and 99% or 81, 91, 98, and 99%, respectively. The viability of microsclerotia was increased when the treatment solutions were buffered to pH 6.0. The organic acids mixtures and formic (0.025%) and acetic (0.1%) acids were toxic to Pythium ultimum. A mixture of organic acids (1, 2, and 4%) provided immediate protection of cucumber seedlings from damping-off in P. ultimum-infested muck and sandy-loam soils but not in peat-based mix. FE (1 and 2%) provided immediate protection of cucumber seedlings from damping-off in an infested muck soil, and disease protection was consistent when planting was delayed for 7, 14, and 28 days after adding FE. FE (1, 2, and 4%) did not provide immediate protection of cucumber seedlings from damping-off in a P. ultimum-infested peat-based mix; however, disease suppression was evident when planting was delayed for 7, 14, and 21 days after adding FE. Real-time polymerase chain reaction analyses of the peat-based mix indicated that the P. ultimum populations in the FE-amended mix declined over time. This study suggests that these organic acids in FE played a major role in pathogen or disease suppression, depending on the soil and substrate.