Low genetic variation detected in New Zealand populations of Phaeomoniella chlamydospora

Phaeomoniella chlamydospora is considered to be the causal agent of Petri disease. This disease causes decline of grapevines in most grape growing regions of the world. Genetic variation within 39 New Zealand isolates of Phaeomoniella chlamydospora was compared to six isolates from Italy using randomly amplified polymorphic DNA (RAPD), randomly amplified microsatellites (RAM), amplified fragment length polymorphism (AFLP), and universally primed polymerase chain reaction (UP-PCR). Using each method, genetic variation within New Zealand and Italian isolates of P. chlamydospora was shown to be low, with a maximum of seven genetic groups identified by each primer. The greatest amount of genetic variation was shown using AFLP analysis, with 21 different groups identified. RAPD, AFLP and UP-PCR primers detected inter-vineyard, intra-vineyard and intra-vine variation of New Zealand isolates. A subset of five New Zealand and one Italian isolate was further investigated using mycelial compatibility groups (MCGs). One MCG was identified, supporting low genetic variation within P. chlamydospora isolates. Low genetic variation within the New Zealand and the Italian populations suggests that asexual reproduction predominates, and the presence of intra-vineyard and intra-vine variation in New Zealand indicates that multiple introductions have occurred

Spin-1/2 J1-J2 model on the body-centered cubic lattice

Using exact diagonalization (ED) and linear spin wave theory (LSWT) we study the influence of frustration and quantum fluctuations on the magnetic ordering in the ground state of the spin-1/2 J1-J2 Heisenberg antiferromagnet (J1-J2 model) on the body-centered cubic (bcc) lattice. Contrary to the J1-J2 model on the square lattice, we find for the bcc lattice that frustration and quantum fluctuations do not lead to a quantum disordered phase for strong frustration. The results of both approaches (ED, LSWT) suggest a first order transition at J2/J1 $\approx$ 0.7 from the two-sublattice Neel phase at low J2 to a collinear phase at large J2.Comment: 6.1 pages 7 figure

Flow interactions with an aquatic macrophyte: a field study using stereoscopic particle image velocimetry

This paper reports the morphology of a natural patch of Ranunculus penicillatus and presents high-resolution measurements of flow velocities in its wake using a stereoscopic PIV field measurement system. The patch was 3.80 m long, 1.24 m wide and caused substantial changes to downstream mean velocities and turbulence. Vertical profiles of streamwise mean velocity were not logarithmic and flow was redirected under the positively buoyant canopy, enhancing vertical turbulent mixing in the wake and generating a large region where the velocity covariance u'w' was positive. Turbulent kinetic energy was enhanced downstream from the patch lateral shear layer, but not at the centre of the wake. Spectra downstream from the patch showed that turbulence was neither dominated by fine-scale nor large-scale structures, likely due to the low energy of the flow conditions and lack of a developed vortex street within the measurement domain. Sedimentation was observed at the upstream end of the patch, but not underneath the floating canopy. The methods and results of this work will be useful for planning other in situ studies. Also, the reported data on macrophyte geometry and biometrics will assist with the design of more realistic replicas for use in laboratory studies

The effect of common genetic variation in 11β-hydroxysteroid dehydrogenase type 1 on hypothalamic-pituitary-adrenal axis activity and incident depression

Background: Accumulating evidence suggests that hyperactivity of the hypothalamic-pituitary-adrenal axis (HPA axis) is involved in depression. 11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) converts inert cortisone to active cortisol and is implicated in HPA axis regulation in animal studies. The aim of our study was to identify polymorphisms in 11β-HSD1 gene (HSD11B1) with consistent associations with increased HPA axis activity and relate those polymorphisms to depression. Methods: Twelve single-nucleotide polymorphisms (SNPs), including 11 tagging SNPs, were selected using the HapMap database and genotyped in 4228 participants of the population-based Rotterdam Study. The outcome measures were salivary cortisol levels after awakening, 30 min later, at 1700 h, at bedtime, and plasma levels of androstenedione (in women only). SNPs that were significantly associated with cortisol as well as androstenedione levels were also related to incident depression. Results: rs11119328 was associated with higher cortisol saliva samples collected at bedtime as well as higher androstenedione levels (P value after correction for multiple testing: 0.01 and 0.04, respectively). Carriers of this polymorphism had an increased risk of an incident depression (hazard ratio 1.28, 95% confidence interval 1.03-1.59). Two other SNPs, which were in high linkage disequilibrium with rs11119328, were related to higher cortisol levels but not with androstenedione levels. Conclusions: We identified one SNP, which was associated with increased salivary cortisol levels at nadir as well as higher androstenedione levels. Moreover, this SNP was also associated with a higher risk of an incident depression. This suggests that 11β-HSD1 is implicated in human HPA axis regulation and susceptibility to depression. Copyrigh

Experimental infection of sheep with ovine and bovine Dichelobacter nodosus isolates

AbstractThe aim of this study was, under experimental conditions, to investigate infection of Norwegian White sheep with ovine and bovine isolates of Dichelobacter nodosus of varying virulence. In addition, the efficacy of gamithromycin as a treatment for the experimentally induced infections was examined. The study was performed as a single foot inoculation using a boot. Four groups, each with six lambs, were inoculated with four different challenge strains (Group 1: benign bovine strain; Group 2: virulent bovine strain; Group 3: benign ovine strain; Group 4: virulent ovine strain). The main criterion to determine that infection was transferred was that D. nodosus isolate was obtained by culture. After the trial all lambs were treated with gamithromycin. Clinical symptoms of footrot developed in all groups, and when removing the boots two weeks after challenge, D. nodosus was isolated from 5 of 24 experimental lambs. All lambs tested negative for D. nodosus by PCR within six weeks after treatment with gamithromycin. This study strongly indicates that D. nodosus isolates from both sheep and cattle can be transferred to sheep under experimental conditions. The study also indicates that gamithromycin may be effective against D. nodosus

Large-scale pharmacogenomic study of sulfonylureas and the QT, JT and QRS intervals: CHARGE Pharmacogenomics Working Group

Sulfonylureas, a commonly used class of medication used to treat type 2 diabetes, have been associated with an increased risk of cardiovascular disease. Their effects on QT interval duration and related electrocardiographic phenotypes are potential mechanisms for this adverse effect. In 11 ethnically diverse cohorts that included 71 857 European, African-American and Hispanic/Latino ancestry individuals with repeated measures of medication use and electrocardiogram (ECG) measurements, we conducted a pharmacogenomic genome-wide association study of sulfonylurea use and three ECG phenotypes: QT, JT and QRS intervals. In ancestry-specific meta-analyses, eight novel pharmacogenomic loci met the threshold for genome-wide significance (P<5 × 10−8), and a pharmacokinetic variant in CYP2C9 (rs1057910) that has been associated with sulfonylurea-related treatment effects and other adverse drug reactions in previous studies was replicated. Additional research is needed to replicate the novel findings and to understand their biological basis

Transport properties of strongly correlated metals:a dynamical mean-field approach

The temperature dependence of the transport properties of the metallic phase of a frustrated Hubbard model on the hypercubic lattice at half-filling are calculated. Dynamical mean-field theory, which maps the Hubbard model onto a single impurity Anderson model that is solved self-consistently, and becomes exact in the limit of large dimensionality, is used. As the temperature increases there is a smooth crossover from coherent Fermi liquid excitations at low temperatures to incoherent excitations at high temperatures. This crossover leads to a non-monotonic temperature dependence for the resistance, thermopower, and Hall coefficient, unlike in conventional metals. The resistance smoothly increases from a quadratic temperature dependence at low temperatures to large values which can exceed the Mott-Ioffe-Regel value, hbar a/e^2 (where "a" is a lattice constant) associated with mean-free paths less than a lattice constant. Further signatures of the thermal destruction of quasiparticle excitations are a peak in the thermopower and the absence of a Drude peak in the optical conductivity. The results presented here are relevant to a wide range of strongly correlated metals, including transition metal oxides, strontium ruthenates, and organic metals.Comment: 19 pages, 9 eps figure

Fermi Surface Variation of Ce 4f-electrons in Hybridization Controlled Heavy-Fermion Systems

Ce 3d-4f resonant angle-resolved photoemission measurements on CeCoGe$_{1.2}$Si$_{0.8}$ and CeCoSi$_{2}$ have been performed to understand the Fermi surface topology as a function of hybridization strength between Ce 4$f$- and conduction electrons in heavy-fermion systems. We directly observe that the hole-like Ce 4$f$-Fermi surfaces of CeCoSi$_{2}$ is smaller than that of CeCoGe$_{1.2}$Si$_{0.8}$, indicating the evolution of the Ce 4$f$-Fermi surface with the increase of the hybridization strength. In comparision with LDA calculation, the Fermi surface variation cannot be understood even though the overall electronic structure are roughly explained, indicating the importance of strong correlation effects. We also discuss the relation between the Ce 4$f$-Fermi surface variation and the Kondo peaks.Comment: 7 pages, 3 figures, submitte

Incorporating scale invariance into the cellular associative neural network

This paper describes an improvement to the Cellular Associative Neural Network, an architecture based on the distributed model of a cellular automaton, allowing it to perform scale invariant pattern matching. The use of tensor products and superposition of patterns allows the system to recall patterns at multiple resolutions simultaneously. Our experimental results show that the architecture is capable of scale invariant pattern matching, but that further investigation is needed to reduce the distortion introduced by image scaling

The induction of behavioural sensitization is associated with cocaine-induced structural plasticity in the core (but not shell) of the nucleus accumbens

Repeated exposure to cocaine increases the density of dendritic spines on medium spiny neurons in the nucleus accumbens (Acb) and pyramidal cells in the medial prefrontal cortex (mPFC). To determine if this is associated with the development of psychomotor sensitization, rats were given daily i.p. injections of 15 mg/kg of cocaine (or saline) for 8 days, either in their home cage (which failed to induce significant psychomotor sensitization) or in a distinct and relatively novel test cage (which induced robust psychomotor sensitization). Their brains were obtained 2 weeks after the last injection and processed for Golgi–Cox staining. In the Acb core (AcbC) cocaine treatment increased spine density only in the group that developed psychomotor sensitization (i.e. in the Novel but not Home group), and there was a significant positive correlation between the degree of psychomotor sensitization and spine density. In the Acb shell (AcbS) cocaine increased spine density to the same extent in both groups; i.e. independent of psychomotor sensitization. In the mPFC cocaine increased spine density in both groups, but to a significantly greater extent in the Novel group. Furthermore, when rats were treated at Home with a higher dose of cocaine (30 mg/kg), cocaine now induced psychomotor sensitization in this context, and also increased spine density in the AcbC. Thus, the context in which cocaine is experienced influences its ability to reorganize patterns of synaptic connectivity in the Acb and mPFC, and the induction of psychomotor sensitization is associated with structural plasticity in the AcbC and mPFC, but not the AcbS.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73532/1/j.1460-9568.2004.03612.x.pd