Optimising initial population density, growth time and nitrogen nutrition for assessing resistance of wheat cultivars to root-lesion nematode (Pratylenchus thornei)

Pratylenchus thornei is a major pathogen of wheat in Australia. Two glasshouse experiments with four wheat cultivars that had different final populations (Pf) of P. thornei in the field were used to optimise conditions for assessing resistance. With different initial populations (Pi) ranging up to 5250 P. thornei/kg soil, Pf of P. thornei increased to 16 weeks after sowing, and then decreased at 20 weeks in some cultivar x Pi combinations. The population dynamics of P. thornei up to 16 weeks were best described by a modified exponential equation P f (t) = aP i e kt where P f (t) is the final population density at time t, P i is the initial population density, a is the proportion of P i that initiates population development, and k is the intrinsic rate of increase of the population. The cultivar GS50a had very low k values at Pi of 5250 and 1050 indicating its resistance, Suneca and Potam had high k values indicating susceptibility, whereas intolerant Gatcher had a low value at the higher Pi and a high value at the lower Pi. Nitrate fertiliser increased plant growth and Pf values of susceptible cultivars, but in unplanted soil it decreased Pf. Nematicide (aldicarb 5 mg/kg soil) killed P. thornei more effectively in planted than in unplanted soil and increased plant growth particularly in the presence of N fertiliser. In both experiments, the wheat cultivars Suneca and Potam were more susceptible than the cultivar GS50a reflecting field results. The method chosen to discriminate wheat cultivars was to assess Pf after growth for 16 weeks in soil with Pi ~1050–5250 P. thornei/kg soil and fertilised with 200 mg NO3–N/kg soil.

A boat hitchhiker’s guide to survival: Cabomba caroliniana desiccation resistance and survival ability

Cabomba caroliniana is a submersed macrophyte that has become a serious invader. Cabomba predominantly spreads by stem fragments, in particular through unintentional transport on boat trailers (‘hitch hiking’). Desiccation resistance affects the potential dispersal radius. Therefore, knowledge of maximum survival times allows predicting future dispersal. Experiments were conducted to assess desiccation resistance and survival ability of cabomba fragments under various environmental scenarios. Cabomba fragments were highly tolerant of desiccation. However, even relatively low wind speeds resulted in rapid mass loss, indicating a low survival rate of fragments exposed to air currents, such as fragments transported on a boat trailer. The experiments indicated that cabomba could survive at least 3 h of overland transport if exposed to wind. However, even small clumps of cabomba could potentially survive up to 42 h. Thus, targeting the transport of clumps of macrophytes should receive high priority in management. The high resilience of cabomba to desiccation demonstrates the risk of continuing spread. Because of the high probability of fragment viability on arrival, preventing fragment uptake on boat trailers is paramount to reduce the risk of further spread. These findings will assist improving models that predict the spread of aquatic invasive macrophytes.

Susceptibility to sulfuryl fluoride and lack of cross-resistance to phosphine in developmental stages of the red flour beetle, Tribolium castaneum (Coleoptera: Tenebrionidae)

BACKGROUND Our aim was to ascertain the potential of sulfuryl fluoride (SF) as an alternative fumigant to manage phosphine-resistant pests. We tested the susceptibility of all life stages of red flour beetle, Tribolium castaneum (Herbst), to SF and assessed the presence of cross-resistance to this fumigant in phosphine-resistant strains of this species. RESULTS Analysis of dose–response data indicated that the egg was the stage most tolerant to SF under a 48 h exposure period. At LC50, eggs were 29 times more tolerant than other immature stages and adults, and required a relatively high concentration of 48.2 mg L−1 for complete mortality. No significant differences in tolerance to SF were observed among the three larval instars, pupae and adults, and all of these stages were controlled at a low concentration of 1.32 mg L−1. Phosphine-resistant strains did not show cross-resistance to SF. CONCLUSION Our research concluded that the current maximum registered rate of SF, 1500 gh m−3, is adequate to control all the post-embryonic life stages of T. castaneum over a 48 h fumigation period, but it will fail to achieve complete mortality of eggs, indicating the risk of some survival of eggs under this short exposure period. As there is no cross-resistance to SF in phosphine-resistant insects, it will play a key role in managing phosphine resistance in stored-grain insect pests. © 2014 Commonwealth of Australia. Pest Management Science © 2014 Society of Chemical Industry

Resistance Minimum in Dilute Magnetic Alloys in the Absence of Impurity Moments

A possible mechanism for the resistance minimum in dilute alloys in which the localized impurity states are non-magnetic is suggested. The fact is considered that what is essential to the Kondo-like behaviour is the interaction of the conduction electron spin s with the internal dynamical degrees of freedom of the impurity centre. The necessary internal dynamical degrees of freedom are provided by the dynamical Jahn-Teller effect associated with the degenerate 3d-orbitals of the transition-metal impurities interacting with the surrounding (octahedral) complex of the nearest-neighbour atoms. The fictitious spin I characterizing certain low-lying vibronic states of the system is shown to couple with the conduction electron spin s via s-d mixing and spin-orbit coupling, giving rise to a singular temperature-dependent exchange-like interaction. The resistivity so calculated is in fair agreement with the experimental results of Cape and Hake for Ti containing 0.2 at% of Fe.

Highly heritable resistance to root-lesion nematode (Pratylenchus thornei) in Australian chickpea germplasm observed using an optimised glasshouse method and multi-environment trial analysis

Pratylenchus thornei is a root-lesion nematode (RLN) of economic significance in the grain growing regions of Australia. Chickpea (Cicer arietinum) is a significant legume crop grown throughout these regions, but previous testing found most cultivars were susceptible to P. thornei. Therefore, improved resistance to P. thornei is an important objective of the Australian chickpea breeding program. A glasshouse method was developed to assess resistance of chickpea lines to P. thornei, which requires relatively low labour and resource input, and hence is suited to routine adoption within a breeding program. Using this method, good differentiation of chickpea cultivars for P. thornei resistance was measured after 12 weeks. Nematode multiplication was higher for all genotypes than the unplanted control, but of the 47 cultivars and breeding lines tested, 17 exhibited partial resistance, allowing less than two fold multiplication. The relative differences in resistance identified using this method were highly heritable (0.69) and were validated against P. thornei data from seven field trials using a multi-environment trial analysis. Genetic correlations for cultivar resistance between the glasshouse and six of the field trials were high (>0.73). These results demonstrate that resistance to P. thornei in chickpea is highly heritable and can be effectively selected in a limited set of environments. The improved resistance found in a number of the newer chickpea cultivars tested shows that some advances have been made in the P. thornei resistance of Australian chickpea cultivars, and that further targeted breeding and selection should provide incremental improvements.

Impact of resistance exercise on ribosome biogenesis is acutely regulated by post-exercise recovery strategies

Muscle hypertrophy occurs following increased protein synthesis, which requires activation of the ribosomal complex. Additionally, increased translational capacity via elevated ribosomal RNA (rRNA) synthesis has also been implicated in resistance training-induced skeletal muscle hypertrophy. The time course of ribosome biogenesis following resistance exercise (RE) and the impact exerted by differing recovery strategies remains unknown. In the present study, the activation of transcriptional regulators, the expression levels of pre-rRNA, and mature rRNA components were measured through 48 h after a single-bout RE. In addition, the effects of either low-intensity cycling (active recovery, ACT) or a cold-water immersion (CWI) recovery strategy were compared. Nine male subjects performed two bouts of high-load RE randomized to be followed by 10 min of either ACT or CWI. Muscle biopsies were collected before RE and at 2, 24, and 48 h after RE. RE increased the phosphorylation of the p38-MNK1-eIF4E axis, an effect only evident with ACT recovery. Downstream, cyclin D1 protein, total eIF4E, upstream binding factor 1 (UBF1), and c-Myc proteins were all increased only after RE with ACT. This corresponded with elevated abundance of the pre-rRNAs (45S, ITS-28S, ITS-5.8S, and ETS-18S) from 24 h after RE with ACT. In conclusion, coordinated upstream signaling and activation of transcriptional factors stimulated pre-rRNA expression after RE. CWI, as a recovery strategy, markedly blunted these events, suggesting that suppressed ribosome biogenesis may be one factor contributing to the impaired hypertrophic response observed when CWI is used regularly after exercise.

Lowering grain boundary resistance of BaZr0.8Y0.2O3−δ with LiNO3 sintering-aid improves proton conductivity for fuel cell operation

A novel sintering additive based on LiNO3 was used to overcome the drawbacks of poor sinterability and low grain boundary conductivity in BaZr0.8Y0.2O3-δ (BZY20) protonic conductors. The Li-additive totally evaporated during the sintering process at 1600°C for 6 h, which led to highly dense BZY20 pellets (96.5% of the theoretical value). The proton conductivity values of BZY20 with Li sintering-aid were significantly larger than the values reported for BZY sintered with other metal oxides, due to the fast proton transport in the "clean" grain boundaries and grain interior. The total conductivity of BZY20-Li in wet Ar was 4.45 × 10-3 S cm-1 at 600°C. Based on the improved sinterability, anode-supported fuel cells with 25 μm-thick BZY20-Li electrolyte membranes were fabricated by a co-firing technique. The peak power density obtained at 700°C for a BZY-Ni/BZY20-Li/La0.6Sr0.4Co0.2Fe 0.8O3-δ (LSCF)-BZY cell was 53 mW cm-2, which is significantly larger than the values reported for fuel cells using electrolytes made of BZY sintered with the addition of ZnO and CuO, confirming the advantage of using Li as a sintering aid.

Vacuum ultraviolet/atomic oxygen erosion resistance of amorphous Si0.26C0.43N0.31 coating

An amorphous silicon carbonitride (Si1-x-yCxN y, x = 0:43, y = 0:31) coating was deposited on polyimide substrate using the magnetron-sputtering method. Exposure tests of the coated polyimide in atomic oxygen beam and vacuum ultraviolet radiation were performed in a ground-based simulator. Erosion kinetics measurements indicated that the erosion yield of the Si0.26C0.43N0.31 coating was about 1.5x and 1.8 × 10-26 cm3 /atom during exposure in single atomic oxygen beam, simultaneous atomic oxygen beam, and vacuum ultraviolet radiation, respectively. These values were 2 orders of magnitude lower than that of bare polyimide substrate. Scanning electron and atomic force microscopy, X-ray photoelectron spectrometer, and Fourier transformed infrared spectroscopy investigation indicated that during exposures, an oxide-rich layer composed of SiO2 and minor Si-C-O formed on the surface of the Si 0.26C0.43N0.31 coating, which was the main reason for the excellent resistance to the attacks of atomic oxygen. Moreover, vacuum ultraviolet radiation could promote the breakage of chemical bonds with low binding energy, such as C-N, C = N, and C-C, and enhance atomic oxygen erosion rate slightly.

Thermal properties and thermal shock resistance of γ-Y 2Si2O7

Thermal properties, namely, Debye temperature, thermal expansion coefficient, heat capacity, and thermal conductivity of γ-Y 2Si2O7, a high-temperature polymorph of yttrium disilicate, were investigated. The anisotropic thermal expansions of γ-Y2Si2O7 powders were examined using high-temperature X-ray diffractometer from 300 to 1373 K and the volumetric thermal expansion coefficient is (6.68±0.35) × 10-6 K-1. The linear thermal expansion coefficient of polycrystalline γ-Y2Si2O7 determined by push-rod dilatometer is (3.90±0.4) × 10-6 K-1, being very close to that of silicon nitride and silicon carbide. Besides, γ-Y2Si2O7 displays a low-thermal conductivity, with a κ value measured below 3.0 W·(m·K) -1 at the temperatures above 600 K. The calculated minimum thermal conductivity, κmin, was 1.35 W·(m·K) -1. The unique combination of low thermal expansion coefficient and low-thermal conductivity of γ-Y2Si2O7 renders it a very competitive candidate material for high temperature structural components and environmental/thermal-barrier coatings. The thermal shock resistance of γ-Y2Si2O7 was estimated by quenching dense materials in water from various temperatures and the critical temperature difference, ΔTc, was determined to be 300 K.

Mulibrey nanism : Clinical characteristics and pathophysiologic features of growth restriction, insulin resistance and tumour development

Background: Mulibrey nanism (MUL; Muscle-liver-brain-eye nanism; OMIM 253250) is an autosomal recessive growth disorder more prevalent in Finland than elsewhere in the world. Clinical characteristics include severe prenatal onset growth restriction, cardiopathy, multiple organ manifestations but no major neurological handicap. MUL is caused by mutations in the TRIM37 gene on chromosome 17q22-23, encoding a peroxisomal protein TRIM37 with ubiquitin E3-ligase activity. Nineteen different mutations have been detected, four of them present in the Finnish patients. Objective: This study aimed to characterize clinical and histopathological features of MUL in the national cohort of Finnish patients. Patients and methods: A total of 92 Finnish patients (age 0.7 to 77 years) participated in the clinical follow-up study. Patients hospital records and growth charts were reviewed. Physical, radiographic and laboratory examinations were performed according to a clinical protocol. Thirty patients (18 females) were treated with recombinant human GH for a median period of 5.7 years. Biopsies and autopsy samples were used for the histopathological and immunohistochemical analyses. Results: MUL patients were born small for gestational age (SGA) with immature craniofacial features after prenatal-onset growth restriction. They experienced a continuous deceleration in both height SDS and weight-for-height (WFH) postnatally. In infancy feeding difficulties and frequent pneumonias were common problems. At the time of diagnosis (median age 2.1 years) characteristic craniofacial, radiological and ocular features were the most constant findings. MUL patients showed a dramatic change in glucose metabolism with increasing age. While the children had low fasting glucose and insulin levels, 90% of the adults were insulin resistant, half had type 2 diabetes and an additional 42% showed impaired glucose tolerance (IGT). Seventy percent fulfilled the National Cholesterol Education Program (NCEP) Adult Treatment Panel III criteria for metabolic syndrome as adults. GH therapy improved pre-pubertal growth but had only minor impact on adult height (+5 cm). Interestingly, treated subjects were slimmer and had less frequent metabolic concerns as young adults. MUL patients displayed histologically a disturbed architecture with ectopic tissues and a high frequency of both benign and malignant tumours present in several internal organs. A total of 232 tumorous lesions were detected in our patient cohort. The majority of the tumours showed strong expression of endothelial cell marker CD34 as well as α-smooth muscle actin (α-SMA). Fifteen of the tumours were malignant and seven of them (five Wilms tumours) occurred in the kidney. Conclusions: MUL patients present a distinct postnatal growth pattern. Short-term response of GH treatment is substantial but the long-term impact remains modest. Although MUL patients form a distinct clinical and diagnostic entity, their clinical findings vary considerably from infancy to adulthood. While failure to thrive dominates early life, MUL adults develop metabolic syndrome and have a tendency for malignancies and vascular lesions in several organs. This speaks for a central role of TRIM37 in regulation of key cellular functions, such as proliferation, migration, angiogenesis and insulin signalling.

Helicobacter pylori: resistance and treatment results in Finland

Background: Helicobacter pylori infection is usually acquired in early childhood and is rarely resolved spontaneously. Eradication therapy is currently recommended virtually to all patients. While the first and second therapies are prescribed without knowing the antibiotic resistance of the bacteria, it is important to know the primary resistance in the population. Aim: This study evaluates the primary resistance of H. pylori among patients in primary health care throughout Finland, the efficacy of three eradication regimens, the symptomatic response to successful therapy, and the effect of smoking on gastric histology and humoral response in H. pylori-positive patients. Patients and methods: A total of 23 endoscopy referral centres located throughout Finland recruited 342 adult patients with positive rapid urease test results, who were referred to upper gastrointestinal endoscopy from primary health care. Gastric histology, H. pylori resistance and H. pylori serology were evaluated. The patients were randomized to receive a seven-day regimen, comprising 1) lansoprazole 30 mg b.d., amoxicillin 1 g b.d. and metronidazole 400 mg t.d. (LAM), 2) lansoprazole 30 mg b.d., amoxicillin 1 g b.d. and clarithromycin 500 mg b.d. (LAC) or 3) ranitidine bismuth citrate 400 mg b.d., metronidazole 400 mg t.d. and tetracycline 500 mg q.d. (RMT). The eradication results were assessed, using the 13C-urea breath test 4 weeks after therapy. The patients completed a symptom questionnaire before and a year after the therapy. Results: Primary resistance of H. pylori to metronidazole was 48% among women and 25% among men. In women, metronidazole resistance correlated with previous use of antibiotics for gynaecologic infections and alcohol consumption. Resistance rate to clarithromycin was only 2%. Intention-to-treat cure rates of LAM, LAC, and RMT were 78%, 91% and 81%. While in metronidazole-sensitive cases the cure rates with LAM, LAC and RMT were similar, in metronidazole resistance LAM and RMT were inferior to LAC (53%, 67% and 84%). Previous antibiotic therapies reduced the efficacy of LAC, to the level of RMT. Dyspeptic symptoms in the Gastrointestinal Symptoms Rating Scale (GSRS) were decreased by 30.5%. In logistic regression analysis, duodenal ulcer, gastric antral neutrophilic inflammation and age from 50 to 59 years independently predicted greater decrease in dyspeptic symptoms. In the gastric body, smokers had milder inflammation and less atrophy and in the antrum denser H. pylori load. Smokers also had lower IgG antibody titres against H. pylori and a smaller proportional decrease in antibodies after successful eradication. Smoking tripled the risk of duodenal ulcers. Conclusions: in Finland H. pylori resistance to clarithromycin is low, but metronidazole resistance among women is high making metronidazole-based therapies unfavourable. Thus, LAC is the best choice for first-line eradication therapy. The effect of eradication on dyspeptic symptoms was only modest. Smoking slows the progression of atrophy in the gastric body.

Possible application of carbon nanotube bundles for low temperature sensing

We report on the R-T measurement of carbon nanotube bundles from room temperature down to 1 K. The resistance at a particular temperature depends on the diameter of the bundle. The larger the bundle diameter is, the lower the value of the resistance. The resistance increases with the decrease in temperature as in the case of carbon, carbon glass resistance thermometer, and carbon nanotubes reported in the literature. The rate of the variation of resistance depends on the resistance of the bundle at room temperature which can be explored for the low temperature thermometry. Overall, the resistance and the sensitivity of the bundle depend on the bundle diameter which can be monitored easily.

Simplified theory of carrier back-scattering in semiconducting carbon nanotubes: A Kane's model approach

We present a simplified yet analytical formulation of the carrier backscattering coefficient for zig-zag semiconducting single walled carbon nanotubes under diffusive regime. The electron-phonon scattering rate for longitudinal acoustic, optical, and zone-boundary phonon emissions for both inter- and intrasubband transition rates have been derived using Kane's nonparabolic energy subband model.The expressions for the mean free path and diffusive resistance have been formulated incorporating the aforementioned phonon scattering. Appropriate overlap function in Fermi's golden rule has been incorporated for a more general approach. The effect of energy subbands on low and high bias zones for the onset of longitudinal acoustic, optical, and zone-boundary phonon emissions and absorption have been analytically addressed. 90% transmission of the carriers from the source to the drain at 400 K for a 5 mu m long nanotube at 105 V m(-1) has been exhibited. The analytical results are in good agreement with the available experimental data. (c) 2010 American Institute of Physics.

Molecular Basis for the Role of Staphylococcus aureus Penicillin Binding Protein 4 in Antimicrobial Resistance

Penicillin binding proteins (PBPs) are membrane-associated proteins that catalyze the final step of murein biosynthesis. These proteins function as either transpeptidases or carboxypeptidases and in a few cases demonstrate transglycosylase activity. Both transpeptidase and carboxypeptidase activities of PBPs occur at the D-Ala-D-Ala terminus of a murein precursor containing a disaccharide pentapeptide comprising N-acetyl-glucosamine and N-acetyl-muramic acid-L-Ala-D-Glu-L-Lys-D-Ala-D-Ala. beta-Lactam antibiotics inhibit these enzymes by competing with the pentapeptide precursor for binding to the active site of the enzyme. Here we describe the crystal structure, biochemical characteristics, and expression profile of PBP4, a low-molecular-mass PBP from Staphylococcus aureus strain COL. The crystal structures of PBP4-antibiotic complexes reported here were determined by molecular replacement, using the atomic coordinates deposited by the New York Structural Genomics Consortium. While the pbp4 gene is not essential for the viability of S. aureus, the knockout phenotype of this gene is characterized by a marked reduction in cross-linked muropeptide and increased vancomycin resistance. Unlike other PBPs, we note that expression of PBP4 was not substantially altered under different experimental conditions, nor did it change across representative hospital- or community-associated strains of S. aureus that were examined. In vitro data on purified recombinant S. aureus PBP4 suggest that it is a beta-lactamase and is not trapped as an acyl intermediate with beta-lactam antibiotics. Put together, the expression analysis and biochemical features of PBP4 provide a framework for understanding the function of this protein in S. aureus and its role in antimicrobial resistance.