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The Met Office Global and Regional Ensemble Prediction System–Global (MOGREPS‐G) used an ensemble transform Kalman filter (ETKF) to perturb its initial conditions from its operational implementation in September 2008 until December 2019. In 2019, MOGREPS‐G became the first operational atmospheric ensemble to apply hybrid four‐dimensional ensemble variational data assimilation (En‐4DEnVar) to each of the 44 perturbed ensemble members. Other enhancements have also been added, including to the inflation used to improve ensemble spread. The combined impact of these changes on ensemble forecasts is overwhelmingly positive but initially more neutral for deterministic forecasts, which also use the ensemble to represent flow‐dependent forecast errors in their hybrid data assimilation updates. The latter result is not a surprise, because the deterministic forecast's hybrid data assimilation was initially weighted more strongly to the modelled stationary covariance component and not optimised to take full advantage of the upgraded ensemble. A subsequent operational upgrade in December 2020 has introduced shifting in addition to lagging to exploit the ensemble better in the deterministic forecast's hybrid data assimilation by including ensemble members from a previous cycle and also from adjacent forecast lead times to augment the ensemble without having to run additional forecasts. More weight has since been given to the ensemble in the deterministic forecast's hybrid data assimilation in May 2022. A key motive for adopting hybrid 4DEnVar in MOGREPS‐G is to reduce maintenance overheads by virtue of sharing much of the deterministic forecast system's data assimilation code. This also enables the ensemble to assimilate almost all observation types used by the deterministic forecast. The updated system also exploits parallelism better so as to be fast enough for operational use, despite assimilating more observations and being more computationally expensive than the Met Office's ETKF. [ABSTRACT FROM AUTHOR]

The Met Office held a testbed over winter 2020/2021 where a new numerical weather prediction (NWP) sub‐km ensemble was set up on‐demand in response to interesting weather phenomena in the United Kingdom. The domain for the model was chosen in real time by a community of Met Office Research Scientists and Operational Meteorologists and over a 4‐month period the ensemble was triggered for nine events. The purpose of the testbed was to investigate whether a real‐time weather regime‐based enhancement in NWP capability was feasible, to understand what benefits a testbed environment might give, and to explore the practicalities of running such an event. Case studies from the testbed demonstrated that forecast ensembles at 2.2 km and 300 m grid spacing were able to capture observed winter weather, with greater spatial detail apparent, especially over complex orography, in the 300‐m model. Ensemble spread appeared less influenced by resolution, potentially due to the size of the domains tested or the weather regimes of the case studies. The testbed also showcased underutilized observations and additional radiosonde ascents were conducted. All the testbed meetings were conducted virtually due to COVID‐19 restrictions, and decisions were made about when to trigger the event using an online message board. The winter 2020/2021 testbed provides ideas for how on‐demand weather‐dependent testbeds might be conducted in the future. However, several recommendations are made that would enhance testbed benefits further, including more dedicated resource, stronger technology and data visualization and greater participation from both academia and weather information users. [ABSTRACT FROM AUTHOR]

Soil tests can help optimize nitrogen (N) fertilizer rates, thereby improving farmer profitability and environmental performance. In US Midwest maize (Zea mays) production, however, most soil N tests have limited accuracy to predict N fertilizer requirements. Here we tested the individual and combined ability of 30 soil tests (12 rapid N extractions, seven biological carbon or N tests, six long‐term incubation kinetic parameters, and five other routine soil tests), as well as environmental and management data, to predict maize response to N fertilizer across 56 site‐years in the US Midwest. Out of 30 soil tests, and across all site‐years, a 14‐d aerobic incubation best predicted whether maize responded to N fertilizer, and a 5‐min tetraphenyl borate extraction best predicted agronomic optimum N rate. We combined these two tests to evaluate their ability to predict N fertilizer response against the most commonly used soil N test in the US Midwest, the pre‐sidedress or late‐spring nitrate test (PSNT or LSNT). The combination of soil tests nearly doubled the ability to predict nonresponsive sites compared to PSNT, and on average resulted in a 40% reduction in over‐application and 37% reduction in under‐application of N fertilizer. Weather and management variables marginally improved the prediction of maize N response. Our results indicate that a simple combination of biological N mineralization (14‐d aerobic incubation) and chemical extraction (5‐min tetraphenyl borate) assays could improve current N fertilizer recommendations. [ABSTRACT FROM AUTHOR]

Background The need for a better understanding of pulmonary diseases has led to increased interest in the development of realistic computational models of the human lung. Methods To minimize computational cost, a reduced geometry model is used for a model lung airway geometry up to generation 16. Truncated airway branches require physiologically realistic boundary conditions to accurately represent the effect of the removed airway sections. A user-defined function has been developed, which applies velocities mapped from similar locations in fully resolved airway sections. The methodology can be applied in any general purpose computational fluid dynamics code, with the only limitation that the lung model must be symmetrical in each truncated branch. Results Unsteady simulations have been performed to verify the operation of the model. The test case simulates a spirometry because the lung is obliged to rapidly perform both inspiration and expiration. Once the simulation was completed, the obtained pressure in the lower level of the lung was used as a boundary condition. The output velocity, which is a numerical spirometry, was compared with the experimental spirometry for validation purposes. Conclusions This model can be applied for a wide range of patient-specific resolution levels. If the upper airway generations have been constructed from a computed tomography scan, it would be possible to quickly obtain a complete reconstruction of the lung specific to a specific person, which would allow individualized therapies. [ABSTRACT FROM AUTHOR]

Coronary artery disease (CAD) is the leading single cause of death in Australia affecting around 1.4 million people. Coronary computed tomography angiography has an established role in the assessment of patients with low to intermediate pretest probability for CAD who have chest pain and is typically used with the aim to rule out significant coronary artery stenosis. Use was initially limited because of concerns over radiation exposure, a Medicare rebate restricted to specialist referrals and an absence of data supporting its use as an alternative to functional testing in patients with chest pain. Recent advances in scanner technology and image sequencing, along with data from randomised control trials, have addressed these issues and indicate that coronary computed tomography angiography will play a greater role in the assessment of CAD in the coming years. [ABSTRACT FROM AUTHOR]

The antipsychotic drug olanzapine is widely prescribed to treat schizophrenia and other psychotic disorders. However, it often causes unwanted side effects, including diabetes, due to disruption of insulin-dependant glucose metabolism through a mechanism yet to be elucidated. To determine if olanzapine can affect the first step in glucose metabolism – glucose transport inside cells – we investigated the effect of this drug on the transport activity of a model glucose transporter. The glucose transporter from Staphylococcus epidermidis (GlcP Se ) is specific for glucose, inhibited by various human glucose transporter (GLUT) inhibitors, has high sequence and structure homology to GLUTs, and is readily amenable to transport assay, mutagenesis, and computational modeling. We found that olanzapine inhibits glucose transport of GlcP Se with an IC 50 0.9 ± 0.1 mM. Computational docking of olanzapine to the GlcP Se structure revealed potential binding sites that were further examined through mutagenesis and transport assay to identify residues important for olanzapine inhibition. These investigations suggest that olanzapine binds in a polar region of the cytosolic part of the transporter, and interacts with residues R129, strictly conserved in all GLUTs, and N136, conserved in only a few GLUTs, including the insulin-responsive GLUT4. We propose that olanzapine inhibits GlcP Se by impeding the alternating opening and closing of the substrate cavity necessary for glucose transport. It accomplishes this by disrupting a key salt bridge formed by conserved residues R129 and E362, that stabilizes the outward-facing conformation of the transporter. [ABSTRACT FROM AUTHOR]

Robust automated vortex detection algorithms are needed to facilitate the exploration of large-scale turbulent fluid flow simulations. Unfortunately, robust non-local vortex detection algorithms are computationally intractable for large data sets and local algorithms, while computationally tractable, lack robustness. We argue that the deficiencies inherent to the local definitions occur because of two fundamental issues: the lack of a rigorous definition of a vortex and the fact that a vortex is an intrinsically non-local phenomenon. As a first step towards addressing this problem, we demonstrate the use of machine learning techniques to enhance the robustness of local vortex detection algorithms. We motivate the presence of an expert-in-the-loop using empirical results based on machine learning techniques. We employ adaptive boosting to combine a suite of widely used, local vortex detection algorithms, which we term weak classifiers, into a robust compound classifier. Fundamentally, the training phase of the algorithm, in which an expert manually labels small, spatially contiguous regions of the data, incorporates non-local information into the resulting compound classifier. We demonstrate the efficacy of our approach by applying the compound classifier to two data sets obtained from computational fluid dynamical simulations. Our results demonstrate that the compound classifier has a reduced misclassification rate relative to the component classifiers. [ABSTRACT FROM AUTHOR]

SUMMARY Finite volume methods on structured and unstructured meshes commonly use second-order, upwind-biased linear reconstruction schemes to approximate the convective terms. Limiters are employed to reduce the inherent variable overshoot and undershoot of these schemes in discontinuous regions; however, they also can significantly increase the numerical dissipation of a solution in smooth regions. This paper presents a novel nonlocal, nonmonotonic (NLNM) limiter developed by enforcing cell minima and maxima on dependent variable values projected to cell faces. The minimum and maximum values for a cell are determined primarily through recursive reference to the minimum and maximum values of its upwind neighbors. The new limiter has been implemented into an existing flow solver. Various test cases are presented, which highlight the ability of the NLNM limiter to eliminate nonphysical oscillations while maintaining negligible levels of limiter-induced dissipation into the solution. Results from the new limiter are compared with those from other limited and unlimited second-order upwind and first-order upwind schemes. For the cases examined in the study, the NLNM limiter was found to improve accuracy without significantly decreasing overall simulation efficiency and robustness.Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Background: Takotsubo cardiomyopathy (TC) is increasingly recognised in patients presenting with features of acute coronary syndrome. We present a single centre experience of TC with medium term follow up. Methods: Fifty-two consecutive patients presenting with a diagnosis of TC were included. The clinical presentation, complications, baseline and follow-up echocardiograms and cardiac magnetic resonance imaging were analysed. Results: Fifty-one patients were female. A stressful event preceded presentation in 37 (71%) patients. Chest pain was the most common symptom (83%). Two patients presented with an out-of-hospital cardiac arrest. ST segment elevation (40%) and global T wave inversion (44%) were the most frequent electrocardiogram changes. Left ventricular assessment demonstrated typical apical ballooning in 41 patients and 11 patients demonstrated the mid-wall variant. In-hospital complications occurred in 11 patients (21%) and included acute pulmonary oedema ( n = 2), cardiogenic shock ( n = 5); two of whom had a significant left ventricular outflow gradient, atrial fibrillation ( n = 1), left ventricular thrombus ( n = 2) and a cerebrovascular event ( n = 2). Left ventricular function at presentation and follow up was compared in 40 patients. The mean ejection fraction in this group at presentation was 47% (20-70%) compared with that at follow up of 63% (44-76%). There were no significant complications or recurrences at follow up. Conclusions: While TC is a reversible condition with low rates of complications and recurrence at follow up it is, as demonstrated in our cohort, associated with significant in-hospital morbidity in a proportion of patients. [ABSTRACT FROM AUTHOR]

Nitrogen fertilizer efficiency has a large influence on profit, energy efficiency, N losses to the environment, and greenhouse gas emissions in maize (Zea mays L.) production. Our purpose was to develop a robust decision-support tool to help inform N fertilizer recommendations and to compare performance of this tool relative to existing recommendation approaches. Maize-N is a simulation model for estimating economically optimum N fertilizer rates (EONR) for maize. The model estimates the EONR based on uptake efficiency of the applied N, expected yield response, market prices of grain and N fertilizer, and mechanistic components of soil N mineralization. Uptake efficiency and expected yield response are derived from a database of yield response to applied N from field experiments in the United States, Asia, and South America. The model is responsive to: (i) soil properties and indigenous soil N supply capacity, (ii) local climatic conditions and yield potential, (iii) crop rotation (including type and yield of previous crop), (iv) tillage method and timing of tillage operations, and (v) fertilizer formulation, application method, and timing. Validation of Maize-N across N management regimes and environments in the western U.S. Corn Belt indicated reasonable agreement between observed and measured values of EONR (RMSE of 2l kg N ha-1), which compares favorably with RMSE values of 33 to 61 kg N ha-1 for other methods based on empirical relationships derived from regional field tests in Kansas, Missouri, Nebraska, South Dakota, and Iowa. [ABSTRACT FROM AUTHOR]

Nitrogen use efficiency (NUE) is of economic and environmental importance. Components of NUE were evaluated at in 32 irrigated corn (Zea mays L.) trials conducted across Nebraska with different N rates and where the previous crop was either corn (CC), drybean (Phaseolus vulgaris L.) (CD), or soybean [Glycine max (L.) Merr.] (CS). The mean grain yield with adequate nutrient availability was 14.7 Mg ha-1 When no N was applied, measured soil properties and irrigation water N accounted for <20% of the variation in plant nitrogen uptake (UN). Mean fertilizer N recovery in aboveground biomass was 74% at the lowest N rate compared with 40% at the highest N rate, a mean of 64% at the economically optimal nitrogen rate (EONR), and least with CD. Agronomic efficiency of fertilizer N averaged 29 kg grain kg-1 N at EONR and was also least with CD. Partial factor productivity of N averaged 100 kg grain kg-1 N at EONR, and was greater with CS compared with CC and CD. After harvest, residual soil nitrate nitrogen (RSN) in the 0- to 1.2-m depth ranged from 21 to 121 kg ha-1 and increased with N rate. Mean RSN was 88, 59, and 59 kg ha-1 for CD, CC, and CS, respectively. High corn yields can be achieved with high NUE and low RSN by management to maximize profitability in consideration of yield potential, and by applying N at the right amount and time. [ABSTRACT FROM AUTHOR]

Eur J Clin Invest 2010; 40 (2): 139–147 Aim The study assessed the benefit of high bolus dose tirofiban (HD-tirofiban) with enoxaparin compared with HD-tirofiban with unfractionated heparin (UFH). The study examined markers of platelet activation, thrombin generation and inflammation. Materials and methods The study is a prospective single centre open-label trial of patients with high-risk acute coronary syndrome treated with percutaneous intervention (PCI) who were randomized to anticoagulation with UFH or enoxaparin with HD-tirofiban (25 μg kg−1 bolus). This study measured a panel of platelet activation markers, inflammatory biomarkers and thrombus generation between the two groups. Result Sixty patients undergoing high-risk PCI were enroled in the study. Platelet inhibition as assessed by whole blood aggregometry following HD-tirofiban infusion was similar in both the UFH and enoxaparin groups. CD40 ligand expression on platelets was significantly reduced following PCI with HD-tirofiban and either UFH or enoxaparin. Following PCI, there were significant reductions measured in other markers of platelet activation including PAC-1, P selectin, factor V/Va, platelet-monocyte aggregates and monocyte expression of Mac-1 as determined by analysis of venous blood samples using flow cytometry. Prothrombin fragment 1+2, D-dimer, von Willebrand factor and high sensitive C-reactive protein levels were significantly less post PCI in the enoxaparin group compared with those patients receiving UFH. Conclusion The combination of HD tirofiban with enoxaparin resulted in an attenuated inflammatory response when compared with that of the combination of HD tirofiban with UFH. [ABSTRACT FROM AUTHOR]

The relationship between yield loss and disease severity can differ widely between crops. This has given rise to the concept of disease tolerance, with some crops exhibiting a smaller yield loss under a given severity of disease than others. Genetic improvement to minimise yield loss under disease is an attractive goal, as it exerts little or no selection pressure on pathogen populations, and could form a useful component of durable disease management programmes. However, progress towards this end requires a thorough understanding of the phenotypic traits that influence the response of yield to disease, their genetic control and the possible trade-offs involved with other desirable agronomic characteristics. This paper examines the candidate crop traits that may confer tolerance of foliar disease in wheat and barley and reviews evidence of genetic variation in their expression. In wheat grown under the relatively low light conditions of North-West Europe, post-anthesis source (assimilate supply) and grain sink capacity (capacity for dry matter accumulation) appear to be closely balanced. Traits associated with maintaining post-anthesis radiation interception and radiation use efficiency in spite of disease may confer tolerance. The most promising traits include a larger flag leaf and compensatory increases in photosynthetic rate in non-infected parts of leaves. In barley, yield is often more strongly sink limited, and early-season disease management is required to protect the formation of potential grain sites. A wider range of potential traits may influence tolerance including compensatory adjustments in leaf growth and morphology, and differences in the sensitivity of tiller and spikelet mortality to photoassimilate supply. Different methods for quantifying tolerance are suggested depending on the trait of interest. [ABSTRACT FROM AUTHOR]

Pulmonary thromboembolism (PE) is the third most frequent cause of cardiovascular death after ischaemic heart disease and stroke. In fatal PE, 2/3 of patients die within first hour of presentation. There is a clinical impetus to rapidly recognize, risk-stratify and appropriately treat patients with acute severe PE. Current recommendations present conflicting classification systems, and there is often some confusion in the clinical evaluation and management of patients with acute severe PE. This review presents a series of real clinical cases, which illustrate the available treatment options, ranging from conservative therapy to thrombolysis through to percutaneous catheter fragmentation and open surgical embolectomy. We evaluate the evidence for the various strategies and propose an algorithm for clinicians with a focus on early risk stratification and timely referral. This is particularly relevant to regional and remote centres, as well as secondary and tertiary institutions. [ABSTRACT FROM AUTHOR]

Stable isotope analysis (SIA) and gut contents analysis (GCA) are commonly used in food web studies, but few studies analyse these data in concert. We used SIA (δ15N) and GCA (% composition) to identify diets and trophic position (TP) of six stream fishes and to compare TP estimates between methods. Ordination analysis of gut contents identified two primary trophic groups, omnivores and predators. Significant differences in TPGCA and TPSIA were similar in direction among-species and among-trophic groups; neither method detected seasonal changes in omnivore diets. Within-species TPGCA and TPSIA were similar except for one omnivore. TPGCA was less variable than TPSIA for predators, but variation between methods was similar for omnivores. While both methods were equally robust at discriminating trophic groups of fishes, TPSIA is less laborious to estimate and may facilitate cross-stream comparisons of food web structure and energy flow. [ABSTRACT FROM AUTHOR]

A great deal of information is available in the literature on the effects of nutrition on disease development in plants and crops. However, much of this information is contradictory and although it is widely recognised that nutrition can influence disease in crops, limited progress has been made in the manipulation of crop nutrition to enhance disease control. Achieving this aim requires a sound understanding of the effects of fertilisation on nutrient levels and availability in crop tissues, and in turn, how the nutrient status of such tissues influences pathogen infection, colonisation and sporulation. Some of these details are known for a number of crop plants under controlled conditions, but very little of this type of information is available for crops under field conditions. This review focuses on nitrogen, sulphur, phosphorus, potassium and silicon, examines the availability of these nutrients in plant tissues to support pathogen growth and development, and reviews the effects of the different nutrients on disease development. The review also examines the potential for manipulating crop nutrition to enhance disease control in conventional and organic cropping systems. [ABSTRACT FROM AUTHOR]

Crop intensification is often thought to increase greenhouse gas (GHG) emissions, but studies in which crop management is optimized to exploit crop yield potential are rare. We conducted a field study in eastern Nebraska, USA to quantify GHG emissions, changes in soil organic carbon (SOC) and the net global warming potential (GWP) in four irrigated systems: continuous maize with recommended best management practices (CC-rec) or intensive management (CC-int) and maize–soybean rotation with recommended (CS-rec) or intensive management (CS-int). Grain yields of maize and soybean were generally within 80–100% of the estimated site yield potential. Large soil surface carbon dioxide (CO2) fluxes were mostly associated with rapid crop growth, high temperature and high soil water content. Within each crop rotation, soil CO2 efflux under intensive management was not consistently higher than with recommended management. Owing to differences in residue inputs, SOC increased in the two continuous maize systems, but decreased in CS-rec or remained unchanged in CS-int. N2O emission peaks were mainly associated with high temperature and high soil water content resulting from rainfall or irrigation events, but less clearly related to soil NO3-N levels. N2O fluxes in intensively managed systems were only occasionally greater than those measured in the CC-rec and CS-rec systems. Fertilizer-induced N2O emissions ranged from 1.9% to 3.5% in 2003, from 0.8% to 1.5% in 2004 and from 0.4% to 0.5% in 2005, with no consistent differences among the four systems. All four cropping systems where net sources of GHG. However, due to increased soil C sequestration continuous maize systems had lower GWP than maize–soybean systems and intensive management did not cause a significant increase in GWP. Converting maize grain to ethanol in the two continuous maize systems resulted in a net reduction in life cycle GHG emissions of maize ethanol relative to petrol-based gasoline by 33–38%. Our study provided evidence that net GHG emissions from agricultural systems can be kept low when management is optimized toward better exploitation of the yield potential. Major components for this included (i) choosing the right combination of adopted varieties, planting date and plant population to maximize crop biomass productivity, (ii) tactical water and nitrogen (N) management decisions that contributed to high N use efficiency and avoided extreme N2O emissions, and (iii) a deep tillage and residue management approach that favored the build-up of soil organic matter from large amounts of crop residues returned. [ABSTRACT FROM AUTHOR]

1. We investigated the spatial (longitudinal position and reach geomorphology) and seasonal (spring and autumn) influences on the variation of δ13C among organic matter sources and consumers in a forested Piedmont river, South Carolina, U.S.A. 2. Six sites were sampled along a continuum and varied in basin area from approximately 30 to 300 km2. Sites fell into two geomorphic categories (i) high-gradient, rock bed (‘rock’) or (ii) low-gradient, sand bed (‘sand’) sites. 3. Variation in δ13C was more strongly related to reach geomorphology than longitudinal position. δ13C of biofilm and consumers was consistently enriched at rock sites. Leaf litter (i.e. coarse particulate organic matter, CPOM) δ13C did not vary with bed type. There was significant δ13C enrichment at rock sites for biofilm, seston, fine benthic organic matter (FBOM), and eight of nine consumer trophic guilds (e.g. grazing invertebrates, insectivorous fishes). δ13C of biofilm and four trophic guilds was also positively correlated with drainage area, but the magnitude of enrichment was less than between bed types. 4. δ13C was generally enriched in spring, but this varied among organic matter types, consumers, and by bed type. CPOM and seston were enriched in spring, FBOM was enriched in autumn, and biofilm showed no trend. Five consumer guilds were enriched in spring, and only one fish guild, generalised carnivores, showed enrichment of muscle tissue in autumn. 5. Consumer δ13C enrichment at rock sites suggests greater reliance on algal carbon than for consumers at sand sites, but we also found δ13C enrichment of biofilm at rock sites. Thus, differences in consumer δ13C between bed types could be related to (i) increased consumption of biofilm at rock compared with sand sites, or (ii) consumption of biofilm at rock sites that is enriched relative to biofilm at sand sites or (iii) both mechanisms. 6. δ13C signatures in local food webs appear to respond to processes operating at multiple spatial scales. Overall downstream enrichment of biofilm and consumers was disrupted by strong local effects related to bed morphology. These results suggest that human alteration of channel habitat will have corresponding effects on stream food webs, as assessed by changes in δ13C. [ABSTRACT FROM AUTHOR]

Assessment of net primary productivity of maize (Zea mays L.)-based agroecosystems is dependent on both above and belowground dry matter production that is ultimately returned to the soil as residue and decaying roots. Root to shoot ratio (R/S) is a parameter often used to estimate root biomass (RB) when shoot biomass is measured or estimated. The labor intensive nature of root sampling and wide variety of sampling techniques has lead to a paucity of maize RB data in the literature, and few researchers have endeavored to characterize R/S throughout an entire growing season. In this paper, the results of 45 maize root studies published in 41 journal articles are summarized and the data used to generate estimates of maize RB and R/S versus days after emergence (DAE). The data from these studies indicate that on average, RB was maximized just after anthesis at approximately 31 g plant-1 (13.6 g C plant-1) and that average R/S varied from a high of 0.68 at emergence to a low of 0.16 at physiological maturity. Net rhizodeposited C as a percentage of total net root- derived belowground Cat time of sampling (%NRC) was reported for 12 maize studies and varied between 5 and 62%. The wide variation in the %NRC was shown to be highly correlated with an index combining irradiance level, photoperiod, and ambient temperature, suggesting a strong dependence of net rhizodeposited C on rate of photosynthesis and soil respiration. The net belowground C deposition at maize physiological maturity is estimated as 29 ± 13% of shoot biomass C for maize that has not experienced stress. [ABSTRACT FROM AUTHOR]

Treatment of barley ( Hordeum vulgare) with 3 mm saccharin, applied as a foliar treatment to the first leaf or as a soil drench, provided significant control of powdery mildew ( Blumeria graminis f.sp. hordei) on first and second leaves. This was unlikely to be the result of a direct effect of saccharin on the fungus, as application of the chemical to first leaves 2 h before inoculation did not affect conidial germination or formation of appressoria. Saccharin treatment had no significant effect on plant growth, except for a reduction in total leaf area in plants treated with a saccharin drench 14 days before inoculation with mildew. Phenylalanine ammonia-lyase activity was reduced significantly in second leaves 18 and 48 h after inoculation in plants treated with saccharin 14 days earlier. Peroxidase activity increased significantly in plants challenged with mildew within 6 days of saccharin application, although changes were not apparent until 48 h after pathogen challenge. On these occasions, treatment with saccharin resulted in a 33% increase in peroxidase activity compared with controls. In plants inoculated 10 or 14 days after saccharin application, cinnamyl alcohol dehydrogenase (CAD) activity increased prior to, and 18, 24 and 48 h after, inoculation of the barley plants with mildew. CAD activity increased approximately twofold compared with controls. However, in contrast to peroxidase, CAD activity was significantly higher in saccharin-treated plants prior to and after inoculation with powdery mildew, suggesting that saccharin primes CAD activity prior to pathogen challenge. [ABSTRACT FROM AUTHOR]

The antifungal and fungicidal effects of two chemotypes of basil (Ocimum basilicum) oil and its major individual components were studied in a series ofin vitroandin vivoexperiments. Mycelial growth of the plant pathogenic fungusBotrytis fabaewas reduced significantly by both the methyl chavicol chemotype oil and the linalol chemotype oil, and the major individual components of the oils all reduced fungal growth, with methyl chavicol, linalol, eugenol and eucalyptol reducing growth significantly. Combining the pure oil components in the same proportions as found in the whole oil led to very similar reductions in fungal growth, suggesting that the antifungal effects of the whole oils were due primarily to the major components. When the fungus was exposed to the oils in liquid culture, growth was reduced by concentrations considerably smaller than those used in the Petri dish studies.Botrytis fabaeand the rust fungusUromyces fabaewere also controlledin vivo, with the whole oils of both chemotypes, as well as pure methyl chavicol and linalol, reducing infection of broad bean leaves significantly. Most effective control of fungal infection was achieved if the treatments were applied 3 h postinoculation. [ABSTRACT FROM AUTHOR]

Abstract In the incompatible interaction between the barley cultivar Hart (mlo allele) and the powdery mildew fungus Blumeria graminis DC. Speer f. sp. hordei Marchal, free spermidine and conjugated forms of putrescine and spermidine were found to accumulate 1–3 days following inoculation. The increase in free spermidine could be accounted for by increased activities of the biosynthetic enzymes ornithine decarboxylase (EC 4.1.1.17) and S-adenosylmethionine decarboxylase (EC 4.1.1.50). Activities of the transferase enzymes putrescine hydroxycinnamoyl transferase (EC 2.3.1.-) and tyramine feruloyl-CoA transferase (EC 2.3.1.-) were also increased in leaves of Hart inoculated with powdery mildew, as were activities of the polyamine catabolic enzymes diamine oxidase (DAO, EC 1.4.3.6) and polyamine oxidase (PAO, EC 1.4.3.4). The possible role of conjugated polyamines, and increases in DAO and PAO, in penetration based resistance to powdery mildew infection is discussed. [ABSTRACT FROM AUTHOR]

Abstract Polyamine levels and activities of enzymes of polyamine biosynthesis and catabolism were examined in the barley cultivar Delibes (Ml1al + Ml(Ab) ) reacting hypersensitively to the powdery mildew fungus, Blumeria graminis f. sp. hordei (race CC220). Levels of free putrescine and spermine and of conjugated forms of putrescine, spermidine and spermine were greatly increased 1–4 d following inoculation of barley with the powdery mildew. These changes in polyamine levels were accompanied by elevated activities of the polyamine biosynthetic enzymes ornithine decarboxylase (ODC), arginine decarboxylase (ADC) and S -adenosylmethionine decarboxylase (AdoMetDC) and the polyamine catabolic enzymes diamine oxidase (DAO) and polyamine oxidase (PAO). Activities of two enzymes involved in conjugating polyamines to hydroxycinnamic acids, putrescine hydroxycinnamoyl transferase (PHT) and tyramine feruloyl-CoA transferase (TFT) were also examined and were found to increase significantly 1–4 d after inoculation. The possibility that the increased levels of free spermine, increased polyamine conjugates, and increased DAO and PAO activities are involved in development of the hypersensitive response of Delibes to powdery mildew infection is discussed. [ABSTRACT FROM AUTHOR]

The antifungal and fungicidal effects of hyssop (Hyssopus officinalis) oil and its individual components were studied in a series of in vitro and in vivo experiments. Mycelial growth of the plant pathogenic fungi Pyrenophora avenae and Pyricularia oryzae was completely inhibited by 0.4% hyssop oil. Volatile components diffusing from agar medium containing 0.4% hyssop oil also completely inhibited the growth of these two fungi. Various components of hyssop oil (L-bornyl acetate, isopinocampheol and pinocamphone), used individually, reduced growth of P. avenae and, where combinations of individual components were used, any mixture containing isopinocampheol completely inhibited fungal growth. Growth of P. oryzae was less affected by individual components of the oil. Hyssop oil reduced germination of Botrytis fabae conidia and uredospores of Uromyces viciae-fabae, but in contrast to the data from in vitro experiments, its effects on pathogen infection were less clear cut. Thus, although 0.05% hyssop oil reduced rust infection of broad bean when applied 1, 2 or 3 days before, or 1 or 2 days after inoculation, its effects against barley powdery mildew and apple powdery mildew were variable. It is suggested that this variability might be the result of the volatile components of the oil diffusing away from leaf surfaces, thus reducing the concentration of active components on the leaf surface. [ABSTRACT FROM AUTHOR]

Ethokem (Midkem Agrochemicals, Northampton, UK) and Bond (Newman Agrochemicals, Cambridge, UK) completely inhibited linear growth of Pyricularia oryzae at 1 and 2% concentrations of the compounds and strongly inhibited growth of Pyrenophora avenae in vitro. Vapor Gard (Miller Chemical & Fertilizer Corporation, Hannover, PA, USA) was less effective with relatively little inhibition of P. oryzae, but was a more effective inhibitor of P. avenae. All three compounds decreased cell lengths of both pathogens and increased cell diameters of P. avenae. Vapor Gard and Ethokem did not significantly alter cell diameters of P. oryzae, but a highly significant increase was observed with Bond. Gross changes in hyphal morphology were observed including swollen shortened cells, granulation of the cytoplasm, increased branching and collapsed empty cells. Ethokem and Bond decreased growth rate and inhibited biomass production of P. avenae. [ABSTRACT FROM AUTHOR]

Effects were examined of barley powdery mildew (Erysiphe graminis f. sp. bordei) the major leaf protein, ribulose-1,5-bisphosphate carboxylase (RuBPCase), and other enzymes of CO2 assimilation, phosphoenolpyruvate carboxylase (PEPcase), and malic enzymes, and enzymes associated with RuBPCase in the reductive pentose phosphate pathway. Activity of RuBPCase per unit fresh weight of leaf was inhibited by infection from the first sample, 3 days after inoculation, to the last sample, 24 days after inoculation, when healthy control leaves were visibly senescing. The inhibition occurred because the amount of RuBPCase protein (measured specifically by an immunological technique) was reduced from 6 days after inoculation, at which time there was little protein remaining. Activity of PEPcase per unit fresh weight of leaf was initially stimulated by infection, but, thereafter, it was inhibited. Inhibition, like that also affecting malic enzymes (NAD) and (NADP), 3-phosphglycerate kinase, and glyceraldehydes-3-phosphate dehyrogenases (NAD) and (NADP), was associated with a decline in amounts of total soluble minus RuBPCase protein per unit fresh weight of leaf. Reduced amounts of leaf protein may be associated with reduced nitrate uptake by roots and fungal demand for nitrogen in mildewed plants. [ABSTRACT FROM AUTHOR]

Difluoromethylarginine (DFMA) and difluoromethylornithine (DFMO) are inhibitors of the polyamine biosynthetic enzymes arginine decarboxylase (ADC) and ornithine decarboxylase (ODC), respectively. DFMO is a potential fungicide acting on fungal ODC. This report examines the effects of DFMA and DFMO on polyamine concentrations and metabolism, and on the activities of enzymes of polyamine biosynthesis and breakdown in the mycorrhizal fungus Laccaria proxima. Data indicate that L. proxima possesses both ADC and ODC activities. DFMA depleted putrescine and did not inhibit ODC activity, incubation of mycelium with a [U-14C]arginine substrate led to [14C]putrescine formation; DFMA completely inhibited the formation of polyamines from [U-14C]arginine; DFMO inhibited bound biosynthetic enzyme activity and the formation of putrescine from [U-14C]ornithine. Therefore, L. proxima may not be susceptible to fungicidal DFMO application. [ABSTRACT FROM AUTHOR]

Photosynthesis and resistance to rust infection were studied in upper, uninfected leaves of broad bean, Vicia faba L., where the lower two leaves were infected with rust, Uromyces viciae-fabae (Pers.) Shroet. Following inoculation of the lower leaves, rates of net photosynthesis were significantly increased in the upper, uninfected, fully-developed leaves and the young developing leaves, compared to controls. In contrast, photosynthesis was substantially reduced in the lower, rusted leaves. When 14CO2 was fed to the upper, uninfected leaves of rusted plants, there was a considerable increase in labelled assimilate in those leaves, compared to controls. In addition, there was substantial movement of labelled assimilate into lower, rusted leaves, into young, developing leaves and into roots. On the other hand, there was a substantial reduction in labelled assimilates moving into shoot apices. Upper. uninfected leaves of rusted beans exhibited increased resistance to rust infection. Thus, the percentage leaf area covered with rust and the number of pustules per cm² were reduced in these leaves compared to controls. This resistance to rust infection was greatest when the upper leaves were challenged 1 d after inoculation of the lower leaves with rust and decreased with increasing time after inoculation of the lower leaves. Young, developing leaves on rusted beans also exhibited increased resistance to rust infection. When photosynthesis in the upper leaves was reduced to near control values or well below control values by shading, resistance to rust infection in those leaves was also reduced, although not in proportion to the reduction in photosynthesis. It is suggested that the increased photosynthesis in upper, uninfected bean leaves probably facilitates maximum expression of resistance to infection in those leaves. [ABSTRACT FROM AUTHOR]

Polyamine metabolism, lipoxygenase and catalase activities and ethylene production were examined in green-islands induced to form on detached barley leaves infected with the powdery mildew fungus, Erysiphe graminis f. sp. hordei Marchal. Several-fold increases in free polyamines were detected in green-islands, which could not be accounted for by changes in polyamine biosynthetic and degradative enzymes: a small increase in ornithine decarboxylase (ODC) activity, greatly decreased arginine decarboxylase (ADC) activity, virtually unchanged activity of S-adenosylmethionine decarboxylase (AdoMetDC) and greatly increased polyamine oxidase (PAO) activity. Changes in conjugated forms of polyamines suggest that elevated free polyamine concentrations might result from reductions in this pool. Green-island tissues displayed a reduced activity of lipoxygenase, unchanged catalase activity and a greatly lowered rate of ethylene production. Chlorophyll concentration and rates of photosynthesis and dark respiration were slightly increased in these tissues. In senescing regions of infected leaves, there was a small increase in free putrescine and spermine and a decrease in spermidine concentration, while concentrations of conjugated polyamines were substantially reduced. This was accompanied by an overall decrease in ODC and ADC activities and an increased activity of both AdoMetDC and PAO. These regions exhibited lowered lipoxygenase activity, greatly enhanced catalase activity and reduced rates of ethylene production. In addition, senescing regions exhibited a substantial reduction in chlorophyll concentration and the rate of photosynthesis, although dark respiration was similar to control values. These results support the view that green-islands represent areas of the infected leaf where senescence is retarded, biosynthetic activity is retained and in which polyamines may play an important role. [ABSTRACT FROM AUTHOR]

Uptake of the polyamine biosynthesis inhibitor, α-difluoromethylornithine (DFMO), by barley seedlings was examined. DFMO was taken up by intact roots and approached saturation at a rate of 780 mol m-12 g-1 d.wt. The uptake as a function of DFMO concentration in the external medium was biphasic, with Eadie-Hofstee transformations giving Km values for system 1 uptake of 1.61 mol m-3 and for system 2 uptake of 53.31 mol m-3. DFMO uptake was reduced in darkness and was greatly influenced by transpiration rate. The inhibitor was taken up from host cells by the powdery mildew fungus, Erysiphe graminis f.sp. hordei Marchal, and DFMO fed to roots, or to excised leaves at different times after inoculation, gave substantial control of mildew infection. [ABSTRACT FROM AUTHOR]

summary: Growth and nutrient relations were examined in healthy leeks and in leeks inoculated with the rust, Puccinia allii, to give three different intensities of infection (i.e. 10, 20 and 30%). Experiments were conducted over an 8‐week experimental period, although only data from 5 weeks after inoculation are shown. The dry weights of rust‐infected plants were substantially reduced compared with controls over the entire experimental period. Although shoot: root (S: R) ratios were increased in rusted plants 2 weeks after inoculation, the trend was reversed thereafter and for the remainder of the experiment S:R ratio was reduced in comparison with healthy controls. The contents of nitrogen, phosphate, potassium and calcium were reduced in rusted plants compared to controls. On the other hand, with few exceptions, the concentrations and specific absorption rates of these minerals increased in rusted plants compared with healthy controls. The ability of infected plants to maintain a functional S:R equilibrium with respect to nutrient uptake was examined using an analysis based on comparing changes in incremental plant dry weight with incremental nutrient weight. Calculated values of functional equilibrium for control and rusted plants showed that rust infection altered functional equilibrium with respect to uptake of the four nutrients. The possible mechanisms underlying these changes in physiology and the analysis of such changes are discussed. [ABSTRACT FROM AUTHOR]

Photosynthesis was examined in discrete regions of leek (Allium porrum L.) leaves infected with the rust, Puccinia alli Rud. Oxygen evolution, expressed on both a chlorophyll and a leaf area basis, was significantly reduced in pustule regions, coupled with an increase in rates of dark respiration, for the duration of the experiment. The activity of ribulose bisphosphate carboxylase (RuBPcase) was reduced in pustule areas and losses in total soluble protein and chlorophyll were observed. Areas between pustules exhibited photosynthetic rates (on a chlorophyll basis) near to control values and dark respiration was reduced for at least part of the experiment. No significant alteration in RuBPcase activity, total soluble protein or chlorophyll concentrations was detected in interpustule regions. The physiological mechanisms underlying the changes in photosynthesis and respiration within discrete regions of rusted leeks are discussed. [ABSTRACT FROM AUTHOR]

The effects of the inhibitors of polyamine biosynthesis, 2-difluoromethylornithine (DFMO), (E)-2-(fluoromethyl) dehydroornithine (Δ-MFMO), (E)-2-(fluoromethyl) dehydroornithine methyl ester (Δ-MFMO CH3), 2-hydrazinoornithine, (2R,5R)-6-heptyne-2,5-diamine (RR-MAP), 2-difluoromethylarginine (DFMA), cyclohexylamine (CHA) and methylglyoxal-bis (guanylhydrazone) (MGBG) on infection of barley leaves (Hordeum vulgare L.) by Erysiphe graminis f.sp. hordei Marchal, were examined. Various concentrations of the inhibitors were sprayed onto barley leaves cv. Golden Promise as post-inoculation treatments. DFMO, MGBG and a combination of the two were also applied as pre-inoculation treatments. Each inhibitor substantially reduced mildew infection. DFMO was as efficient as the more recently developed ornithine analogues. With the exception of the DFMA treatments, post-inoculation sprays were more effective than pre-inoculation ones. When DFMO, MGBG and DFMA were sprayed onto leaves at different times, DFMO and MGBG most effectively controlled mildew when sprayed on the third day after inoculation. DFMA was more efficient as a pre-inoculation treatment. Addition of polyamines to DFMO sprays increased mildew infection, compared to that resulting from the DFMO treatment alone, but infection was less than in the controls. [ABSTRACT FROM AUTHOR]

The effects of the polyamine biosynthesis inhibitor, difluoromethylornithine (DFMO), on rust infection of the broad bean have been examined. DFMO was sprayed onto leaves at 0.025, 0.1 and 0.4 m[subM] before and after inoculation. DFMO was also applied to leaf halves in order to examine the possible translocation of the inhibitor to untreated leaf halves (systemic treatment). DFMO gave good control of rust infection, irrespective of the treatment. DFMO applied after inoculation was more effective than a pre-noculatory treatment when used in non-systemic tests. When used as a systemic treatment on leaf halves, pre-inoculatory application of DFMO was more effective. DFMO did not affect plant growth or endogenous concentrations of polyamines. The possible use of DFMO in the control of a range of plant diseases is discussed. [ABSTRACT FROM AUTHOR]

The concentrations of three amines (putrescine, spermidine and spermine) were much increased in first leaves of barley infected with powdery mildew, whilst the concentrations of putrescine and spermidine in roots of mildewed barley were significantly decreased. Although no significant change in the activities of three polyamine biosynthetic enzymes (ADC, arginine decarboxylase; ODC, ornithine decarboxylase; and SAMDC, S-adenosyl methionine decarboxylase) could be detected in roots of mildewed barley, the activities of ADC, ODC and SAMDC were increased in infected first leaves. The significance of these alterations in polyamines and their biosynthetic enzymes in mildewed barley is discussed. [ABSTRACT FROM AUTHOR]

The concentrations of three amines (putrescine, spermidine and spermine) are much increased in 'clubbed' regions of roots of turnip infected by Plasmodiophora brassicae, whilst the concentrations, particularly that of putrescine, decreased in regions of infected roots not exhibiting symptoms of clubroot development. The possible involvement of these polyamines in the formation of 'clubs' on infected roots is discussed. [ABSTRACT FROM AUTHOR]

The diamine putrescine and the polyamines spermidine and spermine are ubiquitous in nature and are essential for cell proliferation. Since polyamine biosynthesis in plants can start from either ornithine or arginine, while fungal polyamine biosynthesis appears to utilise only the ornithine route, it was suggested that specific inhibition of fungal polyamine biosynthesis should be lethal. Indeed, inhibitors of polyamine biosynthesis, e.g. the ornithine decarboxylase inhibitor α-difluoromethylornithine, have been shown to inhibit fungal growth in vitro and to control fungal infections on a variety of plants under glasshouse and field conditions. It is now known that polyamine analogues can perturb polyamine metabolism leading to powerful antiproliferative effects in cancer cells. This paper reviews the results of a research programme focused on the synthesis and evaluation of putrescine analogues as novel fungicides. A number of aliphatic, alicyclic and cyclic diamines have been shown to possess considerable fungicidal activity, but although many of these compounds perturb polyamine metabolism in fungal cells, such changes are not considered sufficient to account for the observed antifungal effects. More recent work on spermidine analogues is also described. [ABSTRACT FROM AUTHOR]

The Peyer's patches of the terminal ileum are a source of IgA plasma cells in the intestinal lamina propria of experimental animals. They are also thought to harbour IgA memory cells. However, the microanatomical location of Peyer's patch memory cells, and whether they are also present in man is not known. Human Peyer's patches have a pronounced marginal zone (MGZ) of sIgD-negative B cells. In this study we analysed the sequence of polymerase chain reaction-amplified, rearranged IgVH genes from microdissected MGZ B cells, to determine whether this is a site of B- cell memory in Peyer's patches. We observed that the majority of Peyer's patch MGZ B cells contain heavily mutated IgVH genes and are therefore clearly memory B cells. Sequences of rearranged mutated genes in the MGZ have a pattern of replacement and silent mutations expected of selected products of the affinity maturation process. Related clones, with identical CDR3 but different patterns of mutation, are seen. This suggests that either these memory cells are formed as the germinal centre selection process proceeds, or a memory cell has re-entered the germinal centre for further rounds of mutation. Interestingly, in one patient, the MGZ in the Peyer's patches also contains a proportion of B cells with unmutated IgVH 4.21 genes. [ABSTRACT FROM AUTHOR]

Mycelial growth, polyamine concentrations and the activities of enzymes of polyamine biosynthesis and catabolism were examined in Phytophthora infestans and Pythium ultimum grown in the presence of difluoromethylornithine (DFMO), an inhibitor of ornithine decarboxylase (ODC), and difluoromethylarginine (DFMA), an inhibitor of arginine decarboxylase (ADC). Growth of P. infestans was reduced by DFMO and a mixture of DFMO + DFMA, but was increased by DFMA at concentrations of 5mM and greater. Polyamine concentrations and ODC activity were significantly reduced in P. infestans grown on all inhibitor treatments. In contrast, growth, polyamine concentrations and enzyme activities were not affected in P. ultimum exposed to the inhibitors. It seems unlikely that P. infestans and P. ultimum possess ADC activity, as neither of the products of ADC activity (agmatine and putrescine) could be detected in ADC assays. Although ODC from P. infestans was sensitive to DFMO, ODC from P. ultimum was insensitive to the inhibitor. Moreover, uptake of DFMO by P. infestans was three times greater than that observed by P. ultimum. [ABSTRACT FROM AUTHOR]