bluuebunny/crossref_metadata_2025_split huggingface dataset:
NAD+‐dependent DNA ligases of Mycobacterium tuberculosis and Streptomyces coelicolor
Authors: Wilkinson Adam , Sayer Heather , Bullard Desmond , Smith Andrew , Day Jonathan , Kieser Tobias , Bowater Richard 
Published: April 2003

AbstractSequencing of the genomes of Mycobacterium tuberculosis H37Rv and Streptomyces coelicolor A3(2) identified putative genes for an NAD+‐dependent DNA ligase. We have cloned both open reading frames and overexpressed the protein products in Escherichia coli. In vitro biochemical assays confirm that each of these proteins encodes a functional DNA ligase that uses NAD+ as its cofactor. Expression of either protein is able to complement E. coli GR501, which carries a temperature‐sensitive mutation in ligA. Thus, in vitro and in vivo analyses confirm predictions that ligA genes from M. tuberculosis and S. coelicolor are NAD+‐dependent DNA ligases. Proteins 2003;51:321–326. © 2003 Wiley‐Liss, Inc.
Structure‐based identification of binding sites, native ligands and potential inhibitors for G‐protein coupled receptors
Authors: Cavasotto Claudio N. , Orry Andrew J.W. , Abagyan Ruben A. 
Published: April 2003

AbstractG‐protein coupled receptors (GPCRs) are the largest family of cell‐surface receptors involved in signal transmission. Drugs associated with GPCRs represent more than one fourth of the 100 top‐selling drugs and are the targets of more than half of the current therapeutic agents on the market. Our methodology based on the internal coordinate mechanics (ICM) program can accurately identify the ligand‐binding pocket in the currently available crystal structures of seven transmembrane (7TM) proteins [bacteriorhodopsin (BR) and bovine rhodopsin (bRho)]. The binding geometry of the ligand can be accurately predicted by ICM flexible docking with and without the loop regions, a useful finding for GPCR docking because the transmembrane regions are easier to model. We also demonstrate that the native ligand can be identified by flexible docking and scoring in 1.5% and 0.2% (for bRho and BR, respectively) of the best scoring compounds from two different types of compound database. The same procedure can be applied to the database of available chemicals to identify specific GPCR binders. Finally, we demonstrate that even if the sidechain positions in the bRho binding pocket are entirely wrong, their correct conformation can be fully restored with high accuracy (0.28 Å) through the ICM global optimization with and without the ligand present. These binding site adjustments are critical for flexible docking of new ligands to known structures or for docking to GPCR homology models. The ICM docking method has the potential to be used to “de‐orphanize” orphan GPCRs (oGPCRs) and to identify antagonists–agonists for GPCRs if an accurate model (experimentally and computationally validated) of the structure has been constructed or when future crystal structures are determined. Proteins 2003;51:423–433. © 2003 Wiley‐Liss, Inc.
Patch spraying: future role of electronics in limiting pesticide use
Authors: Miller Paul CH 
Published: April 2003

AbstractDevelopments relating to the control of application equipment can deliver improvements in pesticide use by better matching applications to target requirements. This may have components relating to the spatial distribution of a weed, pest or disease or methods by which the target, particularly a crop canopy, can be described with respect to a given application. Changes in application can relate to the dose and/or volume applied, but may also concern the way in which a treatment is delivered in terms of parameters such as spray trajectory angle and droplet size distribution. For many weed species there is evidence of patchy distributions in field situations. Studies have shown that savings of typically up to 40% in herbicide use can be achieved by adopting patch spraying approaches in such situations. Weed patch detection is key to the performance of such patch spraying systems. In widely spaced rowcrops such as vegetables, there is considerable scope for developing fully automated detection systems based on image analysis, and for the development of accurate guidance systems that apply pesticides only to the crop row. In crops with a relatively high plant density, weed detection in the medium/short term is likely to be based on manual discrimination. The costs of labour for manual weed patch mapping have been estimated at less than £1.50 ha−1. Potential savings in pesticide use can also be made if applications are matched to crop canopy structure. This is most important in bush and tree crops where savings of up to 75% in pesticide use could be achieved. In crops such as cereals, studies have shown that savings in fungicide use may be possible, particularly at earlier stages of growth by adjusting spray delivery to measured canopy characteristics. Key components of the performance of application systems concern the ability to deliver over a dose rate range of more than 3:1 while maintaining control of variables such as delivery trajectory angle and spray quality. Traceability and the effective monitoring of applications is likely to be a major driver influencing the uptake of more sophisticated control systems. Methods of labelling pesticides with systems that can be read by the application unit will be an important step in the development of recording and data handling systems that will operate safely with the minimum of operator input and enable the environmental advantages of targeted pesticide application to be monitored. Copyright © 2003 Society of Chemical Industry
Growing vegetables in developing countries for local urban populations and export markets: problems confronting small‐scale producers
Authors: Dinham Barbara 
Published: April 2003

AbstractVegetables attract high applications of pesticides, and farmers in developing countries use many acutely toxic insecticides to control pests on these crops. With the liberalisation of agricultural markets in developing countries, the number of small‐scale farmers growing vegetables for both domestic and export markets is increasing. Demand for supplies of year‐round and exotic fruit and vegetables has grown in industrialised countries, but with rising quality standards and traceability requirements it is difficult for small‐scale farmers to benefit from this lucrative non‐traditional agricultural export trade. The demand is high for vegetables in the expanding cities in developing countries, and farmers in peri‐urban areas, or rural areas with good access to the cities, are in a position to find a growing market for their produce. Poor storage facilities will often mean that farmers are forced to sell at peak times when prices are low. Farmers rarely have access to training in pesticide use, and have only limited or no access to advice on the complicated management of pesticides. The Food and Agriculture Organisation of the UN is concerned about high levels of poor quality and adulterated pesticides on sale in developing countries. Surveys repeatedly show that without training, farmers are unable to make good crop decisions: recognition of pests and their predators is generally low, leading to decisions to spray to kill any insect; knowledge of product selection, application rates and timing is poor; different products are often combined in the belief that the effect will be greater; re‐entry periods after spraying and essential harvest intervals are not known; and without knowledge of alternatives, farmers will often assume that the only solution to pest problems is to spray more frequently. From a consumer's point of view, few developing countries are able to monitor pesticide residues, particularly for produce grown for home consumption: most countries do not have laboratories for even simple residue testing. Changes in European Maximum Residue Limits means that export crops will be rejected if they contain residues at the Limit of Detection of pesticides not registered in Europe. Season‐long field level training in Integrated Pest Management can help farmers to become better decision‐makers, and to greatly reduce pesticide use while reducing risks to their own health and environment, producing safer products for consumers, maintaining yields, and increasing incomes. Copyright © 2003 Society of Chemical Industry
A critical evaluation of the role of alternative oxidase in the performance of strobilurin and related fungicides acting at the Qo site of Complex III
Authors: Wood Paul M , Hollomon Derek W 
Published: April 2003

AbstractMitochondrial respiration conserves energy by linking NADH oxidation and electron‐coupled proton translocation with ATP synthesis, through a core pathway involving three large protein complexes. Strobilurin fungicides block electron flow through one of these complexes (III), and disrupt energy supply. Despite an essential need for ATP throughout fungal disease development, strobilurins are largely preventative; indeed some diseases are not controlled at all, and several pathogens have quickly developed resistance. Target‐site variation is not the only cause of these performance difficulties. Alternative oxidase (AOX) is a strobilurin‐insensitive terminal oxidase that allows electrons from ubiquinol to by‐pass Complex III. Its synthesis is constitutive in some fungi but in many others is induced by inhibition of the main pathway. AOX provides a strobilurin‐insensitive pathway for oxidation of NADH. Protons are pumped as electrons flow through Complex I, but energy conservation is less efficient than for the full respiratory chain. Salicylhydroxamic acid (SHAM) is a characteristic inhibitor of AOX, and several studies have explored the potentiation of strobilurin activity by SHAM. We present a kinetic‐based model which relates changes in the extent of potentiation during different phases of disease development to a changing importance of energy efficiency. The model provides a framework for understanding the varying efficacy of strobilurin fungicides. In many cases, AOX can limit strobilurin effectiveness once an infection is established, but is unable to interfere significantly with strobilurin action during germination. A less stringent demand for energy efficiency during early disease development could lead to insensitivity towards this class of fungicides. This is discussed in relation to Botrytis cinerea, which is often poorly controlled by strobilurins. Mutations with a similar effect may explain evidence implicating AOX in resistance development in normally well‐controlled plant pathogens, such as Venturia inaequalis. Copyright © 2003 Society of Chemical Industry
Contribution of contact toxicity and wheat condition to mortality of stored‐product insects exposed to spinosad
Authors: Toews Michael D , Subramanyam Bhadriraju 
Published: April 2003

AbstractSpinosad, a reduced‐risk commercial insecticide derived from a bacterial fermentation product, possesses both contact and oral toxicities against insects. Contact toxicity of spinosad to adults of Rhyzopertha dominica (F), Sitophilus oryzae (L), and Tribolium castaneum (Herbst) was evaluated by exposure for 24 or 48 h to treated glass Petri dishes. Adults were exposed to different deposits (0.001–0.79 mg cm−2) of spinosad in 24‐h tests and to deposits of 0, 0.0016 and 0.016 mg cm−2 in 48‐h tests. Rhyzopertha dominica was most susceptible to spinosad in 24‐ and 48‐h tests, followed by S oryzae, and T castaneum. The 24‐h LD50 values were 0.0004, 0.077 and 0.189 mg cm−2 for R dominica, S oryzae, and T castaneum, respectively. All R dominica adults were dead following 48 h exposure to both spinosad deposits, whereas mortality of S oryzae and T castaneum ranged from 10 to 85% and 12 to 48%, respectively. Rhyzopertha dominica, T castaneum, and O surinamensis adults were exposed for 14 days to whole wheat, cracked wheat and wheat flour treated with 0, 0.1 and 1.0 mg kg−1 of spinosad. Rhyzopertha dominica adults were highly susceptible to spinosad, followed by O surinamensis and T castaneum. Immatures (eggs and larvae) of T castaneum and O surinamensis exposed for 14 days were more susceptible on spinosad‐treated whole wheat than on treated cracked wheat and wheat flour. This is the first report documenting contact activity of spinosad, and the effect of grain condition on spinosad toxicity, to stored‐product insects. Copyright © 2003 Society of Chemical Industry
Evaluation of probabilistic risk assessment of pesticides in the UK: chlorpyrifos use on top fruit
Authors: Crane Mark , Whitehouse Paul , Comber Sean , Watts Chris , Giddings Jeffrey , Moore Dwayne RJ , Grist Eric 
Published: April 2003

AbstractThe use of probabilistic risk assessment (PRA) for examining chemical impacts has become an important area of debate within the European Union. This paper describes a case study on probabilistic techniques to assess pesticide risks in the UK aquatic environment. The main aim of this paper is to demonstrate both the potential strengths and weaknesses of PRA for assessing pesticides when compared with the conventional deterministic approach, and to examine whether PRA is useful within the European regulatory context. The organophosphate insecticide, chlorpyrifos, was selected as a model compound and toxicity exposure ratios calculated using Monte Carlo analysis and different distributions of spray drift and toxicity values following application to top fruit. Chlorpyrifos is highly toxic to arthropods but less toxic to fishes. Species sensitivity followed a log‐normal distribution when fitted to all toxicity data. Toxicity data quantity had little influence on species sensitivity distribution model parameters when n was greater than 10 species. Below this, estimates were less accurate and precise, possibly because of the inclusion of data from many different sources. Estimates of chlorpyrifos exposure derived from the standard spray drift model differed substantially from measurements of chlorpyrifos in European surface waters. When a distribution based on measured concentrations was used in a PRA, the risk of acute fish mortality was low, and the risk of acute arthropod mortality was lower than in other scenarios, although not negligible. If PRA is used to assess pesticides, risk managers need further guidance on how to conduct a PRA and what constitutes ‘unacceptable risk’ under EC Directive 91/414/EEC, as judgement is required when simple trigger values are no longer used. Copyright © 2003 Society of Chemical Industry
Adsorption–desorption of metalaxyl as affecting dissipation and leaching in soils:role of mineral and organic components
Authors: Fernandes Maria C , Cox Lucía , Hermosín María C , Cornejo Juan 
Published: April 2003

AbstractAdsorption–desorption studies of metalaxyl in fifteen agricultural soil samples from Southern Portugal and Spain were performed following a batch equilibration method. Very high sorption was observed on a clay soil of high content in altered illite, but, when this soil was excluded from regression analysis, organic matter (OM) was the most important single soil property affecting sorption at low concentrations of metalaxyl. At higher concentrations, no correlation was observed with any soil property. The relevance of OM on sorption was also corroborated by the increase in sorption coefficients when soil OM was increased artificially by the addition of an organic amendment. Sorption studies with the colloidal fraction of selected soils also revealed the importance of mineral surfaces in metalaxyl sorption. Sorption of metalaxyl in most of the soil samples was hysteretic. Selected soil samples were incubated in the dark, sampled periodically and extracted for their fungicide content. Metalaxyl half‐lives increased with sorption and OM content of the soil, and were specially high in the amended soil. Leaching studies in hand‐packed columns under saturated/unsaturated flow conditions showed an inverse relation between leaching and sorption. Recoveries from the soil columns were close to 80% of the metalaxyl applied, except for the soil which OM was artificially increased, in which recovery was lower and this has been attributed to the much higher irreversibility of metalaxyl sorption in the amended soil. Copyright © 2003 Society of Chemical Industry
Variations in acaricidal effect of wettable sulfur on Tetranychus urticae (Acari: Tetranychidae): effect of temperature, humidity and life stage
Authors: Auger Philippe , Guichou Sabine , Kreiter Serge 
Published: April 2003

AbstractUnder laboratory conditions, the acaricidal effect of wettable sulfur is influenced by climatic conditions and the stage of development of Tetranychus urticae. Its ovicidal effect results from the combined action of temperature and relative humidity (RH). Wettable sulfur becomes effective at 27.5 °C and 75% RH. Beyond this threshold, the acaricidal effect increases with rising temperature or humidity, to become complete at a temperature of 35 °C and 90% RH. Within the range of temperatures and humidities 20 °C/30% RH and 35 °C/90% RH the mortality of immatures (from protonymphs to teleiochrysalis) was total. Under similar experimental conditions, females usually died before the end of the experiment. Temperature and relative humidity increased the adulticidal potential of wettable sulfur. The fecundity of the sulfur‐treated females and the viability of their progeny was found to depend on temperature and RH. According to the same climatic conditions, eggs were less susceptible than females, which were in turn less susceptible than juvenile stages. Copyright © 2003 Society of Chemical Industry
Development of a bioassay system for monitoring susceptibility in Thrips tabaci
Authors: Rueda Alfredo , Shelton Anthony M 
Published: April 2003

AbstractA system is described for collecting adult and larva of Thrips tabaci from onion foliage into insecticide‐treated vials to evaluate susceptibility to insecticides. The thrips insecticide bioassay system (TIBS) allows one to treat vials and store them for 3 weeks before thrips are collected. Depending on the population density in the field, collection of the insects for the test required from 3–6 h for one person. Assays are read after 24 h. This system was used in 1997 and 1998 in commercial onion fields in Honduras and Nicaragua, and TIBS was sensitive enough to detect differences to the insecticides tested, to thrips life stages and to different generations within an onion‐growing season. Data collected suggest that there were not serious problems with thrips insecticide resistance, with the possible exception of cypermethrin in Nicaragua which had a resistance ratio (RR) value of 26.9 for adult thrips. The largest RR values were observed at the end of the growing season, and this may be caused by the season‐long selection by insecticide sprays. The mortality of adults and larvae followed the same general pattern, but the ratio between larvae and adults differed for each chemical group. Copyright © 2003 Society of Chemical Industry
Pesticide degradation in a ‘biobed’ composting substrate
Authors: Fogg Paul , Boxall Alistair BA , Walker Allan , Jukes Andrew A 
Published: April 2003

AbstractPesticides play an important role in the success of modern farming and food production. However, the release of pesticides to the environment arising from non‐approved use, poor practice, illegal operations or misuse is increasingly recognised as contributing to water contamination. Biobeds appear to offer a cost‐effective method for treating pesticide‐contaminated waste. This study was performed to determine whether biobeds can degrade relatively complex pesticide mixtures when applied repeatedly. A pesticide mixture containing isoproturon, pendimethalin, chlorpyrifos, chlorothalonil, epoxiconazole and dimethoate was incubated in biomix and topsoil at concentrations to simulate pesticide disposal. Although the data suggest that interactions between pesticides are possible, the effects were of less significance in biomix than in topsoil. The same mixture was applied on three occasions at 30‐day intervals. Degradation was significantly quicker in biomix than in topsoil. The rate of degradation, however, decreased with each additional treatment, possibly due to the toxicity of the pesticide mixture to the microbial community. Incubations with chlorothalonil and pendimethalin carried out in sterile and non‐sterile biomix indicated that degradation, rather than irreversible adsorption to the matrix, was the main mechanism responsible for the reduction in recovered residues. Results from these experiments suggest that biobeds offer a viable means of treating pesticide waste. Copyright © 2003 Society of Chemical Industry
Pesticide buffer zones for the protection of wildlife
Authors: Burn Alastair 
Published: April 2003

AbstractBuffer zones can play important roles in agricultural habitats, both in the protection of off‐crop habitats from pesticide and fertiliser drift and run‐off, and in providing important areas of non‐crop habitats. Their role in the protection of aquatic habitats from pesticide drift is a significant feature of pesticide risk management, but they are currently used only to a limited degree to protect terrestrial habitats. This paper summarises some of the evidence for the risks and impacts of pesticide drift into non‐crop habitats, and the approaches taken by the nature conservation agencies in deriving buffer zones for the protection of sites that are important for nature conservation. Biodiversity objectives need to be explicitly built into ICM programmes, and buffer zones, together with appropriate application technology, can play an important part in reducing pesticide drift in ICM systems to achieve such objectives. Copyright © 2003 Society of Chemical Industry
Pesticide usage in some vegetable crops in Great Britain: real on‐farm applications
Authors: Thomas Miles R 
Published: April 2003

AbstractThe last decade has seen an increasing requirement throughout the United Kingdom (UK) for accurate, timely information on pesticide usage on fresh produce such as vegetables to satisfy government legislation and provide data as part of the registration and review process of pesticides. These data, collected by the Department for Environment, Food and Rural Affair's Pesticide Usage Survey Group (PUSG), provide information on current and past usage patterns and allow the impact of use on the environment, operator and consumer to be more accurately assessed from actual usage patterns rather than worst‐case scenarios. Surveys of commercially grown carrot, Brussels sprouts and onion crops in Great Britain were undertaken at regular intervals between 1986 and 1999, using fully stratified samples of growers. Only on Brussels sprouts was there a significant decline in pesticide use over this period, but the frequency of treatments increased on all three crops, reflecting the recent introduction of more active molecules and lower dose rates. The implications for growers of EU Directive 91/44 are discussed if active ingredients are lost because they fail to achieve Annex 1 listing. © British Crown Copyright 2003. Reproduced with the permission of the Controller of Her Majesty's Stationery Office. Published for SCI by John Wiley & Sons, Ltd.