bluuebunny/crossref_metadata_2025_split huggingface dataset:
Natural products as a source of agrochemicals and leads for chemical synthesis
Authors: Pillmoor John B. , Wright Kenneth , Terry Adrian S. 
Published: November 2006

AbstractThe use of natural products as a source of new agrochemicals and the procedures that can be undertaken to discover such compounds are reviewed using examples from both the literature and our own experiences. The commercial successes obtained to date show that natural products are a powerful source of new agrochemicals. The results from a survey of the views of the agrochemical industry of natural product work indicated a high level of interest, with 16 of the 19 companies that replied being involved in natural product work either through in‐house or external programmes of work. Possible approaches to the key challenges of atural product work, for example choice of sources and screens, avoiding known metabolites and obtaining sufficient compound for biological evaluation, are discussed.
Plant products to control plant parasitic nematodes
Authors: Birch A. Nicholas E. , Robertson Walter M. , Fellows Linda E. 
Published: November 2006

AbstractPlants produce a wide range of defensive compounds (allomones) to protect themselves from predators and pathogens. Selected allomones have been screened against plant parasitic nematodes for a range of activities such as anti‐hatching, repellent, nematotoxic, anti‐feedant or anti‐viurs vectoring activities and inhibition of female development. Plant‐growth stimulation and anti‐nematode activities complementary to host‐plant resistance were also studied. Examples are presented of ways in which plant‐derived compounds can interfere with the life cycles of nematodes and their close relationships with host plants. The potential of plant‐derived compounds in future environmentally benign integrated pest management of nematodes is discussed.
Algae as a source of biologically active products
Authors: Cannell Richard J. P. 
Published: November 2006

AbstractAlgae are a large and diverse group of organisms from which a wide range of secondary metabolites have been isolated. A number of these compounds possess biological activity such as toxicity, antibacterial, antifungal, antiviral, antitumour and other specific activities. An indication of the range and diversity of algal metabolites and their biological activities is given and the potential of algae as a source of useful biologically active products is discussed.
Investigation of relative rates of solvent and solute penetration through protective glove materials
Authors: Watkinson Adam C. , Brain Keith R. , Walters Kenneth A. , Hadgraft Jonathan 
Published: November 2006

AbstractPesticides are often formulated as a concentrate in volatile organic solvents. The most important means of preventing the contamination of workers using the concentrate is by the use of protective clothing, particularly gloves. The influence of formulation solvent on solute permeation rates across selected protective glove materials has been investigated. In one of the cases studied, the solute penetrated the glove material appreciably faster than the formulation solvent. This result, therefore, questions the manner in which gloves are often selected for protection against pesticide formulations (by selecting the glove that offers the best protection against the formulation solvent rather than the active ingredient). Although this is a preliminary study, it is recommended that, to gain the maximum protective effect, all selected gloves are tested using the formulation of choice and that the permeation of all components of the formulation is monitored and reported. It may, therefore, be necessary for glove and pesticide manufacturers to re‐examine the way in which these tests are carried out and the processes of product selection used.
Chemical precursors for studying the effects of glucosinolate catabolites on diseases and pests of oilseed rape (Brassica napus) or related plants
Authors: Dawson Glenn W. , Doughty Kevin J. , Hick Alastair J. , Pickett John A. , Pye Barry J. , Smart Lesley E. , Wadhams Lester J. 
Published: November 2006

AbstractA range of 3, 5‐disubstituted 1,3, 5‐thiadiazinane‐2‐thiones are described which decompose in moist air to give organic isothiocyanates. Organic isothiocyanates are the main biologically active catabolites from the glucosinolate components of crucifers. The thiadiazinanethiones provide a source of organic isothiocyanates for biological studies and examples of tests with pathogens and insect pests of oilseed rape are given.
Electrophysiological identification of site‐insensitive mechanisms in knockdown‐resistant strains (kdr, super‐kdr) of the housefly larva (Musca domestica)
Authors: Pepper David R. , Osborne Michael P. 
Published: November 2006

AbstractThe effects of pyrethroids were studied upon isolated segmental nerves and neuromuscular junctions in both susceptible (Cooper) and knockdown‐resistant (kdr; super‐kdr) strains of housefly larvae (Musca domestica L.). Isolated segmental nerves contained neither cell bodies nor synaptic contacts; thus, any effects of pyrethroids were attributed solely to their actions upon voltage‐dependent Na+ channels. Threshold concentrations of the type II pyrethroid, deltamethrin, required to elevate the spontaneous firing rate of these nerves were determined. Both resistant strains were about ten times less sensitive to deltamethrin than the susceptible strain, but insensitivity of super‐kdr nerves was no greater than in the less resistant kdr strain. At neuromuscular junctions, the minimum concentrations of pyrethroids needed to trigger massive increases in the frequency of miniature excitatory postsynaptic potentials (mEPSPs) were determined for deltamethrin and the type I pyrethroid, fenfluthrin. With fenfluthrin there was no detectable difference between the junctions of kdr and super‐kdr strains, which were both about ten‐fold less sensitive than Cooper junctions. With deltamethrin, kdr junctions were about 30 times less sensitive than those of Cooper; super‐kdr junctions were dramatically insensitive to deltamethrin, being some 10000‐ and 300‐fold less sensitive than those of Cooper and kdr respectively. Thus, in the synaptic assay, super‐kdr conferred an extension in resistance over kdr only against the type II pyrethroid, it being ineffective against fenfluthrin. We suggest that kdr resistance comprises at least two site‐insensitive areas within the nervous system. One involves insensitivity of the Na+ channel and has similar efficacy in both kdr and super‐kdr strains against type I and II pyrethroids; the other is associated with the presynaptic terminal and is particularly effective in super‐kdr resistance against type II pyrethroids. The latter could be associated with Ca2+‐activated phosphorylation of proteins involved with neurotransmitter release. Such phosphorylation reactions are known to be perturbed by pyrethroids, especially by type II compounds.
Effect of the acylurea insect growth regulator teflubenzuron on the endo‐larval stages of the hymenopteran parasitoids Cotesia plutellae and Diadegma semiclausum in a susceptible and an acylurea‐resistant strain of Plutella xylostella
Authors: Furlong Michael J. , Wright Denis J. 
Published: November 2006

AbstractThe toxicity of the acylurea, teflubenzuron, was assessed against larval stages of the hymenopteran parasitoids, Cotesia plutellae Kurdjumov and Diadegma semiclausum Hellén in a susceptible laboratory strain and a teflubenzuron‐resistant field strain of the diamondback moth, Plutella xylostella L. In fourth‐instar hosts (L4), when both parasitoid species were in their final larval instar, teflubenzuron significantly (P < 0.05) reduced emergence of adult D. semiclausum but had no significant (P > 0.05) effect on C. plutellae, although a small proportion of the latter were unable to reproduce. Treatment of L4 hosts with teflubenzuron ( > LD50) had no significant (P > 0.05) effect on the fecundity of surviving females of D. semiclausum. Similar differential toxicity with teflubenzuron was observed in L2 hosts, when parasitoids were at the egg or early larval instar stage. There was no apparent increased effect of teflubenzuron on either species of parasitoid when highly resistant (c. 4000‐fold) L2 hosts (field strain) were treated with concentrations of teflubenzuron two to three orders of magnitude greater than in equivalent experiments with the susceptible host strain. This suggests that host resistance to teflubenzuron confers some protection to both species of parasitoid. Uptake experiments with [14C]teflubenzuron showed that accumulation of radioactivity was much greater in D. semiclausum than in C. plutellae and this may account for the differential toxicity observed. The results are discussed in relation to the field status of these parasitoid species. The influence of insecticide resistance in the host on endo‐larval parasitoids is also considered.
The metabolism of fosetyl‐aluminium and the evolution of residue levels in oranges and tangerines
Authors: Pelegrí Rosa , Gamón Miguel , Coscollá Ramón , Beltrán Victoria , Cuñat Pascual 
Published: November 2006

AbstractThe metabolism of fosetyl‐aluminium to phosphonic acid in the peel of citrus fruit has been studied by gas chromatography using a nitrogen‐phosphorus detector and also with a flame photometric detector. At the same time the phosphonic acid residues remaining in the peel and the pulp of citrus fruit, as a result of the application of aqueous solutions of fosetyl‐aluminium at 2.5 g litre−1 to trees prior to harvest was determined.
Development of a cell‐free assay from Botrytis cinerea as a biochemical screen for sterol biosynthesis inhibitors
Authors: Stehmann Christiane , Kapteyn Johan C. , De Waard Maarten A. 
Published: November 2006

AbstractAn assay for measuring ergosterol synthesis in cell‐free extracts of the filamentous plant pathogen Botrytis cinerea is described. The extracts capable of synthesizing C4‐desmethyl sterols from [2‐ 14 C]mevalonate were derived by mechanical disruption of young conidial germlings in a Bead‐Beater apparatus. The C4‐desmethyl sterol fraction consisted of three distinct compounds and totalled 39% of the non‐saponifiable lipids formed. Ergosterol accounted for 63% of the C4‐desmethyl sterols. Only small amounts of C4‐monomethyl sterols were synthesized, while C4, 4‐dimethyl sterols made up 29% of the non‐saponifiable lipids. The latter fraction mainly consisted of lanosterol (54%) and eburicol (28%). The cell‐free system had a narrow pH optimum for synthesis of C4‐desmethyl sterols of pH 7.3–7.4. Cell‐free synthesis of C4‐desmethyl sterols was inhibited by the imidazole fungicide imazalil, concomitant with an accumulation of eburicol. The IC50 value (concentration of fungicide which inhibited cell‐free synthesis of C4‐desmethyl sterols by 50%) was 9.1 × 10 −9 M. These results are consistent with the hypothesis that imazalil is a potent inhibitor of the cytochrome P450‐dependent sterol 14x‐demethylase of B. cinerea. The method described may be used to screen compounds biochemically for inhibition of sterol synthesis in an agriculturally important plant pathogen.
Some Comments on a recently proposed method of determining chlormequat residues by derivatization with pentafluorothiophenol
Authors: Mortimer Richard D. , Weber Dorcas F. 
Published: November 2006

AbstractA recent publication concerning the analysis of residues of the herbicide chlormequat in cotton seed by gas chromatography contains a significant error. A derivative prepared by reacting pentafluorothiophenol with chlormequat is actually produced by the reaction of the initial product of demethylation of chlormequat with a second molecule of pentafluorothiophenol. As the derivative is not derived from the chlormequat backbone, the method is not specific to chlormequat and could be misleading to an analyst using it or adapting it to other produce.
Piquerol a and diacetyl piquerol act as energy transfer inhibitors of photosynthesis
Authors: Mendoza José Luis , Jiménez Manuel , Lotina‐Hennsen Blas 
Published: November 2006

AbstractATP synthesis and phosphorylating (coupled) electron flow of freshly lysed pea chloroplasts were inhibited by piquerol A and diacetyl piquerol, the latter being more active. H + ‐uptake, basal and uncoupled electron transport were not affected by either compound, indicating that they act as inhibitors of photophosphorylation at the H + ‐ATPase complex.
Termite control with microencapsulated permethrin
Authors: Schoknecht Ute , Rudolph Dieter , Hertel Horst 
Published: November 2006

AbstractBait methods with microencapsulated active ingredients are proposed for controlling local populations of subterranean termites. The foraging workers will take up the microcapsules, transport them to the nest and pass them to their nestmates.In laboratory tests microencapsulated formulations of permethrin had lethal effects on Heterotermes indicola Wasman and Reticulitermes flavipes (Kollar) depending on the amount of active ingredient applied. The time interval between the application of the capsules and the occurrence of insecticidal effects could be modified by changing the wall thickness of the capsules. Tests revealed that the microcapsules were transmitted from donors to recipients by trophallaxis. Microencapsulated formulations from which the solvent used during the manufacturing process had been removed did not reveal any repellent effects in several tests.
Plant‐growth‐regulating N‐(phosphonoacetyl)amines
Authors: Wieczorek Piotr , Miliszkiewicz Dorota , Lejczak Barbara , Soroka Miroslaw , Kafarski Pawel 
Published: November 2006

AbstractA series of N‐(phosphonacetyl)amine derivatives were synthesized and screened for plant‐growth regulating activity on Lepidium sativum L. and Cucumis sativus L. Aromatic N‐(phosphonoacetyl)amines. which may be considered as possible analogues of N‐acylaniline herbicides obtained by replacement of their acyl group by the phosphonacetyl moiety, exhibited significant or moderate herbicidal activity. In contrast, N‐(phosphonoacetyl)amino acids and N‐(phosphonoacetyl)aminophosphonic acids promoted the growth of L. sativum and C. sativus roots.
Persistence of fenthion residues in olive oil
Authors: Lentza‐Rizos Chaido , Avramides Elizabeth J. , Roberts Rosemary A. 
Published: November 2006

AbstractThe level of fenthion residues was followed for up to one year in olive oil samples. The concentration of the parent compound decreased slowly following a double‐phase first‐order decay model, both in the freezer and laboratory, while the total concentration (parent compound and its sulfoxide) remained unchanged. Storage, therefore, cannot be used as a decontamination technique for oil containing higher than the toxicologically acceptable residues of this compound.
Kinetics and hydrolysis mechanism of chlorsulfuron and metsulfuron‐methyl
Authors: Hemmamda Saadi , Calmon Michelle , Calmon Jean P. 
Published: November 2006

AbstractIn acidic media, hydrolysis of chlorsulfuron and metsulfuron‐methyl occurs via two consecutive reactions which were followed by ultraviolet spectrophotometry. For these two reactions, the pseudo‐first‐order rate constants increase proportionally to the concentration of hydronium ion in the more acidic media and to the square of this concentration at higher pH values.A kinetic study by HPLC shows that the first reaction leads to the formation of 4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐amine and (o‐chlorophenylsulfonyl) carbamic acid for chlorsulfuron or (o‐methoxycarbonylphenylsulfonyl) carbamic acid for metsulfuronmethyl. The second reaction is the conversion of these sulfonylcarbamic acids to sulfonamides and carbon dioxide. The complete lack of saccharin and of o‐sulfamoyl benzoic acid proves that the ester function of the methoxycarbonyl group is stable.The lack of general acid‐base catalysis and a solvent deuterium isotope effect less than unity are consistent with a rate‐determining cleavage of the protonated substrate.In the basic pH range (10–14) a single reaction occurs, the nucleophilic substitution of the methoxy group on the triazine by a hydroxide group.
Determination of organochlorine pesticide residues in river sediments by soxhlet extraction with hexane‐acetone
Authors: Tan Guan H. , Vijayaletchumy K. 
Published: November 2006

AbstractSoxhlet extraction with hexane + acetone (1 + 1 by volume) was used for the extraction of organochlorine pesticide residues from river sediments, followed by Florisil column chromatography clean‐up and determination by gas chromatography with an electron‐capture detector. Average recoveries exceeding 90 % were obtained using this technique. Organochlorine pesticide residue levels in sediment samples from two major rivers flowing through predominantly rice‐growing areas were determined by this method. Relatively high residue levels of organochlorine pesticides such as HCH, heptachlor and endosulfan were found in the sediments.
Interference of the phenylpyrrole fungicide fenpiclonil with membranes and membrane function
Authors: Jespers Ad B. K. , Davidse Leen C. , De Waard Maarten A. 
Published: November 2006

AbstractThe phenylpyrrole fungicide fenpiclonil accumulates to high levels in mycelium of Fusarium sulphureum and artificial liposomes. The accumulation is a result of a physicochemical distribution of the fungicide over lipid‐like material of the mycelium and the medium. Accumulation is reversible, as the fungicide can easily be removed from the mycelium by washing with water. Fenpiclonil is not metabolized by the fungus during incubation for 24 h. The fungicide affects neither membrane fluidity in artificial liposomes nor amino acid accumulation in bacterial vesicles. Thus, accumulation of the fungicide does not seem to affect the functioning of membranes.Fenpiclonil induces the accumulation of the membrane‐potential probe tetra‐phenylphosphonium bromide by F. sulphureum. Since accumulation of this probe probably reflects the cumulative potential over all cell membranes, the increased accumulation is more likely a result of changes of potentials over membranes of intracellular organelles rather than plasma membrane hyperpolarization. Hence, the previously described effects of fenpiclonil on amino acid and saccharide uptake cannot be explained by plasma membrane hyperpolarization.
Characterisation of benzimidazole‐resistant strains of Rhynchosporium secalis
Authors: Kendall Sheila , Hollomon Derek W. , Ishii Hideo , Heaney Steven P. 
Published: November 2006

AbstractAbstract: Benzimidazole‐resistant mutants of Rhynchosporium secalis were easily generated in the laboratory using UV mutagenesis. Three levels of resistance were identified (low, LR; moderate, MR; high, HR), but there was no negative cross‐resistance with N‐phenylcarbamate fungicides. In all cases pathogenicity was reduced, in some cases drastically. Benzimidazole‐resistant field strains were first detected in 1990, some 15 years after this fungicide group was first used in UK barley crops. Unlike laboratory mutants, only HR phenotypes were isolated from the field, and all showed negative cross‐resistance to N‐phenylcarbamates. These field resistant strains were no less pathogenic than wild‐type ones. Carbendazim binding to tubulin‐like protein from HR phenotypes, whether generated in the laboratory or isolated from the field, was reduced.
Responses of phosphine‐resistant strains of two stored‐product insect pests to changing concentrations of phosphine
Authors: Rajendran Somiahnadar 
Published: November 2006

AbstractAbstract: The susceptibility of eggs, pupae and adults of Tribolium castaneum (Herbst) and adults of Rhyzopertha dominica (F.), (both phosphine‐resistant strains) to phosphine at fixed concentration‐time (ct) products, with either constant or increasing or decreasing concentrations was studied at 25 (± 1)°C. At lower ct products, falling concentrations of phosphine generally caused reduced insect mortality in all the three exposure periods in the range 12 to 72 h. However, in R. dominica, both increasing and decreasing concentrations were less effective than constant concentrations. At higher ct products, no significant change in the mortality response was observed in either species after exposure to constant or changing concentrations. The findings indicate the need to maintain sufficiently high concentrations of phosphine until the end of the fumigation period.
Response of maize (Zea mays) inbreds and hybrids to rimsulfuron
Authors: Green Jerry M. , Ulrich Jim F. 
Published: November 2006

AbstractAbstract: Extensive glasshouse studies characterized the varietal response to rimsulfuron of 37 inbreds of maize (Zea mays L.), representing the major inbred families used in hybrid seed production, and 20 defined hybrids from these inbreds. Tolerant hybrids were produced when one or both of its parents were tolerant. Sensitive hybrids occurred only when both parents were sensitive. Genetic analysis indicated that sensitivity is controlled by a single recessive gene. Dose‐response analysis showed varieties could vary more than 40000‐fold in sensitivity. Only the AHAS‐modified variety with the XA‐17 gene had changed enzyme sensitivity. This gene provided crop tolerance to very high rates of rimsulfuron and its interaction with an organophosphate insecticide. Breeders can eliminate varietal sensitivity in three ways: always use at least one tolerant hybrid parent, backcross sensitive inbreds with tolerant, or use an AHAS‐modified gene.
Study of dimethoate bioaccumulation in liver and muscle tissues of Clarias batrachus and its elimination following cessation of exposure
Authors: Begum Ghousia , Vijayaraghavan Shanta , Sarma P. Nageswara , Husain Sajid 
Published: November 2006

AbstractAbstract: Dimethoate accumulation in liver and muscle tissues of a fresh‐water fish, Clarias bactrachus L., was measured by gas liquid chromatography. Fish were exposed to a sub‐lethal concentration of the pesticide in the laboratory water tank for a period of eight days. The accumulation increased up to two days, followed by decrease on the 4th and 8th days of exposure in both liver and muscle tissues. Maximum accumulation was found in liver. After eight days of exposure, fish were released into pesticide‐free water to study the rate of loss of the pesticide. It was found that liver and muscle tissues were cleared of dimethoate after four and eight days respectively.
Distribution of glyphosate and of its target enzyme inside wheat plants
Authors: Arnaud Laurence , Nurit Françoise , Ravanel Patrick , Tissut Michel 
Published: November 2006

AbstractEnolpyruvylshikimate phosphate (EPSP) synthase activity has been measured in different organs of 1–14‐day‐old wheat seedlings growing in culture chambers. Enzyme activity was first detected after two days, and reached its maximum value at day 4. It remained almost unchanged for 14 days thereafter. During germination, one of the most important sources of enzyme was the seed scutellum. Later, the developed leaves contained 43% of the whole stock of enzyme. Although the enzyme distribution was not identical under light or in the dark, there was no evident light induction of EPSP synthase. High enzyme activity was found in the coleoptile, continuing for the whole life‐time of this organ, and which might be associated with its lignification. Five to 40% of the total enzyme was found in the roots, reaching a maximum at 14 days. At this stage, glyphosate applied to the first grown leaf was phloem‐transported to the sink organs, with no clear relationship being shown between EPSP synthase activity and herbicide quantity in each organ. At day 4, glyphosate treatment, by soaking the seedlings in the herbicide solution, was followed by an active phloem transport from the scutellum to the growing parts. The average internal concentration of radiolabelled compounds (glyphosate plus its possible derivatives) which induced wheat seedling growth decrease, was shown to reach 50 to 100 μM under our conditions.