摘要:

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 IC50value (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

ISSN:0031-613X    

DOI:10.1002/ps.2780400102

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe sterol 14α‐demethylation inhibitors 1‐(4‐substituted phenoxymethyl)‐2, 2‐dimethylpropyl imidazole‐1‐carboxylates and their corresponding thiocarboxylates were optimized for maximum in‐vitro activity against Botrytis cinerea Pers. ex Fr. in terms of the lipophilic parameter π. The activity of both carboxylates and thiocarboxylates was strongly related with π and predicted to be maximum at π 1.38 and 0.72 respectively. However, the preventive efficacy of the carboxylates against B. cinerea on Solanum melongena L. grown in a greenhouse did not correlate with the parameter. Despite the unfavourable lower lipophilicity, compounds with p‐alkoxy substituents were superior to those with any other substituent. Moreover, the p‐methoxy‐substituted thiocarboxylate 46 was much less effective in greenhouse tests than the corresponding carboxylate 15, despite their equivalent in‐vitro activity. To clarify these discrepancies, hydrolytic and photolytic stabilities of several representative compounds including 15 and 46 were investigated. The carboxylates examined were much more labile to hydrolysis than the thiocarboxylate 46; however, the four thiocarboxylates studied were less stable to light than the carboxylates. Consequently, the above discrepancies were attributable mainly to the superior stability of the carboxylates to photolysis as compa

ISSN:0031-613X    

DOI:10.1002/ps.2780400103

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractVarious agricultural spray adjuvants are available which are classified as anti‐evaporants. This quality has the potential to aid in reducing drift and chemical evaporation and so improving coverage. Numerous other adjuvants not claiming these benefits may have these characteristics which are not being exploited. In order to assess these qualities, a simple, rapid assay was devised for measuring relative evaporation rates from individual drops. This method was then used to measure the evaporation rates of a variety of adjuvants under controlled temperature and humidity conditions.The droplet producing device uses a microliter syringe to dispense a droplet of known size. After a given period of time, the drop is taken back into the syringe and the volume lost to evaporation calculated. Modifications to the original device include suspending the drop inside a temperature‐ and humidity‐controlled chamber.The original device was used for determining the rate of evaporation from water drops later than 0.3 mm. We have extended the use of the device to measure the rates of evaporation from a range of adjuvant solutions under controlled temperature and humidity conditions. The data reported here suggest that this method (a) is suitable for measuring evaporation from drops of many (but not all) adjuvant formulations, (b) is capable of discerning differences in relative rates of evaporation and (c) may be used for an array of adjuvant, drop size, and meteorological conditions. Major limitations appear to be (1) equilibrium surface tension, solutions having values less than c.35 mN m −1 are difficult to analyze and (2) a lower limit on drop‐size of

ISSN:0031-613X    

DOI:10.1002/ps.2780400104

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract4‐chloroaniline was oxidized by soya cell‐wall peroxidases in the presence of hydrogen peroxide. The main product, an orange compound with a maximal absorbance at 455 nm, was probably 4, 4′‐dichloroazobenzene. The optimum pH of the reaction was 4. Michaelis constants, determined as described by Dalziel, were 21 mM for 4‐chloroaniline and 94 μM for hydrogen peroxide. Syringaldazine was an uncompetitive inhibitor of 4‐chloroaniline peroxidation (Ki=46 μM) and modified the progress of the reaction with the appearance of a lag period. By contrast, 4‐chloroaniline was a non‐competitive inhibitor of syringaldazine peroxidation with a Kivalue of 21 mMxat pH 7.5. Therefore, these two inhibiting effects were compatible with the presence of two binding sites for two different hydrogen donors. Both sites were linked by allosteric interactions. The inferences on chloroaniline bind

ISSN:0031-613X    

DOI:10.1002/ps.2780400105

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

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.

ISSN:0031-613X    

DOI:10.1002/ps.2780400106

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

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 comp

ISSN:0031-613X    

DOI:10.1002/ps.2780400107

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractAn improved method for the quantitative analysis of the herbicide glyphosate [N‐(phosphonomethyl)glycine] in soils containing moderate to high clay content is described. Critical evaluations of previously published methods have indicated that recoveries of glyphosate from soils with high clay content are often low. Where acceptable recovery estimates have been reported, these methods also report increased interferences and rarely include soils with clay content exceeding 30%.The proposed method was developed and characterized using six soils of different clay content (25–87% clay), with other physical and chemical properties as described. Recoveries of glyphosate from the soils were determined after duplicate extractions with 0.1 M potassium hydroxide. Clean‐up of soil extract solutions was by cation‐exchange column chromatography. Subsequent quantitation was by HPLC with post‐column oxidation, followed by derivatization using OPA‐MERC with fluorometric detection. No interferences were detected.Recovery estimates for each fortified sample were determined over a concentration range (0.56–11.25 mg glyphosate kg −1 ) with all recoveries being greater than 80%. Detection limit for glyphosate in soil was 0.04 mg kg −1, and instrument response was linear for solutions up to 50.0μg glyphosate ml −1. Reproducibility relative confidence interval, for a single sample analysi

ISSN:0031-613X    

DOI:10.1002/ps.2780400108

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

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.

ISSN:0031-613X    

DOI:10.1002/ps.2780400109

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

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. sa

ISSN:0031-613X    

DOI:10.1002/ps.2780400110

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

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 compo

ISSN:0031-613X    

DOI:10.1002/ps.2780400111

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY