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MgMfs1, a major facilitator superfamily transporter from the fungal wheat pathogen Mycosphaerella graminicola, is a strong protectant against natural toxic compounds and fungicides.

MgMfs1, a major facilitator superfamily (MFS) gene from the wheat pathogenic fungus Mycosphaerella graminicola, was identified in expressed sequence tag (EST) libraries. The encoded protein has high homology to members of the drug:H(+) antiporter efflux family of MFS transporters with 14 predicted transmembrane spanners (DHA14), implicated in mycotoxin secretion and multidrug resistance. Heterologous expression of MgMfs1 in a hypersensitive Saccharomyces cerevisiae strain resulted in a strong decrease in sensitivity of this organism to a broad range of unrelated synthetic and natural toxic compounds. The sensitivity of MgMfs1 disruption mutants of M. graminicola to most of these compounds was similar when compared to the wild-type but the sensitivity to strobilurin fungicides and the mycotoxin cercosporin was increased. Virulence of the disruption mutants on wheat seedlings was not affected. The results indicate that MgMfs1 is a true multidrug transporter that can function as a determinant of pathogen sensitivity and resistance to fungal toxins and fungicides.

Antifungal Agents↗

Agonistic effect of imidazole and triazole fungicides on in vitro oocyte maturation in rainbow trout (Oncorhynchus mykiss).

The purpose of the present study was to assess the in vitro effect of some imidazole (prochloraz, imazalil) and triazole (epoxiconazole) agricultural fungicides on gonadotropin-induced oocyte maturation in rainbow trout. Results show that prochloraz, epoxiconazole and imazalil strongly potentiated the induction of oocyte maturation by gonadotropin in a dose-dependent manner. Furthermore, 10(-5) M prochloraz and epoxiconazole alone induced oocyte maturation. The mRNA biosynthesis inhibitor, actinomycin d, completely inhibited oocyte maturation induced by fungicides, suggesting that the gonadotropin-like effect of these chemicals is at least dependent on de novo gene expression.

Animals↗

Influence of copper fungicide residues on occurrence of earthworms in avocado orchard soils.

The compost worm Eisenia fetida was used to demonstrate the avoidance by worms of Cu contaminated soil. Soils were collected from two avocado orchards in north eastern New South Wales, Australia. In avoidance trials, worms preferred non-contaminated control soils, sourced from adjacent to the orchard or an OECD control soil, when Cu residues in the orchard soils reached 4-34 mg Cu kg(-1). At levels of 553 mg Cu kg(-1), 90% avoidance of orchard soil was observed. The worms showed preference for the soils in the order; uncontaminated field derived soil >OECD standard soil >Cu contaminated orchard soil. It was demonstrated that OECD standard soil was less favoured by worms than control soil derived from the test sites. While Cu was found to be the primary influence on worm avoidance in orchard soil, other factors, such as elevated soil Zn concentrations, could not be discounted. In a corresponding field study, it was shown that earthworms occurred at lower density in orchard soils with a history of Cu fungicide use. In one such orchard, soil Cu concentrations of up to 270 mg kg(-1) were determined and no earthworms were found, while nearby control sites and less contaminated sites within the orchard had up to 40.7 g m(-2) earthworm biomass. Considering the potential for Cu to accumulate in these soils and the subsequent impacts on soil biota, our results highlight the importance of limiting future application of Cu based fungicides.

Agriculture↗

Fungicidal value of wood tar from pyrolysis of treated wood.

The objective of the paper was to estimate the fungicidal value of wood tar extracted as a product of pyrolysis of wood previously treated with either creosote oil or CCB-type salt preservative. The effectiveness of wood treated with one of these two wood tar residuals was compared to the effectiveness of wood treated with virgin creosote oil (type WEI-B) and an untreated control. Wood was impregnated with alcohol solutions of the two extracted preservatives or virgin creosote oil and then subjected to the Coniophora puteana, Poria placenta and Coriolus versicolor fungi. The fungicidal values of the investigated preservatives were determined with the use of the short agar-block method and the aging test according to the standard EN 84. It was found that wood tar extracted by pyrolysis of old creosote-treated wood and then used to treat wood may have potential as a preservative for wood protection or as a component of preservatives.

Basidiomycota↗

Mitochondrial electron transfer in the wheat pathogenic fungus Septoria tritici: on the role of alternative respiratory enzymes in fungicide resistance.

Certain phytopathogenic fungi are able to express alternative NADH- and quinol-oxidising enzymes that are insensitive to inhibitors of the mitochondrial respiratory Complexes I and III. To assess the extent to which such enzymes confer tolerance to respiration-targeted fungicides, an understanding of mitochondrial electron transfer in these species is required. An isolation procedure has been developed which results in intact, active and coupled mitochondria from the wheat pathogen Septoria tritici, as evidenced by morphological and kinetic data. Exogenous NADH, succinate and malate/glutamate are readily oxidised, the latter activity being only partly (approx. 70%) sensitive to rotenone. Of particular importance was the finding that azoxystrobin (a strobilurin fungicide) potently inhibits fungal respiration at the level of Complex III. In some S. tritici strains investigated, a small but significant part of the respiratory activity (approx. 10%) is insensitive to antimycin A and azoxystrobin. Such resistant activity is sensitive to octyl gallate, a specific inhibitor of the plant alternative oxidase. This enzyme, however, could not be detected immunologically. On the basis of the above findings, a conceptual mitochondrial electron transfer chain is presented. Data are discussed in terms of developmental and environmental regulation of the composition of this chain.

Acrylates↗

Multiresidue method for the rapid determination--in grape, must and wine--of fungicides frequently used on vineyards.

A rapid multiresidue gas chromatographic method for determining 17 fungicides in grapes, must and wine, widely used on vineyards, is described. A simple on-line microextraction method for isolation of fungicides was used. Nitrogen-phosphorus and electron-capture detection were used for the identification and quantitation of pesticides. For confirmation, mass spectrometic detection was used. Because of the high selectivity of both detection methods, no clean-up was necessary. The regression coefficients relating to linearity were at least 0.994. Recoveries from spiked grapes, must and wine samples ranged from 78 to 107% and relative standard deviations were not higher than 14%. Individual detection limits were in the range 0.02-0.1 ng. Limits of quantification varied from 0.01 to 0.05 mg/kg, smaller in all cases than the maximum residue limits set down by the legislations of Spain, France and Italy, the main wine-producing countries of the European Union. Only for fludioxonil and hexaconazole do the limits of quantification coincide with the maximum residue limits (0.05 mg/kg) established by the Spanish legislation.

Chromatography, Gas↗

Chromatographic analysis of fungicides.

The separation and analysis of a wide range of fungicides, by gas, liquid, column, paper, and thin-layer chromatography have been reviewed. Major attention has been given to methods for the identification and quantitation of individual and multiresidues of fungicides in environmental and agricultural samples.

Chromatography↗

Liquid chromatographic-mass spectrometric determination of post-harvest fungicides in citrus fruits.

Liquid chromatography (LC)-atmospheric pressure ionisation (API)-mass spectrometry (MS) has been used to determine residues of five fungicides in oranges with a minimum sample cleanup. Atmospheric pressure chemical ionisation (APCI) and electrospray (ES) were compared and both gave similar results in terms of sensitivity and structural information. The main ions were [M+H]+ for carbendazim, imazalil, thiophanate methyl and thiabendazole, and [M+H-C4H9NHCO]+ for benomyl. Samples were extracted with sodium sulphate and ethyl acetate. Although benomyl and thiophanate methyl were transformed through the extraction procedure to carbendazim, the method showed good precision (<13%) and recovery (>70%), except for thiophanate methyl (50%), whilst also yielding limits of detection (<0.03 mg kg(-1)) that are adequate for the determination of the studied fungicides in oranges.

Atmospheric Pressure↗

Analysis of post-harvest fungicides by micellar electrokinetic chromatography.

A method based on solid-phase extraction (SPE) and micellar electrokinetic chromatography (MEKC) was developed for the simultaneous determination of carbendazim, imazalil, methylthiophanate, O-phenylphenol, prochloraz, procimidone, thiabendazole and triadimefon residues in grape, lettuce, orange and tomato. Selectivity and resolution were studied changing the pH and the concentration of the buffer, the type and concentration of surfactant and the methanol content in the mobile phase. A buffer consisting of 4 mM borate with 75 mM sodium cholate (pH 9.2) gave the best results. The recoveries of the fungicides in spiked fruit and vegetable samples ranged from 30 to 105%, and the limits of detection were between 0.1 and 1 mg kg(-1). The reproducibility and repeatability of the combination of SPE pretreatment and MEKC were good for all the compounds, except for imazalil and O-phenylphenol in oranges, due to some matrix compounds interfering with the separation. The method was applied to post harvest treated samples, and the fungicides were sometimes detected at concentration levels lower than maximum residue limits (MRLs).

Buffers↗

Stir bar sorptive extraction applied to the determination of dicarboximide fungicides in wine.

The dicarboximide fungicides vinclozolin, iprodione and procymidone were analyzed in white wines using stir bar sorptive extraction (SBSE) in combination with thermal desorption-capillary GC-MS analysis (TD-cGC-MS). The method was optimized using spiked water samples in a concentration range between 0.5 and 100 microg/l. Iprodione was measured as its degradation product 3,5-dichlorophenyl hydantoin. Limits of quantification in the full scan MS mode are 0.5 microg/l for vinclozolin and procymidone and 5 microg/l for iprodione. In the ion monitoring mode, concentrations 100 times lower can be dosed. Because of wine matrix effects on the recoveries, quantification of the target fungicides in wine had to be carried out by standard addition. For the thermolabile iprodione, the accuracy of SBSE-TD-cGC-MS was verified using SBSE followed by liquid desorption and analysis by liquid chromatography-atmospheric pressure chemical ionization mass spectroscopy. Procymidone and iprodione were detected in wines in concentrations up to 65 microg/l while the highest concentration of vinclozolin detected was smaller than 3 microg/l.

Aminoimidazole Carboxamide↗

Application of matrix solid-phase dispersion to the determination of a new generation of fungicides in fruits and vegetables.

A method based on matrix solid-phase dispersion (MSPD) and gas chromatography to determine eight fungicides in fruits and vegetables is described. Fungicide residues were identified and quantified using nitrogen-phosphorus detection and electron-capture detection connected in parallel and confirmed by mass spectrometric detection. The method required 0.5 g of sample, C18 bonded silica as dispersant sorbent, silica as clean-up sorbent and ethyl acetate as eluting solvent. Recoveries from spiked orange, apple, tomato, artichoke, carrot and courgette samples ranged from 62 to 102% and relative standard deviations were less than 15% in the concentration range 0.05-10 mg kg(-1). Detection and quantitation limits ranged 3-30 microg kg(-1) and 10-100 microg kg(-1), respectively, with linear calibration curves up to 10 mg kg(-1). The analytical characteristics of MSPD compared very favourably with the results of a classical multiresidue method, which uses ethyl acetate and anhydrous sodium sulphate for the extraction.

Chromatography, Gas↗

Application of porous carbon for solid-phase extraction of dicarboxyimide fungicide residues from wines in combination with high-resolution capillary gas chromatography and gas chromatography-mass spectrometry.

Solid-phase extraction with a novel porous carbon sorbent CARB GR was used for the clean-up step of dicarboxyimide fungicides residues from variety of Slovak grape wines with subsequent capillary gas chromatography-flame ionization detection, -electron-capture detection (ECD) and -mass spectrometry-ion-trap detection (MS-ITD) analysis. Recovery was tested at various concentration levels of vinclozolin and iprodione in standard solutions (R = 80-97%, R.S.D. < or = 5). The value of recovery in spiked wines is dependent on concentration level (studied in the range of 5.9 micrograms/1-1.96 mg/l) and on the variety of wine (R = 80-96%; R.S.D. = 3-5%). Limits of quantitation (for sample volume 50 ml) were determined to be with GC-ECD for both fungicides in ppt range and with GC-MS-ITD in the multiple ion detection mode monitoring in ptt range for vinclozolin and ppb range for iprodione. Concentration levels of vinclozolin residues were determined in treated wines (with 0.1% Ronilan 50 WP) as well as iprodione residues (with 0.15% Rovral 50 WP) and a strong dependence on the protective term before the harvest is shown.

Aminoimidazole Carboxamide↗

Fate of the fungicide dodemorph during anaerobic digestion of biological waste.

The aim of this study was to examine the stability and distribution of the fungicide dodemorph during anaerobic digestion of biological waste, including a short subsequent aerobic treatment. Three reactor experiments were conducted. The influences of pH and dissolved organic carbon (DOC) were further studied in batch experiments. The reactor experiments showed no decrease in the concentration of dodemorph, indicating stability of the fungicide. In connection with the results of the batch experiments, a clear pH-dependency of the partitioning of dodemorph between solid and water phase could be shown. At pH values below the pK(a) value of 7.8, protonated dodemorph molecules predominate. However, a release into the water phase was only observed at pH values of 5 and below. It can be assumed that in the pH range between 5 and 7.8 dodemorph forms bonds with carboxyl groups of organic matter. Dodemorph was not completely extractable from the solid waste matrix due to strong bonds with the organic matter. Solubilising effects by water ingredients of the process water were not apparent.

Anaerobiosis↗

Initiation and promotion of altered hepatic foci in female rats and inhibition of cell-cell communication by the imidazole fungicide prochloraz.

The imidazole fungicide prochloraz (1-[N-propyl-N-2-(2,4,6-trichlorophenoxy) ethyl carbamoyl] imidazole) was investigated for its ability to inhibit gap junctional intercellular communication in the scrape-loading/dye-transfer assay in IAR 20 rat liver epithelial cells and for effects on the initiation and promotion stages of hepatocarcinogenesis. Female Sprague-Dawley rats initiated with N-nitrosodiethylamine 24-hr after partial hepatectomy were administered prochloraz five days a week by oral gavage (30 or 150 mg/kg) for 10 weeks. Altered hepatic foci (AHF) were analyzed by quantitative stereology from liver sections stained for gamma-glutamyltranspeptidase (GGT) and glutathione S-transferase P (GST-P). The fungicide was also studied for its ability to initiate the development of GGT-positive AHF in rat liver. The in vitro studies showed prochloraz to be an inhibitor of cell-cell communication in the test system used. In the in vivo studies, prochloraz showed no effect on the initiation of GGT-positive foci. However, significant increases in the percentage of liver tissue occupied by GGT-positive AHF and the number of GST-P-positive AHF per cm3 in initiated animals were recorded in the low dose group. The present data suggest that prochloraz acts as a weak tumour promoter of hepatocarcinogenesis but does not initiate this process.

Animals↗

Determination of presence of fungicides by their common metabolite, 3,5-DCA, in compost.

This paper describes the determination of 3,5-DCA in commercial composts, a common metabolite in a class of fungicides, and dicarboximides (Vinclozolin, Chlozolinate, Iprodione, Procymidone) which are commonly used in agriculture. The extracts, obtained in acetonitrile by sonication, are analysed by HPLC/DAD without clean-up. This method has shown several advantages: reduced manipulation of samples, good recovery (80-90%) and good reproducibility (RSD% <7). The limit of detection (DL) of the analytical method has been estimated as 15 microg/kg for the common metabolite, and 35-145 microg/kg for the four fungicides in the matrices.

Agrochemicals↗

Determination and identification of metabolites of the fungicides Iprodione and Procymidone in compost.

The main metabolites formed from Iprodione and Procymidone during the composting process have been isolated and identified by HPLC-DAD-MSD. After addition of the fungicides to the composting pile, we monitored the reaction of the two analytes and the formation of their degradation products for eight months. We verified the nature of the metabolites by comparison with those hypothesised in the literature and by comparison with the behaviour of an abiotic process in aqueous acetonitrile pH 6 and at 35 degrees C. After taking into account the different kinetic behaviours of the fungicides on degradation in compost and hydro-organic solution, breakdown pathways are proposed for biodegradation.

Aminoimidazole Carboxamide↗

Linking lysosomal biomarker and population responses in a field population of Aporrectodea caliginosa (Oligochaeta) exposed to the fungicide copper oxychloride.

The effects of the fungicide copper oxychloride on a field population of the earthworm Aporrectodea caliginosa were investigated. Changes were monitored in earthworm numbers and biomass, copper concentrations in soil and earthworms, and neutral red retention times (NRRTs) of coelomocytes. The aim was to establish whether the cellular responses could be linked to changes at the population level. Results indicated that there was a significant (P<0.05) impact on worm density and biomass on the treated plots 6 months after spraying with the fungicide stopped. NRRTs of treated earthworms were significantly lower after one spraying when earthworms had elevated concentrations of copper in their body tissues. Six months after spraying stopped, copper levels in both soil and earthworm tissues declined significantly, but the earthworm numbers and biomass were still significantly lower in the treated plots. This indicated that the effects of the copper oxychloride exposure manifested at a much later stage at the population level, than on NRRT. We conclude that the decrease in NRRTs, which preceded the decrease in both earthworm biomass and numbers, may have predictive value as a biomarker of impending population changes.

Animals↗

Cytochrome P450 enzymes in the kidney of the bobwhite quail (Colinus virginianus): induction and inhibition by ergosterol biosynthesis inhibiting fungicides.

Metabolism of testosterone and the alkoxyresorufins was examined in kidney microsomes from male Bobwhite quail (Colinus virginianus) and was compared with that in kidney microsomes prepared from the male rat. In addition, cross-reactivity studies were conducted with a number of antibodies prepared against cytochrome P450 (CYP) enzymes purified from rat and trout liver. The effects of treatment with the fungicides: propiconazole, vinclozolin, clotrimazole and ketoconazole were examined. While kidney microsomes from both quail and rat catalyzed testosterone metabolism at multiple positions, the pattern of hydroxylated metabolites differed. Treatment with vinclozolin resulted in significant induction of testosterone 2 beta- and 15 beta-hydroxylase activity in quail kidney accompanied by increases in expression of P450 enzymes cross-reactive with antibodies raised against a CYP 3A-like protein in teleost fish. In contrast, ketoconazole treatment resulted in inhibition of testosterone hydroxylation at positions 15 beta- and 6 alpha-. Propiconazole and vinclozolin significantly induced a CYP 1A1 cross-reactive P450 enzyme in quail kidney 2-3-fold unaccompanied by significant increases in alkoxyresorufin O-dealkylase activity. These activities were significantly inhibited by ketoconazole treatment. Quail kidney microsomes also expressed high levels of a CYP 4A1 cross-reactive apoprotein which was inducible 3-4-fold by ketoconazole. Thus, quail kidney possesses cytochrome P450 enzymes related to forms found in mammalian gene families 1, 3 and 4. Fungicide treatment results in mixed patterns of induction and inhibition of kidney P450 enzymes different from those previously reported in quail liver.

Animals↗