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At least 613 records · Page 34Linked to original sources
PubMed1971

Influence of fungicides and irrigation practice on aflatoxin in peantus before digging.

Peanuts grown under dryland conditions where drought stress occurred accumulated more aflatoxin before digging than peanuts grown under irrigation. Kernels became more susceptible to Aspergillus flavus and A. parasiticus invasion when the soil moisture in the pod zone approached levels at which moisture moved from the pod into the soil and the kernel moisture dropped below 31%. Isolation frequencies of these aspergilli from fresh-dug kernels were lowest in 1968 (maximum of 3%). In 1967 and 1969, maximum percentages of 100 and 74, respectively, were noted. Kernel infestation was correlated with degree of aflatoxin contamination. Dryland fresh-dug kernels contained a maximum of 35,800 parts per billion aflatoxin while a maximum of 50 parts per billion was detected in kernels from irrigated plots. In 1969 A. flavus infestation was as high as 59% in peanuts from irrigated plots; however, no aflatoxin was detected. Absence of aflatoxin in these samples is attributed to the higher kernel moisture content which reduced the aflatoxin-producing potential of A. flavus. Statistical analysis of the data revealed no significant differences in degree of fungal infestation, production levels, and grade factors between any fungicide treatments.

Acetone↗
PubMed1972

Mode of action of oxathiin systemic fungicides. V. Effect on electron transport system of Ustilago maydis and Saccharomyces cerevisiae.

The systemic fungicide carboxin (5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilide) at 100 mum inhibited succinate cytochrome c reductase in mitochondria from Ustilago maydis and Saccharomyces cerevisiae. It did not have any effect on reduced nicotinamide adenine dinucleotide (NADH) cytochrome c reductase. Succinate coenzyme Q reductase was also inhibited, but NADH coenzyme Q reductase was not. When dichlorophenolindophenol (DCIP) was used as the terminal acceptor of electrons from the oxidation of succinate, carboxin was very effective in inhibiting succinate-DCIP reductase. Carboxin was inhibitory to succinic dehydrogenase assayed with phenazine methosulfate plus DCIP when intact mitochondria were used as the enzyme source but not when solubilized enzyme was used. The main site of action of carboxin, therefore, appears to lie between succinate and coenzyme Q. The dioxide analogue of carboxin was also effective in inhibiting succinate-cytochrome c reductase, succinate-coenzyme Q reductase, or succinate-DCIP reductase, whereas the monoxide analogue was less effective in inhibiting these enzymes.

Anilides↗
PubMed2003

Urine mutagenicity and lymphocyte DNA damage in fruit growers occupationally exposed to the fungicide captan.

AIMS: To determine haematological parameters, urine mutagenicity (on three Salmonella typhimurium strains), and DNA damage (using the comet assay) in mononuclear leucocytes of farmers before and after a one-day spraying period of pear and apple trees with the fungicide captan in usual conditions. METHODS: Fruit growers were exposed to captan during the 1998 (n = 12) and/or the 2000 spraying seasons (n = 17). Biological samples were collected on the morning of the day of spraying (S1), the evening after spraying (S2), and the morning of the day after (S3). The UK Predictive Operator Exposure Model (UK-POEM) was used to quantify pesticide exposure intensity. RESULTS: No effect was observed on haematological parameters for these two spraying seasons. Proportions of mutagenic urine samples did not significantly differ between S1 and S2/S3 sampling points. In contrast with strains TA97a and YG1041 mainly sensitive to frameshift mutations, a positive trend was observed between the difference (S3-S1) of mutagenic power on strain TA102 detecting base-pair mutations and the exposure predicted value given by UK-POEM, mainly due to parameters related to protective clothing. No significant variations in DNA damage levels were observed between S1 and S3, nor were correlations observed with parameters of pesticide exposure. CONCLUSIONS: A one-day spraying period with captan and other pesticides does not significantly induce DNA damages in mononuclear leucocytes. In contrast, an inefficient protective clothing could correlate with an increase in urine mutagenicity as assessed by the TA102 tester strain.

Adult↗
PubMed1992

Occupational asthma induced by the fungicide tetrachloroisophthalonitrile.

A 48 year old male farmer had recurrent episodes of dyspnoea, shortness of breath, and wheezing after being in his plastic greenhouse when the fungicide tetrachloroisophthalonitrile had been sprayed. A bronchial provocation test with a control challenge and a patch skin test confirmed that his asthma was induced by tetrachloroisophthalonitrile.

Agricultural Workers' Diseases↗
PubMed1978

Effect of fungicide Folpet on growth and chromosomes of human lymphoid cell lines.

One normal human lymphoid cell line was treated continuously with the fungicide Folpet (N-trichloromethylthio-phthalimide) at 0.5, 1, 2, and 4 microgram/ml of media and one Burkitt cell line was pulse-treated with the same compound for 15 min at 2.5, 5, 10, and 15 microgram/ml. Various times after treatment, cell viability counts and chromosomes analyses were made. Severe cell growth inhibition and an increase in chromosome aberrations were observed in both cell lines. There were two types of induced chromosome aberrations. Aberrations type A appeared in cultures treated with lower doses and were characterized by chromosome or chromatid gaps and breaks and also infrequently seen exchanges and dicentrics. In the later stages of the experiment, the rate of growth and aberrations returned to control levels. Chromosome aberrations type B appeared in early samples of cultures treated with higher doses. The whole complement of chromosomes was affected. The aberrations included chromosome stickiness, despiralization and pulverization. The cultures died off within two days.

Cell Division↗
PubMed1987

Inhibition of yeast respiration and fermentation by benomyl, carbendazim, isocyanates, and other fungicidal chemicals.

The inhibition of yeast (Saccharomyces cerevesiae) metabolism by fungicidal chemicals was investigated. Glucose- or ethanol-dependent yeast respiration was measured with an oxygen electrode, and manometric determination of carbon dioxide release was used to measure fermentation. Both respiration and fermentation were inhibited more by benomyl than by identical molar concentrations of its breakdown product, carbendazim. Butyl isocyanate, another benomyl breakdown product, inhibited respiration more but inhibited fermentation less than the parent compound. Of the isocyanates tested, hexyl isocyanate was the most inhibitory towards both activities. Captan was more active and iprodione less active than benomyl. Because benomyl rapidly broke down to carbendazim when it was prepared in 80% ethanol, only 59% of the dissolved benomyl was intact when it was added to yeast to determine its effect on respiration or fermentation.

Benomyl↗
PubMedDate not supplied

Peripubertal exposure to the antiandrogenic fungicide, vinclozolin, delays puberty, inhibits the development of androgen-dependent tissues, and alters androgen receptor function in the male rat.

Vinclozolin is a well-characterized antiandrogenic fungicide. It produces adverse effects when administered during sexual differentiation, and it alters reproductive function in adult male rats by acting as an androgen-antagonist. Two active metabolites of vinclozolin, M1 and M2, compete with natural androgens for the rat and human androgen receptors (ARs), an effect that blocks androgen-induced gene expression in vivo and in vitro. In addition to their effects during perinatal life, androgens play a key role in pubertal maturation in young males. In this regard, the present study was designed to examine the effects of peripubertal oral administration of vinclozolin (0, 10, 30, or 100 mg kg-1 day-1) on morphological landmarks of puberty, hormone levels, and sex accessory gland development in male rats. In addition, as binding of the M1 and M2 to AR alter the subcellular distribution of AR by inhibiting AR-DNA binding, we examined the effects of vinclozolin on AR distribution in the target cells after in vivo treatment. We also examined serum levels of vinclozolin, M1, and M2 in the treated males so that these could be related to the effects on the reproductive tract and AR distribution. Vinclozolin treatment delayed pubertal maturation (at 30 and 100 mg kg-1 day-1) and retarded sex accessory gland and epididymal growth. Serum luteinizing hormone (LH; significant at all dosage levels) and testosterone and 5 alpha-androstane, 3 alpha, 17 beta-diol (at 100 mg kg-1 day-1) levels were increased. Testis size and sperm production, however, were unaffected. It was apparent that these effects were concurrent with subtle alterations in the subcellular distribution of AR. In control animals, most AR were in the high salt cell fraction, apparently bound to the natural ligand and DNA. Vinclozolin treatment reduced the amount of AR in the high salt (bound to DNA) fraction and it increased AR levels in the low salt (inactive, not bound to DNA) fraction. M1 and M2 were found in the serum of animals from the two highest dosage groups, but they were present at levels well below their K1 values. In summary, these results suggest that when the vinclozolin metabolites occupy a small percentage of AR in the cell, this prevents maximal AR-DNA binding and alters in vivo androgen-dependent gene expression and protein synthesis, which in turn results in obvious alterations of morphological development and serum hormone levels. It is noteworthy that similar exposures during prenatal life result in a high incidence of malformations in male rats.

Administration, Oral↗
PubMed2006

Embryonic exposure to the fungicide vinclozolin causes virilization of females and alteration of progesterone receptor expression in vivo: an experimental study in mice.

BACKGROUND: Vinclozolin is a fungicide that has been reported to have anti-androgenic effects in rats. We have found that in utero exposure to natural or synthetic progesterones can induce hypospadias in mice, and that the synthetic progesterone medroxyprogesterone acetate (MPA) feminizes male and virilizes female genital tubercles. In the current work, we selected a relatively low dose of vinclozolin to examine its in utero effects on the development of the genital tubercle, both at the morphological and molecular levels. METHODS: We gave pregnant dams vinclozolin by oral gavage from gestational days 13 through 17. We assessed the fetal genital tubercles from exposed fetuses at E19 to determine location of the urethral opening. After determination of gonadal sex, either genital tubercles were harvested for mRNA quantitation, or urethras were injected with a plastic resin for casting. We analyzed quantified mRNA levels between treated and untreated animals for mRNA levels of estrogen receptors alpha and beta, progesterone receptor, and androgen receptor using nonparametric tests or ANOVA. To determine effects on urethral length (males have long urethras compared to females), we measured the lengths of the casts and performed ANOVA analysis on these data. RESULTS: Our morphological results indicated that vinclozolin has morphological effects similar to those of MPA, feminizing males (hypospadias) and masculinizing females (longer urethras). Because these results reflected our MPA results, we investigated the effects of in utero vinclozolin exposure on the mRNA expression levels of androgen, estrogen alpha and beta, and progesterone receptors. At the molecular level, vinclozolin down-regulated estrogen receptor alpha mRNA in females and up-regulated progesterone receptor mRNA. Vinclozolin-exposed males exhibited up-regulated estrogen receptor alpha and progesterone receptor mRNA, effects we have also seen with exposure to the synthetic estrogen, ethinyl estradiol. CONCLUSION: The results suggest that vinclozolin virilizes females and directly or indirectly affects progesterone receptor expression. It also affects estrogen receptor expression in a sex-based manner. We found no in vivo effect of vinclozolin on androgen receptor expression. We propose that vinclozolin, which has been designated an anti-androgen, may also exert its effects by involving additional steroid-signaling pathways.

Analysis of Variance↗
PubMed2001

Factors affecting R6 fungicide toxicity on sea urchin fertilization and early development: roles of exposure routes and mixture components.

A technical fungicide mixture, R6 and its components, cymoxanil (CYM) and cupric oxychloride (Cu-OCl), were tested by sea urchin bioassays (Paracentrotus lividus and Sphaerechinus granularis). A set of toxicity endpoints was evaluated including both lethal and sublethal effects with the following endpoints: (a) acute embryotoxicity, (b) developmental defects, (c) changes in sperm fertilization success, (d) transmissible damage from sperm to the offspring, and (e) cytogenetic abnormalities. Acute effects on developing embryos were observed as early (prehatch) mortality at R6 levels > or =25 microg/ml. The pesticide mixture R6 was tested at realistic concentrations, ranging from 25 ng/ ml to 2.5 microg/ml, and the two components, CYM and Cu-OCl, were tested, either alone or in mixture, at concentrations equal to their levels in the corresponding R6 solutions. R6 was either dissolved in filtered seawater (water only, W-O), or spiked in "pristine" silt-clay sediment or soil samples before bioassays. Developmental toxicity of R6, following W-O dissolution, displayed a significant dose-related increase of larval malformations and differentiation arrest at concentrations of 750 ng/ml to 2.5 microg/ml both in P. lividus and in S. granularis larvae. Developmental toxicity was removed in spiked sediment up to R6 nominal levels (25 microg/ml), 10-fold above the embryotoxic R6 levels in W-O exposure. No significant developmental toxicity was exerted by CYM or Cu-OCl (W-O exposure) up to their concentrations equivalent to 2.5 microg/ml R6. The laboratory-prepared mixture of CYM and Cu-OCl, in the same concentration range, only resulted in minor effects, as larval retardation, suggesting the presence of toxic impurities (or additional components) in the R6 formulation. When sperm from either P. lividus or S. granularis were exposed to R6 before fertilization, a W-O exposure resulted in a dose-related decrease in fertilization of P. lividus sperm (up to 250 microg/ml R6), whereas S. granularis sperm underwent a significant increase of fertilization rate at the highest R6 nominal levels (up to 25 microg/ml). Equivalent CYM or Cu-OCl levels were ineffective on sperm fertilization success in both species. The offspring of S. granularis sperm exposed to 25 microg/ml R6 showed a significant increase in larval malformations, which were not detected in the offspring of R6-exposed P. lividus sperm. Again, CYM or Cu-OCl was unable to exert any transmissible damage from sperm to the offspring in either species. The present study raises the case of possible discrepancies between toxicity of a technical mixture and of its analytical-grade components, also providing evidence for a loss of pesticide toxicity following dispersion in an environmental matrix such as sediment or soil.

Acetamides↗
PubMed2003

A benzimidazole fungicide, benomyl, and its metabolite, carbendazim, induce aromatase activity in a human ovarian granulose-like tumor cell line (KGN).

Endocrine disruptor chemicals are known to cause a range of abnormalities in sexual differentiation and reproduction. One mechanism underlying such effects may be via alteration of aromatase activity, which is responsible for estrogen production. A good screening system for identifying endocrine disruptors has long been desired. We have recently established a human ovarian granulosa-like tumor cell line, KGN, which possesses a relatively high level of aromatase expression and is considered a useful mammalian model for investigating the in vitro effects of various chemicals on aromatase activity. In this study we screened 55 different candidate chemicals for endocrine disruptors by assaying aromatase activity. Only benomyl, known as both a benzimidazole fungicide and a microtubule-interfering agent, was found to induce aromatase activity in association with increased levels of aromatase mRNA in KGN cells. The effect of benomyl was presumed to be mediated by its metabolite carbendazim, because it produced an effect equivalent to that of benomyl. The mechanism underlying the benomyl-induced increase in aromatase activity appears independent of the cAMP-protein kinase A pathway. Treatment with taxol, another class of microtubule-interfering agents, also caused induction of aromatase in KGN cells. Both benomyl and taxol changed KGN cell morphology, including the development of cell roundness and a disorganized network of microtubules. These results indicate that benomyl is a potential endocrine disruptor that provides a novel estrogenicity and operates through a microtubule-interfering mechanism.

Aromatase↗
PubMed1985

Effects of buthiobate, a fungicide, on cytochrome P-450 of rat liver microsomes.

Effects of buthiobate (S-butyl S'-p-tert-butylbenzyl N-3-pyridyldithiocarbonimidate), a fungicide which inhibits lanosterol 14 alpha-demethylation catalyzed by a cytochrome P-450 (P-450 14DM) of yeast, on cytochrome P-450 of rat liver microsomes were studied. Buthiobate bound to limited forms of cytochrome P-450 in the microsomes with three different Kd values, 0.38, 1.56 and 13.6 microM. Buthiobate inhibited lanosterol 14 alpha-demethylase activity of the microsomes with a 50%-inhibition concentration of 0.4 microM. This concentration was comparable to the lowest Kd of buthiobate for the microsomal cytochrome P-450 and also to the 50%-inhibition concentration of the inhibitor for lanosterol 14 alpha-demethylation by yeast P-450 14DM. Buthiobate partially inhibited 7-ethoxycoumalin O-deethylase activity of the microsomes but inhibited neither benzphetamine N-demethylation nor p-nitroanisole O-demethylation. These observations suggest that cytochrome P-450s catalyzing drug oxidations are rather insensitive to buthiobate. These observations indicate that buthiobate is an unique inhibitor for hepatic microsomal cytochrome P-450 system, which inhibits cholesterol biosynthesis effectively but causes a little effect on drug oxidations.

Animals↗
PubMed2000

[In vivo toxicity, lipid peroxide lowering, and glutathione, ascorbic acid and copper elevation induced in mouse liver by low dose of oxine-copper, a fungicide].

While oxine-copper (OxCu) is generally used as an agricultural fungicide and induces a harmful effect on ecosystems, little information is available regarding a toxic effect of OxCu on mammals. In this article, we examined in vivo induction of toxicity and change of levels of glutathione and ascorbic acid, major biological antioxidants, lipid peroxide and copper (Cu) in liver and kidney 4 h and 24 h after intraperitoneal administration of OxCu at a low dose (0.05 mmol/kg) to mice. Increased hepatic ascorbic acid and Cu levels were found at 4 h after the treatment. In addition, body weight change was lowered and serum glutamic pyruvic transaminase activity was elevated significantly compared to control at 24 h after the treatment, suggesting induction of systemic and hepatic toxicity respectively. These were accompanied by lowered lipid peroxide level and enhanced glutathione, ascorbic acid and Cu levels in the mouse liver. On the other hand, OxCu induced no elevation in serum urea nitrogen concentration 4 h and 24 h after the treatment, suggesting no induction of nephrotoxicity, accompanied by no change in renal lipid peroxide, glutathione, ascorbic acid and Cu levels. These results suggest that hepatic Cu elevation may induce hepatotoxicity and no renal Cu elevation may lead to no induction of nephrotoxicity after the treatment with OxCu.

Animals↗
PubMed2000

Fungicidal and herbicidal activities of berberine related alkaloids.

The 23 quaternary and tertiary protoberberines related to berberine were tested for in vitro and/or in vivo fungicidal and herbicidal activities. Among the compounds tested, there was some activity observed with some of only the protoberberinium salts, but not sufficiently strong or broad spectrum for agrochemical use. From the structure-activity point of view, some features can be pointed out.

Berberine Alkaloids↗
PubMed2003

Putative homologs of SSK22 MAPKK kinase and PBS2 MAPK kinase of Saccharomyces cerevisiae encoded by os-4 and os-5 genes for osmotic sensitivity and fungicide resistance in Neurospora crassa.

We cloned and characterized Neurospora NcSSK22 and NcPBS2 genes, similar to yeast SSK22 mitogen-activated protein (MAP) kinase kinase kinase and the PBS2 MAP kinase kinase genes, respectively. Disruptants of the NcSSK22 gene were sensitive to osmotic stress and resistant to iprodione and fludioxonil. Their phenotypes were similar to those of osmotic-sensitive (os) mutants os-1, os-2, os-4, and os-5. The os-4 mutant strain transformed with the wild-type NcSSK22 gene grew on a medium containing 4% NaCl and was sensitive to iprodione and fludioxonil. In contrast, the NcPBS2 gene complemented the osmotic sensitivity and fungicide resistance of the os-5 mutant strain. We sequenced the NcPBS2 gene of the os-5 mutant strain (NM216o) and found five nucleotides deleted within the kinase domain. This result suggests that the gene products of os-4 and os-5 are components of the MAP kinase cascade, which is probably regulated upstream by two-component histidine kinase encoded by the os-1/nik1 gene.

Amino Acid Sequence↗
PubMed1997

Thyroid hormones and cytogenetic outcomes in backpack sprayers using ethylenebis(dithiocarbamate) (EBDC) fungicides in Mexico.

Ethylenebis(dithiocarbamate) (EBDC) fungicides are used heavily in the United States. EBDCs (e.g., mancozeb, maneb) are metabolized to ethylene thiourea (ETU). The EPA classifies ETU as a carcinogen, based on thyroid and other cancers in rodents, and has restricted the use of EBDCs, while requiring workers to use protective equipment. There are no data on the potential carcinogenicity of EBDCs in humans, and there is only one study on human genotoxicity. ETU is known to cause decreases of thyroxine (T4) and increases in thyroid-stimulating hormone (TSH) in rodents. We have studied cytogenetic outcomes and serum thyroid hormone levels among 49 heavily exposed workers without protective equipment spraying EBDC on tomatoes in Mexico. We also studied 14 lightly exposed landowners and 31 nonexposed controls. Urinary ETU was used to compare exposure between groups. We found an increase in TSH (p = 0.05) among applicators compared to controls, but no decrease in thyroid hormone (T4). We found increases in sister chromatid exchange (p = 0.03) and in chromosome translocations (chromosome aberrations that persist through cell division) for applicators compared to controls (p = 0.05). However, the subset of reciprocal translocations showed a lesser increase (p = 0.24). Our data suggest that EBDCs affect the thyroid gland and the lymphocyte genome among heavily exposed workers. However, our data are limited to subclinical outcomes, are of borderline statistical significance, and should be interpreted with caution.

Adult↗
PubMed1999

The fungicide carbendazim induces meiotic micronuclei in the spermatids of the rat testis.

Whether the fungicide carbendazim affects the meiotic spermatocytes and consequently induces chromosome aberrations in the spermatids was determined in the adult rat testis using the micronucleus test. Round spermatids containing micronuclei (MN) were significantly increased in number at stages I and V on days 1 and 4.5 after treatment with carbendazim (100 mg/kg), respectively (p<0.05). Immunocytochemistry indicated that approximately 68% of the carbendazim-induced MN contained kinetochores. These results suggest that carbendazim induces chromosome aberrations in spermatids with a high incidence of aneuploidy.

Animals↗
PubMed2000

Histopathology of the male reproductive system induced by the fungicide benomyl.

Benomyl is an effective fungicide that has been in use for many years. This chemical and its primary metabolite, carbendazim, are microtubule poisons that are relatively nontoxic to all mammalian organs, except for the male reproductive system. Its primary effects, at moderate to low dosages, are on the testis, where it causes sloughing of germ cells in a stage-dependent manner. Sloughing is caused by the effects of the chemical on microtubules and intermediate filaments of the Sertoli cell. These effects spread to dividing germ cells and also lead to abnormal development of the head of elongating spermatids. At higher dosages, it causes occlusion of the efferent ducts, blocking passage of sperm from the rete testis to epididymis. The mechanism of occlusion appears to be related to fluid reabsorption, sperm stasis, followed by leukocyte chemotaxis, sperm granulomas, fibrosis and often the formation of abnormal microcanals. The occlusion results in a rapid swelling of the testis and ultimately seminiferous tubular atrophy and infertility. In conclusion, studies that reveal long term testicular atrophy following chronic or subchronic exposure to a toxicant should be re-examined for histopathological lesions in the efferent ductules and head of the epididymis. Lesions in the male track that cause blockage may induce permanent testicular damage and a decrease in sperm production.

Animals↗
PubMedDate not supplied

Are biological antagonists an alternative to synthetic fungicides for preventing postharvest diseases of fruits and vegetables?

In recent years, both the public and health authorities have become increasingly concerned about the presence of pesticides in our food supply and the environment. As a direct result of this mounting concern, research efforts for the development of alternative methods for the control of postharvest diseases of fruits and vegetables have been intensified. Considerable attention has been placed on assessing the potential of the use of biological antagonists as a viable alternative to the use of synthetic fungicides. Naturally occurring microbial antagonists have been shown to control several rot pathogens on diverse commodities. Such antagonists have various modes of action: antibiosis or competition for nutrients and space or both, induction of resistance in the host tissue, and direct interaction with the pathogen. The commercialization of certain antagonists to control postharvest decay of fruits and vegetables appears to be feasible and may present an alternative to synthetic pesticides.

Agriculture↗