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At least 937 records · Page 52Linked to original sources
PubMed2000

Genotoxic and mono-oxygenase system effects of the fungicide maneb.

The in vivo effects of a commercial preparation of maneb on mono-oxygenase activities of hepatic microsomes of basal and induced rats were examined. In vitro experiments with the D7 strain of yeast Saccharomyces cerevisiae were also performed. In both basal and induced rats maneb caused a decrease in cytochrome P-450 content and aniline hydroxylase. Immunoblotting analysis using anti-P-450 IIE1 antibodies confirmed the data obtained for aniline hydroxylase activity. Maneb was toxic in cells of S. cerevisiae. On the basis of in vivo and in vitro experiments it can be concluded that maneb possesses a toxic activity attributable to its main metabolite ethylene thiourea. Immunoblotting analysis indicates that maneb biotransformation influences the IIEI P-450 isoform.

Aniline Hydroxylase↗
PubMed1998

A study of the lethal and sublethal toxicity of polyphase P-100, an antisapstain fungicide containing 3-iodo-2-propynyl butyl carbamate (IPBC), on fish and aquatic invertebrates.

The acute toxicity of Polyphase P-100, an antisapstain wood preservative that contains 97% 3-iodo-2-propynyl butyl carbamate (IPBC), was determined for three species of fish (coho salmon, rainbow trout, and starry flounder) and three species of aquatic invertebrates (Daphnia magna, Hyalella azteca, and Neomysis mercedis). The 96-h LC50 values for the various fish species exposed to Polyphase P-100 ranged from 95 ppb for coho smolts (Oncorhynchus kisutch) to 370 ppm for juvenile starry flounder (Platichthys stellatus). The sensitivity of coho to Polyphase P-100 was altered by their developmental stage. Coho embryos were six to nine times more tolerant of Polyphase P-100 than coho alevins, which were twice as tolerant as coho smolts. The 48-h LC50 values for the invertebrates D. magna, H. azteca, and N. mercedis were 40 ppb, 500 ppb, and 2,920 ppb, respectively. In addition to a wider range of sensitivity to Polyphase P-100 compared with the fish species, the invertebrate species were characterized by a shallower concentration-response. In acute, 24-h sublethal tests with juvenile starry flounder and rainbow trout, there was no primary or secondary stress response (changes in hematocrit, leucocrit, hemoglobin concentration, plasma lactate concentration, and plasma cortisol concentration) at concentrations up to 50% of the 96-h LC50 value. The acute toxicity of a 1:8 mixture of Polyphase P-100 and Bardac 2280 (another antisapstain compound that contains didecyldimethylammonium chloride [DDAC] as the active ingredient) was close to additive for fish, but not for invertebrate species. The acute toxicity of the mixture was seven to eight times more than additive for H. azteca, but two to three times less than additive for D. magna. Some sublethal stress responses were revealed with the mixture that were not observed with the test chemicals alone.

Animals↗
PubMed2005

Sphingolipids influence the sensitivity of lipid bilayers to fungicide, syringomycin E.

Sphingolipids with long chain bases hydroxylated at the C4 position are a requisite for the yeast, Saccharomyces cerevisia, to be sensitive to the ion channel forming antifungal agent, syringomycin E (SRE). A mutant S. cerevisiae strain, Deltasyr2, having sphingolipids with a sphingoid base devoid of C4-hydroxylation, is resistant to SRE. To explore the mechanism of this resistance, we investigated the channel forming activity of SRE in lipid bilayers of varying composition. We found that the addition of sphingolipid-rich fraction from Deltasyr2 to the membrane-forming solution (DOPS/DOPE/ergosterol) resulted in lipid bilayers with lower sensitivity to SRE compared with those containing sphingolipid fraction from wild-type S. cerevisiae. Other conditions being equal, the rate of increase of bilayer conductance was about 40 times slower, and the number of SRE channels was about 40 times less, with membranes containing Deltasyr2 versus wild-type sphingolipids. Deltasyr2 sphingolipids altered neither SRE single channel conductance nor the gating charge but the ability of SRE channels to open synchronously was diminished. The results suggest that the resistance of the Deltasyr2 mutant to SRE may be partly due to the ability of sphingolipids without the C4 hydroxyl group to decrease the channel forming activity of SRE.

Electric Conductivity↗
PubMed1990

DNA cleavage by phenylhydroquinone: the major metabolite of a fungicide o-phenylphenol.

The interaction of o-phenylphenol (OPP) and its metabolites with DNA was examined. As a model system, the reactivities of OPP and its metabolites with DNA were studied by using pUC18 DNA. The major metabolite formed in vitro from OPP by mixed function oxidase was phenylhydroquinone (PHQ). This result corresponds to the findings that PHQ in the form of glucuronide conjugate was the main product detected in bladder of OPP fed rats in vivo. When supercoiled pUC18 DNA (form I) was incubated with PHQ at concentrations from 1 X 10(-6) M to 2 X 10(-1) M, DNA strand scission by PHQ was observed at a concentration as low as 1 X 10(-5) M and the amount of linear form (form III) increased with increasing PHQ concentration. PHQ causes DNA strand scission. The DNA cleavage by OPP and phenyl-p-benzoquinone (PBQ) was barely detectable. The DNA cleavage by PHQ was inhibited by superoxide dismutase (SOD), catalase and several oxygen radical scavengers such as polyethylene glycol, tert-butanol, dimethyl sulfoxide, sodium azide, sodium benzoate, bovine serum albumin and methionine. The production of superoxide radical from PHQ was confirmed by cytochrome c reduction assay. These results indicate that the oxygen radicals such as superoxide, hydroxyl radicals and some others generated in the process of oxidation of PHQ in aqueous solution are responsible for the DNA cleavage. In order to identify the sites of cleavage of DNA by PHQ, a 5'-end 32P-labeled 206 base-pair EcoRI-BglI fragment of pUC18 DNA was incubated with PHQ. The DNA was then analyzed by sequencing gel electrophoresis followed by autoradiography. When the DNA was incubated with PHQ and further treated with piperidine, cleavage was detected relatively more frequently at guanine residues. The attack seemed to occur at guanine residues in general, but was not restricted to guanines with specific residues in the vicinity.

Animals↗