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11.
J. Guan A. Kerkenaar M. A. De Waard 《European journal of plant pathology / European Foundation for Plant Pathology》1989,95(1):73-86
Imazalil differentially inhibited dry weight increase of 10-hour-old germlings of wild-type and DMI-resistant isolates ofPenicillium italicum in liquid malt cultures. EC50 values ranged from 0.005 to 0.27 μg ml?1. In all isolates ergosterol constituted the major sterol (over 95% of total sterols) in the absence of the fungicide. Therefore, DMI-resistance cannot be associated to a deficiency of the C-14 demethylation enzyme in the ergosterol biosynthetic pathway. Imazalil treatment at concentrations around EC50 values for inhibition of mycelial growth resulted in a decrease in ergosterol content and a simultaneous increase in 24-methylene-24,25-dihydrolanosterol content in all isolates. A correlation existed between the imazalil concentration necessary to induce such changes in sterol composition and the EC50 values for inhibition of mycelial growth of the different isolates. The reason for the differential effects of imazalil on sterol composition in the variousP. italicum isolates may be due to decreased accumulation of the fungicide in the mycelium and to other yet non-identified mechanisms of resistance. 相似文献
12.
H.H. Hoppe A. Kerkenaar A. Kaars Sijpesteijn 《Pesticide biochemistry and physiology》1976,6(5):413-421
3-Phenylindole is an antimicrobial compound active towards many fungi and gram-positive bacteria. At 5 μg/ml it inhibits growth of Aspergillus niger. Higher concentrations (50 μg/ml) also suppress spore germination; they do not kill the fungus. Dry weight of the fungus still increases for 1 or 2 days after fungicide treatment. The toxicant has no effect on O2 uptake even at higher concentrations (100 μg/ml). The compound markedly affects composition of the lipid fraction of A. niger inducing a decrease in phospholipid concentration with a coincident increase in free fatty acids. Sterol pattern and sterol concentration were not affected. Antifungal activity was reversed by phospholipids added to the medium. 3-Phenylindole induced a slight leakage of 32P-labeled compounds from the treated cells under growth conditions but not under nongrowth conditions. A strain of A. niger resistant to 3-phenylindole had the same phospholipid and sterol pattern as the wild type, but the level of both components was higher (40–60%). The 3-phenylindole-resistant strain showed resistance to triarimol and pimaricin. The wild type and the resistant strain both took up 3-phenylindole quite rapidly and accumulated it in the mycelium. 3-Phenylindole possibly interferes with phospholipid function in cell membranes, although the specific site of action has not yet been elucidated. 相似文献
13.
Antonius G. T. SCHUT Emily C. COOLEDGE Marc MORAINE Gerrie W. J. VAN DE VEN Davey L. JONES David R. CHADWICK 《农业科学与工程前沿(英文版)》2021,8(1):111-129
14.
In an attempt to indicate the site of action of tridemorph in ergosterol biosynthesis by Ustilago maydis the nature of the sterol intermediates accumulating in treated cells was studied. At low growth-inhibiting concentrations of the toxicant (10 and 15 μg/ml) decline of ergosterol content during 6 hr of incubation was accompanied by an accumulation of various sterol intermediates of which ergosta-8,14-dien-3β-ol appeared to be the major sterol. After isolation of this intermediate its identity was further confirmed by direct comparisonof its ultraviolet, glc, and mass spectrum with those of an authentic synthesized sample of ergosta-8,14-dien-3β-ol (ignosterol). Results indicate that toxicity of tridemorph is caused by a specific inhibitive effect on the enzyme Δ14-reductase which is responsible for double-bond reduction in sterol biosynthesis. 相似文献
15.
Tridemorph (2,6-dimethyl-N-tridecylmorpholine) was active against representative of nearly all taxonomic groups of fungi; gram-positive bacteria were also sensitive although gram-negative were not. Tridemorph, 3–10 μg/ml, inhibited the multiplication of sporidia of Ustilago maydis more strongly than the increase of dry weight. The treated sporidia appeared swollen, multicellular, and sometimes branched. Unsaturated lipophilic compounds like α-tocopherol and trilinolein alleviated the toxicity of tridemorph to Botrytis allii and U. maydis. Protein and RNA syntheses were inhibited slightly. DNA synthesis was rather strongly affected already after 2 hr. Lipid synthesis was first inhibited but later stimulated. At an early stage (2 hr) treated cells differed already from control cells by a higher content of free fatty acids. Tridemorph also inhibited sterol biosynthesis. The antimicrobial spectrum, the characteristic morphology of treated cells of U. maydis, the observations on cross-resistance, the alleviating effect of unsaturated lipophilic compounds, and the alterations in neutral lipid pattern suggest strong similarity of the mode of action of tridemorph with that of the known inhibitors of sterol biosynthesis. 相似文献
16.
Pig performance increases with the addition of dl-methionine and l-lysine to ensiled cassava leaf protein diets 总被引:1,自引:0,他引:1
Two studies were conducted to determine the impact of supplementation of diets containing ensiled cassava leaves as the main
protein source with synthetic amino acids, dl-methionine alone or with L-lysine. In study 1, a total of 40 pigs in five units, all cross-breds between Large White and Mong Cai, with an average initial
body weight of 20.5 kg were randomly assigned to four treatments consisting of a basal diet containing 45% of dry matter (DM)
from ensiled cassava leaves (ECL) and ensiled cassava root supplemented with 0%, 0.05%, 0.1% and 0.15% dl-methionine (as DM). Results showed a significantly improved performance and protein gain by extra methionine. This reduced
the feed cost by 2.6%, 7.2% and 7.5%, respectively. In study 2, there were three units and in each unit eight cross-bred (Large
White × Mong Cai) pigs with an initial body weight of 20.1 kg were randomly assigned to the four treatments. The four diets
were as follows: a basal diet containing 15% ECL (as DM) supplemented with different amounts of amino acids l-lysine and dl-methionine to the control diet. The results showed that diets with 15% of DM as ECL with supplementation of 0.2% lysine +0.1%
dl-methionine and 0.1% lysine +0.05% dl-methionine at the 20–50 kg and above 50 kg, respectively, resulted in the best performance, protein gain and lowest costs
for cross-bred (Large White × Mong Cai) pigs. Ensiled cassava leaves can be used as a protein supplement for feeding pigs
provided the diets contain additional amounts of synthetic lysine and methionine. 相似文献
17.
H.H. Hoppe A. Kerkenaar A. Kaars Sijpesteijn 《Pesticide biochemistry and physiology》1976,6(5):422-429
Low concentrations of 3-PI(3-phenylindole) inhibit several uptake and biosynthetic processes in liquid cultures of Aspergillus niger. The incorporation of 32Pi into phospholipids, [14C]uridine into nucleic acids, and [14C]phenylalanine into proteins was inhibited and the uptake of all three precursors was reduced. Studies on an in vitro interaction between 3-phenylindole and phospholipids showed, that at about equimolar concentrations 3-phenylindole prevents phospholipids from swelling in water. At the same ratio a decrease of the absorption intensity of the NH-band of 3-phenylindole was observed in ir spectra. Moreover, the maxima of the uv spectrum of 3-phenylindole shifted after addition of a sonicated phospholipid suspension. It is suggested that binding to phospholipids is the first effect of 3-phenylindole. Apparently this affects, consequently, several membrane-bound reactions, i.e., transport and biosynthetic processes. 相似文献
18.
The systemic acylalanines metalaxyl and furalaxyl proved in vitro highly selective to fungi of the order of the Peronosporales, the former being somewhat more active than the latter. Various other fungal, and bacterial, species did not show sensitivity to the toxicants. Metalaxyl was strikingly more active on Pythium splendens and Phytophthora cinnamomi at low than at high temperature. With Phytophthora species metalaxyl displayed improved activity in combination with sodium dodecylsulphate and Triton X-100. Neither the composition of the medium nor its pH influenced activity. None of many compounds tested could antagonize their effect. The fungitoxicity caused by metalaxyl in the gas phase was strikingly better than that of furalaxyl against P. splendens. The toxicants had little effect on germination of the hyphal swellings of P. splendens, but had significant influence on the subsequent hyphal development. This included reduced growth, abnormal variation in the fungal thickness, and inhibition of the formation of hyphal swellings. Metalaxyl and furalaxyl were fungistatic at minimal inhibitory concentration (MIC) values during the first 24 hr. Thereafter, the toxicants became fungicidal. Metalaxyl and furalaxyl did not inhibit respiration of P. splendens at MIC values or somewhat higher concentrations. Neither did metalaxyl inhibit the [14C]carbon dioxide evolution from externally supplied radiolabeled glucose. 相似文献
19.
J. Guan A. Kerkenaar M. A. De Waard 《European journal of plant pathology / European Foundation for Plant Pathology》1989,95(Z1):73-86
Imazalil differentially inhibited dry weight increase of 10-hour-old germlings of wild-type and DMI-resistant isolates ofPenicillium italicum in liquid malt cultures. EC50 values ranged from 0.005 to 0.27 g ml–1. In all isolates ergosterol constituted the major sterol (over 95% of total sterols) in the absence of the fungicide. Therefore, DMI-resistance cannot be associated to a deficiency of the C-14 demethylation enzyme in the ergosterol biosynthetic pathway. Imazalil treatment at concentrations around EC50 values for inhibition of mycelial growth resulted in a decrease in ergosterol content and a simultaneous increase in 24-methylene-24,25-dihydrolanosterol content in all isolates. A correlation existed between the imazalil concentration necessary to induce such changes in sterol composition and the EC50 values for inhibition of mycelial growth of the different isolates. The reason for the differential effects of imazalil on sterol composition in the variousP. italicum isolates may be due to decreased accumulation of the fungicide in the mycelium and to other yet non-identified mechanisms of resistance.Imazalil remt differentieel de toename in drooggewicht van 10-uur-oude gekiemde sporen van wild-type en DMI-resistente isolaten vanPenicillium italicum in vloeistofcultures van moutextract. De EC50 waarden voor groei van de verschillende isolaten lopen uiteen van 0,005 tot 0,27 g ml–1. In afwezigheid van het fungicide is in alle isolaten ergosterol het belangrijkste sterol (meer dan 95% van het totaal). DMI-resistentie kan daarom niet in verband staan met deficiëntie van het C-14 demethyleringsenzym in de ergosterol biosynthese. Imazalilbehandeling van mycelium bij concentraties rond de EC50 waarde voor groeiremming, resulteerde bij alle isolaten in een afname van het ergosterolgehalte en een gelijktijdige toename van het gehalte aan 24-methyleen-24,25-dihydrolanosterol. Er bestaat dus een nauwe correlatie tussen de imazalilconcentratie die noodzakelijk is om vergelijkbare veranderingen in sterolsamenstelling te induceren en de EC50 waarde voor remming van myceliumgroei van de verschillende isolaten. De differentiële effecten van imazalil op de sterolsamenstelling van de verschillendeP. italicum isolaten kunnen worden veroorzaakt door verminderde accumulatie van het fungicide in het mycelium en door andere, nog niet geïdentificeerde resistentiemechanismen. 相似文献
20.
Wijnand B. Nimmo Antonius G. M. Willems Kees D. Joustra Arie Verloop 《Pest management science》1986,17(4):403-411
The fate of 4-chlorophenylurea in soils was studied with two preparations: one labelled with 14C in the phenyl ring and the other in the carbonyl group. The initial dose of 1 mg kg?1 decreased to 50% in about 5 weeks in aerobic sandy clay and in about 16 weeks in anaerobic hydrosoil. Soil treatment with each of the preparations resulted in the release of [14C]carbon dioxide, pointing to decarbonylation and ring opening. The fraction of non-extractable (soil-bound) radioactivity increased during incubation. Quantities of ring-14C-labelled and carbonyl-14C-labelled bound residues differed strongly in the aerobic soil but only slightly in the anaerobic hydrosoil. It is assumed that two sorts of bound residues are formed from 4-chlorophenylurea: one is fairly stable and might consist of bound 4-chloroaniline or its transformation products, whereas the other is presumed to be a degradable derivative of 4-chlorophenylurea. 相似文献