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1.
2.
Photosynthesis under conditions known to favour glycollate excretionby algae did not result in glycollate excretion in a strainof Chlorella pyrenoidosa unless an inhibitor of glycollate oxidase,-hydroxypyridin-2yl-methane sulphonate (-HPMS), was present.This inhibitor increased the total amount of glycollate presentin the supernatant from the cells during photosynthetic carbondioxide fixation and gave accumulation of 14C in glycollateduring 14CO2 fixation under conditions favouring glycollatesynthesis. At pH 8.3 -HPMS did not stimulate photosynthetic14CO2 fixation in C. pyrenoidosa as occurs with some algae.Photoassimilation of acetate was inhibited by -HPMS, and thiswas shown to result from acetyl-CoA synthetase inhibition by-HPMS. 相似文献
3.
FAHIEMH NIROOMAND CATHY LORD 《Journal of Rapid Methods and Automation in Microbiology》1994,3(2):85-96
Four different commercial kits (EHEC-TEK of Organon Teknika, Durham, NC; HEC O157 of 3M, St. Paul, MN; and Coline dipstick and Coline one-step of AMP-COR Inc., Camden, NJ) were evaluated for the detection and recovery of E. coli O157:H7from 75 fresh meat samples and 23 artificially inoculated beef and pork samples. Of the total 75 samples tested, 21 (28%) were presumptive positive by HEC O157 and Coline dipstick, 18 (24%) by Coline one-step, and 12 (16%) by EHEC-TEK. None of the presumptive positive samples by any of the methods was confirmed as E. coli O157:H7 (false positive). Of the 23 positive spiked samples tested, 23 were recovered by Coline dipstick and one-step (100%), 22 (95.6%) by HEC O157, and 20 (86.9) were recovered by EHEC-TEK. In the confirmation step 17 of the 23 spiked samples produced characteristic colonies on MacConkey sorbitol agar (Difco) with 5-bromo-4-chloro-3-indoxy-β-D-glucuronide (Biosynth International) (MSA-BCIG) and were confirmed as E. coli O157:H7. No characteristic colonies on MSA-BCIG were detected for 6 of the spiked samples with initial inoculum levels of between 2 to 70 cells/g and, therefore, were not confirmed as E. coli O157:H7. A better enrichment medium, as well as improved selective plating and confirmation techniques, are needed to enhance the selective growth of E. coli O157:H7 and provide lower detection levels. 相似文献
4.
Chlormequat chloride labelled with 14C was applied to the thirdleaf of Proctor barley and Maris Dove wheat; after 1 d lessthan a fifth could be washed off with water. More 14C-labelledmaterial moved from treated areas of wheat than of barley toaccumulate in tips of treated leaves, younger main-stem leaves,main stems, and ears. Relatively small amounts of radioactivematerial accumulated in roots, but less in wheat than barley.About 80% of the radioactivity was recovered from plants upto 1 week after application, but the amounts recovered in aqueouswashings and extracts decreased faster from wheat than frombarley. 相似文献
5.
6.
THE CONVERSION OF GLYCERATE INTO PYRUVATE BY CHLORELLA EXTRACTS 总被引:1,自引:1,他引:0
7.
Processes affecting the toxicity of diazinon to a susceptible and a resistant strain of houseflies were examined. More evidence was obtained to show that slower penetration of diazinon through the integument of resistant flies is a cause of resistance. Small amounts of two decomposition products were found in both strains. The decomposition mechanisms, in these strains were differently distributed and, although detoxication of diazinon in the two strains is quantitatively similar and small, it may contribute to resistance. Traces of diazoxon were detected when diazinon was incubated with tissue extracts of either strain. Tissue extracts of resistant, but not of susceptible, flies decomposed significant amounts of diazinon in 1 hr. and the ability to decompose diazoxon seems to be an important cause of resistance. Tissues of both strains sorbed diazinon from aqueous solution similarly; the quantities sorbed were large and suggest that sorption may increase the amount of poison needed inside the insects to kill, by between five and forty times. 相似文献
8.
K. A. LORD 《The Annals of applied biology》1950,37(1):123-126
Using insecticidal dusts of D.D.T., γ-benzene hexachloride and D.N.C. under the experimental conditions, comparatively large changes in the amount of material of a given concentration are necessary in order to give appreciable differences in mortality, but small changes in the concentration of the poison will produce large differences in toxicity with a given amount applied. This relationship would appear to hold with a number of insecticides. 相似文献
9.
The preparation of an extract of the mealworm larvae, Tenebrio molitor L. which hydrolyses ethyl butyrate and o -nitrophenyl acetate, but not acetylcholine, is described. The inhibition of this esterase by TEPP-containing materials and parathion was determined.
An enzyme that hydrolysed o -nitrophenyl acetate and was inhibited by a TEPP-containing material was demonstrated in the five other insect species used.
The relative toxicities as contact insecticides to adult Tribolium castaneum Hbst. of ten samples of TEPP-containing materials were compared with their relative activities as esterase inhibitors. There was not an exact quantitative correlation between TEPP content estimated chemically, insecticidal activity and anti-esterase activity; but the correlation was sufficient to suggest interdependence of these factors.
Eggs of Diataraxia oleracea L. and Ephestia kühniella Zell, were shown to contain an enzyme that hydrolysed o -nitrophenyl acetate and was inhibited by the TEPP-containing materials. This enzyme was present in eggs less than 24 hr. old, i.e. before there was any visible signs of development. The TEPP was shown to be toxic to these eggs and in high concentrations kills at an early stage of development before differentiation of the nervous system. This, in conjunction with the other evidence, suggests that esterases other than the choline-esterase of the nervous system are important when considering the toxic action of these compounds.
Comparison of the anti-esterase activity and toxicity of parathion and TEPP-containing materials as insecticides showed that although the TEPP materials were the more potent enzyme inhibitors, parathion was the more potent contact insecticide to five species of insects. This appears to be due to the relative instability of TEPP. The study of the rates of action of the two poisons applied at different concentrations supports this view. 相似文献
An enzyme that hydrolysed o -nitrophenyl acetate and was inhibited by a TEPP-containing material was demonstrated in the five other insect species used.
The relative toxicities as contact insecticides to adult Tribolium castaneum Hbst. of ten samples of TEPP-containing materials were compared with their relative activities as esterase inhibitors. There was not an exact quantitative correlation between TEPP content estimated chemically, insecticidal activity and anti-esterase activity; but the correlation was sufficient to suggest interdependence of these factors.
Eggs of Diataraxia oleracea L. and Ephestia kühniella Zell, were shown to contain an enzyme that hydrolysed o -nitrophenyl acetate and was inhibited by the TEPP-containing materials. This enzyme was present in eggs less than 24 hr. old, i.e. before there was any visible signs of development. The TEPP was shown to be toxic to these eggs and in high concentrations kills at an early stage of development before differentiation of the nervous system. This, in conjunction with the other evidence, suggests that esterases other than the choline-esterase of the nervous system are important when considering the toxic action of these compounds.
Comparison of the anti-esterase activity and toxicity of parathion and TEPP-containing materials as insecticides showed that although the TEPP materials were the more potent enzyme inhibitors, parathion was the more potent contact insecticide to five species of insects. This appears to be due to the relative instability of TEPP. The study of the rates of action of the two poisons applied at different concentrations supports this view. 相似文献
10.
FERTILIZATION IN FISH AND LAMPREYS 总被引:1,自引:0,他引:1
LORD ROTHSCHILD 《Biological reviews of the Cambridge Philosophical Society》1958,33(3):372-389