共查询到20条相似文献,搜索用时 31 毫秒
1.
Four-year-old silver maple ( Acer saccharinum L.) saplings were trimmed and trunk injected with 14C-labeled uniconazole [(E)-1-(4-chlorophenyl)-4, 4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten3-ol] in May of 1987. Inhibition of shoot growth was observed in 1988 but not in 1987. The 14C-activity detected in the foliage during 1987 and 1988 increased in a linear fashion, and the maximum concentration reached in 1988 was about one third that reached in 1987. Approximately 7.1 and 2.3% of the total 14C-activity injected into the saplings was present in senescing foliage harvested in the fall of 1987 and 1988, respectively. Most of the 14C-activity in the saplings 17, 134, or 500 days after injection remained around the injection site. Between 29 and 49% of the 14C-activity found in the foliage collected in the fall was associated with metabolites rather than uniconazole, and there was no increase in the proportion in metabolites from 1987 to 1988, suggesting that metabolism occurred in the foliage and not the stem. 相似文献
2.
One-year-old ‘Golden Delicious’ apple trees grafted onto MM 106 rootstocks were injected in the rootstock stem (shank) with 14C-uniconazole to determine the extent to which uniconazole is translocated and degraded over the length of an average growing season. In 4 months, 16% of recovered 14C-activity was translocated to the new shoots. Most of the 14C-activity remained in the rootstock. Chromatographic evaluation of shoot extracts demonstrated that the 14C-activity associated with uniconazole decreased 49% in 4 months. However, shoot growth was still inhibited which suggests that the amount of uniconazole that was degraded did not interfere with the inhibition of gibberellin biosynthesis, probably due to the continuous translocation of uniconazole that occurred. 相似文献
3.
One-year-old Golden Delicious apple trees grafted onto MM 106 rootstocks were injected in the rootstock stem (shank) with 14C-uniconazole to determine the extent to which uniconazole is translocated and degraded over the length of an average growing season. In 4 months, 16% of recovered 14C-activity was translocated to the new shoots. Most of the 14C-activity remained in the rootstock. Chromatographic evaluation of shoot extracts demonstrated that the 14C-activity associated with uniconazole decreased 49% in 4 months. However, shoot growth was still inhibited which suggests that the amount of uniconazole that was degraded did not interfere with the inhibition of gibberellin biosynthesis, probably due to the continuous translocation of uniconazole that occurred. 相似文献
4.
A Yugoslavian strain of Cotesia rubecula (Marshall) ( Hymenoptera: Braconidae) was released in spring broccoli for control of the imported cabbageworm, Pieris rapae (L.), in Montgomery Co., Virginia, in 1987. C. rubecula reproduced and parasitized imported cabbageworm larvae in fall broccoli in 1987. It was found in moderate numbers in the
summer and fall crops in 1988, and by fall had dispersed 0.8 km from the original release site. However, no C. rubecula were detected in our broccoli plots in Montgomery Country in 1989 or 1990.
The hymenopteran hyperparasites Isdromas lycaenae (Walker) (Ichneumonidae), Spilochalcis torvina (Cresson) ( Chalcididae), and Tetrastichus galactopus (Ratzeburg) ( Eulophidae) were found attacking C. rubecula. Hyperparasites emerged from 31.8% and 41.1% of the C. rubecula cocoons in 1987 and 1988, respectively. T. galactopus was the most numerous hyperparasite in 1987, but S. torvina was dominant in 1988. Hyperparasite activity was low during early spring, but increased in July in both years. By August
1988, only hyperparasites emerged from the C. rubecula cocoons collected in the field. In spite of C. rubecula's success in overwintering, hyperparasites, especially S. torvina, may be a limiting factor in the establishment of C. rubecula in southwestern Virginia.
相似文献
5.
Fate of 14C-chlorpyrifos was studied in a model rice ecosystem. The level of 14C-residues in floodwater showed initially a rapid decline in first 10 days. These residues were observed till 30 days. The insecticide residues in soil did not show any appreciable build-up, thereby indicating that the residue levels of this insecticide may not be significant. Extractable residues were formed up to 10–13% of the applied 14C-activity during the period of 136 days, while the bound fraction of 14C-residues reached a maximum of 2.9% after 92 days. Algae and rice plants showed 14C-residues to the extent of only 0.01% of the applied 14C-activity. Rice grains did not show any residues at all. These results indicate that chlorpyrifos undergoes considerable degradation in rice soils and does not leave residues, which may be of environmental concern. 相似文献
6.
In this study, we determined whether the application of uniconazole alone or combined with ethephon could enhance the seed-filling rates in maize by regulating the endogenous hormone contents. Uniconazole was applied to the foliage at concentrations of 0 (CK), 25 (U25), 50 (U50) and 75 (U75) mg L−1 at the 12-leaf stage. In addition, uniconazole was applied to the foliage at the 12-leaf stage and ethephon at 10 days after silking stage at concentrations of 0 (CK), 25 mg L−1 uniconazole + 100 mg L−1 ethephon (U25 + E100), 50 mg L−1 uniconazole + 200 mg L−1 ethephon (U50 + E200) and 75 mg L−1 uniconazole + 300 mg L−1 ethephon (U75 + E300). Uniconazole applied alone or in combination with ethephon significantly improved ear characters and grain yield. Uniconazole applied alone or combination with ethephon significantly improved the dry matter accumulation in seeds and seed-filling rates. Uniconazole significantly increased the abscisic acid (ABA) and zeatin (Z) + zeatin riboside (ZR) contents of seeds, but reduced the gibberellic acid (GA) contents. The application of uniconazole combined with ethephon decreased the ABA, Z + ZR and GA contents in seeds. The ABA and Z + ZR contents were significantly positively correlated, whereas the GA content was negatively correlated with the maximum seed weight, maximum seed-filling rate and mean seed-filling rate. The application of uniconazole alone significantly improved the seed-filling rates in maize by regulating the endogenous hormone contents. Thus, we conclude that uniconazole application at 50 mg L−1 in the 12-leaf stage can enhance the maize production. 相似文献
7.
Seasonal courses of leaf CO 2 gas exchange in a growing season were examined in saplings of Thujopsis dolabrata var. hondai and Quercus mongolica var. grosseserrata in a cool temperate deciduous forest. Between the two tree species there were no large differences in the light compensation
point of leaf photosynthesis, except for the season of new leaf expansion. However, light-saturated rates of net photosynthesis
were obviously high in T. dolabrata var. hondai. Evergreen T. dolabrata var. hondai saplings had large photosynthetic production in two seasons, before the emergence of new foliage and after foliage fall of
the overstory deciduous trees, because of the significantly high solar radiant energy penetrating under the forest canopy
during the seasons. Saplings of deciduous Q. mongolica var. grosseserrata were heavily shaded throughout the growing season by foliage of the overstory trees, which resulted in a low daily surplus
production. The annual surplus production of leaves in the growing season was estimated to be 2300 mmol CO 2 m −2 in T. dolabrata var. hondai and −100 mmol CO 2 m −2, slightly negative, in Q. mongolica var. grosseserrata. These results supported the high survivability of T. dolabrata var. hondai saplings and the high mortality of Q. mongolica var. grosseserrata in the deciduous forest. 相似文献
8.
Indole-3-acetic acid-1′- 14C (IAA- 14C) and tryptophan-1- 14C injected in small amounts into cotyledons of Phaseolus coccineus L. seedlings were found to be translocated acropetally into the epicotyls and young shoots. Similarly IAA- 14C was translocated acropetally into coleoptiles of Zea mays following injection into the endosperms. Labeled metabolites of the injected compounds were also extractable from shoot tissue. However, evidence that IAA- 14C itself was translocated acropetally was obtained by collection in agar blocks applied to cut surfaces of coleoptiles of injected seedlings. The acropetal translocation in Phaseolus was shown not to occur in the transpiration stream but in living tissue. Cotyledons of Phaseolus coccineus and Phaseolus vulgaris contain extensive vascular tissue. 相似文献
9.
—The urinary excretion of labelled metabolites was measured in dogs which had been injected intravenously or intraventricularly with [ 3H]norepinephrine or [ 14C]dopamine. [ 3H]Norepinephrine injected by either route produced more labelled 3-methoxy-4-hydroxy-phenylglycol than 3-methoxy-4-hydroxymandelic acid, as did [ 14C]dopamine after intravenous administration. In contrast, following the intraventricular injection of [ 14C]dopamine, more [ 14C]3-methoxy-4-hydroxymandelic acid was formed than [ 14C]3-methoxy-4-hydroxyphenylglycol. These observations suggest that the metabolism of exogenously-administered and endogenously-formed norepinephrine may proceed through different routes and that the predominant metabolite of norepinephrine in canine brain may be 3-methoxy-4-hydroxymandelic acid rather than 3-methoxy-4-hydroxyphenylglycol. 相似文献
10.
At the end of the spring 1987 growing season, the mycoparasite Sporidesmium sclerotivorum was applied at 0, 0.2, 2 or 20 kg ha‐1 to lettuce plants infected with Sclerotinia minor. Disease incidence was monitored in the same plots for five subsequent crops (three fall and two spring crops) without additional application of either pathogen or mycoparasite. Logistic growth curves were fitted to the data to describe disease progression over time for each inoculum level within each of the five crops. Within each crop, increasing the quantity of mycoparasite inoculum resulted in positive horizontal displacement of the curve with respect to time. As quantities of inoculum of S. sclerotivorum increased, inflection points of the disease progress curves increased at a decreasing rate. Thus, additional mycoparasite inoculum resulted in ever‐smaller increases in inflection point, and after a certain threshold level of mycoparasite inoculum ( < 0.2 kg ha‐1), increases in inflection point did not result in meaningful increases in harvestable lettuce. Maximum rates of disease increase were not different among the treatments within each crop, but were different between crops. Maximum rates of disease increase averaged 3.4, 3.4, 2.1, 3.6 and 1.5% day‐1 for the fall 1987, spring 1988, fall 1988, spring 1989, and fall 1989, respectively. At all inoculum levels, the fall epidemics began later after planting than the spring epidemics. 相似文献
11.
Summary The digestion and metabolism of Eucalyptus radiata foliage was studied in a small (1–1.5 kg) arboreal marsupial, the greater glider ( Petauroides volans). Mean dry matter intake was 44 g·kg –0.75·d –1 and mean cell wall digestibility was 34%; these values fall within the range of other marsupials fed Eucalyptus foliage. Digestible energy content of E. radiata was high compared to other eucalypts because of the high content and digestibility of essential oils. However, excretion of essential oils and their metabolites in the urine meant that greater gliders retained only 55% of their digestible energy intakes (0.61 MJ · kg –0.75· d –1) as metabolizable energy (ME). Low ME intakes were not offset by low standard metabolic rates (2.39 W · kg –0.75), but the efficiency with which ME substituted for tissue energy was high (94%), so that greater gliders were able to maintain energy balance and body mass on E. radiata foliage.Abbreviations
ME
metabolizable energy
-
DE
digestible energy
-
RQ
respiratory quotient
-
FHP
fasting heat production 相似文献
12.
A method is described allowing the identification and separation of the sulphate esters of the glycol metabolites of [ 14C]noradrenaline injected into the lateral ventricle of the rat. The esters of both the 3,4-dihydroxy derivative and the 3-methoxy-4-hydroxy derivative are formed in substantial amounts. It is suggested that the quantity of the former may have been underestimated in the past. Contemporaneous administration of pyrogallol, a catechol-O-methyl transferase inhibitor, with [ 14C] noradrenaline leads to a considerable fall in 3-methoxy-4-hydroxyphenylglycol sulphate without a rise in 3-4-dihydroxyphenylglycol sulphate although free 3-4-dihydroxyphenylglycol rises significantly. It is proposed that the latter may be an index of intraneuronal metabolism of noradrenaline and 3-methoxy-4-hydroxyphenylglycol that of released amine. 相似文献
13.
Time-course studies on the distribution and metabolism of valproate (VPA) in rat brain, liver, and kidney, after intraperitoneal injection of a mixture of [ 14C]VPA and [ 3H]VPA, showed that: (1) maximal amount of radioactivity in the various tissues was observed after 30 min from the time the drug was administered; (2) at 30 min the distribution of labeled VPA in brain, liver, and kidney was 17%, 64%, and 19% of the total radioactivity, respectively; (3) at 24 hr more than 97% of the total radioactivity was lost from the tissues and the 14C/ 3H ratios increased significantly with time. Studies on the regional distribution of the drug showed that it is relatively homogeneously distributed. Studies on the subcellular distribution of the drug showed that it is associated mostly with the soluble and mitochondrial fractions, with little radioactivity in the myelin and synaptosomal fractions. Radiochromatography of VPA metabolites in perchloric acid extracts from brain, liver, and kidney revealed the presence of four metabolites. VPA was not incorporated into phospholipids of the neuronal membranes. Furthermore, it had no significant effects on Mg 2+-ATPase and (Na ++K +)-ATPase in synaptosomes and microsomes obtained either from control or from rats injected with VPA. It was concluded that this antiepileptic drug does not appear to act through its incorporation into neuronal membrane or through its action on the Na + pump.Contribution No. 0601 from the Department of Cell and Molecular Biology, the Medical College of Georgia, Augusta, Georgia 30912. 相似文献
14.
The arthropod fauna of 25 saplings and of three conspecific mature trees of Pourouma bicolor (Cecropiaceae) was surveyed for 12 months in a tropical wet forest in Panama, with particular reference to insect herbivores. A construction crane erected at the study site provided access to tree foliage in the upper canopy. A similar area of foliage (ca. 370 m 2) was surveyed from both saplings and trees, but samples obtained from the latter included 3 times as much young foliage as from the former. Arthropods, including herbivores and leaf-chewing insects with a proven ability to feed on the foliage of P. bicolor were 1.6, 2.5 and 2.9 times as abundant on the foliage of trees as on that of saplings. The species richness of herbivores and proven chewers were 1.5 ( n=145 species) and 3.5 ( n=21) times higher on trees than on saplings, respectively. Many herbivore species preferred or were restricted to one or other of the host stages. Host stage and young foliage area in the samples explained 52% of the explained variance in the spatial distribution of herbivore species. Pseudo-replication in the two sampling universes, the saplings and trees studied, most likely decreased the magnitude of differences apparent between host stages in this forest. The higher availability of food resources, such as young foliage, in the canopy than in the understorey, perhaps combined with other factors such as resource quality and enemy-free space, may generate complex gradients of abundance and species richness of insect herbivores in wet closed tropical forests. 相似文献
15.
Heat stable β-exotoxin, purified from fermentations of Bacillus thuringiensis, induced malformed mouthparts in adult cabbage loopers, Trichoplusia ni, when mature larvae were injected with 9 ng β-exotoxin per 280 mg larva. Larvae injected with 26 ng β-exotoxin produced 50% adults with malformed mouthparts. Protein and nucleic acid synthesis was inhibited by presence of β-exotoxin. Specifically, β-exotoxin inhibited in vivo incorporation of 14C-valine, 14C-uracil, and 14C-thymidine into protein, RNA, and DNA, respectively. Percent inhibition, 120 min post-injection of 50 μg β-exotoxin per larva, was 53% (protein), 36% (RNA), and 41% (DNA). The asymptote for inhibition of synthesis was reached ∼30-min after injection of β-exotoxin. 相似文献
16.
The effects of cigarette smoke on the metabolism of exogenous arachidonic acid (AA) were investigated in isolated hamster lungs. Arachidonate was injected into the pulmonary circulation and the metabolites were analysed from the nonrecirculating perfusion effluent by thin layer chromatography. After the pulmonary injection of 66 nmol of 14C-AA about 20 % of the injected radioactivity appreated in the perfusion effluent mostly as metabolites in six minutes. When isolated lungs were ventilated with cigarette smoke during the perfusion, the amounts of PGF 2α, PGE 2 and two unidentified metabolite groups increased in the lung effluent. In two other experimental series hamsters were exposed to cigarette smoke before the lung perfusion either once for 30 min or during one hour daily for ten consecutive days. Neither pre-exposures caused any changes in the amounts of arachidonate metabolites in the lung effluent. 相似文献
17.
dl-[1,6- 14C]Lipoic acid was synthesized and administered to rats or incubated in vitro with rat liver systems. The urinary excretion of radioactivity after labeled lipoate was administered intraperitoneally at a level of 0.5 mg/100 g body weight was maximal at 3–6 hr, with 60% of the injected radioactivity recovered within 24 hr. Respiratory 14CO 2 from the same animals is maximal at 3 hr, after which it falls off markedly. Approximately 30% of the injected radioactivity was recovered as 14CO 2 within 24 hr. The excretion of radioactivity after lipoate was administered by stomach tube was similar to that after intraperitoneal injection. Localization of radioactivity in the body was greatest in liver, intestinal contents, and muscle in all cases. Ionexchange and paper chromatographies of 24-hr pooled urine revealed several watersoluble radioactive metabolites. Incubation of [ 14C]lipoate with homogenates or mitochondrial preparations in vitro resulted in the production of 14CO 2, which was decreased by incubation with unlabeled fatty acids and unaffected by the addition of carnitine or (+)-decanoylcarnitine. The rat, like certain bacteria, metabolizes lipoate via β-oxidation of the valeric acid side chain and by other metabolic reactions on the dithiolane ring, which render the molecule more water soluble. 相似文献
18.
Abstract. - 1 The effect of ponderosa pine (Pinus ponderosa Doug]. ex Laws) water stress, measured by xylem water potential, on oviposition preference and egg development of Neodiprion fulviceps was determined by two laboratory experiments in 1987 and 1988.
- 2 In the first experiment, adult females were allowed to choose between foliage from water-stressed, watered, and untreated control trees.
- 3 Significant differences were found between treatments in xylem water potential in 1987 but not in 1988.
- 4 Females chose water-stressed trees and a positive correlation was found between female preference and xylem water potential in 1987 but not in 1988.
- 5 In the second experiment, females were placed in globe cages with a single branch from each treatment and allowed to oviposit.
- 6 Significant differences were found among treatments in egg survival in 1987 but not in 1988.
- 7 These results indicate that sawflies can distinguish between stressed and non-stressed trees and that this behaviour is adaptive in that egg survival was greatest on the preferred treatment.
相似文献
19.
Summary Rust infected leaves of wheat plants were incubated with glucose- 14C. Uredospores which were formed during the application of the tracer were analyzed. All isolated compounds were labeled with 14C. When germinating uredospores were incubated directly with 14C-glucose, the isolated glutamic acid, arginine and lysine had practically no radioactivity. These compounds did, however, contain considerable 14C-activity when they were isolated from uredospores formed on leaves that had been treated with the tracer. We therefore conclude that these amino acids were synthesized in the host and were taken up by the haustoria of the mycelium.High 14C-radioactivity was also found in all carbohydrates (chitin, glucomannan, polyols etc.). Hexoses isolated from the spore constituents chitin and glucomannan showed the same distribution of radioactivity as the applied glucose-1- 14C or glucose-6- 14C. It follows that the rust mycelium takes up glucose or a similar monosaccharide from the wheat plant. The C-6-skeleton is not degraded to smaller metabolites before it is taken up. 相似文献
20.
When cytokinin 6-(γ,γ-dimethylallylamino)-purine-8- 14C was injected into the side root of a one-year-old apple graft, variety Cox's Orange Pippin, it was mainly transported acropetally, but a certain part of the radioactivity was also transported basipetally into the root below the place of injection. 6 days after application of the labelled cytokinin most of the radioactivity was detected in the xylem, 20–30 cm above the place of application. An appreciable quantity of radioactivity was transported toward the apical part of the plant as far as 100 cm from the point of application. Special analysis showed that 6 days after exposition about half of the remaining radioactivity was present in 6-(γ,γ-dimethylallylamino)-purine-8-C 14 and the rest went to the other metabolites. The cytokinin was transported acropetally mainly in the transpiration stream. 相似文献
|