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21.
Relative importance of the effect of 2,4-D,glyphosate, and environmental variables on the soil microbial biomass 总被引:2,自引:0,他引:2
Two post-emergence herbicides (glyphosate and 2,4-D) were applied at field application levels to tilled field plots in a mixed cropping area in south-central Alberta. The effects of these chemicals on certain variables associated with microbial biomass and activity were monitored in these plots (as well as corresponding control plots) for 45 days. Glyphosate did not influence any of the microbial variables tested. Addition of 2,4-D significantly influenced all microbial variables investigated but these effects were transient, being detectable only within the first 1–5 days of herbicide addition. The effects of 2,4-D addition on the microbial variables tested, even when significant, were typically small and probably of little ecological consequence especially when spatial and temporal variation in these variables is taken into account. 相似文献
22.
High-level expression of a tobacco chitinase gene in Nicotiana sylvestris. Susceptibility of transgenic plants to Cercospora nicotianae infection 总被引:12,自引:0,他引:12
Jean-Marc Neuhaus Patricia Ahl-Goy Ursula Hinz Susan Flores Frederick Meins Jr. 《Plant molecular biology》1991,16(1):141-151
Endochitinases (E.C. 3.2.14, chitinase) are believed to be important in the biochemical defense of plants against chitin-containing fungal pathogens. We introduced a gene for class I (basic) tobacco chitinase regulated by Cauliflower Mosaic Virus 35S-RNA expression signals into Nicotiana sylvestris. The gene was expressed to give mature, enzymatically active chitinase targeted to the intracellular compartment of leaves. Most transformants accumulated extremely high levels of chitinase-up to 120-fold that of non-transformed plants in comparable tissues. Unexpectedly, some transformants exhibited chitinase levels lower than in non-transformed plants suggesting that the transgene inhibited expression of the homologous host gene. Progeny tests indicate this effect is not permanent. High levels of chitinase in transformants did not substantially increase resistance to the chitin-containing fungus Cercospora nicotiana, which causes Frog Eye disease. Therefore class I chitinase does not appear to be the limiting factor in the defense reaction to this pathogen. 相似文献
23.
24.
The life stages ofEntomophaga grylli (Fresenius) Batko Pathotype 2 were purified and separated by centrifugation in PercollR density-gradient medium. The ranges of buoyant densities for germinated resting spores, germ conidia, and resting spores
respectively were: 1.040–1.050, 1.055–1.085, and 1.080–1.120 g/ml. Cuticular invasion by germinated germ conidia was the means
by whichMelanoplus grasshoppers became infected. Scanning electron micrographs revealed germination of germ conidia on the visible host integument
at 100% RH, but not at 90% RH. Significantly higher mortality (P<0.05) was obtained after 3 weeks with grasshoppers incubated
in constant light than in constant dark for 24 h following treatment. The disease was not transmitted by ingestion of any
life stage.
Contribution No 85-153-J, Department of Entomology. Agricultural Experiment Station, Kansas State University, Manhattan, KS 66506. 相似文献
25.
INTERNAL SPREAD OF FUNGI INOCULATED 总被引:3,自引:3,他引:0
26.
Type I protein kinase C isozyme in the visual-information-processing pathway of monkey brain 总被引:1,自引:0,他引:1
F L Huang Y Yoshida H Nakabayashi D P Friedman L G Ungerleider W S Young K P Huang 《Journal of cellular biochemistry》1989,39(4):401-410
Previously using PKC isozyme-specific antibodies for immunoblot analysis, we demonstrated the heterogeneous distribution of PKC isozymes in various regions of monkey and rat brains and that type I PKC was most abundant in cerebellum, hippocampus, amygdala, and cerebral cortex (Huang et al.: J Biol Chem 262:15714-15720, 1987). Using these antibodies, we have also demonstrated that type I, II, and III PKC are products of PKC genes gamma, beta, and alpha, respectively (Huang et al.: Biochem Biophys Res Commun 149:946-952, 1987). By immunocytochemical analysis, type I PKC-specific antibody showed strong reactivity in various types of neuron in hippocampal formation, amygdala, cerebellum, and neocortex. In hippocampal formation, granule cells of dentate gyrus and pyramidal cells of hippocampus were heavily stained. By immunoblot analysis, relative levels of PKC isozymes in several areas of monkey cerebral cortex involved in the visual information processing and storage were determined. Both type II and III PKCs appeared to be evenly distributed and at moderate levels, type I PKC formed a gradient of increasing concentration rostral along the cerebral cortex of occipital to temporal and then to the limbic areas. Neurobehavioral studies have demonstrated that the neocortical and limbic areas of the anterior and medial temporal regions participate more directly than the striate, prestriate, and posterior temporal regions in the storage of visual representations and that both hippocampus and amygdala are important in the memory formation. As type I PKC is present at high levels in hippocampus, amygdala, and anterior temporal lobe, we predict that the type I protein kinase C may participate in the plastic changes important for mnemonic function. 相似文献
27.
Arachidonic acid, cellulase, CuSO4, a sonicate of Phytophthora infestans mycelium and a spore suspension of Penicillium chrysogenum all elicited the formation of the sesquiterpenoid phytoalexins lubimin, 3-hydroxylubimin and rishitin in fruit cavities of Datura stramonium. 3-Hydroxylubimin was the predominant phytoalexin formed after treatment of the fruits with arachidonic acid, cellulase and the P. infestans preparation. Copper sulphate was a potent elicitor of lubimin but not 3-hydroxylubimin. The fungus P. chrysogenum metabolized lubimin and 3-hydroxylubimin to 15-dihydrolubimin and 3-hydroxy-15-dihydrolubimin respectively, both in fruit cavities inoculated with spores of this fungus and in pure culture. The 15-dihydrolubimin formed in the fruits by the fungus was further metabolized (by the fruits) to both isolubimin and 3-hydroxy-15-dihydrolubimin. The precursor-product relationships between all of the subject compounds was investigated by feeding experiments with 3H-labelled compounds. 2-Dehydro-[15-3H1]lubimin was rapidly and efficiently incorporated into lubimin and may be the direct precursor of lubimin in planta. 3-Hydroxy[2-3H1]lubimin was incorporated into the nor-eudesmane rishitin but 10-epi-3-hydroxy[2-3H1]lubimin was not. An updated scheme for the biosynthesis and metabolism of lubimin and related compounds in infected tissues of solanaceous plants is presented.We thank Mr Vic Swetez for the provision of plant material, Mrs Margaret Huffee for technical assistance, Dr David Ewing for help with obtaining NMR spectra, and the Agricultural and Food Research Council for financial support. 相似文献
28.
Three post-emergence herbicides (2,4-D, picloram and glyphosate) were applied to samples of an Alberta agricultural soil at
concentrations of 0, 2, 20, and 200 μg g−1. The effects of these chemicals on certain microbial variables was monitored over 27 days. All herbicides caused enhancement
of basal respiration but only for 9 days following application, and only for concentrations of 200 μg g−1. Substrate-induced respiration was temporarily depressed by 200 μg g−1 picloram and 2,4-D, and briefly enhanced by 200 μg g−1 glyphosate. It is concluded that because changes in microbial variables only occurred at herbicide concentrations of much
higher than that which occurs following field application, the side-effects of these chemicals is probably of little ecological
significance. 相似文献
29.
Cell-suspension cultures of two chickpea (Cicer arietinum L.) cultivars, resistant (ILC 3279) and susceptible (ILC 1929) to the fungus Ascochyta rabiei (Pass.) Lab., showed differential accumulation of the phytoalexins medicarpin and maackiain, and transient induction of related enzyme activities after application of an A. rabiei-derived elicitor. The chalcone-synthase (CHS) activity (EC 2.3.1.74) which is involved in the first part of phytoalexin biosynthesis exhibited a maximum 8–12 h after elicitation in the cells of both cultivars. Concomitant with the fivefold-higher phytoalexin accumulation, CHS activity increased twofold in the cells of the resistant cultivar. The maximum of the elicitor-induced CHS-mRNA activity was determined 4 h after onset of induction in the cultures of both cultivars, although in cells of cultivar ILC 3279 this mRNA activity was induced at a level twofold higher than that in cells of the susceptible race ILC 1929. Investigations of CHS isoenzymes by two-dimensional gel electrophoresis of immunoprecipitated in-vitro-translated protein indicated the presence of five proteins. In the cells of both cultivars only two of the isoenzymes were induced after elicitor treatment. Analysis of the total in-vitro-translated proteins by two-dimensional gel electrophoresis showed that the constitutively expressed patterns of mRNA activities in the cell cultures of the two cultivars were identical. After elicitation, considerably more translatable mRNAs were induced in the cells of cultivar ILC 3279. The few induced proteins, and their respective mRNA activities, which could be detected in the cells of the susceptible cultivar, all existed in the cells of the resistant cultivar, too. One highly induced protein (Mr 18 kDa) found in the cells of cultivar ILC 3279 reached its maximum mRNA activity 6 h after elicitor application. The amount of this protein was hardly increased in the cells of the susceptible cultivar. This protein appears to be excreted from the cells into the growth medium.Abbreviations CHS
chalcone synthase
- IEF
isoelectric focussing
- ILC
international legume chickpea
- PR-protein
pathogenesis-related protein
- SDS-PAGE
sodium dodecyl sulfate-polyacrylamide gel electrophoresis
Financial support by Deutsche Forschungsgemeinschaft and Fonds der Chemischen Industrie is gratefully acknowledged. The authors thank Dr. K. Hahlbrock (Max-Planck-Institut für Züchtungsforschung, Köln, FRG) for provision of antisera and the International Centre for Agricultural Research in the Dry Areas (Aleppo, Syria) for plant material. 相似文献
30.
Time-Dependent Increase in Protein Phosphorylation Following One-Trial Enhancement in Hermissenda 总被引:1,自引:1,他引:0
Abstract: One-trial conditioning of the nudibranch mollusk Hermissenda produces short- and long-term changes in excitability (enhancement) of identified sensory neurons. To investigate the biochemical mechanisms underlying this example of plasticity, we have examined changes in protein phosphorylation at different times following the in vitro conditioning trial. Changes in the incorporation of 32 PO4 into proteins were determined using two-dimensional polyacrylamide gel electrophoresis, autoradiography, and densitometry. Conditioning resulted in increases in levels of several phosphoproteins, five of which, ranging in apparent molecular mass from 22 to 55 kDa, were chosen for analysis. The increased phosphorylation of the 46- and 55-kDa phosphoproteins detected 2 h postconditioning was significantly greater than the level of phosphorylation detected in an unpaired control group, indicating that long-term enhancement is pairing specific. Statistically significant increases in phosphorylation as compared with the control group that received only light were detected immediately after conditioning (5 min) for the 55-, 46-, and 22-kDa phosphoproteins, at 1 h for the 55- and 46-kDa phosphoproteins, and at 2 h for the 55-, 46-, and 22-kDa phosphoproteins. The 46- and 55-kDa phosphoproteins are putative structural proteins, and the 22-kDa phosphoprotein is proposed to be a protein kinase C substrate previously identified in Hermissenda following multitrial classical conditioning. Time-dependent increases in protein phosphorylation may contribute to the induction and maintenance of different memory stages expressed in sensory neurons after one-trial conditioning. 相似文献