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排序方式: 共有101条查询结果,搜索用时 15 毫秒
1.
The detection of apple chlorotic leafspot virus by a modified procedure of enzyme-linked immunosorbent assay (ELISA) 总被引:1,自引:0,他引:1
The technique of enzyme-linked immunosorbent assay (ELISA) was modified to enable detection of apple chlorotic leafspot virus (CLSV) both in herbaceous hosts and in several naturally infected fruiting and ornamental woody host species. Some of the characteristics of the modified method as used with different virus-host combinations are described. 相似文献
2.
THALER M.; STEIGNER W.; F?RSTER B.; K?HLER K.; SIMONIS W.; URBACH W. 《Journal of experimental botany》1989,40(11):1195-1203
The role of cytoplasmic calcium activity in activation of K+-channelsin the unicellular green alga Eremosphaera viridis has beenstudied. As reported previously, after a light offsignal a voltage independent opening of K+-channels in the plasmalemmais observed. This effect is indicated by a transient polarization(TP) with a simultaneous increase of the membrane conductance.TPs can also be triggered by different treatments, which allowinvestigations within a short-circuited signalchain. (i) After incubation with EGTA a single extended TP canbe released by a sudden increase of the external calcium concentration.The Ca2+-channel inhibitors nifedipine (10 2 mol m3)and verapamil (5 ? 102 mol m3) suppress the releaseof this TP. (ii) In the presence of external calcium the additionof the ionophore A23187
[GenBank] (103 mol m3) causes anextremely prolonged TP. (iii) Low external concentrations ofbarium (102 mol m3) induce repetitive TPs in thepresence of external calcium. In this case the Ca2+-channelinhibitors are less effective. (iv) Strontium (0.11.0mol m3) is able to trigger repetitive TPs even withoutexternal calcium. Whereas barium may stimulate a calcium influx,strontium can serve as a substitute for calcium to induce anopening of K+-channels. These results indicate strongly a Ca2+-dependentand voltage-independent activation of K+-channels in the plasmalemmaof Eremosphaera. The participation of cytoplasmic calcium inthe signal transduction chain after a light offsignal is discussed. Key words: Ca2+-dependent K+-channels, Ca2+-channel effectors, A23187, transient membrane potential, Eremosphaera 相似文献
3.
SALLY LYMAN ALLEN JULIAN ADAMS CAROLINE L. RUSHFORD 《The Journal of eukaryotic microbiology》1983,30(1):143-147
ABSTRACT. Up to five zones of acid phosphatase activity appear in gels after electrophoresis of detergent-treated extracts from 13 of the 14 species of the Paramecium aurelia complex. The overall pattern is somewhat similar for all species: differences in intensity and mobility of individual zones permit the grouping of these sibling species into eight groups. All 14 species can be identified using the procedure of enzyme electrophoresis, although two of them are more similar than is usually the case. Problems of misclassification are discussed in terms of the nature and frequency of variants. With the judicious choice of enzymes used to screen new stocks, these problems can be circumvented. Species relationships are updated using 11 enzymes. A dendrogram constructed from the matrix of genetic distances shows four clusters of species: (i) P. biaurelia, P. triaurelia; (ii) P. primaurelia, P. pentaurelia, P. sexaurelia, P. novaurelia; (iii) P. septaurelia, P. undecaurelia, P. tredecaurelia, P. quadecaurelia; and (iv) P. tetraurelia, P. octaurelia, P. decaurelia, P. dodecaurelia. Distances between the species are large, on the order of the differences between Drosophila species. The species are characterized by an extraordinary lack of geographical differentiation and great morphological similarity, which contrasts strongly with the molecular differentiation. 相似文献
4.
- 1 Six 800-sweep samples of English and Michigan (“old field”) secondary vegetation arthropods are compared with Costa Rican samples taken in the same way.
- 2 Parasitic Hymenoptera and spiders accounted for a larger proportion of the arthropod fauna in the mid-latitude than the tropical samples.
- 3 In one English field, the seasonal change in insect numbers was 88% of that recorded over all the seasonal and elevational changes examined in Costa Rica. Furthermore, the difference in the total dry weights of the arthropod fauna between December and July was similar to the difference found between the wet and dry seasons in tropical secondary vegetation (also similar to the difference between day and night values during the dry season).
- 4 Aphids and Psyllidae were far more abundant in the English site than in the Costa Rican mainland sites.
- 5 In mid-summer, the English field had far more arthropods in it than did any of the tropical sites sampled.
5.
CAROLINE S. CHABOO † CHRISTOPHER G. BROWN DANIEL J. FUNK 《Zoological Journal of the Linnean Society》2008,152(2):315-351
Constructions composed of faeces are rare in insects, but occur in certain leaf-beetle clades. Members of the subfamily Cryptocephalinae share a complex behavioural and morphological synapomorphy, involving portable faecal cases that house the immature stages. A maternally initiated egg case is expanded and enlarged through four larval stadia, then sealed to provide a pupal chamber from which adults eventually emerge. We analyse and compare faecal-case architecture in ten taxa of the cryptocephaline genus Neochlamisus , and assess structural variation within a life cycle, between different 'host forms' of Neochlamisus bebbianae , and among species. These cases proved to be comprised primarily of faeces, with plant trichomes representing the only common secondary component. General architectural trends reflected variation in shape, faecal texture, and the incorporation and density of trichomes. Deviations of the Neochlamisus case from a simple geometrical gnomon reflect the changing body size of the animal, differential application of faeces, and shifts in the orientation of the carriage of the case. Neochlamisus cases are presumably energetically costly to produce, carry, and maintain, and some adaptive hypotheses of case evolution are proposed. Additionally, literature on case morphology in other camptosomates is reviewed. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society , 2008, 152 , 315–351. 相似文献
6.
ROBERT NDONG MIREILLE MONTREJAUD-VIGNOLES†‡ OLIVIER SAINT GIRONS BENOÎT GABRIELLE§ ROLAND PIROT¶ MARJORIE DOMERGUE¶ CAROLINE SABLAYROLLES†‡ 《Global Change Biology Bioenergy》2009,1(3):197-210
In recent years, liquid biofuels for transport have benefited from significant political support due to their potential role in curbing climate change and reducing our dependence on fossil fuels. They may also participate to rural development by providing new markets for agricultural production. However, the growth of energy crops has raised concerns due to their high consumption of conventional fuels, fertilizers and pesticides, their impacts on ecosystems and their competition for arable land with food crops. Low-input species such as Jatropha curcas , a perennial, inedible crop well adapted to semiarid regions, has received much interest as a new alternative for biofuel production, minimizing adverse effects on the environment and food supply. Here, we used life-cycle assessment to quantify the benefits of J. curcas biofuel production in West Africa in terms of greenhouse gas emissions and fossil energy use, compared with fossil diesel fuel and other biofuels. Biodiesel from J. curcas has a much higher performance than current biofuels, relative to oil-derived diesel fuels. Under West Africa conditions, J. curcas biodiesel allows a 72% saving in greenhouse gas emissions compared with conventional diesel fuel, and its energy yield (the ratio of biodiesel energy output to fossil energy input) is 4.7. J. curcas production studied is eco-compatible for the impacts under consideration and fits into the context of sustainable development. 相似文献
7.
8.
PHILLIP A. WACKYM CAROLINE T. CHEN AKIRA ISHIYAMA ROBERT M. PETTIS IVN A. L
PEZ LARRY HOFFMAN 《Cell biology international》1996,20(3):187-192
The expression of the five muscarinic acetylcholine receptor (mAChR) subtypes (m1–m5) in the vestibular end-organs and in the primary afferent vestibular ganglia of the human and rat was studied using RT-PCR from the two tissue populations from both species. In the human, although all five mAChR subtypes were expressed in brain, only the m1, m2, and m5 mAChR subtypes were amplified from both the vestibular ganglia and the vestibular end-organs, while in the rat, all five mAChR subtypes were expressed. These data suggest that the efferent cholinergic axo-dendritic and axo-somatic synapses have a muscarinic component and that there are pharmacologic implications for patients with vestibular dysfunction. 相似文献
9.
Delineation of the European Armillaria species based on the sequences of the internal transcribed spacer (ITS) of ribosomal DNA 总被引:1,自引:0,他引:1
MOHAMMED CHILLALI DANIEL WIPF JEAN-JACQUES GUILLAUMIN CAROLINE MOHAMMED & BERNARD BOTTON 《The New phytologist》1998,138(3):553-561
Variation within the internal transcribed spacer (ITS) of the ribosomal RNA gene of 15 isolates representing seven European Armillaria species, was examined by sequencing of the PCR-amplified products. The analysis of an 744-bp region showed that the 5.8S gene appeared to be highly conserved in the 15 isolates and in other Basidiomycetes and Ascomycetes, whereas ITS1 and especially ITS2 spacers exhibited polymorphisms due to base substitutions, insertions or deletions of up to eight nucleotides. An initial dendrogram for the full sequence was drawn using cluster analysis (UPGMA), and a tree was constructed using the maximum parsimony method. Both methods indicated that the isolates could be divided into four major groups. One group, consisting of A. ectypa , was distinct from all the other species. Examination of the other groups indicated that A. tabescens and A. mellea were in a separated cluster, with a significant variation between the two isolates of the latter species. A. gallica and A. cepistipes constituted another closely related group distinguishable from A. ostoyae and A. borealis , these latter two species exhibiting the highest similarity. The results are consistent with, and discussed in regard to, the relationships estimated previously by pairing tests, morphological and physiological comparisons, as well as by restriction fragment length polymorphism of the rDNA. 相似文献
10.
Abstract: A bryozoan fauna from carbonate mud-mounds is described from subsurface well cores from the Upper Ordovician (Lower Ashgill) Jifarah (Djeffara) Formation of Tripolitania, north-west Libya. Among a diverse assemblage dominated by trepostomes, nine species of bryozoans are identified, including Jifarahpora libyensis gen. et sp. nov. Delicate and robust branching, encrusting and nodular bryozoan growth forms are all common. The bryozoan-rich limestones are mostly mudstones and wackestones, with bafflestone and floatstone textures, but the mounds apparently lack organic framework and microbial fabrics. Regional geophysical data indicate rapid thickness changes between wells, where mound complexes locally up to 100 m thick had limited topographic relief over the surrounding sea floor. The mounds formed in a high-latitude, cool-water carbonate belt that extended widely across the northern margin of Gondwana. Quaternary analogues from the Great Australian Bight suggest that these early Ashgill mounds may have developed in slope environments during an episode of glacial lowstand that preceded the late Ashgill, Hirnantian glacial event. 相似文献