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51.
Metamorphic core complexes are domal uplifts of metamorphic and plutonic rocks bounded by shear zones that separate them from unmetamorphosed cover rocks. Interpretations of how these features form are varied and controversial, and include models involving extension on low-angle normal faults, plutonic intrusions and flexural rotation of initially high-angle normal faults. The D'Entrecasteaux islands of Papua New Guinea are actively forming metamorphic core complexes located within a continental rift that laterally evolves to sea-floor spreading. The continental rifting is recent (since approximately 6 Myr ago), seismogenic and occurring at a rapid rate ( approximately 25 mm yr-1). Here we present evidence-based on isostatic modelling, geological data and heat-flow measurements-that the D'Entrecasteaux core complexes accommodate extension through the vertical extrusion of ductile lower-crust material, driven by a crustal density inversion. Although buoyant extrusion is accentuated in this region by the geological structure present-which consists of dense ophiolite overlaying less-dense continental crust-this mechanism may be generally applicable to regions where thermal expansion lowers crustal density with depth. 相似文献
52.
Labelled depolarizing drugs in normal and denervated muscle 总被引:2,自引:0,他引:2
53.
Summary Incubation in solutions containing high potassium levels reduces specific accumulation of cyclic AMP in larval nerve cords ofManduca, sexta in vitro with or without serotonin or theophylline.Supported in part by NIH grant NS-09161-20 to R.W.N. 相似文献
54.
Summary This new triangulation technique allows the investigator to make cross-measurements of individual cells quickly and easily with a high degree of accuracy and reliability. 相似文献
55.
Primary structure of Torpedo californica acetylcholinesterase deduced from its cDNA sequence 总被引:11,自引:0,他引:11
M Schumacher S Camp Y Maulet M Newton K MacPhee-Quigley S S Taylor T Friedmann P Taylor 《Nature》1986,319(6052):407-409
Acetylcholinesterase, an essential enzyme of the nervous system, rapidly terminates the action of acetylcholine released into the synapse. Acetylcholinesterase is also found (in lower abundance) in extrajunctional areas of muscle and nerve and on erythrocyte membranes. Hydrodynamic analyses of the native enzyme and characterization of its dissociated subunits have revealed multiple enzyme forms which can be divided into two classes: dimensionally asymmetric forms which are usually found within the synapse and contain a collagen-like structural subunit disulphide-linked to the catalytic subunits; and globular forms which appear to be widely distributed on the outer surface of cell membranes. Both forms have been characterized in the ray Torpedo californica and, although their catalytic behaviours seem to be identical, they differ slightly in amino-acid composition, peptide maps and reactivity with certain monoclonal antibodies. Here, we report the complete amino-acid sequence of an acetylcholinesterase inferred from the sequence of a complementary DNA clone. The 575-residue protein shows significant homology with the C-terminal portion of thyroglobulin. 相似文献
56.
Summary The cerebral insufficiency improvers centrophenoxine, piracetam and hydergine were tested for their effect on lipid peroxidation of rat brain homogenates, both in vitro and in vivo. There was no effect either in vitro or after chronic 8 week dosing of animals. 相似文献
57.
W. C. Eisenberg K. Taylor L. J. Schiff 《Cellular and molecular life sciences : CMLS》1984,40(5):514-515
Summary Exposure of hamster tracheal organ cultures to gas phase singlet delta oxygen,1O2, at atmospheric pressure produced significant alterations in the mucociliary epithelium resulting in changes in ciliary activity and cellular morphology.Acknowledgments. The authors acknowledge helpful conversations with Professor R.W. Murray of the University of Missouri (St. Louis). We would like to thank the National Institute of Environmental Health Sciences for supporting this work through Public Health Grant 1-RO1-ESO1-O1A1-PHTB. 相似文献
58.
59.
Schistosome vaccines 总被引:2,自引:0,他引:2
D. W. Taylor 《Cellular and molecular life sciences : CMLS》1991,47(2):152-157
Summary Schistosomiasis control currently relies primarily on chemotherapy which is both expensive and temporary. There is an urgent need for an effective vaccine. Studies in animal models and man have demonstrated the existence of protective immunity. Antibody-dependent cell-mediated cytotoxicity mechanisms involving eosinophils and macrophages have been implemented in destruction of the parasites. Antigens expressed on the surface of the schistosomulum are among the targets of protective immune responses. Vaccines comprising recombinant antigens are now being tested in vivo for their capacity to evoke protective responses. Live oral vaccines based on attenuatedSalmonella expressing schistosomular surface antigens are being developed. 相似文献
60.