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Differential activation of myotube nuclei following exposure to an acetylcholine receptor-inducing factor 总被引:11,自引:0,他引:11
A glycoprotein purified from chick brain, of relative molecular mass 42,000, increases the rate of appearance of acetylcholine receptors (AChRs) on the surface of chick myotubes. RNase protection assays have shown that this AChR-inducing activity (ARIA) increases the amount of mRNA encoding the alpha-subunit of the AChR, with little or no effect on the amounts of gamma- and delta-mRNAs2. Here, we report that the mRNAs encoding the alpha- and gamma-subunits of the receptor detected by in situ hybridization are concentrated around nuclei in cultured myotubes. Consistent with previous results, ARIA selectively increased the amount of alpha-subunit mRNA, but we now find that all nuclei were not activated to the same extent, with a substantial number not responding at all. Assuming that ARIA is released by motor nerve terminals, our results indicate that only a subset of muscle nuclei are capable of contributing to the accumulation of AChRs at developing neuromuscular junctions. 相似文献
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Among mycobacteria, Mycobacterium leprae is unique in its ability to oxidize a variety of diphenols to quinones in vitro. What physiologic role o-diphenoloxidase has in the organism remained unknown. Reducing substrates like NADPH, NADH and ascorbic acid reacted with the quinone formed from dopa (3,4-dihydroxyphenylalanine); the substrates were oxidized and the quinone was reduced back to diphenol in the process. Since the quinone undergoes reversible oxidation-reduction, diphenoloxidase might serve as an alternative respiratory mechanism in M. leprae for the utilization of other substrates, as has been reported in plants. 相似文献
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The c-myc oncogene driven by immunoglobulin enhancers induces lymphoid malignancy in transgenic mice 总被引:39,自引:0,他引:39
J M Adams A W Harris C A Pinkert L M Corcoran W S Alexander S Cory R D Palmiter R L Brinster 《Nature》1985,318(6046):533-538
Transgenic mice bearing the cellular myc oncogene coupled to the immunoglobulin mu or kappa enhancer frequently develop a fatal lymphoma within a few months of birth. Since the tumours represent represent both immature and mature B lymphocytes, constitutive c-myc expression appears to be highly leukaemogenic at several stages of B-cell maturation. These myc mice should aid study of lymphoma development, B-cell ontogeny and immunoglobulin regulation. 相似文献
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Summary Two closely related species of Gentianaceae were established in tissue culture and transferred to a regeneration medium containing 2,4-D. Even though the age of cultures and all the environmental conditions were identical, only one of them expressed a clear morphogenic potential, and the differences are expressive in the isozyme banding patterns observed for creatine phosphokinase, lactate dehydrogenase and indoleacetaldehyde dehydrogenase. No differences in alkaline phosphatase isozymes were detected.This work was supported in part by the National Science Foundation (No. DCB 8 611 889) USA with a grant to the senior author. 相似文献
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I. M. Varndell A. Harris F. J. Tapia N. Yanaihara J. De Mey S. R. Bloom J. M. Polak 《Cellular and molecular life sciences : CMLS》1983,39(7):713-717
Summary Gastrin (G)-producing cells from the mammalian gastric antrum have been investigated using computer-assisted morphometry and a novel double colloidal gold-labeled-immunoglobulin electron immunocytochemical procedure. Correlation analysis of human antral G-cells indicates (p<0.001) that a single population of granules exists with small (160 nm) electron-dense and large (240 nm) electron-lucent forms representing the extremes. Non-crossreacting region-specific antisera have been used to visualize G-17 and G-34 (progastrin) to the small electron-dense granules and G-17 to the other intermediate forms. From the results we propose a topographic segregation of immunoreactive gastrins within 2 apparently distinct granule subclasses and suggest that this may represent the pathway of granule maturation. 相似文献
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