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541.
M G Currie D M Geller B R Cole N R Siegel K F Fok S P Adams S R Eubanks G R Galluppi P Needleman 《Science (New York, N.Y.)》1984,223(4631):67-69
Mammalian cardiac atria have several biologically active peptides that exert profound effects on sodium excretion, urine volume, and smooth muscle tone. In the present study two such peptides of low molecular weight were purified and separated from each other on the basis of differences in charge, hydrophobicity, and biological profile. The first peptide, designated atriopeptin I, exhibits natriuretic and diuretic activity and selectivity relaxes intestinal smooth muscle but not vascular smooth muscle strips. The second peptide, atriopeptin II, is a potent natriuretic and diuretic that relaxes both intestinal and vascular strips. Sequence analysis of atriopeptin I indicates that it is composed of 21 amino acids, of which serine and glycine residues predominate. The amino terminal sequence of atriopeptin II up to residue 21 is the same as that of atriopeptin I, with the addition of the Phe-Arg extension at the carboxyl terminus. Both peptides appear to be derived from a common high molecular weight precursor (designated atriopeptigen); their biological selectivity and potency may be determined by the site of carboxyl terminal cleavage. 相似文献
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545.
Johnson D Krsek M Wellington EM Stott AW Cole L Bardgett RD Read DJ Leake JR 《Science (New York, N.Y.)》2005,309(5737):1047
Annual carbon flux through soil respiration is ten times greater than fossil fuel combustion, but its component parts are poorly understood because they are the product of complex multitrophic interactions between soil organisms. A major component of carbon flux from plants to soil occurs through networks of symbiotic arbuscular mycorrhizal fungi. Here, using 13CO2 pulse labeling, we show that natural densities of the numerically dominant fungal feeding invertebrate Protaphorura armata (order Collembola) reduces 13C enrichment of mycorrhizosphere respiration by 32%. Our findings emphasize the importance of multitrophic interactions in regulating respiration of recent plant photosynthate from soil. 相似文献
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Innis MA Holland MJ McCabe PC Cole GE Wittman VP Tal R Watt KW Gelfand DH Holland JP Meade JH 《Science (New York, N.Y.)》1985,228(4695):21-26
A strain of Saccharomyces cerevisiae capable of simultaneous hydrolysis and fermentation of highly polymerized starch oligosaccharides was constructed. The Aspergillus awamori glucoamylase enzyme, form GAI, was expressed in Saccharomyces cerevisiae by means of the promoter and termination regions from a yeast enolase gene. Yeast transformed with plasmids containing an intron-free recombinant glucoamylase gene efficiently secreted glucoamylase into the medium, permitting growth of the transformants on starch as the sole carbon source. The natural leader sequence of the precursor of glucoamylase (preglucoamylase) was processed correctly by yeast, and the secreted enzyme was glycosylated through both N- and O-linkages at levels comparable to the native Aspergillus enzyme. The data provide evidence for the utility of yeast as an organism for the production, glycosylation, and secretion of heterologous proteins. 相似文献
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Hess SL Henry RM Leovy CB Ryan JA Tillman JE Chamberlain TE Cole HL Dutton RG Greene GC Simon WE Mitchell JL 《Science (New York, N.Y.)》1976,193(4255):788-791
The results from the meteorology instruments on the Viking 1 lander are presented for the first 4 sols of operation. The instruments are working satisfactorily. Temperatures fluctuated from a low of 188 degrees K to an estimated maximum of 244 degrees K. The mean pressure is 7.65 millibars with a diurnal variation of amplitude 0.1 millibar. Wind speeds averaged over several minutes have ranged from essentially calm to 9 meters per second. Wind directions have exhibited a remarkable regularity which may be associated with nocturnal downslope winds and gravitational oscillations, or to tidal effects of the diurnal pressure wave, or to both. 相似文献
550.
R. H. True A. F. Reeves R. V. Akeley H. J. Murphy G. A. Porter R. H. Cole J. Watts B. J. Christ F. E. Manzer 《American Journal of Potato Research》1990,67(3):153-161
The Somerset potato variety is a medium-maturing variety with attractive, round to oblong, white-skinned, white-fleshed tubers with shallow eyes. Its major use is expected to be as a chipping variety in areas where potatoes are stored for some length of time, since its sugar content is lower than most varieties during storage, and it can be chipped after six months in storage. Somerset does not show the net necrosis caused by potato leafroll virus, and is immune to race 0 of Phytophthora infestans (late blight). Somerset is also moderately resistant to infection by Alternaria solani (early blight), and is only moderately susceptible to Verticillium wilt. Somerset is more susceptible to both common and acid scab than Superior, but less susceptible than Kennebec and Katahdin. It also has shown susceptibility to skinning and shatter bruise, but does not have a strong blackspot bruise reaction. 相似文献