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991.
The pH dependence of the spectra and of the oxidation-reduction potential of three cytochromes c2, from Rhodopseudomonas capsulata, Rhodopseudomonas sphaeroides and Rhodomicrobium vannielii, were studied. A single alkaline pK was observed for the spectral changes in all three ferricytochromes. In Rps. capsulata cytochrome c2 this spectroscopic pK corresponds to the pK observed in the dependence of oxidation-reduction potential on pH. For the other two cytochromes the oxidation-reduction potential showed a complex dependency on pH which can be fitted to theoretical curves involving three ionizations. The third ionization corresponds to the ionization observed in the spectroscopic studies but the first two occur without changes in the visible spectra.The possible structural bases for these ionizations are discussed. 相似文献
992.
Christopher Yau Dmitri Mouradov Robert N Jorissen Stefano Colella Ghazala Mirza Graham Steers Adrian Harris Jiannis Ragoussis Oliver Sieber Christopher C Holmes 《Genome biology》2010,11(9):R92
We describe a statistical method for the characterization of genomic aberrations in single nucleotide polymorphism microarray
data acquired from cancer genomes. Our approach allows us to model the joint effect of polyploidy, normal DNA contamination
and intra-tumour heterogeneity within a single unified Bayesian framework. We demonstrate the efficacy of our method on numerous
datasets including laboratory generated mixtures of normal-cancer cell lines and real primary tumours. 相似文献
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994.
In vitro fertilization of mouse ova by spermatozoa exposed isothermally to radio-frequency radiation
Mouse spermatozoa were exposed in vitro for 1 h to 27- or 2,450-MHz CW RF radiation at SARs of 0 to 90 W/kg under isothermal (37 +/- 0.2 degrees C) conditions. Exposure at either frequency to RF radiation at SARs of 50 W/kg or greater resulted in a statistically significant reduction in the ability of irradiated sperm to fertilize mouse ova in vitro (P less than .05). Over the range of SARs there was no apparent difference in the effects of 27- vs. 2,450-MHz RF radiation. There were no readily detectable exposure effects on spermatozoan morphology, ultrastructure, or capacitation. The reduction of in vitro fertilization is attributed to a direct effect of RF radiation on spermatozoa rather than to heating. 相似文献
995.
Transport of zinc and manganese to developing wheat grains 总被引:11,自引:0,他引:11
An understanding of the transport pathway used by Zn and Mn to enter developing grains may allow measures to increase the Zn and Mn content of wheat grain grown on Zn/Mn deficient soils. For this reason, transport of Zn and Mn into developing grains of wheat ( Triticum aestivum L. cv. Aroona) was investigated. Detached ears (18–22 days post-anthesis) were cultured for 48 h in a solution containing 185 kBq of 65 Zn and 185 kBq of 54 Mn. Transport of 65 Zn to the grain was unaffected by removal of glumes but was slightly reduced after the lemma was removed. Heat girdling the peduncle slightly reduced the amount of 65 Zn transported to the grain, whilst heat girdling the rachilla reduced transport of 65 Zn to the grain to a greater degree, suggesting phloem transport to the rachilla. The transport inhibitor CCCP (carbonyl cyanide m -chlorophenyl hydrazone) blocked 65 Zn transport to grain but not to lemma and glumes. Removing glumes and lemma and heat girdling the peduncle did not affect transport of 54 Mn, but transport was slightly affected by heat girdling the rachilla, indicating xylem transport. CCCP blocked transport of 54 Mn into the grain but not to lemma and glumes. It was concluded that xylem-to-phloem transfer of Zn occurs in the rachis and to a lesser extent in peduncle and lemma. The results suggest that the lemma may be an important site for phloem loading when the concentration of Zn within the xylem is high. The data also suggest that Mn was predominantly translocated to the spikelets in the xylem, but that transport to the grain was dependent upon membrane transport before entering the grain. Phloem loading of Mn into the grain vascular system may have occurred at the site of xylem discontinuity in the floral axis. 相似文献
996.
In a review of the records of 74 patients who had undergone repair of an abdominal aortic aneurysm at a community hospital between 1977 and 1983 we found that the aneurysm had been undiagnosed before rupture in 35%; these patients had an operative death rate of 50%, whereas elective repair carried a death rate of 4%. The characteristic patient was an obese man over the age of 55 years with hypertension, coronary artery disease, cerebrovascular disease or peripheral vascular disease. Ultrasound examination was performed in 45 patients with these characteristics, and six aneurysms were diagnosed. Either surgery or computed tomography confirmed the diagnosis. The rate of false-negative results was estimated by review of the charts of 100 men over the age of 55 years who had undergone abdominal ultrasonography for other indications: no undetected aneurysms were discovered over 3 years of follow-up. Routine screening in this high-risk group would improve the rate of diagnosis of this potentially fatal condition before rupture and offer the patient the lower mortality rate associated with elective surgery. 相似文献
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