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81.
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Zusammenfassung
Dendraster laevis bildet ein grünes, wasserlösliches Pigment (farblos bei pH unter 5) und kein Echinochrom.Dendraster excentricus dagegen erzeugt zwei purpurrote, wasserlösliche und zwei echinochromähnliche Pigmente.
Contribution from the Scripps Institution of Oceanography, University of California, New Series No 773. 相似文献
Contribution from the Scripps Institution of Oceanography, University of California, New Series No 773. 相似文献
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Proline isomerism in staphylococcal nuclease characterized by NMR and site-directed mutagenesis 总被引:2,自引:0,他引:2
Nuclear magnetic resonance (NMR) studies have shown that two distinct folded conformations of staphylococcal nuclease coexist in solution and that these two states can interconvert directly without passing through an unfolded state. These experiments have also revealed that the two forms have very different folding kinetics, although the possibility that one component is an obligatory intermediate for the folding of the other form could be discounted. Here we report NMR data which show that alternative unfolded states are also distinguishable. These observations led us to hypothesize that cis/trans isomerism at a single peptide bond between a proline and its preceding residue might be the origin of the conformational multiplicity. Proline 117 was identified as a likely candidate for the site concerned and a mutant protein, in which Pro 117 was replaced by Gly, was constructed in order to test this. Alternative conformations are not observed in the spectrum of this mutant, lending powerful support to this hypothesis. 相似文献
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Soderberg AM Kulkarni SR Berger E Fox DW Sako M Frail DA Gal-Yam A Moon DS Cenko SB Yost SA Phillips MM Persson SE Freedman WL Wyatt P Jayawardhana R Paulson D 《Nature》2004,430(7000):648-650
Over the six years since the discovery of the gamma-ray burst GRB 980425, which was associated with the nearby (distance approximately 40 Mpc) supernova 1998bw, astronomers have debated fiercely the nature of this event. Relative to bursts located at cosmological distance (redshift z approximately 1), GRB 980425 was under-luminous in gamma-rays by three orders of magnitude. Radio calorimetry showed that the explosion was sub-energetic by a factor of 10. Here we report observations of the radio and X-ray afterglow of the recent GRB 031203 (refs 5-7), which has a redshift of z = 0.105. We demonstrate that it too is sub-energetic which, when taken together with the low gamma-ray luminosity, suggests that GRB 031203 is the first cosmic analogue to GRB 980425. We find no evidence that this event was a highly collimated explosion viewed off-axis. Like GRB 980425, GRB 031203 appears to be an intrinsically sub-energetic gamma-ray burst. Such sub-energetic events have faint afterglows. We expect intensive follow-up of faint bursts with smooth gamma-ray light curves (common to both GRB 031203 and 980425) to reveal a large population of such events. 相似文献
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Qiu W Hu M Sridhar A Opeskin K Fox S Shipitsin M Trivett M Thompson ER Ramakrishna M Gorringe KL Polyak K Haviv I Campbell IG 《Nature genetics》2008,40(5):650-655
There is increasing evidence showing that the stromal cells surrounding cancer epithelial cells, rather than being passive bystanders, might have a role in modifying tumor outgrowth. The molecular basis of this aspect of carcinoma etiology is controversial. Some studies have reported a high frequency of genetic aberrations in carcinoma-associated fibroblasts (CAFs), whereas other studies have reported very low or zero mutation rates. Resolution of this contentious area is of critical importance in terms of understanding both the basic biology of cancer as well as the potential clinical implications of CAF somatic alterations. We undertook genome-wide copy number and loss of heterozygosity (LOH) analysis of CAFs derived from breast and ovarian carcinomas using a 500K SNP array platform. Our data show conclusively that LOH and copy number alterations are extremely rare in CAFs and cannot be the basis of the carcinoma-promoting phenotypes of breast and ovarian CAFs. 相似文献
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Cia Ramström Hugh Chapman Tero Viitanen Emad Afrasiabi Heli Fox Johanna Kivelä Sanna Soini Laura Korhonen Dan Lindholm Michael Pasternack Kid Törnquist 《Cellular and molecular life sciences : CMLS》2010,67(1):157-169
The HERG (KCNH2) channel is a voltage-sensitive potassium channel mainly expressed in cardiac tissue, but has also been identified in other tissues like neuronal and smooth muscle tissue, and in various tumours and tumour cell lines. The function of HERG has been extensively studied, but it is still not clear what mechanisms regulate the surface expression of the channel. In the present report, using human embryonic kidney cells stably expressing HERG, we show that diacylglycerol potently inhibits the HERG current. This is mediated by a protein kinase C-evoked endocytosis of the channel protein, and is dependent on the dynein–dynamin complex. The HERG protein was found to be located only in early endosomes and not lysosomes. Thus, diacylglycerol is an important lipid participating in the regulation of HERG surface expression and function. 相似文献