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排序方式: 共有116条查询结果,搜索用时 31 毫秒
81.
G. Andersson E. Hansson C. G. Schmiterlöw 《Cellular and molecular life sciences : CMLS》1965,21(4):211-213
Zusammenfassung Der Übertritt von C14-Nicotin aus der Magenschleimhaut von Mäusen, Ratten und Katzen in den Mageninhalt wurde autoradiographisch und mit Radioaktivitätsmessungen untersucht. Perfusionsversuche des Rattenmagens in situ ergaben eine pH-abhängige Nikotinausscheidung. Chromatographisch wurde die ausgeschiedene Radioaktivität teils im Nikotin selber, teils im Abbauprodukt Cotinin nachgewiesen.
This investigation was supported by grants from Svenska Tobaks AB and the American Medical Association. 相似文献
This investigation was supported by grants from Svenska Tobaks AB and the American Medical Association. 相似文献
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Hessa T Kim H Bihlmaier K Lundin C Boekel J Andersson H Nilsson I White SH von Heijne G 《Nature》2005,433(7024):377-381
Membrane proteins depend on complex translocation machineries for insertion into target membranes. Although it has long been known that an abundance of nonpolar residues in transmembrane helices is the principal criterion for membrane insertion, the specific sequence-coding for transmembrane helices has not been identified. By challenging the endoplasmic reticulum Sec61 translocon with an extensive set of designed polypeptide segments, we have determined the basic features of this code, including a 'biological' hydrophobicity scale. We find that membrane insertion depends strongly on the position of polar residues within transmembrane segments, adding a new dimension to the problem of predicting transmembrane helices from amino acid sequences. Our results indicate that direct protein-lipid interactions are critical during translocon-mediated membrane insertion. 相似文献
85.
Wildermuth S Hofferberth S Lesanovsky I Haller E Andersson LM Groth S Bar-Joseph I Krüger P Schmiedmayer J 《Nature》2005,435(7041):440
Today's magnetic-field sensors are not capable of making measurements with both high spatial resolution and good field sensitivity. For example, magnetic force microscopy allows the investigation of magnetic structures with a spatial resolution in the nanometre range, but with low sensitivity, whereas SQUIDs and atomic magnetometers enable extremely sensitive magnetic-field measurements to be made, but at low resolution. Here we use one-dimensional Bose-Einstein condensates in a microscopic field-imaging technique that combines high spatial resolution (within 3 micrometres) with high field sensitivity (300 picotesla). 相似文献
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Gudbjartsson DF Thorvaldsson T Kong A Gunnarsson G Ingolfsdottir A 《Nature genetics》2005,37(10):1015-1016
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Loss of acetylation at Lys16 and trimethylation at Lys20 of histone H4 is a common hallmark of human cancer 总被引:25,自引:0,他引:25
Fraga MF Ballestar E Villar-Garea A Boix-Chornet M Espada J Schotta G Bonaldi T Haydon C Ropero S Petrie K Iyer NG Pérez-Rosado A Calvo E Lopez JA Cano A Calasanz MJ Colomer D Piris MA Ahn N Imhof A Caldas C Jenuwein T Esteller M 《Nature genetics》2005,37(4):391-400
CpG island hypermethylation and global genomic hypomethylation are common epigenetic features of cancer cells. Less attention has been focused on histone modifications in cancer cells. We characterized post-translational modifications to histone H4 in a comprehensive panel of normal tissues, cancer cell lines and primary tumors. Using immunodetection, high-performance capillary electrophoresis and mass spectrometry, we found that cancer cells had a loss of monoacetylated and trimethylated forms of histone H4. These changes appeared early and accumulated during the tumorigenic process, as we showed in a mouse model of multistage skin carcinogenesis. The losses occurred predominantly at the acetylated Lys16 and trimethylated Lys20 residues of histone H4 and were associated with the hypomethylation of DNA repetitive sequences, a well-known characteristic of cancer cells. Our data suggest that the global loss of monoacetylation and trimethylation of histone H4 is a common hallmark of human tumor cells. 相似文献
88.
Lateral gene transfer in eukaryotes 总被引:23,自引:0,他引:23
Andersson JO 《Cellular and molecular life sciences : CMLS》2005,62(11):1182-1197
Lateral gene transfer – the transfer of genetic material between species – has been acknowledged as a major mechanism in prokaryotic genome evolution for some time. Recently accumulating data indicate that the process also occurs in the evolution of eukaryotic genomes. However, there are large rate variations between groups of eukaryotes; animals and fungi seem to be largely unaffected, with a few exceptions, while lateral gene transfer frequently occurs in protists with phagotrophic lifestyles, possibly with rates comparable to prokaryotic organisms. Gene transfers often facilitate the acquisition of functions encoded in prokaryotic genomes by eukaryotic organisms, which may enable them to colonize new environments. Transfers between eukaryotes also occur, mainly into larger phagotrophic eukaryotes that ingest eukaryotic cells, but also between plant lineages. These findings have implications for eukaryotic genomic research in general, and studies of the origin and phylogeny of eukaryotes in particular.Received 3 December 2004; received after revision 24 January 2005; accepted 1 February 2005 相似文献
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