排序方式: 共有18条查询结果,搜索用时 15 毫秒
1.
Sayer JA Otto EA O'Toole JF Nurnberg G Kennedy MA Becker C Hennies HC Helou J Attanasio M Fausett BV Utsch B Khanna H Liu Y Drummond I Kawakami I Kusakabe T Tsuda M Ma L Lee H Larson RG Allen SJ Wilkinson CJ Nigg EA Shou C Lillo C Williams DS Hoppe B Kemper MJ Neuhaus T Parisi MA Glass IA Petry M Kispert A Gloy J Ganner A Walz G Zhu X Goldman D Nurnberg P Swaroop A Leroux MR Hildebrandt F 《Nature genetics》2006,38(6):674-681
2.
Bacterial growth and primary production along a north-south transect of the Atlantic Ocean 总被引:3,自引:0,他引:3
The oceanic carbon cycle is mainly determined by the combined activities of bacteria and phytoplankton, but the interdependence of climate, the carbon cycle and the microbes is not well understood. To elucidate this interdependence, we performed high-frequency sampling of sea water along a north-south transect of the Atlantic Ocean. Here we report that the interaction of bacteria and phytoplankton is closely related to the meridional profile of water temperature, a variable directly dependent on climate. Water temperature was positively correlated with the ratio of bacterial production to primary production, and, more strongly, with the ratio of bacterial carbon demand to primary production. In warm latitudes (25 degrees N to 30 degrees S), we observed alternating patches of predominantly heterotrophic and autotrophic community metabolism. The calculated regression lines (for data north and south of the Equator) between temperature and the ratio of bacterial production to primary production give a maximum value for this ratio of 40% in the oligotrophic equatorial regions. Taking into account a bacterial growth efficiency of 30%, the resulting area of net heterotrophy (where the bacterial carbon demand for growth plus respiration exceeds phytoplankton carbon fixation) expands from 8 degrees N (27 degrees C) to 20 degrees S (23 degrees C). This suggests an output of CO2 from parts of the ocean to the atmosphere. 相似文献
3.
LDL-receptor-related protein 6 is a receptor for Dickkopf proteins 总被引:42,自引:0,他引:42
Wnt glycoproteins have been implicated in diverse processes during embryonic patterning in metazoa. They signal through frizzled-type seven-transmembrane-domain receptors to stabilize beta-catenin. Wnt signalling is antagonized by the extracellular Wnt inhibitor dickkopf1 (dkk1), which is a member of a multigene family. dkk1 was initially identified as a head inducer in Xenopus embryos but the mechanism by which it blocks Wnt signalling is unknown. LDL-receptor-related protein 6 (LRP6) is required during Wnt/beta-catenin signalling in Drosophila, Xenopus and mouse, possibly acting as a co-receptor for Wnt. Here we show that LRP6 (ref. 7) is a specific, high-affinity receptor for Dkk1 and Dkk2. Dkk1 blocks LRP6-mediated Wnt/beta-catenin signalling by interacting with domains that are distinct from those required for Wnt/Frizzled interaction. dkk1 and LRP6 interact antagonistically during embryonic head induction in Xenopus where LRP6 promotes the posteriorizing role of Wnt/beta-catenin signalling. Thus, DKKs inhibit Wnt co-receptor function, exemplifying the modulation of LRP signalling by antagonists. 相似文献
4.
Astrid Wichmann Markus Kuhn Kay Hoeksema Ulrich Hoppe 《Cellular and molecular life sciences : CMLS》1992,48(1):1-3
Ethical principles and guidelines for scientific experiments on animals 相似文献
5.
6.
Walter Salvator Contro Johannes Viktor Feitzinger Rolf Hartmann Friedrich W. Ihloff Hans-Georg Märtl Friedemann Rex Matthias Schramm Horst Zehe 《Archive for History of Exact Sciences》1970,6(5):360-371
Zusammenfassung
Copernicus versucht, die Ptolemäischen Konstruktionen auf konzentrische Kreise und Epizykel zu reduzieren und aus ihnen ein wirklich einheitliches System zu schaffen. Bei der Umordnung, die er dazu vornimmt, bemüht er sich aber, so viel wie möglich vom Ptolemäischen System zu erhalten. Das punctum aequans ersetzt er bei den äußeren Planeten durch eine Näherungskonstruktion mit Hilfe eines Epizykels. Im Fall des Ptolemäischen Deferenten der Venus, der nach seinen Vorstellungen die Erdbahn wiedergibt, muß er einen dem punctum aequans annähernd gleichwertigen Epizykelmechanismus auf die Venusbahn verpflanzen.
Vorgelegt von
B. L. van der Waerden 相似文献
7.
8.
9.
W. Hoppe 《Cellular and molecular life sciences : CMLS》1955,11(7):281-282
Summary A new instrument for the U.V. spectrometry of microscopic preparations, which uses quartz objectives not only for magnification, but also for monochromatization, permits measurements up to extinctionsE of more than 2.
Mit Unterstützung der Ciba-Stiftung für chemische, mediziinsche und technische Forschung. 相似文献
Mit Unterstützung der Ciba-Stiftung für chemische, mediziinsche und technische Forschung. 相似文献
10.
R. N. B. Kay P. Hoppe G. M. O. Maloiy 《Cellular and molecular life sciences : CMLS》1976,32(4):485-487
Summary Fermentation of leafy food occurs in the enlarged saccus gastricus of the colobus monkey with the formation of volatile fatty acid, as in the rumen of ruminant animals. About half of the digestible organic matter and cellulose of the diet is digested in this way.We wish to thank the Inter-University Council, the Nuffield Foundation and the Wellcome Trust for financial support. MrP. J. S. Dewey kindly made the determinations of cellulose and lignin. 相似文献