排序方式: 共有46条查询结果,搜索用时 15 毫秒
41.
M. Miyashita 《复旦学报(自然科学版)》2005,44(5):781-782
The zoanthamine alkaloids, a type of heptacyclic marine alkaloid lsotateo from colonial zoanthids of the genus Zoanthus sp. , have attracted much attention from a wide area of science, because of their distinctive biological and pharmacological properties as well as their chemical structures with stereochemical complexity. Namely, norzoanthamine (1) can suppress the loss of bone weight and strength in ovariectomized mice and has been considered a promising candidate for an antiosteoporotic drug, whereas zoanthamine (2) has exhibited potent inhibitory activity toward phorbol myristate-induced inflammation in addition to powerful analgesic effects See Fig. 1. 相似文献
42.
Determination of left-right patterning of the mouse embryo by artificial nodal flow 总被引:18,自引:0,他引:18
Substantial insight has recently been achieved into the mechanisms responsible for the generation of left-right (L-R) asymmetry in the vertebrate body plan. However, the mechanism that underlies the initial breaking of symmetry has remained unclear. In the mouse, a leftward fluid flow on the ventral side of the node caused by the vortical motion of cilia (referred to as nodal flow) is implicated in symmetry breaking, but direct evidence for the role of this flow has been lacking. Here we describe the development of a system in which mouse embryos are cultured under an artificial fluid flow and with which we have examined how flow affects L-R patterning. An artificial rightward flow that was sufficiently rapid to reverse the intrinsic leftward nodal flow resulted in reversal of situs in wild-type embryos. The artificial flow was also able to direct the situs of mutant mouse embryos with immotile cilia. These results provide the first direct evidence for the role of mechanical fluid flow in L-R patterning. 相似文献
43.
Lee C Hong B Choi JM Kim Y Watanabe S Ishimi Y Enomoto T Tada S Kim Y Cho Y 《Nature》2004,430(7002):913-917
To maintain chromosome stability in eukaryotic cells, replication origins must be licensed by loading mini-chromosome maintenance (MCM2-7) complexes once and only once per cell cycle. This licensing control is achieved through the activities of geminin and cyclin-dependent kinases. Geminin binds tightly to Cdt1, an essential component of the replication licensing system, and prevents the inappropriate reinitiation of replication on an already fired origin. The inhibitory effect of geminin is thought to prevent the interaction between Cdt1 and the MCM helicase. Here we describe the crystal structure of the mouse geminin-Cdt1 complex using tGeminin (residues 79-157, truncated geminin) and tCdt1 (residues 172-368, truncated Cdt1). The amino-terminal region of a coiled-coil dimer of tGeminin interacts with both N-terminal and carboxy-terminal parts of tCdt1. The primary interface relies on the steric complementarity between the tGeminin dimer and the hydrophobic face of the two short N-terminal helices of tCdt1 and, in particular, Pro 181, Ala 182, Tyr 183, Phe 186 and Leu 189. The crystal structure, in conjunction with our biochemical data, indicates that the N-terminal region of tGeminin might be required to anchor tCdt1, and the C-terminal region of tGeminin prevents access of the MCM complex to tCdt1 through steric hindrance. 相似文献
44.
In this paper based on the experiment principle of evaluating adhesion property by scratch testing, the peeling mechanism of thin films is discussed by applying contact theory and surface physics theory. A mathematical model predicting the critical load is proposed for calculating critical load as determined byscratch testing. The factors for correctly evaluating adhesion of coatings according to the experimental data arediscussed. 相似文献
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46.
Dec1 and Dec2 are regulators of the mammalian molecular clock 总被引:23,自引:0,他引:23
Honma S Kawamoto T Takagi Y Fujimoto K Sato F Noshiro M Kato Y Honma K 《Nature》2002,419(6909):841-844