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161.
WUShi-jing GONGZhi-bo YINYong HUANGHe-chao LOUWei-hua 《武汉大学学报:自然科学英文版》2004,9(5):839-844
Making use of Microsoft Visual Studio. NET platform, hierarchical network planning is realized in working procedure time-optimization of the construction by TBM. and hierarchical network graph of the construction by TBM is drawn based on browser. Then the theory of system realization is discussed, six components of system that can be reused are explained emphatically. The realization of hierarchical network panning in Internet provides available guarantee for controlling rate of progress in large-scale or middle-sized projects. 相似文献
162.
Spampinato S Di Toro R Alessandri M Murari G 《Cellular and molecular life sciences : CMLS》2002,59(12):2172-2183
In this study, we examined agonist-induced internalization, recycling and signalling (measure of cAMP levels) of the cloned human nociceptin receptor (hNOP) expressed in CHO-K1 cells. Internalization was proven by a receptor-binding assay on viable cells. The agonist nociceptin/orphanin FQ (NC) promoted rapid internalization of the hNOP receptor (approximately 78% of cell surface receptors were lost after 2 min exposure to 1 microM NC) in a clathrin- and ATP-dependent manner. Internalization was more rapid and marked in CHO-K1 cells than, as we previously reported, in SK-N-BE cells. This difference may be related to higher levels of beta-arrestin isoforms detected in CHO-K1 than in SK-N-BE cells. hNOP receptor internalization was partially reversible and recycling occurred in the presence of the agonist; receptor recycling was dependent on okadaic acid-sensitive phosphatases and was blocked by monensin. Confocal microscopy analysis confirmed the internalization and the recycling back to the plasma membrane of an epitope-tagged hNOP receptor expressed in CHO-K1 cells. These receptors underwent rapid desensitization upon agonist challenge: NC efficacy in inhibiting forskolin-stimulated cAMP production was significantly reduced 10 min after exposure and correlated with the rate of receptor internalization. Moreover, we observed that blockade of hNOP receptor recycling by monensin would cause a more prolonged and relevant desensitization of this receptor. Thus, the dynamic cycle between hNOP receptor activation, internalization and recycling determines the activity of this receptor on the cell surface. 相似文献
163.
Increasing dominance of large lianas in Amazonian forests 总被引:1,自引:0,他引:1
Phillips OL Vásquez Martínez R Arroyo L Baker TR Killeen T Lewis SL Malhi Y Monteagudo Mendoza A Neill D Núñez Vargas P Alexiades M Cerón C Di Fiore A Erwin T Jardim A Palacios W Saldias M Vinceti B 《Nature》2002,418(6899):770-774
Ecological orthodoxy suggests that old-growth forests should be close to dynamic equilibrium, but this view has been challenged by recent findings that neotropical forests are accumulating carbon and biomass, possibly in response to the increasing atmospheric concentrations of carbon dioxide. However, it is unclear whether the recent increase in tree biomass has been accompanied by a shift in community composition. Such changes could reduce or enhance the carbon storage potential of old-growth forests in the long term. Here we show that non-fragmented Amazon forests are experiencing a concerted increase in the density, basal area and mean size of woody climbing plants (lianas). Over the last two decades of the twentieth century the dominance of large lianas relative to trees has increased by 1.7-4.6% a year. Lianas enhance tree mortality and suppress tree growth, so their rapid increase implies that the tropical terrestrial carbon sink may shut down sooner than current models suggest. Predictions of future tropical carbon fluxes will need to account for the changing composition and dynamics of supposedly undisturbed forests. 相似文献
164.
Calcineurin (CN) is thought to play a role in the synaptic plastivity and long-term potentiation (LTP) in the hippocampus.
Based on two LTP models in vivo, a specific inhibitor cyclosporin A (CsA) of CN was observed, which affected LTP in the hippocampal dentate gyrus of the
rats. The results indicated that CsA blocked LTP induced by high frequency stimulation (HFS) partly, but it had no effect
on the decrease of the onset and peak latency of population spikes (PS) except that it reduced the increase of the amplitude
after HFS. On the other hand, CsA blocked LTP induced by ginsenosides (GSS) completely. It suppressed the GSS-enhanced amplitude
of PS reversibly and blocked the decrease of the peak latency of PS induced by the GSS. These results suggest that the postsynaptic
CN plays a role in the induction of LTP in the hippocampus of the rats. 相似文献
165.
Forkhead-homology-associated (FHA) domains function as protein-protein modules that recognize phosphorylated serine/threonine motifs. Interactions between FHA domains and phosphorylated proteins are thought to have essential roles in the transduction of DNA damage signals; however, it is unclear how FHA-domain-containing proteins participate in mammalian DNA damage responses. Here we report that a FHA-domain-containing protein-mediator of DNA damage checkpoint protein 1 (MDC1; previously known as KIAA0170)--is involved in DNA damage responses. MDC1 localizes to sites of DNA breaks and associates with CHK2 after DNA damage. This association is mediated by the MDC1 FHA domain and the phosphorylated Thr 68 of CHK2. Furthermore, MDC1 is phosphorylated in an ATM/CHK2-dependent manner after DNA damage, suggesting that MDC1 may function in the ATM-CHK2 pathway. Consistent with this hypothesis, suppression of MDC1 expression results in defective S-phase checkpoint and reduced apoptosis in response to DNA damage, which can be restored by the expression of wild-type MDC1 but not MDC1 with a deleted FHA domain. Suppression of MDC1 expression results in decreased p53 stabilization in response to DNA damage. These results suggest that MDC1 is recruited through its FHA domain to the activated CHK2, and has a critical role in CHK2-mediated DNA damage responses. 相似文献
166.
Lou Qin |jian Sarem Mu dar Li Rui |xuan Xiao Wei |jun Lu Zheng |ding Chen Chuan |bo School of Computer Science Technology Huazhong University of Science Technology Wuhan Hubei China 《武汉大学学报:自然科学英文版》2003,8(1):21-27
0 IntroductionTheneedforintegrationofdifferentdatabasemanagementsystems (DBMSs) ,makingdifferencesbetweenthesesystemsinvisibleandprovidinguserswithauniformaccesstoallthedatabaseshasgrownrapidlyduringthelastdecade .However,databaseautonomyandheterogeneity… 相似文献
167.
Hermann H De Petrocellis L Bisogno T Schiano Moriello A Lutz B Di Marzo V 《Cellular and molecular life sciences : CMLS》2003,60(3):607-616
Cannabinoid CB1 receptors and vanilloid VR1 receptors are co-localized to some extent in sensory neurons of the spinal cord and dorsal root ganglia. In this study, we over-expressed both receptor types in human embryonic kidney (HEK)-293 cells and investigated the effect of the CB1 agonist HU-210 on the VR1-mediated increase in intracellular Ca2+ ([Ca2+]i), a well-known response of the prototypical VR1 agonist capsaicin. After a 5-min pre-treatment, HU-210 (0.1 microM) significantly enhanced the effect of several concentrations of capsaicin on [Ca2+]i in HEK-293 cells over-expressing both rat CB1 and human VR1 (CB1-VR1-HEK cells), but not in cells over-expressing only human VR1 (VR1-HEK cells). This effect was blocked by the CB1 receptor antagonist SR141716A (0.5 microM), and by phosphoinositide-3-kinase and phospholipase C inhibitors. The endogenous agonist of CB1 and VR1 receptors, anandamide, was more efficacious in inducing a VR1-mediated stimulation of [Ca2+]i in CB1-VR1-HEK cells than in VR1-HEK cells, and part of its effect on the former cells was blocked by SR141716A (0.5 microM). Pre-treatment of CB1-VR1-HEK cells with forskolin, an adenylate cyclase activator, enhanced the capsaicin effect on [Ca2+]i. HU-210, which in the same cells inhibits forskolin-induced enhancement of cAMP levels, blocked the stimulatory effect of forskolin on capsaicin. Our data suggest that in cells co-expressing both CB1 and VR1 receptors, pre-treatment with CB1 agonists inhibits or stimulates VR1 gating by capsaicin depending on whether or not cAMP-mediated signalling has been concomitantly activated. 相似文献
168.
Involvement of nitric oxide in the signal transduction of salicylic acid regulating stomatal movement 总被引:6,自引:0,他引:6
LIUXin ZHANGShuqiu LOUChenghou 《科学通报(英文版)》2003,48(5):449-452
The effects and the relationship between sali-cylic acid(SA)and nitric oxide(NO) on Vicia faba L.stomatal movement were studied.The results here showed that exogenous SA and NO induced stomatal closure,100μmol/L SA induced a rapid and striking NO increase in the cytosol of guard cells.This phenomenon was largely prevented by 2000μmol/L 2-phenyl-4,4,5,5-tetramethylimidazoline-l-oxyl-3-oxide(PTIO),a specific NO scavenger,and 25μmol/L N^G-nitro-L-Arg-methyl eater (L-NAME),an inhibitor of NO synthase(NOS) in mammalian cells that also inhibits plant NOS.In addition,SA-induced stomatal closure was largely prevented by PTIO and L-NAME.These results provide evidence that guard cells generate NO in response to SA via NOS-like activity,and that such NO production is required for full stomatal closure in response to SA.H-(1,2,4)-oxadiazole-[4,3-α]quinoxalin-l-one(ODQ),an inhibitor of guanylate cyclase,and nicotinamide,an antagonist of cADPR production,inhibited the effects of SA-and NO-induced stomatal closure.It suggests that both cGMP and cADPR might mediate the signal transduction of SA and NO-induced stomatal closure. 相似文献
169.
Family change, when adults depart or arrive around children, raises policy issues. Its measurement depends upon the evidence collected and from whom. This paper compares British children's histories obtained from fathers and mothers. The evidence, on one birth cohort of parents, comes from two sources: the National Child Development Study and the ONS Longitudinal Study. The resulting account of family change is not substantially different between parents. There is some under-reporting of children not living with their fathers. This is due to under-reporting by those included in the studies and to under-representation in them of absent fathers and lone parents. 相似文献
170.
一个有限半群是满足左正则性条件的IC富足半群当且仅当它是一个幂等元形成左正则带的纯整超富足半群,但满足左正则性条件的无限IC富足半群不都是幂等元形成左正则带的纯整超富足半群. 相似文献