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41.
42.
Insulin signaling regulates lifespan, reproduction, metabolic homeostasis, and resistance to stress in the adult organism.
In Drosophila, there are seven insulin-like peptides (DILP1–7). Three of these (DILP2, 3 and 5) are produced in median neurosecretory cells
of the brain, designated IPCs. Previous work has suggested that production or release of DILPs in IPCs can be regulated by
a factor secreted from the fat body as well as by neuronal GABA or short neuropeptide F. There is also evidence that serotonergic
neurons may regulate IPCs. Here, we investigated mechanisms by which serotonin may regulate the IPCs. We show that the IPCs
in adult flies express the 5-HT1A, but not the 5-HT1B or 5-HT7 receptors, and that processes of serotonergic neurons impinge on the IPC branches. Knockdown of 5-HT1A in IPCs by targeted RNA interference (RNAi) leads to increased sensitivity to heat, prolonged recovery after cold knockdown
and decreased resistance to starvation. Lipid metabolism is also affected, but no effect on growth was seen. Furthermore,
we show that DILP2-immunolevels in IPCs increase after 5-HT1A knockdown; this is accentuated by starvation. Heterozygous 5-HT1A mutant flies display the same phenotype in all assays, as seen after targeted 5-HT1A RNAi, and flies fed the 5-HT1A antagonist WAY100635 display reduced lifespan at starvation. Our findings suggest that serotonin acts on brain IPCs via the
5-HT1A receptor, thereby affecting their activity and probably insulin signaling. Thus, we have identified a second inhibitory pathway
regulating IPC activity in the Drosophila brain. 相似文献
43.
Shankar Sankaran Bob Dick Kelly Shaw Colleen Cartwright Alan Davies Jacqueline Kelly Barb Vindin 《Systemic Practice and Action Research》2014,27(6):551-573
This article illustrates how scenario planning (SP) and scenario analysis as can be conceptualised as practices contributing to an action research (AR) investigation of leadership development. The project described in this article was intended to strengthen leadership capacity in Australia’s rapidly changing aged care and community care sector. A research team comprising academics from three universities and managers from two faith-based not-for-profit organisations providing aged and community care participated in this study. As part of the research, two sets of scenario-based workshops were held: the first, to identify possible futures using SP; and the second, to deal with plausible scenarios these organisations are likely to face with the changes happening in the aged care environment in Australia by using scenario analysis. Although the researchers did not consider a link between practice theory and AR during the SP phase, practice theory became useful during the scenario analysis phase. The article includes a brief literature review followed by a discussion on the relationship between AR and practice theory. The processes used in the two sets of scenario workshops are then described in detail along with the data collected and analysed. The article concludes with some reflections on the use of scenarios in practice as well as an acknowledgment that practice theory would be useful in investigating leadership capability development. 相似文献
44.
Spinal cord injuries often occur at the cervical level above the phrenic motor pools, which innervate the diaphragm. The effects of impaired breathing are a leading cause of death from spinal cord injuries, underscoring the importance of developing strategies to restore respiratory activity. Here we show that, after cervical spinal cord injury, the expression of chondroitin sulphate proteoglycans (CSPGs) associated with the perineuronal net (PNN) is upregulated around the phrenic motor neurons. Digestion of these potently inhibitory extracellular matrix molecules with chondroitinase ABC (denoted ChABC) could, by itself, promote the plasticity of tracts that were spared and restore limited activity to the paralysed diaphragm. However, when combined with a peripheral nerve autograft, ChABC treatment resulted in lengthy regeneration of serotonin-containing axons and other bulbospinal fibres and remarkable recovery of diaphragmatic function. After recovery and initial transection of the graft bridge, there was an unusual, overall increase in tonic electromyographic activity of the diaphragm, suggesting that considerable remodelling of the spinal cord circuitry occurs after regeneration. This increase was followed by complete elimination of the restored activity, proving that regeneration is crucial for the return of function. Overall, these experiments present a way to markedly restore the function of a single muscle after debilitating trauma to the central nervous system, through both promoting the plasticity of spared tracts and regenerating essential pathways. 相似文献
45.
46.
Michael P. Clements Philip Hans Franses Jeremy Smith Dick van Dijk 《Journal of forecasting》2003,22(5):359-375
We compare linear autoregressive (AR) models and self‐exciting threshold autoregressive (SETAR) models in terms of their point forecast performance, and their ability to characterize the uncertainty surrounding those forecasts, i.e. interval or density forecasts. A two‐regime SETAR process is used as the data‐generating process in an extensive set of Monte Carlo simulations, and we consider the discriminatory power of recently developed methods of forecast evaluation for different degrees of non‐linearity. We find that the interval and density evaluation methods are unlikely to show the linear model to be deficient on samples of the size typical for macroeconomic data. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
47.
给出了利用单片机及TM8880双音多频(DTMF)编、解码电路构成的智能控制系统,这套系统能够通过电话网提供交互式远程控制。 相似文献
48.
49.
Magmatic and amagmatic seafloor generation at the ultraslow-spreading Gakkel ridge,Arctic Ocean 总被引:5,自引:0,他引:5
Michael PJ Langmuir CH Dick HJ Snow JE Goldstein SL Graham DW Lehnert K Kurras G Jokat W Mühe R Edmonds HN 《Nature》2003,423(6943):956-961
A high-resolution mapping and sampling study of the Gakkel ridge was accomplished during an international ice-breaker expedition to the high Arctic and North Pole in summer 2001. For this slowest-spreading endmember of the global mid-ocean-ridge system, predictions were that magmatism should progressively diminish as the spreading rate decreases along the ridge, and that hydrothermal activity should be rare. Instead, it was found that magmatic variations are irregular, and that hydrothermal activity is abundant. A 300-kilometre-long central amagmatic zone, where mantle peridotites are emplaced directly in the ridge axis, lies between abundant, continuous volcanism in the west, and large, widely spaced volcanic centres in the east. These observations demonstrate that the extent of mantle melting is not a simple function of spreading rate: mantle temperatures at depth or mantle chemistry (or both) must vary significantly along-axis. Highly punctuated volcanism in the absence of ridge offsets suggests that first-order ridge segmentation is controlled by mantle processes of melting and melt segregation. The strong focusing of magmatic activity coupled with faulting may account for the unexpectedly high levels of hydrothermal activity observed. 相似文献
50.
H2-receptors in peripheral blood vessels 总被引:2,自引:0,他引:2