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31.
Mammalian target of rapamycin (mTOR) signaling is one of the main signaling pathways controlling protein synthesis. Leucine treatment upregulates mTOR signaling, which enhances protein synthesis; however, the mechanisms are not well understood. Herein, treatment of C2C12 myoblast cells with leucine enhanced the phosphorylation of mTOR and ribosomal protein S6 kinase. Leucine treatment also decreased the adenosine monophosphate/ATP ratio in myoblasts by 36.4 +/- 9.1% (P < 0.05) and reduced the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) alpha subunit at Thr172 (28.6 +/- 4.9% reduction, P < 0.05) and inhibited AMPK activity (43.6 +/- 3.5% reduction, P < 0.05). In addition, leucine increased the phosphorylation of mTOR at Ser2448 by 63.5 +/- 10.0% (P < 0.05) and protein synthesis by 30.6 +/- 6.1% (P < 0.05). Applying 5-aminoimidazole-4-carbox-amide 1-beta-d-ribonucleoside, an activator of AMPK, abolished the stimulation of mTOR signaling by leucine, showing that AMPK negatively controls mTOR signaling. To further show the role of AMPK in mTOR signaling, myoblasts expressing a dominant negative AMPKalpha subunit were employed. Negative myoblasts had very low AMPK activity. The activation of mTOR induced by leucine in these cells was abated, showing that AMPK contributed to mTOR activation. In conclusion, leucine stimulates mTOR signaling in part through AMPK inhibition. This study implicates AMPK as an important target for nutritional management to enhance mTOR signaling and protein synthesis in muscle cells, thereby increasing muscle growth. 相似文献
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QTL mapping of resistance in lentil (Lens culinaris ssp. culinaris) to ascochyta blight (Ascochyta lentis) 总被引:1,自引:0,他引:1
Quantitative trait locus (QTL) analysis of ascochyta blight resistance in lentil was conducted using genomic maps developed from two F2 populations, viz. ILL5588/ILL7537 and ILL7537/ILL6002. Five QTLs for ascochyta blight resistance were identified by composite interval mapping (CIM) across four linkage groups (LG) in population ILL5588/ILL7537. Three QTLs were identified by CIM in population ILL7537/ILL6002 (two in close proximity on LGI and one on LGII). Two of these coincided with regions identified using multiple interval mapping (MIM) and were shown to be conditioned by dominant and partial dominant gene action. Together, they accounted for approximately 50% of the phenotypic variance of disease severity. Comparison between the two populations revealed a potentially common QTL and several common regions that contained markers significantly associated with resistance. This study demonstrated the transferability of QTLs among populations and identified markers closely linked to the major QTL that may be useful for future marker‐assisted selection for disease resistance. 相似文献
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Abstract: The border studies literature makes a strong case against claims for unfettered transnationalism and ‘borderlessness’ in our ‘globalising world’. However, its focus on movement across borders means that it fails to address bordering practices that occur within the nation‐state as a result of transnational activity. In this paper, we extend Cunningham and Heyman’s concepts ‘enclosure’ and ‘mobility’ to confront the different layers of bordering (both physical and non‐physical) that have occurred in Indonesia’s Riau Islands since they became part of the Indonesia–Malaysia–Singapore Growth Triangle. 相似文献
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Our experience in developing models to predict the potential impacts of oil spills on colonially breeding marine birds has revealed some major gaps in the information available on these systems. We consider the availability of data for a variety of parameters of seabird biology that are required in modelling efforts, and assign provisional priorities to our information needs. In order to develop means of predicting the impacts of oil spills on seabirds, we suggest that colony- or site-specific information on the timing of reproduction and colony occupancy, chick growth rates and body weights, several metabolic parameters, flight speed, and food load size is of relatively low overall priority. Intermediate priority is assigned to the collection of specific data on the dynamics of oil spills, the age and breeding structure of the populations, reproductive success, foraging activity budgets and flight paths, flight costs, and the response of growing chicks to food deprivation. We suggest that studies of seabird biology should give highest priority to obtaining information on population sizes, the probability of adult death upon encountering a spill, age-specific fecundity and survivorship, the time required in foraging trips, the lag time in the response of birds to an oil spill, foraging rate as a function of resource density, and changes in the availability of resources to the birds as a consequence of oil spills. 相似文献
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Pettengill GH Ford PG Brown WE Kaula WM Keller CH Masursky H McGill GE 《Science (New York, N.Y.)》1979,203(4382):806-808
Altimetry and radar scattering data for Venus, obtained from 10 of the first 13 orbits of the Pioneer Venus orbiter, have disclosed what appears to be a rift valley having vertical relief of up to 7 kilometers, as well as a neighboring, gently rolling plain. Planetary oblateness appears unlikely to exceed 1/2500 and may be substantially smaller. 相似文献
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An assemblage of cellularly well-preserved, filamentous and spheroidal plant microfossils has been detected in a cherty pisolite bed of the late Precambrian Chuar Group from the eastern Grand Canyon of the Colorado River. This newly discovered microflora, probably among the youngest Precambrian biological communities now known, appears to be of both evolutionary and biostratigraphic significance. 相似文献