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921.
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Zheng Tan Na Xie Sami Banerjee Huachun Cui Mingui Fu Victor J. Thannickal Gang Liu 《The Journal of biological chemistry》2015,290(1):46-55
There has been fast growing evidence showing that glycolysis plays a critical role in the activation of immune cells. Enhanced glycolysis leads to increased formation of intracellular lactate that is exported to the extracellular environment by monocarboxylate transporter 4 (MCT4). Although the biological activities of extracellular lactate have been well studied, it is less understood how the lactate export is regulated or whether lactate export affects glycolysis during inflammatory activation. In this study, we found that MCT4 is up-regulated by TLR2 and TLR4, but not TLR3 agonists in a variety of macrophages. The increased expression of MCT4 was mediated by MYD88 in a NF-κB-dependent manner. Furthermore, we found that MCT4 is required for macrophage activation upon TLR2 and TLR4 stimulations, as evidenced by attenuated expression of proinflammatory mediators in macrophages with MCT4 knockdown. Mechanistically, we found that MCT4 knockdown leads to enhanced intracellular accumulation of lactate and decreased glycolysis in LPS-treated macrophages. We found that LPS-induced expression of key glycolytic enzymes hexokinase 2 and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 is diminished in macrophages with MCT4 knockdown. Our data suggest that MCT4 up-regulation represents a positive feedback mechanism in macrophages to maintain a high glycolytic rate that is essential to a fully activated inflammatory response. 相似文献
923.
The relative roles of genetics and developmental plasticity in creating phenotypes adapted to prevailing conditions are insufficiently understood. In potentially multivoltine temperate insects, individuals that do not enter diapause but develop directly into reproductive adults within the same season are severely time-constrained. Direct development is, however, under selection only if expressed in the wild. Thus, adaptive correlates of the direct development are expected to evolve and persist only in multivoltine populations. We studied the genetic and phenotypic components of variation in juvenile development in the geometrid moth Chiasmia clathrata from univoltine and bivoltine regions. Larvae were reared at two temperatures (14/20 °C) and densities (low/high) in a factorial split-brood experiment. High temperature and low density promoted direct development, the former condition being associated with a short development time, high growth rate and large body size. Genotypes of bivoltine origin had a higher propensity for direct development and seemingly expressed an exaggerated plastic response to increasing temperature compared to the ones from univoltine populations. Alternative life history phenotypes associated with the induced developmental pathway emerged only in the bivoltine region, direct development resulting in a short larval period, high growth rate and small size at 20 °C there. The degree of differentiation between the developmental pathways was insensitive to larval density; high density only decreased both development time and body size to a certain degree. We conclude that the differences between the pathways are not due to the induction of a particular pathway itself, but geographically varying selection pressures shape the correlation structure among life history traits and their pathway-specific expression. 相似文献
924.
We propose a novel plant-based amphiphilic diblock co-oligomers (BCO) surfactant containing only carbohydrate segments and examine its potential as a biosourced stabilizer. The synthesis of an amphiphilic xyloglucan-based BCO, composed of a hydrophilic xyloglucan oligosaccharide (XGO) block “clicked” to a hydrophobic peracetylated XGO is described. Dynamic light scattering experiments correlated with transmission electron microscopy observations showed that this new class of amphiphilic BCO self-assembles in water to form spherical micelles with a hydrodynamic diameter of 22 nm. Preliminary studies indicate that the XGO-based BCO sterically stabilizes gliadin and zein nanoparticle suspensions. The stabilization results were compared to those using pluronic F-68, a commercial surfactant. For gliadin nanoparticles, both surfactants result in essentially the same morphology and polydispersity. However, for the zein nanoparticles, the XGO-based BCO stabilizer gave lower polydispersity. 相似文献
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928.
Sami Ahmad Chris A. Pritsos Ronald S. Pardini 《Archives of insect biochemistry and physiology》1990,15(2):101-109
The black swallowtail butterfly, Papilio polyxenes, larvae are specialized feeders of pro-oxidant rich plants of Apiaceae and Rutaceae. An important defense against toxic forms of oxygen species generated by ingestion of the pro-oxidants, are the antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), GSH-dependent glutathione peroxidases (selenium-dependent glutathione peroxidase [GPOX] and peroxidase activity of selenium-independent glutathione-S-transferase [GTpx]), and glutathione reductase (GR). The subcellular distribution of these enzymes in black swallowtail larvae was investigated and was found to resemble the patterns described for larvae of two other lepidopteran species: the southern armyworm, Spodoptera eridania, and the cabbage looper, Trichoplusia ni. The confinement of SOD in the cytosol and mitochondria was typically eukaryotic, but the relative proportion (1:1) was markedly different from the mammalian pattern (4:1; cytosol:mitochondria). The most obvious difference between the black swallowtail and other lepidoptera as a group, and mammalian species, is in very wide intracellular distributions of CAT, GTpx, and GR in insect species. Insects possess very low levels of a GPOX-like activity which reduces both H2O2 and organic peroxides. Consequently, insects have elaborate activities with a wide subcellular distribution of both CAT which decomposes H2O2, and GTpx which decomposes organic peroxides. The reduction of peroxides is dependent on GSH, which in this process is oxidized to GSSG. GR which reduces GSSG to GSH is also of wide subcellular distribution, analogous to the distribution pattern of GTpx. 相似文献
929.
Ethnologists have the opportunity to document the dynamics of domestication, particularly the cognitive aspects of that process, which archeologists are unable to reconstruct. In this article we show how the recent intensification of cultivation, accompanied by genetic alteration, of a basketry fiber plant, Proboscidea parviflora subspecies parviflora, among the O'odham (Pima) has been accompanied by shifts in the structure of O'odham folk taxonomy. The emic focus on specific plant characteristics, codified in this changing lexicon, may guide cultural selection and encourage isolation of incipient domesticates from their wild progenitors. 相似文献
930.