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991.
992.
《The Journal of steroid biochemistry and molecular biology》1998,66(5-6):347-353
Hormonal requirements for full hepatic expression of 2-macroglobulin (2M), 1-acid glycoprotein (AGP), haptoglobin (Hp) and γ-fibrinogen (Fb) were assessed at the level of mRNA. Prior to exposure to turpentine-induced inflammation, rats were either depleted of glucocorticoids by adrenalectomy or supplemented with an excess of dexamethasone. Adrenalectomy alone did not affect the basal level of acute phase protein (APP) expression except for 2M mRNA, the level of which was enhanced. In contrast, dexamethasone treatment alone promoted full induction of 2M, significant, but not maximal increase of AGP and Hp mRNAs and suppression of Fb. In adrenalectomized rats, acute phase (AP)-cytokines, released in response to inflammation, promoted full expression of Fb and Hp and increased the level of AGP mRNA whereas 2M mRNA remained at the basal level. Inflammation in dexamethasone pretreated rats elicited changes which, in comparison to mRNA values for dexamethasone unpretreated inflamed rats, were seen as overexpression of 2M, full expression of AGP and incomplete expression of Hp, whereas Fb mRNA remained at the basal level. These data suggest that glucocorticoids are the principal inducers of 2M and AP-cytokines of Fb. For full induction of AGP, additive actions of glucocorticoids and AP-cytokines are required whereas expression of Hp is predominantly controlled by AP-cytokines. 相似文献
993.
994.
Bacterial DNA as immune cell activator 总被引:12,自引:0,他引:12
Pattern recognition receptors of the innate and adaptive immune systems apparently recognize unmethylated CpG motifs of bacterial DNA. Cells of the innate immune system are activated directly by CpG motifs, and the resulting response dictates a Th1 bias to the developing adaptive immune response. Interestingly, antigen receptor occupancy of cells of the adaptive immune system augments their responsiveness to CpG motifs, suggesting that co-stimulatory mechanisms are operative. 相似文献
995.
野生稻光周期反应研究 总被引:5,自引:0,他引:5
对稻属不同种及部分中国普通野生稻的光周期反应进行了比较研究,结果表明供试材料在短日下能量提早抽穗,它们对短日诱导的敏感程度与染色体组有一定关系,AA染色体组的稻种,其光周期反应呈明显的多样性,中国东乡,茶酸,江永,仁化普通野生稻短日性强弱不同,与地理分布有关,即分布纬度较高的类型感光性较弱,另外还对群体内光周期反应差异及苗龄效应也作了研究。 相似文献
996.
997.
We present an individual-based model of a group of foraginganimals. Individuals can obtain food either by discovering itthemselves or by stealing it from others (kleptoparasitism).Given that challenging another individual for a discovered fooditem costs time (which could otherwise be spent searching foran undiscovered item), attempting to steal from another maynot always be efficient We show that there is generally a uniquestrategy that maximizes uptake ratealways or never challengingothers. For any combination of parameter values, we can identifywhich strategy is appropraite. As a corollary to this, we predictthat small changes in ecolgical conditions can, under some circumstances,cause a dramatic change in the aggressive behavior of individuals.Further, we investigate situations where searching for undiscoveredfood and searching for potential opportunities for stealingare mutually exclusive activities (i.e., success at one canonly be improved at the expense of the other). Using game theory,we are able to find the evolutionarily stable strategy for investmentin these two activities in terms of the ecological parametersof the model. 相似文献
998.
999.
1000.
It was investigated that active oxygen species (AOS) involved in the plant defense responses induced by fungal elicitor xylanase.
When xylanase from the fungusTrichoderma viridae was treated to tobacco suspension cultured cells as an elicitor, β-glucanase activity was increased markedly. Lignin biosynthesis
was also increased and peaked at 72 h after the treatment with xylanase. The treatment of H2O2 also dramatically increased β-glucanase activity at 24 h, which was much earlier than that of xylanase did. Using lucigenin-and
luminol-dependent chemiluminescence, the effects of xylanase on oxidative burst were examined. Superoxide anion (O2) production was peaked at 40 h and 52 h after xylanase treatment and hydrogen peroxide (H2O2) release was peaked at 44 h and 56 h, suggesting H2O2 burst was followed by O2 generation. The scavengers of AOS, n-propyl gallate (PG) and mannitol, inhibited xylanase-induced β-glucanase activity by
85% and 50%, respectively. The activity of superoxide dismutase (SOD), which catalyzes the dismutation of O2 to H2O2, began to increase from 24 h and reached to maximum at 48 h after xylanase treatment. Pretreatment of N,N,-diethyldithiocarbamate
(DDC), known as a SOD inhibitor, caused the inhibition of H2O2 generation by 80% and reduced the β-glucanase activity by 60%. Treatment of 2,5-norbonadiene (NBD), a specific ethylene-action
inhibitor, did not have any significant effect on xylanase-induced β-glucanase activity. This result suggested that ethylene
did not involve in xylanase-induced response. Our results strongly suggest that the AOS generation is an essential component
in plant defense response, in which cell wall degrading enzyme, glucanase, contributes to remove the necrotic tissue induced
by pathogens. 相似文献