Author Keywords: Heat protection; cycloheximide; puromycin; putrescine; spermidine; spermine 相似文献
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71.
脂质过氧化对人红细胞膜脂流动性的影响 总被引:20,自引:3,他引:17
研究枯稀过氧化氢/高铁血红素体系所产生的烷基过氧自由基对红细胞的损伤。测定了脂质过氧化的产物——丙二脂的生成,并证明阿魏酸钠对脂质过氧化的抑制。荧光偏振的结果指出,膜脂过氧化以后降低了膜脂的流动性。人红细胞用5DSA和16DSA标记并用ESR检测膜脂流动性,结果表明,序参数S几乎没有发生变化,旋转相关时间τ值的增加证明膜脂过氧化以后,疏水尾部的物理状态发生了改变。经脂质过氧化以后,红细胞膜中的不饱和脂防酸的减少,可能是降低膜脂流动性的原因之一。 相似文献
72.
大斑啄木鸟取食行为的研究 总被引:4,自引:0,他引:4
大斑啄木鸟(Dendrocopos major)是左家地区的常见鸟类,对它的研究,国内有过一些报道。1990年4—5月,笔者对它的取食行为做了较为系统的观察,现整理报道如下。 相似文献
73.
74.
从浙江产蝮蛇毒中分离出一种凝血酶样酶,该酶能明显地延长全血凝固时间,白陶土部分凝血活酶时间(KPTT),并降低了血浆中的纤维蛋白原水平,同时全血的比粘度和血浆的比粘度及血清中的胆固醇和β脂蛋白均有所下降.该酶不激活凝血因子ⅩⅢ. 相似文献
75.
76.
Cloning and structural analysis of cDNA and the gene for mouse transcription factor UBF 总被引:21,自引:7,他引:14 下载免费PDF全文
K Hisatake T Nishimura Y Maeda K Hanada C Z Song M Muramatsu 《Nucleic acids research》1991,19(17):4631-4637
77.
1. 1.|When Chinese hamster ovary cells are treated with cycloheximide (10 μg/ml) or puromycin (100 μg/ml) for 2 h before and during heating at 43°C for 3 h, there is protection from hyperthermic killing; i.e. the plating efficiency increases 2000-fold from 3.7 × 10−5 to (6–9) × 10−2.
2. 2.|The total intracellular levels of spermidine and spermine are not altered by the hyperthermic or drug treatments.
3. 3.|The small 30% decrease in intracellular putrescine observed after heating is not altered by drug treatment.
4. 4.|Heat protection by treatment with cycloheximide or puromycin cannot be attributed to changes in levels of total intracellular polyamines.
78.
The effect of fluorosis on lactation, lactotroph function and ultrastructure were studied in lactating rats. The results were as follows: 1) Inhibition of lactation in lactating rats with chronic fluorosis was assessed by stunting growth of pups and decrease in the amount of milk suckled by pups in 30 min. Metoclopramide, a blocker of dopamine receptor, could improve lactation in these rats. 2) During chronic fluorosis serum PRL level was decreased, however, PRL content in pituitary was increased. Electronmicroscopic examination showed accumulation of large mature secretory granules and appearance of extremely large abnormal secretory granules in lactotroph cytoplasma. These findings indicate that hormone release of pituitary lactotrophs is obstructed in lactating rats with fluorosis, and the toxic effect of fluoride is mediated by an enhanced function of dopaminergic system in hypothalamus. 相似文献
79.
F Ikemoto G Song M Tominaga K Yamamoto 《Biochemical and biophysical research communications》1988,153(3):1032-1037
The activity of angiotensin converting enzyme(ACE) in crude extracts of the rat renal cortex was increased when the oxidizing agent diamide was added to the extract. The maximal activity was obtained at concentrations over 1 mM, and the value was twice or more the activity in the absence of the pretreatment. The activity of ACE was also increased by the diamide-pretreatment of the isolated membrane fraction of the renal cortex, thereby indicating that the increase in activity was not due to oxidation of endogenous glutathione (GSH) that may lower the ACE activity, but rather that ACE itself was oxidized. When O2 was included in the extract for 2 h, the ACE activity also increased to about twice the original activity. Lineweaver-Burk plots analysis demonstrated that, after oxidation with diamide and O2, the Vmax was increased but the Km remained unchanged. We conclude that the action of ACE in the kidney functions may differ in relation to oxidation of the tissue. 相似文献
80.
Tryptophan (Trp) fluorescence quenching of phytochrome has been studied using anionic, cationic and neutral quenchers, I-, Cs+ and acrylamide, respectively, in an effort to understand the molecular differences between the Pr and Pfr forms. The data have been analyzed using both Stern-Volmer and modified Stern-Volmer kinetic treatments. The anionic quencher, I-, was proven to be an ineffective quencher with Stern-Volmer constants, Ksv, of 0.60 and 0.63 M-1, respectively, for the Pr and Pfr forms of phytochrome. The cationic quencher, Cs+, showed about a 2-fold difference in the Ksv of Pr and Pfr, indicating a significant change in the fluorescent Trp environments during the Pr to Pfr phototransformation. However, only 25-37% of the fluorescent Trp residues were accessible to the cationic quencher. Most of the fluorescent Trp residues were accessible to acrylamide, but the quenching by acrylamide was indistinguishable for the Pr and Pfr forms. An additional quenching by acrylamide after a saturated quenching with Cs+ showed more than 40% increase in the Ksv of Pfr over Pr. These observations, along with the finding of two distinct components in the Trp fluorescence lifetime, indicate the existence of Trp residues in at least two different sets of environments in the phytochrome protein. The two components of the fluorescence had lifetimes of 1.1 ns (major) and 4.7 ns (minor) for Pr and 0.9 ns (major) and 4.6 ns (minor) for Pfr. Fluorescence quenching was found to be both static and dynamic as the Stern-Volmer constants for the steady-state fluorescence quenching were higher than for the dynamic fluorescence quenching. Based on the quenching results, in combination with the location of Trp residues in the primary structure, we conclude that the Pr to Pfr phototransformation involves a significant conformation change in the phytochrome molecule, preferentially in the 74 kDa chromophore-bearing domain. 相似文献