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991.
992.
Our previous studies have shown that heat shock and nutritional stress produce an increase in UV resistance and a decrease in UV-induced mutation frequency in DNA repairproficient strains ofEscherichia coli K12. The effect depends on nucleotide excision repair and requires protein synthesis. We now show that comparable changes occur after oxidation stress, exposure to ethanol, or osmotic shock, all in conditions that do not affect the natural mutation frequency. The results support the hypothesis that many unrelated, nonmutagenic treatments elicit a common protective response in these cells that involves induction of an error-free DNA excision repair system. 相似文献
993.
Chemoreceptor synapses in the carotid body 总被引:2,自引:0,他引:2
994.
N Takahashi H Kakinuma K Hamada K Shimazaki K Takahashi S Niihata Y Aoki H Matsushita Y Nishi 《European journal of biochemistry》1999,261(1):108-114
One of the major obstacles to acquiring catalytic antibodies is that it requires labor-intensive procedures to select catalytic antibodies from huge repertories of antibodies. Here, we selected potential catalytic Abs by utilizing their affinity towards a short transition-state analog which contained only the transition-state structural element, and evaluated in detail its efficiency to enrich catalytic Abs. Hybridoma supernatants elicited against a phosphonate derivative, the TSA1, were screened by a three-step screening process: step 1, ELISA for TSA1-BSA; step 2, ELISA for the short TSA4; and step 3, competitive-inhibition by the short TSA2. Only 22. 8% of positive mAbs from step 1 were found to be catalytic. The rate of catalytic Abs increased to 45.7% using screening steps 1 plus 2, and reached 83.3% using all three screening steps. This clearly suggests that our screening protocol is an efficient method to select potential catalytic Abs. Furthermore, we characterized the properties of both the catalytic Abs and the noncatalytic Abs in detail. The catalytic Abs tended to have lower Kd for TSA1 and the short TSA2 than noncatalytic Abs. It was also observed that catalytic Abs showed clear enantiospecificity toward substrate 6 containing d-phenylalanine while noncatalytic Abs did not. The detailed analysis of kinetic and binding parameters for these antibodies gives us further insight into catalytic antibodies. 相似文献
995.
996.
Steroid hormones and their receptors in the brain 总被引:2,自引:0,他引:2
Mitsuhiro Kawata Kazunari Yuri Hitoshi Ozawa Mayumi Nishi Takao Ito Zhongting Hu Haiping Lu Maki Yoshida 《The Journal of steroid biochemistry and molecular biology》1998,65(1-6):273-280
Steroid hormones regulate several important functions of the brain by altering the expression of particular genes through their receptors. First in this paper the localization of glucocorticoid receptor immunoreactivity and mRNA in the brain was examined. Second biphasic effects of glucocorticoid on the hippocampus was described and particular emphasis was given on the apoptosis. Third the significance of estrogen receptor in the sexually dimorphic areas was discussed. These results suggest that steroids modulate the gene expression along with the alteration of cell structures in a different manner in a tissue-specific pattern. 相似文献
997.
Rabbit small-intestinal microvilli isolated by a Ca2+ precipitation method contain a 33 kD protein, which has not been observed in microvilli isolated in the presence of Ca2+-chelators. The intracellular localization of this protein in rabbit intestinal epithelial cells was studied by immunofluorescence and immunoperoxidase microscopy, and was compared with that of aminopeptidase M, a well-known microvillus membrane-bound enzyme. The results obtained show that the 33 kD protein is located in the inside of the microvillus, but not in the terminal web of the epithelial cell. The protein may also be located on the basolateral surface of the cell. 相似文献
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