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991.
A new experimental model of glucocorticoid-induced tubular cyst formation has been developed in metanephric organ culture. The addition of cortisol (1.4 X 10(-5) M) to chemically defined serum-free culture medium produces cystic changes during in vitro nephrogenesis . The model isolates the role of glucocorticoids in experimental cyst formation. 相似文献
992.
Kato Y. Fusetani N. Matsunaga S. Hashimoto K. 《Cellular and molecular life sciences : CMLS》1986,42(11-12):1299-1300
Cellular and Molecular Life Sciences - Two novel furanosesterterpenes, okinonellins A (1) and B (2), have been isolated from the spongeSpongionella sp. Both compounds inhibit cell division of... 相似文献
993.
994.
Cellular and Molecular Life Sciences - 相似文献
995.
Identification of the V factor needed for synthesis of the iron-molybdenum cofactor of nitrogenase as homocitrate 总被引:5,自引:0,他引:5
T R Hoover A D Robertson R L Cerny R N Hayes J Imperial V K Shah P W Ludden 《Nature》1987,329(6142):855-857
Nitrogenase catalyses the ATP-dependent reduction of N2 to NH3, and is composed of two proteins, dinitrogenase (MoFe protein or component I) and dinitrogenase reductase (Fe protein or component II). Dinitrogenase contains a unique prosthetic group (iron-molybdenum cofactor, FeMoco) comprised of Fe, Mo and S, which has been proposed as the site of N2 reduction. Biochemical and genetic studies of Nif- (nitrogen fixation) mutants of Klebsiella pneumoniae which are defective in nitrogen fixation, have shown that the nifB, nifQ, nifN, nifE and nifV genes are required for the biosynthesis of FeMo-co. Recently, a system for in vitro synthesis of FeMoco was described. The assay requires at least the nifB, nifN and nifE gene products, and a low-molecular-weight factor (V factor) produced in the presence of the nifV gene product. We have used this system to study FeMoco biosynthesis. We report here the isolation of V factor and identify it as homocitric acid ([R]2-hydroxy-1,2,4-butanetricarboxylic acid). 相似文献
996.
Cholera toxin genes: nucleotide sequence, deletion analysis and vaccine development 总被引:25,自引:0,他引:25
Nucleotide sequence and deletion analysis have been used to identify the regulatory and coding sequences comprising the cholera toxin operon (ctx). Incorporation of defined in vitro-generated ctx deletion mutations into Vibrio cholerae by in vivo genetic recombination produced strains which have practical value in cholera vaccine development. 相似文献
997.
998.
N. Tran 《Cellular and molecular life sciences : CMLS》1972,28(9):1021-1022
Sommaire Les résultats obtenus démontrent une inhibition de l'activité de la DOPA decarboxylase par de haute concentration de PLP ou de faible concentration del-DOPA plus PLP. Ceci pourrait expliquer les observations cliniques et expérimentales précédentes démontrant que la pyridoxine antagonise l'effet del-DOPA utilisé dans le traitement de la maladie de Parkinson. 相似文献
999.
Before their recognition by T lymphocytes, protein antigens generally require processing by antigen-presenting cells. In a poorly understood series of events, the protein antigen is internalized, transformed and re-expressed on the surface of the antigen-presenting cell in association with gene products of the major histocompatibility complex (MHC). Small peptides derived from the native protein can be recognized in the absence of antigen processing, suggesting that processing involves proteolytic degradation. These peptides are thought to mimic the naturally produced peptide fragment. We describe here a synthetic peptide antigen of this type which does not require processing but which is nevertheless further processed by splenic antigen-presenting cells. Interestingly, this processing event specifically alters the interaction of the peptide with the class II MHC (Ia) molecule, markedly affecting both its potency as an antigen in vitro and its immunogenicity in vivo (IR gene control). 相似文献
1000.