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191.
192.
Linda E. Malick Anna Tompa Charles Kuszynski Parviz Pour Robert Langenbach 《In vitro cellular & developmental biology. Plant》1981,17(11):947-955
Summary The maintenance of primary cultures of adult hamster pancreatic cells on layers of irradiated C3H/10T1/2 cells was studied.
Various types of pancreatic cells, acinar, islet and ductular cells could be identified in the cultures by light and electron
microscopy. Morphologically the various pancreatic cells retained many differentiated characteristics of their respective
in vivo cell types. Insulin production was maintained at near Day 1 levels for the 16 d in culture for which it was measured.
Colonies of epithelial cells continued to grow during a 20 d culture period. It is believed that this procedure for maintaining
functional and growing pancreas cells in culture may be a useful in vitro model for studying the initiation of pancreatic
carcinogenesis.
Supported by Grant R01 CA 20022 and Contract N01 CP33278 from the National Cancer Institute, National Institutes of Health,
Bethesda, Maryland. 相似文献
193.
Anna Fietta Guido Grandi Massimo Malcovati Gianna Valentini Vittorio Sgaramella Antonio G. Siccardi 《Plasmid》1981,6(1):78-85
Plasmids S-a and Rts1 suppress the galactose-sensitive phenotype of galE mutants of Escherichia coli K-12, giving rise to both galactose-fermenting and nonfermenting strains. Fermenting strains produce normal inducible UDP-galactose epimerase. Plasmids extracted from either a fermenting or a nonfermenting strain are indistinguishable when examined by either measurements of length of relaxed circular molecules by electron microscopy or electrophoretic pattern of restriction endonuclease digestion products. The phenomenon could be explained by reversible recombination between a plasmid-borne epimerase gene and homologous chromosomal sequences. 相似文献
194.
Pasquale Petrilli Pietro Pucci Anna Maria Garzillo Giovanni Sannia Dr. Gennaro Marino 《Molecular and cellular biochemistry》1981,35(2):121-128
Summary Reactivity of sulphydryl groups of cytosolic and mitochondrial aspartate aminotransferases from ox heart has been studied.
A total of 5 and 7 cysteine residues per monomer are present in cAATo and mAATo, respectively. In native conditions only a
single sulphydryl group can be titrated by Nbs2 while the catalytic activity remains unchanged, however in the mitochondrial isozyme the reactivity depends on the functional
state of the enzyme. Reactivity toward NEM reveals the existence of a syncatalytic sulphydryl group in the cytosolic isozyme.
Titration of cAATo with pMB at pH 8 and pH 5 confirms the existence of two exposed sulphydryl groups with a different reactivity.
The results compared with those reported on the corresponding isozymes from pig and chicken heart show that syncatalytic sulphydryl
groups are of general occurrence in these enzymes. 相似文献
195.
196.
197.
Ryszard Farbiszewski Anna Wincewicz Wiktor Rzeczycki 《Molecular and cellular biochemistry》1977,17(1):3-6
Summary Arginine-rich basic protein from cytoplasma of Guerin epitheliomas has been isolated and characterized. It contains five amino acids: arginine, lysine, glycine, alanine and glutamic acid which make together 74 per cent of all amino acid residues. The protein has a cationic character with an isoelectric point of 8.2. No carbohydrate component was found in this protein. The significance of arginine-rich basic protein in the cytoplasma of Guerin epithelioma is discussed briefly. 相似文献
198.
Summary Albino mice were injected intraperitoneally with tritiated thymidine and killed 1/2 and 30 h later. Pieces of ileum were excised and fixed. Tissue sections were hydrolyzed with 5 N HCl at 21° C for 1/2, 1, 2, 3, 4 and 6 h, some sections remained unhydrolyzed. Both the hydrolyzed and nonhydrolyzed sections were autoradiographed. Grain counts per labelled nucleus of either cryptal (DNA-synthesizing) or villous (DNA-nonsynthesizing) cells nonhydrolyzed and hydrolyzed for various time intervals were recorded.The results indicate, that the grain count of nonhydrolyzed, labelled nuclei from cryptal cells was by 1.49 higher than that of villous cells demonstrating the rate of grain counts diminution caused by cell divisions.Hydrolysis caused a diminution of grain count of cryptal cells by approximately 15% higher than that of the grain count of villous cells.Financial support was partially obtained from grant MR II.1.We wish to thank Dr. W. Sawicki for his supervision, advice and encouragement throughout this work 相似文献
199.
200.
Multiple components in two antigenic variants of staphylococcal exfoliative toxin were demonstrated by isoelectric focusing in polyacrylamide gel. The main components had an isoionic point of pH=7.0 while other components ranged from pI=4.5 to pI=8.5. Each individual component was shown to possess full biologic and serologic activity after focusing. Isoelectric focusing in the presence of 8 M urea also showed microheterogeneity in exfoliative toxin preparations. The various components appear to be reversible conformers, possibly raised by exposure to the ph gradient of the ampholines. 相似文献