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1.
Effects of viral transformation on synthesis and secretion of collagen and fibronectin-like molecules by embryonic chick chondrocytes in culture 总被引:4,自引:0,他引:4
Monolayer cultures of chondrocytes isolated from 11-day-old chick embryo vertebral cartilage were transformed by Rous sarcoma virus, and the effects of transformation on synthesis and secretion of extracellular proteins by these cells were studied. Transformation resulted in decreased synthesis of type II collagen which did not appear to be due to underhydroxylation of collagenous protein but to a decrease in the total amount synthesized. Carboxymethyl-cellulose chromatography and polyacrylamide disc gel electrophoresis failed to demonstrate any alpha 2 chains as a result of the transformation, suggesting that conversion of type II to type I collagen did not occur. In contrast to the decrease in collagen synthesis, synthesis of a molecule with biochemical characteristics similar to fibronectin increased markedly in virally transformed cultures. Although there were no significant differences in the amount of fibronectin-like molecules in the cell layers of normal and transformed chondrocytes, a marked increase of these molecules in the culture media of the transformed cells was demonstrated. These findings were confirmed by experiments with temperature-sensitive mutants of the virus. 相似文献
2.
J G Fukushima O Cascone J A Santomé M J Biscoglio de Jimenez Bonino 《International journal of peptide and protein research》1987,30(3):365-370
Reactivity of histidine residues in equine growth hormone to ethoxyformic anhydride was studied. The existence of two kinetically different sets was demonstrated: one of them including only the slow reacting histidine 169 (k = 0.164 min-1) and the other containing fast reacting histidines 19 and 21 (k = 0.892 min-1). A correlation between the decrease in the capacity to compete with 125I-labeled hormone for rat liver binding sites and the degree of ethoxyformylation of the fast group was found. Circular dichroism studies indicated no significant conformational changes in the protein with all three residues modified. These results fully agree with those obtained for bovine growth hormone which is further evidence supporting the vinculation of histidines 19 and/or 21 with the binding site of these hormones to their specific receptors. 相似文献
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Biochemical characteristics and fatty acid compositions of some armadillo-derived mycobacteria and their relation to Mycobacterium gordonae 总被引:1,自引:0,他引:1
The long-chain components of 75 strains of mycobacteria, cultivated from Mycobacterium leprae-infected or non-infected armadillos, and of eight clinical and 15 environmental isolates of M. gordonae, were compared. Four major groups could be distinguished based on the presence of 10-methyloctadecanoic (tuberculostearic) and 2-methyl 3-hydroxyeicosanoic acids and secondary alcohols (2-octadecanol and 2-eicosanol). Some heterogeneity was found in strains assigned to M. gordonae: the characteristic absence of tuberculostearic acid and secondary alcohols and the presence of the branched C14 and the hydroxylated C20 acids were seen in only 34 of the 49 strains studied. Three strains were identified as M. malmoense, one as M. kansasii, ten as belonging to the M. avium-M. intracellulare-M. scrofulaceum complex and eight as belonging to new groups of armadillo-derived mycobacteria (ADM 1, ADM 2 and ADM 3) by conventional bacteriological tests and fatty acid compositions, though M. malmoense was heterogeneous in its fatty acids composition. Four strains, identified as M. avium by conventional tests, differed from this species by their fatty acid compositions. Thirteen strains showed some similarity to M. simiae and ten strains differed from all other known mycobacteria. 相似文献
6.
A new method for demonstrating argyrophil cells of the pancreas and intestinal tract using a combined silver and reducing solution in sections of formaldehyde fixed tissue is described. Impregnating sections in a 60 C water bath, the procedure takes about 25 min. A microwave version that takes about 5 min is also given. Results are similar to those obtained with the Grimelius method for argyrophil cells. 相似文献
7.
Structure of cDNA clones coding for human type II procollagen. The alpha 1(II) chain is more similar to the alpha 1(I) chain than two other alpha chains of fibrillar collagens. 总被引:8,自引:0,他引:8
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C T Baldwin A M Reginato C Smith S A Jimenez D J Prockop 《The Biochemical journal》1989,262(2):521-528
Overlapping cDNA clones were isolated for human type II procollagen. Nucleotide sequencing of the clones provided over 2.5 kb of new coding sequences for the human pro alpha 1(II) gene and the first complete amino acid sequence of type II procollagen from any species. Comparison with published data for cDNA clones covering the entire lengths of the human type I and type III procollagens made it possible to compare in detail the coding sequences and primary structures of the three most abundant human fibrillar collagens. The results indicated that the marked preference in the third base codons for glycine, proline and alanine previously seen in other fibrillar collagens was maintained in type II procollagen. The domains of the pro alpha 1(II) chain are about the same size as the same domains of the pro alpha chains of type I and type III procollagens. However, the major triple-helical domain is 15 amino acid residues less than the triple-helical domain of type III procollagen. Comparison of hydropathy profiles indicated that the alpha chain domain of type II procollagen is more similar to the alpha chain domain of the pro alpha 1(I) chain than to the pro alpha 2(I) chain or the pro alpha 1(III) chain. The results therefore suggest that selective pressure in the evolution of the pro alpha 1(II) and pro alpha 1(I) genes is more similar than the selective pressure in the evolution of the pro alpha 2(I) and pro alpha 1(III) genes. 相似文献
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In the present study we attempt to determine the principal factors which influence the contamination by Penicillium of 116 samples of pre-harvest corn from five crop areas in Valencia (Spain).In the corn tested, Penicillium is the most abundant genus after Fusarium, with an incidence of 71.5% in infected samples, counts of about 642 cfu/g and kernel infection of 8.7%. The most frequently isolated species are Penicillium chrysogenum, P. steckii and P. purpurogenum.There is a high correlation between the contamination from this genus and the amout of kernels broken and infested by insects, as well as a correlation with crop areas.We have found no difference in the contamination of the two varieties of corn investigated. 相似文献
10.
Bovine t hymic peptide extract (1–100 g/ml) is shown to completely inhibit the binding of [125I]VIP to rat blood mononuclear cells, lymphoid cells of spleen, and liver plasma membranes. In the three models, the bovine thymic peptide extract inhibits [125I]VIP binding with a potency that is 4000–7000 times lower than that of the native VIP, on a weight basis. In rat liver plasma membranes, the bovine thymic peptide extract stimulates adenylate cyclase with a maximal efficiency that is similar to that of VIP. At maximal doses, VIP and thymic peptide extract do not exert an additive effect on adenylate cyclase, suggesting that the activation of the enzyme by the bovine thymic peptide extract occurs through VIP receptors. Finally, no VIP-like immunoreactivity was detected in the thymic peptide extract using an antiserum raised against mammalian VIP. All these data suggest the presence in the bovine thymic peptide extract of a new substance which behaves as a VIP agonist in rat. 相似文献