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51.
Keith G. Danielson Janice E. Knepper Frances S. Kittrell Janet S. Butel Daniel Medina Elisa M. Durban 《In vitro cellular & developmental biology. Plant》1989,25(6):535-543
Summary Clonal populations were isolated from the mouse mammary cell line, COMMA-D, by transfection with a dominant-selectable gene,
pSV2Neo, which confers resistance to the antibiotic, G418. Seven of twenty-four clones isolated retained the ability of the
parental line to repopulate cleared mammary fat pads in vivo as ductal-alveolar hyperplasias. Two sublines designated CDNR2
and CDNR4 retained hyperplastic growth potential after multiple passages in vitro with low incidence of tumor formation. A
third subpopulation, CDNR1, contained a single integration site for the pSV2Neo plasmid indicating a bonafide clonal origin
for this subline. CDNR1 cells displayed heterogeneous growth phenotypes in vivo including hyperplasia, adenocarcinoma, and
bone formation. Functional differentiation of CDNR1 cells organized as alveolarlike structures in vivo or on floating collagen
gels in vitro was observed as determined by immunoperoxidase staining for the milk-specific protein, casein. Overall, the
results indicate that a subset of cells from the COMMA-D cell line may be functionally analogous to stem cells existing in
the mammary gland.
Supported by NCI research grants CA-38650, CA-33369, CA-39017, and CA-25215. 相似文献
52.
A method for the detection of the specific binding of 3-methylcholanthrene to rat liver cytosolic proteins is described. The separation of the protein-bound 3-methylcholanthrene from the free 3-methylcholanthrene was achieved using a batch DEAE-cellulose technique. Extraction of the DEAE-cellulose with 0.3 M KCl allowed the selective release and measurement of the amount of protein-bound 3-methylcholanthrene. The assay was optimized for the following parameters: time of incubation with DEAE-cellulose, time required for salt extraction, protein concentration, the concentration of KCl required to elute the specific binding proteins, the amount of DEAE-cellulose required to bind the specific binding proteins, and ligand specificity. The sedimentation properties of those 3-methylcholanthrene-binding proteins which were extracted with salt from DEAE-cellulose were examined on 5 to 20% sucrose gradients; the major binding species sedimented as a broad peak at 4.5 S. 相似文献
53.
Differential regulation of basic protein phosphorylation by calcium phospholipid and cyclic-AMP-dependent protein kinases 总被引:2,自引:0,他引:2
Myelin basic protein, an 80-kilodalton (kDa) protein in rat oligodendrocytes, and an 80-kDa basic protein in neuroblastoma x neonatal Chinese hamster brain explant hybrids were phosphorylated extensively when the cells were treated with either phorbol esters (TPA) or diacylglycerols (e.g., oleyoyl-acetylglycerol). TPA-stimulated phosphorylation was inhibited by pre-incubation with 50 microM psychosine (galactosyl-sphingosine), confirming that it is mediated through the phospholipid-dependent protein kinase C (PK-C). Surprisingly, phosphorylation of these proteins was inhibited by incubation of cells with agents which result in activation of cyclic-AMP-dependent protein kinase (dibutyryl cyclic AMP or forskolin). In contrast, phosphorylation of other nonbasic proteins, for example, the oligodendrocyte-specific 2',3'-cyclic nucleotide phosphohydrolase, was stimulated under these conditions (Vartanian et al.: Proceedings of the National Academy of Sciences of the United States of America 85:939, 1988). The possible role of cyclic AMP in activating specific phosphatases or restricting the availability of diacylglycerol for PK-C activation is discussed. 相似文献
54.
Ranganathan Santhanam 《Inorganica chimica acta》2008,361(2):473-478
A novel method of preparation of hexahydroaluminate complexes M3AlH6 (M = Li, Na or K) from the corresponding alkali metal hydride and tetrahydroaluminate has been explored, using dimethyl ether (Me2O) as a solvent at near-ambient temperatures. The results are compared with those obtained using a recently established mechanochemical approach. Characterization of the products by powder X-ray diffraction revealed M3AlH6 to be formed in high yield for M = Li and Na, but not for M = K. The attempted preparation of Li2NaAlH6 and Li2KAlH6 was unsuccessful. 相似文献
55.
Abstract: The enzymatic hydrolysis of UDP-galactose in rat and calf brain was studied. The hydrolysis occurs in two steps: The first is the conversion of UDP-galactose to galactose-1-phosphate catalyzed by nucleotide pyrophosphatase (EC 3.6.1.9), and the second is the conversion of the latter to free galactose by alkaline phosphatase (EC 3.1.3.1). The overall conversion has a pH optimum of 9.0, but there is considerable activity at pH 7.4, which is the optimum for UDP-galactose:ceramide galactosyltransferase in the synthesis of cerebrosides. Preparations from cytosol from calf brain cerebellum or stem that were enriched in UDP-galactose hydrolytic activity inhibit cerebroside synthesis under conditions optimal for the synthesis. Microsome-rich and nuclear debris fractions contain the highest apparent specific activity among the subcellular fractions studied. Hydrolysis of UDP-galactose occurs in all areas of brain, brainstem having the highest activity. The apparent specific activity in jimpy mouse brain homogenate is nearly twice as high as in the control brain homogenate. 相似文献
56.
57.
Ian R. Brown 《Journal of neurochemistry》1983,40(5):1490-1493
Abstract: Analysis of the cell-free translation products of polysomes isolated from fetal brain and other organs indicates that elevation of maternal body temperature induces the synthesis of a heat shock protein of molecular weight 74,000 (74K). The newborn mammal is particularly sensitive to induction of the 74K protein. As early postnatal development proceeds, higher body temperatures are required to induce synthesis of the 74K heat shock protein. 相似文献
58.
Summary Lysine-rich proteinoids in aqueous solution catalyze the formation of peptides from free amino acids and ATP. This catalytic activity is not found in acidic proteinoids, even though the latter contain some basic amino acid. The pH optimum for the synthesis is about 11, but is appreciable below 8 and above 13. Temperature data indicate an optimum at 20°C or above, with little increase in rate to 60°C. Pyrophosphate can be used instead of ATP, with lesser yields resulting. The ATP-aided syntheses of peptides in aqueous solution occur with several types of proteinous amino acid.Proofs should be sent to S.W. Fox, Institute for Molecular and Cellular Evolution, University of Miami, 521 Anastasia Avenue, Coral Gables, FL 33134 相似文献
59.
VESICULAR-ARBUSCULAR MYCORRHIZAS OF GINKGO BILOBA L. IN NATURAL AND CONTROLLED CONDITIONS 总被引:1,自引:1,他引:0
ANNA FONTANA 《The New phytologist》1985,99(3):441-447
60.