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Summary A selection method has been developed for the isolation of recombinant strains of Trichoderma reesei QM 9414. The method is based on somatic hybridization via anastomosis or protoplast fusion, and on the difference in growth rate of the resulting heterokaryons and synkaryons. The more intensive growth of the synkaryons as due to allelic complementation of adenine-requiring auxotrophic strains mutated in the adenylosuccinate synthetase gene. The synkaryons appeared is energetically growing spots in the heterokaryotic background. Stable diploids could not be isolated, which points to the transient nature of the diploid state in this species. 相似文献
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Polyethylenimine selectivity precipitates a large fraction of the proteins present in a crude Drosophila embryonic extract. While the free catalytic subunit of the cAMP dependent protein kinase is quantitatively retained in the soluble fraction after polyethylenimine precipitation, the rest of the abundant and highly active protein kinases present in the embryo are quantitatively precipitated. The catalytic subunit of the cAMP dependent protein kinase was purified until apparent homogeneity from the soluble protein fraction after polyethylenimine precipitation. The pH optimum of the purified enzyme is 6.3. While magnesium is the preferred divalent cation for all the cAMP dependent protein kinases described previously, the Drosophila enzyme is three times more active if manganese is present as divalent cation compared with magnesium. The enzyme is tost active between 50–100 mM monovalent ion concentration. Heparin can selectively modulate the phosphorylation of different substrate proteins. 相似文献
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Bradykinin (BK) is a peptide hormone with sequence Arg1-Pro2-Pro3-Gly4-Phe5-Ser6-Pro7-Phe8-Arg9 and has been implicated in a multitude of pathophysiological processes such as the ability to lower systemic blood pressure and stimulate pain. BK analogues having bulky, β-branched D -aliphatic residues at position 7 combined with bulky L -aliphatic residues at position 8 have now been observed to be strong antagonists. Conformational studies based on two-dimensional nmr experiments in methanol/water (80/20 v/v) were carried out on several such active antagonists in a polar solvent. Included in this study were the very active antagonists, [D -Arg0, Hyp3, Thi5, D -Cpg7, Cpg8]-BK [Cpg: α-cyclo-pentyl-glycine; Hyp: trans-4-hydroxy-L -proline; Thi: β-(2-thienyl)-L -alanine] ( I ), [D -Arg0, Hyp3, D -Cpg7, Cpg8] -BK ( II ), as well as its variant with D -Cpg7 replaced by Cpg7, namely [D -Arg0, Hyp3, Cpg7, Cpg8]-BK ( III ). A turn-like structure, which coexists with the extended conformation, was observed between residues 2 and 5 for the most active antagonists I and II , in direct correlation with the peptide activities. No turn-like structure was found for residues 6–9. In peptide III , a turn-like structure was not identified. The existence of a turn at the C-terminal end of bradykinin and its analogues has been predicted by empirical calculations and supported by nmr measurements. But the present nmr study on the most active antagonists ( I , II ) does not support this hypothesis. Instead, the data suggest that a turn-like structure between residues 2 and 5 could be important for antagonist activity. Finally, one weak inhibitor [D -Cpg7]-BK ( IV ) showed no defined secondary structure. © 1993 John Wiley & Sons, Inc. 相似文献
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Eszter Gács-Baitz Lajos Radics G.B. Oganessian Vilen A. Mnatsakanian 《Phytochemistry》1978,17(11):1967-1973
The structure and stereochemistry of teucrins H1, H2, H3 and H4, four novel diterpenes from Teucrium hyrcanicum have been established by detailed studies of the PMR and 13C NMR spectra, CD results and chemical transformations. Teucrin H4, a minor constituent is shown to possess a unique stereochemistry hitherto not reported for related diterpenoids. 相似文献
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Mária Sasvári-Székely Gábor Szabó Mária Staub Tatjana Spasokukotskaja Ferenc Antoni 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1983,762(3):452-457
The DNA synthesis system of freshly isolated tonsillar lymphocytes and those stimulated by phytohaemagglutinin were compared by different methods. Both cell populations had high DNA polymerase α and thymidine kinase activities, as well as a high rate of incorporation of [3H]thymidine into DNA. However, the two cell populations differed when their DNA distributions were compared by flow cytometry. Freshly isolated cells contained many less (6%) cells in S phase than were found in phytohaemagglutinin-stimulated lymphocytes (18%) as detected by flow cytometry. The labelling of different subpopulations of lymphocytes was studied by sorting them electrically with a fluorescence-activated cell sorter. Analysis of the radioactivity of [3H]thymidine pulse-labelled cells, sorted according to their DNA content, showed that cells in the G1 peak of DNA distribution had a significant amount of incorporated [3H]thymidine. Sorting of cells according to their size (i.e., by light scattering) revealed that only large cells were labelled with [3H]thymidine. 相似文献
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Based on 388 parallel data of phytoplankton biomass and chlorophyll-a of two shallow lakes and two ponds, the following results were obtained:
- Relative chlorophyll-a content of phytoplankton biomass varied between 0.08–1.88%; chlorophyll-a concentration showed great differences among lakes.
- Significant correlations (r = 0.68–0.92) were established between phytoplankton biomass and chlorophyll-a concentration. The regression in the artificial ponds was non-linear.
- In parallel with the increase of average cell volume, a decrease in relative chlorophyll-a content was observed. A significant correlation (r = + 0.83) between the two variables was found. Relative chlorophyll-a content of phytoplankton is a log-function of average cell volume.
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Intravenous administration of 10 to 40 U/g b.w. glucose oxidase produced hypoglycaemia in a dose-dependent manner. The enzyme-induced drop of the blood sugar level was associated with significant rise in serum potassium and the concentration of free fatty acids. Intracerebral application of glucose oxidase through chronically implanted cannula into the ventromedial, lateral hypothalamus, preoptic region and amygdaloid complex of nuclei failed to change the blood sugar level, although a moderate increase of the free fatty acids and corticosterone concentrations occurred. The local application of enzyme in the locus coeruleus region led to a significant rise of the blood sugar concentration. The observations suggest the sensitivity of brainstem catecholaminergic neuronal system to hypoglycaemia. 相似文献
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