45 research outputs found

    Survey on Dropouts from Graduate Schools of Social Work, 1970-1972

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    This research project has been designed as an initial exploratory survey of dropouts from graduate schools of social work. The target population was those students who had dropped from graduate schools of social work accredited by the Council on Social Work Education. The time frame covered a three year period from 1970 to 1972. The data was gathered through the development and administration of a survey instrument in questionnaire form

    A specific role for the phosphorylation of mammalian acidic ribosomal protein P2.

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    International audienceThe acidic ribosomal proteins P1-P2 from rat liver were overproduced for the first time by expression of their cDNA in Escherichia coli. They were tested for their ability to reactivate inactive P1-P2-deficient core particles derived from 60 S ribosomal subunits treated with dimethylmaleic anhydride, in poly(U)-directed poly(Phe) synthesis. The recombinant P1-P2 were unable to reactivate these core particles although they could bind to them. When recombinant P1-P2 had been phosphorylated first with casein kinase II, they were as efficient in the reactivation process as P1-P2 extracted with ethanol/KCl from the 60 S subunits. Reconstitution experiments were carried out using all possible combinations of the two recombinant proteins phosphorylated or not. Reactivation of the core particles required the presence of both P1 and P2 with the latter in its phosphorylated form. These experiments reveal a distinct role for P1 and P2 in protein synthesis. Phosphorylated P2 produced a partial quenching of the intrinsic fluorescence of eukaryotic elongation factor 2, which was not observed with the unphosphorylated protein. This result demonstrates the existence of an interaction between phosphorylated P2 and eukaryotic elongation factor 2. P2 also quenched part of the intrinsic fluorescence of P1, due to the interaction between the two proteins.The acidic ribosomal proteins P1-P2 from rat liver were overproduced for the first time by expression of their cDNA in Escherichia coli. They were tested for their ability to reactivate inactive P1-P2-deficient core particles derived from 60 S ribosomal subunits treated with dimethylmaleic anhydride, in poly(U)-directed poly(Phe) synthesis. The recombinant P1-P2 were unable to reactivate these core particles although they could bind to them. When recombinant P1-P2 had been phosphorylated first with casein kinase II, they were as efficient in the reactivation process as P1-P2 extracted with ethanol/KCl from the 60 S subunits. Reconstitution experiments were carried out using all possible combinations of the two recombinant proteins phosphorylated or not. Reactivation of the core particles required the presence of both P1 and P2 with the latter in its phosphorylated form. These experiments reveal a distinct role for P1 and P2 in protein synthesis. Phosphorylated P2 produced a partial quenching of the intrinsic fluorescence of eukaryotic elongation factor 2, which was not observed with the unphosphorylated protein. This result demonstrates the existence of an interaction between phosphorylated P2 and eukaryotic elongation factor 2. P2 also quenched part of the intrinsic fluorescence of P1, due to the interaction between the two proteins

    Interaction of elongation factor eEF-2 with ribosomal P proteins.

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    International audienceThe eukaryotic P1 and P2 ribosomal proteins which constitute, with P0, a pentamer forming the lateral stalk of the 60 S ribosomal subunit, exhibit several differences from their prokaryotic equivalents L7 and L12; in particular, P1 does not have the same primary structure as P2 and both of them are phosphorylated, the significance of the latter remaining unclear. Rat liver P1 and P2 were overproduced in Escherichia coli cells and their interaction with elongation factor eEF-2 was studied. Both recombinant proteins were found to be required for the ribosome-dependent GTPase activity of eEF-2, with P2 in the phosphorylated form. The surface plasmon resonance technique revealed that, in vitro, both proteins interact specifically with eEF-2, with a higher affinity for P1 (Kd = 3.8 x 10-8 m) than for P2 (Kd = 2.2 x 10-6 m). Phosphorylation resulted in a moderate increase (two- to four-fold) in these affinities. The interaction of both P1 and P2 (phosphorylated or not) with eEF-2 resulted in a conformational change in the factor, revealed by an increase in the accessibility of Glu554 to proteinase Glu-C. This increase was observed in both the presence and absence of GTP and GDP, which themselves produced marked opposite effects on the conformation of eEF-2. Our results suggest that the two proteins P1 and P2 both interact with eEF-2 inducing a conformational transition of the factor, but have acquired some specific properties during evolution.The eukaryotic P1 and P2 ribosomal proteins which constitute, with P0, a pentamer forming the lateral stalk of the 60 S ribosomal subunit, exhibit several differences from their prokaryotic equivalents L7 and L12; in particular, P1 does not have the same primary structure as P2 and both of them are phosphorylated, the significance of the latter remaining unclear. Rat liver P1 and P2 were overproduced in Escherichia coli cells and their interaction with elongation factor eEF-2 was studied. Both recombinant proteins were found to be required for the ribosome-dependent GTPase activity of eEF-2, with P2 in the phosphorylated form. The surface plasmon resonance technique revealed that, in vitro, both proteins interact specifically with eEF-2, with a higher affinity for P1 (Kd = 3.8 x 10-8 m) than for P2 (Kd = 2.2 x 10-6 m). Phosphorylation resulted in a moderate increase (two- to four-fold) in these affinities. The interaction of both P1 and P2 (phosphorylated or not) with eEF-2 resulted in a conformational change in the factor, revealed by an increase in the accessibility of Glu554 to proteinase Glu-C. This increase was observed in both the presence and absence of GTP and GDP, which themselves produced marked opposite effects on the conformation of eEF-2. Our results suggest that the two proteins P1 and P2 both interact with eEF-2 inducing a conformational transition of the factor, but have acquired some specific properties during evolution

    HIGH TEMPERATURE SUPERCONDUCTIVITY IN Bi-Sm-Sr-Ca-Cu-O

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    X-ray diffraction, resistivity and magnetic susceptibility for BiSrCaCuO (2224) system and 10 % Sm substituted for Bi in (2223) system are reported. The high temperature transition at 110 K disappears when Sm is substituted while there is no major change in the lattice parameters. The possible role of Bi-O planes in the superconducting mechanism in this system is indicated
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