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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Analytical chemistry 56 (1984), S. 1422-1428 
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-041X
    Keywords: Salivary gland ; Protein synthesis ; Larval development ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Patterns of protein synthesis in the salivary glands ofDrosophila melanogaster have been studied throughout late larval and prepupal development by pulse labelling the tissues with35S-methionine. Specific changes to the pattern of proteins synthesized during development are found and the significance of these changes is discussed in view of the known changes in gene (puffing) activity which occur at the same times. We review the problem of salivary gland function in “prepupal”Drosophila.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 193 (1984), S. 205-210 
    ISSN: 1432-041X
    Keywords: Rat early embryo ; Regionalization ; Polarization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In rat pre-implantation embryos, we compared the polarization of cytoplasmic organelles with cell membrane regionalization as revealed by the cytochemical demonstration of 5′-nucleotidase and alkaline phosphatase. The polarization is shown at the eight-cell stage by columns of organelles extending from the nuclei to the embryo periphery. No consistent segregation of cytoplasmic components was recognized prior to the eight-cell stage. As to regionalization, both enzyme activities were demonstrated, from the late four-cell stage onwards on the cell surface between blastomeres of early and late morulae, while the external surface of the embryo lacked these activities. In early blastocysts, these enzyme activities were lost on the inner surface of the blastocyst cavity and in late blastocysts; 5′-nucleotidase activity appeared on the external surface of the embryonal trophoplast and extended to the abembryonal pole. From these observations we conclude that cell membrane regionalization precedes the polarization of the cytoplasm; however, this temporal relationship does not necessarily imply a causal relationship, since both phenomena may be independent expressions of an underlying morphonetic process.
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  • 4
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have isolated by molecular cloning techniques a structural gene that maps to subregion 63 F of Drosophila melanogaster chromosome 3L. This locus being one of the early chromosomal targets for ecdysone stimulation, may be induced to puff by the hormone. The gene is on a plasmid vector and it has been designated as pDm 63F. This recombinant molecule also maps to the early ecdysone inducible subregion 90B of Drosophila hydei chromosome 4. The cytological inspection of large number of chromosomal sets after in situ hybridization of the cloned DNA, locates the cloned sequence between bands 63F 2–4 according to Bridges map. Similarly, in Drosophila hydei the cloned DNA maps between subdivisions 90B 2–4 according to Berendes’ map. In situ hybridization of the pDm 63F cloned DNA, directed to the nascent RNA rather than to the DNA, shows two to three times more silver grains over the corresponding regions when puffed than in the resting stage. There are however quantitative differences attending to the transcriptional activity of homologous loci in both species. By RNA excess hybridization we have found that the cellular concentration of the 63F cloned mRNA is about 2 times higher in hormone stimulated total larval tissues than in non-stimulated ones.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 36 (1980), S. 539-540 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Shuttle avoidance training decreased the cAMP content of rat brain (excluding hippocampus and caudate nucleus), amygdala and hypothalamus. Stimulation by tones alone had a similar effect, but only in the brain fraction. Pseudoconditioning or footshocks alone had no effect.
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  • 6
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR - As scientists working in Chile, we value the concern that Nature has shown for the state of academic life under Chile's dictatorial regime in publishing Simon Litvak's commentary (Nature 306, 11; 1984). We share Litvak's criticism of the ways in which Chilean universities have been abused for ...
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 285 (1980), S. 674-676 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] To isolate segments of D. melanogaster DNA containing ribosomal protein (r-protein) genes we purified a probe enriched for r-protein mRNA and hybridized a cDNA copy of it to a D. melanogaster genomic library contained in the ?-derived cloning vector Charon 4. Previous work has demonstrated that ...
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  • 8
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The induction and distribution of chromosomal transcripts in the polytene chromosomes of D. melanogaster and D. hydei has been investigated by indirect immunofluorescence using an antiserum directed against DNA/RNA hybrids. The fluorescence was intense and occurred in most of the chromosomal subdivisions when the chromosomes were exposed to denaturing conditions and then allowed to reanneal. The extent of hybrid formation depended both on the extent of DNA denaturation and on the maintenance of RNA integrity. Fluorescence was absent from chromosomes treated with pancreatic RNase before denaturation. The velocity of the chromosomal DNA/RNA hybridization reaction and the effects of the initiation inhibitor of RNA synthesis, DRB, suggest that in order to hybridize the RNA has to be located in its transcriptional compartment. Even though overall patterns of fluorescence seem to be similar during a developmental stage, variations were observed, particularly some correlated with puff induction after ecdysone stimulation.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Microchimica acta 79 (1983), S. 371-380 
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Verteilung von 5,7-Dichlor-2-methyl-8-hydroxychinolin bei 25±0.1° C und Ionenstärke 0,1 wurde in Abhängigkeit von dem pH-Wert in den Systemen Wasser-Benzol, Wasser-n-Hexan, Wasser-Chloroform und Wasser-Isoamylalkohol untersucht. Die Dissoziations- und die Verteilungskonstanten wurden aus den Ergebnissen der Untersuchung der Verteilung berechnet. Ihre Werte stehen mit der Dielektrizitätskonstante der organischen Lösungsmittel und mit der Wirkung der Substituenten in Verbindung. Auch der Einfluß der Art und der Konzentration der Elektrolyte auf denK D-Wert wurde bestimmt. Schließlich wurde die Löslichkeit des Reagens in den erwähnten Lösungsmitteln bestimmt und die gute Übereinstimmung zwischen den Werten des VerhältnissesS o /S W und der KonstantenK D festgestellt.
    Notes: Summary The distribution of 5,7-dichloro-2-rnethyl-8-hydroxyquinoline, at 25.0±0.1° C and 0.1 ionic strength, has been studied for the systemsn-hexane-water, benzene-water, chloroform-water and isoamyl alcohol-water. From the distribution data, the dissociation and distribution constants of the reagent have been calculated. The effects of the dielectric constant of the solvent, the substituents and the nature and concentration of electrolytes onK D have also been determined. The solubilities of the reagent in the solvents studied have been determined and good agreement found betweenS O /S W andK D.
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  • 10
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammmenfassung Das Verteilungsgleichgewicht von 3-Phenyl-3-methyl-2-mercaptopropensäure (PhMMP), Pyridin und Titan-PhMMP-Komplex in Gegenwart von Pyridin wurde in einem Wasser-Chloroform-System untersucht. Eine extraktionsphotometrische Methode für die Bestimmung von Mikromengen Titan(IV) wurde ausgearbeitet. Die synergistische Wirkung des Pyridins sowie der Einfluß des pH, des Reagens und der Gegenwart von Elektrolyten und maskierenden Reagenzien in der wäßrigen Phase auf das Gleichgewicht wurden bestimmt. Aus der Richtung der Verteilungskurven wurde für den extrahierten Komplex die Zusammensetzung Ti(OH)2(HR)2·py ermittelt. Der Komplex wird quantitativ extrahiert. Das Beersche Gesetz ist von 0,09–4,30μg·ml−1 Ti(IV) erfüllt, der molare Absorptionskoeffizient ist 1,13·1041·mol−1·cm−1; die Sandell-Empfindlichkeit beträgt 3,7ng·cm−2 bei 447 nm. Diese Methode wurde für die Bestimmung von Titan in keramischem Material verwendet.
    Notes: Summary The distribution equilibria of 3-phenyl-3-methyl-2-mercaptopropenoic acid (PhMMP), pyridine and the titanium (IV)-PhMMP complex in the presence of pyridine have been studied in the chloroform-water system. An extraction-photometric method for the determination of micro amounts of titanium has been developed. The synergistic effect of pyridine, and the influence of pH, the reagent concentration and the presence of electrolytes and masking agents on the equilibrium have been determined. From slope analysis of the distribution curves, the composition of the extracted species has been found to be Ti(OH)2(HR)2·py. The complex is extracted quantitatively. Beer's law is obeyed over the range 0.09–4.30μg/ml titanium (IV) and the molar absorptivity is 1.30×1041·mole−1·cm−1 at 447 nm. The method has been applied to the determination of titanium in ceramics.
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