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  • Rat  (13)
  • Prebiotic  (6)
  • Springer  (19)
  • 2020-2024
  • 2010-2014
  • 1970-1974  (19)
  • 1945-1949
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  • Springer  (19)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 2 (1973), S. 231-234 
    ISSN: 1432-1432
    Keywords: Phosphorylation ; Nucleotides ; Nucleoside Polyphosphates ; Oligonucleotides ; Urea ; Prebiotic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have analyzed the products formed when mixtures of a nucleoside and ammonium dihydrogen phosphate are heated with an excess of urea. If there is more phosphate than nucleoside in the mixture, compounds containing pyrophosphate bonds are obtained. If uridine, as nucleoside, is in excess over phosphate, di- and oligonucleotides are formed.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 1 (1972), S. 249-257 
    ISSN: 1432-1432
    Keywords: Prebiotic ; Nucleosides ; Dry-phase ; Seawater
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The purine nucleosides (adenosine, guanosine, inosine, xanthosine) are formed when the corresponding purine bases and D-ribose are heated together in the presence of certain salts and minerals. The salts remaining after the evaporation of seawater are particularly effective in these syntheses. The relevance of these reactions for prebiological evolution is discussed.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 3 (1974), S. 141-150 
    ISSN: 1432-1432
    Keywords: Adsorption ; Clay ; Montmorillonite ; Phosphoramidates ; Polymerization ; Prebiotic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Nucleoside phosphoramidates derived from polyamines containing at least three amine groups are strongly adsorbed by sodium and magnesium montmorillonite clays even from very dilute solutions. Heating the dried clay-phosphoramidate mixture results in the production of small amounts of the dinucleotides.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 2 (1973), S. 303-316 
    ISSN: 1432-1432
    Keywords: Polymerization ; Phosphorylation ; Adenosine Cyclic 2′,3′-phosphate ; Oligonucleotides ; Amines ; 2-Aminoethanol ; Amino Acids ; Prebiotic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary When adenosine cyclic 2′,3′-phosphate is evaporated from solution in the presence of simple catalysts such as aliphatic diamines at alkaline pH, and maintained in a dry state at moderate temperatures (25-85°C), self-polymerization to give oligonucleotides of chainlength up to at least 6 is observed. The products contain an excess of [3′→5′]-linkages over [2′→5′]-linkages. The effects of different catalysts and reaction conditions on the efficiency of the reaction are described. The prebiological relevance of these reactions is discussed.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 3 (1974), S. 317-321 
    ISSN: 1432-1432
    Keywords: Thiophosphate ; Thymidine ; Phosphorylation of Nucleosides ; Prebiotic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary It is proposed that inorganic thiophosphate was a versatile and highly reactive constituent of the primitive earth. Some of the ramifications of this assumption with regard to prebiotic chemistry stem from the dual nature of thiophosphate as the most superior nucleophilic agent and an energy rich phosphate. The Michael addition of thiophosphate to acrylonitrile yieldsS-cyanoethylphosphorothioate in high yield. This compound in turn can be used to phosphorylate 2′-deoxythymidine in organic solvents and in the solid state. A mixture of 5′ and 3′-dTMP were identified via chromatography, elementary analysis and NMR spectroscopy.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 1 (1972), S. 241-248 
    ISSN: 1432-1432
    Keywords: Urea ; Ammonium Dihydrogen Phosphate ; Nucleoside ; Prebiotic ; Polyphosphate ; Trimetaphosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary When ammonium dihydrogen phosphate is heated with urea to temperatures in the range 85–100°C, it polymerizes almost quantitatively to give polyphosphates containing, on the average, more than ten (PO3) residues. Similar experiments carried out at 72°C give polyphosphate in more than 60% yield. If a nucleoside (thymidine or 3′-deoxythymidine) is added to the reaction mixture, up to 23% of trimetaphosphate can be obtained at 100°C. The prebiotic significance of these reactions is discussed.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 14 (1974), S. 283-289 
    ISSN: 1432-0827
    Keywords: Sodium fluoride ; Osteoporosis ; Bone ; Strength ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'utilisation thérapeutique de fluorure de sodium a été recommandée dans le traitement de diverses maladies osseuses ostéopéniques. Cet emploi est basé principalement sur les effects ostéosclérotiques bien connus du fluorure de sodium, mais on connait mal son effet sur la force de résistance osseuse. L'influence de diverses concentrations de fluorure de sodium sur la force de résistance osseuse de jeunes rats soumis à des régimes riches et pauvres en calcium a été étudiée. L'administration de fluorure de sodium augmente le diamètre osseux, indiquant une stimulation de la formation de l'os périosté, mais la force de résistance osseuse est réduite ou non modifiée par l'ingestion de fluor.
    Abstract: Zusammenfassung Die therapeutische Verwendung von Natriumfluorid ist für eine Anzahl von Knochenmangel-Krankheiten empfohlen worden. Die Empfehlungen basieren hauptsächlich auf den bekannten osteosklerotischen Wirkungen von Natriumfluorid; über dessen Effekt auf die Knochenstärke ist wenig bekannt. In dieser Arbeit wurde der Einfluß verschiedener Konzentrationen von Natriumfluorid auf die Knochenstärken von wachsenden Ratten mit hoher und niederer Calciumeinnahme untersucht. Die Verabreichung von Natriumfluorid erhöhte den Knochendurchmesser, was auf eine Stimulierung der Periostbildung hinwies, die Knochenstärke wurde jedoch durch Fluorideinnahme herabgesetzt oder nicht beeinflußt.
    Notes: Abstract The therapeutic use of sodium fluoride has been recommended in a variety of osteopenic bone diseases. The recommendations are based mainly on the known osteosclerotic effects of sodium fluoride and little information is available as to its effect on bone strength. The influence of various concentrations of sodium fluoride on bone strength in growing rats on high and low calcium diets was studied. The administration of sodium fluoride increased bone diameter, indicating stimulation of periosteal bone formation, but bone strength was reduced or not affected by fluoride ingestion.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 110 (1970), S. 97-107 
    ISSN: 1432-0878
    Keywords: Muscle Spindles ; Different types of sensory endings ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung In einer Muskelspindel der Ratte, die an einer Serie alternierender Semidünn- und Ultradünnquerschnitte untersucht wurde, wurden zwei benachbart an „nuclear chain“-Fasern gelegene Nervenendformationen unterschiedlicher Bauweise festgestellt. Die beiden Endformationen sind mit ein und derselben Nervenfaser der Gruppe II verbunden und daher als Bestandteile einer sekundären sensorischen Endigung zu betrachten. Die Nervenendformation an einer der beiden „nuclear chain“-Fasern hat anulo-spirale Form. Die Nervenendformation an der anderen „nuclear chain“-Faser weist am Querschnittsbild eine Anzahl von Axonen auf, die zwischen Plasmalemm und Basalmembran der intrafusalen Muskelfaser eng aneinanderliegen. Nicht alle Axonquerschnitte stehen in direktem Kontakt mit der intrafusalen Faser. Das terminale Axon scheint sieh nach Eintritt unter die Basalmembran der intrafusalen Faser mehrfach in relativ dünne Äste unregelmäßigen Verlaufs zu teilen. Diese Form der Endigung könnte ein Korrelat der sog. „flower spray“-Endigung im Sinne Ruffinis (1898) darstellen. Die beiden morphologisch unterschiedlichen Endformationen innerhalb der sekundären Endigung gleichen einander und den Endformationen der primären Endigung bezüglich folgender Ultrastrukturmerkmale: 1. Es besteht synaptischer Kontakt zwischen Axon und intrafusaler Muskelfaser (synaptischer Spalt durchschnittlich 200 Å) ohne Zwischenlagerung von Basalmembranmaterial; 2. die terminalen Axonabschnitte liegen direkt unter der Basalmembran der intrafusalen Muskelfaser und sind nicht von Schwannschen Zellen bedeckt; 3. Mangel an synaptischen Bläschen; 4. desmosomenartige Verhaftungen zwischen Zellmembranen von Axon und intrafusaler Faser; 5. dyadenartige Anlagerungen des sarkoplasmatischen Retikulums an die Zellmembran der intrafusalen Faser im Bereich des synaptischen Spaltes. Nach unseren derzeitigen Vorstellungen sprechen diese Ultrastrukturmerkmale für eine rezeptorische Natur der beschriebenen Nervenendigungen.
    Notes: Summary In a rat muscle spindle transversally cut into a series of alternating semithin and ultrathin sections, two different forms of nerve terminations were found on two neighbouring nuclear chain fibres. The two nerve terminations were connected to the same group II nerve fibre and are consequently constituents of one particular secondary sensory ending. The nerve termination on one of the two nuclear chain fibres is of the anulo-spiral type. The nerve termination on the second nuclear chain fibre shows a number of axons lying closely together between plasma membrane and basement membrane of the intrafusal muscle fibre. Not all of these axons are in direct contact with the intrafusal fibre. The terminating nerve fibre seems to be divided into several branches of rather small diameters and irregular courses. It is suggested that this kind of termination could be a correlate of the so-called “flower spray” type of sensory endings in muscle spindles. The two morphologically different nerve terminations in the secondary ending have the following ultrastructural characteristics in common with those of the primary ending: 1) Synaptic contact between axon and intrafusal muscle fibre (synaptic gap about 200 Å) without interposition of basement membrane material; 2) terminal axons located beneath the basement membrane layer of intrafusal muscle fibres without covering by Schwann cells; 3) lack of synaptic vesicles; 4) desmosome-like structures between plasma membranes of axon and intrafusal muscle fibre, and 5) dyads of the sarcoplasmic reticulum adjacent to the synaptic cleft. According to present knowledge these features indicate that all of these endings are sensory ones.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 131 (1972), S. 99-107 
    ISSN: 1432-0878
    Keywords: Median eminence ; Rat ; Exocytosis ; Micro-pinocytosis ; Releasing factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Exocytosis has been demonstrated by electron microscopy in the external zone of the median eminence of the rat. Exocytotic profiles have been observed in nerve fibres characterized by the presence of granular vesicles with median diameters of 90–103 nm and agranular vesicles of about 50 nm. In addition to the small agranular vesicles, coated vesicles of the same size have been found in many nerve fibres, suggesting that at least part of the agranular vesicles in the median eminence originate by micro-pinocytosis. The nature of the fibres showing exocytosis is discussed. Attention is drawn to the possibility of identifying types of fibres in the median eminence by the occurrence of exocytosis.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 136 (1973), S. 111-120 
    ISSN: 1432-0878
    Keywords: Median eminence ; Rat ; Granular vesicles ; Ultrastructure ; Quantitative evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In order to characterize different sub-zones in the palisade zone of the rat median eminence, quantitative ultrastructural parameters were applied to brains fixed in aldehyde-osmium tetroxide. The palisade zone has been subdivided in 4 successive sub-zones. Increasing numbers of granular vesicles (GV), especially those smaller than 110 nm, are observed from dorsal to ventral sub-zones. There also are more GV per unit area of nervous tissue in the perivascular than in the more dorsal sub-zones. The individual nerve profiles exhibit a larger size in the perivascular layer than in the more dorsal areas, whereas the number and size of nerve profiles devoid of vesicles diminish from dorsal to ventral. As a consequence more GV occur in the perivascular nerve profiles. In the GV containing nerve profiles the concentration of GV is, however, constant in the different sub-zones. A fluctuating size of the preterminal and terminal parts of the nerve fibres is suggested.
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