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  • 1
    Digitale Medien
    Digitale Medien
    Stochastic difference equations for a spin system (1985)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 26 (1985), S. 692-697 
    Details
    ISSN: 1089-7658
    Quelle: AIP Digital Archive
    Thema: Mathematik , Physik
    Notizen: An N-spin model is given with a discrete-time evolution specified by a system of stochastic difference equations. A Markov chain associated with the evolution is decomposed into two, nonhomogeneous, absorbing Markov chains. Analysis of each chain yields the probability, given a specific initial state, of ultimate absorption into a specific state. As time t→∞ the spin model will, with probability equal to 1, have all spins up, all spins down, or will oscillate between two antiferromagnetic (Néel) states. The time-dependent correlation functions 〈si(t)sj(t)〉 are also obtained.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.526608
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  • 2
    Digitale Medien
    Digitale Medien
    Chromoplasts of Tropaeolum majus L.: Lipid synthesis in whole organelles and subfractions (1978)
    Springer
    Planta 141 (1978), S. 303-309 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Acyl-CoA hydrolase ; Acyltransferase ; Chromoplasts ; Galactosyltransferase ; Tropaeolum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Isolation of tubulous chromoplasts from Tropaeolum majus L. petals was achieved in pure form. Their main substructures-lipid bodies, tubules, and envelope membranes-have been enriched. Whole chromoplasts as well as substructures have been tested for their activities in lipid synthesis. The following activities were found: fatty acid synthesis from acetate, glycosyl transfer reactions from UDP-galactose and UDP-glucose to galactolipids and sterols, acyltransferase reactions from palmitoyl-CoA, and a very active acyl-CoA hydrolase (EC 3.1.2.2.). Fatty acid synthesis was restricted to whole chromoplasts. Glycosyl- and acyltransferases were essentially confined to envelope membranes, whereas acyl-CoA hydrolase was found in all fractions. The chemical composition of chromoplast subfractions was determined. The lipid bodies consisted mainly of galactolipids and carotenoid esters in a 1:1 ratio, together with small amounts of protein.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00388348
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  • 3
    Digitale Medien
    Digitale Medien
    Phytochrome-mediated transformation of glyoxysomes into peroxisomes in the cotyledons of mustard (Sinapis alba L.) seedlings (1976)
    Springer
    Planta 133 (1976), S. 73-80 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Organelle transformation ; Glyoxysomes ; Peroxisomes ; Phytochrome ; Sinapis alba
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The specific changes in the temporal pattern of glyoxysomal and peroxisomal enzymes in dark-grown and continuously far-red irradiated mustard seedlings are accompanied by specific changes in the spatial associations of microbodies with other cell organelles which can be quantitatively estimated from electron micrographs. The association (surface contact) with oleosomes (lipid bodies) and with plastids have been used as operational criteria for the glyoxysomal and peroxisomal engagement, respectively, of individual microbodies. The time course of these specific associations during the phytochrome-mediated changeover from glyoxysomal to peroxisomal character reveals the transient formation of functionally intermediary microbodies (“glyoxyperoxisomes”) which are associated to oleosomes as well as to plastids. In continuous far-red light, up to 50% of the microbody profiles detectable on electron micrographs fall into this category, compared to about 10% in darkness. It is concluded that peroxisomes of cotyledons neither originate de novo as an independent population nor are formed from pre-existing glyoxysomes by repackaging of enzymes. We suggest rather that a transition from glyoxysomal to peroxisomal enzyme formation in the presence of continuous turnover of microbody particles leads to a gradual replacement of microbodies of glyoxysomal character by microbodies of intermediary character and ultimately by microbodies of peroxisomal character.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00386008
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  • 4
    Digitale Medien
    Digitale Medien
    Phytochrome-mediated development of mitochondria in the cotyledons of mustard (Sinapis alba L.) seedlings (1976)
    Springer
    Planta 131 (1976), S. 253-261 
    Details
    ISSN: 1432-2048
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The development of mitochondria from promitochondria is regulated by phytochrome. This conclusion is based on four lines of evidence: 1. The activity of representative mitochondrial marker enzymes (fumarase, EC 4.2.1.2; succinate dehydrogenase, EC 1.3.99.1; cytochrome oxidase, EC 1.9.3.1) is increased by continuous far-red light and (in 2 of the 3 enzymes) by brief red pulses, the effect of which is reversible by brief far-red pulses. These effects do not merely represent a general growth or proliferation of mitochondria already present but specific responses of individual enzymes. Inhibitors of protein synthesis but not of RNA synthesis suppress the increase of these enzyme activities. 2. Continuous far-red light changes some structural properties of the mitochondrial membranes, detectable by an increased requirement of detergent (Triton X-100) for the solubilization of cytochrome oxidase and a more efficient retainment of the matrix enzyme fumarase during isolation of mitochondria. Continuous far-red light increases the apparent buoyant density of mitochondria on a sucrose density gradient. 3. Continuous far-red light has a strong effect on the morphology of the inner mitochondrial membrane system. Electron micrographs from dark-grown cotyledons show arrays of parallel, plate-like cristae while typical plant mitochondria with irregularly oriented sacculi are formed in the light. These responses indicate the involvement of mitochondria in cytophotomorphogenesis during the transition of the cotyledons from dissimilatory to assimilatory metabolism.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00385423
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  • 5
    Digitale Medien
    Digitale Medien
    Structure, composition, and distribution of plastid nucleoids in Narcissus pseudonarcissus (1985)
    Springer
    Planta 164 (1985), S. 459-472 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Chloroplast (nucleoid) ; Chromoplast (nucleoid) ; Narcissus ; Plastid (envelope, DNA)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The size, frequency and distribution of the nucleoids of chloroplasts (cl-nucleoids) and chromoplasts (cr-nucleoids) of the daffodil have been investigated in situ using the DNA-specific fluorochrome 4′6-diamidino-2-phenylindole. Chromoplasts contain fewer nucleoids (approx. 4) than chloroplasts (〉 10), and larger chromoplasts (cultivated form, approx. 4) contain more than smaller ones (wild type, approx. 2). During chromoplast development the nucleoid number decreases in parallel with the chlorophyll content. Each nucleoid contains 2–3 plastome copies on average. In chloroplasts the nucleoids are evenly distributed, whereas they are peripherally located in chromoplasts. The fine structure of isolated cl-and cr-nucleoids, purified either by Sepharose 4B-CL columns or by metrizamide gradients, was investigated electron microscopically. The cl-nucleoids consist of a central protein-rich core with ‘naked’ DNA-loops protruding from it. In cr-nucleoids, on the other hand, the total DNA is tightly packed within the proteinaceous core. The protein-containing core region of the nucleoids is made up of knotty and fibrillar sub-structures with diameters of 18 and 37 nm, respectively. After proteinase treatment, or incressing ion concentration, most of the proteins are removed and the DNA is exposed even in the case of cr-nucleoids, the stability of which proved to be greater than that of cl-nucleoids. The chemical composition of isolated plastid nucleoids has been determined qualitatively and quantitatively. Chromoplast-nucleoids contain, relative to the same DNA quantity, about six times as much protein as cl-nucleoids. Accordingly the buoyant density of cr-nucleoids in metrizamide gradients is higher than that of cl-nucleoids. In addition to DNA and protein, RNA could be found in the nucleoid fraction. No pigments were present. The cr-and cl-nucleoids have many identical proteins. There are, however, also characteristic differences in their protein pattern which are possibly related to the different expression of the genomes of chloroplasts and chromoplasts. Nucleoids of both plastid types contain some proteins which also occur in isolated envelope membranes (probably partly in the outer membrane) and thus possibly take part in binding the DNA to membranes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00395961
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  • 6
    Digitale Medien
    Digitale Medien
    Comparative studies on the structure proteins of T3 and T7 phages (1976)
    Springer
    Archives of virology 52 (1976), S. 217-231 
    Details
    ISSN: 1432-8798
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A comparison of the coat protein patterns of the wild types of the related phages T3 and T7 on SDS polyacrylamide gel electrophoresis was carried out. After infection of the nonpermissive host with T7 amber mutants in genes 7, 11, 12, 13 or 17 and T3 amber mutants in genes 11, 12, 13 and 17 respectively, noninfectious, DNA containing particles were produced. The protein pattern, as well as electron microscopy of defective particles of T3 and T7 led to the conclusion that the proteins specified by genes 11, 12, 13 and 17 are tail proteins whereas the proteins coded by genes 7, 8, 10, 14, 15 and 16 enter the head structure. The “serum blocking protein” (gene 17 product) seems to play a different role in the assembly of T3 and T7 tails, since T3 particles defective in gene 17 did not show any tail structure connected with the head whereas T7 particles defective in gene 17 had a tail which looked different from that of the wildtype. Treatment of wildtype particles with ammonium nitrate or sodium pyrophosphate led to morphologically abberrant forms which had partially or completely lost the hexagonal head structure. After treatment with ammonium nitrate balllike structures were obtained, both for T3 and T7. However, in the case of T3 these abberrant forms contained the proteins specified by genes 7, 8 and 10 whereas those derived from T7 contained only the proteins specified by genes 8 and 10. Sodium pyrophosphate treatment of T3 and T7 wildtype particles led to a release of the phage tails. The isolated tails were examined by electron microscopy thus revealing for the first time a detailed substructure of the T3 and T7 phage tails. In order to find out more about the tail proteins, adsorption experiments with isolated bacterial cell walls were carried out.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01348019
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  • 7
    Digitale Medien
    Digitale Medien
    Correlation between serum and adipose tissue levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin in 50 persons from Missouri (1988)
    Springer
    Archives of environmental contamination and toxicology 17 (1988), S. 139-143 
    Details
    ISSN: 1432-0703
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik , Medizin
    Notizen: Abstract Paired human serum and adipose tissue samples were analyzed from 50 persons for 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) by high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS). On a lipid weight basis, the range of values in adipose tissue spanned approximately 2.5 orders of magnitude, from 3.3 to 969 parts per trillion (ppt). After adjusting the adipose tissue 2,3,7,8-TCDD levels for total lipid content and the serum 2,3,7,8-TCDD levels for total lipid content, the mean of the partitioning ratio of adipose tissue to serum 2,3,7,8-TCDD was 1.09 (standard deviation = 0.385, standard error = 0.060). On this same total lipid weight basis, the adipose tissue and serum levels of 2,3,7,8-TCDD were highly correlated, r = 0.98. The high correlation between adipose tissue and serum 2,3,7,8-TCDD levels in this study indicates that serum 2,3,7,8-TCDD is a valid measurement of 2,3,7,8-TCDD body burden concentration.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01056017
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  • 8
    Digitale Medien
    Digitale Medien
    Appearence and localization of a β-glucosidase hydrolyzing coniferin in spruce (Picea abies) seedlings (1979)
    Springer
    Planta 144 (1979), S. 161-165 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Coniferin ; β-Glucosidase ; Immunofluorescent studies ; Lignification ; Picea
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract β-Glucosidase activity for coniferin (coniferyl alcohol β-D-glucoside) is not present in spruce (Picea abies L. Karst.) seeds but appears in the young seedlings. Lignification starts at ca. day 9 of germination in the vascular bundles. An antiserum against glucosidase 1 isolated from spruce seedlings (Marcinowski and Grisebach, Eur J. Biochem. 1978) was employed for the localization of the enzyme in cross sections of hypocotyls using immunofluorescent technique. The results indicate that at this stage of development the glucosidase is localized at the inner layer of the secondary cell wall. Glucosidase activity was present in all cells of the investigated hypocotyl tissue.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00387265
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  • 9
    Digitale Medien
    Digitale Medien
    Chromoplasts of Tropaeolum majus L.: Isolation and characterization of lipoprotein elements (1976)
    Springer
    Planta 128 (1976), S. 23-28 
    Details
    ISSN: 1432-2048
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Chromoplasts of unfolding petals of Tropaeolum majus contain large amounts of filaments (which, in sections, appear as tubules), and unevenshaped, isodiametric to elongated bodies (IBs). These structural elements are the major sites of the chromoplast pigments. They were freed from isolated chromoplasts and subjected to sucrose density gradient centrifugation. At a density of 1.080 g cm-3 a distinct orange band contained almost exclusively fine filaments of 15–20 nm in diameter as shown after negative staining. Other filaments and most of the IBs were heterogeneous in size, shape, and density and were collected in two fractions of buoyant densities of 1.025 and 1.055 g cm-3. The three fractions thus obtained comprise 15–33% protein, large amounts of carotenoids and their esters, glyco- and phospholipids, as well as minor amounts of tocopherols. A higher buoyant density of particles is correlated with a higher relative content of protein and glyco- and phospholipids and a lower relative content of carotenoids. The polypeptide pattern, as shown by SDS-polyacrylamide gel electrophoresis, is very similar in all three fractions. There is one main polypeptide, with a MW of about 30,000, accounting for up to 80% of the protein of each fraction.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00397174
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  • 10
    Digitale Medien
    Digitale Medien
    Beiträge zur Chemie der Pyrrolpigmente, 9. Mitt.: Bildung, Struktur und Konfiguration vonZ- undE-Arylmethyliden-3,4-dimethyl-3-pyrrolin-2-onen (1975)
    Springer
    Monatshefte für Chemie 106 (1975), S. 301-312 
    Details
    ISSN: 1434-4475
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The condensation of 3.4-dimethyl-3-pyrrolin-2-one with p-methyl-, p-chloro-benzaldehyde and ferrocenealdehyde yields theZ-andE-isomers of the corresponding condensates. Due to kinetic control theZ-isomers are obtained almost exclusively in this reaction. TheE-isomers of the two firstmentioned products can be produced by photochemical isomerization. The structures (tautomeric forms) and configurations of the isomers were established by the Lanthanide-induced-shift-technique and by evaluating the Nuclear-Overhauser-Effect.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00914522
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