Showing papers by "Martin Luther University of Halle-Wittenberg published in 1979"

Cytoplasmic synthesis of plastid polypeptides may be controlled by plastid-synthesised RNA

Abstract: IT is generally agreed that some plastid polypeptides are coded by plastid DNA and the remainder by nuclear DNA, and that some plastid polypeptides are synthesised on plastid ribosomes and the remainder on cytoplasmic ribosomes1,2. Studies on two mutant lines of barley (Hordeum vulgare L. ‘albostrians’ (M4205) and ‘Saskatoon’) have helped the understanding of the integration of the plastid and nucleocytoplasmic systems. In both lines a nuclear mutation is expressed as an irreversible mutation of the plastid DNA yielding pigment-deficient plastids whose segregation leads to white-striped leaves and later to pure white leaves and shoots3,4. The white leaves do not contain plastid ribosomes and no protein synthesis can be detected in the plastids, although cytoplasmic ribosomes are present in normal amounts5,6. Immunoelectrophoresis of extracts of white leaves has failed to detect either the plastid-synthesised large subunit or the cytoplasmically synthesised small subunit of ribulose-bisphosphate carboxylase/oxygenase, or coupling factor CF1, which has three plastid-synthesised and two cytoplasmically synthesised subunits, or the cytoplasmically synthesised ferredoxin-NADP+ reductase6,7. We report here that two cytoplasmically synthesised plastid enzymes8, phosphoribulokinase (EC 2.7.1.19) and D-glyceraldehyde-3-phosphate: NADP+ oxidoreductase (phosphorylating) (EC 1.2.1.13), occur in considerably reduced amounts in white leaves and deduce how the plastid may control the cytoplasmic synthesis of plastid polypeptides.

Pharmacokinetic model based on circulatory transport

Abstract: Assessment of pharmacokinetics in terms of circulatory drug transport is proposed using the methods of linear system theory. In this model-independent approach drug distribution and disposition are characterized by the total extraction ratio, the mean residence time in the body and the volume of distribution at steady state. In analyzing concentration(c)-time(t) data, the procedure requires calculation only of the areas under the c(t)-and c(t)×t-curves to estimate kinetic parameters, and for prediction of the steady state concentration following continuous infusion or multiple doses. Pulmonary clearance of drugs is included in the theory.

Tilt Angle Determination of a Smectic C Phase by Field-Induced Freedericksz Transition and x ray Investigations

Abstract: A smectic C liquid crystal exhibiting positive dielectric anisotropy was oriented with the director parallel to the glass substrates. When an electric field was applied normal to the director direction a dielectric reorientation (Freedericksz transition) occurred. Dissolving a dichroic dye in the smectic C phase and applying an electric field, a guest host effect similar to nematic phases was observed. From the dielectric reorientation the tilt angle of the smectic C phase was determined at different temperatures. The tilt angles obtained by the electrooptical measurements agree sufficiently with the values measured by x ray investigations.

Intracellular Protein Turnover

Abstract: In the first part of this short review we shall summarize some of the main characteristics of intracellular protein turnover, and in the second part we shall go on to describe some of our work on the molecular mechanisms responsible for the characteristics of this process in rat liver. But first we must define the processes that we are talking about.

Kristallin‐flüssige Thiazole

Abstract: Liquid Crystal Thiazoles The synthesis of 2,4- and 2,5-disubstituted thiazoles is described and their melting and clearing points are investigated. The influence of the thiazole ring system on the formation of crystalline-liquid phases is discussed.

Precipitation and dissolution processes in age-hardenable Al alloys — a comparison of positron annihilation and X-ray small-angle scattering investigations I. Al—Zn(x) (x = 3, 4.5, 6, 10, and 18 at%)

Abstract: The precipitation and dissolution processes going on during continuous heating (heating rate of 1 K/min) in four AlZn(4.5)–Mg(x) alloys are studied by means of XSAS, TEM, and PAS investigations. The XSAS and TEM investigations give strong evidence that only GP zones as well as η′-particles of overcritical size are transformed directly into the more stable phases during the heating procedure. GP zones and η′-particles of subcritical size are dissolved attaining their dissolution temperature and on the expense of this material the more stable phases are formed. The PAS results are very strongly influenced by the Mg additions which can be understood by the formation of VZnMg complexes. Most probably in case of the presence of zones the positrons are mainly trapped by monovacancies bound to Mg atoms inside the Zn-rich GP zones. Due to this special trapping effect the PAS is not in a direct and simple way related to the various precipitation processes going on in the AlZnMg alloy as known from the AlZn alloys. The formation of partially coherent and incoherent precipitates causes an increase of the h-parameter which can be understood by localization of positrons at parts of the incoherent particle-matrix interfaces of high-angle boundary type. Die in vier AlZn(4.5)Mg(x)-Legierungen wahrend kontinuierlichen Aufheizens (Aufheizrate 1 K/min) auftretenden Bildungs- und Auflosungsprozesse von Ausscheidungen werden mit Hilfe von RKWS-, TEM- und PAS-Messungen studiert. Die RKWS- und TEM-Messungen beweisen klar, das nur uberkritische GP-Zonen sowie η′-Partikel wahrend des Aufheizens direkt in die stabileren Partikel umgewandelt werden konnen. Unterkritische Ausscheidungen dieser Art werden nach Erreichen ihrer Auflosungstemperatur aufgelost, und aus diesem Material bilden sich dann die stabileren Ausscheidungen. Die PAS-Ergebnisse werden durch die Mg-Zugaben stark beeinflust. Dies kann durch die Bildung von MgZnV-Komplexen verstanden werden. Beim Vorhandensein von GP-Zonen werden die Positronen hochstwahrscheinlich hauptsachlich von Einzelleerstellen eingefangen, die an Mg-Atome innerhalb der Zn-reichen GP-Zonen gebunden sind. Dadurch ist in den AlZnMg-Legierungen das PAS nicht in einer direkten und einfachen Weise mit den verschiedenen Ausscheidungsprozessen verknupft wie das von den AlZn-Legierungen her bekannt ist. Die Bildung teil- und inkoharenter Ausscheidungen verursacht ein Ansteigen des h-Parameters. Dies kann durch Lokalisierung von Positronen an Teilen der inkoharenten Partikel-Matrix-Grenzflache vom Groswinkeltyp verstanden werden.

Anti-aggregatory effect of prostacyclin (PGI2) in vivo.

Abstract: Prostacyclin (PGI2) when infused intravenously reduced the mortality of rabbits given high intravenous doses of arachidonic acid (AA). Prostaglandins E1 and D2 were ineffective. Indomethacin pretreatment abolished the toxic AA effect. Since the lethal effect of AA is partly due to the formation of platelet aggregates it is concluded that PGI2 is a most potent anti-aggregatory prostaglandin in vivo.

Dielectric behaviour of ferroelastic monodomain TSCC crystals

Abstract: In earlier publications there are some differences on dielectric results on TSCC crystals. It is shown that these differences are due to ferroelastic properties of TSCC in the paraelectric phase. From the temperature dependence of the dielectric permittivity ϵb and the spontaneous polarization of ferroelastic monodomain specimens it can be concluded that the phase transition is of second order. Peculiarities of the hysteresis loops and the shift of the maximum of the dielectric permittivity when an electric bias field is applied on the specimen are discussed. In fruheren Veroffentlichungen gibt es einige unterschiedliche Ergebnisse bezuglich des dielektrischen Verhaltens von TSCC-Kristallen. Es wird gezeigt, das diese auf die Ferroelastizitat von TSCC in der paraelektrischen Phase zuruckzufuhren sind. An ferroelastisch eindomanigen Proben zeigen die Dielektrizitatskonstante und die spontane Polarisation ein Verhalten, das auf eine Phasenumwandlung zweiter Art schliesen last. Besonderheiten der Form der Hysteresekurve und der Verschiebung des Maximums der Dielektrizitatskonstante unter dem Einflus eines elektrischen Gleichfeldes werden diskutiert.

Synthese und Reaktionen von 2-[Bis-(alkylthio)-methyliden]-indan-1,3-dionen

Abstract: Synthesis and Reactions of 2-[Bis-(alkylthio)-methyliden]-indan-1,3-diones The 2-[bis-(alkylthio)-methyliden]-indan-1,3-diones 3 and especially the methyl-compound 3a react with nucleophiles by substitution of the CH3Sgroup. The reaction with amines are yields the S,N or N,N-acetales 7 and 8, respectively. Diamines, amino hydroxy- or amino-mercapto compounds as dinucleophiles give the cyclic compounds 9 or the condensed heterocycles 12 and 16, where the carbonyl group has been integrated in the cyclisation. Also carbanions react with 3a under substitution. The structures of the final products are determined with ir-, 1H-n.m.r.- and ms-spectra.

X‐ray diffraction in the Bragg case at Bragg angles of about π/2

Abstract: X-ray diffraction at Bragg angles of about π/2 is studied by the conventional and the extended dynamical theory. The diffraction patterns according to both the theories are exactly the same if the incidence parameter α of the conventional theory is corrected. In the symmetric Bragg case the maximum halfwidth of the diffraction pattern is given by belonging to a Bragg angle ·(χ0,χh are the Fourier coefficients of the susceptibility.) It is shown, that all results can be understood by considering the dispersion surface of the fourth-order secular equation in the nonabsorbing case. Die Rontgenstrahlbeugung bei Braggwinkeln nahe π/2 wird mit Hilfe der konventionellen und der erweiterten dynamischen Theorie untersucht. Die nach beiden Theorien erhaltenen Reflexionskurven stimmen exakt uberein, wenn der Einfallsparameter α der konventionellen Theorie korrigiert wird. Im symmetrischen Bragg-Fall wird bei der einstrahlseitigen geometrischen Braggposition von die fur die Reflexionskurven maximale Halbwertsbreite von erreicht. (χ0, χh sind die Fourier-Koeffizienten der Suszeptibilitat.) Es wird gezeigt, das alle Ergebnisse anhand der Betrachtung der Dispersionsflache der Sakulargleichung vierten Grades im nichtabsorbierenden Fall verstanden werden konnen.

Effects of herbicide treatment on the structure and functioning of agro-ecosystems II. Structural changes in the plant community after the application of herbicides over several years☆

Abstract: The paper reports the effects of the continued application of herbicides over 5 years on the structure of the plant community in a selected agro-ecosystem with cereals within the crop rotation. The application of herbicides led to quantitative changes in the structure of the weed population, both in the numbers of individuals and the development of biomass. In contrast, the number of species involved remained almost constant. The biomass and the grain yield of the crops on the treated areas did not exceed that on the controls until towards the end of the experiment. In contrast to the majority of relatively rapidly decomposing herbicides (phenoxy-acetic acid derivatives) which remained effective only in the year of application, the application of a persistent herbicide (simazine) produced more enduring effects on several omponents of the ecosystem. These effects were still evident during the following year and reduced the yield of the crop. The multivariate statistical tests used to interpret the primary data proved suitable for obtaining quantitative measures of change in the structure of the plant community and other parameters characterizing the ecosystem, even at an early stage. The use of these methods in investigations at ecosystem level (e.g., in questions relating to bioindicators) are promising.

Zum Ionenaustausch einwertiger Kationen an synthetischen Natriumpolysilicaten mit Schichtstruktur

Abstract: Die Kationenaustauschgleichgewichte der synthetischen Natriumpolysilicate Ilerit (Na2O · 8,3 SiO2 · 8,9 H2O) und Magadiit (Na2O · 13 SiO2 · 6,8 H2O) mit H+, Li+- und K+-Ionen wurden im Hinblick auf ihre Selektivitatsverhalten untersucht Es resultiert folgende Ionenselektivitatsabstufung: H+ > Na+ > Li+ > K+ Die thermodynamischen Grosen ΔG, ΔH und ΔS wurden uber die integrale thermodynamische Gleichgewichtskonstante Kth der Ionenaustauschreaktionen bestimmt Ion Exchange of Monovalent Cations in Synthetic Sodium Polysilicates with Layer Structure Cation-exchange equilibria of synthetic sodium polysilicates Ilerit (Na2O · 83SiO2 89 H2O) and Magadiite (Na2O · 13 SiO2 · 68 H2O) with H+, Li+ and K+ Ions were investigated with respect to their selectivity behaviour The range of ion selectivity is: H+ > Na+ > Li+ > K+ Thermodynamic data ΔG, ΔH, and ΔS were determined by means of the integral thermodynamic equilibria constants Kth of the ion-exchange reactions

Phasenumwandlungen von kristallin‐flüssigen Modifikationen durch photochemische Isomerisierung

Abstract: Phase Transitions of Liquid Crystalline Modifications by Photochemical Isomerisation On irradiating of liquid crystalline phases of aromatic azo- and azoxy-compounds, stilbenes or of derivatives of cinnamic acid by light of appropriate wave lengths the liquid crystalline phase will be converted into the isotropic liquid. In case of the azo- and azoxy-compounds studied this process is reversible, in case of the stilbene and cinnamic acid derivatives partially irreversible. The experimental results indicate that the photoinduced phase transition is caused by a trans-cis-isomerisation. For azo-compounds with more liquid crystalline phases also photoinduced transitions are possible between different liquid crystalline phases.

Synthese und Reaktionen carbocyclischer Acyl‐keten‐S,S‐acetale

Abstract: Synthesis and Reactions of Carbocyclic Acyl-ketene-S,S-acetales Cyclohexanone, tetralone(1) and indanone(1) react with CS2 in the presence of bases and after methylation to 2-[bis(methylthio)-methyliden]-cyclohexanones 1,4-tetralones(1) 2,5 and -indanones(1) 3,6. In some cases thiophenes 8 and 9 are formed. The dimethyl-S,S-acetales 1, 2a and 3a react with mono or dinucleophiles to S,N- or N,N-acetales, with hydrazines to indazolone 22 or the pyrazole 23. Oxidation with H2O2 yield disulfones 25 and 27. The structure of products are determined by ir- and 1H-n.m.r.-spectroscopy.

Structure and function of the conidiospore pigments of Penicillium cyclopium

Abstract: The cell wall of mature, green condiospores of Penicillium cyclopium Westling contains at least two pigments: A green chromoprotein which is extractable by means of formic acid or liquified phenol and a black insoluble pigment. Both fractions after long term treatment with boiling conc. HCl leave black amorphous residues which, due to their chemical and physico-chemical properties, belong to the group of melanins. The chemical structure of these melanins is still unidentified. No degradation products typical for indol-type or catechol-type melanins have so far been detected. During spore maturation parallel to an increase of pigmentation (determined by remission), the melanin residue left after acid hydrolysis of spores increases. The mature, dark green spores of the wild type strain contain about 40% melanin, the yellow-green spores of the mutant aux-glu 1 about 36%. The unpigmented spores of mutant res-eth 1 possess a melanin content of only about 5%. This value is nearly the same as that found in hyphae, which in all strains are yellowish-brown. The heavily pigmented condia of the wild type strain are about 100-times less sensitive to UV-radiation compared with the unpigmented spores of the mutant res-eth 1. The reduced sensitivity indicates that, as with other microorganisms, the conidia pigments of P. cyclopium are protective components of the spores.

Synthese und mesomorphe Eigenschaften von 4-[trans-4-n- Alkylcyclohexanoyloxy]-benzoesäurephenyl- und 4-Benzoyloxybenzoesäure-cyclohexylestern

Abstract: Synthesis and Mesomorphic Properties of Phenyl 4-[trans-4-n-alkyl-cyclohexanoyloxy]-benzoates and Cyclohexyl-4-benzoyloxybenzoates Synthesis and liquid-crystalline properties of terminal and lateral substituted phenyl 4-[trans-4-n-alkylcyclohexanoyl-oxy]-benzoates 1–13, cyclohexyl 4-benzoyloxybenzoates 14–17 and phenyl 4-benzoyloxybenzoates 18–23 are described. The effects of alicyclic part and of lateral substituents are discussed.

Kristallin‐flüssige Bis‐[trans‐4‐n‐Alkylcyclohexancarbonsäure]‐hydrochinonester

Abstract: Liquid Crystalline Hydroquinone Bis-[trans-4-n-Alkylcyclohexane]-carboxylates The synthesis of methyl-, ethyl-, chloro-, bromo-, cyano- and methoxy-substituted esters of hydroquinone 1–7 and their mesomorphic properties are described The title substances exhibit a large range of mesophases and clearing points about 40–50°C higher than that of the analogous esters of benzoi cacids 4-Benzoyloxyphenyl trans-4-n-alkylcyclohexanecarboxylates 8–11 show nematic properties

Enzymes of plastid ribosome-deficient mutants chloroplast ATPase (CF1)

Abstract: The mutant line “albostrians” ofHordeum vulgare L. was investigated by a variety of methods to detect the presence of the chloroplast coupling factor of photophosphorylation (CF1). The plastids in white leaves of the line “albostrians” lack ribosomes and are therefore not able to synthesize proteins. Plastid membranes were isolated from light-grown and dark-grown leaves of the wild-type and of the plastid ribosome-deficient mutant. CF1 could be removed from chloroplast membranes of the wild-type by treatment with EDTA. However, no ATPase activity was found in EDTA extracts of the mutant, and no trace of CF1 could be detected in this extract by reaction with antiserum against CF1 in two-dimensional immunoelectrophoresis. Eight isoenzymes of ATPase were found in the fraction of soluble proteins of green wild-type leaves. No CF1 is detected in this fraction isolated from mutant leaves, but four of the ATPases (not identical with CF1) are reduced in activity or lacking. Visualization of CF1 upon internal membranes of etioplasts of the wild-type was made possible by a special electron microscope procedure. CF1 particles were found in large numbers attached to the pro-thylakoid membranes. CF1 particles could not be observed upon the membranes from plastids prepared from the mutant. Since no trace of CF1 could be detected in the plastids of the mutant by various methods, it is concluded that the absence of CF1 in this mutant is a direct effect of the deficiency in the capacity of the plastid to synthesize proteins.