Volume 25, Issue 10

Synthetic Haidingerite, dicalcium arsenate monohydrate was studied by infra-red techniques from 4000-400 cm -1 . All the observed bands have been assigned and the data are discussed in the light of known crystallographic structure.

Triphenylphosphin und Chloridionen bilden mit den Nitridchloriden des Molybdäns und Wolframs, MNCI 3 (M = Mo, W) definierte Komplexe des Typs MNCl 3 · P (C 6 H 5 ) 3 sowie [MNCl 5 ] 2⊖ , in denen Metall-Stickstoffmehrfachbindungen vorliegen. Die Verbindungen werden schwingungsspektroskopisch charakterisiert.

Bis (dimethylamino) -boronhalides react with dibenzonitrile palladium-dichloride (C 6 H 5 CN) 2 PdCl 2 in a different manner. Bis (dimethylamino) -boronchloride forms, just like bis (dimethylamino) methylborane complexes of the type Cl 2 Pd [ (CH 3 ) 2 N] 2 BX (X = Cl, CH 3 ). On the contrary the analogous bromo- and iodoboranes react with coordinated benzonitrile and form the diborylamine palladium complexes C 6 -C(X 2 ) -N{B[N(CH 3 ) 2 ] 2 } 2 PdX (X = Br, J) which probably are dimeric. The B -N-groups presumably act as π-ligands.

The infrared spectra of polycrystalline pyridinium hexahalo titanates (III), (C 5 H 6 N) 3 [TiX 6 ] (X = Cl, Br), show a slight deviation of the complex ions from the form of a regular octahedron, as previously found for K 2 Na [TiF 6 ]. The spectra can be interpreted by assuming D 4h symmetry. The difference between the axial and the equatorial TiX bond lengths is estimated by calculation of the force constants; it is in the order of about 0,01 A.

Titanium (IV) complexes of monofunctional bidentate Schiff bases, such as salicylideneaniline, β-hydroxynaphthylideneaniline, benzylidene-o-aminophenol, benzylidene-2-hydroxyethylamine and benzylidene-2-hydroxy-n-propylamine have been prepared. The reactions between titanium isopropoxide and the Schiff bases in varying molar ratios resulted in the synthesis of several new derivatives of the general type, Ti (OPr i ) 4-x (SB) x (where x = 1. 2. 3 or 4 and SB ⊖ is the anion of the Schiff base SBH) in quantitative yields. The molecular weight determinations of some of the soluble derivatives indicate the possibility of coordination numbers five or seven for the central metal atom.

Das aus Tetracyclon mit Lithium entstehende Metallketyl assoziiert in höherer Konzentration zu zwei ineinander umwandelbaren Dimeren-Komplexen (c und d), für die wegen der hohen Spindichte am Sauerstoff eine intermolekulare Elektronen-Spin/Spin-Kopplung zur Elektronenkonfiguration Triplett EPR-spektroskopisch nachweisbar ist. Der Zusammenhang zwischen Tetracyclon, Tetracyclon-Monoanion, den Dimeren-Komplexen und dem Tetracyclon-Dianion und der Einfluß von Phenyl- und Brom-Substitution wird diskutiert.

Es werden die Darstellung und die Eigenschaften von β-Alkoxypropionsäure-Cholesterinestern beschrieben und mit denen der entsprechenden Fettsäuren verglichen. Die Schmelzpunkte nehmen mit einer steigenden Zahl von Ätherfunktionen ab. Alle untersuchten Verbindungen durchlaufen die cholesterinische Phase nur beim Abkühlen. Smektische Phasen wurden nicht beobachtet.

Durch Umsatz der Natriumsalze von 2-Trifluormethyl-benzimidazolen und Tribromimidazol mit Chlorameisensäureestern werden die entsprechenden N-Carbonsäure-Derivate erhalten. Diese stellen eine neuartige Gruppe insektizider und acarizider Wirkstoffe dar, deren Wirkungsweise wahrscheinlich durch Entkopplung der oxydativen Phosphorylierung verursacht wird.

14 C -CH 3 O-Trichlorphon wurde i. v. und i. p. an Ratten appliziert und 14 C in Organen und Leberproteinen bestimmt. Die Hauptmenge wurde in Leber als nicht extrahierbarer 14 C gefunden. Die spezifische Aktivität des 14 C bleibt in den mit Ammonsulfat gefällten Globulinen und Albuminen der Leber auch nach mehrfacher Umfällung konstant, so daß 14 C als chemisch fest am Protein gebunden anzusehen ist. Wahrscheinlich finden Alkylierungsreaktionen nicht nur an niedermolekularen Peptiden, z. B. Glutathion, sondern auch an Proteinen statt. Die Konsequenzen dieser Untersuchungen werden diskutiert.

Volume, dry weight, and composition of etioplasts, of greening etioplasts and of chloroplasts were determined. During greening there was a threefold increase in volume, whereas the dry weight only doubled. Thus the relative water content was lower in etioplasts than in chloroplasts. There was no difference in the amount of plastid stroma between etioplasts and chloroplasts, but the content of water-insoluble substances increased from 3.9·10 -12 g to 12.3·10 -12 g during plastid development. The insoluble proteins increased from 1.5·10 -12 g in etioplasts to 6.6·10 -12 g in chloroplasts. After an initial decrease from 2.4·10 -12 g to 1.8·10 -12 g the total lipid content reached 5.7·10 -12 g in chloroplasts. There were only quantitative changes in lipid composition during plastid development. Both chloroplasts and etioplasts contained the major colourless lipids: monogalactosyl-diglyceride, digalactosyl-diglyceride, phosphatides, and the sulfoquinovosyl-diglyceride. Furthermore, it was observed that the spectrad composition of the light in which the plants were grown had great influence on the dry weight of the chloroplasts, though the percent composition, except chlorophyll b, was not affected.

Injection of α-amanitin inhibits both the synthesis of ribosomal and DNA-like RNA as measured by the incorporation of radioactively labelled orotic acid and ortho-phosphate into RNA extracted by phenol and subsequently fractionated by density gradient centrifugation and MAK column chromatography.

Mycel-extracts of P. chrysogenum catalyse the formation of 5- (2-aminoadipoyl) -cysteinyl-valin out of its aminoacid components. For the synthetical preparation of this compound the solid-phase method is particularly suited. The synthesis can be carried out even with very small quantities of substance and thereby allows the preparation of radioactive labelled L-5- (2-aminoadipoyl) -L-cysteinyl-L-valin of relatively high specific activity.

Die Kenntnis der chemischen Potentiale der Salze im Zytoplasma gibt Aufschluß darüber, ob die Wechselwirkungen zwischen den Komponenten des Zytoplasmas mit dem Modell einer kompliziert zusammengesetzten, konzentrierten makromolekularen Lösung zu beschreiben sind oder ob im Zytoplasma ein hydratisiertes makromolekulares Netzwerk vorliegt, in dem die Salzionen durch starke Wechselwirkungen zum Teil immobilisiert werden, wie in der Sorptionstheorie von Troshin oder der Association-Induction-Hypothese von Ling angenommen wird. Als Modell für das Zytoplasma dienten konzentrierte Zytoplasma-Fraktionen aus Kalbsleber, deren Salze vollständig durch KCl in physiologischer lonenstärke ersetzt wurden. Als Maß für das chemische Potential wurde neben den lonenkonzentrationen der mittlere Aktivitätskoeffizient von KCl über EMK-Messungen an einer Dreikompartment-Meßzelle mit einer Kationen- und einer Anionenaustauscher-Membranelektrode bestimmt. Die Ergebnisse zeigen, daß der mittlere Aktivitätskoeffizient von KCl in den Zytoplasma-Fraktionen mit steigender Makromolekülkonzentration abnimmt, aber nur geringfügig gegenüber dem Wert in reinen KCl-Lösungen gleicher Konzentration erniedrigt wird. Das gilt auch dann, wenn man bei der Berechnung der Ionenkonzentrationen etwa 0,4 g gebundenes Wasser pro g Makromolekül-Trockengewicht als non-solvent-Wasser berücksichtigt. Bei einer Bindung oder Immobilisierung der Salzionen in dem makromolekularen System wäre dagegen eine starke Erniedrigung der mittleren Aktivitätskoeffizienten zu erwarten.

Quantitative singlet absorption spectra dependent on solvent, temperature, and concentration are shown. The bands observed in the visible and UV region are assigned to 3 π → π*-electron transfers. Measurements at different acidities showed that the pheophytin molecule can be present in 3 prototropic forms; as a base, a mono- or a divalent cation. In polar solvents of concentrations >10 -4 M dimerization occurred. Larger clusters were formed in non-polar solvents at concentrations <10 -4 Μ and at temperatures below ca. 200 °K. The quantitative triplet (T) -absorption spectra for pheophytin a and b are also reported: the longest wavelength T-T-band is expected in the region 5000-8000 cm -1 . The relaxation times and quantum yields of triplet formation are given; simple first order kinetics were found to fit the decay curves.

Es werden hier die Kubelka-Munk- Gleichungen, die von vielen Autoren zur Berechnung der Lichtverteilung in streuenden und absorbierenden Medien benutzt werden, aus allgemeinen Transportgleichungen hergeleitet. Dabei wird gezeigt: 1. unter welchen Bedingungen die Kubelka-Munk -Gleichungen gültig sind, und 2. welche Bedeutung die in diesen Gleichungen enthaltenen Parameter „Absorption“ und „Streuung“ haben. Insbesondere wird der Zusammenhang zwischen den optischen Eigenschaften der Gesamtheit vieler kleiner Teilchen und der Absorption und Streuung des einzelnen Teilchens diskutiert. Über diesen Zusammenhang, der für die „in vivo“-Spektroskopie sehr bedeutsam ist, herrscht vielfach Unklarheit.

Efflux of ions across the plasmalemma of root cells was studied in order to understand how the plasmalemma acts as a barrier to passive ion distribution. High external concentrations of salts (KCl, CaSO 4 etc.) were found to increase the permeability of the plasmalemma to Cl ⊖ . The decrease in resistance of the plasmalemma to anion permeation was suggested to be due to binding of cations to negatively charged groups of the membrane. We have stressed the significance of binding of cations (Ca 2⨁ , H ⨁ , K ⨁ , Na ⨁ ) to phospholipid films 10 for the mechanism of ion permeation across the plasmalemma of plant cells 1-4 . H ○ -efflux from salt-loaded roots is likely to be stimulated with increasing external salt concentration. Efflux of Cl ⊖ was stimulated by externally applied H 2 SO 4 . The different effect of Ca 2⨁ -salts on Cl ⊖ - and Rb® (K®)-permeability of salt-loaded roots suggests that it is not only he H ⨁ -ions which decrease the charge density of the membrane but also the Ca 2O -ions (and monovalent cations at sufficient concentrations?). Thus Ca 2⨁ increases passive anion permeability by decreasing the density of negative charges of the membrane and decreases passive (nonspecific) monovalent cation permeability. Ca 2⨁ and H ⨁ (K ⨁ , Na ⨁ ) appear to act synergistically on Cl ⊖ -permeability and antagonistically on monovalent cation permeability. The high Rb® (K®)-efflux across the plasmalemma (fig. 1) may contribute to the electric conductance and potential of the plasmalemma. The plasmalemma is to be expected to depolarize as the pH of the medium is lowered. However, this would not unequivocally point to H ⨁ -conductance as a major component f plasmalemma conductance (KITASATO 16 ), since permeability of the plasmalemma to Cl ⊖ (PCl) appears o be increased as the pH is lowered. It is concluded that the plasmalemma of plant cells acts as an electrostatic barrier against anion diffusion. The lipid of the membrane favours the permeability to apoiar molecules as suggested by OVERTON 5 and COLLANDER 6 . The general barrier action to the movement of polaf and charged molecules is believed to arise from a compact arrangement of cholesterol and apoiar hydrocarbon chains of phospholipids (and apoiar amino acid residues). Small polar molecules penetrate the lipid lattice easier than big polar molecules. However, the charged groups of the phospholipids play an important role in permeability to ions rather than the plasmalemma being an electrically neutral lipid filter.

Autoradiographic investigations on the structure of the perithrophic membranes of Calliphora erythrocephala Mg. showed regular alternating stripes having different affinities for anions and cations. This structure may have the qualities of the theoretically discussed mosaic membran.

A halogenated benzoquinone has been found to inhibit the photosynthetic electron transport system in isolated chloroplasts. 2·10 -6 ᴍ of dibromo-thymoquinone inhibit the Hill- reaction with NADP, methylviologen or anthraquinone to 100%, but do not effect the photoreduction of NADP at the expense of an artificial electron donor. The Hill - reaction with ferricyanide is inhibited even at the high concentration of 2·10 -5 ᴍ of dibromo-thymoquinone to only 60%. The remaining reduction in the presence of the inhibitor reflects the rate of ferricyanide reduction by photosystem II. It is concluded that the inhibition of electron transport by the quinone occurs between photosystem I and II and close to or at the functional site of plastoquinone.

Neonatally thymectomized mice show a markedly reduced mesothelial proliferation following an antigenic stimulus. As thymectomy causes a drastic reduction of circulating lymphocytes, lymphopenia may be the cause of the reduced mitotic rate of mesothelial cells. In order to prove this hypothesis, lymphopenia was caused by a) drainage of the thoracic duct and b) by injection of anti-thymocyte serum. In both types of experiments a drastic reduction of mesothelial proliferation was observed showing good correlation with the degree of lymphopenia. These results indicate that lymphocytes of thymic origin release mitosis promoting factors and thereby contribute to an immune response.

Treatment of chick embryo fibroblast cells or mouse L-cells with homologous interferon resulted in a reduced formation of poxvirus specific polysomes and of viral RNA. In chick cells infected with cowpox virus the reduced formation of viral polysomes and virus-specific RNA after pretreatment of cells with interferon was observed at all timepoints studied (1 - 6 hours p. i.). Exposure of cells to poly I: poly C caused a similar effect. In mouse L-cells infected with vaccinia WR virus pretreatment with interferon did not result in a reduced formation of viral polysomes or virus-specific RNA up to 1 hour p. i. At about 45 min even a slight increase of the formation of viral polysomes and RNA was observed. At later stages of infection (2 -4 hours p. i.) a reduced synthesis of viral polysomes and RNA was seen, similar to that found in the chicken fibroblast system.

Salad, soybeans, rye and tobacco plants, grown on field in the open air or in greenhouses contain benzo (e) pyrene, benzo (a) pyrene, perylene, anthanthrene, benzo (ghi) perylene, dibenzo (a,h) anthracene, and coronene through air pollution. Plants of the same seeds, grown in a special room with air supply by filter-combination (cellulose filter + filtering charcoal + special filters) and with air lock for personnel (changed clothes) show non of the polycyclic hydrocarbons. Under these conditions, it is not possible to find any hints at biosynthesis of the above mentioned polycyclic hydrocarbons.

Pre-reatment of rats with various doses of cytostatics and antimetabolites (cyclophosphamide, mitomycin-C, 6-mercaptopurine, 6-azauridine and 5-azaorotic acid) permits successful heterotransplantation of Ehrlich ascites tumor, as indicated by the progressive growth of the tumor cell population. Experiments with cyclophosphamide suggest a direct dose dependence of the rate of tumor growth in heterologous recipients.