RECOVERY OF HAEMOPHILUS INFLUENZAE FROM ULTRAVIOLET AND X-RAY DAMAGE

Abstract— Results of experiments on reactivation of ultraviolet (u.v.)-irradiated Haemophilus influenzae and cellular reactivation of u.v.-damaged transforming deoxyribonucleic acid (DNA) and bacteriophage are reported. Liquid-holding recovery (LHR) is small for the u.v.-sensitive mutant BC100 which, relative to the wild type, also has greatly reduced host-cell reactivation (HCR) of u.v.-inactivated phage, and competent cultures show reduced competent cell reactivation (CCR) of u.v.-inactivated transforming DNA. BC100 cells can be transformed with DNA isolated from the wild type strain Rd to a u.v. resistance similar to that of Rd, and irradiation of the DNA reduces the transformation frequency for this marker (uvr). The u.v.-resistant mutant BC200 displays very little LHR under the usual conditions where reactivation occurs after plating. The colony-forming ability (cfa) of irradiated BC200 is greater than that of Rd, but HCR and CCR are the same on this mutant as on the wild type. The major difference between Rd and BC200 is the enhanced u.v. survival of cfa of the latter. It was determined that this difference reflects cell lysis of irradiated Rd and lack of lysis in BC200 cultures. That lysis is closely correlated with damage to the bacterial chromosome is suggested by the finding that the lytic response of Rd (as determined turbidimetrically) can be negated by the liquid-holding procedure, but lysis of BC100 (which lacks comparable DNA-repair ability) can be only partially inhibited by this procedure. LHR occurs when post-plating dark recovery is incomplete, is temperature-sensitive, and occurs unimpeded when post-u.v. protein synthesis is inhibited by chloramphenicol. It is suggested that enzymatically catalyzed reactivation of DNA occurs or is initiated during liquid-holding of u.v.-irradiated H. influenzae Rd and that the necessary enzyme(s) exists prior to appearance of u.v. lesions in the DNA. Results are reported for X-ray inactivation of transforming DNA as assayed on BC100, Rd and BC200 and of the cfa of the three strains.     

Zur Bestimmung von β-Aminocrotonsäureester nach Migration in Lebensmittel

β-Aminocrotonic esters are of great importance as stabilizers for the production of clearly transparent food packaging of PVC. For the purpose of studying the migration into foods a thin-layer Chromatographic and a polarographic method were elaborated. The TLC method consists of the visual comparison of the intensity of the spots after treatment with Fast Blue B salt. The polarographic determination is carried out after nitrosation of the stabilizer. By the TLC method 10^?7 g of ester per spot are still detectable; the concentration which is still determinable by cathode-ray polarography is 5×10^?7 g of ester and by conventional d.c. polarography 5×10^?6g of ester per ml of final solution. After extraction with acetonitrile traces of the stabilizer which are migrated into edible oil are still determinable down to 2 ppm by the methods described.     

The determination of molybdenum and tungsten in sea and surface water

A simple method for the determination of molybdenum and tungsten in sea and surface water is presented. Molybdenum and tungsten are concentrated on activated charcoal by adsorption as the ammonium pyrrolidine dithiocarbamate complex; the optimal pH for adsorption is 1.3. Mo and W are then determined by thermal neutron activation, forming ⁹⁹Mo (T_{$\text{1}\text{2}$} = 66.7 h) and ¹³⁷W (T_{$\text{1}\text{2}$} = 23.8 h), respectively. The ^99mTc daughter of ⁹⁹Mo is measured as soon as the equilibrium between ^99mTc(T_{$\text{1}\text{2}$}= 6 h) and ⁹⁹Mo is established. The detection limits are 0.05 μg Mo l^-1 and 0.05 μg W l^-1 (or 0.001 μg W l^-1 after a simple chemical separation).     

A hydrodynamic voltammetric study of the ferricyanide/ferrocyanide system with convective electrodes of platinum,gold, glassy carbon,carbon film,and boron carbide

Hydrodynamic voltammetry employing empirically determined mass transport coefficients is used to determine heterogeneous rate constants and transport coefficients for the ferricyanide/ferrocyanide system in 0.1 M phosphate buffer and other supporting electrolytes with turbulent tubular and rotated disk electrodes of platinum, gold, glassy carbon, carbon film, and boron carbide. Different kinetic parameters are obtained at the various electrode materials. For the platinum, gold, and boron carbide electrodes, the magnitudes of the rate parameters depend on scan direction. The nature of this hysteresis varies with the electrode material and is explained in terms of adsorbed oxide and ionic layers or other phenomena not described by simple double layer theory.     

MO-LCAO-Calculations on polymethines. V. PPP-type calculations and configuration analyses of simple prototype dyes in terms of molecular subsystems

In order to elucidate certain controversies in interpreting the π-electronic structure of some simple quinone and indigo dyes the Pariser–Parr–Pople SC _β,γ-wave-functions have been subjected to configuration analyses. Whereas 2,5-diamino-quinone (1) can be excellently represented by coupling of two trimethine-merocyanine chains, the analogous consideration is less appropriate with bispyrrolindigo (2). In this case the results of the configuration analyses indicate clearly the limited applicability of the Longuet/Higgins–Murrell–method.     

Alkylation d'anions ambidents en catalyse par transfert de phase. Cas des hydroxypyridines

Alkylation of ambident-anions derived from 2- and 4-pyridones yield by phase transfer catalysis, 80% of N-substitution and 20% of O-substitution. Change of salts, solvents, temperature and alkyl halide do not interfere very much with the N- and O-alkylation percentage of substitution. Overall yields range from 40 to 80% with primary or secondary alkyl halides.     

Extra-atomic relaxation energies for the 3d-transition metal series obtained with SCF hole-state calculations

A method to calculate extra-atomic relaxation energies is presented. It is based on the use of SCF hole-state calculations. The E_R^ea (2s) and E_R^ea (2p) values obtained for the 3d-transition metal series are in fair agreement with experimental values.     

Energy dependence of SF6 dissociation by pulsed CO2 laser radiation

The fractional dissociation,³²Γ, of ³²SF₆ by the output of a pulsed TEA CO₂ laser has been found to depend upon Φ, the total integrated laser intensity, as ³²Γ ∞ Φ^m for both the P(20) and P(16) laser lines, where m ≈ 3 in the range 2 < Φ < 7.2 J/cm² and increases from 3 to ≈ 4 as Φ is reduced from 2 to 0.9 J/cm².