Refine
Year of publication
- 1974 (19) (remove)
Document Type
- Article (19) (remove)
Language
- English (19) (remove)
Has Fulltext
- yes (19)
Is part of the Bibliography
- no (19)
Keywords
Institute
- Physik (8)
- Biochemie und Chemie (2)
- Biowissenschaften (2)
- Gesellschaftswissenschaften (1)
An improved method for isolation of yeast m utants auxotrophic for 5′-dTM P is presented. The procedure employs the two folic acid antagonists am inopterin and sulfanilam ide (SAA). Selectiveness of the procedure depends on concentration of SAA and time of incubation.
44 mutants auxotrophic and 3 conditionally auxotrophic for 5′-dTMP were isolated. All belong to one complementation group. The corresponding gene was designated TMP1. Tetrad dissection revealed its chromosomal nature. TMP1 is not closely linked to the genes ADE2,, LEU1, ARG 4, ILV2, HIS5, LYS1 and the mating type locus. With the centromere-linked genes ARG4 and LEU1 I gene TMP1 exhibited second division segregation frequencies of 0.42 and 0.53 respectively, indicative of centromere-linkage.
Strains auxotrophic and conditionally auxotrophic for 5′-dTM P were all respiratory deficient (petite). Genetical analysis indicates that the petite phenotype is due to loss of the rho factor in cells harbouring either tmp1 or tmp1ts alleles.
Resting potato tuber tissue possesses only faint activity of the two dehydrogenases of the oxidative pentose phosphate cycle, glucose-6-phosphate- and 6-phosphogluconate dehydrogenase. Slicing of the tissue, however, greatly enhances the action of both enzymes. The slicing-induced increase in activity is a consequence of intensified action of at least 5 glucose-6-phosphate dehydrogenase isozymes and a more differentiated activation/inactivation of seven 6-phosphogluconate dehydrogenase isozymes.
Using density labelling and isopycnic equilibrium centrifugation it could be demonstrated, that the bulk of both enzymes appearing after slicing the tissue is the result of de novo synthesis rather than activation of pre-existing proenzymes.
Within the framework of the pairing plus quadrupole interaction model and by using the technique of quasi spin formalism it is possible to determine the collective potential and kinetic energy surfaces as analytic functions of the particle number in the limit that single particle splittings are neglected. Pushing the quasi spin model in an extended version up to the 4th order in perturbation theory the stiffness and mass parameters of harmonic and anharmonic terms for Dy, Er, Yb, and Hf-isotopes have been calculated. The theoretical particle dependence of collective quantities shows a good qualitative and even quantitative agreement with experimental data and former calculations.
The extension of the nuclear two-centre-oscillator to three and four centres is investigated. Some special symmetry-properties are required. In two cases an analytical solution of the Schrödinger equation is possible. A numerical procedure is developed which enables the diagonalization of the Hamiltonian in a non-orthogonal basis without applying Schmidt's method of orthonormalization. This is important for calculations of arbitrary two-dimensional arrangements of the centres.
The cooperative problem for a lattice gas on a plane, square lattice and on a simple cubic lattice is solved by a system of two coupled, transcendental equations, derived by a combinatorial method, which describes a homogeneous or periodical particle density on the lattice as a function of the temperature and the chemical potential of the lattice-gas.
For the particle interaction a Hard-Core potential (nearest neighbour exclusion) with a soft long-range tail is assumed. The zero-component of the Fourier-transform of this long-range interaction part can be positive or negative.
The system of transcendental equations is solved by a graphic method. As a result, the complete pressure-density state diagram and the pressure-temperature phase diagram can be drawn.
The lattice-gas exists in three stable phases: gas, liquid and solid. Three phase changes are possible: condensation, crystallization and sublimation.
Critical points of condensation and freezing are examined. The number of possible phases and phase changes at a fixed temperature depends on the geometric structure of the particle interaction.
A careful investigation of different corrections to binding energies of electrons in almost critical fields is performed. We investigate quantitatively the influence of the nuclear charge parameters, nuclear mass, degree of ionization on the value of the critical charge of the nucleus. Rather qualitative arguments are given to establish the contribution of the quantumelectrodynamic corrections, which are found to be small. Some phenomenological modifications of QED are quantitatively investigated and found to be of negligible influence on the value of the critical field. For heavy ion collisions with Z1+Z2>Zcr the critical separations between ions are given as results of precise solutions of the relativistic two coulomb center problem. Corrections due to electron-electron interaction are considered. We find (with present theoretical accuracy) Zcr=173±2, in the heavy ion collisions Rcr(U-U) = 34.7±2 fm and Rcr (U-Cf)=47.7±2 fm. We shortly consider the possibility of spontaneous muon production in muonic supercritical fields.
Introducing correlated continuum wave functions for the two- and re-particle-continuum a microscopic theory of nuclear reactions based on a method of Fano is developed. The S-matrix-elements are given by the matrix-elements between correlated continuum wave functions and bound state wave functions. The antisymmetrization of the continuum wave functions with more than one particle in the continuum is included. The theory can be straightforwardly applied on the n-nucleon-emission process following photo- and particle excitations.
Theses against occultism
(1974)
Over 6260 fungi have been isolated from samples of feathers, nests, pellets, droppings, cloaca contents and visceral organs of 92 species of free-living birds in Czechoslovakia and Yugoslavia. Several species have been obtained of fungi pathogenic to homeotherms, poikilotherms and plants, and many fungi recorded belong to the toxinogenic species.Cellulolytic fungi have participated with 44.3 % in the total number of fungi, and keratinolytic fungi with 18.3 %. The thesis has been confirmed that habits (specific bionomics) of the birds influence,. to a certain degree, the distribution of the fungi among them. According to the results of this study, the fungi may conveniently be divided into three categories with respect to the character of their distribution and dispersal by free-living birds: (1) euryornithochous fungi , the occurrence of which in birds is undetermined by the birds' habits (ubiqitous species: Aspergillus flavus, Gliocladium roseum, Rhizopus. nigricans, Trichothecium roseum); (2) mesoornitohochorous fungi, the occurrence of which in birds is determined to a certain degree by the birds' habits (e. g., Aphanoascus fulvescens, Arthrodermcr curreyi, Chrysosporium keratinophilum, C. tropicum, Mucor hiemalis); (3) stenoornithochoruss fungi, which are associated with certain habit groups of the birds only (e. g., Aphanoascus terreus, Arthroderma ciferrii, A. tuberculatum,.Aspergillus fumigatus, Chrysosporium pannorum, Ctenomyces serratus). The importance of free-living birds in the spreading of pathogenic organisms has also been discussed from a more general point of view, particularly with regard to several epidemiologically important aspects of bird ecology such as synanthropism, migration (making possible a long-range carriage of pathogens or infected vectors), colonial breeding or mass roosting.