Showing papers by "University of Basel published in 1972"

Photoelectron Spectra of Azabenzenes and Azanaphthalenes: I. Pyridine, diazines, s‐triazine and s‐tetrazine

Abstract: The experimental and theoretical basis of a recently proposed reassignment of the bands in the PE. spectra of pyridine, pyridazine, pyrimidine and pyrazine is discussed in detail. A characteristic feature of the derived orbital sequence is that it takes the ‘through-space’ and ‘through-bond’ interaction between the ‘lone pair’ basis orbitals explicitly into account. A simple parametrization of the orbital energies, based on HMO-type models for the π-orbitals and for the ‘lone pair’ linear combinations, yields excellent agreement with the observed band positions in the PE. spectra of s-triazine and s-tetrazine. Our new assignment is compared to those proposed previously.

The π-Orbital Energies of the Acenes

Abstract: The ‘observed’ π-orbital energies ϵv,j = −Iv,j derived from the vertical ionization potentials obtained by a photoelectron spectroscopic investigation of the acenes benzene A(1), naphthalene A(2), anthracene A(3), naphthacene A(4) and pentacene A(5) have been compared with π-orbital energies calculated by three different approximations: (a) the standard Huckel HMO model; (b) a first-order perturbation treatment, based on (a), that takes into account bond length changes which follow the ionization process; (c) a SCF π-electron model of the type proposed by Pople and by Pariser & Parr. In agreement with previous experience it is found that model (b) yields the most satisfactory parametrization of the experimental data.

Robertsonian chromosomal variation and identification of metacentric chromosomes in feral mice.

Abstract: Cytogenetic studies of feral mice (M. musculus) from various but predominantly Alpine areas of Switzerland, carried out on random samples collected by spot-checks, established the widespread existence of metacentric chromosomes in the somatic karyotype. Despite the finding of the common occurrence of some of the metacentrics in different places, the examination of the possible homology or heterology by breeding procedures revealed the surprising fact that independence, partial or heterobrachial homology of the metacentric chromosomes prevail among mice from different geographical areas. Thus, the general picture is that of an array of different metacentric chromosomes derived from independent events of Robertsonian variation in the process of evolution. — While heterozygosity with independent metacentrics within a Robertsonian system may have a bearing on the fertility rate of a given mouse population, a more severe impairment of the reproductive capacity must be taken into account in mouse populations which possess different metacentrics with mono- or heterobrachial homologies. These conditions favour the assumption of the existence of a selective system of reproductive barriers further subdividing the species in many, more or less stable, micro-populations. — The chromosomal arms (telocentrics) involved in the formation of the metacentric chromosomes could be identified by Q- and G-banding techniques in combination with the results of crossbreeding, and were assigned to the corresponding telocentric autosomes of the mouse (Comm. Standard. Genet. Nomenclat. for Mice, 1972). Most of the telocentric autosomes of the mouse are included in one or more of the metacentrics found in the feral populations. By means of their isolation in separate lines, these metacentrics may be useful in experimental biology as marker chromosomes of defined identity carrying known linkage groups.

Photoelectron Spectra of Azabenzenes and Azanaphthalenes: III. The orbital sequence in methyl‐ and trimethylsilyl‐substituted pyridines

Abstract: The ionization potentials of methyl-, t-butyl- and trimethylsilyl-substituted pyridines have been determined by high-resolution photoelectron spectroscopy. The results are discussed in terms of destabilizing inductive and stabilizing conjugative effects of the substituents, and have been parametrized on the basis of a HMO-type perturbation treatment. Our data are in accord with the idea that the topmost occupied orbital in pyridine is a ‘lone pair’ orbital.

The π‐Orbital Sequence in Norbornadiene and Related Hydrocarbons

Abstract: A method outlined previously [1] is used to show that in norbornadiene (3) the b2(π) orbital lies above a1(π), as predicted by theory. This indicates that in 3 through-space interaction between the two basis π-orbitals πa and πb is more important than through-bond interaction. Analysis of the PE.-spectra of 8-isopropylidene-tricyclo[3.2.1.02,4]-octane (13) and the corresponding octene (15) confirms that the π-orbital πc of the exocyclic double bond conjugates more strongly with the symmetric Walsh-orbital es of the cyclopropano moiety than with the π-orbital πa of a double bond in the same position.

Photoelectron Spektra of Azabenzenes and Azanaphthalenes: II. A Reinvestigation of Azanaphthalenes by High-Resolution Photoelectron Spectroscopy†

Abstract: The bands with Iv < 13 eV in the photoelectron spectra of quinoline (IX), isoquinoline (X), cinnoline (XI), quinazoline (XII), and quinoxaline (XIII) have been reassigned in a way consistent with the assignment proposed for pyridine (II), the diazines (III, IV, V), s-triazine (VI), and 1,2,4,5-tetrazine (VII). The bands corresponding to the ejection of an electron from a π-orbital have been identified by a regression calculation based on a HMO perturbation treatment. It has been found that the combined through-space and through-bond interaction of the lone pairs in III, IV, V and in their corresponding benzologues XI, XII, XIII are the same within experimental error ( ±, 0.2 eV). Our assignment is also supported by an empirical correlation of the pKa, 1− values and the mean lone-pair ionization potentials of the azaderivatives I to XIII.

Photoelectron-Spectroscopic Assignment of Symmetry Species to the Lower Electronic States of Unsaturated Hydrocarbon Radical Cations

Abstract: The competitive through-space and through-bond interaction of two symmetry-equivalent, semi-localized orbitals φa, φb, (= π or lone-pair orbitals) in a molecule M of Cs or higher symmetry can lead either to the natural order of the corresponding delocalized orbitals, i.e., ψ− ≈ (φa - φb)/√2 above ψ+ ≈ (φa - φb)/√2 or to the inverted order, i.e., ψ+ above ψ−. It is shown that one can discriminate between these two situations through an analysis of the PE spectrum of a molecule M′ which differs from M only by an additional semi-localized orbital φc of known symmetry behaviour. The method is exemplified by an investigation of the dependence of the n-orbital sequence in 3,6-bridged 1,4-cyclohexadienes on the dihedral angle between the two CCHCHC moieties.

Systematik der jung-präkambrischen PetalonamaePflug 1970

Abstract: In den letzten 7 Jahren sind aus der jung-prakambrischen Nama-Formation von Sudwest-Afrika mehrere hundert Fossilien geborgen worden. Die meisten Stucke liegen in korperlicher Erhaltung vor. Fast alle Funde sind den PetalonamaePflug 1970 zuzurechnen, die ein blattartiges Oberflachenmuster kennzeichnet. Die Formenfulle last folgende Hauptgruppen unterscheiden: Die meisten Funde gehoren zur Hauptgruppe II. Sie werden nach folgenden Merkmalen untergliedert: a) Bauform: «monaxial» oder «bifurcat», b) Wandstruktur: «rangeoid», «pteridinoid» oder «erniettoid») c) Positionen der Ingestions-Offnung: «truncostom», «terminostom», «centrostom» oder «apicostom», d) transversale und longitudinale Gliederung: Korper drei-, zwei- oder einteilig.

Spinal cord tissue cultures--a model for autoradiographic studies on uptake of putative neurotransmitters such as glycine and GABA.

Abstract: Autoradiographische Untersuchungen haben gezeigt, dass3H-Glycin und3H-GABA in kultivierte Neurone und Gliazellen des Ruckenmarks der Ratte aufgenommen werden. Aus unseren licht- und elektronenmikroskopischen Befunden geht hervor, dass die Nervengewebskultur ein geeignetes Versuchsmodell fur Aufnahme und zellulare Lokalisation von Ubertragersubstanzen ist.

Methods of quantitative and qualitative analysis of bird migration with a tracking radar

Abstract: Methods of analyzing bird migration by using tracking radar are discussed. The procedure for assessing the rate of bird passage is described. Three topics are presented concerning the grouping of nocturnal migrants, the velocity of migratory flight, and identification of species by radar echoes. The height and volume of migration under different weather conditions are examined. The methods for studying the directions of migration and the correlation between winds and the height and direction of migrating birds are presented.

Host specificity of DNA produced by Escherichia coli. XVI. Phage lambda DNA carries a single site of affinity for A-specific restriction and modification.

Abstract: Bacteria with A-specific restriction plate unmodified phage λ with an efficiency of 10-2. One mutational event can produce restriction insensitive (sAo) mutants of λ. These differ from the original sA form of λ by no other property than their response to A-host specificity. Two-parental phage crosses involving sA and sAo, respectively, as non-selective marker allowed to map sA between genes cII and O. These data indicate that sA is the only site on λDNA with affinity for A-specific restriction. λDNA is thus an interesting substrate in in vitro A-specific restriction and modification. Using an assay based on the infectivity of λDNA on helper-infected bacteria, A-specific modification activity was found in partially purified sonicates of bacteria with A-host specificity. In parallel to modification, 3H-methyl label from s-adenosylmethionine, the only cofactor required for modification, was transferred to unmodified λDNA. No association of radioactivity was observed in control experiments with DNA from either modified λ·A or from aλsAo mutant. These data suggest that A-specific modification is brought about by DNA methylation and that the sAo mutation not only abolished the affinity for A-specific restriction, but also for A-specific modification.

Correlation of Hückel molecular orbital energies with π-ionization potentials

Abstract: It is shown that simple HMO models which take into account first order bond fixation yield orbital energies forπ-systems which correlate closely with theπ-band positions in the corresponding photoelectron spectra.

Political participation and income level: An exchange

Abstract: Let us first consider voting behavior. Frey's explanation seems to imply one (or more) of several things: (1) that high income individuals are more efficient in the consummation of voting, where the act includes getting to the polling place, deciding upon whom to vote for, etc.; (2) that voting involves activities somewhat akin to those undertaken by high income individuals in the course of their daily business; or (3) that high income occupations involve relatively higher mental effort and lower physical effort than low income occupations.

Humoral transmission of sleep

Abstract: Sleep dialysate obtained from rabbits kept asleep by stimulation of the thalamic sleep area was separated by gel filtration on Sephadex G-10 into two fractions (Pools I and II). The effects of each fraction on the electrical brain activity (EEG) and on the motor behavior were assessed by infusion into the meso-diencephalic ventricular system of rabbit recipients and compared to the hypnogenic activity of the fresh dialysate, and/or its solid residue after lyophilization. Infusion of Pool I induced a marked and highly significant increase of the slow delta activities, symptomatic of ordinary (delta) sleep and a corresponding sleep behavior with decreased motor activity, quantified with an actograph. The hypnogenic activity of Pool I was higher when referred to the total sleep dialysate before fractionation, even though only 5% of the original weight of the solid constituents of the total dialysate was recovered in Pool I. By contrast, infusion of Pool II did neither increase the amount of delta activities nor induce a sleep behavior. Delta curve and actogram were similar to those of control recipients. The hypnogenic highly significant effect of the desalted Pool I (∼30 μg/0.05 ml/25 min) suggests the existence of a specific “sleep factor delta” in this fraction.

Vier neue Metabolite von Giberella zeae: 5-Formyl-zearalenon, 7′-Dehydrozearalenon, 8′-Hydroxy- und 8′-epi-Hydroxy-zearalenon

Abstract: From cultures of Gibberella zeae ergosterol, zearalenone (1) and hitherto unknown minor metabolites, i.e.. 5-formyl-zearalenone (6), 7′-dehydrozearalenone (8), 8′-hydroxyzearalenone (9) and 8′-epi-hydroxyzearalenone (11) were isolated. The production of zearalenone and its congeners proved to be very strongly dependent on the conditions of culture. 5-Formyl-zearalenone (6) as well as 3-formylzearalenone (4) were synthesized from zearalenone (1) and characterized by the di-O-methyl derivatives 7 and 5 respectively. The structure of 7′- dehydrozearalenone (8) was deduced from spectral data. The di-O-methyl derivatives 10 and 12 respectively of the two corresponding epimeric 8′-hydroxy derivatives 9 and 11 yielded the same β-diketone 13. The keto-enol equilibrium of 13 was studied.

Kinetics of cooperative conformational transitions of lineal biopolymers.

Abstract: Cooperative conformational transitions of proteins and nucleic acids are of decisive importance to many processes of molecular biology, and particularly to their regulation. They proceed via numerous interdependent elementary processes, and their kinetics are therefore often complicated. They are frequently also very fast. However, kinetic analyses can be carried out by chemical relaxation methods. The theoretical interpretation is comparatively simple in the case of linear biopolymers. When the linear Ising model extended for kinetics was applied to model peptides and polynucleotides, it provided an insight into the fundamental principles of cooperative transformations.

Thermodynamic and Kinetic Studies on the Cooperative Binding of Proflavine to Linear Polyanions

Abstract: The cooperative binding of proflavine with poly(acrylic acid), poly(α-l-glutamic acid) and polyphosphate has been investigated. In all cases the equilibrium experiments could be described by a recently proposed theory based on a linear Ising lattice of equivalent binding sites. Thermodynamic and spectroscopic parameters are evaluated as a function of ionic strength and discussed in terms of a simplified structural model of dye aggregation on the polyion. Application of the temperature-jump technique generally resulted in a fast initial process which is in most cases followed by a substantially slower further relaxation effect of more or less amplitude. The first process can be quantitatively interpreted in terms of a diffusion controlled reaction mechanism according to the basic model theory. The slow effect depends very much on the nature of the polymer. It seems to be caused by structural changes of the dye aggregates upon polymer complex formation.

Nucleosides and Nucleotides. Part 2: Synthesis of both anomers of 1-(5′-O-phosphoryl-2′-deoxy-D-ribofuranosyl)-2(1H)-pyridone [1]†

Abstract: The two anomeric 1-(2′-deoxy-D-ribofuranosyl)-2(1H)-pyridones 6 and 7 were synthesized from 2-pyridone and 3,5-di-(O-p-toluoyl)-2-deoxy-D-ribofuranosyl chloride (2) via the di-O-p-toluoyl derivatives 3 and 4 using the mercuric halide procedure. Phosphorylation of the nucleosides 6 and 7 by bis-(2,2,2-trichloroethyl)-chlorophosphate gave the phosphate esters 8 and 9 together with some 2-(bis-[2,2,2-trichloroethyl]-phosphoryloxy)-pyridine 10, which proved to be very labile. Structure and configuration of compounds 6 to 9 were established by spectral methods, the configurations being derived from the chemical shifts of the sugar protons and the splitting patterns of the anomeric protons (‘triplet-quartet rule’). The specific rotations of 3, 4, 6, 7, 8 and 9 show that the three pairs of anomers represent exceptions to Hudson's rule of isorotation. Reductive removal of the trichloroethyl groups in 8 and 9 with zinc proceeds stepwise, yielding the phosphoro-diesters 13 and 14 and the two desired anomeric 5′-nucleotides 15 and 16. These latter were purified and characterised as the ammonium salts. Enzymatic cleavage by the 5′-nucleotidase of Crotalus adamanteus venom took place only in the ‘natural’ β-series. The ‘unnatural’ α-anomers were resistent to the enzyme. The structure of 10 was established by spectral methods and confirmed by synthesis.

Pathogenesis of Inner Ear Lesions in Acute Acoustic Trauma

Abstract: Clinical and morphological experimental data are presented concerning the development and final extent of inner-ear damage after acute noise exposure. Possible means of influencing the course of hair-cell degeneration and the theoretical and practical relevance of the findings are discussed. The results suggest modifications of the accepted concept of the pathogenesis of acute acoustic trauma.