Showing papers by "Heidelberg University published in 1971"
01 Jan 1971
459 citations
TL;DR: Chamberlin et al. have separated the gene 1 product from the host enzyme in Escherichia coli and show that gene 1 codes for an entirely new RNA polymerase whioii transcribes T7 DNA efficiently and exclusively compared with other templates.
Abstract: THE transcription of the late genes of phage T7 depends on the function of gene 1 of the phage1. Chamberlin et al.2 have separated the gene 1 product from the host enzyme in Escherichia coli and have shown that gene 1 codes for an entirely new RNA polymerase whioii transcribes T7 DNA efficiently and exclusively compared with other templates. Summers and Siegel3 have shown that this enzyme transcribes the late region of the T7 genome.
144 citations
TL;DR: It is the opinion that contradictory results from in vitro investigations are not yet confirmed and it is premature to subgroup the various diseases, but a comparison of the cytogenetic data, the clinical picture, as well as the course of the diseases may lead to a conceptualization of the unknown metabolic defect.
133 citations
TL;DR: In this article, total and differential elastic Σ ± p scattering cross sections have been measured in the momentum interval of 130 −180 MeV/c, from the Σ − p total cross section allowed regions for the singlet and triplet scattering lengths, applying the effective range approximation.
120 citations
TL;DR: The slow inward current displayed as inward tail current on repolarization can be inactivated by conditioning depolarization and the outward current during thedepolarization step was slightly increased, indicating that in the net outward current flowing during depolarized slow inwardCurrent and dynamic outward current overlap.
Abstract: The slow inward current in short Purkinje fibres was studied in voltage clamp experiments. The results were as follows:
1.
The slow inward current displayed as inward tail current on repolarization can be inactivated by conditioning depolarization. Thereby the outward current during the depolarization step was slightly increased. This result indicates that in the net outward current flowing during depolarization slow inward current and dynamic outward current overlap.
2.
Mn++ ions caused shortening of the action potential and blocked the slow inward current elicited either by depolarization or repolarization (inward tail current). Thereby the dynamic outward current was often increased (see 1.). An effect of Mn++ ions (7–10 mM) on the outward currents (dynamic and steady-state current) was not observed.
3.
The inward tail currents on repolarization were reduced by about one half when the extracellular sodium was replaced by cholinchloride. The residual inward tail current was further reduced on lowering the extracellular calcium concentration and it was increased on increasing the calcium concentration in the bathing solution. In Tyrode's solution (150 mM Na) lowering the calcium concentration strongly reduced the tail current, presumably by reducing the contribution of calcium ions to the tail current and/or by a rise in intracellular sodium, resulting in a decrease of the contribution of the sodium ions to the tail current. The effects of several combinations of reduction in both sodium and calcium ions on the tail current were not additive: the effect of sodium reduction was smaller at lower than at normal extracellular calcium concentrations.
4.
The instantaneous conductance of the slow inward current was found constant at potentials negative to −25 mV but could not be determined positive to −25 mV because of large overlapping outward current.
5.
The current voltage relation of the slow inward current was estimated. The current seems to be maximum between −20 mV and zero mV.
6.
The inactivation of the slow inward current was slower at low and faster at high negative membrane potentials.
7.
On clamping the potential during the action potential a rising outward current flowed which was not seen in presence of Mn++ ions indicating that this rising outward current is in fact due to decline of the slow inward current.
111 citations
105 citations
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TL;DR: In this article, a modified expansion of the electron radial wave functions is derived by means of the integral equations which correspond to the Dirac radial differential equations, and the implications of the new formulae for the analysis of experiments are discussed.
104 citations
TL;DR: In this article, a new type of proportional wire chamber with large wire distances and accurate position determination by drift time measurement is described, and the complete system with computer read out described in this article has a location accuracy of σ = 0.47 mm.
102 citations
TL;DR: The method described in detail seems to be appropriate to examine the induction of genetic defects during oogenesis by chemical agents in mice of the strains C3H and (101×C3H)F1.
Abstract: Just before ovulation we treated 10–12-week-old female mice of the strains C3H and (101×C3H)F1 with 2.3.5.-triethyleneimonobenzoquinone-1.4 (T), cyclophosphamide (C) and methotrexat (M). The chromosome analysis took place shortly after ovulation at the time of metaphase II. The method described in detail seems to be appropriate to examine the induction of genetic defects during oogenesis by chemical agents.
96 citations
TL;DR: The formation of calcite, aragonite, dolomite, hydromagnesite, and nesquehonite in speleothems of a small cave within dolostone may be compared with the formation of these carbonate minerals in much larger environments in which evaporation exceeds precipitation as discussed by the authors.
Abstract: The formation of calcite, aragonite, dolomite, hydromagnesite, and nesquehonite in speleothems of a small cave within dolostone may be compared with the formation of these carbonate minerals in much larger environments in which evaporation exceeds precipitation (salt lakes, tropical lagoons, sebkhas etc...). In all cases the formation and diagenetic alteration is mainly governed by the Mg/Ca-ratio of the solutions, from which precipitation (or transformation) takes place.
93 citations
TL;DR: The Schmeckhaare der Fliege Phormia terraenovae enthalten funf Rezeptorzellen (vier Kontaktchemo-and eine Mechanorezeptorselle), die von zwei Hullzellen unter Aussparung von Lymphraumen (Vakuole) umgeben sind.
Abstract: Die Schmeckhaare der Fliege Phormia terraenovae enthalten funf Rezeptorzellen (vier Kontaktchemo- und eine Mechanorezeptorzelle), die von zwei Hullzellen unter Aussparung von Lymphraumen („Vakuole“) umgeben sind. Die Rezeptorzellen gliedern sich in Axon, Zellkorper und Dendrit, der aus Innenglied, Ubergangsabschnitt und Ausenglied besteht. Der Ubergangsabschnitt hat die 9+0-Struktur der modifizierten Cilien mit zwei Basalkorpern. Im Plasma der Ausenglieder sind nur Mikrotubuli zu erkennen. Die Ausenglieder der Kontaktchemorezeptoren ziehen durch die rohrenformige Dendritenscheide und den Kanal I des Haarschafts bis zu einem Porus in der Haarspitze, durch den sie mit den Schmeckstoffen in Kontakt kommen (Ort der Primarprozesse). Das Ausenglied der Mechanorezeptorzelle enthalt einen tubularen Korper und setzt an der Haarbasis an. Die Hullzelle II (tormogene Zelle) bildet zum grosen Sensillenlymphraum hin ein stark gefaltetes Membransystem aus. Der Feinbau wird in Beziehung zur Funktion der Schmeckhaare gesetzt.
TL;DR: The histological structures of the rapidly and slowly adapting mechanoreceptors of group II afferents (RA- and SA-receptors) in the hairless skin of the cat's hind foot showed that structure and function could be correlated as follows.
TL;DR: In frog atria, time and voltage dependence of inactivation and reactivation of fast transient Na current were studied using the sucrose-gap voltage clamp technique using two variables which both decrease on depolarization but largely differ in the rate constants.
Abstract: 1.
In frog atria, time and voltage dependence of inactivation and reactivation of fast transient Na current were studied using the sucrose-gap voltage clamp technique. Experiments were done at 4–7° C.
2.
Fast inward current inactivated by conditioning depolarizing clamps. The relation between steady-state inactivation and membrane potential is represented by an S-shaped curve similar to that observed in squid axon. At the resting level the availability of the Na-carrying system is about 60–70%.
3.
During depolarizing clamps inactivation of Na current follows an approximately exponential time course with time constants between 1.5 and 8 msec.
4.
Recovery from inactivation (reactivation) is much slower than development of inactivation. Time constants between 100 and 600 msec were observed during the recovery process following a repolarization or a hyperpolarization.
5.
A ratio between the time constants of inactivation and reactivation in the order of 1∶50 was found when the two processes were studied at the same potential level.
6.
In the frog atrial action potential the slow reactivation of the Na system is reflected by a relative refractory period reaching far beyond full repolarization.
7.
Assuming that the slow course of Na reactivation is an inherent feature of Na kinetics, the inactivation variable (h) of the Hodgkin-Huxley theory (1952d) seems inadequate to describe the inactivation-reactivation process in frog atria. Formally fast inactivation and slow reactivation could be accounted for by replacing the variableh with two variables which both decrease on depolarization but largely differ in the rate constants.
TL;DR: The peak amplitude of the contraction increased with the size of the depolarizing step in the range of the membrane potential at which the calciumCurrent should be small or zero, which suggests that in addition to the calcium current another effect of depolarization controls the contraction.
Abstract: The membrane potential of the guinea-pig's papillary muscle was controlled by a voltage clamp technique which employs one sucrose gap and one intracellular microelectrode. Both the membrane potential and the membrane current were recorded together with the contraction. The steady-state contractions were obtained after 6–8 contractions. The difference between the steady-state contractions and the succeeding test contractions was considered to be due to the difference in the trigger action between the conditioning and the test pulses. The following results were obtained: 1. when the test pulses were appropriately shortened so that a large tail of inward current flowed after the repolarization step, the contraction was augmented. This paradoxical increase of the contraction can be explained by assuming a direct action of the slow inward current on contraction. 2. The peak amplitude of the contraction increased with the size of the depolarizing step in the range of the membrane potential at which the calcium current should be small or zero. This suggests that in addition to the calcium current another effect of depolarization controls the contraction. 3. The rate of rise of contraction seemed to be determined by the calcium current which was maximum at a depolarization to +10 mV. At this level the slow inward current also reached the maximum. With further increase of the depolarization the rise of the contraction and the slow inward current were decreased. 4. During a series of the pulses the positive inotropic effect (staircase) was the more pronounced the larger the depolarization. This holds true for depolarization up to +70 mV. The potentiation occurred in spite of decrease of the slow inward current. It seems necessary to postulate a potentiating process which is dependent on the amplitude of the depolarization.
TL;DR: The nature of the basic surface oxides on carbon was studied by chemical reactions, e.g. methylation with methanol/sulphuric acid.
TL;DR: In this article, the sums of approximate internal conversion coefficients for the (N + O + · · ·) shells are presented for all values of atomic number from Z = 37 to Z = 100.
TL;DR: In this article, the shape dependence of various terms appearing in the nuclear droplet model of Myers and Swiatecki is studied and a variety of shape parameterizations are used to calculate nuclear saddle point shapes corresponding to the fission barrier.
TL;DR: In this paper, the authors compare the spectra of the title compounds 6 and 8 with those of similar polycyclic 9-acridone derivatives, and show that the exceptionally large bathochromic shift of the longest wavelength band of the diketone 8 corresponds to its nonplanar structure, which impairs the resonance stabilisation of the electronic ground state.
Abstract: Die UV-Spektren der Titelverbindungen 6 und 8 werden mit den Spektren ahnlicher polycyclischer Acridon-(9)-Abkommlinge verglichen. Mit zunehmender Erweiterung des Konjugationssystems treten bathochrome Verschiebungen der langstwelligen Absorptionsbanden der Acridon-ahnlichen Spektren auf. Die zugehorigen protonierten Spezies absorbieren durchweg bei langeren Wellen, was auf das Vorliegen sauerstoff-protonierter Spezies des Typs 14 hinweist. Die ausergewohnlich grose bathochrome Verschiebung der langstwelligen Bande des Diketons 8 beruht auf seiner nicht-planaren Struktur, die die Mesomeriestabilisierung des elektronischen Grundzustandes beeintrachtigt.
Heteropolycyclic Compounds of the Triangulene-type, I. 8.12-Dihydro-4H-benzol[1.9]quinolizino[3.4.5.6.7-defg]acridine-4.8.12-trione and 5.9-Dihydroquino[3.2.1-de]acridine-5.9-dione
The u.v. spectra of the title compounds 6 and 8 are compared with the spectra of similar polycyclic 9-acridone derivatives. With increasing conjugation of the system bathochromic shifts of the longest wavelength absorption bands of the acridone-like spectra appear. All corresponding protonated species absorb at longer wavelength, which points to the occurence of oxygen-protonated species of type 14. The exceptionally large bathochromic shift of the longest wavelength band of the diketone 8 corresponds to its non-planar structure, which impairs the resonance stabilisation of the electronic ground state.
TL;DR: Most coralline algae contain considerably more magnesium in their calcitic skeletons than can be explained by the shift in their x-ray diffraction peaks as mentioned in this paper, and part of this excess magnesium is explained by local concentrations of higher magnesian calcite within the skeleton.
Abstract: Most coralline algae contain considerably more magnesium in their calcitic skeletons than can be explained by the shift in their x-ray diffraction peaks. Part of this excess magnesium is explained by local concentrations of higher magnesian calcite within the skeleton. Utilization of these higher magnesian phases may have generic and ecologic implications. Data also suggest that an additional phase, perhaps brucite, may be responsible for the remainder of the excess magnesium.
TL;DR: In this article, the isotopic fractionation of mixed-isotope spikes is corrected by using the fact that the fractionated, measured isotope ratios of a critical three isotope mixture lie exactly on a tie line that connects the true compositions of spike and normal element.
TL;DR: In this paper, it was shown that the free enthalpies of activation ΔGmath image for rotation about the Cαaryl bond vary from < 7.5 to 15 kcal/mole (Tables 1 and 2).
Abstract: 1H n.m.r. spectra and semi-empirical calculations of strain energies have shown that the ground state of the toluene derivative 3 is represented by conformation a (R CH3), the α-methine proton of which eclipses one of the o-methyl groups. Accordingly, the existence of two rotamers, e.g.15E and 15Z, was demonstrated in the case of the toluenes 15, 16, 17, 18, and 19 synthesized with two unequal o- or m-substituents. The measured equilibrium ratios of rotamers (Table 2) are in good agreement with the results of the calculations for 15 and 16. - The free enthalpies of activation ΔGmath image for rotation about the Cαaryl bond vary from < 7.5 to 15 kcal/mole (Tables 1 and 2). Barriers of this kind were reproduced with sufficient accuracy by calculations for 3, 15, and 16 if the Cαaryl bond length and the bond angles were assumed to be flexible, i.e., if they were optimized for each rotational arrangement. The transition state turned out to be a conformation of type d, the CαH bond of which is arranged perpendicular to the benzene ring; potential energy curves for Cαaryl rotation are given in Fig. 3 and 4. Calculations presupposing a rigid molecular geometry erroneously result in conformation c as the transition state and yield barriers which are much higher than the measured ones.
01 Jan 1971
TL;DR: In 1883 Schimper wrote in a footnote: „Sollte es sich definitiv bestatigen, dass die Plastiden in den Eizellen nicht neu gebildet werden, so wurde ihre Beziehung zu dem sie enthaltenden Organismus einigermassen an eine Symbiose erinnern“.
Abstract: In 1883 Schimper wrote in a footnote: „Sollte es sich definitiv bestatigen, dass die Plastiden in den Eizellen nicht neu gebildet werden, so wurde ihre Beziehung zu dem sie enthaltenden Organismus einigermassen an eine Symbiose erinnern. Moglicherweise verdanken die grunen Pflanzen wirklich einer Vereinigung eines farblosen Organismus mit einem von Chlorophyll gleichmassig tingierten ihren Ursprung“.
01 Jan 1971
TL;DR: Although edema was observed in all phases of the encephalopathy, changes in the blood vessels, formation of platelet thrombi, and alterations of the Purkinje cells and their dendrites warranted special attention.
Abstract: Experimental lead encephalopathy was produced in developing rats. The cerebellar changes that developed were studied by light and electron microscopy. Although edema was observed in all phases of the encephalopathy, changes in the blood vessels, formation of platelet thrombi, and alterations of the Purkinje cells and their dendrites warranted special attention. The lead and calcium content of the brain and of the blood in the lead poisoned and control groups were determined chemically. The results are discussed from a morphological point of view and a hypothesis of their pathogenesis is presented.
TL;DR: In this paper, the 1.8-Bis-aryl-athinyl-naphthaline (1a−1e)-naphthynyl (naphTH) interaction was investigated.
Abstract: Fur die 1.8-Bis-arylathinyl-naphthaline 1a–1e, deren Darstellung beschrieben wird, lassen die Spektren (UV, IR, 1H-NMR) keine starkere Wechselwirkung zwischen den parallel orientierten Dreifachbindungen erkennen. Die Reaktivitat dieser Diacetylene ist dagegen weitgehend durch eine solche Wechselwirkung bestimmt: Thermisch und photochemisch werden aus 1 die Benzofluoranthene 2 erhalten; bei der Bestrahlung von 1e entsteht das Azulen 3. Katalytische Hydrierung von 1 fuhrt uberwiegend zu Produkten mit Acenapthen-Skelett. Eisenpentacarbonyl reagiert mit 1 nicht zu den Cyclobutadien-Komplexen 6, sondern zu Acecyclon-eisentricarbonylen (7a–7c). Mit Quecksilber(II)-acetat werden Indeno[2.1-a]-phenalene (8, 10, 11 und 15) erhalten; der Mechanismus dieser Reaktion wird diskutiert.
Intramolecular Interactions of Triple Bonds, V. Parallel Triple Bonds: 1.8-Bis(arylethynyl)naphthalenes
For 1.8-bis(arylethynyl)naphthalenes 1a–1e, the preparation of which is described, no evidence for any stronger triple bond interaction is obtained from u. v., i. r., and 1H n.m.r. spectra. On the other hand, chemical reactivity of these compounds is determined by such an interaction: In thermal and photochemical reactions benzofluoranthenes 2 are obtained from 1; irradiation of 1e yields the azulene 3. Catalytic hydrogenation of 1 results mainly in the formation of products with acenaphthene skeleton. With iron pentacarbonyl acecyclone tricarbonyls 7a–7c are obtained instead of the cyclobutadiene complexes 6. With mercury diacetate indeno[2.1-a]phenalenes 8, 10, 11 and 15 are formed; the mechanism of this reaction is discussed.
TL;DR: In this paper, an elektrophile, ungesattigte Partner in a stereospezifischen 2 + 2-cycloaddition is described, and thermolyses and photolyses of some of the cycloadducts are reported.
Abstract: Tetramethoxy-athylen (1) addiert sich in hohen Ausbeuten an elektrophile, ungesattigte Partner in einer stereospezifischen 2 + 2-Cycloaddition. Die Thermolyse und Photolyse einiger Addukte wird beschrieben.
Tetramethoxyethylene, VII. 2 + 2-Cycloadditions to Tetramethoxyethylene
Tetramethoxyethylene (1) readily adds to electrophilic unsaturated compounds to form 2 + 2-cycloadducts in high yield with retention of stereochemistry. Thermolyses and photolyses of some of the cycloadducts are reported.
TL;DR: The external asymmetric Strecker synthesis of α-methyl-aminoacids has been shown to be stereospecific as it gives the corresponding [R; R]-enantiomer of 2 as discussed by the authors, which is available in large quantities as an intermediate in the chloramphenicol synthesis.
Abstract: Die [S]-α-Methyl-aminosauren 16, 17 und 18 lassen sich mit Hilfe des [4S; 5S]-(+)-5-Amino-2.2-dimethyl-4-phenyl-1.3-dioxans (des [S; S]-Enantiomeren von 2), das in grosen Mengen bei der Chloramphenicol-Synthese als Zwischenprodukt anfallt, in 80–90proz. Ausbeute nach Strecker synthetisieren. Da diese asymmetrische Strecker-Synthese mit dem [R; R]-Enantiomeren von 2 zu den entsprechenden [R]-α-Methyl-aminosauren fuhrt, ist sie stereospezifisch. Die in der ersten Stufe der Synthese auftretenden Aminonitrile 7, 8 und 9, in denen das Chiralitatszentrum der Endprodukte bereits gebildet ist, zeigen beim Stehenlassen in Losung eine asymmetrische Umlagerung 1. Art. Das Gleichgewicht der Diastereomeren, das sich nach 24 Stdn. eingestellt hat, wird NMR-spektroskopisch und chemisch quantitativ bestimmt. Durch Verseifung der Aminonitrile sofort nach ihrer Entstehung wird bewiesen, das das neue Chiralitatszentrum durch asymmetrische Synthese gebildet wird. Die Konstitutionen der Zwischenprodukte werden aufgeklart und die Mechanismen der ausgefuhrten Reaktionen diskutiert. Die allgemeine Anwendbarkeit der Synthese wird untersucht.
Asymmetric Synthesis, II. The External Asymmetric Strecker Synthesis of α-Methyl-aminoacids
The [S]-α-methyl-aminoacids 16, 17 and 18 can be obtained in 80–90% yields by the Strecker synthesis from [4S; 5S]-(+)-5-amino-2.2-dimethyl-4-phenyl-1.3-dioxane (the [S; S]-enantiomer of 2), which is available in large quantities as an intermediate in the chloramphenicol synthesis. This asymmetric Strecker synthesis is stereospecific as it gives the corresponding [R]-α-methyl-aminoacid when it is carried out with the [R; R]-enantiomer of 2. The aminonitrils 7, 8 and 9 of the first step of the synthesis containing the centre of chirality of the end products, undergo a first order asymmetric transformation standing in solution. The equilibrium of diastereomers being formed after 24 hours is n.m.r. spectroscopically and quantitatively established. Saponification of aminonitrils immediately after they have been formed indicates that the new centre of chirality is fromed by asymmetric synthesis. The constitutions of intermediate products have been established and the reaction mechanisms discussed. The general applicability of the synthesis is under investigation.
TL;DR: To maximaze steady-state per capita consumptions, goods should be valued at their "synchronized labor requirement costs", which are shown to deviate from Marx's schemata of "values" but to coincide with bourgeois prices calculated at dated labor requirements, marked-up by compound interest.
Abstract: To maximaze steady-state per capita consumptions, goods should be valued at their “synchronized labor requirement costs”, which are shown to deviate from Marx's schemata of “values” but to coincide with bourgeois prices calculated at dated labor requirements, marked-up by compound interest, at a profit or interest rate equal to the system's rate of exponential growth. With capitalists saving all their incomes for future profits, workers get all there is to get. Departures from such an exogenous, or endogenous, golden-rule state are the rule in history rather than the exception. In the case of exponential labor-augmenting change, it is shown that competitive prices will equal historically embodied labor content.
TL;DR: This communication recommends practical procedures for the dominant lethal assay, and indicates how these can be integrated in routine toxicological practice.
Abstract: GENETIC hazards from drugs and chemical pollutants are now widely recognized and appropriate, sensitive and economic mammalian methods for detecting and measuring mutagenic effects of chemicals have been developed. These methods are relevant to man1 and include in vivo cytogenetics, host-mediated assay, and dominant lethal assay; sub-mammalian systems are generally considered to be of ancillary value only. The Advisory Panel on Mutagenicity of Pesticides1 and the Food and Drug Administration Advisory Committee on Protocols for Safety Evaluation2 have recommended that pesticides and food additives should be tested for mutagenicity in mammalian systems before registration. This communication recommends practical procedures for the dominant lethal assay, and indicates how these can be integrated in routine toxicological practice.