Showing papers by "Ludwig Maximilian University of Munich published in 1971"

Rhodopsin-like Protein from the Purple Membrane of Halobacterium halobium

Abstract: HALOPHILIC bacteria require high concentrations of sodium chloride and lower concentrations of KCl and MgCl2 for growth. The cell membrane dissociates into fragments of varying size when the salt is removed1. One characteristic fragment—termed the “purple membrane” because of its characteristic deep purple colour—has been isolated in relatively pure form from Halobacterium halobium2. We can now show that the purple colour is due to retinal bound to an opsin-like protein, the only protein present in this membrane fragment (see also ref. 3).

Molecular Vibrations in Liquids: Direct Measurement of the Molecular Dephasing Time; Determination of the Shape of Picosecond Light Pulses

Abstract: Molecular vibrations are coherently excited by an intense light pulse of duration ${t}_{p}$. The rise and decay of the vibrational amplitude is measured with delayed pulses of the same time dependence. The molecular dephasing time $\ensuremath{\tau}$ is obtained when $\ensuremath{\tau}\ensuremath{\gtrsim}{t}_{p}$, while the shape of the light pulse is found for $\ensuremath{\tau}\ensuremath{\ll}{t}_{p}$.

Localized intracellular potentials from pre- and postsynaptic components in the external plexiform layer of an insect retina

Abstract: Intracellular potentials from the retina of the flyCalliphora erythrocephala were recorded by means of microcapillary electrodes. The type of cell examined and the exact locus of the recording sites were identified. The potentials were shown to come from the axons of visual cells (presynaptic) and from the axons of monopolar neurons (postsynaptic). The light stimulus employed consisted of step, impulse and sine-wave forms. The presynaptic responses consisted of graded depolarizing potentials while the postsynaptic responses were of a hyperpolarizing type. The former potentials had a slower time course than the postsynaptic potentials and they differed from these latter potentials by another transfer function. Problems were discussed concerning the presynaptic potential in its function as a generator potential for the postsynaptic potentials; and the transduction properties of the synapse. The synapse works as a frequency dependent amplifier with a synaptic delay of 1 msec.

Cellular dynamics of comedo formation in acne vulgaris.

Abstract: Epithelial turnover was compared on the faces and backs of normal and acne subjects using autoradiographs prepared after intra-dermal injection of tritiated thymidine, glycine and histidine. The percentage of thymidine labelled nuclei in the epidermis, sebaceous follicles and open and closed comedones was determined. The movement of glycine or histidine labelled horny cells into comedones was followed. No differences in cellular kinetics were found between acne and non-acne subjects. Turnover of the facial epidermis was almost twice as fast as of the back epidermis. Follicle labelling was similar to the contiguous epidermis. The labelling index of the comedo was much greater than in the normal sebaceous follicle. Cellular multiplication was faster in closed than in open comedones. Labelled horny cells moved in an elliptical band into the substance of the open comedo. Labelled cells eventually sloughed through the patulous orifice. This did not happen in closed comedones up to the maximum time of observation (2 months). Comedo formation is the resultant of two abnormalities: 1. increased formation of horny cells and 2. increased coherence.

Der sensorische Apparat der Spaltsinnesorgane (Cupiennius salei Keys., Araneae)

Abstract: Ein groses Einzelspaltsinnesorgan auf dem Tarsus der Spinne Cupienniua salei Keys wird elektronenmikroskopisch untersucht und mit einem kleinen tarsalen Einzelorgan sowie dem zusammengsetzten (lyriformen) Organ des Metatarsus verglichen 1 Der sog Spalt besteht aus zwei Anteilen: a) Der in der Exocuticula gelegene hat die Gestalt einer Rinne (Lange ca 51 μm, Breite ca 2,2 μm), welche an den Enden ihrer Langserstreckung flach ist und in einer Mittelzone die Exocuticula bis auf einen ca 0,23 μm starken Boden (innere Membran = Mi) durchstost Die Exocuticula bildet um den Spalt herum einen verstarkenden Rahmen mit spezifischer Anordnung der exocuticularen Lamellen b) Der in Meso- und Endocuticula gelegene Anteil offnet sich von M i aus glockenformig zur Epidermis hin 2 Der Spalt ist uberall von einer ca 0,25 μm dicken Membran (ausere Membran Ma) bedeckt, deren quantitativ wichtigste Komponente elektronenoptisch der innersten Lage der Epicuticula (dense layer) gleicht 3 Das Spaltsinnesorgan wird von zwei Dendriten innerviert Wahrend einer davon nahe Mi endet, zieht der andere durch eine Offnung in dieser bis zu M a 4 Beide Dendrite weisen dieselbe feinstrukturelle Dreigliederung auf a) Der dem Zellsoma folgende Abschnitt enthalt Tubuli und einige randstandige Mitochondrien b) Nach distal folgt eine mitochondrienreiche und tubuluslose Dendritenanschwellung c) Der somafernste Abschnitt beginnt mit einer Ciliarstruktur, deren Basalkorper in der Anschwellung liegen Er zeichnet sich durch zahlreiche von periodischen Querstrukturen miteinander verbundene Tubuli sowie das vollkommene Fehlen von Mitochondrien aus 5 Distal von der Ciliarstruktur umgibt eine gemeinsame elektronendichte Scheide die beiden Dendrite 6 In der Mittelzone ihrer Langserstreckung bildet Ma an einem in der Aufsicht tropfenformigen und leicht versenkten Flachenausschnitt eine zylinderformige Vertiefung (Tiefe ca 1 μm, o ca 0,5 μm) aus, durch deren Boden der langere Dendrit samt Scheide hindurchzieht, um als fingerformige Erhebung in dem Zylinder zu enden Das Ende dieses Dendriten zeichnet sich durch eine extra- und intrazellulare Ansammlung elektronendichter Substanz aus (Tubularkorper) 7 Eine innere und eine ausere Hullzelle (Hz 1 bzw Hz 2) umgeben die Dendrite gemeinsam Hz 1 endet distal auf Hohe der Ciliarkorper, Hz 2 reicht nahe bis zu Mi Der apikale Bereich von Hz 2 bildet eine grose, nach distal offene Invagination aus, welche von Mikrovilli und einer daraufliegenden extrazellularen Substanz gesaumt wird Elektronenoptisch vergleichbares Material findet sich in einem ausgedehnten Lakunensystem, das weiter proximal von weiteren Zellinvaginationen und erweiterten Extrazellularraumen gebildet wird 8 Der sensorische Apparat eines kleinen tarsalen Einzelorgans sowie des metatarsalen lyriformen Organs stimmt im wesentlichen mit dem des grosen tarsalen Einzelspalts uberein

Decrement-free conduction of graded potentials along the axon of a monopolar neuron

Abstract: Intracellular potentials from axons of monopolar neurons in the retina of the fly,Calliphora erythrocephala, were recorded by means of microglass capillaries. The cells studied were identified by marking with Procion-Yellow M-4R. By localizing the electrode tip, we were able to measure the distance between the recording site and the synapse. Our results have shown that: 1. the axons did not conduct discrete impulse potentials (spikes) but rather graded potentials. 2. The graded potentials were conducted without decrement. 3. The axonal responses depended on the degree of polarization of the axonal membrane. These results suggest that an active mechanism within the membrane exists which enables the decrement-free conduction of the graded potentials along the axon.

Ideas on the ultrastructural organization of the cell wall components

Abstract: The wood cell wall is composed of chemically and structurally different components. The cellulose molecules are smooth long chains, able to aggregate in longitudinal direction to compact fibrils. The polyoses consist of shorter chains with side groups and branching points so that they are not able to aggregate in such a strict order as cellulose. The orientation system of the cell wall and the behavior of isolated polyoses give reason to suppose that the polyoses are not coiled forming globular particles within the cell wall. From the ontho-genetic point of view, lignin is the last component which is incorporated into the cell wall. The different possibilities of branching resulting from the chemical characteristics of the phenylpropanone monomer enables the formation of large molecules embedding the polysaccharide elements and filling up the remaining cavities. The results of chemical and electron microscopic studies are projected into a model representing a possible ultra-structural organization of the components within the wood cell wall.

Quinones and Nicotinamide Nucleotides Associated with Electron Transfer

Abstract: Publisher Summary This chapter concentrates on the principles of function of nicotinamide nucleotides (NAN) and of menaquinone and ubiquinone in terminal substrate oxidation In mitochondria, NAN and quinones have been considered as members of the respiratory chain In particular for the NAN, this association is too limited because by the pool function the NAN is linked to the majority of cellular redox reactions In animal cells one may concentrate on the mitochondrial NAN system, whereas in protists and plants, the extramitochondrial NAD also is directly linked to the respiratory chain In prekaryotic cells, this compartmentation of NAN does not exist In this chapter, particularly interesting principles of function for the quinones are revealed In view of these various associations, the function of the coenzymes is considered both in terminal oxidation and in the substrate–substrate hydrogen transfer The molar relations between coenzymes, respiratory carriers, and dehydrogenases in mitochondria are elaborated Topochemical organization of the hydrogen-transferring coenzymes and enzymes in the mitochondrial membrane is described The redox state of nicotinamide nucleotides in mitochondria is also discussed

Decay Time of Hot TO Phonons in Diamond

Abstract: For a duration of several times ${10}^{\ensuremath{-}12}$ sec, TO modes are excited to an occupation number exceeding the equilibrium value (at 300\ifmmode^\circ\else\textdegree\fi{}K) by more than thirteen orders of magnitude. The relaxation times of these phonos are measured directly and found to agree with the known anharmonic decay at low power level. Phonon breakdown is not significant in our experiments.

Bildung der gitter des reinen bors

Abstract: On the pyrolysis of a mixture of BBr3 and H2, on tantalum wires at 900 °–1300 °C and in the absence of any foreign atoms, one obtains, at marked boundary conditions, the following boron lattices: In addition to (i) the glassy amorphous boron, also (ii) α-rhombohedral boron and (iii) II-tetragonal boron. Temporarily, these are certainly the only genuine modifications of boron formed. The I-tetragonal lattice is never formed. The so-called “I-tetragonal boron”, therefore, does not represent a modification of pure boron but a boron-rich boride, induced by doping with foreign atoms. The same probably applies to the β-rhombohedral boron, but with less certainty. Previous analysis of two-dimensional X-ray diffraction data by applying the convolution molecule method shows that nearly regular icosahedral groups are present in II-tetragonal boron.

Zur Reaktion von Azido‐Metallverbindungen mit Isonitrilen: Tetrazolato‐Komplexe mit Metall‐Kohlenstoff‐Bindung

Abstract: Die Tetrazolato-Komplexe As(C6H5)4[Au(CN4R)4] (RCH3, i-C3H7, c-C6H11, CH2C6H5, C6H5, p-CH3OC6H4), As(C6H5)4[Au(CN4CH3)2], CH3NCAuCN4CH3, (CH3NC)2Pt- (CN4CH3)2, [(C6H5)3P](RNC)M(CN4R)2 (MPd, Pt; Rc-C6H11, C6H5) und Hg(CN4CH3)2 entstehen durch Umsetzung der Azidoverbindungen As(C6H5)4[Au(N3)4], As(C6H5)4[Au(N3)2], (C6H5)3PAuN3 und [(C6H5)3P]2M(N3)2 (MPd, Pt, Hg) mit Isonitrilen unter sehr milden Bedingungen (20°). 1H-NMR-und IR-Spektren sowie die Spaltung mit HCl, die zum freien 1-substituierten Tetrazol fuhrt, beweisen das Vorliegen von Metall-Kohlenstoff-σ-gebundenen Tetrazolyl-Liganden in diesen thermisch und chemisch uberraschend stabilen Komplexen. Reaction of Azidometal Compounds with Isocyanides: Tetrazolato Complexes with Metal-Carbon Bonds The azido complexes As(C6H5)4[Au(N3)4], As(C6H5)4[Au(N3)2], (C6H5)3PAuN3 and [(C6H5)3P]2M(N3)2 (MPd, Pt, Hg) react with isocyanides under very mild conditions to give the tetrazolato complexes As(C6H5)4[Au(CN4R)4] (RCH3, i-C3H7, c-C6H11, CH2C6H5, C6H5, p-CH3OC6H4), As(C6H5)4[Au(CN4CH3)2], CH3NCAuCN4CH3, (CH3NC)2Pt-(CN4CH3)2, [(C6H5)3P](RNC)M(CN4R)2 (MPd, Pt; Rc-C6H11, C6H5) and Hg(CN4CH3)2, respectively. 1H n.m.r. and i.r. spectra as well as acid hydrolysis yielding free 1-substituted tetrazole indicate that in these thermally and chemically stable compounds the tetrazolyl ligands are bonded via C-5 to the metal.

Handling of uric acid by the rat kidney. I. Microanalysis of uric acid in proximal tubular fluid.

Abstract: Uric acid transport in the rat proximal tubule was studied by micropuncture and a new method of chemical ultramicro analysis. Under normal free-flow conditions at physiological levels of uric acid plasma concentrations a net secretion of uric acid in the proximal tubule was demonstrated. In these experiments the clearance ratio of uric acid to inulin was in the range of 0.4 which is normal in antidiuretic rats. Net reabsorption of uric acid, therefore, took place in the kidney, but certainly not in the proximal tubule as previously suggested.

Fine structure and spectral sensitivities of retinular cells in the dorsal sector of compound eyes in the dragonfly Aeschna

Abstract: 1. Retinular fine structure observed with the electron microscope and receptor potentials of single retinular cells responding to equal quantum narrow band monochromatic stimuli between 327 and 615 nm have been studied in the dorsal sector of the compound eye of Aeschna cyanea. 2. Each retinnla comprises 8 cells: 5 distal retinular cells, 2 proximal retinular cells and 1 small cell without a rhabdomere. Nevertheless, the small cell sends an axon to the lamina. In terms of microvillus directions seen in cross section the distal rhabdom has three parts with an angular difference between them of 120°. The proximal rhabdom lacks one of these three parts and is made up of two, again separated in microvillus direction by 120° (240°). 3. Basically the dorsal area of the eye has two types of receptor cells: a UV type (λmax 356 nm) and a green type (λmax 475–519 nm with a secondary peak at 356 nm). However, other response types, most likely derived from the green cells, were fairly frequently recorded: blue type, double type (green plus blue) and shifting type (alternately green and blue). 4. Close control of stimulus direction shows that green cells giving a single peak at 475–519 nm to axial or near axial light rays, develop a second peak at 458 nm when the stimulus direction deviates more strongly from axial. 5. Comparison of structural and electrophysiological evidence suggests that the distal retinular cells are the green receptors, the proximal units the UV receptors but direct evidence is needed.

Technical problems in the micropuncture determination of nephron filtration rate and their functional implications.

Abstract: The theory of a functional coupling between distal tubular fluid composition and glomerular filtration rate implies that the blockade of flow at a proximal site should lead to a marked increase of GFR. This potential alteration of steady state GFR was studied by comparing the influence of sampling from distal or proximal sites on the filtration rate of identical nephrons. During antidiuresis an average GFR of 25.2 nl/min±7.5 S.D. was found in distal collections, while proximally collected samples gave an average GFR of 34.5 nl/min±8.4 S.D. This difference of 9.3 nl/min is highly significant (p 0.05). The proximal-distal difference in nephron GFR is interpreted to indicate the operation of a tubulo-glomerular feedback control system. Thus, a true steady-state GFR probably cannot be obtained by proximal fluid collection.