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Eric R. Dabbs Renate Hasenbank Berthold Kastner Karl-Heinz Rak Barbara Wartusch Georg Stöffler 《Molecular & general genetics : MGG》1983,192(3):301-308
Summary A battery of immunological tests were used to investigate mutants which had been determined as lacking one or two ribosomal proteins on the basis of two-dimensional polyacrylamide gels. Proteins which were confirmed as missing from the ribosome in one or more mutants were large subunit proteins L1, L15, L19, L24, L27, L28, L30 and L33 and small subunit proteins S1, S9, S17 and S20. Cross-reacting material (CRM) was also absent from the post-ribosomal supernatant except in the case of protein S1. Since mutants lacking protein L11 have been previously described, any one of 13 of the 52 ribosomal proteins can be missing. None of these 13 proteins, except S1, can therefore have an indispensable role in ribosome function or assembly. In several mutants in which a protein was not missing but altered, it was present as several moieties of differing charge and size. 相似文献
34.
Otto D. Hensens Ray S. Dewey Jerrold M. Liesch Mary A. Napier Robert A. Reamer Jack L. Smith Georg Albers-Schönberg Irving H. Goldberg 《Biochemical and biophysical research communications》1983,113(2):538-547
Spectroscopic evidence suggests the presence of a highly strained ether ring (Fig. 1) (possibly an epoxide) in the C12-subunit of the previously determined partial structure (Fig. 2) of the major neocarzinostatin chromophore (NCS-Chrom ) which completes assignment of all the oxygens in the molecule. The main product from mercaptan treatment suggests opening of the ether ring involving the addition of one molecule of mercaptan as well as reduction of the C12-substructure, whereas a parallel two-step reduction occurs on NaBH4 treatment. Both reactions occur with rearrangement of the C12-substructure and the implication for the mechanism of action of NCS-Chrom in DNA strand scission activity is discussed. The evidence suggests a downward revision of the molecular formula for NCS-Chrom as well as minor components and by two protons. 相似文献
35.
Georg Schlayer 《Planta》1971,98(4):294-299
Summary In epidermal cells of the cytoledons of sugar beets, Beta vulgaris L., the DNA content per cell can be increased 2–4 fold by means of compensatory growth and other measures of better nutrition, by application of stronger light, or by addition of more moisture to the soil. It decreases with deviations from the optimal growth temperature (22° C) and after lack of nitrogen in the nutritive solution. Differences in DNA content, representing mainly differences in the level of endopolyploidy, result in corresponding differences in the number of plastids in the cells. 相似文献
36.
The biosynthesis of alpha factor, a mating-type-specific regulatory oligopeptide which is secreted by Saccharomyces cerevisiae cells of alpha mating type, was studied. In batch cultures only small amounts of the peptide were synthesized during the exponential growth phase. During the stationary phase, alpha factor was produced at a constant rate and accumulated in the culture medium. Inhibition of translation in wild-type cells by cycloheximide, or in mutant strains under conditions which blocked protein or ribonucleic acid (RNA) synthesis completely inhibited the production of alpha factor. These results indicate that the factor is produced by ribosomal translation of a specific messenger RNA and not by an extraribosomal mechanism of peptide synthesis. 相似文献
37.
Peter Schubert Hansjörg Teschemacher Georg W. Kreutzberg Albert Herz 《Histochemistry and cell biology》1970,22(3):277-288
Summary The intracerebral distribution patterns of 14C-morphine, 3H-dihydromorphine, and 3H-fentanyl after intraventricular injection were studied autoradiographically in rats and rabbits. The extent of permeation into the ventricular wall was measured at different times after injection. The hydrophilic morphine and dihydromorphine could be demonstrated within the tissue up to 4 hours. They seemed to be retained within the gray matter and hindered in crossing fiber bundles. On the other hand, the lipophilic fentanyl was quickly removed from the brain but remained relatively longer demonstrable within the white matter. Also, after intrathecal injection of 14C-morphine a time dependent spread from the injection site was observed. The use of autoradiography in pharmacological experiments as described was found advantageous. Thus, it is possible to correlate directly, the time course of the pharmacological effect and the respective distribution pattern of the drug applied. This may lead to better information about the probable sites of drug action. 相似文献
38.
Georg Seitz 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1970,69(2):169-185
Zusammenfassung Elektronenoptische Untersuchungen mit der Gefrierätzmethode an Augen der Normalform von Calliphora erythrocephala (Meig.) ergeben, daß im dunkeladaptierten Zustand die Rhabdomere 1–6 in den Retinulazellen dicht von Vesikeln umgeben sind, die wahrscheinlich durch Pinocytose an den Mikrovilli der Rhabdomere entstehen. Diese Bläschen fehlen im helladaptierten Zustand nahezu völlig. Die optische Dichte des umgebenden Mediums der lichtleitenden Rhabdomere wird dadurch im Dunkel-Auge herabgesetzt, was mit Hilfe der Becke-Methode im Lichtmikroskop festgestellt werden konnte.Physikalische Berechnungen mit den Gleichungen der geometrischen Optik ergeben, daß durch diese Brechzahländerung in den Sinneszellen im dunkeladaptierten Auge der physiologisch wirksame Lichtfluß in den Rhabdomeren l–6 im grünen Spektralbereich um etwa 30% erhöht werden kann.
Der Deutschen Forschungsgemeinschaft danke ich für die Gewährung eines Ausbildungsstipendiums. 相似文献
Evidence for a longitudinal pupil in the blowfly eye from studies with light and electron microscopes
Summary Eyes of the wild-type blowfly, Calliphora erythrocephala (Meig.), were investigated by using freeze-etching and the light microscope. In the dark-adapted eye a layer of vesicles 1 m thick borders on the rhabdomeres in sense cells Nos. 1 to 6. These vesicles may arise by pinocytosis at the bases of the rhabdomeric microvilli and decrease the optical density of the sense cell medium adjacent to the rhabdomeres. In the light-adapted sense cells only a few vesicles could be seen. No differences could be observed to exist between the two states of adaptation in the retinular cells Nos. 7 and 8 and in the axial retinular space.Calculations based on geometrical optics show that when rhabdomeres Nos. 1 to 6 are in the dark-adapted state they can transmit about 1.3 times more light energy than when they are in the light-adapted state. The results show the existence of a light-induced pupil reaction correlated to ultrastructural changes in the photoreceptor cells of the blowfly eye.
Der Deutschen Forschungsgemeinschaft danke ich für die Gewährung eines Ausbildungsstipendiums. 相似文献
39.
Zusammenfassung Die bemerkenswerte Sternbildung von Agrobacterium luteum Stamm A61 (Moll et al., 1967; Ahrens, 1968) ist auf polare Fimbrien zurückzuführen, die um die Sternaggregate ausgebreitet sind. Es wird angenommen, daß sich Schwärmzellen an den Fimbrien verfangen und durch Kontraktion rasch zum Stern gezogen werden. Nach elektronenoptischen Präparaten sind die Fimbrien bis zu 10,5 lang und können die beobachtete Sternbildung gut erklären. Agrobacterium luteum Stamm B14 besitzt ebenfalls lange polare Fimbrien. Beide Stämme tragen peritriche Geißeln, deren Struktur sich deutlich von den dünnen und unregelmäßigen Fimbrien unterscheidet.
The function of fimbriae in the peculiar star formation of Agrobacterium luteum
Summary The remarkable way of star formation in Agrobacterium luteum strain A61 (Moll et al., 1967; Ahrens, 1968) was found to be due to polar fimbriae which are spread around the star-shaped aggregates. It is assumed that swarmers adhere to the fimbriae and, by contraction, are swiftly pulled towards the star. As seen in electron microscopic preparations, the fimbriae are up to 10,5 long and may well explain the star formation observed. Agrobacterium luteum strain B 14 also possesses long polar fimbriae. Both strains have peritrichous flagella, the structure of which being clearly distinct from the delicate and irregular fimbriae.相似文献
40.
Summary The locomotory turns of the beetle Tenebrio molitor were recorded from free walking animals which were held in stationary position and orientation by means of a tread compensator. Striped patterns revolved around an animal elicit optomotor responses which undergo an inversion at smaller stripe widths. The position of the inversion point characterizes the resolving power of the motion detectors, and corresponds to a 6.5° average angle between the optical axes of interacting elements in the motion detecting device. This indirectly determined value is consistent with the anatomically measured 7° average angle between the axes of neighbouring ommatidia in the Tenebrio compound eye. 相似文献