bluuebunny/crossref_metadata_2025 huggingface dataset:
Transport and Processing of Ribosomal RNA in Plant Cells after Treatment with Cycloheximide
Authors: Gebauer Hans-Ullrich , Seitz Ursula , Seitz Ulrich
Published: August 2018

In freely suspended cells of parsley (Petroselinum crispum ) protein synthesis is inhibited nearly totally by 5 /ug/ml cycloheximide within 10 min. This very low dose has a slight effect on the rRNA synthesis too. During an incubation period of 60 min with [32P] orthophosphate in the presence of the inhibitor (5 /ugjml) at least 65 - 70% mature rRNA are synthesized compared with the control. After 120 min the synthesis is progressively reduced to 60 - 65%, and after 240 min to 30-40% .

Cycloheximide causes a delay of the processing of the precursor RNA species leading to an accumulation of these components. In addition to the 2.3 x 10® daltons RNA, normally detectable in pulse experiments, two further precursor molecules do emerge which under normal circumstances apparently are shortlived. Their molecular weights are 2.0 x 10® and 0.9 x 10® daltons.

The pulse-chase technique and cell fractionation into nuclear and ribosomal parts enables us to demonstrate a rapid transfer of labelled 18S and 25S RNA during a 15 min chase treatment to the mature cytoplasmic ribosomes. Under these conditions no differential transport of the two components takes place.

The cells possess a pool of proteins. Therefore the formation of RNP-particles or ribosomes respectively and the transport from the nucleus to the cytoplasm are independent from protein synthesis for some time
Über die Bedeutung paranodaler Strukturen für die Impulsregeneration am Ranvier’schen Schnürring / About the Importance of Paranodal Structures of the Ranvier Node for the Impulse Regeneration
Authors: Müller-Mohnssen Helmuth , Tippe Armin , Hillenkamp Franz , Unsold Eberhard
Published: August 2018

The site of the pulse regeneration in myelinated nerve is generally assumed to be the unmyelinated part of the axon membrane in the Ranvier node. To check this, a micro-irradiation technique using laser pulses (λ = 347 nm, t = 2 0 ns) was used to produce morphological lesions of about 1 /(m diameter in various regions of the Ranvier node. The electro-physiological functions were monitored parallel to the irradiation. Depending on the localization of the lesions two types of changes in these functions were observed:

1. If a definite site in the paranodal myelin sheath was damaged without affecting the axon, an action potential could no longer be elicited, although the resting potential as well as the stationary current-voltage behaviour remained unchanged.

2. A damage of the axon resulted in a break down of membrane potential and resistance. In most of the cases the excitability recovered after spontaneous or current induced restitution of the membrane resting potential and resistance.

These observations indicate, that structures in the paranodal region are vital for the Na+-activation and inactivation. The membrane potential and stationary current-voltage behaviour can be attributed to the axon membrane. A new hypothesis concerning the mechanism of the Na+-activationinactivation process is suggested
Carotinoide in Zygaena -Arten (Lepidoptera)/ Carotenoids in Zygaena Species (Lepidoptera)
Authors: Bornefeld T , Czygan Franz-C
Published: August 2018

Species of Zygaena (Lepidoptera) have been fed with leaves of Lathyrus pratensis rich in chlorophylls and carotenoids. The metabolism of the pigments was followed in eggs, larvae, pupae, and imagines of the insects. No chlorophylls, only lutein - the main carotenoid of the food plants - was stored in the animals. Traces of α-zeacarotene, absent in plants, could be found in eggs and larvae
The Inhibition of Carotenoid Biosynthesis in Green Algae by SANDOZ H 6706: Accumulation of Phytoene and Phytofluene in Chlorella fusca
Authors: Kümmel H. W. , Grimme L. H.
Published: August 2018

Prolonged cultivation of the green alga Chlorella fusca under heterotrophic conditions and in the presence of sub-lethal concentrations of SAN H 6706 (4-chloro-5-(dimethylamino)-2-(α,α,α-tri-fluoro-m-tolyl)-3 (2H)-pyridazinone) leads to an accumulation of phytoene and phytofluene. The content of chlorophylls and coloured carotenoids of the cells treated with this herbicide, compared with normal untreated cells, is diminished by about 90% and 95% respectively, but the total amount of carotenoids, including colourless phytoene and phytofluene, is increased by 65%. This suggests that SAN H 6706 causes increased accumulation of carotenoids by eliminating a biosynthetic control mechanism, so that the endproducts of the biosynthetic chain no longer control the rate of precursor formation.
Effect of Zinc and Cadmium on δ-Aminolevulinate Dehydratase of Red Blood Cells in Protecting against Enzyme Losses during Storage
Authors: Hampp R. , Kriebitzsch C.
Published: August 2018

The effect of zinc and cadmium on δ-aminolevulinate dehydratase of bovine erythrocytes stored at - 30 °C for different times was determined. The results show a. storage of erythrocytes leads to an enhancement of the enzyme activity, which after six weeks is 165% (500 μм ZnCl2) respectively 220% (100 μм CdCl2) for red blood cells of calves, and after four weeks is 420% respectively 450% (same concentrations) for red blood cells of adult cattle, b. the older the samples are, the higher is the metal concentration, needed for activation.
On the Structure of Lignin from Soybean Cell Suspension Cultures
Authors: Nimz H. , Ebel J. , Grisebach H.
Published: August 2018

Treatment of soybean cell cultures according to the Björkman-procedure yields a “milled wood lignin” (MWL), which has been shown to be a hardwood lignin by thermofractography and carbon-13-NMR spectroscopy. The 13C-NMR spectrum of this acetylated lignin indicates that this lignin contains relatively high amounts of cinnamyl alcohol and p-hydroxyphenyl groups compared with other typical hardwood lignins. The 13C-spectrum of the acetylated MWL also indicates the presence of carbohydrate components, which are apparently very tightly bound to the lignin.
Reaction of Glutathione with Conjugated Carbonyls
Authors: Esterbauer Hermann , Zöllner Helmward , Scholz Norbert
Published: August 2018

1. GSH reacts with conjugated carbonyls according to the equation: G SH+R-CH=CH-COR⇆R-CH(SG)-CH2-COR. The forward reaction follows second order, the reverse reaction first order kinetics. It is assumed that this reaction reflects best the ability of conjugated carbonyls to inactivate SH groups in biological systems.

2. The rate of forward reaction increases with pH approx. parallel with αSH. Besides OH- ions also proton donors (e. g. buffers) increase the rate. The catalytic effect of pH and buffer is inter­ preted in view of the reaction mechanism.

3. The equilibrium constants as well as the rate constants for forward (k1) and reverse reaction show an extreme variation depending on the carbonyl structure. Acrolein and methyl vinyl ketone (kt = 120 and 32 mol-1 sec-1 , resp.) react more rapidly than any other carbonyl to give very stable adducts (half-lives for reverse reaction 4.6 and 60.7 days, resp.). Somewhat less reactive are 4-hydroxy-2-alkenals and 4-ketopentenoic acid (k1 between 1 and 3 mol-1 sec-1), but they also form very stable adducts showing half-lives between 3.4 and 19 days. All other carbonyl studied react either very slowly (e. g. citral, ethly crotonate, mesityl oxide, acrylic acid) or form very labile adducts (crotonal, pentenal, hexenal, 3-methyl-butenone). Comparing biological activities of con­ jugated carbonyls their reactivity towards HS (k1) and the stability of the adducts must be considered.
The Biphasic Ca2+-Uptake by the Fragmented Sarcoplasmic Reticulum
Authors: Mermier Pierre , Hasselbach Wilhelm
Published: August 2018

The non-equilibrium dialysis has been used for kinetic studies of ATP dependent calcium up­ take by the sarcoplasmic reticulum. The uptake displays two phases, which are defined as fast and slow uptake. The former is an exponential function of time, with a half-life time of approximately 15-20 sec, the latter presents the characteristics of an autocatalytic reaction. The fast uptake is characterized by its amplitude, the slow uptake by its rate. Compared with the fast up­ take, the slow uptake requires higher amounts of Mg2+ or ATP, and is more sensitive to pH variations and aging. The reasons which formerly prevented the resolution of the second phase from the first are discussed. It is concluded that the fast uptake is not a simple binding reaction, and that the slow uptake is more sensitive to changes by the vesicular membrane.
Ein Gerät zur Probenentnahme in Ein-Sekunden-abständen bei Photosyntheseexperimenten / An Apparatus for Sampling at One Second Intervals in Photosynthesis Experiments
Authors: Bornefeld T. , Kaiser W. , Kleinschnitz W.
Published: August 2018

A device is described which allows withdrawing of samples of 1 to 2 ml ± 0.03 to 0.06 ml from a lollipop at 1 sec intervals.
Isolierung und Eigenschaften der Zellhiille der Griinalge Chlorella fusca / Isolation and Properties of the Cell Envelope of the Green Alga Chlorella fusca
Authors: Hülsen W. , Kubin D.
Published: August 2018

Chlorella cell envelopes were isolated by a mechanical procedure. The obtained morphological structure shown in an EM-picture has a mean density of ρ = 1.42. A characteristic chemical property of the envelope is the percentage of mono-and di-unsaturated C18-fatty acids which is considerably higher than that of intact cells. With 14C labelled sugars a selectivity of the hexose uptake could be shown, galactose uptake amounting only to about one fifth that of glucose and mannose. The uptake shows a temperature maximum. Part of the 14C registered after a 30 min uptake peroid is released by high concentration of unlabelled glucose, 20% are irreversibly fixed.
Spectrometric and Biological Data of 1,N6-Ethenoadenosine 3',5'-Cyclic Monophosphate
Authors: Wombacher Helmut , Reuter-Smerdka Monika
Published: August 2018

Spectroscopic properties of 1,N6-ethenoadenosine cyclic 3′,5′-monophosphate were studied and compared with cyclic adenosine 3′,5′-monophosphate. Data of nuclear magnetic resonance*, mass-, ultraviolet-, and fluorescence spectroscopy were given. Additionally biochemical activity was tested in protein kinase system of beef adrenals. No significant biological difference between cyclic adenosine 3′,5′-monophosphate and its fluorescent analog has been found.
Photoreactions of Cytochrome b6 and Cytochrome f in Chloroplast Photosystem I Fragments
Authors: Böhme H
Published: August 2018

Photosystem I fragments were prepared by digitonin treatment of spinach chloroplasts. The mid­point potential of cytochrome b6 in the fragments is close to 0 V, showing a one electron transition. No cytochrome b559 was detectable, neither in difference absorption spectra nor in light-induced absorbance changes. In the absence of added cofactors only cytochrome b6 photoreduction can be observed. This photoreduction is stimulated by ferredoxin. Ferredoxin-NADP+ reductase appears not to be involved in cytochrome b6 reduction. Photooxidation of cytochrome b6 is dependent on plastocyanin addition and inhibited by DBMIB, a plastoquinone antagonist. Addition of plastocyanin restores cytochrome f photooxidation as well, reacting quite specifically in about equimolar concentrations to bound cytochrome f. The stimulation of cytochrome f oxidation is abolished by an antibody prepared against plastocyanin, indicating a surface location of plastocyanin in digitonin treated membranes.

Biphasic kinetics of dark-reduction of cytochrome f by ascorbate indicate that part of this cyto­chrome f is relatively inaccessible in the membrane. After preillumination a monophasic reduction is observed and the slowly oxidized component is absent. Illumination in the presence of plastocyanin causes a fast and complete reduction of cytochrome f, suggesting equilibration of cyto­chrome f with added plastocyanin, residing in the membrane surface. It appears that actinic light causes conformation and/or structural changes in the membrane of these digitonin fragments, influencing cytochrome f accessibility.
The Chlorophyll aII Reaction in Trypsin-Treated Spinach Chloroplasts in the Presence of Potassium Ferricyanide
Authors: Döring Günter
Published: August 2018

In trypsin-treated spinach chloroplasts there is no linear electron flow from water to potassium ferricyanide. The chlorophyll aII reaction, however, is still active but insensitive to 3-(3,4-dichloro-phenyl)-1,1-dimethylurea. From this we conclude that ferricyanide and trypsin together stimulate a mini-cycle in photosystem II.
Redundante Nucleotid-Sequenzen in DNA aus Weizen / Redundant Nucleotide-Sequences in DNA from Wheat
Authors: Kern Hartmut , Grübler Joachim
Published: August 2018

DNA from dormant and germinated embryos exhibit differences in the kinetics of reassociation of thermal denatured nucleic acid. Within 24 h of germination a reduction of the renaturation, expressed as Cot1/2 of the redundant fraction, is detectable.
Isolation o f β, β-Caroten-2-ol from an Insect, Cerura vinula (Lepidoptera)
Authors: Kayser Hartmut
Published: August 2018

The monohydroxy carotenoid from the moth Cerura vinula has been shown to be β,β-caroten-2-ol on the basis of electronic, infrared, proton magnetic-resonance, and mass spectra. On acid treatment in the presence of molecular oxygen this carotenoid is dehydrogenated to 4′,5-retro-β, β-caroten-2-one. The identification of β, β-caroten-2-ol by its retro product, its time course of acetylation, and its chromatographic properties relative to β, β-caroten-3-ol and β, β-caroten-4-ol is discussed.

This is the first demonstration of a 2-hydroxylated carotenoid in an insect. Implications on the biogenesis of this pigment are considered.
Kinetic Properties of Mg, Ca ATPase from Various Escherichia coli Mutants
Authors: Ahlers Jan , Günther Theodor , Schrandt Irene
Published: August 2018

The ATPase is not lacking in the ATPase mutants DL 54 and AN120 but has very different kinetic properties including a higher Cl- optimum and higher Km values for MgATP. In AN 120, the ATPase activity also has a higher Mg2+ optimum.
Formation of H -Addition Radicals in Adenine Derivatives
Authors: Zehner H. , Flossmann W. , Westhof E.
Published: August 2018

The formation of H-aduition radicals in monocrystals of 9-methyl adenine, deoxyadenosine monohydrate, and adenosine hydrochloride by irradiation with X-rays has been studied using ESR spectroscopy. In 9-methyl adenine and adenosine-HCl, hydrogen atoms add exclusively to position C8 of the imidazole part of the purine ring. On the other hand, in deoxyadenosine · H2O crystals, H-addition radicals at position C2 of the pyrimidine part of the purine ring occur together with H-addition radicals at position C8. Both radicals could be isolated by using their differential stability under warming or illumination with light. The C8-addition radical is characterized by two equivalent β-protons of 38.0 ± 0.5 G and the C2-addition radical by two non-equivalent β-protons of 34.0 ±1.0 and 50.0 ± 1.0 G. The nitrogen splittings perpendicular to the purine ring are 27.0 and 6.6 G for the C2-addition radical and 20.5 and 9.2 G for the C2-addition radical. The coupling constants of both radicals are in agreement with INDO calculations. It is further shown that the added hydrogen atom comes partly from the hydrogen bonding scheme and partly from the non­exchangeable hydrogens for the C8-addition radical. Together with additional experiments on polycrystalline samples, these results lead to the conclusion that hydrogen atoms add non-selectively to C2 and C8 of the neutral molecules, whereas protons add predominantly to C8 of anion radicals. This is supported by Hückel molecular orbital calculations.
Coupling Factor Adenosine-5′-triphosphatase from Rho do spirillum rubrum: A Simple and Rapid Procedure for Its Purification
Authors: Lücke Friedrich-Karl , Klemme Jobst-Heinrich
Published: August 2018

When photosynthetic membranes from Rhodospirillum rubrum, devoid of loosely bound small molecules and proteins, were passed through a French-pressure cell, the enzyme adenosine-5′-triphosphatase (EC 3.6.1.3.) (ATPase) was released into the soluble fraction.

The solubilized ATPase was purified to homogeneity. In many respects it behaved like the enzyme purified by other workers, but it also hydrolyzed Mg-ATP with a small, but significant rate. Furthermore, it was much more stable.

Maximal restoration of photophosphorylation in ATPase-depleted membranes was achieved by addition of about 1 mg purified ATPase per mg bacteriochlorophyll. For reconstitution of NAD+- photoreduction, about half of this amount was saturating.
Inhibition of Electron Transport on the Oxygen-Evolving Side of Photosystem II by an Antiserum to a Polypeptide Isolated from the Thylakoid Membrane
Authors: Schmid Georg , Menke Wilhelm , Koenig Friederike , Radunz Alfons
Published: August 2018

A polypeptide fraction with the apparent molecular weight 11000 was isolated from stroma-freed chloroplasts from Anthirrhinum majus. An antiserum to this polypeptide fraction inhibits photosynthetic electron transport in chloroplasts from Nicotiana tabacum. The relative degree of inhibition is pH dependent and has its maximum at pH 7.4. The maximal inhibition observed was 93%. The dependence of the inhibition on the amount of antiserum yields a sigmoidal curve which hints at a cooperative effect. A calculation of the Hill interaction coefficient gave the value of 10. The inhibition occurs on the water splitting side of photosystem II between the sites of electron donation of tetramethyl benzidine and diphenylcarbazide. Tetramethyl benzidine donates its electrons before the site where diphenylcarbazide feeds in its electrons. Analysis of the steady state level of the variable fluorescence also indicates that the inhibition site is on the water splitting side of photosystem II. Tris-washed chloroplasts are equally inhibited by the antiserum and the inhibition is also observed in the presence of an inhibitor of photophosphorylation like dicyclo-hexyl carbodiimide and in the presence of the uncoupler carbonylcyanide m-chlorophenyl hydra-zone (CCCP) which means that the inhibitory action is directed towards the electron transport chain. Valinomycin which is supposed to affect the cation permeability of the thylakoid membrane has no influence on the inhibitory action of the antiserum. The same is valid for gramicidin. Methylamine on the other hand can induce a state in the thylakoids in which the antiserum is not effective. If the antibodies are already adsorbed prior to the methylamine addition then the high inhibitory effect by the antiserum remains unchanged upon addition of methylamine.

From the experiments it follows that a component from the vicinity of photosystem II is ac­cessible to antibodies that is, the component is located in the outer surface of the thylakoid mem­ brane. It appears that the inhibitory effect is produced in the course of the light reaction.
Light and Dark Adaptation of Crayfish Visual Cells Depending on Extracellular Calcium Concentration
Authors: Stieve H. , Hanani M.
Published: August 2018

Lowering of extracellular Ca2+-concentration from 14 × 10-3 м to ca. 10-6 м (using 1 mм ethyleneglycol bis β-Laminoethylether) -N,N′-tetraacetic acid (EGTA)) results in weaker light adap­tation by a 2 s light exposure and faster dark adaptation (half time 45 ±1%) of crayfish visual cells.
Untersuchungen zur direkten Markierung von Aminosäuren durch hochenergetische 11C -Atome aus Kernreaktionen / Direct Labeling of Amino Acids by Means of Hot 11C-Atoms
Authors: Gundlach G. , Sattler E.L. , Trampisch W. , Wagenbach U.
Published: August 2018

Recoillabeling of amino acids can be accomplished in good radiochemical yield in solid state only. Labeling in solution or in mixture with charcoal or silicagel results in formation of a variety of different products.
Transduction of Turgor Pressure by Cell Membrane Compression
Authors: Coster H.G.L. , Zimmermann U.
Published: August 2018

It is suggested that turgor pressure sensing in plant cells occurs via compression of the cell membranes; either at the plasmalemma where a pressure gradient exists, or the tonoplast due to the pressure developed inside the cell. Considerations of electro-mechanical forces in electrical breakdown of cells suggests that significant changes in the thickness of some regions of the membrane can indeed occur. It is readily envisaged how such changes in membrane thickness can be coupled to changes in active transport processes.
Nucleoside Triphosphate Levels in Streptomyces hydrogenans during Growth and Induction of 20β-Hydroxysteroid Dehydrogenase
Authors: Betz Joachim , Träger Lothar
Published: August 2018

Levels of the purine nucleoside triphosphates are de­ creasing towards the end of log phase growth of Streptomyces hydrogenans. Induction of 20β-hydroxysteroid dehy-drogenase by addition of 11β,21-dihydroxy-4,17 (20) -pregna-dien-3-one to the growth medium leads to a pronounced drop in purine nucleoside triphosphate levels with is irreversible in contrast to the initial loss and later accumulation of RNA.
Induced Isoflavonoids from Fungus-Infected Stems of Pigeon Pea ( Cajanus cajan)
Authors: Ingham John L.
Published: August 2018

Four antifungal isoflavones [7-hydroxy-4′-methoxy-(l) ; 5,7,4′-trihydroxy-(2) ; 5,7,2′,4′-tetra-hydroxy-(3) ; 5,2′,4′-trihydroxy-7-methoxy-(4) ] and one isoflavanone [ (5,2′-dihydroxy-7,4′-dimeth-oxy-(7)] have been isolated from the fungus-infected stems of Cajanus cajan . A sixth compound has been provisionally identified as 5,2′-dihydroxy-7,4′-dimethoxyisoflavone (5). The structure of 5,2′-dihydroxy-7,4′-dimethoxyisoflavanone (cajanol) was confirmed by synthesis from ferreirin ( 5,7,2′-trihydroxy 4′-methoxyisoflavanone).
The Crystal Structure of the Pyrimidine Analogue Calcium 5-Ethylidenehydroorotate · 1.5 Hydrate, a Photoproduct of Ethylorotate
Authors: Hingerty B , Kulikowska E , Saenger W , Shugar D
Published: August 2018

X-ray diffraction methods have been employed to establish the crystal structure of a new, unusual pyrimidine analogue, 5-ethylidenehydroorotate, obtained by a photochemical rearrangement of 5-ethylorotate. Crystals of the calcium salt of the title compound are monoclinic, space group Pc, cell constants a=14.631, 6 = 10.038, c = 19.168 Å,β = 137.7°, and contain four molecules, two cations and three water molecules per asymmetric unit. The structure was solved by direct methods and refined to R = 5.2% on the basis of 2653 diffractometer measured data. The four independent molecules represent two pairs of enantiomers with slightly differing conformations linked together by an intricate system of hydrogen bonding and Ca2+-coordination (pentagonal bipyrimidal). The structure of the compound in aqueous medium, as that in the crystal.
Präparative Isolierung des Protein III der menschlichen Erythrocytenmembran / Preparative Isolation of Protein III of the Human Erythrocyte Membrane
Authors: Schiechl H.
Published: August 2018

The paper describes a method for the large-scale isolation of protein III (protein E, major intrinsic protein) from the human erythrocyte membrane with little expenditure of time. By treat­ment of the erythrocyte ghosts with deluted HCl at pH 2.3 and 0 °C some membrane proteins can be extracted. From the remaining “rest”- membranes, whose major constituents, besides phospholipides, are protein PAS-1, other carbohydrate containing proteins and protein III, the latter can be separated in pure form by means of gel filtration. The paper reports on the amount, purity and possible structural modifications of the protein III obtained by this isolation method.
Effects of Phospholipids in the Action of Acetyl-CoA Carboxylase from Rat Liver
Authors: Heger H. Wolfgang , Peter Horst W.
Published: August 2018

Acetyl-CoA carboxylase (E.C. 6.4.1.2) was isolated from rat liver. The purified enzyme contains phospholipids with a rather large amount of phosphatidylinositol (26%). Incubation of the purified acetyl-CoA carboxylase with phospholipase A2 (E.C. 3.1.1.4) or with phospholipase D (E.C. 3.1.1.4) diminishes the phospholipid content by 70%, this treatment leading to a complete inactivation of the enzyme. After removal of the phospholipases, the lipid-depleted enzyme can be reactivated to a certain degree by incubation with a phospholipid extract from rat liver, with phosphatidylinositol alone, or with serum albumin.
Notizen: Nanoencapsulated Fluorescence Indicator Molecules Measuring pH and pO2 Down to Submicroscopical Regions on the Basis of the Optode-Principle
Authors: Liibbers D. W. , Opitz N. , Speiser P. P. , Bisson H. J.
Published: August 2018

To measure pO2 in gases or fluids and pH in solutions the fluorescence indicators pyrene butyric acid and β-methylumbelliferone, respectively, were nanoencapsulated to obtain nano-probes for measurement in physiological struc­tures of nano-range. For pH the fluorescence changes of β-methylumbelliferone were monitored, for pO2 the fluorescence quenching of pyrene butyric acid by oxygen were registered. Drawing log(S1/S2) versus pH, one obtains a straight line between the pH from 6 to 8. A linear increase in pO2 between O and 400 torr yields a linear increase in the reciprocal fluorescence signal.
Notizen: Prophage Induction by Alkylating Ethyl Methylaminosulfonate
Authors: Burger Klaus , Süßmuth Roland
Published: August 2018

Treatment of the lysogenic strain M. lysodeikticus 53-40 (N5) with ethyl methylaminosulfonate results in a slight increase in infective center concentration of N5 phages which is only detectable once disturbing cells had been eliminated by lysozyme. After conversion of ethyl methylaminosulfonate with radioactive labelled guanosine at 37 °C, N7-ethyl-guanine could be ascertained. Therefore the biological activity of the drug may be due to an ethylation of DNA.
Anomalous Base-Stacking of the N1-Oxide of AMP
Authors: Mantsch H. H. , Bârzu O.
Published: August 2018

The intermolecular association in aqueous solution of the N1-oxide nucleotide analog of adenosine-5′-monophosphate has been investigated by 1H-NMR spectroscopy over the concentration range 0.0006-0.6 ᴍ. The concentration profile of individual chemical shifts provides evidence for an unusual stacking pattern compared to that of the natural nucleotide AMP, involving only the imidazole moiety of the adenine base. The different stacking pattern of this nucleotide analog suggests that the exact stacking geometry of natural nucleotides interacting with nucleotide-depending enzymes, is achieved by adjusting to the geometry of the individual receptor molecule.
The Quaternary Structure of Yeast Aminopeptidase I
Authors: Metz G. , Marx Ruth , Rohm K.-H.
Published: August 2018

The smallest active form of aminopeptidase I (EC 3.4.11.1) from yeast has a molecular weight of 6.4 × 105. At neutral pH the active enzyme is in equilibrium with two inactive subfragments (Mr = 3.2 × 105 and 1.1 × 105) as well as with higher aggregates (Mr ≧ 1.2 × 106). All of these species may be dissociated to give a single type of subunits with a molecular weight of 5.3 × 104. It is concluded that the active enzyme is a dodecamer whereas the subfragments correspond to dimeric and hexameric forms.
A Chloroplast Photosystem 2 Reaction Resistant to Salicylaldoxime
Authors: Searle G. F. W.
Published: August 2018

Photoreduction of the artificial electron acceptor, cytochrome c, by isolated spinach chloroplasts in the absence of added catalyst has been found to be resistant to inhibition by 10 mᴍ salicyl­ aldoxime. This contrasts with the pronounced inhibition of the photoreduction of both 2,6-dichloro-phenolindophenol and ferricyanide over a range of electron flow rates, and indicates an inhibition on the acceptor side rather than on the donor side of photosystem 2 (PS2). All photoreductions were susceptible to inhibition by 3-(3′,4′-dichlorophenyl)-1, 1-dimethyl urea (DCMU). Salicyl­ aldoxime (1 -10 mᴍ) inhibited electron flow from PS2 to P700, and also altered the chlorophyll fluorescence induction of dark-adapted chloroplasts. Salicylaldoxime concentrations up to 5 mM did not change the initial fluorescence level, F0 , or the initial slope, (dF/dt)0 , but lowered the final steady state fluorescence level, Fm , and the value of p0 [p0= (Fm - F0)/Fm] ; an effect similar to that seen on 1 mᴍ ferricyanide addition, thus indicating an induced oxidation of the fluorescence quencher, Q. Both DCMU and orthophenanthroline, which block electron transport directly after Q, caused an increase in (dF/dt)0 , F0 and Fm but left p0 unchanged. This contrasted with the effect of salicylaldoxime.

It is proposed that salicylaldoxime inhibits electron transport from PS2 to photosystem 1, at a site which can probably be identified with the plastoquinone pool, by inducing a cyclic flow of electrons around PS2. Cytochrome c, under the conditions used, appears to be photoreduced at a site close to the secondary electron acceptor, R, of PS2.
Protein Synthesis and Amino Acid Pools in Irradiated Yeast Cells
Authors: Kiefer Jürgen , Laske Brigitte
Published: August 2018

Protein synthesis after UV-and X-irradiation was investigated in diploid yeast. The incorporation of radioactively labelled lysine and phenylalanine was measured 2.5 and 4 hours after exposure. By varying the specific activity the pool sizes could be estimated. At 2.5 hours there is some increase in pool sizes and a dose-dependent enhancement of protein synthesis. At 4 hours pools are again normal, but the increase of synthetic activity prevails.
Flavonoids and Related Compounds in Leaves of Pinaceae. II *. Cedrus atlantica c. v. Glauca
Authors: Niemann Gerard J.
Published: August 2018

Ten flavonol glycosides were isolated from leaves of Cedrus atlantica. Among the six aglycones the rarely occurring syringetin and laricitrin were found in addition to kaempferol, quercetin, isorhamnetin and myricetin. 3-Glyco-sylation with glucose and/or rutinose was the main pattern, whereas acylation with p-coumaric acid occurred for kaempferol-and isorhamnetin-3-glucoside.
γ-Radiolyses of DNA in Oxygenated Aqueous Solution. Structure of an Alkali-Labile Site
Authors: Dizdaroglu Miral , Schulte-Frohlinde Dietrich , Sonntag Clemens von
Published: August 2018

Erythritol-1-d1 has been isolated from γ-irradiated aqueous oxygenated solution of DNA after reduction with NaBD4 , alkali and phosphatase treatment. It is concluded that this product stems from a ᴅ-erythrose 2,4-diphosphate unit in the DNA which is formed via a sequence of reactions following H-abstraction at C-2′ by OH radicals..
Eine vereinfachte Methode zur Ableitung von Rezeptorpotentialen und Nervenim pulsen epidermaler Mechanorezeptoren von Insekten / A Simplified Method for Recording Receptorpoten- tials and Nervous Impulses of Insect Epidermal Mechanoreceptors
Authors: Erler Gernot , Thurm Ulrich
Published: August 2018

A simplified method is described for recording electrical potentials without injury from epidermal insect mechanoreceptors. For this purpose a stationary capillary-electrode is used with an anterior part made of polyethylene and filled with a hygroscopic electrolyte; its wide orifice allows the hair-shaft to keep contact when it is bent under the stimulus.
The Effect of Molecular Polarization on the Electrochromism of Carotenoids * II. Lutein-Chlorophyll Complexes: The Origin of the Field-Indicating Absorption-Change at 520 nm in the Membranes of Photosynthesis
Authors: Sewe Kai-Udo , Reich Roland
Published: August 2018

Electrochromic spectra of monolayers of carotenoids (lutein and β-carotene) in contact with monolayers of chlorophylls and of pheophytin a are measured in thin capacitors. A specific inter­ action of one of the OH-groups of lutein with the Mg-atom of chlorophyll is found. The formation of this oriented complex accounts for the fact that a part of the electrochromic absorption-change of lutein depends linearly on the electric field strength, whereas for lutein alone only a smaller, quadratic electrochromism is found. In the preparation with chlorophyll a, the maximum of this linear electrochromism is located at shorter wavelengths (512 nm) than in the preparation with chlorophyll b (517 nm).

The permanent field that has been postulated in photosynthetic membranes (to explain the linear dependence of the field-indicating absorption-changes of the carotenoids) may also be at­ tributed to such a complex formation with chlorophylls. Especially, the field-indicating absorption-change at 520 nm can now be attributed mainly to a lutein-chlorophyll b complex. The absorption-change at 520 nm, calculated according to this model from the present experiments in vitro, is of the same order of magnitude as observed in vivo. Furthermore, this model agrees with the hitherto unexplained observation that in chlorophyll-b-lacking mutants the absorption-change at 520 nm is smaller than in normal plants, and the maximum is located at shorter wavelengths. Besites, it is concluded that lutein is mainly located in the regions of photosystem II. The contributions of the other carotenoids (especially of neoxanthin) to the spectrum of the field-indicating absorption-changes are also discussed.

From the above model, some conclusions are drawn on the asymmetrical arrangement of the different pigments in the membrane of photosynthesis: The bulk chlorophyll molecules that serve as complex partners for the carotenoids should be located near to the inner surface of the thylakoid membrane, and the carotenoids attached to these chlorophylls should be located more to the out­ side. The phytol chain of a chlorophyll molecule should form an acute angle with the plane of the porphyrin ring.
Photosynthetic Hydrogen Evolution by Spinach Chloroplasts Coupled to a Clostridium Hydrogenase
Authors: Hoffmann D. , Thauer R. , Trebst A.
Published: August 2018

Photosystem I activity of isolated chloroplasts has been coupled to photosynthetic hydrogen evolution via methylviologen and a Clostridium hydrogenase. Rates of 125 μmol hydrogen evolved per mg chlorophyll and hour have been obtained. The conditions for such optimal activity suggest that a closed thylakoid vesicle is required in order to prevent side-and backreactions of reduced methylviologen, which compete with and reduce hydrogen evolution.
The Separation of High and Low Molecular Weight RNA by Precipitation with N-Cetyl- N,N,N-trimethyl-ammoniumbromide
Authors: Seibert Gerhard , Schöbel Barbara , Zahn Rudolf K.
Published: August 2018

RNA with a sedimentation constant of 28S and 18S can easily be separated from 4S and 5S RNA.

The method depends on the different solubulities of nucleic acids in solutions of the cationic detergent N-cetyl-N,N,N-trimethyl-ammoniumbromide at various ionic strengths. The separation can be achieved with high efficiency in one step.
Oscillatory Nervous Response and Transient Vibration (Ear of Locusta migratoria Acrididae, Insecta)
Authors: Adam L.-J. , Dahmen H. , Fastrich P.
Published: August 2018

The summed action potential (SAP) of the receptor axons in the tympanic nerve is a very regular, often nearly harmonic oscillation around an average level. The oscillation amplitude depends on the slope of the stimulus ramp, whereas the average level of the response is determined by the plateau of the ramp. Earlier hypotheses upon the tympanic SAP do not explain the above findings. Yet the transient solutions of a simple oscillator model reproduce the tympanic oscillations.
Benzo(a)pyrene Metabolites Formed by Plant Cells
Authors: Harms Hans , Dehnen Walter , Mönch Wolfgang
Published: August 2018

Benzo (a) pyrene, added to the nutrient solutions of cell suspension cultures of Chenopodium rubrum, was metabolized to oxygenated derivatives. With increasing time of incubation decreasing amounts of the added 14C-radioactivity could be extracted with 70% methanol or be isolated as benzo (a) pyrene. The amount of metabolites formed increased with increasing time of incubation. After 48 hours most of the radioactivity was found in the extracted residue. These observations and some other indications give reason to believe that some of the metabolites are linked to proteins or nucleic acids.
Metabolites of β, β-Carotene in the Stick Insect, C arausius morosus Br.: Compounds with 2-One and 3,4-Didehydro-2-one Structure
Authors: Kayser Hartmut
Published: August 2018

Six novel keto carotenoids have been isolated from the stick insect. The structure of the pre­dominant red pigment has been assigned to 3,4,3′,4′-tetradehydro-β,β-carotene-2,2′-dione on the basis of electronic, infrared, and mass spectra. Minor pigments are 3,4-didehydro-β,β-carotene-2,2′-dione, 2′-hydroxy-3,4-didehydro-β,β-caroten-2-one, and 2′-hydroxy-β,β-caroten-2-one. Two other com­pounds, β,β-caroten-2-one and β,β carotene-2,2′-dione, have been tentatively identified. The ad­ ditional occurrence of β,β-caroten-2-ol and β,β-carotene-2,2′-diol has been reported recently. All hydroxylated pigments are mainly present as fatty-acid esters. During hydride reduction of the 3,4-didehydro-2-one compounds hydrogenation of the 3,4-double bond was observed as a side reaction.

A hypothetical scheme of carotenoid metabolism in the stick insect is proposed. According to this pathway the keto groups are introduced by a pseudo one-step reaction; the hydroxylated pig­ments are thought to be reduction products of the corresponding ketones. The proposed pathway is fitting more to physiological data than an alternative one based on the hydroxyl →carbonyl sequence.
Molecular Weight and the Dodecyl Sulphate Binding of a Thylakoid Membrane Polypeptide Involved in a Reaction on the Oxygen-Evolving Side of Photosystem II
Authors: Craubner Hans , Koenig Friederike
Published: August 2018

The molecular weight of a thylakoid membrane polypeptide with the apparent molecular weight 11 000 was determined by measurement of the sedimentation velocity, the diffusion and the ef­fective partial specific volume. The molecular weight was found to be 6300 and that of the poly-peptide-dodecyl sulphate micelle was found to be 11 200. The frictional ratio was 1.35. In ad­dition, we determined the binding of dodecyl sulphate onto the polypeptide by equilibrium dialysis. We found that 1 g polypeptide binds 0.77 g sodium dodecyl sulphate which corresponds to 17 molecules dodecyl sulphate bound per polypeptide chain. In the absence of dodecyl sulphate the polypeptide aggregates. The molecular weights of the aggregates are in 0.01 м sodium phosphate buffer pH 7.2 150 000 and in a 1 :1 mixture of 0.01 м phosphate buffer and 96% ethanol 365 000. The frictional ratios were 1.07 and 1.16 respectively which points at a spherical shape.

The experimental conditions for the determination of the dodecyl sulphate binding were critically scrutinised.
Isolation of Messenger Ribonucleoproteins from HeLa Cells by Affinity Chromatography on Poly (U) Sepharose
Authors: Liautard Jean-Pierre , Tromm Dagmar , Köhler Kurt
Published: August 2018

Polysomes of HeLa cells were adsorbed on Poly (U)-Sepharose columns. This adsorption is probably due to poly (A) sequences at 3′ terminus of the messenger. Stepwise elution initially removed ribosomal subunits thereafter mRNA and a set of proteins.

These proteins are identical with the main components of the polysomal messenger ribonucleo-protein particles described previously. Thus, this method allows their rapid and easy separation from ribosomal and other proteins.
Notizen:Untersuchungen über Carotinoide in Gametangien und Sporen von Allomyces arbuscula/ Studies on Carotenoids in Gametangia and Spores of Allomyces arbuscula
Authors: Fähnrich P. , Chenaux L.
Published: August 2018

Carotenoids were extracted from gametophytes of Allomyces arbuscula at different periods during gametogenesis. After separation by thin-layer chromatography γ-carotene, lycopene and β-carotene were identified from their absorp­tion spectra in visible light. No other carotenoids were detected. After a lag period of 30 min following induction of gametogenesis γ-carotene was the only carotenoid present in extracts, followed by traces of β-carotene at 60 min and by lycopene at 90 min. Accumulation of carotenoids continued during the later stages of gametangia development. Analysis of pigments that had been extracted from asexual mitospores showed that these spores contained both γ-carotene and lycopene.
Notizen: Medicarpin as a Phytoalexin of the Genus Melilotus
Authors: Ingham John L.
Published: August 2018

The phytoalexin medicarpin has been isolated from the fungus-inoculated leaves of 19 Melilotus species.
Binding of Copper(II) to Proteins of the Photosynthetic Membrane and its Correlation with Inhibition of Electron Transport in Class II Chloroplasts of Spinach
Authors: Vierke Gerhard , Struckmeier Peter
Published: August 2018

Incubation of class II chloroplasts of spinach with copper in the light at pH = 8 in concentrations that inhibit oxygen evolution results in the formation of a copper (II) protein complex with the photosynthetic membrane. The EPR spectra indicate that the four nearest ligands to Cu(II) consist of three oxygen atoms and one nitrogen atom. The copper (II) protein appears to be pre­ dominantly associated with photosystem II. The formation of this protein as measured by the EPR signal amplitude of its room temperature spectrum correlates with the inhibition of oxygen evolution and of electron transport within photosystem I. This result indicates that the inhibition of photosynthetic electron transport by copper may be due to the formation of a copper (II) chelate with a membrane protein.
A Comparative Study of the Endocrine System of the Honey Bee Larvae under Normal and Experimental Conditions
Authors: Dogra G. S. , Ulrich G. M. , Rembold H.
Published: August 2018

The endocrine system of the honey bee (Apis mellifera L.) has been studied morphologically through post-embryonic development with several histological techniques. Marked differences in the structure of the neurosecretory complex of queen and worker larvae have been observed during larval stages. In queen larvae, morphogenesis of the neurosecretory cells, their axons and the formation of the chiasma takes place during end of 2nd and beginning of 3rd, in the workers at beginning of 4th larval instar. Stainable neurosecretory material was found in queen larvae at the beginning, in worker larvae at the end of 4th instar. In early larval stages, the corpora allata are more active in the queen. During initial 3 - 5 days of larval development the gland volume is reduced in both castes. After 36 to 48 hours of endocrine retardation, the glands become active again. The same histological effects are found under experimental conditions, where worker larvae of 2nd instar were reared in the incubator on basic food, Royal Jelly and with topically applied juvenile hormone I.
The Adenine and Thymine Molecules. Some Excited Singlet and Triplet Levels of the Normal and Tautomeric Forms
Authors: Marañon Julio , Sorarrain Oscar M.
Published: August 2018

The shape of the barrier for the H transfer between the normal and tautomeric forms have been determined for the adenine and thymine molecules. The correlations for several singlet and triplet states has been calculated using the CNDO/2-Cl method. The relative stability between both conformations and the agreement with some experimental values is also discussed.
Microvillar Orientation in the Retina of a Pierid Butterfly
Authors: Maida Tom M.
Published: August 2018

The orientation of microvilli in the compound eye of the butterfly. Pieris protodice, has been examined using electron microscopy. The retinula cells comprising each ommatidium have been divided into four types based upon microvillar orientation, position of nucleus, and location within the om­matidium. The vertical and horizontal retinular types have microvilli in the distal one-third to half of the retina. There is alteration in the orientation of these microvilli of up to 90 . The rhabdom is dominated by the microvilli of the diagonal retinulae in the proximal retina. There is consistant orientation of the diagonal cell microvilli throughout the retina. In mid-retina, these microvilli undergo dramatic alteration in length, leading to a Crustacean-like organiza­tion. for some 50 μm. The basal, or eccentric, retinula cell is bilobed. and has only a few microvilli projecting a short distance into the rhabdom.
Microvillar Orientation in the Retina of the Nymphalid Butterfly
Authors: Gordon William C.
Published: August 2018

The photoreceptor cells of the nymphalid butterfly, Agraulis vanillae, have been structurally characterized. Four distinct types of retinulae can be found in each ommatidium.Two vertically oriented cells contribute microvilli to the to rhabdom only in the distal retina. These microvilli are or-ha]dered into discrete packets. Although the distal-most micro­villi enter the rhabdom in a dorsal-ventral axis, these rhabdomeral packets begin altering their direction of orientation becoming directed at 45° to the vertical alignment of the cells. Abrupt alternations in orientation produce microvillar packets oriented to each other at approximately 90° along the distal portion of each vertical cell. The vertical reti­nulae lose their microvilli at mid-retina and become axonal.Four retinular cells, oriented diagonally across the ommati­dium, contribute microvilli to the rhabdom aligned at 45° to the vertical axis. These diagonal cells produce microvilli throughout the depth of the retina. Two horizontally ordered photoreceptors produce microvilli aligned along a horizontal axis, these cells contributing rhabdomeres along their entire length. A ninth bilobed eccentric cell is arranged in a vertical plane in the basal region of the ommatidium. A few short microvilli are added to the rhabdom from each lobe.These are oriented in a vertical direction.
Untersuchung der Rekombinationskinetik von photodissoziiertem Myoglobin-CO bei tiefen Temperaturen mittels Mössbauer-Spektroskopie / Investigation of the Recombination Kinetic of Photodissoziated Myoglobin-CO at Low Temperatures by Mössbauer Spectroscopy
Authors: Marcolin H. E. , Reschke R. , Trautwein A.
Published: August 2018

Myoglobin, Mössbauer Spectroscopy, Recombination Kinetic Myoglobin-CO (MbCO) has been photodissoziated with white and monochromatic light at low temperatures (5-40 °K). The photoproduct Mb* was identified with Mössbauer spectroscopy as ferrous high-spin complex, with isomer shift and quadrupole splitting, which are similar to the corresponding parameters of deoxymyoglobin. From the time-dependent change of the linewidth of the Mb*-Mössbauer-spectrum at 5 °K over a time-intervall of 7 hours we conclude, that there exist several slightly different Mb*-conformations with different recombination characteristics. In order to obtain a convenient time resolution of the recombination behavior, we investigate the time-dependence of one of the Mb*-absorptionlines with a Mössbauer drive of constant velocity. The resulting recombination data then are analzyed in various steps of approximation. It is shown that at least two independent exponentials are necessary for the interpretation of experimental data. The attempt to interprete the experimental data on the basis of distribution of energies is in qualitative agreement with corresponding results, which are derived from optical recombination data by Austin et al. Typical activation energies for the recombination process CO → Mb* are 2 kcal/mol. At low temperature (T < 46 °K) the recombination behavior is explained by quantum-mechanical tunneling.