bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of the Membrane Potential on the Intracellular Light Induced Ca2+ -Concentration Change of the Limulus Ventral Photoreceptor Monitored by Arsenazo III under Voltage Clamp Conditions
Authors: Ivens I. , Stieve H. 
Published: August 2018

Abstract
The light induced transmission change (Arsenazo signal) of an Arsenazo III injected ventral photoreceptor cell of Limulus polyphemus was studied under voltage clamp. The transmission change which represents a change of free intracellular calcium ion concentration, [Ca2+]i, was investigated for its dependence upon membrane voltage.
The peak amplitude of the Arsenazo signal decreases in a linear fashion with the clamp voltage in the examined voltage range (from -80 to + 40 mV).
In low Ca2+ saline ([Ca2+]e = 250 μᴍ) this decrease in the amplitude of the Arsenazo signal was more pronounced, while in saline with increased Ca2+ ([Ca2+]e = 40, 50 and 100 mᴍ), there is almost no change of the Arsenazo signal with varied membrane voltage.
The recovery of the Arsenazo signal (i.e. recovery of the transmission back to the value before the light flash) is faster during hyperpolarization, this recovery being slowed down when the cell is depolarized.
From these experiments it is concluded that a substantial part of the Arsenazo signal is due to a light induced influx of Ca2+ from the extracellular space across the cell membrane into the cytoplasma. Conceivably the Ca2+ could pass through light activated Na+ channels. Subsequently the increased intracellular Ca2+ is lowered to the preillumination level, by a membrane voltage dependent mechanism possibly an Na+-Ca2+ exchange.
The data do not exclude the possibility that a part of the Ca2+ responsible for the Arsenazo signal is released from intracellular stores.
Purification and Properties of Adenosine Kinase from Rat Liver: Separation from Deoxyadenosine Kinase Activity
Authors: Drabikowska Alicja K. , Halec Lidia , Shugar David 
Published: August 2018

Ion exchange and affinity chromatography techniques, similar to those previously reported for purification of adenosine kinase from human placenta, were applied to purification of rat liver adenosine kinase. The enzyme, purified 400-fold in 41% yield, was homogeneous on SDS- polyacrylamide gel electrophoresis, with a molecular weight of 52000. It specific activity, 18 μmol/min/mg protein, is the highest hitherto reported for this enzyme from mammalian sources.
Chromatography on DEAE-cellulose removed about 98% of the phosphorylating activity towards 2′-deoxyadenosine present in the initial pH-treated liver extract. The final preparation exhibited only minimal activity (~ 1.5%) under optimal conditions (pH 7.5) vs- 2′-deoxy- adenosine, the lowest yet reported for such a preparation, with a Km of 670 μᴍ, as compared to 0.3 μᴍ for adenosine.
The residual activity towards deoxyadenosine is considered an intrinsic property of the purified adenosine kinase and, in fact, phosphorylation of adenosine was inhibited competitively by deoxyadenosine, with a of 70 μᴍ. Competitive inhibition was also exhibited by cordycepin (3′-deoxyadenosine) with a Ki of 150 μᴍ. A more potent competitive inhibitor was tubercidin, the Ki for which was 1.9 μᴍ.
Production of Four Interfacial Active Rhamnolipids from n-Alkanes or Glycerol by Resting Cells of Pseudomonas species DSM 2874
Authors: Syldatk C. , Lang S. , Matulovic U. , Wagner F. 
Published: August 2018

In a simple phosphate buffer or a sodium chloride solution resting cells of Pseudomonas spec. DSM 2874 produced up to 15 g/l of different rhamnolipids. The rhamnolipid composition of the organic crude extract depended on the temperature during the cultivation and on the C-source. The optimal sodium chloride concentration for rhamnolipid formation was about 100 mᴍ/l and the optimal phosphate buffer concentration about 65 mᴍ/l. The optimal pH-value for the production of rhamnolipids from n-alkanes or glycerol was in the range pH 6.0-7.2. While rhamnolipid formation with glycerol as the sole C-source showed a wide optimum ranging from 27° up to 37 °C, production of rhamnolipids from n-alkanes had a sharp optimum at 37 °C. The addition of multivalent cations, different N-sources and EDTA caused an inhibition of rhamnolipid formation, while the n-alkane concentration had no influence. Specific rhamnolipid formation decreased with increasing cell concentration. Various C-sources were suitable for the formation of rhamnolipids by resting cells of Pseudomonas spec. DSM 2874. Yields, which were comparable to those obtained on n-alkanes or glycerol, were found for stearic acid, fatty alcohols and vegetable oils.
A study of the time course of glycolipid production of resting cells was carried out in a 20 1- biorcactor with an intcnsor system and with n-tetradecane as the sole C-source.
Kinetics of Calcium-Induced Fusion of Cell-Size Liposomes with Monolayers in Solutions of Different Osmolarity
Authors: Stoicheva Natalia , Tsoneva Iana , Dimitrov Dimiter S. , Panaiotov Ivan 
Published: August 2018

The effects of osmolarity, calcium concentration and cell-size liposomes in the subphase on the surface tension of phospholipid monolayers were investigated. The monolayers were spread from chloroform solutions of phosphatidic acid at air/water solution interface. The liposomes (of average diameter 3 μm) were formed from phosphatidic acid/egg lecithin (1:2) mixtures in water or 0.1 ᴍ water solutions of sucrose.
For this system there were critical concentrations of calcium ions to produce a large reduction of the monolayer surface tension. The threshold calcium concentrations depended upon the sucrose concentration in the subphase. Without sucrose the threshold calcium concentration was 8 mᴍ, while for isoosmotic sucrose solutions (0.1/0.1 ᴍ in/out of liposome) it was 14 mᴍ. It sharply increased to 28 mᴍ CaCl2 at sucrose concentration difference across the liposome membrane 0.02 ᴍ and decreased to 26 mᴍ, 19 mᴍ, and 18 mᴍ with further increase of that difference to 0.04 ᴍ, 0.06 ᴍ, and 0.08 ᴍ, respectively.
The rate of monolayer surface tension decrease was measured as a function of time at 30 mᴍ CaCl2 and different sucrose concentrations in the subphase solution. The initial rates at first decreased with increasing the osmotic pressure and after that they increased. The minimum occurred at sucrose concentration gradient across the liposome membrane 0.02 ᴍ, i.e., at the point of maximum threshold calcium concentration required for large decrease of the monolayer surface tension. These facts may be explained by recent theories of dynamics of adhesion, instability and fusion of membranes modeled as thin films.
Male Produced Volatiles from Coreid Bug Leptoglossus australis\ (Heteroptera)
Authors: Gough A. J. E. , Games D. E. , Staddon B. W. 
Published: August 2018

Abstract
From the ventral abdominal gland VII-VIII in male adult Leptoglossus australis, five volatiles have been identified by GC and MS data in comparison with authentic standard materials. Benzyl alcohol (31%) and 2-phenyl ethanol (42%) together accounted for over 70% of the total scent. The remaining materials identified were 2-octenyl propionate (19%), (E,E′)-2,4-hexadienyl acetate (6%) and (E)-2-hexenol (2%).
Studies on the Triple Helical Structure of β-ᴅ-1,3 Xylan
Authors: Haleem M. A. , Qamruddin Salma 
Published: August 2018

Abstract
The triple helical structure of β-ᴅ-1,3 xylan is described. The 0-value is reduced to 3.447 from 4.417 by number of small modifications to the structure including variations in the position of water molecule. The R-value after the refinement is found to be 0.37. The present calculations indicate that water is certainly involved with the structure possibly in a more complicated way as proposed by earlier workers. The present work supports the previous finding of Haleem and Parker that the molecule should be 8% smaller in radius.
The Role of N ADPH in the Reversible Phototransformation of Chlorophyllide P682 into Chlorophyllide P678 in Etioplasts of Oat
Authors: Franck Fabrice , Schmid Georg H. 
Published: August 2018

Abstract
Absorption spectra and room temperature fluorescence variations upon light excitation were studied in etioplasts in which the protochlorophyllide had been reduced to chlorophyllide prior to the experiment. In the presence of 1 mᴍ NADPH, the absorption band was located around 682 nm and the fluorescence variations reflected the occurrence of the chlorophyllide microcycle (reversible phototransformation of chlorophyllide P682 into chlorophyllide P678), whereas, in the absence of NADPH, the absorption band was located around 676 nm and the fluorescence exhibited only a slow decrease with illumination time. After washing, NADPH-treated etioplasts still exhibited an absorption maximum of 682 nm, which shifted irreversibly to 678 nm upon illumination. Re-addition of only 10 μᴍ NADPH restored the reversibility of the reaction. Plastids were also prepared after a brief illumination of the intact leaves. These plastids contained the P682 chlorophyllide. In this preparation, essentially the same phenomena were observed as in NADPH-treated etioplasts after washing. Moreover, enzymic oxidation of NADPH resulted in the transformation of P682 into P678 in darkness. Addition of the Hill electron acceptors 2,6- dimethylbenzoquinone on FeCN caused an acceleration of the phototransformation of P682 into P678. We interpret these results as being due to the oxidation of NADPH during the phototransformation of P682 into P678. The nature of the electron acceptor and the physiological role of this reaction is discussed.
Reculturing of Cells from Primary CFU-C Colonies
Authors: Hübner G. E. , Ali-Osman F. , Kästner M. , Papadimitriou C. , Maurer H. R. 
Published: August 2018

Abstract
This study was aimed at investigating whether cells of CFU-C derived colonies could form secondary colonies. Bone marrow cultures of volumes of agar medium between 25 μl and 75 μl contained in glass capillaries were stimulated with mouse lung-conditioned medium (MLCM) containing granulocyte/macrophage colony-stimulating factor (GM-CSF). Agar gels with colonies of up to ≥ 20 were blown out into identical culture medium, completely dispersed on a whirl-mix to single cell suspensions, and used for establishing secondary agar cultures. In these secondary cultures considerable numbers of secondary granulocytic, mixed granulocytic/macrophage and macrophage colonies as well as numerous clusters arose. In contrast, when single colonies were recultured, only few secondary cell aggregates were formed. When primary cultures containing up to ≥ 20 cell aggregates were used for serial reculture at intermittent intervals of 3 and 4 days, a 2 -7-fold increase of colony-forming cells was found in tertiary cultures as was monitored by 7 day colony counts. And by use of different kinds of CSF-containing media, an over 4-fold increase of secondary over primary colonies was obtained with bovine lung-conditioned medium (BLCM) in primary and L-cell-conditioned medium (LCCM) in secondary 7 day cultures. Primary capillary cultures were found to be devoid of CFU-S. Also, setting up bone marrow cultures in petri dishes and stimulating with MLCM, growth of primary as well as secondary colonies was obtained. The results indicate some self-renewal potential of CFU-C in vitro.
Säugetierspermatogenese als biologischer Indikator für ionisierende Strahlung / Mammalian Spermatogenesis as a Biological Indicator for Ionizing Radiation
Authors: Hacker-Klom Ursula , Meier Eva-Maria , Göhde Wolfgang 
Published: August 2018

Abstract
We have analysed spermatogenetic cells by flow cytometry to quantify effects of ionizing radiation. The radiation-induced reductions of testicular DNA-synthesizing cells, primary spermatocytes, haploid round and elongated spermatids as well as the increases of numerical chromo­ some aberrations (abnormal diploid spermatids and aneuploidies) in NMRI inbred mice are described. Testicular weights were determined as a parameter of germ cell decrease, and histologic cross sections of the testes were analysed. Since even an exposure of 0.05 Gy (= 5 rad) may be detected by a reduction of DNA-synthesizing cells (Acta Radiol. Oncol. Radiat. Phys. Biol. 21, 349-351 (1982) [1]), the use of the in vivo system “spermatogenesis” as a biological dosimeter to monitor low dose effects and to determine RBE values of different radiation qual­ ities is suggested.
Analytical Ultracentrifugation of Proteins in Solutions of Triton X-100 Using Absorption Optics
Authors: Schubert Dieter , Boss Karin 
Published: August 2018

Abstract
Analytical ultracentrifugation studies on proteins in solutions of the nonionic detergent Triton X-100, by means of a UV scanning system, can be conveniently performed by the following procedure: (1) Scanning of the cells is done at a wavelength of 246 nm. (2) The sedimentation of the deter­ gent is prevented by appropriate adjustment of the solvent density. (3) The reference cell is filled with water. Reliable molecular weight determinations can be performed at detergent concentrations up to 0.4% (w/w) in cells of path-length d = 12 mm and at correspondingly higher concentrations for d - 3 mm. Approx. 10 μg of protein are sufficient for a determination. The method should be useful for studies of membrane proteins.
ʟ-Tyrosine as a Precursor of Flavonoids in Buckwheat Cotyledons
Authors: Margna U. , Laanest L. , Margna E. , Vainjärv T. 
Published: August 2018

Abstract
Exogenous ʟ-tyrosine was incorporated 13 -14 times less effectively than exogenous L-phenylalanine into flavonoids in excised cotyledons of 3 days old buckwheat seedlings but proved to be an only 5 times poorer precursor when the experiments were carried out with 5 days old material. Simultaneous administration of ʟ-phenylalanine markedly reduced incorporation of ʟ-tyrosine into flavonoids. A similar decrease in the utilization of exogenous ʟ-tyrosine for flavonoid bio­ synthesis occurred in kinetin-treated cotyledons. However, in cotyledons treated with high doses of glyphosate, an inhibitor of the shikimic acid pathway, an increase in the formation of flavonoids from exogenously supplied ʟ-tyrosine was observed. Under all conditions the relative incorporation rate of exogenous L-tyrosine was highest for anthocyanins and lowest for C-glycosylflavones while within the latter class of compounds the luteolinic derivatives orientin and isoorientin incorporated more label than their apigeninic analogues vitexin and isovitexin. PAL and TAL activities were found to be present in the cotyledons in a ratio of 50:1. The possible role of ʟ-tyrosine as an alternative natural precursor for the biosynthesis of flavonoids and other related polyphenols is discussed.
Differential Inhibition by Mevinolin of Prenyllipid Accumulation in Radish Seedlings
Authors: Schindler Sibille , Bach Thomas J. , Lichtenthaler Hartmut K. 
Published: August 2018

We have studied in intact radish seedlings the effects of mevinolin (at concentrations of 0.25 to 5 μᴍ), a specific inhibitor of HMG-CoA reductase, and, therefore, of mevalonate biosynthesis, on the production of various isopentenoids and prenyllipids. Whereas the content of free desmethyl sterols was decreased steadily, only depending on the concentration of inhibitor present in the parts of seedlings investigated separately (e.g. roots, hypocotyls. and cotyledons), the effect on ubiquinone accumulation was different. Irrespective of the part of seedlings being analyzed, the maximal inhibition reached was 50%. Plastidic pigment accumulation, however, as well as that of chloroplast quinones (plastoquinone and phylloquinone), appeared even to be enhanced at low inhibitor concentrations and was not significantly lowered by application of 5 μᴍ mevinolin. α-Tocopherol showed a similar profile in the dose response to compounds known to be exclusively synthesized in the plastid.
The results indicate a differential accessibility of the mevalonate synthesizing enzymes presumably present in the cytoplasm, mitochondria and plastids in respect to the inhibitory action of mevinolin. If prenyllipid formation in the different cell compartments solely depended on cytoplasmic mevalonate biosynthesis, all prenyllipids should be affected to the same extent as the sterols, which are exclusively synthesized by cytoplasmic enzymes.
Adsorbent Filter — A Tool for the Selection of Plant Suspension Culture Cells Producing Secondary Substances
Authors: Knoop Bernd , Beiderbeck Rolf 
Published: August 2018

Abstract
Cells and cell aggregates from suspension cultures are plated onto selection plates, consisting of:
1. A layer of nutrient medium solidified with agar
2. A filter paper coated on the upper side with activated charcoal (AC) as an adsorbent
3. covered by a sheet of cellophane as cell carrier.
Substances produced migrate through the cellophane and are locally bound to the adsorbent layer. A fter transfer of the cells together with the cellophane to another dish the adsorbent filter is dried and the substances bound to the AC are eluted to the white side of the filter paper where they can be detected by m eans of standard methods of TLC and PC.
The substance pattern mirrors the pattern of cell material and allows to discover those cells with deviating substance production.
This method is used to recover cell aggregates of Nicotiana tabacum and Matricaria chamomilla from a mixture of both cultures.
The Influence of Low-intensity Millimeter-Wave Radiation on the Growth of Cress Roots
Authors: Kremer F. , Poglitsch A. , Santo L. , Sperber D. , Genzel L. 
Published: August 2018

Abstract
An inhibition of growth in cress roots (Lepidium sativum L.) by irradiation with low-intensity millimeter-waves was found using a computer controlled optical system which is capable of measuring nearly continuously the length of the roots to an accuracy of ± 2 jam. The effect is reversible and, for a power density of 6 mWcm-2, results in completely halting the root growth. It occurs within about 100 s after the onset of irradiation. The microwave-induced temperature increase at the surface of the root tip was found to be less than 0.3 °C at this power density. The effect did not show a sharp frequency dependence however it depended strongly on the polariza­tion of the microwaves with respect to the root orientation.
The sensitivity of the root growth to the ambient temperature was examined. Only a weak temperature dependence was found which could not explain the observed effects. However simulating the microwave-induced temperature increase at the surface of the root tip with (incoherent) far-infrared light (λ≥20 μm) resulted in similar effects as with microwaves. Hence one can conclude that the observed effects are primarily caused by the small local irradiation induced thermal gradients across the surface of the root tip.
A Small-Angle X-Ray Scattering Study on Pre-Irradiated Malate Synthase. The Influence of Formate, Superoxide Dismutase, and Catalase on the X-Ray Induced Aggregation of the Enzyme
Authors: Zipper P. , Wilfing R. , Kriechbaum M. , Durchschlag H. 
Published: August 2018

Abstract
The sulfhydryl enzyme malate synthase from baker’s yeast was X-irradiated with 6 kGy in air-saturated aqueous solution (enzyme concentration: ≃ 10 mg/ml; volume: 120 μl), in the absence or presence of the specific scavengers formate, superoxide dismutase, and catalase. After X-irradiation, a small aliquot of the irradiated solutions was tested for enzymic activity while the main portion was investigated by means of small-angle X-ray scattering. Additionally, an unir­radiated sample without additives was investigated as a reference. Experiments yielded the fol­lowing results:
1. X-irradiation in the absence of the mentioned scavengers caused considerable aggregation, fragmentation, and inactivation of the enzyme. The dose Dt
37 for total (= repairable + non­-repayable) inactivation resulted as 4.4 kGy. The mean radius of gyration was found to be about 13 nm. The mean degree of aggregation was obtained as 5.7, without correction for fragmenta­tion. An estimation based on the thickness factor revealed that about 19% of material might be strongly fragmented. When this amount of fragments was accordingly taken into account, a value of 7.1 was obtained as an upper limit for the mean degree of aggregation. The observed retention of the thickness factor and the finding of two different cross-section factors are in full accord with the two-dimensional aggregation model established previously (Zipper and Durchschlag, Radiat. Environ. Biophys. 18, 99 - 121 (1980)).
2. The presence of catalytic amounts of superoxide dismutase and/or catalase, in the absence of formate, during X-irradiation reduced both aggregation and inactivation significantly.
3. The presence of formate (10 or 100 mᴍ) during X-irradiation led to a strong decrease of aggregation and inactivation. This effect was more pronounced with the higher formate concen­tration or when superoxide dismutase and/or catalase were simultaneously present during X-irradiation. The presence of formate also reduced the amount of fragments significantly.
4. The results clearly show that the aggregation and inactivation of malate synthase upon X-irradiation in aqueous solution are mainly caused by OH·; to a minor extent O·̄
2 and H2O2 are additionally involved in the damaging processes.
Physiology of Nitrogen Fixation in Two New Strains of Anabaena
Authors: Chen Pei-Chung 
Published: August 2018

Abstract
Two different cyanobacteria, Anabaena CH 1 and CH2, were isolated from Taiwan paddy soils. Both strains can grow well with daily dilution method. Anabaena CH1 shows a blue-green color and Anabaena CH2 a green brownish one. Nitrogenase activity decreased as cultures were transferred from light to dark. When a darkened culture was placed again into the light, nitrogenase activity recovered within two hours, but not in the presence of chloramphenicol. Energy supply for nitrogenase within both strains was different. Nitrogenase activity of Anabaena CH1 was light-dependent and oxygen in heterocyst was exhausted through oxyhydrogen reaction. Except photosynthesis, respiration may be used as energy source for nitrogenase in Anabaena CH2. Respiration was the major one to protect nitrogenase against oxygen.