Volume 28, Issue 5-6

All possible enantiomers of stereospecifically labelled [1- 2 H] ethanol, propanol and butanol have been prepared on a scale of up to 7 ml. The R forms have been obtained by incubation of the alcohols with alcohol dehydrogenase and diaphorase (NAD: Lipoamide oxidoreductase, EC 1.6.4.3) in presence of catalytic amounts of NAD + /NADH in deuterium oxide. The S forms have been prepared with the same enzymes in ordinary water, from the corresponding [1,1- 2 H] alcohols. (IS) [1- 2 H] ethanol was prepared from [1,1- 2 H] ethanol and ordinary water, by a yeast catalyzed exchange reaction.

The spectral properties of binary complexes of NAD-analogues and fragments therefrom with I.DH from pig heart or ADH from liver and yeast have been investigated. The NADH-analogues were modified by replacing adenine through benzimidazole, benzene or dihydronicotinamide. Additionally adenosine diphosphate ribose, dihydronicotinamide and dihydronicotinamide- ribose pyrophosphate-5"-ribose have been studied. It has been shown by means of difference spectra that complexes between ADH from horse liver and analogues cause spectral changes in the region of aromatic absorption at 280 nm even when adenine is absent in the analogues. Spectral changes in the other enzymes mentioned are probably due to changes of the n-π* absorption of the adenine ring. The spectral changes upon complexing indicate hydrophobic interaction of the adenine with the enzyme protein. Fluorescence spectra vary in the intensity of the energy transfer band as well as in coenzyme emission depending on variation of the coenzym analogue. Changing of complex formation between protein and analogues at different pH-values are investigated. ADH from yeast, especially, shows a pK around 6 which suggests interaction with histidine imidazole.

The structure of the yellow main pigment of Cortinarius vitellinus has been established as 4-hydroxy-flavomannin-6,6′-dimethyl ether A1 (1). 1 is easily oxidized to a number of quinones, whose structures have been elucidated by mass spectrometry. A nomenclature for stereoisomeric flavomannin derivatives is proposed.

A detailed study of the furocoumarins present in the seeds of Citrus trifoliata L. revealed the presence of isopimpinellin, prangenin and prangenin hydrate in addition to the already reported bergapten and imperatorin. The amount of these compounds, referred to the starting dry material, were: Imperatorin 0.15%, bergapten 0.06%, whereas isopimpinellin, prangenin and prangenin hydrate were found in the order of less than 0.01%.

Euglena gracilis was grown in the dark for 12 days in a medium containing sodium acetate- 1- 14 C. The major amount of 14 C was incorporated into the neutral lipids. In these compounds myristic acid was the main fatty acid labeled. Subsequent growth in light (70 hours) in an identical medium (containing unlabeled acetate) led to a strong decrease of radiocarbon in the neutral lipids. The radioactivities in phosphatidyl choline and phosphatidyl ethanolamine increased during the first 28 hours of illumination and thereafter decreased. The radioactivities in phosphatidyl glycerol, sulfolipid, monogalactosyl diglyceride and digalactosyl diglyceride increased continously. After 70 hours of illumination, most of the radiocarbon was detected in the saturated and unsaturated C 16 and C 18 fatty acids of these four lipids. The possibility of light-induced transfers of fatty acids from neutral lipids via phospholipids to the galactolipids is discussed.

Euglena gracilis was grown in the dark for 12 days. Subsequent incubation with sodium octanoate- l- 14 C in the dark for 6 hours resulted in a rather specific incorporation of radioactivity into the neutral lipids (primarily wax esters). Upon illumination of these cells in an identical medium without radiocarbon, the radioactivities in the neutral lipids decreased strongly, due to a decrease of the labeled wax acids (mainly 1 4:0) and wax alcohols (mainly C 14 ). The radioactivities in phosphatidyl choline and phosphatidyl ethanolamine increased during the first 24 hours of illumination and thereafter decreased. This was caused by the initial increase and subsequent decrease of the labeled 14:0 and 16:0 acids in phosphatidyl choline and of the 14:0, 16:0 , and 18:1 acids in phosphatidyl ethanolamine. The chloroplast lipids (sulfolipid, phosphatidyl glycerol, monogalactosyl diglyceride, and digalactosyl diglyceride) exhibited a steady increase in radiocarbon content. This was due to an increase of label in the 16:0 fatty acid of the sulfolipid, in the 16:0 and trans3-16:1 fatty acids of the phosphatidyl glycerol, and in the saturated and unsaturated C 16 and C 18 fatty acids of the monogalactosyl and digalactosyl diglycerides. The labeled fatty acids of the above phospho- and glycolipids had comparably high specific radioactivities. Incorporation of radiocarbon into the last two carbon atoms of their methyl ends, however, was low. The glycerol and sugar moieties of the individual lipids incorporated relatively little radiocarbon. It is concluded that in Euglena gracilis the biosynthesis of long chain fatty acids is associated with specific lipids. Upon illumination, oxidative breakdown of the neutral lipids as well as transfers of fatty acids from the neutral lipids via phosphatidyl choline and phosphatidyl ethanolamine to the chloroplast lipids seem to be induced. The lipids involved appear to function as parts of a “lipid-bridge” for the acyl transfers.

The nitrogen fixing blue-green algae, Anabaena cylindrica and Nostoc muscorum , were grown as 71 cultures in various media, at different temperatures (15 °C and 23 °C ), and under light of different wavelengths. In all cases, the amount of combined nitrogen excreted into the medium readied a value of 700 - 800 μMol N/1 of nutrient medium after 4 -6 weeks of growth. Thereafter, this value did not increase significantly. When several cultures of algae were successively grown in the same medium, or when culturing was carried out for a long time with frequent harvesting, the nitrogen content of the nutrient medium remained at approximately the same level as mentioned. The possible reasons for these observations are discussed.

The bleeding rate as well as transport of K + , NO 3 - and PO 4 --- within the bleeding sap of corn plants (Zea mays) has been studied in intervals after raising the nitrate concentration of the nutrient solution from 5 to 10 meq/1. Acceleration of the exudation process in response to increased nitrate supply is accomplished after a lag phase. During this lag phase ʟ-ethionine causes a marked stimulation of bleeding sap exudation. A very close correlation (coefficient of correlation r = 0,996) was found between bleeding rate and phosphate transport within the bleeding sap, whereas transport of K + (r=0,868) and NO 3 - (r=0,773) is not that closely correlated. Because phosphate is translocated to the Xylem after it has been metabolized in a series of organic phosphorous compounds it is concluded that the exudation process is primarily linked to oxidative phosphorylation in the root, which is apparently stimulated by ethionine after a lag period. Acceleration of respiratory chain phosphorylation may be brought about by increasing the amount of phosphate acceptors.

The development of extractable peroxidase activity in the mustard seedling is controlled by phytochrome (P fr ; operationally: Continuous far-red light) in an organ specific manner (enhancement in the cotyledons and taproot, inhibition in the hypocotyl; Tables I, II). Detailed kinetics of peroxidase accumulation in the cotyledons (Figs. 2, 3) reveal the existance of a two-step induction mechanism: 1. Formation of a stable transmitter during a period of competence to P fr (“determination phase“), and 2. development of peroxidase activity mediated by the transmitter during a later period of competence to the transmitter (“realization phase“). These two periods of seedling development are completely separated in time.

Singlet oxygen ( 1 Δg) was generated by a microwave discharge and bubbled through a solution of chlorophyll-a in dibutylphtalate at approximately 10-20 torr. It not only excited the dye to its first singlet state but also produced oxidized species which generated a very long lasting weak chemiluminescence. From quenching experiments for the generation of the excited species could computer simulation.

The effects of the saccharides on the volume of elastin are primarily “dehydrating” or “osmotic” ones, those of J - and Cl - are primarily “electrostatic” ones, and the effect of urea is predominantly a “denaturing” one.

The in v itro incorporation of 14 C-leucine by rat liver microsomes is studied under four different physiological states: 1. Norm al liver of adult rats (N L), 2. irradiated (4 000 rads) liver (IL), 3. liver after partial hepatectomy (RL) and 4. regenerating liver in preirradiated rats (IRL) 2, 5, 12, and 24 hours after treatment. Both irradiation and partial hepatectomy, when applied separately, stimulate the endogenous activity of microsomes, whereas preirradiation abolishes the stimulatory effect in the early hours after partial hepatectomy. The results are in agreement with the concept that irradiation stimulates the operating synthetic programme of the cell and inhibits cellular reprogramming.

The dependence on time of the dose-effect relationship was studied for the removal of 241 Am from the skeleton and liver of the rat by Ca-DTPA . Due to the linearity of the dose-effectcurves (in a log-log scale) as well as to the linear dependence of the slope on the logarithm of time, simple equations were derived which describe the mobilization of 241 Am as influenced by DTPA-dosage and time of treatment.

An in-vitro-method is described, which allows for a temporary suspension of the insulin sensibility of rat-diaphragm by treatment with trypsin. The time, during which insulin shows no effects (20-30 min), is used to test compounds which may or may not have insulin-like activity. If their activity doesn’t disappear, one may believe that the activity of the compounds in question is independent of the receptor.

Embryonic rat cells are stopped in G 1 -phase when they are incubated in serum-free medium. They can be triggered to proceed through their cell cycle by the addition of two proteins which have been isolated from fetal calf serum. The influence of calcium and potassium ions on the stimulation process has been exam ined: 1. Ca 2+ and K + ions simultaneously must be present in the culture medium in concentrations of at least 5x10 -4 ᴍ and 1x10 -3 ᴍ, resp. 2. The intracellular concentrations of both ions are increased by the serum factors. 3. The intracellular concentrations of K + strongly are dependent on the extracellular Ca 2+ -concentrations; they increase threefold between 5x10 -5 and 1x10 -3 ᴍ of Ca 2+ . On the other hand, the intracellular calcium concentrations are not significantly influenced by the potassium content of the culture medium.

Optomotor turning reactions were induced in worker bees by means of moving “polarisationpatterns”. The responses appeared only when the stimulating light was confined to the short wavelength part of the spectrum, and when the E-vector directions of the polarisation filters of whidi the pattern was composed were at ±45° to the vertical for stimulation of the front region of the eye. Assuming that the polarisation sensitivity of the individual receptor is independent of the wavelength of the light, the experiments show that at least two of the known three different types of colour receptors contribute to the optomotor turning reaction. These results are in agreement with the assumption, that the retinula cell output of each ommatidium is superimposed before the correlation for movement detection between different ommatidial channels takes place.

Keywords The large spindle-shaped micronucleus of Paramecium bursaria contains filaments of about 60 Å diameter between numerous highly condensed chromosomes. Following treatment for several hours with 10% heavy water the nucleus becomes streched to several times its original length. The filaments, whose number increases noticibly, then appear as an aggregate, which exhibits a somewhat paracrystalline arrangement. An examination of the filament aggregate by means of a laser diffractometer yielded two diffraction lines corresponding to longitudinal periodicities of 91 - 99 and 160 -195 Å. Since both periodicities are comparable to those reported for microtubular proteins, it is assumed the filaments reported here could be related to microtubular material.

Neuraminidase-treated erythrocytes coated with a variety of neuraminic acid-containing glycoproteins adsorbed influenza virus and neuraminidase-free hemagglutinins, but not purified neuraminidase. The results indicate that neuraminic acid is the binding site on the glycoprotein and that the rest of the molecule does not play a specific role in the reaction.

Endoribonuclease splitting single-stranded poliovirus RNA is associated with virions of the myxoviruses fowl plague virus and Newcastle disease virus. These virions are devoid of deoxyribonuclease hydrolyzing single-stranded M 13 phage DNA and ribonuclease hydrolyzing doublestranded poliovirus RNA. The latter enzyme, however, is present in allantoic fluids of infected chick embryos from which the virions are obtained.