Volume 36, Issue 9-10

of the genus Teucrium and 3 species of the genus Ajuga have been examined for iridoids. Besides the known compounds Harpagid, 8-O-Acetylharpagid, Ajugol, Ajugosid and Reptosid, which we have isolated from species of both genera, two new iridoids Teucardosid (1) [2] and Teuhircosid (5) have been isolated from Teucrium species only. The structure and relative configuration of the new compounds have been determined by spectroscopic methods fH-NMR, 13C-NMR, MS) and some chemical reactions. The taxonomic significance of our results is discussed.

Iridoids, 8-O-Acetylmioporosid, Clerodendrum, NMR, MS Clerodendrum thomsonae Balf. f. has been examined for iridoids. Besides the known compounds melittoside, aucubin, 8-O-acetylharpagide, reptoside and ajugoside a new iridoid, 8-O-acetylmioporoside, has been isolated using SC and HPLC. The structure and relative configuration of the new compound have been determined by spectroscopic methods (1H-NMR, 13C-NMR, MS) and by correlation with mioporoside.

Coniferyl Alcohol, Peroxidase, Lignin, 4-Chloroaniline, 3,4-Dichloroaniline Lignin was formed in vitro by the peroxidase/hydrogen peroxide mediated polymerization of coniferyl alcohol. In the presence of [14C]4-chloroaniline or [14C]3,4-dichloroaniline copolymeri­ zation occurred with incorporation rates of about 45 mol%. Co-elution of UV-absorbing material (reflecting lignin) and of incorporated radioactivity was observed on a calibrated column of Sephadex LH-60. This method indicated a broad molecular weight distribution of the copolymers with values of between about 20000 and 1000. Most of the copolymer products had apparent molecular weights near 1000. The 1H-NMR and 13C-NMR spectra of the copolymers were compared with those of in vitro lignin. The copolymer spectra showed a relative increase in aromatic peaks and a relative decrease in most of the typical lignin peaks. Three peaks indicative of a new type of phenyl-propanoid side-chain structure were detected in the 'H-NMR and 13C-NMR spectra of the copolymers. The corresponding 1H-NMR chemical shift values were 4.75 ppm (a-C-H), 4.40 ppm (β-C-H) and 3.70/3.50 ppm (y-C-H2). The 13C-NMR chemical shift values were 56.9 ppm (a-C), 84.3 ppm (β-C) and 60.0 ppm (y-C). These peaks were attributed to a 3-aryl-3-anilino-2-aryloxy-propanol-1 structure in the copolymers by analysis of coupling patterns and by comparison with spectral reference data. The NMR-results and experiments with catalase and inhibitors suggested that a major mechanism of copolymerization consisted of a nucleophilic addition of the anilines to the benzylic ar-carbon of lignol quinone-methide intermediates.

Two ferulic acid conjugates have been isolated from the extract of immature anthers of Tulipa cv. "Apeldoorn" and their structures elucidated using chromatography, electron impact mass spectrometry, and NMR spectroscopy. These two conjugates are 6,3'-diferuloylsucrose and 6,3',4'-triferuloylsucrose. High performance liquid chromatographic analysis of the extract showed that these esters are transient major constituents of the phenylpropanoid pattern of the immature anthers and are present in the ratio of 1:2. Previous investigations showed that these components are accumulated in the loculus.

The main components of the essential oil from Artemisia dracunculus L., as there are sabinene, methyl eugenol, estragol and elemicine, are present in variable quantities depending on the season. The biosynthesis of the phenolic compounds in tarragon is in accordance with the shikimate pathway. Elemicine is likely to be a metabolic product of shikimic acid with no further mono-or bisphenolic intermediates involved.

7-Hydroxy Tropolone, Bacterial Constituents, Pseudomonas sp. Structure elucidation and antibiotic activity of 7-hydroxy tropolone -a metabolite from Pseudomonas sp. — is reported.

Polymethylated Flavonols, Identification, Enzymatic Synthesis, O-Methyltransferase, Chrysosplenium americanum, Saxifragaceae The major flavonoid constituents of Chrysosplenium americanum (Saxifragaceae) were identified by UV-, NMR-and mass spectroscopy and the analysis of their hydrolytic products. They consisted of two 2'-O-β-D-glucosides of partially methylated 2'-hydroxyquercetin and four 5'-O-β-D-glucosides of partially methylated 6-hydroxyquercetin (quercetagetin). The O-methyltransferase system of this tissue can catalyse the stepwise O-methylation of quercetin, but not quercetagetin, to its 3,7,4'-triOMe-dervative. It is postulated that the latter compound may serve as a branching-point intermediate in the biosynthesis of the naturally occurring O-methylated flavonols of this tissue.

Enzyme preparations from flowers of Antirrhinum majus catalysed the oxidation of naringenin to apigenin and of eriodictyol to luteolin. Enzyme activity was found to be localized in the microsomal fraction. The reaction required NADPH as cofactor and had a pH optimum of about 7.0. The NADPH-dependent microsomal enzyme activity was also present in flower extracts of other flavone-producing plants, whereas flower extracts of plants which lack flavones were found to lack also this enzyme activity.

Soluble enzyme preparations from irradiated cell suspension cultures of parsley (Petroselinum hortense Hoffm.) catalyse the conversion of flavanone to flavone, dihydroflavonol and flavonol. These reactions require 2-oxoglutarate, Fe2+ and ascorbate as cofactors. In the presence of these cofactors conversion of dihydroflavonol to flavonol was also observed. With this system in vitro biosynthesis of radioactive flavone, dihydroflavonol and flavonol from [2-14C]malonyl-CoA and 4-coumaroyl-CoA in good yield and with high specific activity is possible. We postulate that synthesis of flavone and flavonol from flavanone proceeds via 2-hydroxy-and 2,3-dihydroxyflavanone, respectively, with subsequent dehydration. The microsomal fraction of the parsley cells contains an NADPH-dependent flavanone 3'-hydroxylase.

Dedicated to Prof. H. Zahn on the Ocassion of His 65th Birthday Zn+2/Co+2 Exchange, Microbial Acylamino Acid Amido Hydrolase, Aspergillus oryzae, Kinetic Properties The inactivation of the Zn+2 metallo enzyme acylamino acid amido hydrolase from Aspergillus oryzae by ethylendiamine-tetraacetate (EDTA) and nitrilotriacetate (NTA) and the effects of Phe and His on this process were studied. Reactivation of the enzyme by Zn+2-or Co+2-NTA buffer revealed a dissociation constant for the Zn+2-enzyme of 10~10 M and for the Co+2-enzyme of 10-7-5 m. The kinetic properties of the Zn+2 and Co+2 enzyme were compared for a series of substrates. Substitution of Co+2 for Zn+2 reduces substrate specificity of the enzyme.

2-Oxo-carotenoids, 2-Hydroxy-carotenoids, [uC]/β-Carotene, Metabolism, Stick Insects The carotenoids of the stick insect, Ectatosoma tiaratum, were studied by spectroscopic and chemical methods. The β,β-type pigments are β,β-carotene, β,β-caroten-2-one, β,β-caroten-2-ol, β,β-carotene-2,2'-dione, 2'-hydroxy-β,β-caroten-2-one, β,ε-carotene-2,2'-diol, 3,4-didehydro-β,β-carotene-2,2'-dione, 2'-hydroxy-3,4-didehydro-β,β-caroten-2-one, and 3,4,3',4'-tetradehydro-β,β-carotene-2,2'-dione. In addition, the following β,ε-type pigments were identified: β,ε-carotene, β,e-caroten-2-ol, and β,e-caroten-2-one. This is the first report on the occurrence of β,e-caroten-2-ol in an animal and of β,ε-caroten-2-one in nature at all. On treatment with BF3 in chloroform β,ε-caroten-2-ol is dehydrated to a specific product with the proposed structure of 2,3-didehydro-4,7'-retro-β, e-carotene. The biogenesis of the β,β-type carotenoids from β,ε-carotene is demonstrated by feeding [14C]β-carotene to the insects. Radiolabel was incorporated into all major metabolites of this type. The metabolism of carotenoids in stick insects is discussed applying the "half-molecule sub­ strate" hypothesis to the enzymic transformations of the pigments.

of Agaricus abruptibulbus, a mushroom which is known to accumulate cadmium, has been isolated and cultivated under definite conditions on agar plates or in a liquid medium in the absence and in presence of cadmium acetate. In.presence of 0.5-1.0 mg/1 Cd, mycelial growth of A. abruptibulbus is enhanced to 80% compared to the Cd-free controls, while above 4 mg Cd/1, the metal began to be inhibitory. The growth promoting effect of Cd was found to be independent from the supply of the organism with zinc. During growth in presence of Cd, an efficient uptake of the metal into the mycelium took place, a maximal 300 fold enrichment being observed with 10 mg Cd/1. Similar tests were performed with zinc, thereby showing a correlation between the uptake of both elements by the mushroom.

Cross-linking with glutaraldehyde has been successfully applied in order to analyze the kinetics of reassociation of oligomeric enzymes (R. Hermann, R. Rudolph, and R. Jaenicke Nature 277, 243-245 (1979)). In the present study the assembly of lactic dehydrogenase from pig heart is investigated using this approach. In order to eliminate perturbations caused by excessive folding reactions, acid dissociation was performed in the presence of 0.8 M Na2SO4 at 0°C . Under optimum conditions complete cross-linking of the tetrameric enzyme was achieved in less than 2 minutes. Cross-linking during reconstitution proves the dimer to be the only intermediate of reasso­ ciation. The dimer → tetramer transition is found to be rate-limiting for both reassociation and reactivation, suggesting the tetramer to be the enzymatically active species. The presence of monomers during reconstitution indicates that tetramer formation is preceded by a fast monomer-dimer equilibrium. The kinetic model describing the experimental data is characterized by an equilibrium constant K = 3 ± 1 · 107 liter · m ol-1, and a second-order rate constant k = 1.4 ± 0.2 · 104 liter · mol-1 · s-1.

The interaction of the coenzyme analogues pyridoxal (A), pyridoxine 5'-phosphate (B), pyridoxic acid 5'-phosphate (Q and N-phosphopyridoxyl-L-serine (D) with both the isolated apo β2 subunit and the native < x2 apo β2 bienzyme complex of tryptophan synthase from Escherichia coli has been investigated using enzyme kinetics and CD spectroscopy. A 500-fold molar excess of (A) yields a maximum activation of the a2 apo β2 complex of 12% compared to the native holo bienzyme complex. The corresponding Michaelis constant KM equals 0.16 mM. Compounds (B -D) which lack the reactive carbonyl group in the 4-position cannot act as cofactor during enzymic turnover. However, they are competitive inhibitors with respect to the natural coenzyme pyridoxal 5'-phosphate. The corresponding inhibition constants K\ are for (B): 0.10 mM, (C): 0.03 mM and (D): 0.16 mM. The CD spectra of the aromatic side chains of both protein species ([@]278nm for the β2 subunit = 26 degr cm2 decimol-1, for the bienzyme complex = 40 degr cm2 decimol-1) remain un­ changed and no measurable dichroic absorption is induced in the visible region at 415 nm upon addition of (A), (at this wavelength productive binding of pyridoxal 5'-phosphate induces a significant extrinsic Cotton effect in the internal aldimine). Reaction with (B) leads to an enhancement of the dichroic amplitude at 278 nm of the isolated β2 subunit {A[6] = 6 degr cm2 decimol-1) and of the a2 β2 complex (zl[0] = 17 degr cm2 decimol-1) respectively. Com­ pound (C) shows no effect in the aromatic region of the β2 subunit, but a decrease in the a2 β2 complex (A[0) = 5 degr cm2 decimol-1). At 315 nm, however, a remarkable extrinsic Cotton effect of + 20 degr cm2 decimol-1 is induced in (Q . Ligand (D) causes a similar increase at 278 nm of A[0] = 14 degr cm2 decimol-1 in both protein species. The given data are discussed on the basis of the mode of binding of the natural coenzyme.

Rhodopseudomonas palustris, Glutamine Synthetase Regulation, Adenylylation Glutamine synthetase from Rhodopseudomonas palustris is regulated via an adenylylation/deadenylylation mechanism. The enzyme purified from ammonia-grown cells, released AMP upon treatment with phosphodiesterase, along with drastic changes in its pH and metal dependency. Kinetic parameters for enzyme-substrate interaction were also dependent on the adenylylation state of the enzyme, as was the influence of several nitrogenous feedback inhibitors on the catalytic activity. The adenylylation state of the enzyme was modified in vivo by the availability of ammonia.

Ecdysteroid, Immunoadsorption of Steroids, Antiserum Specificity Two ecdysteroid-specific antisera, anti-ecdysone-albumin and anti-20-hydroxyecdysone-al-bumin, were induced in rabbits. The properties of both antisera were tested with a large number of ecdysteroids. The former antiserum was unique in its ability to discriminate between the moulting hormones, ecdysone and 20-hydroxyecdysone, whereas the latter had a broad specificity for ecdysone and several of its metabolites. y-globulin fractions of both antisera were covalently linked to Sepharose 4B and used as immunoadsorbents. These were able to bind ecdysteroids from crude extracts of insects. Bound ecdysteroids could be eluted quantitatively from the adsorbents using 3 M sodium trichloroacetate. When a mixture of ecdysteroids which contained ecdysone and at least six different ecdysone me­ tabolites were run over a column with anti ecdysone immunoadsorbent only ecdysone and its hy-droxyderivatives 20-and 26-hydroxy ecdysone were bound to and subsequently eluted from the adsorbent. In contrast a column with anti-20-hydroxyecdysone immunoadsorbent retained most of the different ecdysteroids due to the broader specificity of the antibodies. These immunoadsorbents provide the potential not only to purify ecdysteroids but also proteins crosslinked to ecdysteroids via photoaffinity labelling. It is well known that immuno-adsoiption is a powerful tool for the isolation of proteins. The results described here demonstrate that immunoadsorption may also be useful in the isolation of low molecular weight compounds of biological and medical interest.

Clotrimazole and triadimefon are known as potent inhibitors of ergosterol synthesis in pathogenic yeasts and fungi, respectively. As their mode of action generally the inhibition of sterol desmethylation reactions is accepted. We report about a second effect, a "feed-back" inhibition of 3-hydroxy-3-methyl-glutaryl (HMG)-CoA-reductase by accumulation of ergosterol precursors. Addition of lanosterol to intact cells leads to an inhibition of HMG-CoA-reductase as well, but not to fungistatic effects. From the reported data the influences of clotrimazole and triadimefon have to be considered as an inhibition of desmethylation reactions involved in ergosterol synthesis of yeasts and fungi with a concomitant decreased production of mevalonate.

The electron spin resonance (ESR) spectrum of erythrocytes of a healthy male volunteer exhibited 2 min after intravenous administration of 1 g of ascorbic acid a considerable increase in spin concentration and a new signal at about g = 2.005 which we previously had found to correlate to the semidehydroascorbate (SDA) radical and which is not identical with the O j radical. Moreover, the vitamin C concentration in erythrocytes and plasma was considerably higher than in comparable samples of other volunteers treated identically. In the latter cases, the ESR spectrum of the erythrocytes was not modified at all. These findings suggest that there must be a substance which reacts with ascorbic acid specifically. It can be assumed that the enzyme ascorbate oxidase plays this decisive role in the ascorbic acid metabolism. For this reason, different amounts of ascorbate oxidase have been added to healthy erythrocytes treated in vitro with ascorbic acid and to tissue samples of lung cancer. As expected, the vitamin C effect as expressed by the appearance of the SDA signal and the increase in spin concentration could be reversed. It is suggested, therefore, that in special types of cancer, such as acute lymphatic leukemia and lung cancer, the concentration of ascorbate oxidase or of an enzyme acting like it is, primarily, diminished, while in other types it might be enlarged.

The enhanced Raman effect from 5'-AMP adsorbed on the roughened silver surface is used to characterize hydrogen-deuterium exchange. SERS spectra of 5'-AMP present in H2O and D2O solutions at rather low concentrations were recorded in the spectral range of 2000 to 3500 cm-1. Surface enhanced Raman bands in this spectral range are found to increase in intensity, relative to bands of normal Raman solution spectra. In addition, one notes that the CH and CD stretching vibrations, almost obscured by H2O2 or D2O scattering, now stand out clearly.

Dedicated to Professor Dr. Joachim Kühnau on the Occasion of His 80th Birthday cGMP, DNA Polymerase Activity, DNA Polymerase A, DNA Polymerase I, Baker's Yeast DNA polymerase activity from extracts of growing yeast cells is inhibited by cGMP. Experiments with partially purified yeast DNA polymerases show, that cGMP inhibits DNA polymerase A (DNA polymerase I from Chang), which is the main component of the soluble DNA polymerase activity in yeast extracts, by competing for the enzyme with the primer-template DNA. Since the enzyme is not only inhibited by 3',5'-cGMP, but also by 3',5'-cAMP, the 3': 5'-phosphodiester seems to be crucial for the competition between cGMP and primer. This would be inconsistent with the concept of a 3'-OH primer binding site in the enzyme. The existence of such a site in the yeast DNA polymerase A is indicated from studies with various purine nucleoside monophosphates. When various DNA polymerases are compared, inhibition by cGMP seems to be restricted to those enzymes, which are involved in DNA replication. DNA polymerases with an associated nuclease activity are not inhibited, DNA polymerase B from yeast is even activated by cGMP. Though some relations between the cGMP effect and the presumed function of the enzymes in the living cell are apparent, the biological meaning of the observations in general remains open.

Biosynthesis of the plant sulpholipid (diacylsulphoquinovosyl glycerol) has been demonstrated in a cell-free assay system from the green alga Chlamydomonas reinhardii CW 15. The sulpholipid was labelled with [35S]sulphate when ATP, Mg2+ and a reductant were provided. Unlabelied cysteic acid failed to suppress the labelling of the sulphonate group in the lipid. Labelling with [35S]PAPS or [35S]sulphite has been studied in a fractionated cell extract. Sulphite as a precursor only required a particulate fraction of the cell while with PAPS the assay had to be complemented with a soluble protein and a thiol compound. [35S]PAPS was incorporated into the diacylsulphoquinovosyl glycerol with a higher specificity than sulphite.

Chromatography Light-grown non-dividing cells of Euglena gracilis Klebs var. bacillaris Cori form pheophytin a like pigments from chlorophyll a without loss of viability when they are allowed to incubate in darkness without shaking. This is accompanied by the loss of long-wavelength components in the red absorption band of intact cells. After extraction of these cells with acetone, transfer of the pigments to ether and treatment of the ether solution with dilute acid, two pigments can be separated by high performance liquid chromatography on reverse phase silica gel (RP-8) using methanol: water = 95:5 (v/v) as the eluting solvent: In addition to pheophytin a, the eluate contains an unknown pigment. With increasing times of incubation of the cells in darkness, the proportion of pheophytin a decreases and the proportion of the unknown increases suggesting, that the unknown is formed from pheophytin a. This pigment has been identified as pyropheophytin a. It has the same absorption spectrum as pyropheophytin a (prepared by pyridine pyrolysis of pheophytin a) and contains phytol as the longchain esterifying alcohol. On conversion to the methyl ester, the resulting methyl phorbide is identical with authentic pyromethylpheophorbide a by tic, hplc, absorption, absorption difference and mass spectros­ copy. This is the first report of pyropheophytin a or any pyrochlorophyll derivative from plants or oxygenic plant-like microorganisms where it may serve as an intermediate in chlorophyll degradation.

14C-and 15N-Assimilation, 15N-Labelled Amino Acids, M arine D iatom s The marine diatoms Bellerochea yucatanensis and Skeletonema costatum were grown at +20 °C in 0.03 vol.% CO2 with nitrate or ammonia. The 15N -am m onia and 15N -nitrate assim ila­ tion and 15N -incorporation into various amino acids were studied of both diatom s during exponential growth phase in dependence of different nitrogen conditions. In all experiments the 15N -am m onia uptake was lower than the 15N -nitrate assim ilation rate up to 20-40 min photo­ synthesis. N itrate lim itation -cells grown in nitrate followed by growth in nitrogen-free m edium for 24 h — caused a strong 15N-label into aspartate after adding 15NH 4C1 (1 m M). In cells grown in nitrate highest enrichment of 15N was found in glutamine. Results were discussed with reference to the operating of the GS/GOGAT system and glutam ic acid dehydrogenase pathway. Photosynthetic 14CO2 fixation experiments showed a very high labelling of aspartate which was interpreted with a phosphoenolpyruvate carboxylation catalysed by phosphoenolpyruvate carb-oxykinase.

Photosynthesis, D ark Fixation, β-Carboxylation, C 4-M etabolism , Brown Algae Marine brown macroalgae including Macrocystis integrifolia, Nereocystis luetkeana, Lessoniop-sis littoralis, Laminaria saccharina, Fucus serratus and some further representatives of the Laminariales and Fucales (Phaeophyta) have been investigated with respect to their remarkably high potential for β-carboxylation of phosphoenolpyruvate supplem enting photosynthetic CO2 fixation. Kinetic tracer studies indicate that 14C-labelling of C4 acids such as aspartate and malate is not restricted to dark periods, but also occurs during photosynthesis. Rates of carbon fixation into C4 compounds are approxim ately equal in the light and in the dark. Distribution of 14C between C 1 and C4 atoms of aspartate suggests carbon flow from early occurring photosynthates such as 3-phosphoglycerate to C4 compounds including aspartate and malate. In brown macro­ algae dark carbon fixation via β-carboxylation of phosphoenolpyruvate is therefore assumed to be quantitatively and qualitatively integrated into photosynthetic CO2 assimilation thus yielding appreciable 14C-labelling of C4 dicarboxylic acids. The underlying reactions and conversions are basically different from C4 photosynthesis and should preferably be term ed as C4 metabolism.

Several substituted diphenylethers were found to be effective inhibitors of photosynthetic electron flow in isolated thylakoid membranes from spinach chloroplasts. T heir site of inhibition was localized with artificial acceptor and donor systems. The phenylether of an alkyl substituted nitrophenol is prim arely inhibiting electron flow after plastoquinone function whereas a dinitro-phenylether of a phenyl substituted nitrophenol is inhibiting before plastoquinone function. Therefore certain diphenylethers interfere with plastoquinone function at the oxidation or reduction site, depending on the substitution.

The effect of trifluralin on the photosynthetic electron transport has been investigated by oxygen evolution and thermoluminescence m easurem ents. The results confirm the earlier observations that trifluralin at low concentrations blocks electron transport between the two photosystems probably at the same site as DBMIB does. At higher concentrations however, trifluralin inhibits the reaction from H2O →pBQ also and affects the thermoluminescence of chloroplasts in a manner sim ilar to DCMU. These results suggest that trifluralin has a second inhibitory site therefore the use of trifluralin as a specific inhibitor of electron transport has to be questioned.

The growth of Synechococcus at different intensities of white and red light caused changes in the pigment composition. The ratio of chlorophyll a to phycocyanin varied from 1:8,2 in LWLI-grown cells to 1:1,4 in cells grown at HWLI and to 1:15,7 in cultures exposed to HRLI. Acyl lipids were quantitatively determ ined and fatty acids of the individual lipid classes analysed by GLC. Phycocyanin-free photosynthetic lam ellae were obtained by fractional centrifugation. No variation was found in the acyl lipid composition of the m em brane preparations. These all contained MGDG, DGDG, SQDG and PG as components. In all the lipids investigated, palmitic, hexadecenoic and octadecenoic acids m ade up to more than 90% of total fatty acids. The pattern of these major components w ithin the lipids from the different cultures depended on the light used. No large differences were detected between zones obtained from LWLI and HRLI isolated membranes, whereas density gradient centrifugation of those from HWLI-grown cells resulted in a completely different pattern of bands. The variations in lipid and fatty acid composition are discussed with respect to changes observed in lipid composition of whole cells and the results reported on tem perature dependent shifts in lipid fluidity in cyanobacteria.

Purified hum an plasm a fibronectin has been shown to agglutinate protease-treated red cells [Vuento, Hoppe-Seyler's Z. Physiol. Chem. 360, 1327-1333, (1979)]. The present report shows that the activity is inhibited by low concentrations of lectins and by macrom olecular serum factors. Chemical m odification of carboxyl groups of fibronectin strongly inhibited the activity, but modification of am ino groups or guanidinium groups had little effect on the activity. The results suggest that fibronectin receptors on erythrocyte surface are carbohydrate-containing molecules. Humoral m acrom olecular factors may control the interaction of fibronectin with cell surfaces. Chemical m odification studies indicate that the parts of the fibronectin molecule responsible for the hem agglutinin activity are different from those mediating the binding of fibronectin to collagen.

Exposure to red light of high intensities leads to saponin and prolam ellar body degradation in etiolated Avena sativa seedlings. Exposure to red light of low intensities increases the saponin percentage found in prolam ellar bodies w ithout changing the overall saponin content. Proto­ chlorophyllide is assumed to act a decisive p art in the phototransform ation of the PLB as expressed by their saponin content. This is indicated by the action spectrum of this stim ulation as well as by experiments with long-wave red (729 nm) and A LA /LA treatment. In weak light the pchlide phototransformation is decelerated-probably due to lack of energy. The PLB are inter­ preted to be modified by the increased pchlide concentration so that more saponin can be incorporated. In further experiments a barley m utant (albina f 17) lacking the capacity to esterify phytol as well as the capacity to degrade the PLB during the greening process was investigated. The results substantiate our hypothesis, as PLB transform ation — indicated by PLB saponin concentration — is decelerated with increasing pchlide concentration in greening etioplasts.

A structural study of the synthetic phospholipid, L-a-dimyristoyl lecithin (DM L), has been m ade by X-ray fiber diffraction methods. Three different types of oriented specimens were prepared. They were X-ray photographed under the same conditions, including tem perature and relative humidity. T hree different types of diffraction patterns, corresponding to different confor­ mations and/or packing arrangements, were found. They are characterized by their unit cell dimensions, space groups, molecular conformations, and packing arrangements.

Carefully performed pulse titration of the isolated rat liver in the course of continuous erythro­ cyte free perfusion with small amounts of digitonin causes a short term perm eability of liver cell plasma membranes with concomitant short lived release of intracellular low or high molecular compounds such as ATP or lactate dehydrogenase. Gluconeogenesis from lactate being completely inhibited during this period restores w ithin about one m inute up to a level that depends on the am ount of perfused digitonin. The described experimental m odel is suggested to be useful for the measurement of cytoplasmic m etabolites under physiological conditions. It moreover offers the possibility to im port foreign substances into liver cells th at normally do not penetrate liver cell plasma membranes.

In spite of its very low concentration, the potato leafroll virus (PLRV) can be enriched from leaf-homogenates of the infected host plant Physalis floridana by a series of separation steps and purified by ultracentrifugation through layers of cesium chloride of defined density. U nder the present experimental conditions the virus accumulates as an invisible band in a region where the density of CsCl is 1.39 ± 0.01 g/cm 3. In negatively stained preparations, the virions show a diam eter of 23 nm and some morphological criteria indicate an icosahedral symmetry.

To describe a metastable electrical dipole state in a biological system. Fröhlich suggested a nonlinear model potential. In this paper we investigate a system of two such dipoles coupled by a dipole-dipole interaction. M athem atically this model is described by two coupled nonlinear differential equations. In the investigation of the dynamics of the system we distinguish three solution types of the equations of motion.

The novel liehen substance porphyrilic acid methyl ester and pannaric acid are reported the first time in the lichen genus Psoroma. They are constituents in the two varieties of the new species Psoroma tenue as well as in members of the Psoroma hypnorum/paleaceum aggr. and in a hitherto underscribed species from the southern hemisphere. Both dibenzofuranes are characterized by mass spectrometry and UV/VIS spectroscopy. A third compound of unknown structure (Ut) has been found additionally in the two varieties of P. tenue and in some specimens of the P. hypnorum/paleaceum group.

The glaucous epicuticular layer on the undersurface of the leaves of Polypodium glaucinum and the white exudate material on the lower surface of the sterile pinnae of Plagiogyra formosana is shown, mainly by spectroscopical methods, to consist of a mixture of 9(ll)-femene and 21-epi-9(l l)-femene, in both instances in a ratio of ca. 4:1. The 13C-NMR spectrum of 9(ll)-femene has been re­ corded and partially assigned.

The initial phases of growth induced by sterylglucosides were investigated by means of a high resolution recording technique. Avena coleoptile segments were preincubated with 10-6 M IAA in buffered solution, then the β-vglucosides of sitosterol, stigmasterol, campesterol, and cholesterol respectively were added in the concentration range from 10-7 –10-6 m . It could be demonstrated that the first response to the applied sterylglucosides is a reduction of the growth rate lasting about 15 min, followed by a sharp increase of the growth rate. As the growth response of the coleoptiles after treatment with sterylglucosides is very similar to that observed after application o f IAA alone, it is concluded from the results that sterylglucosides or sterols may also exhibit their primary action at the membrane level, perhaps by influencing microviscosity of the membrane and/or H +-secretion.

To elucidate the molecular mechanism of the direct allosteric exchange of oxygen and hydrogen carbonate in the hemoglobins of crocodiles, the N-terminal sequence of the β-chains of the crocodiles of the Nile (Crocodylus niloticus) and of the Mississippi (Alligator mississippiensis) was studied. The N-terminal end of the peptide is blocked. By mass spectrometry the N-terminal sequences of both species were found to be N-acetyl-alanyl-seryl-phenyl-alanine. These data explain the absence of hemoglobin-phojphate interaction, the data are in good agreement with the stereochemistry postulated for allosteric exchange of oxygen and hydrogen carbonate in crocodilian hemo­ globins.

The nonionic surfactant Tween 20 was applied intra-peritoneally to NMRI and Swiss mice on day 9 of gestation. It caused embryonic death and malformations of the verte­ brae, ribs and, in lower frequency, of the limbs.

Synechococcus (Anacystis nidulans, strain L 1402-1) were grown at + 37 °C in an atmosphere of 0.04 vol.% CO2 using different light conditions. Changing the culture conditions caused alterations in pigment ratios and ultrastructure of Synechococcus. In comparison to the low white and red light grown cells under strong white light the number of thylakoids decreased and an accumulation of storage carbohydrates could be observed. The number of the polyhedral bodies also varied with culture conditions. The results are discussed with reference to the pigment composition and the function of the polyhedral bodies.

The contrast-response function of a class of first order intemeurons in the fly's compound eye approximates to the cumulative probability distribution of contrast levels in natural scenes. Elementary information theory shows that this matching enables the neurons to encode contrast fluctuations most efficiently.