Band 36, Heft 11-12

In young plants of Eucalyptus globulus the leaves are covered with a whitish epicuticular layer. This leaf wax contains small amounts of C-methylated flavones as aglycones. A novel flavone has now been identified as 5,4′-dihydroxy, 7-methoxy, 6-methyl-flavone (8-desmethyl-sideroxylin). Another minor external flavone is chrysin. On leaves of E. sieberi the flavanone pinocembrin could be detected. It is shown that the four C-methylated flavones, eucalyptin, 8-desmethyl-eucalyptin, sideroxylin, and 8-desmethyl-sideroxylin are present in the leaf wax of 8 species analyzed. The same flavones are present on leaves of Kalmia latifolia.

Crude extracts from young Robinia pseudoacacia seedlings, shoots, and callus tissue catalyze the para-O-methylation of apigenin to acacetin using S-adenosyl-ʟ-methionine as methyl donor. Optimum activity was exhibited at pH 9.0, and Mg 2+ was not required for maximum activity. EDTA (10 mᴍ) did not affect the reaction rate, but 47% inhibition was observed with SAH (100 μᴍ). β-Mercaptoethanol (5 mᴍ) was required in the homogenization medium for optimum O-methyltransferase activity. Apigenin (K m , 50 μᴍ) was the best substrate, but significant activity was shown towards caffeic acid, 5-hydroxyferulic acid, naringenin, and quercetin. Paracoumaric, ferulic, and sinapic acids were not methylated. The K m for S-adenosyl-ʟ-methionine was 31 μᴍ. Our demonstration of a para-O-methyltransferase activity methylating apigenin, but not para-coumaric acid, strongly supports the conclusion that the B-ring methylation pattern of acacetin is determined at the C 15 -level in Robinia pseudoacacia.

ᴅʟ-[β- 14 C] 3,4-Dihydroxyphenylalanine (DOPA), [2- 14 C]pyruvate and [2- 14 C]acetate were ad­ministered to a callus culture of S. hassjoo and incorporation of the radioactivity into 3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (I) and 1-methyl-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (II) was examined. Incorporation of radioactivity from labelled DOPA into I and II, and from acetate into I were observed, while that from pyruvate into I and II and from acetate into II were hardly detected. The biosynthetic pathways of I and II were discussed.

Several lines of the genetically well defined Matthiola incana (Brassicaceae) concerning the anthocyanin biosynthesis (line 02, 06, 10, and 14) store the anthocyanin pigment as crystals (line 06) or in anthocyanoblasts (“balls”) in the epidermal cells (line 02, 10, and 14) of the flower petals. The genetic constitution of these genotypes is in addition to the basic factors f + , g + , and e + , b + b + or bb (cyanidin or pelargonidin type), ll, u + u + , and v + v + or vv, demonstrating that the ll, u + u + constitution is responsible for precipitation of anthocyanins in a certain structure indepen­ dent of the other modificationally acting genes b and v. The ll, u + u + types accumulate preferentially acylated 3-biosides.

The complex volatile secretion from the mandibular glands of Andrena haemorrhoa (Hym., Apoidea) has been analysed by GC/M S. It is composed primarily of three groups of compounds: 1. Spiroacetals of five different systems: two 1,6-dioxyspiro[4.4]nonanes, four 1,6-dioxaspiro[4.5] decanes, two 1,7-dioxaspiro[5.5]undecanes, one 1,6-dioxaspiro[4.6]undecane and one 1,7-dioxa-spiro[5.6]dodecane. 2. Straight chain fatty acid derivatives: methyl ketones, primary and secondary alcohols, acetates and hydrocarbons. 3. Isoprenoids: geraniol and geranyl acetate. Mass spectral fragmentation patterns have been studied for several synthesized spiroacetals.

The structural and kinetic properties of xanthine dehydrogenase (EC 1.2.1.37) from the facultative phototrophic bacterium Rhodopseudomonas capsulata were studied. The enzyme was fully induced when hypoxanthine or xanthine, but less effectively when uric acid served as nitrogen source during growth. The enzyme was purified about 2300-fold from cells grown photosynthetically with hypoxanthine as N-source by using ammoniumsulfate precipitation, gel filtration, ion-exchange and affinity chromatography. The molecular weight as determined by gel filtration throug Sephacryl S-300 was 345000. Subunit analysis by sodium dodecyl sulfate gel electrophoresis suggested a composition of four identical subunits with a molecular weight of 84000. The enzyme contained 2 flavin, 2 molybdenum and 8 iron-sulfur groups per mol. The turnover number with hypoxanthine and NAD as substrates was 12000 min -1 . Hypoxanthine, 1-methylhypoxanthine, 8-azahypoxanthine, xanthine, 1-methylxanthine, 2-hydroxypurine, 6,8-di-hydroxypurine, 5-azacytosine and 5-azauracil served as electron donors. The most effective electron acceptor was NAD. The kinetic constants (K m ) were (in μm): 52.5 (hypoxanthine); 32.5 (xanthine) and 61.2 (NAD). Various purine compounds inhibited the enzyme competitively in respect to hypoxanthine as substrate. Although reduction of uric acid to xanthine was not detected by using purified enzyme preparations, in vitro-experiments with 14 C-labelled uric acid indicated that the enzyme xanthine dehydrogenase participates in uric acid degradation in Rps. capsulata. According to their electrophoretic mobilities, the xanthine dehydrogenases isolated from hypoxanthine-and uric acid-grown cells were identical.

Transfer of heterotrophically grown cells of the unicellular green alga Chlorogonium elongatum to autotrophic growth conditions causes a 10 -15 fold increase in the amount of the chloroplastic enzyme ribulose-1,5-bisphosphate carboxylase. This increase was found to be due to de novo synthesis. The relative proportions of large and small subunits of the enzyme do not change. Their ratio is close to 3.4, the proportions in weight of the two subunits in the holoenzyme. Continous labelling with [ 35 S]sulfate reveals that the ratios of incorporation into large and small subunits are essentially the same in autotrophic and heterotrophic cells. Pulse-chase experiments show that the subunits are degraded synchronously. The coordinated subunit synthesis cannot be uncoupled using inhibitors of protein and RNA synthesis or high temperature of cultivation of the alga. The results suggests a very tightly coordinated synthesis of the large and small subunits of ribulosebisphosphate carboxylase.

The kinetics of inactivation of the Zn 2+ -metalloenzyme acyl-amino acid amido hydrolase by chelating ligands were studied. The rate of inactivation by 1,10-phenanthroline is enhanced by histidine and inhibited in the presence of phenyl-alanine. Removal of the metal ion increases the heat stability and decreases the pH stability of the enzyme. Reactivation of the inactive metal free enzyme is possible with Zn 2+ and Co 2+ . Titration of the metal free protein with a Co 2+ /nitrilotriacetate metal buffer revealed a dissociation constant of about 10 -7 ᴍ for the Co 2+ enzyme (Zn 2+ enzyme = 10 -10 ᴍ). The Co 2+ substituted enzyme is less stable than the Zn 2+ enzyme. Histinide and phenlalanine protect the Co 2+ enzyme against inactivation by 1,10-phenanthroline.

4-thiouridine crystallizes from butyric acid in the form of yellow needles, monoclinic space group P2 1 with a = 10.136 (3), b = 4.843 (2), c = 11.257 (3) Å, β = 93.91 (5) °. The crystal structure was solved on the the basis of 895 X-ray counter data using direct methods and refined to a reliability index of R = 5.6%. 4-thiouridine is in the anti conformation, the torsion angle O(1′)-C(1′)-N(1)-C(6) being 26.5°. Pseudorotation parameters τ max = 41.1° and P = 15.7° refer to C(3′)-endo ( 3 E) envelope form of the ribose. The conformation about the C(5′)-O(5′) bond is gauche, gauche. The present structure is compared with the previous one, crystallized from water as sesquihydrate and existing as the syn conformer (W. Saenger and K. H. Scheit, J. Mol. Biol. 50, 153-169 (1970). The influence of crystal packing forces on flexible molecules such as nucleosides is discussed.

α-Amino and α-carboxylate group protected aspartate (Z-asp-OMe) and glutamate (Z-glu-OBZl) solutions in CH 2 Cl 2 are studied as function of the addition of the respective salts by IR spectroscopy. The antisymmetrical stretching vibration of the -CO 2 c- groups shifts to the position where v C = O of the acid groups is observed, indicating that both anions in the acid-anion complexes are strongly influenced by the proton. With the formation of these complexes a continuum arises preferentially in the region 1600-900 cm -1 demonstrating that the OH · · · O - ⇌ - O · · · HO bonds formed show great proton polarizability. These hydrogen bonds are short and the proton potential is probably a broad flat well. The degree of the formation of these hydrogen bonds is determined. Finally, it is discussed that positive charge can easily be translocated via such hydrogen bonds in protein molecules.

The effect of pH and inositol hexaphosphate (IHP) on the symmetry of the heme environments in opossum (Didelphius marsupialis) and New Zealand White rabbit hemoglobins has been studied using electron spin resonance (ESR). Each methemoglobin is found to contain two different heme environments as detected by the rhombicity observed in the ESR spectrum. In both cases the rhombic nature of the ESR spectrum is influenced by pH and IHP binding, although in the case of rabbit methemoglobin the high spin ESR signal disappears above pH 8.0. In both hemoglobins, amino acid alterations in the α-chains are known to affect the properties of the ferrous derivatives. It is concluded that these alterations also provide the basis for the ESR spectral properties observed with the methemoglobins.

Membrane bound, Triton X-100 solubilized bovine nucleus caudatus acetylcholinesterase is sedimenting in presence of Triton X-100 concentrations higher than the CMC as a 10.5 S-detergent-enzyme complex. There is evidence that this complex does neither represent the molecular enzyme arrangement present in the membrane, nor the molecular form originally released from the membrane. The purified, cytoplasmatic acetylcholinesterase is sedimenting as a 10.5 S-form too. This form is clearly to be distinguished from the detergent enzyme complex, for it is obviously not capable of aggregating, whereas the 10.5 S-detergent-enzyme complex aggregates on detergent removal to defined water soluble oligomers with sedimentation coefficients of 16 S (700000 ± 10000), 20.6 S (960000 ± 60000) and 23.3 S (~ 1200000). In contrast to acetylcholinesterase from erythrocytes this aggregation is not easily reversibly by incubation with Triton X-100, reflecting differences in the hydrophobic part of the enzymes. Purified acetylcholinesterase solubilized without detergent under autolytic or tryptic conditions is mainly sedimenting as a 4.5 S-form. Such slow sedimenting forms detected in crude solubilisates of neuronal tissues, may originate at least partially form autolytic solubilization.

The organization of sequences homologous to the bovine 1.715 satellite DNA was studied in the bovine genome. A novel family of sequences, containing different numbers of copies of the 1.4 kb satellite period alternating with 1.2 kb sequence not related to this satellite, was found. Possible mechanism of the generation of these sequences is proposed.

The partial-denaturation map of T4 DNA is obtained by using benzyldodecyldimethyl ammonium chloride in the presence of a high concentration of formamide. In this way suitable conditions for preparation of electron microscope specimens and partial denaturation within a temperature range low enough to minimize the endonucleolytic cleavage, are realized. It is found that, under our experimental conditions, the denaturation increase depends mainly on the appearance of new denaturation sites rather than on the lengthening of DNA segments already denatured. Because of the DNA circular permutation it is necessary to align the measured maps to obtain the denaturation pattern. This is done through a computer program and informations on the distribution of the regions with highest (A-T) content along the genome are obtained. The results of contour length measurements of λ and T4 DNA’s are also reported.

1-anilino-naphthalene-8 -sulfonate (ANS) fluorescence measurements have revealed that red blood cell membrane of the Rh null type undergoes a transition at about 16 °C. In contrast, viscosity measurements of the extracted membrane lipids showed the usually observed transition at about 18 °C. Lower values of titratable sulfhydryl (SH) groups were observed in Rh null membrane using 5,5′-dithiobis-(2-nitro-benzoic-acid) (Nbs 2 ). In contrast, disulfide bonds in Rh null membrane were estimated to be about 3 times the value of the controls. Spin labeling experiments using 2-(3-carboxypropyl)-4, 4 dimethyl-2-tridecyl 3-oxazolidinyl-oxyl were carried out with phospholipase A 2 modified membranes. The mobile part of the spectra was significantly increased on the Rh null membrane. In the presence of ᴅ-glucose, infrared spectrometry showed a larger reduction of the intensity of the POO-band in Rh null membrane. In contrast to controls, binding of the reagent diethylpyrocarbonate resulted in no significant changes of the Rh null membrane as determined by electron spin resonance (ESR) measurements. ᴅ-glucose transport activity was found to be at the upper level of a group of Rh positive and Rh negative persons. It is suggested that the intensity of the polar protein-lipid interaction is reduced in Rh null membrane.

Vesicles prepared from the microsomal membrane fraction of maize coleoptiles possess an ATP-fueled H + -transport into the vesicles. It is highly possible that the vesicles from the microsomal membrane fraction actually are unchanged, native vesicles (originating from the ER or Golgi-apparatus) that can fuse with the plasmalemma or the vacuole. Therefore, they can reflect properties of the vacuole or the plasmalemma. The energy dependent acidification within the vesicles, which can be completely reverted through the addition of CCCP, was determined on the basis of photometric difference spectra using NR (Hager et al., Z. Naturforsch. 35 c, 794-804 1980). The proton pumps possess a very high substrate specificity; only ATP (+ Mg 2+ ) can be used as substrate, while GTP, ITP, UTP and CTP or other nucleoside tri- or diphosphates cannot be used. DCCD and DES inhibit H + -ATPase completely, oligomycin has only a slight, orthovanadate no inhibitory effect at all. The energy dependent transport of H + across the membrane takes place only in the presence of Cl - or Br - (not as well in the presence of I - ). Other anions (F - , NO - 3 , SO 2- 4 , SCN - , IDA - , H 2 BO - 3 cannot cause an intravesicular acidification through ATP if chloride (or Br - ) is not present. In the presence of chloride, however, some of these anions inibit the H + /Cl - -symport (J - , NO - 3 , SO 2- 4 , SCN - , H 2 BO - 3 ). They obviously are in competitive interaction with Cl - ions for Cl - -binding sites on a carrier or channel without being able to be transported themselves. Pi, which renders the acidification of the vesicles at a low rate possible without Cl - , is the only tested anion which can augment the Cl - dependent acidification. This supports the idea that either P i functions as a positive effector on the Cl - transport or that a Cl - /P i -antiporter exists which reduces Cl - accumulation and therefore facilitates the Cl - coupled H + transport into the vesicles also. The anion transport inhibitor, DIDS, blocks the ATP-dependent H + -transport. This again supports the idea of a relatively tight coupling between H + and Cl - transport in a possibly electroneutral system. The presence of monovalent cations, such as K + , Na + , Li + and choline + , are not important for H + transport. The dependence of the ATP-fueled acidification of the vesicles on the same anion pattern which seems to regulate elongation growth and stomata aperture speaks for the eminent importance of the H + -pump and vesicles described in this report for growth and turgor of plant cells.

Microsomal vesicles prepared from the ER and the Golgi apparatus of maize coleoptiles possess an ATP-fueled, Cl - -dependent proton pump which can cause an intravesicular acidifica­tion of the vesicles (A. Hager and M. Helmle, Z. Naturforsch. 36 c, 997 (1981); A. Hager et al., Z. Naturforsch. 35 c, 783-793 (1980)). This acidification is very specifically inhibited by Ca 2+ . The inhibition is already distinct at concentrations of 30 μᴍ. While 10-fold higher concentrations of La 3+ produce similar effects, Mg 2+ remains ineffective even at very high concentrations. If Ca 2+ is added after acidification of the vesicles, a rapid H + -efflux proportional to the amount of Ca 2+ added characterizes the first reaction phase. In the second reaction phase acidification within the vesicles commences anew, however, at a reduced rate. If Ca 2+ is added to vesicles whose proton pump has been inhibited by DCCD, the first reaction phase remains unchanged, while the acidification in the second reaction phase does not set in, and only a leak out of protons is observed. These results give support for a H + /Ca 2+ -antiporter mechanism which can function as a secondary energized Ca 2+ -pump and regulate the Ca 2+ -concentration in the cytoplasm.

Cooling A. nidulans or P. cruentum from 26 °C to 4 °C results in progressive spectral changes. The most significant changes are increases in absorbance at 690 nm (photosystem II), 678 nm (antenna chlorophyll), 625 nm (phycocyanin), and 505 nm (electrochromic band). In the case of P. cruentum there are also increases in absorbance at 568 and 545 nm (B-phycoerythrin) and a decrease at 587 nm. The spectral changes in both organisms are accompanied by decreases at 703 nm (photosystem I or aggregated chlorophyll), 650 nm (allophycocyanin) and 486 nm (carotenoid). Heating A. nidulans or P. cruentum from 4 °C to 44 °C results in increases in absorbance at 705 nm (photosystem I) and 486 nm (carotenoid), accompanied by decreases at 690 nm (photo­ system II), 676 nm (antenna chlorophyll), 628 nm (phycocyanin), 507 nm (electrochromic band) and 469 nm (carotenoid). In the case of P. cruentum there are also decreases at 568 and 546 nm (B-phycoerythrin) and an increase at 587 nm. The possible origin of the spectral change at 587 nm. The possible origin of the spectral change at 587 nm is discussed. The spectral changes of the chlorophyll bands (703, 690, 678 nm) and the electrochromic band (502 nm) are associated with phase changes of the lipid membrane. Lowering the temperature results in a decrease of aggregated chlorophyll or photosystem I, and vice versa. These spectral changes are also observed in green chloroplasts. The spectral changes of the phycobilins may originate from a temperature dependent change of the ion balance of the thylakoid. A spectral change may result from the ensuring modification of the stacking or from an electrochromic effect.

Linolenic acid induces changes in the absorption spectrum and in the picosecond fluorescence of pea chloroplasts. The effects of linolenic acid are dependent on concentration and time. Linolenic acid increases the fluorescence life time of chloroplasts at room temperature. The contribution of the slow fluorescence component relative to the fast component is increased almost 10 fold in the presence of 0.5 mᴍ linolenic acid. The synergistic action of digitonin and linolenic acid increases the ratio of “closed” to “open” traps in the photosynthetic units. Upon addition of 0.5 mᴍ linolenic acid there are increases in absorbance at 676 and 436 nm, and decreases in absorbance at 705 and 496 nm. Some of the spectral changes have a biphasic character, they reach a maxi um um after about 30 min then start to reverse. Based on the spectral changes at 496 and 705 nm it appears that linolenic acid has at least two effects, i.e. it modifies the thylakoid membrane and secondarily decreases the concentration of P700, respectively.

Rhodopseudomonas capsulata E 1 F 1 bacteria photo-assimilated nitrate under anaerobic conditions, but were incapable of reducing it in the dark. The bacteria utilized dissolved N 2 as nitrogen source, but the growth in the presence of nitrate was 5-fold higher. Nitrite was excreted to the medium, but not stoichiometrically with respect to nitrate consumption. Nitrate reductase is particulate and used reduced viologens or flavins as electron donors for nitrate reduction. The enzyme was inhibited in vitro by KCN, NaN 3 , dithioerythritol and mercurials. Ammonia and other sources of reduced nitrogen repressed nitrate reductase synthesis.

Assimilatory nitrate reductase was particle-bound in extracts from Azotobacter vinelandii. Nitrate reduction by particle fractions was dependent on NADPH and a particle-bound electron carrier. When the enzyme was solubilized from the particles by treatment with detergents, the particle-bound electron carrier could be substituted by ferredoxin or flavodoxin. Flavodoxin reduced at the expense of photoreduced deazaflavin was much more efficient than ferredoxin in transferring electrons to nitrate reductase. The addition of both ferredoxin and flavodoxin to the assays with photoreduced deazaflavin gave additive effects. With the solubilized enzyme, NADPH only poorly supported nitrate reduction even after the addition of electron carriers. The experiments indicate that A. vinelandii utilizes an electron transport chain between NADPH and nitrate reductase with some properties similar to those described for the generation of reductants to nitrogenase.

Photosynthetic and respiratory electron-transport reactions by the blue-green alga, Anabaena variabilis, exhibit a strict temperature dependence in vivo as well as in the cell-free system. The ratio of respiratory oxygen uptake in the dark and oxygen evolution in the light is high after growth at low temperatures (20 °C) and low after growth under optimum temperatures (28 °C). Respiration and photosynthesis show different break temperatures in the Arrhenius plots. Increase of growth temperature yields higher break points for photosynthetic or respiratory electron transport as well. These data are taken as evidence that photosynthetic and respiratory electron transport chains are embedded in different membrane areas.

The binding of the photosystem II herbicides diuron (DCMU), atrazine (s-triazine), ioxynil and dinoseb (substituted phenols) to isolated spinach thylakoids was saturated in less than 2 min in the dark. In intact cells of the green alga Ankistrodesmus b. it took 10 to 20 min to reach the binding equilibrium. Binding affinity of diuron, atrazine, dinoseb, measured as equilibrium binding constants, was found to be comparable in isolated thylakoids and intact algal cells. For ioxynil, reduced binding affinity was observed in algae. The concentration of binding sites in thylakoids and intact cells was determined to be 300-500 chl/inhibitor binding site, suggesting a 1:1 stoichiometry between bound herbicide and electron transport chains. In intact cells only the phenol herbicides ioxynil and dinoseb showed increased concentrations of binding sites. Strong correlation of herbicide binding and inhibition of electron transport was found for diuron in isolated thylakoids and intact cells. In thylakoids this is valid also for atrazine and dinoseb. For ioxynil a difference between the amount of binding and inhibition was found. This correlation of herbicide binding and inhibition proves that binding specifically occurs at the inhibition site at photosystem H. In addition to the specific binding, for all four herbicides studied, (except for ioxynil in thylakoids) unspecific binding was observed in thylakoids as well as in algae, which was not related to inhibition.

We simultaneously measured polymerization and ATPase activity of actin induced by cytochalasin B. It was found that under all conditions tested, ATPase activity was proportional to the concentration of actin which was unpolymerized. In addition, it was found that conditions increasing ATPase activity also increase the velocity of polymerization. From this we conclude that CB-induced ATPase activity is a property of the actin monomers and that the “readiness” of the monomers to hydrolyze ATP is correlated with an increased capacity of the monomers to polymerize.

The reaction rates of ATP formation from ADP and inorganic phosphate (P i ) by the catecholamine storage organelles isolated from bovine adrenal medulla accelerated 5-6 fold, when P i was added at various times after addition of Mg-ADP, as compared to the rates observed when the reaction partners were added simultaneously. The increase of the rates of ATP-P i exchange upon subsequent addition of P i to Mg-ATP was less prominent. Mg-ADP induced a ΔΨ (60-70 mV, positive inside), almost equal that induced by Mg-ATP. In both cases ΔΨ was significantly higher in the absence of P i than in its presence. At pH 7.4 of the medium the ΔpH was 1.4 units indicating an internal pH of 6. It was stable during the reaction time in the presence of Mg-ATP, while in the presence of Mg-ADP the internal pH increased gradually by 0.2 units. Both the ATP forming reactions as well as the nucleotide induced ΔΨ were uncoupler-sensitive (CCCP). Though inhibiting ATP formation from ADP + P i by 50%, 0.1 mᴍ AP 5 A (an inhibitor of adenylate kinase) did neither affect ΔΨ nor ΔpH, hence ruling out the possibility that ΔμH · induced by Mg-ADP would be actually due to ATP formed from ADP. Membrane ghosts were not able of ATP synthesis (in the absence of valinomycin), the ATP-P i exchange was only 10-20% of that of intact organelles, due to the low ΔμH · in the absence of intravesicular soluble constituents. It is proposed that the energy for ATP synthesis is furnished by the high gradients of protonated soluble constituents in the intact organelles.

The immobilization of erythrocyte as the whole cell without hemolysis was studied. It found that erythrocyte could be treated and immobilized stably by radiation polymerization of specific monomers having high viscous and long oxyethylene units chain such as methoxypolyethylene-glycol methacrylate (M-23G) and polyethyleneglycol dimethacrylate (14G). Irradiation dose without hemolysis was limited less than 1 × 10 5 r and a comonomer system consisting of M -23G-14G, 1:1 and small quantity of glutaraldehyde (GA) was the optimum carrier composition. The functional properties of the immobilized erythrocyte was also investigated. It was found that the immobilized cell could be carried out carbon monoxide-oxygen gas exchange effectively and reversibly so as in the intact cell. The immobilized erythrocyte also showed the catalase activity just as in the intact cell. The stability of erythrocyte increased greatly by the immobilization for standing at low and room temperatures and hardly hemolyzed in non-isotonic medium such as pure water. It was observed in scanning electron microscope that the immobilized erythrocyte had a hollow disk shape same as in intact cell and covered with a thin polymer layer.

We have performed experiments on the influence of Li + offered through drinking water i) on the period length (τ) of the rhythm in the flight activity of bats under LL and ii) on phase angles during entrainment under LD cycles. Bats subject to entrainment exhibited no qualitative and quantitative change in Ψ values after Li + treatment. In contrast the ingestion of Li ions by bats under free-running conditions shortens the τ of the bat rhythm by an amount that is a function of period length prior to ingestion, τ is, thus homeostatically conserved in the face of Li administra­ tion in bats.

Reversed phase high performance liquid chromatography offers an efficient and rapid method for analysis of steroidal saponins. Crude extracts from primary leaves of Avena sativa and isolated etioplasts therefrom have been resolved into four saponins (avenacosides) using a water-acetonitrile gradient system on RP-8 and monitoring the column effluent at 200 nm with an UV-detector. Detectability was found to be in the range of 50 ng avenacoside B and the detector response was linear up to 8 μg tested. The described method is applicable to studies on localization and physiology of Avena saponins during development of the primary leaf.

The volatile metabolites of three strains of Ceratocystis fimbriata (Ascomycetes) have been investigated. In the steam distillates of Strain 835 C several monoterpene hy­ drocarbons and alcohols as well as other metabolites could be identified. Mycelial growth and accumulation of the main components have been analyzed throughout the culture period on a defined synthetic cultural medium.

The liquid CO 2 -extract of aged burley tobacco was investigated for its content of diterpenoids, which are considered as important precursors of flavour constituents. Among several cembranoids, already known from various tobacco types, 4,8-dimethyl-8-hydroxy-11-(1-methyl-ethyl)-14-oxo-pentadeca-5,9-diene-4-olide, a new natural product, could be identified, evidently originating from 2,6,11-cembratriene-4,8-diol by oxidative cleavage of the 11,12-double bond with subsequent cyclization to the seco-lactone 14.

Secondary metabolite production by the phytopathogen Alternaria cinerariae has been investigated resulting in the isolation and identification of αβ-dehydrocurvularin and curvularin as products of this fungus. The phytotoxicity of these compounds is demonstrated.

Nine Hoya species were investigated for their leaf flavonoids. Four species contained flavonols identified as the 3-diglycosides of kaempferol and/or isorhamnetin, in some species acylated with ferulic and/or p-cumaric acid. Five species had no flavonols but were rich in flavones. Identified were: schaftoside, isoschaftoside, di-C-arabino-sylapigenin and vicenin 2.

Analysis of human thymus steroids by liquid-gel chro­matography and gas chromatography-mass spectrometry revealed in dependence of age 4-pregnene-3,20-dione, 11β-hydroxy-4-pregnene-3,20-dione, 7β-hydroxycholesterol, and 7-ketocholesterol. 11β-Hydroxy-4-pregnene-3,20-dione should be the inhibitor of immune maturation.

The previously reported interaction between ascorbate monoanion and dehydroascorbic acid yielding semidehy-droascorbic acid has been shown to be therm odynamically unfeasible and non-existent. No evidence for radical formation in the reinvestigation of the reaction using ESR spectroscopy under careful exclusion of air could be found. Our results show that the detection of the free radical in earlier studies resulted from the reaction of ascorbate with traces of oxygen and/or metals.

For the transformation of glutamic acid into α-amino-butyric acid upon irradiation a decarboxylation mechanism involving the formation of CO 2 has been proposed previously. Here we present further experimental evidence in favour of this mechanism. A dditionally the formation of CO as a decarboxylation product has been detected; a radical anion mechanism for its formation is proposed.

The role of the Western Whip snake Coluber viridißavus was demonstrated as a definitive host for Sarcocystis podarcicolubris sp. nov. of the Italian Wall lizard Podarcis sicula and the Tyrrhenian Wall lizard Podarcis tiliquerta. Sporocysts (9.58 x 6.94 μm) of S. podarcicolubris from a naturally infected snake C. viridißavus were fed to a Sarcocystis free lizard P. sicula and via arthropods Musca domestica to another Sarcocystis free lizard P. tiliquerta. About 3-4 months later sarcocysts could be detected in both lizards. The cysts measured 90-130 μm × 450-550 μm. The cyst wall had 2.5-3 μm long villus like protrusions. The sausage-shaped bradyzoites measured circa 7.7 × 2 μm. Refeeding of the experimentally infected lizards to the snake led to a renewed shedding of sporocysts after a prepatency of 12 -15 days.