Band 47, Heft 11-12

Hypothallin, a metabolite of the lichen Schismatomma hypothallinum (Lecanactidaceae, Opegraphales) has been structurally elucidated as (-)-N-benzoyl-ʟ-phenylalaninyl-N′- benzoyl-ʟ-leucinate by NMR and MS and by synthesisᴅ

The new iridoid genistifolin and the known antirrinoside and linarioside have been isolated from aerial parts of Linaria genistifolia (Scrophulariaceae). TLC data indicate the presence of 6-deacetylgenistifolin

Many samples of Monoclea gottschei from Central and South America and the Caribbean Islands have been compared for their flavonoids. The species exhibits the most diverse flavonoid pattern ever observed for a liverwort. From different chemotypes 28 flavones were isolated: 8 aglycones, 3 monoglycosides, 9 diglycosides, 6 triglycosides and 2 oligo- or polyglycosides. The chromatographic and spectroscopic data of previously unidentified compounds are presented. Samples of M . forsteri from New Zealand have been analyzed for flavonoids too, but their flavone patterns are much less diverse: 1 aglycone, 1 polyglycoside and 2 further mono-or-diglycosides were isolated. The differences in flavonoid production of both species are an additional feature for the distinction of the two Monoclea species

The epicuticular leaf waxes of Quercus robur were analyzed continuously over a two years vegetation period with preparation every week from April to November. The folded leaflets in buds have waxes quite different in yield and composition from those of mature leaves. They contain homologous series of hydrocarbons, wax esters, primary alcohols, fatty acids and triterpenoids from the beginning, but not aldehydes. After leaf unfolding a dynamic biosynthesis of alcohols, aldehydes and fatty acids is observed in May and June. Wax content is doubled per dry weight or in cm 2 leaf surface area and 80-fold per one leaf in that time. During leaf development tetracosanol becomes the dominant epicuticular wax component comprising ca. 40% of the wax. In both years of the study a reactivation of wax ester biosynthesis is observed in October and November. Esters with chain length C 36 and C 38 increased particularly. From July to November the wax composition remained nearly constant within mean values and their standard deviations. Within the two years studied most values concerning wax composition are reproducible and are therefore genetically determined. In spring the growing processes are influenced by climatic factors

Already the very young leaflets of oak (Quercus robur L.), newly emerging from their buds, are covered by a thin wax layer, but at this time it lacks any wax sculptures or crystalloids. Both in its amount and its composition this wax layer is quite different to that of mature leaves. After leaf unfolding a dynamic biosynthesis of wax lipids is started. Ten days after the leaf has emerged from its bud, wax crystalloids are seen for the first time, developing out of the wax layer in the form of platelets. These crystalloids increase in size and quantity within the next weeks and are present on both leaf surfaces. On the adaxial side a dense and uniform arrangement of fringed edged platelets is observed. Similar dense arrangements of platelets are found on the abaxial leaf side, but with an intensive concentration and orientation around the stomata. All platelets are composed of tetracosanol, the main wax component, accounting for more than 40% of wax. Variations in surface wax ultrastructures are observed in July. Well formed platelets and melted away crystalloids are found close together in distinct parts of the same leaf, both on the adaxial and on the abaxial sides of the leaf. These observations pertain to preparations made from July to November with a trend toward recrystallization in October. High temperature and essential oils may be the reasons for the melting away or solution of the platelets

Cell suspension cultures of chickpea (Cicer arietinum L.) were used to prepare protoplasts and vacuoles. The vacuolar preparation revealed only slight contaminations of cytoplasmic marker enzymes. HPLC analysis of the vacuolar extract showed that the malonylglucosides of isoflavones, isoflavanones and pterocarpans are exclusively located in the vacuole. Experiments designed to determine the subcellular localization of the isoflavone malonylglucoside: malonylesterase suggest an association of this enzyme with the vacuolar membrane. Finally, a β-l,3-glucanase and a chitinase with basic isoelectric points were also found to be localized in the chickpea vacuoles

Excised leaves and cell suspension cultures of soybean (Glycine max L.) were incubated with [UL- 14 C]-3,4-dichloroaniline. The compound was almost completely metabolized after 48 h in both systems; it was apparent that the major detoxification pathways present in the excised leaves were also present in the cultured cells. Besides considerable amounts of insoluble residues, the N-glucosyl and the N-malonyl conjugates of 3,4-dichloroaniline, and a yet unknown metabolite was formed in the excised leaves; tentatively the latter was identified with the 6′-O-malonylester of N-glucosyl-3,4-dichloroaniline. The cell suspension cultures produced predominantly the N-malonyl conjugate, besides negligible amounts of the N-glucosyl conjugate, and insoluble residues; the majority of the N-malonyl compound was excreted into the medium. It was shown, that the metabolism of 3,4-dichloroaniline in excised leaves and cell suspension cultures of soybean was directed towards different end products: the excised leaves were able to make extensive use of cell wall structures as a deposit for xenobiotic bound residues, resembling plants in this respect; lack of these structures in the cultured soybean cells resulted in a soluble end product, namely the N-malonyl conjugate

Ceql, a type II restriction endonuclease, an isoschizomer of EcoRV was purified to apparent homogeneity by a combination of salt precipitation, ion exchange, dye affinity and hydrophobic interaction chromatographies. The crude enzyme was present in the form of large aggregates that could be pelleted by high speed centrifugation. The enzyme was not associated with cellular membranes, though non-ionic detergents lowered the apparent size of the aggregates. The purified enzyme also showed a tendency to form large molecular mass (66-600 kDa) complexes under physiological conditions, in the absence of cleavable DNA. The enzyme formed smaller complexes in the presence of DNA and non-ionic detergents and dissociated into subunits (and undergoes reversible loss of activity) in the presence of high concentrations of salts. According to SDS gel electrophoresis and sedimentation analysis the molecular mass of the monomer 32 ± 2 kDa. The enzyme had a rather broad pH optimum, extending into the alkaline range and lost specificity and activity in buffers below pH 6

Both, Haloferax mediterranei and Haloferax volcanii membranes contain ATPases which are capable of hydrolyzing ATP in presence of Mg 2+ or Mn 2+ . The ATPases require high concentrations of NaCl, a pH value of 9, and high temperatures up to 60 °C. Free manganese ions inhibited the enzyme activity of either ATPase. The ATPases of Hf. mediterranei and Hf. volcanii, respectively, show different sensitivities to inhibitors of ATP hydrolysis. ATP hydrolysis of isolated Hf. mediterranei ATPase was inhibited by NaN 3 , which was reported to be specific for F-ATPases, by nitrate and N-ethylmaleimide (NEM), which are specific inhibitors of V-ATPases. ATP hydrolysis of Haloferax mediterranei membranes was not inhibited by DCCD , but [ 14 C]DCCD was bound to a 14 kDa peptide of the isolated, partially purified enzyme. Furthermore, the ATPase was inactivated by preincubation with 7-chloro-4-nitrobenzofurazan (NBD-Cl). The ATPase activity of Hf. volcanii membranes was inhibited by NEM but not by nitrate and NaN 3 . SDS gel electrophoresis of the partially purified enzyme of Haloferax mediterranei showed putative ATPase subunits of 53.5, 49, 42, 22, 21, 14, 12, and 7.5 kDa. Immunoblots showed cross reactivity between a 53 kDa peptide and anti-β (chloroplast F 1 ), as well as between 53, 50 and 47 kDa peptides and an ATPase antibody of Methanosarcina barkeri. The results will be discussed in context with the placement of the archaebacterial ATPases (A-ATPases) between F- and V-ATPases

The plant acetyl-CoA synthetase (ACS) is bound to the plastids and provides acetyl-CoA, the starting substrate for de novo fatty acid biosynthesis in plastids. This enzymic reaction, which consumes ATP and releases AMP, can be inhibited by different alkyladenylates such as ethyl-, isopropyl-, propyl- or allyl-adenylates as is shown here. The inhibition mechanism is competitive with respect to ATP and non-com petitive with respect to acetate. I 50 -values and the inhibition constants K( (ATP), K i (acetate) and K ii (acetate) are given. The results suggest that, also in plants, acetyl-adenylate is the endogenous intermediate in the enzymic formation of acetyl-CoA from acetate by acetyl-CoA synthetase

In order to produce the important flavour compound sinensal microbial ω-hydroxylation of farnesene and its sulfone derivative were investigated. While farnesene proved to be a poor substrate, its sulfone could be hydroxylated to the ω-hydroxyfamesene sulfones in up to 27% yield. Some strains could discriminate between the E- and Z-configurated substrate. In low yields products hycroxylated at different positions and two monocyclofarnesane derivatives could also be isolated

An L-amino acid oxidase with high specifity for basic L-amino acids was isolated from the cyanobacterium Synechococcus PCC 7942, and the enzyme was partially characterized. This enzyme was compared to the previously described L-amino acid oxidase from Synechococcus PCC6301 (G. Wälzlein, A. E. Gau, and E. K. Pistorius, Z. Naturforsch. 43c, 5 4 5-553, 1988). In addition, photosystem II complexes were isolated from Synechococcus PCC 7942, and it could be shown that a 36 kDa polypeptide which crossreacts with the antiserum raised against the L-amino acid oxidase (50 kD a) is present in isolated PS II complexes from Synechococcus PCC 7942 as already shown to be the case for Synechococcus PC C 6301 (A. E. Gau, G. W älzlein, S. Gärtner, M. Kuhlmann, S. Specht, and E. K. Pistorius, Z. Naturforsch. 44c, 9 7 1 -9 7 5 , 1989). These results clearly show that in isolated photosystem II complexes from Synechococcus PCC 6301 as well as PCC 7942 a fourth polypeptide (besides D 1, D 2 and the manganese stabilizing protein) is present in the 30 kDa region and support our hypothesis suggesting that the water oxidizing enzyme is a separate protein (distinct from D 1 and D 2)

A 36 kDa polypeptide which previously was shown to be present in purified photosystem II complexes from Synechococcus PCC 6301 and which crossreacts with the antiserum raised against the soluble L-amino acid oxidase of 50 kDa from Synechococcus PCC 6301 (A. E. Gau, G. Wälzlein, S. Gärtner, M. Kuhlmann, and E. K. Pistorius, Z. Naturforsch. 44c, 971, 1989), was isolated from thylakoid membranes of the same cyanobacterium grown under mild iron deficiency. This peptide is present in about equal amounts in thylakoid membranes of Synechococcus PCC 6301 grown under regular or iron deficient conditions. The antiserum raised against this thylakoid membrane bound 36 kDa peptide crossreacts with the soluble L-amino acid oxidase of 50 kDa. These results further support our conclusion that the thylakoid membrane bound 36 kDa polypeptide is a modified form of the soluble 50 kDa L-amino acid oxidase. In addition, a 34 kD a polypeptide was isolated from iron stressed thylakoid membranes, and an antiserum was also raised against this protein. Immunoblot experiments with this antiserum show that the 34 kDa peptide is present in elevated amounts in thylakoid membranes from Synechococcus cells grown under iron deficiency and that it is alm ost absent in thylakoid membranes from cells grown under regular conditions

Characteristics of thermoluminescence (TL) glow curves were studied in thylakoids isolated from pea leaves after an exposure to very high light in the TL device. The inhibition of photosynthesis was detected both as decreases of oxygen evolution rates and of variable fluorescence. In another more classical experiment, leaves were exposed to high light at low temperature (5 °C) for 4 h and recovery of normal PS II characteristics were followed during a 20 h time period under low light at 20 °C. TL study was performed on thylakoids isolated from these leaves. Charging of bands was performed by an illumination at low temperature ( - 8 0 °C). Illumination at low temperature ( - 8 0 °C) induces 2 types of TL bands called Z variable (Z v ) band peaking at about -70 °C and a classical B band peaking at 35 °C. B band is ascribed to recombination in pairs S 2/3 Q B - , whereas the origin of Z v bands remains unclear. Modified Z v bands, with flat shape and presenting a large part resistant to ethanol, were evidenced after some minutes of dark adaptation, both in light-exposed thylakoids and in thylakoids isolated from photoinhibited leaves. This ethanol resistant part in Z v band was only induced by photoinhibitory treatment performed under aerobic conditions (21% O 2 in media), both in vitro and in vivo; thus, the appearance of the special Z v band would be related to an oxidative process accompanying photoinhibition. B bands presented reduced sizes and a shift of peak maximum of about 5 °C after some minutes of dark adaptation. In vivo, the recovery of a high PS II activity and of B bands displaying normal characteristics occurs parallely to reappearance of Z v bands with normal shape and with a vestigial ethanol resistant band

Mass spectrometric analysis shows that blue light enhances oxygen uptake during photosynthesis in Chlorella fusca. Assays in which all of the normal 16 O 2 of air has been substituted by 18 O 2 permit discrimination between photosynthetic O 2 -evolution (measured as 16 O 2 , i.e. mass 32) and O 2 -uptake (measured as 18 O 2 , i.e. mass 36). A chlorophyll-free Chlorella kessleri mutant for which in earlier studies the occurrence of blue light enhanced oxidative carbohydrate degradation has been demonstrated (W. Kowallik, H. Gaffron, Planta 69, 9 2 -9 5 (1966); W. Kowallik, Ann. Rev. Plant Physiol. 33, 5 7 -7 2 (1982)) has been used for comparison in the present study. The light intensity dependencies of the observed effect seem to differ in mutant and wild type cells. In the mutant a fluence rate of 1 .5 -2 .0 (μE m -2 ·s -1 of blue light yields saturation, whereas in the wild type even ten times this value does not. A wavelength dependence of the effect measured with equal fluence rates at 422 nm, 457 nm, 488 nm, 555 nm and 649 nm shows maximal efficiency around 460 nm and no significant effect of red light. This agrees with earlier studies on the chlorophyll- free mutant. As a result of this correspondence, we think that the enhanced oxygen uptake during photosynthesis concerns oxidative carbohydrate degradation. The putative mechanism and significance of the observed blue light enhanced respiration in photosynthesizing Chlorella are discussed

The effect of 14 flavones on luminol-dependent chemiluminescence of neutrophils was studied in vitro. Chemiluminescence was used in this study as an indicator for the production of a reactive oxygen species by neutrophils, stimulated by phorbol myristate acetate. While flavone- 8-acetic acid, and most of the compounds tested, inhibited chemiluminescence, flavone and its 5-hydroxy-7-methoxy derivatives enhanced it by up to 150%. The most active inhibitors of photon emission were the glycosides. These results indicate that lipophilicity and some structural determinants modulate the chemiluminescent capacity of neutrophils

Two enzymes participating in 2′-deoxyadenosine (dAdo) metabolism: dAdo kinase (dAdoK EC 2.7.1.76) and adenosine deaminase (ADA, EC 3.5.4.4) were partially purified from rat liver mitochondria and cytosol and influence of nucleosides and nucleotides on the activity of these enzymes were investigated. Mitochondrial and cytosol dAdoK are separate proteins, while ADA from both subcellular fractions possesses similar physical properties. dGTP, a com petitive inhibitor of mitochondrial dAdoK, inhibits cytosol ADA in a mixed way but activates mitochondrial ADA and cytosol dAdoK. A possible effect of dGTP on dAdo metabolism in mitochondria and cytosol is discussed

Infection experiments using tomato (Lycopersicon esculentum cv. Moneymaker) plants and three strains of Clavibacter michiganense subsp. michiganense were conducted. The bacterial isolates differed in plasmid status, virulence (measured as wilting index and as reduction of plant biomass) and the ability to colonize the plants. Differences in the expression of exopolysaccharides and the exoenzymes endocellulase, polygalacturonase, and xylanase, respectively, were not found with the bacterial isolates. As infection-induced responses of the plants timedepending increases in soluble phenolic material, including chlorogenic acid and rutin, in the steroid alkaloid tomatine and in cell wall-bound cinnamic acids were found. In the latter fraction p-coumaric, ferulic and especially caffeic acid were the main constituents. All plant responses were preferentially expressed in the compatible interaction. Sesquiterpenoid phytoalexins were not found in the infected plant tissues. The relation between bacterial pathogenicity and plant responses is discussed

After electrophoresis in DNA -containing polyacrylamide gels, two acid DNase activities can be detected in peripheral, mononuclear cells of the human blood. One of these acid DNase activities correlates with cell proliferation; its isoelectrical point is at pI 7.4. By means of this DNase activity, a quantity of less than 1% leukemic cells can be detected. The increased acid DNase activity can indicate the proliferation of malignant cell populations and possibly the proliferation of cell populations during immunological reactions

We have tested the action of three agents microinjected into the ventral nerve photoreceptor of Limulus on the electrical response to dim light. 1. A monoclonal antibody (mAb 4 A) against the G ɑ subunit of frog transducin reduces the size of the receptor current to 60%, suggesting an interaction with G ɑ in the Limulus photoreceptor. 2. Injection of Clostridium botulinum ADPribosyltransferase C 3 reduces the size to 46%; latency is not affected. The results imply that small GTP-binding proteins play a functional role in photoreception of invertebrates. 3. Injection of GD P-β-S reduces dose-dependently the size of the receptor current to 15% and prolongs the latency to 200%, presumably by reducing number and rate of G-protein activations

In addition to several previously reported flavonoid aglycones, the white farinose material accumulating on the lower leaf surface of Notholaena grayi contains as major constituent a triterpene. This product has now been identified by detailed NMR spectroscopic studies as the novel (24R)-3ɑ, 24,25-trihydroxylanost-9(11)- en-28-oic acid

A circadian rhythm of leaf movements of Arabidopsis thaliana and its recording in continuous weak light with a video-computer system is described

Ehrlich cell plasma membrane vesicles have a ferricyanide reductase activity that shows two phases. These two phases were kinetically characterized. Evidence is presented for a differential effect of trypsin on both phases

The elementary responses, the “bumps”, of the ventral photoreceptor of Limulus polyphemus were studied under voltage clamp conditions. We compared spontaneous bumps with those induced by light and we applied the G-protein activator A1F 4 - . The amplitude of the spontaneous bumps is on the average 7 - 8 times smaller than that of the light-induced bumps. Bumps induced by A1F 4 - have identical size and time parameters when compared with spontaneous bumps. Thus at least a large part of the spontaneous bumps is probably triggered by the activation of single G-protein molecules. However, if the next step of the transduction chain is gainless, it is also possible the spontaneous bump originate from this step. The different size of spontaneous and light-induced bumps can be explained assuming that a light-activated metarhodopsin molecule leads to the activation of 3 to 12 G-protein molecules