Synthesis of novel 4- and 5-substituted benzyl ether derivatives of vesamicol and in vitro evaluation of their binding properties to the vesicular acetylcholine transporter site

Detection of the central cholinergic deficits, a consistent feature of Alzheimer's disease, is essential to allow preventive measures and/or symptomatic treatment already at a very early stage of the disease. The vesicular acetylcholine transporter (VAChT) represents an appropriate target to establish PET radiotracer that are adequate for brain imaging the loss of cholinergic terminals. Here we describe the synthesis and binding characteristics of novel derivatives of vesamicol, known to represent a specific antagonist of VAChT sites. Novel benzyl ether derivatives of vesamicol either 4- or 5-substituted at the cyclohexylring have been synthesized by different regioselective ring opening reactions of a same epoxide precursor. The affinity and selectivity of the novel compounds to VAChT sites were analyzed by competitive radioligand binding studies in rat brain and liver membrane preparations using tritium labeled radioligands. The 4-substituted fluorobenzylether of vesamicol 10b was shown to exhibit a high affinity to VAChT sites (K(i)-value(10b)=10.7+/-1.7 nM), but demonstrated also binding capacities to sigma receptors (K(i-)value(10b)=18.5+/-6.9 nM, [(3)H]DTG; K(i)-value(10b)=30.6+/-9.6 nM, [(3)H]haloperidol). The data suggest the potential of vesamicol derivatives to design appropriate radiotracer for PET imaging of central cholinergic deficits.     

Identification of clinically relevant protein targets in prostate cancer with 2D-DIGE coupled mass spectrometry and systems biology network platform

Prostate cancer (PCa) is the most common type of cancer found in men and among the leading causes of cancer death in the western world. In the present study, we compared the individual protein expression patterns from histologically characterized PCa and the surrounding benign tissue obtained by manual micro dissection using highly sensitive two-dimensional differential gel electrophoresis (2D-DIGE) coupled with mass spectrometry. Proteomic data revealed 118 protein spots to be differentially expressed in cancer (n = 24) compared to benign (n = 21) prostate tissue. These spots were analysed by MALDI-TOF-MS/MS and 79 different proteins were identified. Using principal component analysis we could clearly separate tumor and normal tissue and two distinct tumor groups based on the protein expression pattern. By using a systems biology approach, we could map many of these proteins both into major pathways involved in PCa progression as well as into a group of potential diagnostic and/or prognostic markers. Due to complexity of the highly interconnected shortest pathway network, the functional sub networks revealed some of the potential candidate biomarker proteins for further validation. By using a systems biology approach, our study revealed novel proteins and molecular networks with altered expression in PCa. Further functional validation of individual proteins is ongoing and might provide new insights in PCa progression potentially leading to the design of novel diagnostic and therapeutic strategies.     

Complement resistance of Borrelia burgdorferi correlates with the expression of BbCRASP-1, a novel linear plasmid-encoded surface protein that interacts with human factor H and FHL-1 and is unrelated to Erp proteins

The etiologic agent of Lyme disease, Borrelia burgdorferi, is capable of circumventing the immune defense of a variety of potential vertebrate hosts. Previous work has shown that interaction of host-derived complement regulators, factor H and factor H-like protein 1 (FHL-1), with up to five complement regulator-acquiring surface proteins (CRASPs) expressed by resistant B. burgdorferi sensu lato isolates conferred complement resistance. In addition expression of CRASP-1 is directly correlated with complement resistance of Borrelia species. This work describes the functional characterization of BbCRASP-1 as the dominant factor H and FHL-1-binding protein of B. burgdorferi. The corresponding gene, zs7.a68, is located on the linear plasmid lp54 and is different from factor H-binding Erp proteins that are encoded by genes localized on circular plasmids (cp32). Deletion mutants of BbCRASP-1 were generated, and a high affinity binding site for factor H and FHL-1 was mapped to the C terminus of BbCRASP-1. Similarly, the predominant binding site of factor H and FHL-1 was localized to the short consensus repeat 7. Factor H and FHL-1 maintain their cofactor activity for factor I-mediated C3b inactivation when bound to BbCRASP-1, and factor H is up to 6-fold more efficient in mediating C3b conversion than FHL-1. In conclusion, BbCRASP-1 (i). binds the host complement regulators factor H and FHL-1 with high affinity, (ii). is the key molecule of the complement resistance of spirochetes, and (iii). is distinct from the Erp protein family. Thus, BbCRASP-1 most likely contributes to persistence of B. burgdorferi and to pathogenesis of Lyme disease.     

Age-specific patterns in honeydew production and honeydew composition in the aphid Metopeurum fuscoviride: implications for ant-attendance

The intensity of the mutualistic relationship between aphids and ants depends mainly on the composition and amount of honeydew. We used the model system Tanacetum vulgare-Metopeurum fuscoviride to study age-related differences in honeydew production and composition and its effect on the mutualism between M. fuscoviride and the ant Lasius niger. First and second instar larvae of M. fuscoviride produced only half of the amount of honeydew as older larvae or adults. There were, however, no differences between age classes in the total honeydew sugar concentration, which averaged approx. 80 μg sugar/μl honeydew. Honeydew sugar composition also did not differ between age classes, and melezitose was the dominant sugar (59% in all classes). The amino acid concentration, by contrast, increased significantly with aphid age, reaching 22.6 nmol per μl honeydew in adult M. fuscoviride. This increase was mainly caused by asparagine and glutamine, while there were no differences in the concentrations of the five other regularly detected amino acids and cystine, respectively. The intensity of ant-attendance was significantly lower in colonies of first and second instar larvae than in colonies of older age classes. Ant-attendance correlated with the amount of honeydew produced, and not with the total amino acid concentration.     

Apoplastic Solute Concentrations of Organic Acids and Mineral Nutrients in the Leaves of Several Fagaceae

Ion chromatographic methods determined organic acids and mainnutrient minerals in the apoplastic solution from leaves ofseveral Fagaceae (Quercus ilex L., Quercus cerris L., Quercusvirgiliana (Ten.) Ten, and Fagus sylvatica L.). The anions oforganic acids found in high amounts (250 to 650 µM) werequinate, malate, and oxalate. Lactate, pyruvate, formate andacetate were detected in relatively low amounts with concentrationsbetween 20 and 200 µM. The total concentration of organicacids in the apoplastic sap ranged between 1.5 and 2 mM. Thetotal concentration of inorganic cations (K⁺, Mg²⁺, NH₄⁺, Ca²⁺,Na⁺) and anions (C1^–, NO₃^–, SO^2–₄ and PO^3–₄)in the apoplastic sap varied between 5 and 10 mM, and 0.35 and1.8 mM, respectively. We conclude that the concentration oforganic acid ions in the leaf apoplast depends mainly on theexchange with the leaf cells and is influenced by the electrochemicalgradient between the symplast and the apoplast in relation tothe water potential of the leaf. The determination of formateand acetate in the apoplastic compartment of leaves lend weightto the argument that the production of these acids by treesis a important emission source to the atmosphere. (Received June 9, 1998; Accepted April 8, 1999)     

UDP-glucose:digitoxin 16′-O-glucosyltransferase from suspension-cultured Digitalis lanata cells

Suspension cultures from several cell lines of Digitalis lanata, as well as cultures from 6 other plant species were checked for their ability to form purpurea-glycoside A from digitoxin. An in-vitro assay for the UDP-glucose:digitoxin 16-O-glucosyltransferase (DGT, EC 2.4.1.-) has been established based on an HPLC method. The enzyme is located in the soluble fraction. Its pH optimum is at 7.4. No enzyme activity was found in either purified vacuole preparations or lysed vacuoles. Ascorbate (10 mM) increased the transferase activity about 4-fold. Of the sugar nucleotides tested, only UDP-glucose served as a glucosyl donor. Digitoxin, digoxin, -acetyldigitoxin, and -acetyldigoxin are substrates for the glucosyltransferase. The role of the DGT during the biotransformation of cardenolides in Digitalis lanata cell suspension cultures is discussed.Abbreviation DGT UDP-glucose:digitoxin 16-C-glucosyltransferase     

A proteomic approach for studying insect phylogeny: CAPA peptides of ancient insect taxa (Dictyoptera, Blattoptera) as a test case

Background  

Neuropeptide ligands have to fit exactly into their respective receptors and thus the evolution of the coding regions of their genes is constrained and may be strongly conserved. As such, they may be suitable for the reconstruction of phylogenetic relationships within higher taxa. CAPA peptides of major lineages of cockroaches (Blaberidae, Blattellidae, Blattidae, Polyphagidae, Cryptocercidae) and of the termite Mastotermes darwiniensis were chosen to test the above hypothesis. The phylogenetic relationships within various groups of the taxon Dictyoptera (praying mantids, termites and cockroaches) are still highly disputed.