Einbau von 14C-mevalonsäurelacton in hopfenbitterstoffe

Labeled mevalonate is incorporated into terpenes and hop bitter compounds by Humulus lupulus. The role of mevalonate as a precursor for the prenyl (3-methyl-but-2-enyl) side chain of the hop bitter compounds is discussed.     

Introduction

The only concrete basis for the discontinuous and hierarchical organization of extant organisms lies in their genealogical (i. e. germ line) relationships. Individuals and populations of common descent are called sib or stirps. Ideally, systematic classification is based on the formulas: (1) sib + taxonomic category + name = taxon, and (2) divergent genealogy of sibs + hierarchy of taxonomic categories + names = taxonomic system (Fig. 1).Presented at the symposium Speciation and the Species Concept during the XIIth International Botanical Congress, Leningrad, July 8, 1975.     

Chromosome numbers and differentiation of centrospermous families

The patterns of variation of chromosome numbers in theCentrospermae suggest a common ancestry of centrospermous anthocyanin and betalain families. Phylogenetic divergence in the order may have originated with progenitors similar to extantMolluginaceae, Aizoaceae orPhytolaccaceae taxa with x = 9. Evolutionary radiation and advancement in several lines then seems to have been paralleled by trends for increasing chromosome base numbers through dysploidy and polyploidy, e.g. towardsCaryophyllaceae, Portulacaceae-Basellaceae, Hectorellaceae, Cactaceae, Didieraceae, Nyctaginaceae andChenopodiaceae-Amaranthaceae. Presented in the Symposium Evolution of Centrospermous Families, during the XIIth International Botanical Congress, Leningrad, July 8, 1975.     

Purification and properties of chorismate mutase-prephenate dehydratase and prephenate dehydrogenase from Alcaligenes eutrophus.

Chorismate mutase and prephenate dehydratase from Alcaligenes autophus H16 were purified 470-fold with a yield of 24%. During the course of purification, including chromatography on diethylaminoethyl (DEAE)-cellulose, phenylalanine-substituted Sepharose, Sephadex G-200 and hydrogyapatite, both enzymes appeared in association. The ratio of their specific activities remained almost constant. The molecular weight of chorismate mutase-prephenast dehydratase varied from 144,000 to 187,000 due to the three different determination methods used. Treatment of electrophoretically homogeneous mutase-dehydratase with sodium dodecyl sulfate dissociated the enzyme into a single component of molecular weight 47,000, indicating a tetramer of identical subunits. The isoelectric point of the bifunctional enzyme was 5.8. Prephenate dehydrogenase was not associated with other enzyme activities; it was separated from mutasedehydratase by DEAE-cellulose chromatgraphy. Chromatography on DEAE Sephadex, Sephadex G-200, and hydroxyapatite resulted in a 740-fold purification with a yield of 10%. The molecular weight of the enzyme was 55,000 as determined by sucrose gradient centrifugation and 65,000 as determined by gel filtration or electrophoresis. Its isoelectric point was pH 6.6. In the overall conversion of chorismate to phenylpyruvate, free prephenate was formed which accumulated in the reaction mixture. The dissociation of prephenate allowed prephenate dehydrogenase to compete with prephenate dehydratase for the substrate.     

Cold-induced [Ca2+]cyt elevations function to support osmoregulation in marine diatoms

Diatoms are a group of microalgae that are important primary producers in a range of open ocean, freshwater, and intertidal environments. The latter can experience substantial long- and short-term variability in temperature, from seasonal variations to rapid temperature shifts caused by tidal immersion and emersion. As temperature is a major determinant in the distribution of diatom species, their temperature sensory and response mechanisms likely have important roles in their ecological success. We examined the mechanisms diatoms use to sense rapid changes in temperature, such as those experienced in the intertidal zone. We found that the diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana exhibit a transient cytosolic Ca²⁺ ([Ca²⁺]_cyt) elevation in response to rapid cooling, similar to those observed in plant and animal cells. However, [Ca²⁺]_cyt elevations were not observed in response to rapid warming. The kinetics and magnitude of cold-induced [Ca²⁺]_cyt elevations corresponded with the rate of temperature decrease. We did not find a role for the [Ca²⁺]_cyt elevations in enhancing cold tolerance but showed that cold shock induces a Ca²⁺-dependent K⁺ efflux and reduces mortality of P. tricornutum during a simultaneous hypo-osmotic shock. As intertidal diatom species may routinely encounter simultaneous cold and hypo-osmotic shocks during tidal cycles, we propose that cold-induced Ca²⁺ signaling interacts with osmotic signaling pathways to aid in the regulation of cell volume. Our findings provide insight into the nature of temperature perception in diatoms and highlight that cross-talk between signaling pathways may play an important role in their cellular responses to multiple simultaneous stressors.

A calcium signaling pathway in marine diatoms is activated by cold temperature and enhances survival during simultaneous hypo-osmotic stress.     

Characteristics of the asparagine-linked oligosaccharide from honey-bee venom phospholipase A2. Evidence for the presence of terminal N-acetylglucosamine and fucose in an insect glycoprotein

Eighty-eight % of phospholipase A2 from honey-bee (Apis mellifica) venom is glycosylated. Its single oligosaccharide exists in several structural variants, which represent consecutive stages of the "N-glycan processing pathway". The carbohydrate carries terminal fucosyl and N-acetyl-glucosaminyl residues. This is in contrast to earlier reports which suggest the lack of respective glycosyl-transferases in insects.     

Isolation and characterization of a virulent bacteriophage from Staphylococcus carnosus

Abstract A virulent bacteriophage, øSK311, was isolated from Staphylococcus carnosus , an organism used as a starter culture for the production of dry sausage. Electron microscopic studies revealed that this bacteriophage showed some morphological similarities with the Escherichia coli phages T4 and λ. The host range of øSK311 extends over 9 different staphylococcal species. A phage-resistant mutant of S. carnosus could be isolated. Cells of this mutant exhibited a capsule-like structure. The DNA of øSK311 possesses a G + C content of 31.4 mol% and appears to be highly modified.     

Communities of archaea and bacteria in a subsurface radioactive thermal spring in the Austrian Central Alps, and evidence of ammonia-oxidizing Crenarchaeota

Scanning electron microscopy revealed great morphological diversity in biofilms from several largely unexplored subterranean thermal Alpine springs, which contain radium 226 and radon 222. A culture-independent molecular analysis of microbial communities on rocks and in the water of one spring, the "Franz-Josef-Quelle" in Bad Gastein, Austria, was performed. Four hundred fifteen clones were analyzed. One hundred thirty-two sequences were affiliated with 14 bacterial operational taxonomic units (OTUs) and 283 with four archaeal OTUs. Rarefaction analysis indicated a high diversity of bacterial sequences, while archaeal sequences were less diverse. The majority of the cloned archaeal 16S rRNA gene sequences belonged to the soil-freshwater-subsurface (1.1b) crenarchaeotic group; other representatives belonged to the freshwater-wastewater-soil (1.3b) group, except one clone, which was related to a group of uncultivated Euryarchaeota. These findings support recent reports that Crenarchaeota are not restricted to high-temperature environments. Most of the bacterial sequences were related to the Proteobacteria (alpha, beta, gamma, and delta), Bacteroidetes, and Planctomycetes. One OTU was allied with Nitrospina sp. (delta-Proteobacteria) and three others grouped with Nitrospira. Statistical analyses suggested high diversity based on 16S rRNA gene analyses; the rarefaction plot of archaeal clones showed a plateau. Since Crenarchaeota have been implicated recently in the nitrogen cycle, the spring environment was probed for the presence of the ammonia monooxygenase subunit A (amoA) gene. Sequences were obtained which were related to crenarchaeotic amoA genes from marine and soil habitats. The data suggested that nitrification processes are occurring in the subterranean environment and that ammonia may possibly be an energy source for the resident communities.     

Synthesis of full length PB1-F2 influenza A virus proteins from 'Spanish flu' and 'bird flu'.

The proapoptotic influenza A virus PB1-F2 protein contributes to viral pathogenicity and is present in most human and avian isolates. Previous synthetic protocols have been improved to provide a synthetic full length H1N1 type PB1-F2 protein that is encoded by the 'Spanish flu' isolate and an equivalent protein from an avian host that is representative of a highly pathogenic H5N1 'bird flu' isolate, termed SF2 and BF2, respectively. Full length SF2, different mutants of BF2 and a number of fragments of these peptides have been synthesized by either the standard solid-phase peptide synthesis method or by native chemical ligation of unprotected N- and C-terminal peptide fragments. For SF2 chemical ligation made use of the histidine and the cysteine residues located in positions 41 and 42 of the native sequence, respectively, to afford a highly efficient synthesis of SF2 compared to the standard SPPS elongation method. By-product formation at the aspartic acid residue in position 23 was prevented by specific modifications of the SPPS protocol. As the native sequence of BF2 does not contain a cysteine residue two different mutants of BF2 (Y42C) and BF2 (S47C) with appropriate cysteine exchanges were produced. In addition to the full length molecules, fragments of the native sequences were synthesized for comparison of their physical characteristics with those from the H1N1 human isolate A/Puerto Rico/8/34 (H1N1). All peptides were analyzed by mass spectrometry, (1)H NMR spectroscopy, and SDS-PAGE. The protocols allow the synthesis of significant amounts of PB1-F2 and its related peptides. Copyright (c) 2008 European Peptide Society and John Wiley & Sons, Ltd.