Nina Springer

Abstract: User comments allow ‘annotative reporting’ by embedding users’ viewpoints within an article's context, providing readers with additional information to form opinions, which can potentially enhance deliberative processes. But are these the only reasons why people comment on online news and read these comments? This study examines factors that motivate, or demotivate and constrict, such participation by surveying nearly 650 commenters, lurkers, and non-users in Germany. From a normative perspective, the results are ambivalent. The results show that commenters are driven by social-interactive motives to participate in journalism, and to discuss with other users. However, the data suggest that commenters do not obtain cognitive gratifications to the desired extent. Presumably, their exchange is socially and not deliberatively motivated. Reading comments is fuelled by both cognitive and entertainment motives, but regression analyses show that the entertainment dimension − a dimension that is not usually consid...

Abstract: Summary The isolation of a halotolerant, Fe(III)-reducing, Gram-negative bacterium from surface sediments of the Sippewisset marsh in Woodshole (USA) will be described. Detailed molecular taxonomic studies such as comparative 16S rRNA sequence analysis and DNA-DNA hybridization experiments revealed that the newly isolated strain is closely related to the previously isolated strain BrY. Both strains belong to the DNA-DNA similarity group IV of Shewanella putrefaciens which has recently been described as Shewanella alga . Thus, the ability to reduce Fe(III) is no longer restricted to S. putrefaciens within the genus but is also found among strains of S. alga . A 16S rRNA targeted probe has been designed that enabled us to rapidly differentiate strains of S. alga from those of S. putrefaciens and other bacteria.

Abstract: Summary 23S rRNA genes of 17 strains representing the α, s, γ, δ and µ subclasses of the Proteobacteria were completely sequenced. The sequences were aligned to about 120 published as well as unpublished complete or almost complete primary structures of 23S rRNAs from other members of the domain Bacteria representing all known phyla. Primary and higher order structure analyses revealed remarkable differences of predicted 23S rRNA structures from members of the different subclasses. A phylogenetic tree reflecting the relationships among proteobacteria was reconstructed based on 23S rRNA sequence comparison. The topology of the tree is similar to that of a tree based on an equivalent 16S rRNA sequence data set.

Abstract: New species names, Brachybacterium alimentarium and Brachybacterium tyrofermentans, are proposed for two coryneform bacteria isolated from the surfaces of Gruyere and Beaufort cheeses. These two species are similar in their biochemical and chemotaxonomic characteristics but distinct from previously described bacteria. The most distinctive characteristics are the presence of meso-diaminopimelic acid-containing peptidoglycan with a D-GIU-D-ASP interpeptide bridge and the presence of erythritol teichoic acids that contain diaminoglucuronic acid (an uncommon substituent). The menaquinone pattern of these organisms is unique among coryneform bacteria. DNA-DNA hybridization experiments revealed that the level of hybridization between the two organisms is 15%, which indicates that they are distinct species. Despite the unique biochemical characteristics of these bacteria, a 16S rRNA sequence comparison revealed that they are unquestionably related to Brachybacterium faecium, Brachybacterium nesterenkovii, and Brachybacterium conglomeratum. DNA-DNA hybridization experiments performed with these three species, B. alimentarium, and B. tyrofermentans revealed that the levels of complementarity ranged from 11 to 38%, values that are similar to the values obtained for Brachybacterium strains described previously. With the inclusion of B. alimentarium and B. tyrofermentans the genus Brachybacterium becomes somewhat heterogeneous with respect to chemotaxonomic characteristics.

Abstract: In-depth interviews with 75 female journalists who work or have worked in Germany, India, Taiwan, the United Kingdom, and the United States of America reveal that they face rampant online gendered ...

Abstract: Originally published in Contemporary Psychology: APA Review of Books, 1994, Vol 39(2), 225. Reviews the book, The Nature and Origins of Mass Opinion by John Zaller (1992). The author's commendable effort to specify a model of mass opinion formation offers readers an introduction to the prevailing vi

Abstract: Fatty acids and alcohols are key intermediates in the methanogenic degradation of organic matter, e.g., in anaerobic sewage sludge digestors or freshwater lake sediments. They are produced by classical fermenting bacteria for disposal of electrons derived in simultaneous substrate oxidations. Methanogenic bacteria can degrade primarily only one-carbon compounds. Therefore, acetate, propionate, ethanol, and their higher homologs have to be fermented further to one-carbon compounds. These fermentations are called secondary or syntrophic fermentations. They are endergonic processes under standard conditions and depend on intimate coupling with methanogenesis. The energetic situation of the prokaryotes cooperating in these processes is problematic: the free energy available in the reactions for total conversion of substrate to methane attributes to each partner amounts of energy in the range of the minimum biochemically convertible energy, i.e., 20 to 25 kJ per mol per reaction. This amount corresponds to one-third of an ATP unit and is equivalent to the energy required for a monovalent ion to cross the charged cytoplasmic membrane. Recent studies have revealed that syntrophically fermenting bacteria synthesize ATP by substrate-level phosphorylation and reinvest part of the ATP-bound energy into reversed electron transport processes, to release the electrons at a redox level accessible by the partner bacteria and to balance their energy budget. These findings allow us to understand the energy economy of these bacteria on the basis of concepts derived from the bioenergetics of other microorganisms.

Abstract: Production and consumption processes in soils contribute to the global cycles of many trace gases (CH4, CO, OCS, H2, N2O, and NO) that are relevant for atmospheric chemistry and climate. Soil microbial processes contribute substantially to the budgets of atmospheric trace gases. The flux of trace gases between soil and atmosphere is usually the result of simultaneously operating production and consumption processes in soil: The relevant processes are not yet proven with absolute certainty, but the following are likely for trace gas consumption: H2 oxidation by abiontic soil enzymes; CO cooxidation by the ammonium monooxygenase of nitrifying bacteria; CH4 oxidation by unknown methanotrophic bacteria that utilize CH4 for growth; OCS hydrolysis by bacteria containing carbonic anhydrase; N2O reduction to N2 by denitrifying bacteria; NO consumption by either reduction to N2O in denitrifiers or oxidation to nitrate in heterotrophic bacteria. Wetland soils, in contrast to upland soils are generally anoxic and thus support the production of trace gases (H2, CO, CH4, N2O, and NO) by anaerobic bacteria such as fermenters, methanogens, acetogens, sulfate reducers, and denitrifiers. Methane is the dominant gaseous product of anaerobic degradation of organic matter and is released into the atmosphere, whereas the other trace gases are only intermediates, which are mostly cycled within the anoxic habitat. A significant percentage of the produced methane is oxidized by methanotrophic bacteria at anoxic-oxic interfaces such as the soil surface and the root surface of aquatic plants that serve as conduits for O2 transport into and CH4 transport out of the wetland soils. The dominant production processes in upland soils are different from those in wetland soils and include H2 production by biological N2 fixation, CO production by chemical decomposition of soil organic matter, and NO and N2O production by nitrification and denitrification. The processes responsible for CH4 production in upland soils are completely unclear, as are the OCS production processes in general. A problem for future research is the attribution of trace gas metabolic processes not only to functional groups of microorganisms but also to particular taxa. Thus, it is completely unclear how important microbial diversity is for the control of trace gas flux at the ecosystem level. However, different microbial communities may be part of the reason for differences in trace gas metabolism, e.g., effects of nitrogen fertilizers on CH4 uptake by soil; decrease of CH4 production with decreasing temperature; or different rates and modes of NO and N2O production in different soils and under different conditions.

Abstract: A new hierarchic classification structure for the taxa between the taxonomic levels of genus and class is Proposed for the actinomycete line of descent as defined by analysis of small subunit (16S) rRNA and genes coding for this molecule (rDNA). While the traditional circumscription of a genus of the actinomycete subphylum is by and large in accord with the 16S rRNA/rDNA-based phylogenetic clustering of these organisms. most of the higher taxa proposed in the past do not take into account the phylogenetic clustering of genera. The rich chemical, morphological and physiological diversity of phylogenetically closely related genera makes the description of families and higher taxa so broad that they become meaningless for the description of the enclosed taxa. Here we present a classification system in which phylogenetically neighboring taxa at the genus level are clustered into families, suborders, orders, subclasses, and a class irrespective of those phenotypec characteristics on which the delineation of taxa has been based in the past. Rather than being based on a listing of a wide array of chemotaxonomic, morphological, and physiological properties, the delineation is based solely on 16S rDNA/rRNA sequence-based phylogenetic clustering and the presence of taxon-specific 16S rDNA RNA signature nucleotides.