1,721,008 research outputs found
VOC emission of various Serratia species and isolates and genome analysis of Serratia plymuthica 4Rx13
No full textBacteria emit a wealth of volatile organic compounds. Gas chromatography coupled to mass spectrometry analysis of five Serratia strains revealed ketones, dimethyl di- and trisulfide and 2-phenylethanol commonly released in this genus. The polymethylated bicyclic hydrocarbon sodorifen was uniquely released by the rhizobacterium Serratia plymuthica 4Rx13. Of 10 Serratia strains, only S.plymuthica isolates originating from plants grown on fields near Rostock (Germany) released this new and unusual compound. Since the biosynthetic pathway of sodorifen was unknown, the genome sequence of S.plymuthica 4Rx13 was determined and annotated. Genome comparison of S.plymuthica 4Rx13 with sodorifen non-producing Serratia species highlighted 246 unique candidate open reading frames.DF
A terpene synthase is involved in the synthesis of the volatile organic compound sodorifen of Serratia plymuthica 4Rx13
No full textBacteria release a plethora of volatile organic compounds (VOCs), including compounds with extraordinary structures. Sodorifen (IUPAC name: 1,2,4,5,6,7,8-heptamethyl-3-methylenebicyclo[3.2.1]oct-6-ene) is a recently identified and unusual volatile hydrocarbon that is emitted by the rhizobacterium Serratia plymuthica 4Rx13. Sodorifen comprises a bicyclic ring structure solely consisting of carbon and hydrogen atoms, where every carbon atom of the skeleton is substituted with either a methyl or a methylene group. This unusual feature of sodorifen made a prediction of its biosynthetic origin very difficult and so far its biosynthesis was unknown. To unravel the biosynthetic pathway we performed genome and transcriptome analyses to identify candidate genes. One knockout mutant (SOD_c20750) showed the desired negative sodorifen phenotype. Here it was shown for the first time that this gene is indispensable for the synthesis of sodorifen and strongly supports the hypothesis that sodorifen descends from the terpene metabolism. SOD_c20750 is the first bacterial terpene cyclase isolated from Serratia spp. and Enterobacteriales. Homology modeling revealed a 3D structure, which indicated a functional role of amino acids for intermediate cation stabilization (W325) and putative proton acceptance (Y331). Moreover, the size and hydrophobicity of the active site strongly indicated that indeed the enzyme may catalyze the unusual compound sodorifen
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
The function of the RNA-binding protein CHLAMY1 in the circadian clock and its temperature integration process
Full text linkThe research of this thesis focused on the circadian RNA-binding protein CHLAMY1 from the green alga Chlamydomonas reinhardtii that consists of two subunits, C1 and C3. CHLAMY1 binds specifically to (UG)≥7-repeat sequences situated in the 3'-UTRs of several mRNAs such as nitrite reductase 1 (nii1). The role of the C1 subunit within the circadian system was characterized by silencing its gene by an RNAi. The expression level of C1 was silenced down to 25 - 85%. To show the influence of CHLAMY1 on circadian output, NII activities were measured. In wild-type, NII activity peaks around the beginning of subjective day. In the transgenic strain arrhythmicity was observed. Circadian phototaxis was chosen as a second output rhythm. In this case, arrhythmicity was observed immediately or in the first three days under constant conditions in transgenic lines. In addition to these results, a co-regulation between C1 and C3 subunits was found. These data indicate a central role of the C1 subunit in the circadian system of C. reinhardtii. It was also analyzed if the two subunits play a role in temperature integration. C1 was found to be hyper-phosphorylated at 18°C and hypo-phosphorylated at 28°C. The C3 expression level was found to be up-regulated at 18°C, which was shown to occur at the transcriptional level. The clock-relevant CASEIN KINASE1 (CK1) and Ser-/Thr-PROTEIN PHOSPHATASEs (PPs) were found to mediate the temperature dependent regulation of C1 and C3. The expression of CK1 was itself temperature controlled and increased at 28°C. In the long period clock mutant per1 temperature integration of both C1 and C3 was shown to be altered: a low phosphorylation level of C1 and a high expression level of C3 was observed at different temperatures. Altogether, the data suggest that a temperature controlled functional network of clock-relevant proteins exists in C. reinhardtii including C1, C3, CK1, PPs and PER1
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Manipulation of the plant microbiome: Antimicrobial peptide expression in Nicotiana attenuata
Full text linkEndophytic bacteria are believed to be important for plant growth, plant health and plant resistance. But the exploration of these roles in nature is difficult. To be able to manipulate endophytic bacteria of Nicotiana attenuata, I made 11 different genotypes for the constitutive expression of antimicrobial peptides under a 35S promoter. Several plant lines showed gene expression loss and a promoter methylation analysis by bisulfite sequencing revealed epigenetic gene silencing. The augmentation of the silencing occurred independently from a generational change and plants developed epigenetic changes solely during normal plant development with rapid methylation increase in somatic cells. Lines with low promoter methylation and trans-generational stable gene expression where further analyzed in peptide abundance. The peptide accumulation of each genotype was directly analyzed in the apoplast by a new and versatile nanoUPLC-MSE method suitable for the absolute quantification of peptides allowing the selection of lines with high peptide levels. The in planta activities against 19 different bacterial strains were examined by leaf infiltration and confirmed in vivo activity only for a single genotype, the so called ICE line, expressing a knottin from the common ice plant. This line showed high taxa specific activity against most Bacilli but did not affect proteobacteria and most actinobacteria. The different native Bacillus isolates showed distinct susceptibilities against the peptide indicating a high heterogeneity within wild isolates, which allows bacterial communities to compensate for antimicrobial activity by diversity. Plants were further used for comparative growth studies in the native environment, showed no reduction in growth performance and harbored a similar bacterial community, observed by high throughput pyrosequencing
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