1-20 von 1111 Publikationen

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      A CRISPR-Cas9-Based Toolkit for Fast and Precise In Vivo Genetic Engineering of Bacillus subtilis Phages 

      Schilling, Tobias; Dietrich, Sascha; Hoppert, Michael; Hertel, Robert
      Viruses 2018; 10(5): Art. 241
      Phages are currently under discussion as a solution for the antibiotic crisis, as they may cure diseases caused by multi-drug-resistant pathogens. However, knowledge of phage biology and genetics is limited, which impedes risk assessment of therapeutic applications. In order to enable advances in phage genetic research, the aim of this work was to create a toolkit for simple and fast genetic engineering of phages recruiting Bacillus subtilis as host system. The model organism B. subtilis represents a non-pathogenic surrogate of its harmful relatives, such as Bacillus anthracis or Bacillus cereus. This toolkit comprises the application CutSPR, a bioinformatic tool for rapid primer design, and facilitates the cloning of specific CRISPR-Cas9-based mutagenesis plasmids. The employment of the prophage-free and super-competent B. subtilis TS01 strain enables an easy and fast introduction of specific constructs for in vivo phage mutagenesis. Clean gene deletions and a functional clean gene insertion into the genome of the model phage vB_BsuP-Goe1 served as proof of concept and demonstrate reliability and high efficiency. The here presented toolkit allows comprehensive investigation of the diverse phage genetic pool, a better understanding of phage biology, and safe phage applications.
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      Reconstructing geographical parthenogenesis: effects of niche differentiation and reproductive mode on Holocene range expansion of an alpine plant. 

      Kirchheimer, Bernhard; Wessely, Johannes; Gattringer, Andreas; Hülber, Karl; Moser, Dietmar; Schinkel, Christoph C. F.; Appelhans, Marc; Klatt, Simone; Caccianiga, Marco; Dellinger, Agnes; et al.
      Guisan, AntoineKuttner, MichaelLenoir, JonathanMaiorano, LuigiNieto-Lugilde, DiegoPlutzar, ChristophSvenning, Jens-ChristianWillner, WolfgangHörandl, ElviraDullinger, Stefan
      Ecology Letters 2018; 21(3) p.392-401
      Asexual taxa often have larger ranges than their sexual progenitors, particularly in areas affected by Pleistocene glaciations. The reasons given for this 'geographical parthenogenesis' are contentious, with expansion of the ecological niche or colonisation advantages of uniparental reproduction assumed most important in case of plants. Here, we parameterized a spread model for the alpine buttercup Ranunculus kuepferi and reconstructed the joint Holocene range expansion of its sexual and apomictic cytotype across the European Alps under different simulation settings. We found that, rather than niche broadening or a higher migration rate, a shift of the apomict's niche towards colder conditions per se was crucial as it facilitated overcoming of topographical barriers, a factor likely relevant for many alpine apomicts. More generally, our simulations suggest potentially strong interacting effects of niche differentiation and reproductive modes on range formation of related sexual and asexual taxa arising from their differential sensitivity to minority cytotype disadvantage.
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      A toolkit for Nannochloropsis oceanica CCMP1779 enables gene stacking and genetic engineering of the eicosapentaenoic acid pathway for enhanced long-chain polyunsaturated fatty acid production 

      Poliner, Eric; Pulman, Jane A.; Zienkiewicz, Krzysztof; Childs, Kevin; Benning, Christoph; Farré, Eva M.
      Plant Biotechnology Journal 2018; 16(1) p.298-309
      Nannochloropsis oceanica is an oleaginous microalga rich in ω3 long-chain polyunsaturated fatty acids (LC-PUFAs) content, in the form of eicosapentaenoic acid (EPA). We identified the enzymes involved in LC-PUFA biosynthesis in N. oceanica CCMP1779 and generated multigene expression vectors aiming at increasing LC-PUFA content in vivo. We isolated the cDNAs encoding four fatty acid desaturases (FAD) and determined their function by heterologous expression in S. cerevisiae. To increase the expression of multiple fatty acid desaturases in N. oceanica CCMP1779, we developed a genetic engineering toolkit that includes an endogenous bidirectional promoter and optimized peptide bond skipping 2A peptides. The toolkit also includes multiple epitopes for tagged fusion protein production and two antibiotic resistance genes. We applied this toolkit, towards building a gene stacking system for N. oceanica that consists of two vector series, pNOC-OX and pNOC-stacked. These tools for genetic engineering were employed to test the effects of the overproduction of one, two or three desaturase-encoding cDNAs in N. oceanica CCMP1779 and prove the feasibility of gene stacking in this genetically tractable oleaginous microalga. All FAD overexpressing lines had considerable increases in the proportion of LC-PUFAs, with the overexpression of Δ12 and Δ5 FAD encoding sequences leading to an increase in the final ω3 product, EPA.
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      Cyanophage-encoded lipid desaturases: oceanic distribution, diversity and function 

      Roitman, Sheila; Hornung, Ellen; Flores-Uribe, José; Sharon, Itai; Feussner, Ivo; Béjà, Oded
      The ISME Journal 2018; 12(2) p.343-355
      Cyanobacteria are among the most abundant photosynthetic organisms in the oceans; viruses infecting cyanobacteria (cyanophages) can alter cyanobacterial populations, and therefore affect the local food web and global biochemical cycles. These phages carry auxiliary metabolic genes (AMGs), which rewire various metabolic pathways in the infected host cell, resulting in increased phage fitness. Coping with stress resulting from photodamage appears to be a central necessity of cyanophages, yet the overall mechanism is poorly understood. Here we report a novel, widespread cyanophage AMG, encoding a fatty acid desaturase (FAD), found in two genotypes with distinct geographical distribution. FADs are capable of modulating the fluidity of the host's membrane, a fundamental stress response in living cells. We show that both viral FAD (vFAD) families are Δ9 lipid desaturases, catalyzing the desaturation at carbon 9 in C16 fatty acid chains. In addition, we present a comprehensive fatty acid profiling for marine cyanobacteria, which suggests a unique desaturation pathway of medium- to long-chain fatty acids no longer than C16, in accordance with the vFAD activity. Our findings suggest that cyanophages are capable of fiddling with the infected host's membranes, possibly leading to increased photoprotection and potentially enhancing viral-encoded photosynthetic proteins, resulting in a new viral metabolic network.
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      Dendrochronologically dated pine stumps document phase-wise bog expansion at a northwest German site between ca. 6700 and ca. 3400 BC 

      Achterberg, Inke Elisabeth Maike; Eckstein, Jan; Birkholz, Bernhard; Bauerochse, Andreas; Leuschner, Hanns Hubert
      Climate of the Past 2018; 14(1) p.85-100
      The investigated northwest German mire site at "Totes Moor" is densely covered with subfossil pine stumps (Pinus sylvestris L.) from the fen–bog transition. This facilitates the spatio-temporal reconstruction of mire development, which is based on 212 in situ tree stumps in the case study presented here. Six dendrochronologically dated site chronologies together cover 2345 years between 6703 and 3403 BC. The gaps in between are 6 to 550 years long. Additionally, a floating chronology of 309 years, containing 30 trees, was radiocarbon-dated to the beginning of the 7th millennium cal BC. Peat-stratigraphical survey was carried out additionally, and elevations a.s.l. were determined at several locations. Tree dying-off phases, which indicate water level rise at the site, mostly in context of the local fen–bog transition, are evident for ca. 6600–6450, ca. 6350–5750, ca. 5300–4900, ca. 4700–4550, ca. 3900–3850, ca. 3700–3600, ca. 3500–3450 and ca. 3400 BC. The spatial distribution of the dated in situ trees illustrates the phase-wise expansion of raised bog over fen peat at the site. The documented bog expansion pulses likely correspond to climatic wet sifts.
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      Long-Term Outcomes of a Multimodal Day-Clinic Treatment for Chronic Pain under the Conditions of Routine Care 

      Preis, Mira A.; Vögtle, Elisabeth; Dreyer, Nele; Seel, Stefanie; Wagner, Ruth; Hanshans, Klaus; Reyersbach, Renate; Pieh, Christoph; Mühlberger, Andreas; Probst, Thomas
      Pain Research and Management 2018; 2018 p.1-7
      Chronic pain has high prevalence rates and is one of the top causes of years lived with disability. The aim of the present study was to evaluate the long-term effects of a multimodal day-clinic treatment for chronic pain. The sample included 183 chronic pain patients (114 females and 69 males; 53.3 ± 9.8 years) who participated in a four-week multimodal day-clinic treatment for chronic pain. The patients’ average current pain intensity (NRS), sensory and affective pain (Pain Perception Scale), and depression and anxiety (HADS) were assessed at pre- and posttreatment, as well as at three follow-ups (one month, six months, and twelve months after completion of the treatment). Multilevel models for discontinuous change were performed to evaluate the change of the outcome variables. Improvements from pretreatment to posttreatment and from pretreatment to all follow-ups emerged for pain intensity (NRS; 0.54 ≤ d ≤ 0.74), affective pain (Pain Perception Scale; 0.24 ≤ d ≤ 0.47), depression (HADS; 0.38 ≤ d ≤ 0.53), and anxiety (HADS; 0.26 ≤ d ≤ 0.43) (all ). Sensory pain as assessed with the Pain Perception Scale did not show any significant change. Patients suffering from chronic pain benefited from the multimodal pain treatment up to twelve months after completion of the treatment.
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      High-level accumulation of oleyl oleate in plant seed oil by abundant supply of oleic acid substrates to efficient wax ester synthesis enzymes. 

      Yu, Dan; Hornung, Ellen; Iven, Tim; Feussner, Ivo
      Biotechnology for Biofuels 2018; 11 p.1-14: Art. 53
      Background: Biotechnology enables the production of high-valued industrial feedstocks from plant seed oil. The plant-derived wax esters with long-chain monounsaturated acyl moieties, like oleyl oleate, have favorite properties for lubrication. For biosynthesis of wax esters using acyl-CoA substrates, expressions of a fatty acyl reductase (FAR) and a wax synthase (WS) in seeds are sufficient. Results: For optimization of the enzymatic activity and subcellular localization of wax ester synthesis enzymes, two fusion proteins were created, which showed wax ester-forming activities in Saccharomyces cerevisiae. To promote the formation of oleyl oleate in seed oil, WSs from Acinetobactor baylyi (AbWSD1) and Marinobacter aquaeolei (MaWS2), as well as the two created fusion proteins were tested in Arabidopsis to evaluate their abilities and substrate preference for wax ester production. The tested seven enzyme combinations resulted in different yields and compositions of wax esters. Expression of a FAR of Marinobacter aquaeolei (MaFAR) with AbWSD1 or MaWS2 led to a high incorporation of C18 substrates in wax esters. The MaFAR/TMMmAWAT2-AbWSD1 combination resulted in the incorporation of more C18:1 alcohol and C18:0 acyl moieties into wax esters compared with MaFAR/AbWSD1. The fusion protein of a WS from Simmondsia chinensis (ScWS) with MaFAR exhibited higher specificity toward C20:1 substrates in preference to C18:1 substrates. Expression of MaFAR/AbWSD1 in the Arabidopsis fad2 fae1 double mutant resulted in the accumulation of oleyl oleate (18:1/18:1) in up to 62 mol% of total wax esters in seed oil, which was much higher than the 15 mol% reached by MaFAR/AbWSD1 in Arabidopsis Col-0 background. In order to increase the level of oleyl oleate in seed oil of Camelina, lines expressing MaFAR/ScWS were crossed with a transgenic high oleate line. The resulting plants accumulated up to >40 mg g seed-1 of wax esters, containing 27-34 mol% oleyl oleate. Conclusions: The overall yields and the compositions of wax esters can be strongly affected by the availability of acyl-CoA substrates and to a lesser extent, by the characteristics of wax ester synthesis enzymes. For synthesis of oleyl oleate in plant seed oil, appropriate wax ester synthesis enzymes with high catalytic efficiency and desired substrate specificity should be expressed in plant cells; meanwhile, high levels of oleic acid-derived substrates need to be supplied to these enzymes by modifying the fatty acid profile of developing seeds.
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      Design and Manual to Construct Rainout-Shelters for Climate Change Experiments in Agroecosystems 

      Kundel, Dominika; Meyer, Svenja; Birkhofer, Herbert; Fliessbach, Andreas; Mäder, Paul; Scheu, Stefan; van Kleunen, Mark; Birkhofer, Klaus
      Frontiers in Environmental Science 2018; 6: Art. 14
      Climate change models predict reduced summer precipitations for most European countries, including more frequent and extreme summer droughts. Rainout-shelters which intercept part of the natural precipitation provide an effective tool to investigate effects of different precipitation levels on biodiversity and ecosystem functioning. In this study, we evaluate and describe in detail a fixed-location rainout-shelter (2.5 × 2.5 m) with partial interception of natural rainfall. We provide a complete parts list, a construction manual and detailed CAD drawings allowing to rebuild and use these shelters for rainfall manipulation studies. In addition, we describe a rainout-shelter control treatment giving the possibility to quantify and account for potential shelter artifacts. To test the rainout-shelters, we established the following three treatments each in eight winter wheat plots of the agricultural long-term farming system comparison trial DOK in Therwil (Switzerland): (1) A rainout-shelter with 65% interception of rainfall, (2) a rainout-shelter control without interception of rainfall, and (3) an ambient control. The rainout-shelter effectively excluded 64.9% of the ambient rainfall, which is very close to the a priori calculated exclusion of 65.1%. In comparison to the ambient control plots, gravimetric soil moisture decreased under the rainout-shelter by a maximum of 11.1 percentage points. Air temperature under the rainout-shelter differed little from the ambient control (−0.55◦C in 1.2 m height and +0.19◦C in 0.1 m height), whereas soil temperatures were slightly higher in periods of high ambient temperature (+1.02◦C), but remained basically unaffected in periods of low ambient temperature (+0.14◦C). A maximum edge effect of 0.75 m defined a sampling area of 1 × 1 m under the rainout-shelter. The rainout-shelters presented here, proved to sustain under heavy weather and they were well-suited to be used in agricultural fields where management operations require the removal of the rainout-shelters for management operations. Overall, the results confirmed the good performance of the presented rainout-shelters regarding rainout-shelter artifacts, predictable rain exclusion, and feasibility for experimental studies in agricultural fields.
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      The 'forma specialis' issue in Fusarium: A case study in Fusarium solani f. sp. pisi 

      Šišić, Adnan; Baćanović-Šišić, Jelena; Al-Hatmi, Abdullah M. S.; Karlovsky, Petr; Ahmed, Sarah A.; Maier, Wolfgang; de Hoog, G. Sybren; Finckh, Maria R.
      Scientific Reports 2018; 8(1) p.1252-1252
      The Fusarium solani species complex (FSSC) has been studied intensively but its association with legumes, particularly under European agro-climatic conditions, is still poorly understood. In the present study, we investigated phylogenetic relationships and aggressiveness of 79 isolates of the FSSC collected from pea, subterranean clover, white clover and winter vetch grown under diverse agro-climatic and soil conditions within Temperate and Mediterranean Europe. The isolates were characterized by sequencing tef1 and rpb2 loci and by greenhouse aggressiveness assays. The majority of the isolates belonged to two lineages: the F. pisi comb. nov. lineage (formerly F. solani f. sp. pisi) mainly accommodating German and Swiss isolates, and the Fusisporium (Fusarium) solani lineage accommodating mainly Italian isolates. Based on the results of aggressiveness tests on pea, most of the isolates were classified as weakly to moderately aggressive. In addition, using one model strain, 62 accessions of 10 legume genera were evaluated for their potential to host F. pisi, the species known mainly as a pathogen of pea. A total of 58 accessions were colonized, with 25 of these being asymptomatic hosts. These results suggest a broad host range for F. pisi and challenge the forma specialis naming system in Fusarium.
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      Allene oxide synthase, allene oxide cyclase and jasmonic acid levels in Lotus japonicus nodules. 

      Zdyb, Anna; Salgado, Marco G.; Demchenko, Kirill N.; Brenner, Wolfram G.; Płaszczyca, Małgorzata; Stumpe, Michael; Herrfurth, Cornelia; Feussner, Ivo; Pawlowski, Katharina
      PLOS ONE 2018; 13(1): Art. e0190884
      Jasmonic acid (JA), its derivatives and its precursor cis-12-oxo phytodienoic acid (OPDA) form a group of phytohormones, the jasmonates, representing signal molecules involved in plant stress responses, in the defense against pathogens as well as in development. Elevated levels of JA have been shown to play a role in arbuscular mycorrhiza and in the induction of nitrogen-fixing root nodules. In this study, the gene families of two committed enzymes of the JA biosynthetic pathway, allene oxide synthase (AOS) and allene oxide cyclase (AOC), were characterized in the determinate nodule-forming model legume Lotus japonicus JA levels were to be analysed in the course of nodulation. Since in all L. japonicus organs examined, JA levels increased upon mechanical disturbance and wounding, an aeroponic culture system was established to allow for a quick harvest, followed by the analysis of JA levels in whole root and shoot systems. Nodulated plants were compared with non-nodulated plants grown on nitrate or ammonium as N source, respectively, over a five week-period. JA levels turned out to be more or less stable independently of the growth conditions. However, L. japonicus nodules formed on aeroponically grown plants often showed patches of cells with reduced bacteroid density, presumably a stress symptom. Immunolocalization using a heterologous antibody showed that the vascular systems of these nodules also seemed to contain less AOC protein than those of nodules of plants grown in perlite/vermiculite. Hence, aeroponically grown L. japonicus plants are likely to be habituated to stress which could have affected JA levels.
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      Transient Activation of Apomixis in Sexual Neotriploids May Retain Genomically Altered States and Enhance Polyploid Establishment 

      Hojsgaard, Diego
      Frontiers in Plant Science 2018; 9: Art. 230
      Polyploid genomes evolve and follow a series of dynamic transfigurations along with adaptation and speciation. The initial formation of a new polyploid individual within a diploid population usually involves a triploid bridge, a two-step mechanism of cell fusions between ubiquitous (reduced) and rare (unreduced) gametes. The primary fusion event creates an intermediate triploid individual with unbalanced genome sets, a situation of genomic-shock characterized by gene expression dysregulation, high dosage sensitivity, disturbed cell divisions, and physiological and reproductive attributes drastically altered. This near-sterile neotriploid must produce (even) eupolyploids through secondary fusion events to restore genome steadiness, meiotic balance, and fertility required for the demographic establishment of a nascent lineage. Natural conditions locate several difficulties to polyploid establishment, including the production of highly unbalanced and rarely unreduced (euploid) gametes, frequency-dependent disadvantages (minority cytotype exclusion), severe fitness loss, and ecological competition with diploid parents. Persistence and adaptation of neopolyploids depend upon genetic and phenotypic novelty coupled to joint selective forces that preserve shock-induced genomic changes (subgenome homeolog partitioning) and drive meiotic (reproductive) stabilization and ecological diversification. Thus, polyploid establishment through the triploid bridge is a feasible but not ubiquitous process that requires a number of low-probability events and singular circumstances. Yet, frequencies of polyploids suggest that polyploid establishment is a pervasive process. To explain this disparity, and supported in experimental evidence, I propose that situations like hybridization and ploidy-state transitions associated to genomic shock and substantial developmental alterations can transiently activate apomixis as a mechanism to halt genomic instability and cancel factors restraining neopolyploid’s sexual fertility, particularly in triploids. Apomixis –as a temporal alternative to sex– skip meiosis and syngamy, and thus can freeze genomic attributes, avoid unbalanced chromosomal segregation and increase the formation of unreduced euploid gametes, elude frequency-dependent reproductive disadvantages by parthenogenetic development of the embryo and permissive development of endosperm during seed formation, and increase the effective population size of the neopolyploid lineage favoring the formation rate of eupolyploids compared to aneuploids. The subsequent action of genome resilience mechanisms that alleviate transcriptomic shock and selection upon gene interactions might restore a stable meiosis and sexual fertility within few generations, as observed in synthetic polyploids. Alternatively, provided that resilience mechanisms fail, the neopolyploid might retain apomixis and hold genomically and transcriptionally altered states for many generations.
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      Comparative genome and phenotypic analysis of three Clostridioides difficile strains isolated from a single patient provide insight into multiple infection of C. difficile. 

      Groß, Uwe; Brzuszkiewicz, Elzbieta; Gunka, Katrin; Starke, Jessica; Riedel, Thomas; Bunk, Boyke; Spröer, Cathrin; Wetzel, Daniela; Poehlein, Anja; Chibani, Cynthia; et al.
      Bohne, WolfgangOvermann, JörgZimmermann, OrtrudDaniel, RolfLiesegang, Heiko
      BMC Genomics 2018; 19(1) p.1-14
      BACKGROUND: Clostridioides difficile infections (CDI) have emerged over the past decade causing symptoms that range from mild, antibiotic-associated diarrhea (AAD) to life-threatening toxic megacolon. In this study, we describe a multiple and isochronal (mixed) CDI caused by the isolates DSM 27638, DSM 27639 and DSM 27640 that already initially showed different morphotypes on solid media. RESULTS: The three isolates belonging to the ribotypes (RT) 012 (DSM 27639) and 027 (DSM 27638 and DSM 27640) were phenotypically characterized and high quality closed genome sequences were generated. The genomes were compared with seven reference strains including three strains of the RT 027, two of the RT 017, and one of the RT 078 as well as a multi-resistant RT 012 strain. The analysis of horizontal gene transfer events revealed gene acquisition incidents that sort the strains within the time line of the spread of their RTs within Germany. We could show as well that horizontal gene transfer between the members of different RTs occurred within this multiple infection. In addition, acquisition and exchange of virulence-related features including antibiotic resistance genes were observed. Analysis of the two genomes assigned to RT 027 revealed three single nucleotide polymorphisms (SNPs) and apparently a regional genome modification within the flagellar switch that regulates the fli operon. CONCLUSION: Our findings show that (i) evolutionary events based on horizontal gene transfer occur within an ongoing CDI and contribute to the adaptation of the species by the introduction of new genes into the genomes, (ii) within a multiple infection of a single patient the exchange of genetic material was responsible for a much higher genome variation than the observed SNPs.
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      Dynamic genome wide expression profiling of Drosophila head development reveals a novel role of Hunchback in retinal glia cell development and blood-brain barrier integrity. 

      Torres-Oliva, Montserrat; Schneider, Julia; Wiegleb, Gordon; Kaufholz, Felix; Posnien, Nico
      PLOS Genetics 2018; 14(1): Art. e1007180
      Drosophila melanogaster head development represents a valuable process to study the developmental control of various organs, such as the antennae, the dorsal ocelli and the compound eyes from a common precursor, the eye-antennal imaginal disc. While the gene regulatory network underlying compound eye development has been extensively studied, the key transcription factors regulating the formation of other head structures from the same imaginal disc are largely unknown. We obtained the developmental transcriptome of the eye-antennal discs covering late patterning processes at the late 2nd larval instar stage to the onset and progression of differentiation at the end of larval development. We revealed the expression profiles of all genes expressed during eye-antennal disc development and we determined temporally co-expressed genes by hierarchical clustering. Since co-expressed genes may be regulated by common transcriptional regulators, we combined our transcriptome dataset with publicly available ChIP-seq data to identify central transcription factors that co-regulate genes during head development. Besides the identification of already known and well-described transcription factors, we show that the transcription factor Hunchback (Hb) regulates a significant number of genes that are expressed during late differentiation stages. We confirm that hb is expressed in two polyploid subperineurial glia cells (carpet cells) and a thorough functional analysis shows that loss of Hb function results in a loss of carpet cells in the eye-antennal disc. Additionally, we provide for the first time functional data indicating that carpet cells are an integral part of the blood-brain barrier. Eventually, we combined our expression data with a de novo Hb motif search to reveal stage specific putative target genes of which we find a significant number indeed expressed in carpet cells.
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      Effects of Inundation, Nutrient Availability and Plant Species Diversity on Fine Root Mass and Morphology Across a Saltmarsh Flooding Gradient. 

      Redelstein, Regine; Dinter, Thomas; Hertel, Dietrich; Leuschner, Christoph
      Frontiers in Plant Science 2018; 9: Art. 98
      Saltmarsh plants are exposed to multiple stresses including tidal inundation, salinity, wave action and sediment anoxia, which require specific root system adaptations to secure sufficient resource capture and firm anchorage in a temporary toxic environment. It is well known that many saltmarsh species develop large below-ground biomass (roots and rhizomes) but relations between fine roots, in particular, and the abiotic conditions in salt marshes are widely unknown. We studied fine root mass (<2 mm in diameter), fine root depth distribution and fine root morphology in three typical communities (Spartina anglica-dominated pioneer zone,Atriplex portulacoides-dominated lower marsh,Elytrigia atherica-dominated upper marsh) across elevational gradients in two tidal salt marshes of the German North Sea coast [a mostly sandy marsh on a barrier island (Spiekeroog), and a silty-clayey marsh on the mainland coast (Westerhever)]. Fine root mass in the 0-40 cm profile ranged between 750 and 2,500 g m-2in all plots with maxima at both sites in the lower marsh with intermediate inundation frequency and highest plant species richness indicating an effect of biodiversity on fine root mass. Fine root mass and, even more, total fine root surface area (maximum 340 m2m-2) were high compared to terrestrial grasslands, and were greater in the nutrient-poorer Spiekeroog marsh. Fine root density showed only a slight or no decrease toward 40 cm depth. We conclude that the standing fine root mass and morphology of these salt marshes is mainly under control of species identity and nutrient availability, but species richness is especially influential. The plants of the pioneer zone and lower marsh possess well adapted fine roots and large standing root masses despite the often water-saturated sediment.
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      The structure of salt marsh soil mesofauna food webs - The prevalence of disturbance 

      Haynert, Kristin; Kiggen, Mirijam; Klarner, Bernhard; Maraun, Mark; Scheu, Stefan
      PloS one 2017; 12(12) p.1-20: Art. e0189645
      Mesofauna taxa fill key trophic positions in soil food webs, even in terrestrial-marine boundary habitats characterized by frequent natural disturbances. Salt marshes represent such boundary habitats, characterized by frequent inundations increasing from the terrestrial upper to the marine pioneer zone. Despite the high abundance of soil mesofauna in salt marshes and their important function by facilitating energy and carbon flows, the structure, trophic ecology and habitat-related diet shifts of mesofauna species in natural salt marsh habitats is virtually unknown. Therefore, we investigated the effects of natural disturbance (inundation frequency) on community structure, food web complexity and resource use of soil mesofauna using stable isotope analysis (15N, 13C) in three salt marsh zones. In this intertidal habitat, the pioneer zone is exposed to inundations twice a day, but lower and upper salt marshes are less frequently inundated based on shore height. The mesofauna comprised 86 species / taxa dominated by Collembola, Oribatida and Mesostigmata. Shifts in environmental disturbances influenced the structure of food webs, diversity and density declined strongly from the land to the sea pointing to the importance of increasing levels of inundation frequency. Accordingly, the reduced diversity and density was associated by a simplification of the food web in the pioneer zone as compared to the less inundated lower and upper salt marsh with a higher number of trophic levels. Strong variations in δ15N signatures demonstrated that mesofauna species are feeding at multiple trophic levels. Primary decomposers were low and most mesofauna species functioned as secondary decomposers or predators including second order predators or scavengers. The results document that major decomposer taxa, such as Collembola and Oribatida, are more diverse than previously assumed and predominantly dwell on autochthonous resources of the respective salt marsh zone. The results further suggest that Mesostigmata mostly adopt an intraguild predation lifestyle. The high trophic position of a large number of predators suggests that intraguild predation is of significant importance in salt marsh food webs. Presumably, intraguild predation contributes to stabilizing the salt marsh food web against disturbances.
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      Reduction of the Hawaiian genusPlatydesmainto Melicope section Pelea (Rutaceae) and notes on the monophyly of the section. 

      Appelhans, Marc S.; Wood, Kenneth R.; Wagner, Warren L.
      PhytoKeys(91) p.125-137
      Platydesma , an endemic genus to the Hawaiian Islands containing four species, has long been considered of obscure origin. Recent molecular phylogenetic studies have unequivocally placedPlatydesmawithin the widespread genusMelicopeas sister to the rest of the Hawaiian species ofMelicope. This makes submergingPlatydesmaintoMelicopenecessary. We make the necessary new combinations:Melicope cornuta(Hillebr.) Appelhans, K.R. Wood & W.L. Wagner, M. cornuta var. decurrens (B.C.Stone) Appelhans, K.R. Wood & W.L. Wagner,M. remyi(Sherff) Appelhans, K.R. Wood & W.L. Wagner, andM. rostrata(Hillebr.) Appelhans, K.R. Wood & W.L. Wagner. An additional species that has been recognized withinPlatydesmashould now be recognized under its original nameM. spathulataA. Gray. All Hawaiian species belong to Melicope section Pelea. Our molecular phylogenetic studies also showed that in addition to merging Platydesma into section Pelea, five species described from New Caledonia need to be excluded from the section in order to achieve monophyly of section Pelea.
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      Paediatric Headache: A New Perspective on Treatment 

      Kröner-Herwig, Birgit
      Austin Journal of Clinical Neurology 2015; 2(9) p.1-4: Art. 1080
      Headache is a widespread pain problem in children and adolescents in a large number of countries. Data on its prevalence and its association with other pain problems and somatic and psychological symptoms is presented. The paper focuses on treatments for headache outside the standard medical canon, which are grounded in the biopsychosocial model of pain. The main interventions evaluated in this field are relaxation training, biofeedback and cognitive behavioural therapy. A currently expanding area of research on Internet-based self-management programs is described. There is evidence of high improvement rates due to psychological treatments and their sustainability. The status of evidence is reviewed and perspectives in this field are discussed.
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      Key Components of Different Plant Defense Pathways Are Dispensable for Powdery Mildew Resistance of the Arabidopsis mlo2 mlo6 mlo12 Triple Mutant. 

      Kuhn, Hannah; Lorek, Justine; Kwaaitaal, Mark; Consonni, Chiara; Becker, Katia; Micali, Cristina; Ver Loren van Themaat, Emiel; Bednarek, Paweł; Raaymakers, Tom M.; Appiano, Michela; et al.
      Bai, YulingMeldau, DorotheaBaum, StephaniConrath, UweFeussner, IvoPanstruga, Ralph
      Frontiers in plant science 2017; 8: Art. 1006
      Loss of function mutations of particular plant MILDEW RESISTANCE LOCUS O (MLO) genes confer durable and broad-spectrum penetration resistance against powdery mildew fungi. Here, we combined genetic, transcriptomic and metabolomic analyses to explore the defense mechanisms in the fully resistant Arabidopsis thaliana mlo2 mlo6 mlo12 triple mutant. We found that this genotype unexpectedly overcomes the requirement for indolic antimicrobials and defense-related secretion, which are critical for incomplete resistance of mlo2 single mutants. Comparative microarray-based transcriptome analysis of mlo2 mlo6 mlo12 mutants and wild type plants upon Golovinomyces orontii inoculation revealed an increased and accelerated accumulation of many defense-related transcripts. Despite the biotrophic nature of the interaction, this included the non-canonical activation of a jasmonic acid/ethylene-dependent transcriptional program. In contrast to a non-adapted powdery mildew pathogen, the adapted powdery mildew fungus is able to defeat the accumulation of defense-relevant indolic metabolites in a MLO protein-dependent manner. We suggest that a broad and fast activation of immune responses in mlo2 mlo6 mlo12 plants can compensate for the lack of single or few defense pathways. In addition, our results point to a role of Arabidopsis MLO2, MLO6, and MLO12 in enabling defense suppression during invasion by adapted powdery mildew fungi.
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      Driving factors and temporal fluctuation of Collembola communities and reproductive mode across forest types and regions. 

      Pollierer, Melanie M.; Scheu, Stefan
      Ecology and evolution 2017-06; 7(12) p.4390-4403
      Despite the major role of Collembola in forest soil animal food webs, ecological and evolutionary determinants of their community composition are not well understood. We investigated abundance, community structure, life forms, and reproductive mode of Collembola in four different forest types (coniferous, young managed beech, old managed beech, and unmanaged beech forests) representing different management intensities. Forest types were replicated within three regions across Germany: the Schorfheide-Chorin, the Hainich, and the Swabian Alb, differing in geology, altitude, and climate. To account for temporal variation, samples were taken twice with an interval of 3 years. To identify driving factors of Collembola community structure, we applied structural equation modeling, including an index of forest management intensity, abiotic and biotic factors such as pH, C-to-N ratio of leaf litter, microbial biomass, and fungal-to-bacterial ratio. Collembola abundance, biomass, and community composition differed markedly between years, with most pronounced differences in the Schorfheide, the region with the harshest climatic conditions. There, temporal fluctuations of parthenogenetic Collembola were significantly higher than in the other regions. In the year with the more favorable conditions, parthenogenetic species flourished, with their abundance depending mainly on abiotic, density-independent factors. This is in line with the "Structured Resource Theory of Sexual Reproduction," stating that parthenogenetic species are favored if density-independent factors, such as desiccation, frost or flooding, prevail. In contrast, sexual species in the same year were mainly influenced by resource quality-related factors such as the fungal-to-bacterial ratio and the C-to-N ratio of leaf litter. The influence of forest management intensity on abundances was low, indicating that disturbance through forest management plays a minor role. Accordingly, differences in community composition were more pronounced between regions than between different forest types, pointing to the importance of regional factors.
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      Habitat selection by Eurasian lynx (Lynx lynx) is primarily driven by avoidance of human activity during day and prey availability during night. 

      Filla, Marc; Premier, Joseph; Magg, Nora; Dupke, Claudia; Khorozyan, Igor; Waltert, Matthias; Bufka, Luděk; Heurich, Marco
      Ecology and evolution 2017-08; 7(16) p.6367-6381
      The greatest threat to the protected Eurasian lynx (Lynx lynx) in Central Europe is human-induced mortality. As the availability of lynx prey often peaks in human-modified areas, lynx have to balance successful prey hunting with the risk of encounters with humans. We hypothesized that lynx minimize this risk by adjusting habitat choices to the phases of the day and over seasons. We predicted that (1) due to avoidance of human-dominated areas during daytime, lynx range use is higher at nighttime, that (2) prey availability drives lynx habitat selection at night, whereas high cover, terrain inaccessibility, and distance to human infrastructure drive habitat selection during the day, and that (3) habitat selection also differs between seasons, with altitude being a dominant factor in winter. To test these hypotheses, we analyzed telemetry data (GPS, VHF) of 10 lynx in the Bohemian Forest Ecosystem (Germany, Czech Republic) between 2005 and 2013 using generalized additive mixed models and considering various predictor variables. Night ranges exceeded day ranges by more than 10%. At night, lynx selected open habitats, such as meadows, which are associated with high ungulate abundance. By contrast, during the day, lynx selected habitats offering dense understorey cover and rugged terrain away from human infrastructure. In summer, land-cover type greatly shaped lynx habitats, whereas in winter, lynx selected lower altitudes. We concluded that open habitats need to be considered for more realistic habitat models and contribute to future management and conservation (habitat suitability, carrying capacity) of Eurasian lynx in Central Europe.
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