Recent Submissions

  • Journal Article

    Stimulus dependencies of an illusory motion: Investigations of the Motion Bridging Effect 

    Stein, Maximilian; Fendrich, Robert; Mattler, Uwe
    Journal of Vision 2019; 19(5) p.1-23: Art. 13
    The Motion Bridging Effect (MBE) is an illusion in which a motion that is not consciously visible generates a visible motion aftereffect that is predominantly in the same direction as the adapter motion. In the initial study of the MBE (Mattler & Fendrich, 2010), a ring of 16 points was rotated at angular velocities as high as 2250°/s so that observers saw only an unbroken outline circle and performed at chance when asked to report the ring's rotation direction. However, when the rotating ring was replaced by a veridically stationary ring of 16 points, the stationary ring appeared to visibly spin to a halt, principally in the same direction as the initial ring's rotation. Here we continue to investigate the stimulus dependencies of the MBE. We find the MBE, measured by the correspondence between the direction of the invisible rotation of the spinning ring and perceived rotation of the stationary ring, increases as the number of points used to construct the rings decreases and grows stronger as the diameter of the rings get larger. We consider the potential contributions of temporal frequency, retinal eccentricity, luminance levels, and the separation between the points forming the rings as mediators of these effects. Data is discussed with regard to the detection of real movement and apparent motion. We conclude that the detection of the rapid rotation of the spinning ring is likely to be modulated by temporal frequency of luminance changes along the ring perimeter while the point-distance may modulate an apparent motion produced by the transition from the perceptually unbroken spinning ring to the point-defined stationary ring.
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  • Journal Article

    Action priming suppression by forward masks 

    Becker, Nicolas; Mattler, Uwe
    Journal of Vision 2019; 19(5) p.1-16: Art. 1085
    Visual stimuli may produce strong and reliable effects on subsequent actions irrespective of their visibility. This dissociation between action priming and conscious perception of the stimuli suggests two ways of processing of visual stimuli. One way of processing leads to the emergence of conscious visual perception, and another way leads to action priming effects. Here we examined the influence of forward masks that precede the prime on processing for action. In three experiments, we found that forward masks can suppress and even abolish priming effects. Suppression was larger with strong rather than weak forward masks and with short rather than long prime durations. Similar suppression effects occurred with surrounding paracontrast masks and with overlapping pattern masks. Our findings emphasize that processing for action depends crucially on preceding stimuli suggesting that action priming may depend on the initial part of the response to the prime. Results indicate that the use of forward masks to reduce prime visibility may also reduce action priming and potentially other priming effects.
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  • Journal Article

    The impact of powerful authorities and trustful taxpayers: evidence for the extended slippery slope framework from Austria, Finland, and Hungary 

    Gangl, Katharina; Hofmann, Eva; Hartl, Barbara; Berkics, Mihály
    Policy Studies p.1-14
    Tax authorities utilize a wide range of instruments to motivate honest taxpaying ranging from strict audits to fair procedures or personalized support, differing from country to country. However, little is known about how these different instruments and taxpayers’ trust influence the generation of interaction climates between tax authorities and taxpayers, motivations to comply, and particularly, tax compliance. The present research examines the extended slippery slope framework (eSSF), which distinguishes tax authorities’ instruments into different qualities of power of authority (coercive and legitimate) and trust in authorities (reason-based and implicit), to shed light on the effect of differences between power and trust. We test eSSF assumptions with survey data from taxpayers from three culturally different countries (N = 700) who also vary concerning their perceptions of power, trust, interaction climates, and tax motivations. Results support assumptions of the eSSF. Across all countries, the relation of coercive power and tax compliance was mediated by implicit trust. The connection from legitimate power to tax compliance is partially mediated by reason-based trust. The relationship between implicit trust and tax compliance is mediated by a confidence climate and committed cooperation. Theoretical and practical implications are discussed.
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  • Journal Article

    Proximal and distal control for ligand binding in neuroglobin: role of the CD loop and evidence for His64 gating 

    Exertier, Cécile; Milazzo, Lisa; Freda, Ida; Montemiglio, Linda Celeste; Scaglione, Antonella; Cerutti, Gabriele; Parisi, Giacomo; Anselmi, Massimiliano; Smulevich, Giulietta; Savino, Carmelinda; et al.
    Vallone, Beatrice
    Scientific Reports 2019; 9(1): Art. 5326
    Neuroglobin (Ngb) is predominantly expressed in neurons of the central and peripheral nervous systems and it clearly seems to be involved in neuroprotection. Engineering Ngb to observe structural and dynamic alterations associated with perturbation in ligand binding might reveal important structural determinants, and could shed light on key features related to its mechanism of action. Our results highlight the relevance of the CD loop and of Phe106 as distal and proximal controls involved in ligand binding in murine neuroglobin. We observed the effects of individual and combined mutations of the CD loop and Phe106 that conferred to Ngb higher CO binding velocities, which we correlate with the following structural observations: the mutant F106A shows, upon CO binding, a reduced heme sliding hindrance, with the heme present in a peculiar double conformation, whereas in the CD loop mutant "Gly-loop", the original network of interactions between the loop and the heme was abolished, enhancing binding via facilitated gating out of the distal His64. Finally, the double mutant, combining both mutations, showed a synergistic effect on CO binding rates. Resonance Raman spectroscopy and MD simulations support our findings on structural dynamics and heme interactions in wild type and mutated Ngbs.
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  • Journal Article

    Biodiversity data integration—the significance of data resolution and domain 

    König, Christian; Weigelt, Patrick; Schrader, Julian; Taylor, Amanda; Kattge, Jens; Kreft, Holger
    PLOS Biology 2019; 17(3): Art. e3000183
    ecent years have seen an explosion in the availability of biodiversity data describing the distribution, function, and evolutionary history of life on earth. Integrating these heterogeneous data remains a challenge due to large variations in observational scales, collection purposes, and terminologies. Here, we conceptualize widely used biodiversity data types according to their domain (what aspect of biodiversity is described?) and informational resolution (how specific is the description?). Applying this framework to major data providers in biodiversity research reveals a strong focus on the disaggregated end of the data spectrum, whereas aggregated data types remain largely underutilized. We discuss the implications of this imbalance for the scope and representativeness of current macroecological research and highlight the synergies arising from a tighter integration of biodiversity data across domains and resolutions. We lay out effective strategies for data collection, mobilization, imputation, and sharing and summarize existing frameworks for scalable and integrative biodiversity research. Finally, we use two case studies to demonstrate how the explicit consideration of data domain and resolution helps to identify biases and gaps in global data sets and achieve unprecedented taxonomic and geographical data coverage in macroecological analyses.
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  • Journal Article

    A Survey of Pyridoxal 5′-Phosphate-Dependent Proteins in the Gram-Positive Model Bacterium Bacillus subtilis 

    Richts, Björn; Rosenberg, Jonathan; Commichau, Fabian M.
    Frontiers in Molecular Biosciences 2019; 6: Art. 32
    The B6 vitamer pyridoxal 5′-phosphate (PLP) is a co-factor for proteins and enzymes that are involved in diverse cellular processes. Therefore, PLP is essential for organisms from all kingdoms of life. Here we provide an overview about the PLP-dependent proteins from the Gram-positive soil bacterium Bacillus subtilis. Since B. subtilis serves as a model system in basic research and as a production host in industry, knowledge about the PLP-dependent proteins could facilitate engineering the bacteria for biotechnological applications. The survey revealed that the majority of the PLP-dependent proteins are involved in metabolic pathways like amino acid biosynthesis and degradation, biosynthesis of antibacterial compounds, utilization of nucleotides as well as in iron and carbon metabolism. Many PLP-dependent proteins participate in de novo synthesis of the co-factors biotin, folate, heme, and NAD+ as well as in cell wall metabolism, tRNA modification, regulation of gene expression, sporulation, and biofilm formation. A surprisingly large group of PLP-dependent proteins (29%) belong to the group of poorly characterized proteins. This review underpins the need to characterize the PLP-dependent proteins of unknown function to fully understand the “PLP-ome” of B. subtilis.
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  • Journal Article

    Seeking consensus in German forest conservation: An analysis of contemporary concepts 

    Demant, Laura; Meyer, Peter; Sennhenn-Reulen, Holger; Walentowski, Helge; Bergmeier, Erwin; Demant, Laura; Meyer, Peter; Sennhenn-Reulen, Holger; Walentowski, Helge; Bergmeier, Erwin
    Nature Conservation 2019; 35 p.1-23
    Setting operational conservation objectives is a major challenge for effective biodiversity conservation worldwide. To analyse forest conservation objectives in Germany in a transparent manner and to achieve a consistent and consensual framework, we systematically classified conservation objectives suggested in concepts by different stakeholders. We analysed 79 biodiversity and forest conservation concepts of different stakeholder groups at various scales and applied textual content analysis and Dirichlet regression to reach a high degree of transferability and applicability. Our analysis revealed a broad consensus concerning forest conservation across stakeholders and scales, albeit with slight differences in focus, but we detected a scale-related mismatch. A wide array of conservation objectives covered social, biotic and abiotic natural resources. Conservation of species, ecosystems and structural elements in forests were found to be of primary importance across stakeholders and scale levels. Shortcomings in the conservation concepts were found in addressing genetic diversity, abiotic resources and socio-cultural objectives. Our results show that problems in forest conservation may be rooted in trade-offs between aims, targeting mismatch across scale levels and insufficient implementation of objectives.
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  • Journal Article

    Genetic mechanism underlying sexual plasticity and its association with colour patterning in zebrafish (Danio rerio) 

    Hosseini, Shahrbanou; Ha, Ngoc-Thuy; Simianer, Henner; Falker-Gieske, Clemens; Brenig, Bertram; Franke, Andre; Hörstgen-Schwark, Gabriele; Tetens, Jens; Herzog, Sebastian; Sharifi, Ahmad R
    BMC Genomics. 2019 May 06;20(1):341
    Abstract Background Elevated water temperature, as is expected through climate change, leads to masculinization in fish species with sexual plasticity, resulting in changes in population dynamics. These changes are one important ecological consequence, contributing to the risk of extinction in small and inbred fish populations under natural conditions, due to male-biased sex ratio. Here we investigated the effect of elevated water temperature during embryogenesis on sex ratio and sex-biased gene expression profiles between two different tissues, namely gonad and caudal fin of adult zebrafish males and females, to gain new insights into the molecular mechanisms underlying sex determination (SD) and colour patterning related to sexual attractiveness. Results Our study demonstrated sex ratio imbalances with 25.5% more males under high-temperature condition, resulting from gonadal masculinization. The result of transcriptome analysis showed a significantly upregulated expression of male SD genes (e.g. dmrt1, amh, cyp11c1 and sept8b) and downregulation of female SD genes (e.g. zp2.1, vtg1, cyp19a1a and bmp15) in male gonads compared to female gonads. Contrary to expectations, we found highly differential expression of colour pattern (CP) genes in the gonads, suggesting the ‘neofunctionalisation’ of those genes in the zebrafish reproduction system. However, in the caudal fin, no differential expression of CP genes was identified, suggesting the observed differences in colouration between males and females in adult fish may be due to post-transcriptional regulation of key enzymes involved in pigment synthesis and distribution. Conclusions Our study demonstrates male-biased sex ratio under high temperature condition and support a polygenic SD (PSD) system in laboratory zebrafish. We identify a subset of pathways (tight junction, gap junction and apoptosis), enriched for SD and CP genes, which appear to be co-regulated in the same pathway, providing evidence for involvement of those genes in the regulation of phenotypic sexual dimorphism in zebrafish.
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  • Journal Article

    The Role of Low Soil Temperature for Photosynthesis and Stomatal Conductance of Three Graminoids From Different Elevations 

    Göbel, Leonie; Coners, Heinz; Hertel, Dietrich; Willinghöfer, Sandra; Leuschner, Christoph
    Frontiers in Plant Science 2019; 10: Art. 330
    In high-elevation grasslands, plants can encounter periods with high air temperature while the soil remains cold, which may lead to a temporary mismatch in the physiological activity of leaves and roots. In a climate chamber experiment with graminoid species from three elevations (4400, 2400, and 250 m a.s.l.), we tested the hypothesis that soil temperature can influence photosynthesis and stomatal conductance independently of air temperature. Soil monoliths with swards of Kobresia pygmaea (high alpine), Nardus stricta (lower alpine), and Deschampsia flexuosa (upper lowland) were exposed to soil temperatures of 25, 15, 5, and -2°C and air temperatures of 20 and 10°C for examining the effect of independent soil and air temperature variation on photosynthesis, leaf dark respiration, and stomatal conductance and transpiration. Soil frost (-2°C) had a strong negative effect on gas exchange and stomatal conductance in all three species, independent of the elevation of origin. Leaf dark respiration was stimulated by soil frost in D. flexuosa, but not in K. pygmaea, which also had a lower temperature optimum of photosynthesis. Soil cooling from 15 to 5°C did not significantly reduce stomatal conductance and gas exchange in any of the species. We conclude that all three graminoids are able to maintain a relatively high root water uptake in cold, non-frozen soil, but the high-alpine K. pygmaea seems to be especially well adapted to warm shoot - cold root episodes, as it has a higher photosynthetic activity at 10 than 20°C air temperature and does not up-regulate leaf dark respiration upon soil freezing, as was observed in the grasses from warmer climates.
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  • Journal Article

    Signal peptide peptidase activity connects the unfolded protein response to plant defense suppression by Ustilago maydis 

    Pinter, Niko; Hach, Christina Andrea; Hampel, Martin; Rekhter, Dmitrij; Zienkiewicz, Krzysztof; Feussner, Ivo; Poehlein, Anja; Daniel, Rolf; Finkernagel, Florian; Heimel, Kai
    PLOS Pathogens 2019; 15(4): Art. e1007734
    The corn smut fungus Ustilago maydis requires the unfolded protein response (UPR) to maintain homeostasis of the endoplasmic reticulum (ER) during the biotrophic interaction with its host plant Zea mays (maize). Crosstalk between the UPR and pathways controlling pathogenic development is mediated by protein-protein interactions between the UPR regulator Cib1 and the developmental regulator Clp1. Cib1/Clp1 complex formation results in mutual modification of the connected regulatory networks thereby aligning fungal proliferation in planta, efficient effector secretion with increased ER stress tolerance and long-term UPR activation in planta. Here we address UPR-dependent gene expression and its modulation by Clp1 using combinatorial RNAseq/ChIPseq analyses. We show that increased ER stress resistance is connected to Clp1-dependent alterations of Cib1 phosphorylation, protein stability and UPR gene expression. Importantly, we identify by deletion screening of UPR core genes the signal peptide peptidase Spp1 as a novel key factor that is required for establishing a compatible biotrophic interaction between U. maydis and its host plant maize. Spp1 is dispensable for ER stress resistance and vegetative growth but requires catalytic activity to interfere with the plant defense, revealing a novel virulence specific function for signal peptide peptidases in a biotrophic fungal/plant interaction.
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  • Journal Article

    Why can some implicit Theory of Mind tasks be replicated and others cannot? A test of mentalizing versus submentalizing accounts 

    Kulke, Louisa; Johannsen, Josefin; Rakoczy, Hannes
    PLOS ONE 2019; 14(3): Art. e0213772
    In the last 15 years, Theory of Mind research has been revolutionized by the development of new implicit tasks. Such tasks aim at tapping children's and adults' uninstructed, largely automatic mental state ascription, indicated in spontaneous looking behavior when observing agents who act on the basis of false beliefs. Studies with anticipatory looking, in particular, have suggested that basic ToM capacities operate from very early in life and remain in unconscious operation throughout the lifespan. Recently, however, systematic replication attempts of anticipatory looking measures have yielded a complex and puzzling mixture of successful, partial and non-replications. The present study aimed at shedding light on the question whether there is a system to this pattern. More specifically, in a set of three preregistered experiments, it was tested whether those conditions that could previously be replicated and those that could not differ in crucial conceptual respects such that the former do not strictly require ToM whereas the latter do. This was tested by the implementation of novel control conditions. The results were complex. There was generally no unambiguous evidence for reliable spontaneous ToM and no effect of the number of passed familiarization trials. Neither was there any unambiguous evidence that the previous mixed patterns of (non-)replications could be explained (away) by the sub-mentalizing account tested in the new control conditions. The empirical situation remains puzzling, and the question whether there is some such thing as implicit and spontaneous ToM remains to be clarified.
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  • Journal Article

    Deprivation of root-derived resources affects microbial biomass but not community structure in litter and soil 

    Bluhm, Sarah L.; Eitzinger, Bernhard; Ferlian, Olga; Bluhm, Christian; Schröter, Kristina; Pena, Rodica; Maraun, Mark; Scheu, Stefan
    PLOS ONE 2019; 14(3): Art. e0214233
    The input of plant leaf litter has been assumed to be the most important resource for soil organisms of forest ecosystems, but there is increasing evidence that root-derived resources may be more important. By trenching roots of trees in deciduous and coniferous forests, we cut-off the input of root-derived resources and investigated the response of microorganisms using substrate-induced respiration and phospholipid fatty acid (PLFA) analysis. After one and three years, root trenching strongly decreased microbial biomass and concentrations of PLFAs by about 20%, but the microbial community structure was little affected and the effects were similar in deciduous and coniferous forests. However, the reduction in microbial biomass varied between regions and was more pronounced in forests on limestone soils (Hainich) than in those on sandy soils (Schorfheide). Trenching also reduced microbial biomass in the litter layer but only in the Hainich after one year, whereas fungal and bacterial marker PLFAs as well as the fungal-to-plant marker ratio in litter were reduced in the Schorfheide both after one and three years. The pronounced differences between forests of the two regions suggest that root-derived resources are more important in fueling soil microorganisms of base-rich forests characterized by mull humus than in forests poor in base cations characterized by moder soils. The reduction in microbial biomass and changes in microbial community characteristics in the litter layer suggests that litter microorganisms do not exclusively rely on resources from decomposing litter but also from roots, i.e. from resources based on labile recently fixed carbon. Our results suggest that both bacteria and fungi heavily depend on root-derived resources with both suffering to a similar extent to deprivation of these resources. Further, the results indicate that the community structure of microorganisms is remarkably resistant to changes in resource supply and adapts quickly to new conditions irrespective of tree species composition and forest management.
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  • Journal Article

    Species delimitation in Amblyosyllis (Annelida, Syllidae) 

    Aguado, María Teresa; Capa, María; Lago-Barcia, Domingo; Gil, João; Pleijel, Fredrik; Nygren, Arne
    PLOS ONE 2019; 14(4): Art. e0214211
    Amblyosyllis is a worldwide distributed group of annelids mainly found in coastal environments. It is well known among the polychaete specialists mostly because of its notable beauty, showing bright colourful patterns and outstanding long and coiled appendices. Amblyosyllis is a monophyletic genus easy to identify due to its distinct diagnostic features; however, the species and their boundaries are, in most cases, not well defined. Herein, we provide an extensive sample of Amblyosyllis material (115 specimens) from several world geographic areas. We have studied the morphological features of each specimen and photographed them alive. Two mitochondrial DNA markers (COI and 16S) and one nuclear gene fragment (28S, D1 region) were sequenced. We performed phylogenetic analyses based on each DNA partition, as well as the combined data sets, obtaining congruent results. Species delimitation methods such as distance analyses, statistical parsimony networks and multi-rate Poisson tree processes were also applied. The combined results obtained from different methodologies and data sets are used to differentiate between, at least, 19 lineages compatible with the separately evolving meta-populations species concept. Four of these lineages are identified as nominal species, including the type species of Amblyosyllis, A. rhombeata. For three other lineages previously synonymized names are recovered, and seven lineages are described as new species. All of these species are described and supported by appropriate iconography. We recognize several morphological characters useful to identify species of Amblyosyllis, which in some cases should also be combined with molecular methods for species delineation. The genetic divergence in the genus is high, contrary to the morphological homogeneity observed. Two species show a wide geographical distribution, while the rest have a more restricted distribution. There are several examples of species with overlapping distribution patterns.
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  • Journal Article

    Neural coding of intended and executed grasp force in macaque areas AIP, F5, and M1 

    Intveld, Rijk W.; Dann, Benjamin; Michaels, Jonathan A.; Scherberger, Hansjörg
    Scientific Reports 2018; 8(1): Art. 17985
    Considerable progress has been made over the last decades in characterizing the neural coding of hand shape, but grasp force has been largely ignored. We trained two macaque monkeys (Macaca mulatta) on a delayed grasping task where grip type and grip force were instructed. Neural population activity was recorded from areas relevant for grasp planning and execution: the anterior intraparietal area (AIP), F5 of the ventral premotor cortex, and the hand area of the primary motor cortex (M1). Grasp force was strongly encoded by neural populations of all three areas, thereby demonstrating for the first time the coding of grasp force in single- and multi-units of AIP. Neural coding of intended grasp force was most strongly represented in area F5. In addition to tuning analysis, a dimensionality reduction method revealed low-dimensional responses to grip type and grip force. Additionally, this method revealed a high correlation between latent variables of the neural population representing grasp force and the corresponding latent variables of electromyographic forearm muscle activity. Our results therefore suggest an important role of the cortical areas AIP, F5, and M1 in coding grasp force during movement execution as well as of F5 for coding intended grasp force.
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  • Journal Article

    Peri-hand space expands beyond reach in the context of walk-and-reach movements 

    Berger, Michael; Neumann, Peter; Gail, Alexander
    Scientific Reports 2019; 9(1): Art. 3013
    The brain incorporates sensory information across modalities to be able to interact with our environment. The peripersonal space (PPS), defined by a high level of crossmodal interaction, is centered on the relevant body part, e.g. the hand, but can spatially expand to encompass tools or reach targets during goal-directed behavior. Previous studies considered expansion of the PPS towards goals within immediate or tool-mediated reach, but not the translocation of the body as during walking. Here, we used the crossmodal congruency effect (CCE) to quantify the extension of the PPS and test if PPS can also expand further to include far located walk-and-reach targets accessible only by translocation of the body. We tested for orientation specificity of the hand-centered reference frame, asking if the CCE inverts with inversion of the hand orientation during reach. We show a high CCE with onset of the movement not only towards reach targets but also walk-and-reach targets. When participants must change hand orientation, the CCE decreases, if not vanishes, and does not simply invert. We conclude that the PPS can expand to the action space beyond immediate or tool-mediated reaching distance but is not purely hand-centered with respect to orientation.
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  • Journal Article

    Non-invasive genotyping with a massively parallel sequencing panel for the detection of SNPs in HPA-axis genes 

    Gutleb, D. R.; Ostner, J.; Schülke, O.; Wajjwalku, W.; Sukmak, M.; Roos, C.; Noll, A.
    Scientific Reports 2018; 8(1): Art. 15944
    We designed a genotyping panel for the investigation of the genetic underpinnings of inter-individual differences in aggression and the physiological stress response. The panel builds on single nucleotide polymorphisms (SNPs) in genes involved in the three subsystems of the hypothalamic-pituitary-adrenal (HPA)-axis: the catecholamine, serotonin and corticoid metabolism. To promote the pipeline for use with wild animal populations, we used non-invasively collected faecal samples from a wild population of Assamese macaques (Macaca assamensis). We targeted loci of 46 previously reported SNPs in 21 candidate genes coding for elements of the HPA-axis and amplified and sequenced them using next-generation Illumina sequencing technology. We compared multiple bioinformatics pipelines for variant calling and variant effect prediction. Based on this strategy and the application of different quality thresholds, we identified up to 159 SNPs with different types of predicted functional effects among our natural study population. This study provides a massively parallel sequencing panel that will facilitate integrating large-scale SNP data into behavioural and physiological studies. Such a multi-faceted approach will promote understanding of flexibility and constraints of animal behaviour and hormone physiology.
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  • Journal Article

    Cobaviruses – a new globally distributed phage group infecting Rhodobacteraceae in marine ecosystems 

    Bischoff, Vera; Bunk, Boyke; Meier-Kolthoff, Jan P.; Spröer, Cathrin; Poehlein, Anja; Dogs, Marco; Nguyen, Mary; Petersen, Jörn; Daniel, Rolf; Overmann, Jörg; et al.
    Göker, MarkusSimon, MeinhardBrinkhoff, ThorstenMoraru, Cristina
    The ISME Journal
    Bacteriophages are widely considered to influence bacterial communities, however most phages are still unknown or not studied well enough to understand their ecological roles. We have isolated two phages infecting Lentibacter sp. SH36, affiliated with the marine Roseobacter group, and retrieved similar phage genomes from publicly available metagenomics databases. Phylogenetic analysis placed the new phages within the Cobavirus group, in the here newly proposed genus Siovirus and subfamily Riovirinae of the Podoviridae. Gene composition and presence of direct terminal repeats in cultivated cobaviruses point toward a genome replication and packaging strategy similar to the T7 phage. Investigation of the genomes suggests that viral lysis of the cell proceeds via the canonical holin-endolysin pathway. Cobaviral hosts include members of the genera Lentibacter, Sulfitobacter and Celeribacter of the Roseobacter group within the family Rhodobacteraceae (Alphaproteobacteria). Screening more than 5,000 marine metagenomes, we found cobaviruses worldwide from temperate to tropical waters, in the euphotic zone, mainly in bays and estuaries, but also in the open ocean. The presence of cobaviruses in protist metagenomes as well as the phylogenetic neighborhood of cobaviruses in glutaredoxin and ribonucleotide reductase trees suggest that cobaviruses could infect bacteria associated with phototrophic or grazing protists. With this study, we expand the understanding of the phylogeny, classification, genomic organization, biogeography and ecology of this phage group infecting marine Rhodobacteraceae.
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  • Journal Article

    Evolutionary dynamics of sexual size dimorphism in non-volant mammals following their independent colonization of Madagascar 

    Kappeler, Peter M.; Nunn, Charles L.; Vining, Alexander Q.; Goodman, Steven M.
    Scientific Reports 2019; 9(1)
    As predicted by sexual selection theory, males are larger than females in most polygynous mammals, but recent studies found that ecology and life history traits also affect sexual size dimorphism (SSD) through evolutionary changes in either male size, female size, or both. The primates of Madagascar (Lemuriformes) represent the largest group of mammals without male-biased SSD. The eco-evo-devo hypothesis posited that adaptations to unusual climatic unpredictability on Madagascar have ultimately reduced SSD in lemurs after dispersing to Madagascar, but data have not been available for comparative tests of the corresponding predictions that SSD is also absent in other terrestrial Malagasy mammals and that patterns of SSD changed following the colonization of Madagascar. We used phylogenetic methods and new body mass data to test these predictions among the four endemic radiations of Malagasy primates, carnivorans, tenrecs, and rodents. In support of our prediction, we found that male-biased SSD is generally absent among all Malagasy mammals. Phylogenetic comparative analyses further indicated that after their independent colonization of Madagascar, SSD decreased in primates and tenrecs, but not in the other lineages or when analyzed across all species. We discuss several mechanisms that may have generated these patterns and conclude that neither the eco-evo-devo hypothesis, founder effects, the island rule nor sexual selection theory alone can provide a compelling explanation for the observed patterns of SSD in Malagasy mammals.
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  • Journal Article

    Analysis of the Genome and Metabolome of Marine Myxobacteria Reveals High Potential for Biosynthesis of Novel Specialized Metabolites 

    Amiri Moghaddam, Jamshid; Crüsemann, Max; Alanjary, Mohammad; Harms, Henrik; Dávila-Céspedes, Antonio; Blom, Jochen; Poehlein, Anja; Ziemert, Nadine; König, Gabriele M.; Schäberle, Till F.
    Scientific Reports 2018; 8(1): Art. 16600
    Comparative genomic/metabolomic analysis is a powerful tool to disclose the potential of microbes for the biosynthesis of novel specialized metabolites. In the group of marine myxobacteria only a limited number of isolated species and sequenced genomes is so far available. However, the few compounds isolated thereof so far show interesting bioactivities and even novel chemical scaffolds; thereby indicating a huge potential for natural product discovery. In this study, all marine myxobacteria with accessible genome data (n = 5), including Haliangium ochraceum DSM 14365, Plesiocystis pacifica DSM 14875, Enhygromyxa salina DSM 15201 and the two newly sequenced species Enhygromyxa salina SWB005 and SWB007, were analyzed. All of these accessible genomes are large (~10 Mb), with a relatively small core genome and many unique coding sequences in each strain. Genome analysis revealed a high variety of biosynthetic gene clusters (BGCs) between the strains and several resistance models and essential core genes indicated the potential to biosynthesize antimicrobial molecules. Polyketides (PKs) and terpenes represented the majority of predicted specialized metabolite BGCs and contributed to the highest share between the strains. BGCs coding for non-ribosomal peptides (NRPs), PK/NRP hybrids and ribosomally synthesized and post-translationally modified peptides (RiPPs) were mostly strain specific. These results were in line with the metabolomic analysis, which revealed a high diversity of the chemical features between the strains. Only 6-11% of the metabolome was shared between all the investigated strains, which correlates to the small core genome of these bacteria (13-16% of each genome). In addition, the compound enhygrolide A, known from E. salina SWB005, was detected for the first time and structurally elucidated from Enhygromyxa salina SWB006. The here acquired data corroborate that these microorganisms represent a most promising source for the detection of novel specialized metabolites.
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  • Journal Article

    Functional analysis of potential cleavage sites in the MERS-coronavirus spike protein 

    Kleine-Weber, Hannah; Elzayat, Mahmoud Tarek; Hoffmann, Markus; Pöhlmann, Stefan
    Scientific Reports 2018; 8(1): Art. 16597
    The Middle East respiratory syndrome-related coronavirus (MERS-CoV) can cause severe disease and has pandemic potential. Therefore, development of antiviral strategies is an important task. The activation of the viral spike protein (S) by host cell proteases is essential for viral infectivity and the responsible enzymes are potential therapeutic targets. The cellular proteases furin, cathepsin L and TMPRSS2 can activate MERS-S and may cleave the S protein at two distinct sites, termed S1/S2 and S2'. Moreover, a potential cathepsin L cleavage site in MERS-S has been reported. However, the relative importance of these sites for MERS-S activation is incompletely understood. Here, we used mutagenic analysis and MERS-S-bearing vectors to study the contribution of specific cleavage sites to S protein-driven entry. We found that an intact S1/S2 site was only required for efficient entry into cells expressing endogenous TMPRSS2. In keeping with a previous study, pre-cleavage at the S1/S2 motif (RSVR) was important although not essential for subsequent MERS-S activation by TMPRSS2, and indirect evidence was obtained that this motif is processed by a protease depending on an intact RXXR motif, most likely furin. In contrast, the S2' site (RSAR) was required for robust viral entry into all cell lines tested and the integrity of one of the two arginines was sufficient for efficient entry. These findings suggest that cleavage at S2' is carried out by proteases recognizing a single arginine, most likely TMPRSS2 and cathepsin L. Finally, mutation of the proposed cathepsin L site did not impact viral entry and double mutation of S1/S2 and S2' site was compatible with cathepsin L- but not TMPRSS2-dependent host cell entry, indicating that cathepsin L can process the S protein at auxiliary sites. Collectively, our results indicate a rigid sequence requirement for S protein activation by TMPRSS2 but not cathepsin L.
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