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153 Publications visible to you, out of a total of 153
Calcium carbonates: induced biomineralization with controlled macromorphology

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Biomineralization of (magnesium) calcite and vaterite by bacterial isolates has been known for quite some time. However, the extracellular precipitation has hardly ever been linked to different … morphologies of the minerals that are observed. Here, isolates from limestone-associated groundwater, rock and soil were shown to form calcite, magnesium calcite or vaterite. More than 92 % of isolates were indeed able to form carbonates, while abiotic controls failed to form minerals. The crystal morphologies varied, including rhombohedra, prisms and pyramid-like macromorphologies. Different conditions like varying temperature, pH or media components, but also cocultivation to test for collaborative effects of sympatric bacteria, were used to differentiate between mechanisms of calcium carbonate formation. Single crystallites were cemented with bacterial cells; these may have served as nucleation sites by providing a basic pH at short distance from the cells. A calculation of potential calcite formation of up to 2 g L−1 of solution made it possible to link the microbial activity to geological processes.

Authors: Aileen Meier, Anne Kastner, Dennis Harries, Maria Wierzbicka-Wieczorek, Juraj Majzlan, Georg Büchel, Erika Kothe

Date Published: 6th Nov 2017

Publication Type: Not specified

CASSIS and SMIPS: promoter-based prediction of secondary metabolite gene clusters in eukaryotic genomes

Abstract (Expand)

MOTIVATION: Secondary metabolites (SM) are structurally diverse natural products of high pharmaceutical importance. Genes involved in their biosynthesis are often organized in clusters, i.e., are … co-localized and co-expressed. In silico cluster prediction in eukaryotic genomes remains problematic mainly due to the high variability of the clusters' content and lack of other distinguishing sequence features. RESULTS: We present Cluster Assignment by Islands of Sites (CASSIS), a method for SM cluster prediction in eukaryotic genomes, and Secondary Metabolites by InterProScan (SMIPS), a tool for genome-wide detection of SM key enzymes ('anchor' genes): polyketide synthases, non-ribosomal peptide synthetases and dimethylallyl tryptophan synthases. Unlike other tools based on protein similarity, CASSIS exploits the idea of co-regulation of the cluster genes, which assumes the existence of common regulatory patterns in the cluster promoters. The method searches for 'islands' of enriched cluster-specific motifs in the vicinity of anchor genes. It was validated in a series of cross-validation experiments and showed high sensitivity and specificity. AVAILABILITY AND IMPLEMENTATION: CASSIS and SMIPS are freely available at https://sbi.hki-jena.de/cassis CONTACT: thomas.wolf@leibniz-hki.de or ekaterina.shelest@leibniz-hki.de SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Authors: T. Wolf, V. Shelest, N. Nath,

Date Published: 9th Dec 2015

Publication Type: Not specified

Catechol, a major component of smoke, influences primary root growth and root hair elongation through reactive oxygen species-mediated redox signaling

Abstract (Expand)

Nicotiana attenuata germinates from long-lived seedbanks in native soils after fires. Although smoke signals have been known to break seed dormancy, whether they also affect seedling establishment and … root development remains unclear. In order to test this, seedlings were treated with smoke solutions. Seedlings responded in a dose-dependent manner with significantly increased primary root lengths, due mainly to longitudinal cell elongation, increased numbers of lateral roots and impaired root hair development. Bioassay-driven fractionations and NMR were used to identify catechol as the main active compound for the smoke-induced root phenotype. The transcriptome analysis revealed that mainly genes related to auxin biosynthesis and redox homeostasis were altered after catechol treatment. However, histochemical analyses of reactive oxygen species (ROS) and the inability of auxin applications to rescue the phenotype clearly indicated that highly localized changes in the root's redox-status, rather than in levels of auxin, are the primary effector. Moreover, H2 O2 application rescued the phenotype in a dose-dependent manner. Chemical cues in smoke not only initiate seed germination, but also influence seedling root growth; understanding how these cues work provides new insights into the molecular mechanisms by which plants adapt to post-fire environments.

Authors: M. Wang, M. Schoettner, S. Xu, C. Paetz, J. Wilde, I. T. Baldwin, K. Groten

Date Published: 24th Nov 2016

Publication Type: Not specified

Cell structure and microtubule organisation during gametogenesis of Ulva mutabilis Føyn (Chlorophyta)

Abstract (Expand)

Cell structure and microtubule organisation during gametogenesis of the green alga Ulva mutabilis was studied using light microscopy, transmission electron microscopy (TEM) and tubulin immunofluorescence. … Microtubules in vegetative cells are organised in parallel bundles traversing the cortical cytoplasm. During gametogenesis, induced blade cells are transformed to gametangia, depending on the maturity of the algae and the removal of regulatory sporulation inhibitors. This differentiation is accompanied by formation of a conical cell projection (papilla) towards the exterior of the thallus. Microtubules form a clear, basket-like configuration converging towards the conical tip, but not reaching it. The conical microtubule structure stops below the tip, leaving a circular “opening”. Parallel to the above, the cell wall of the tip is differentiated, forming a “cap”. Nuclear divisions start at this stage, finally forming the nuclei of future gametes. Cytokinesis takes place by membrane furrowing and vesicle fusion, giving rise to 16 oval-shaped gametes. The conical microtubule organisation is gradually depolymerised, and a cortical, intensely fluorescing microtubule bundle is formed in each gamete. At this stage, the cap at the conical cell wall projection is removed and the exit pore opens. The biflagellate gametes remain initially motionless, connected by thin cytoplasmic bridges. Finally, they are released to the environment upon additional removal of a swarming inhibitor accumulated in the growth medium during gametogenesis. Keywords: cell differentiation; gametogenesis; green macroalgae; immunofluorescence; microtubule cytoskeleton

Authors: Thomas Wichard, Christos Katsaros, Anne Weiss, Ira Llangos

Date Published: 11th Jan 2017

Publication Type: Not specified

Chemical Mediators at the Bacterial-Fungal Interface.

Abstract (Expand)

Interactions among microbes are key drivers of evolutionary progress and constantly shape ecological niches. Microorganisms rely on chemical communication to interact with each other and surrounding … organisms. They synthesize natural products as signaling molecules, antibiotics, or modulators of cellular processes that may be applied in agriculture and medicine. Whereas major insight has been gained into the principles of intraspecies interaction, much less is known about the molecular basis of interspecies interplay. In this review, we summarize recent progress in the understanding of chemically mediated bacterial-fungal interrelations. We discuss pairwise interactions among defined species and systems involving additional organisms as well as complex interactions among microbial communities encountered in the soil or defined as microbiota of higher organisms. Finally, we give examples of how the growing understanding of microbial interactions has contributed to drug discovery and hypothesize what may be future directions in studying and engineering microbiota for agricultural or medicinal purposes.

Authors: K. Scherlach, C. Hertweck

Date Published: 8th Sep 2020

Publication Type: Journal

Chemical warfare between leafcutter ant symbionts and a co-evolved pathogen.

Abstract (Expand)

Acromyrmex leafcutter ants form a mutually beneficial symbiosis with the fungus Leucoagaricus gongylophorus and with Pseudonocardia bacteria. Both are vertically transmitted and actively maintained by … the ants. The fungus garden is manured with freshly cut leaves and provides the sole food for the ant larvae, while Pseudonocardia cultures are reared on the ant-cuticle and make antifungal metabolites to help protect the cultivar against disease. If left unchecked, specialized parasitic Escovopsis fungi can overrun the fungus garden and lead to colony collapse. We report that Escovopsis upregulates the production of two specialized metabolites when it infects the cultivar. These compounds inhibit Pseudonocardia and one, shearinine D, also reduces worker behavioral defenses and is ultimately lethal when it accumulates in ant tissues. Our results are consistent with an active evolutionary arms race between Pseudonocardia and Escovopsis, which modifies both bacterial and behavioral defenses such that colony collapse is unavoidable once Escovopsis infections escalate.

Authors: D. Heine, N. A. Holmes, S. F. Worsley, A. C. A. Santos, T. M. Innocent, K. Scherlach, E. H. Patrick, D. W. Yu, J. C. Murrell, P. C. Vieria, J. J. Boomsma, C. Hertweck, M. I. Hutchings, B. Wilkinson

Date Published: 7th Jun 2018

Publication Type: Journal

Colonization of the Intestinal Tract of the Polyphagous Pest Spodoptera littoralis with the GFP-Tagged Indigenous Gut Bacterium Enterococcus mundtii

Abstract (Expand)

The alkaline gut of Lepidopterans plays a crucial role in shaping communities of bacteria. Enterococcus mundtii has emerged as one of the predominant gut microorganisms in the gastrointestinal tract … of the major agricultural pest, Spodoptera littoralis. Therefore, it was selected as a model bacterium to study its adaptation to harsh alkaline gut conditions in its host insect throughout different stages of development (larvae, pupae, adults, and eggs). To date, the mechanism of bacterial survival in insects' intestinal tract has been unknown. Therefore, we have engineered a GFP-tagged species of bacteria, E. mundtii, to track how it colonizes the intestine of S. littoralis. Three promoters of different strengths were used to control the expression of GFP in E. mundtii. The promoter ermB was the most effective, exhibiting the highest GFP fluorescence intensity, and hence was chosen as our main construct. Our data show that the engineered fluorescent bacteria survived and proliferated in the intestinal tract of the insect at all life stages for up to the second generation following ingestion.

Authors: , J. Apel, Y. Shao,

Date Published: 6th Jul 2016

Publication Type: Not specified

Comments on the distribution and phylogeny of type I polyketide synthases and nonribosomal peptide synthetases in eukaryotes

Abstract

Not specified

Editor:

Date Published: 2nd Sep 2014

Publication Type: Not specified

Comparative genomics reveals high biological diversity and specific adaptations in the industrially and medically important fungal genus Aspergillus.

Abstract (Expand)

BACKGROUND: The fungal genus Aspergillus is of critical importance to humankind. Species include those with industrial applications, important pathogens of humans, animals and crops, a source of potent … carcinogenic contaminants of food, and an important genetic model. The genome sequences of eight aspergilli have already been explored to investigate aspects of fungal biology, raising questions about evolution and specialization within this genus. RESULTS: We have generated genome sequences for ten novel, highly diverse Aspergillus species and compared these in detail to sister and more distant genera. Comparative studies of key aspects of fungal biology, including primary and secondary metabolism, stress response, biomass degradation, and signal transduction, revealed both conservation and diversity among the species. Observed genomic differences were validated with experimental studies. This revealed several highlights, such as the potential for sex in asexual species, organic acid production genes being a key feature of black aspergilli, alternative approaches for degrading plant biomass, and indications for the genetic basis of stress response. A genome-wide phylogenetic analysis demonstrated in detail the relationship of the newly genome sequenced species with other aspergilli. CONCLUSIONS: Many aspects of biological differences between fungal species cannot be explained by current knowledge obtained from genome sequences. The comparative genomics and experimental study, presented here, allows for the first time a genus-wide view of the biological diversity of the aspergilli and in many, but not all, cases linked genome differences to phenotype. Insights gained could be exploited for biotechnological and medical applications of fungi.

Authors: R. P. de Vries, R. Riley, A. Wiebenga, G. Aguilar-Osorio, S. Amillis, C. A. Uchima, G. Anderluh, M. Asadollahi, M. Askin, K. Barry, E. Battaglia, O. Bayram, T. Benocci, S. A. Braus-Stromeyer, C. Caldana, D. Canovas, G. C. Cerqueira, F. Chen, W. Chen, C. Choi, A. Clum, R. A. Dos Santos, A. R. Damasio, G. Diallinas, T. Emri, E. Fekete, M. Flipphi, S. Freyberg, A. Gallo, C. Gournas, R. Habgood, M. Hainaut, M. L. Harispe, B. Henrissat, K. S. Hilden, R. Hope, A. Hossain, E. Karabika, L. Karaffa, Z. Karanyi, N. Krasevec, A. Kuo, H. Kusch, K. LaButti, E. L. Lagendijk, A. Lapidus, A. Levasseur, E. Lindquist, A. Lipzen, A. F. Logrieco, A. MacCabe, M. R. Makela, I. Malavazi, P. Melin, V. Meyer, N. Mielnichuk, M. Miskei, A. P. Molnar, G. Mule, C. Y. Ngan, M. Orejas, E. Orosz, J. P. Ouedraogo, K. M. Overkamp, H. S. Park, G. Perrone, F. Piumi, P. J. Punt, A. F. Ram, A. Ramon, S. Rauscher, E. Record, D. M. Riano-Pachon, V. Robert, J. Rohrig, R. Ruller, A. Salamov, N. S. Salih, R. A. Samson, E. Sandor, M. Sanguinetti, T. Schutze, K. Sepcic, E. Shelest, G. Sherlock, V. Sophianopoulou, F. M. Squina, H. Sun, A. Susca, R. B. Todd, A. Tsang, S. E. Unkles, N. van de Wiele, D. van Rossen-Uffink, J. V. Oliveira, T. C. Vesth, J. Visser, J. H. Yu, M. Zhou, M. R. Andersen, D. B. Archer, S. E. Baker, I. Benoit, A. A. Brakhage, G. H. Braus, R. Fischer, J. C. Frisvad, G. H. Goldman, J. Houbraken, B. Oakley, I. Pocsi, C. Scazzocchio, B. Seiboth, P. A. vanKuyk, J. Wortman, P. S. Dyer, I. V. Grigoriev

Date Published: 16th Feb 2017

Publication Type: Not specified

Conspecificity of the model organism Ulva mutabilis and Ulva compressa (Ulvophyceae, Chlorophyta).

Abstract (Expand)

As one of the most abundant and ubiquitous representatives of marine and brackish coastal macrophytobenthos communities, the genus Ulva is not only an important primary producer but also of ecological … and morphogenetic interest to many scientists. Ulva mutabilis became an important model organism to study morphogenesis and mutualistic interactions of macroalgae and microorganisms. Here, we report that our collections of Ulva compressa Linnaeus (1753) from Germany are conspecific with the type strains of the model organism U. mutabilis Foyn (1958), which were originally collected at Olhao on the south coast of Portugal and have from that time on been maintained in culture as gametophytic and parthenogenetic lab strains. Different approaches were used to test conspecificity: (i) comparisons of vegetative and reproductive features of cultured material of U. mutabilis and German U. compressa demonstrated a shared morphological pattern; (ii) gametes of U. compressa and U. mutabilis successfully mated and developed into fertile sporophytic first-generation offspring; (iii) molecular phylogenetics and species delimitation analyses based on the Generalized Mixed Yule-Coalescent method showed that U. mutabilis isolates (sl-G[mt+]) and (wt-G[mt-]) and U. compressa belong to a unique Molecular Operational Taxonomic Unit. According to these findings, there is sufficient evidence that U. mutabilis and U. compressa should be regarded as conspecific.

Authors: S. Steinhagen, A. Barco, T. Wichard, F. Weinberger

Date Published: 28th Oct 2018

Publication Type: Journal

Crossing the blood-brain barrier: Glutathione-conjugated poly(ethylene imine) for gene delivery

Abstract (Expand)

The targeted drug delivery to the central nervous system represents one of the major challenges in pharmaceutical formulations since it is strictly limited through the highly selective blood-brain … barrier (BBB). l-Glutathione (GSH), a tripeptide and well-known antioxidant, has been studied in the last years as potential candidate to facilitate the receptor-mediated transcytosis of nanocarriers. We thus tested whether GSH decoration of a positively charged polymer, poly(ethylene imine), with this vector enables the transport of genetic material and, simultaneously, the passage through the BBB. In this study, we report the synthesis of GSH conjugated cationic poly(ethylene imine)s via ecologically desirable thiol-ene photo-addition. The copolymers, containing 80% primary or secondary amine groups, respectively, were investigated concerning their bio- and hemocompatibility as well as their ability to cross a hCMEC/D3 endothelial cell layer mimicking the BBB within microfluidically perfused biochips. We demonstrate that BBB passage depends on the used amino-groups and on the GSH ratio. Thereby the copolymer containing secondary amines showed an enhanced performance. We thus conclude that GSH-coupling represents a feasible and promising approach for the functionalization of nanocarriers intended to cross the BBB for the delivery of drugs to the central nervous system.

Authors: , A. K. Trutzschler, M. Raasch, T. Bus, P. Borchers, A. S. Mosig, A. Traeger,

Date Published: 19th Oct 2016

Publication Type: Not specified

Cultivation-Free Raman Spectroscopic Investigations of Bacteria.

Abstract (Expand)

Raman spectroscopy is currently advertised as a hot and ambitious technology that has all of the features needed to characterize and identify bacteria. Raman spectroscopy is rapid, easy to use, … noninvasive, and it could complement established microbiological and biomolecular methods in the near future. To bring this vision closer to reality, ongoing research is being conducted on spectral fingerprinting. This can yield a wealth of information, from even single bacteria from various habitats which can be further improved by combining Raman spectroscopy with methods such as stable isotope probing to elucidate microbial interactions. In conjunction with extensive statistical analysis, Raman spectroscopy will allow identification of (non)pathogenic bacteria at different taxonomic levels.

Authors: B. Lorenz, C. Wichmann, S. Stockel, P. Rosch, J. Popp

Date Published: 12th Feb 2017

Publication Type: Not specified

Cyclopropanol Warhead in Malleicyprol Confers Virulence of Human- and Animal-Pathogenic Burkholderia Species.

Abstract (Expand)

Burkholderia species such as B. mallei and B. pseudomallei are bacterial pathogens causing fatal infections in humans and animals (glanders and melioidosis), yet knowledge on their virulence factors … is limited. While pathogenic effects have been linked to a highly conserved gene locus (bur/mal) in the B. mallei group, the metabolite associated to the encoded polyketide synthase, burkholderic acid (syn. malleilactone), could not explain the observed phenotypes. By metabolic profiling and molecular network analyses of the model organism B. thailandensis, the primary products of the cryptic pathway were identified as unusual cyclopropanol-substituted polyketides. First, sulfomalleicyprols were identified as inactive precursors of burkholderic acid. Furthermore, a highly reactive upstream metabolite, malleicyprol, was discovered and obtained in two stabilized forms. Cell-based assays and a nematode infection model showed that the rare natural product confers cytotoxicity and virulence.

Authors: F. Trottmann, J. Franke, I. Richter, K. Ishida, M. Cyrulies, H. M. Dahse, L. Regestein, C. Hertweck

Date Published: 1st Oct 2019

Publication Type: Journal

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