Doctoral Researchers

 
Raguž, Luka

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Institute/Dep.
Leibniz Institute for Natural Product Research and Infection Biology - Hans-Knöll-Institute-
Junior Research Group
Chemical Biology of Microbe-Host Interactions
PhD Project:

Molecular synthetic approaches towards natural sphingoid base-type signaling molecules

Abstract: Sphingoid bases and sphingolipids are essential multifunctional cellular compounds, which serve not only as integral components of cell membranes, but also as essential regulatory...
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... signals for fundamental cellular processes. They were first thought to exist exclusively in eukaryotes, but have now been repeatedly identified and isolated from important bacterial and viral sources. Despite being abundant signaling molecules, the biological function of many sphingolipid derivatives remains elusive. Prominent examples of fungal origin are sphingofungins and myriocin (ISP-1), which exhibit antifungal activity in the picomolar to nanomolar range. Their discovery has led to the development of many pharmaceutical drug leads (e.g. FTY720 and safingol. But the intrinsic biological role of sphingofungins is unknown until to date. In another study bacterial sulfonolipids, such as RIF-1 and RIF-2, regulate an onset of development in one of the closest living relatives of animals, the choanoflagellate Salpingoeca rosetta. A structural analog IOR-1 inhibits partially the activity of RIF molecules. Due to their intrinsic biological function of these types of molecules, this research project will focus on efficient and new synthetic strategies towards of rare microbial sphingoid base-type signaling molecules to allow their detailed functional analysis.
 
 
Ray, Rishav

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IMPRS Student

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Institute/Dep.
Max Planck Institute for Chemical Ecology
Dept. Molecular Ecology
PhD Project:

The role of root associated microbiome in plant herbivore interaction in N. attenuata

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Abstract: Plants are the primary producers in two distinct environments: aboveground where they acquire energy, and belowground where they acquire nutrients and water. Plants are at the base of...
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... trophic interactions in both environments, and actively facilitate communication between the two through chemical cues. Roots residing belowground are much harder to study and thus less understood than shoots, including in our ecological model plant, Nicotiana attenuata, where it is important to study them in ecologically relevant field conditions. It has been shown that intraspecific variation in host genotypes alters the heritability of the microbiome and provides us with an opportunity to identify the genetic components associated with it in the host plant. Employing a multi-parent advanced generation inter-cross (MAGIC) population, we will use a forward genetics approach to identify the genetic components involved both in plant-herbivore interactions, and in belowground interactions with root-dwellers. Furthermore, integrating the metabolic and transcriptional changes of plants elicited by aboveground herbivores, along with metagenomic analyses of the microbial community in roots, we aim to derive a coherent picture of the molecular communication taking place via the plant. Additionally, by leveraging the transgenic techniques developed for N. attenuata, we will apply a reverse genetics approach to test the specific genetic components of interest identified under field conditions. The goal of this project is to understand the multitrophic interaction of root dwelling microorganisms with above ground herbivores which has ecological and agricultural significance.
 
 
Rischer, Maja

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ILRS Student

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Institute/Dep.
Leibniz Institute for Natural Product Research and Infection Biology - Hans-Knöll-Institute-
Junior Research Group
Chemical Biology of Microbe-Host Interactions
PhD Project:

Exploring the chemical potential and mechanisms of marine microbe-invertebrate interactions

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Abstract: Metamorphosis in marine invertebrate larvae is often an environmentally dependent process and larvae of many marine invertebrates use biofilm components as cues to appropriate...
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... settlement sites (habitats). In many phyla species of the bacterial genus Pseudoalteromonas induce larval settlement and metamorphosis, but despite century long intensive research, we still know very little about the bacterial ligands that stimulate larval settlement and the cellular basis of their detection by larvae.
We have chosen the colonial marine hydroid Hydractinia echinata as model organism, which grows on the shells inhabited by hermit crabs. Here, it is long known that the metamorphosis from free-swimming larvae to the sessile polyp is particularly stimulated by bacteria of the genus Pseudoalteromonas. This project will first focus on the characterization of the specific bacterial morphogenic factor from a highly inductive Pseudoalteromonas strain using a combination of various methods (molecular biology, genome analysis, proteomics, and imaging).
Biofilm and invertebrate settlement are part of the so-called ‘biofouling community’ that inhabit artificial surfaces and cause major economic losses around the globe. Analysing the settlement mechanisms might lead to new strategies to prevent biofouling, and decrease the current use of environmentally harmful and toxic antifouling agents.
As a second project we will analyse the chemical potential of microbes associated with H. echinata. It is known that Cnidara cultures are sensible to infection and parasitic infestation when they have lost important microbial commensals and symbionts. We hypothesize that microbial commensals contribute by secretion of antimicrobial compounds to the host defense and therefore represent a very promising source of biologically important natural products. We have established a collection of wildtype bacteria and fungi from the tissue surface of healthy polyps, which are currently under investigation using bioassay-guided fractionation and other dereplication methods. Isolation and structure identification of antimicrobial secondary metabolites is performed by using different analytical techniques like HPLC, NMR, UV-VIS and others. Based on sequenced genomes we want to investigate biosynthetic pathways of the characterized molecules and predict unknown secondary metabolite clusters through genome mining.
 
 
Röcker, Marie

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ILRS Student

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Institute/Dep.
Leibniz Institute for Natural Product Research and Infection Biology - Hans-Knöll-Institute-
Dept. Molecular and Applied Microbiology
PhD Project:

Identification of immunogenic components of Aspergillus fumigatus for vaccine development

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Abstract: Aspergillus fumigatus is the most important air-borne fungal pathogen. In recent years, it became evident that certain unknown components of A. fumigatus apparently lead to protection...
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... against invasive aspergillosis in a mouse infection model. Until now, it remains to be shown whether the protection is due to a B cell response or rather T cell response. Furthermore, the components of A. fumigatus triggering this response have not been identified. The proposed project will investigate, which morphotypes (spore, mycelium) promote an immune response and which protein antigens contribute to this host reaction. The immunological properties of selected protein antigens will be further investigated in murine models of Invasive Aspergillosis (B-cells, T-cells). In collaboration with the Charite´ (Berlin) the T-cell response against Invasive Aspergillosis of Cystic Fibrosis patients will be characterized.
 
 
Rudolphi, Sven

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FungiNet Student

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Institute/Dep.
Leibniz Institute for Natural Product Research and Infection Biology - Hans-Knöll-Institute-
Research Group
Microbial Immunology
PhD Project:

Host-pathogen interactions during Candida albicans translocation through the gut