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Project 8

Comparative metabolomics and systems biology of marine endosymbionts

PhD position. Supervisors: Michael Lalk (UniGreifswald) and Nicole Dubilier (MPIMM) (with input from Michael Wagner, UniVienna, and Thomas Schweder, UniGreifswald). Host: UniGreifswald. Secondment internship:to MPIMM and oceanBASIS (with input from Levent Piker).

Rationale

Symbiosis between microorganisms and invertebrates are widespread in marine environments. In different habitats like vents and seeps at depths from 400 to 3,600 m organisms were found which developed a unique relationship to bacteria as symbionts. These symbionts are highly specialized towards their hosts and environment. Examples are the deep sea tubeworms Riftia pachyptila and the gutless worm Olavius algavensis. Other communities were found in mussels and sponges (like Bathymodiolus species from cold seeps in the Gulf of Mexico and from hydrothermal vents). The metabolism of the endosymbionts of such organisms must be highly adapted towards their hosts and environmental conditions.

Objectives

The aim of this research task is the comprehensive investigation of the metabolism of endosymbionts of marine organisms. The data obtained will provide valuable information on the physiological relationships between symbionts and their host and will complement genomic, proteomic and transcriptomic datasets. The main objectives of the planned PhD thesis are (i) to establish reliable protocols for the sampling of endosymbionts form different invertebrates, (ii) to collect bioanalytical data on the intracellular bacterial metabolite pool and the host metabolites, (iii) to gain insight into fundamental metabolic regulations involved in endosymbiosis and colonization (also via the characterization of possible new signaling molecules) and (iv) to establish datasets for comparative metabolic profiling of marine endosymbionts.

Key methods

To obtain the data necessary for the investigation of metabolic aspects of endosymbiosis the following techniques will be used: i) quenching/sampling techniques for the harvesting of endosymbionts (such as quenching methodologies from eukaryotic cell cultures and host/pathogen systems of intracellular bacteria), ii) HPLC-MS analyses of subsets of intracellular metabolites (such as nucleosides, cofactors and sugar phosphates) and bioactive compounds, iii) quantitative GC/MS-analysis of the whole intracellular metabolome of endosymbionts and host cells, iv) quantitative NMR analysis of certain host and endosymbiotic metabolite pools (such as amino acids and sugars), (v) NMR and LC/MS-, GC/MS profiling analysis for comparative metabolomics studies (in connection with statistical evaluation of datasets with hierarchal cluster analysis and PCA), vi) structural characterization of new signaling molecules via NMR and MS analysis (HPLC-ESI-TOF-MS).