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Project 9

Physiological proteomics of dual symbioses of deep-sea mussels of the genus Bathymodiolus

PhD position. Supervisors: Thomas Schweder (UniGreifswald), Michael Wagner (UniVienna), and Nicole Dubilier (with input from Dörte Becher, Stephanie Markert, and Michael Hecker, UniGreifswald). Secondment internship: to UniVienna

Rationale

Mussels of the genus Bathymodiolus are found worldwide at vents and seeps in depths from 400 to 3,600 m. The bacterial symbionts occur in specialized cells of the gill, the so-called bacteriocytes. A dual symbiosis, in which a single host harbors both thiotrophic and methanotrophic bacteria, has been described for Bathymodiolus species from cold seeps in the Gulf of Mexico and from vents along the Mid-Atlantic Ridge.

Objectives

To better understand the physiological interplay between the sulfur- and methane-oxidizing symbionts and the host the objectives of the proposed PhD thesis are (i) to obtain a detailed understanding of the individual physiology of the symbionts at the proteomic level, (ii) to understand complementary metabolic mechanisms involved in establishing this symbiosis and (iii) to test for specific molecular adaptation strategies.

Key methods

To obtain a mechanistic understanding of this symbiosis the following techniques will be applied: i) density gradient centrifugation techniques to isolate specific cell fractions of the bacterial symbionts, ii) gel-based and gel-free MS analyses for the determination of the cytoplasmic and membrane proteomes, iii) comparison of proteomic data with metagenomic analyses of the symbionts (Nicole Dubilier), iv) metabolite analyses of the host and the bacterial symbionts by NMR and MS techniques (Michael Lalk), (v) Raman microscopy and NanoSIMS for studying the distribution of the symbionts inside  bacteriocytes and to analyse chemical heterogeneities (Michael Wagner).