Metatranscriptomics reveal differences in in situ energy and nitrogen metabolism among hydrothermal vent snail symbionts

Despite the ubiquity of chemoautotrophic symbioses at hydrothermal vents, our understanding of the influence of environmental chemistry on symbiont metabolism is limited. Transcriptomic analyses are useful for linking physiological poise to environmental conditions, but recovering samples from the deep sea is challenging, as the long recovery times can change expression profiles before preservation. Here, we present a novel, in situ RNA sampling and preservation device, which we used to compare the symbiont metatranscriptomes associated with Alviniconcha, a genus of vent snail, in which specific host–symbiont combinations are predictably distributed across a regional geochemical gradient. Metatranscriptomes of these symbionts reveal key differences in energy and nitrogen metabolism relating to both environmental chemistry (that is, the relative expression of genes) and symbiont phylogeny (that is, the specific pathways employed). Unexpectedly, dramatic differences in expression of transposases and flagellar genes suggest that different symbiont types may also have distinct life histories. These data further our understanding of these symbionts' metabolic capabilities and their expression in situ, and suggest an important role for symbionts in mediating their hosts' interaction with regional-scale differences in geochemistry

Etudes théoriques des fluides confinés en milieux poreux et des supramolécules en solution

LYON-ENS Sciences (693872304) / SudocSudocFranceF

Manufacture of cryostat components for Wendelstein 7-X

Wendelstein 7-X (W7-X) is a follow-up of the successful stellarator W7-AS and is presently being built at the Greifswald branch institute of IPP. One of the main parts of the stellarator is the cryostat, which provides the thermal protection of the coil system. Construction of the cryostat of W7-X is based on the experience gained during design, construction and test of the demo-cryostat [Fusion Eng. Des. 56–57 (2001) 861]. The design of the main components of the cryostat, in particular the plasma vessel, the outer vessel, the ports and the support structure is finished, and manufacture by European industry has started

Status of the construction of the W7-X magnet system

The Stellarator of the Wendelstein 7-X (W7-X) experiment contains a superconductive magnet system comprising 70 coils and a central support structure. The magnet. system has been designed with respect to the physics aims of the experiment. Based on these main features, the components have been ordered from European industry. The subsequently detailed design of the single components and recent prototype test results required the modification of some features. The final design of the components is described in the contribution