Hertha Firnberg grant on “Benthic Ecosystem Functioning across Arctic Shelves, Slopes and Basins” to Renate Degen

Renate Degen received the three-year Hertha Firnberg grant from the Austrian Science Fund (FWF) to study the functions of macro- and megabenthic communities in the Arctic Ocean. While in recent years some information was gathered about the structural variability of Arctic benthos, information on the functional variability is currently still lacking. The aim of this project is to fill these knowledge gaps by means of a pan-Arctic, integrated approach, including i) the analysis of benthic functioning on Arctic shelves and basins and along a shelf-slope-basin gradient in the Eurasian and the Amerasian part of the Arctic, ii) the identification of functions and regions most susceptible to changes, and iii) the prediction of benthic ecosystem functioning in a future, seasonally ice free Arctic Ocean.

 
New paper in PLoS ONE

We published a new paper on the inhibition of bacterial growth by the trophosome of the giant deep-sea tubeworm Riftia pachyptila.

Julia Klose, Karin Aistleitner, Matthias Horn, Liselotte Krenn, Verena Dirsch, Martin Zehl, Monika Bright

Trophosome of the deep-sea tubeworm Riftia pachyptila inhibits bacterial growth. PLoS ONE 11(1): e0146446. doi:10.1371/journal.pone.0146446

 

 

 

 

 

 

The giant deep-sea tubeworm Riftia pachyptila lives in a mutualistic association with the chemoautotrophic gammaproteobacterium Cand. Endoriftia persephone, harbored in the host’s trophosome. Symbiont transmission is horizontal in each host generation. Escape of symbionts happens after the host dies. Surprisingly, no microbial fouling was found in degrading trophosome tissue. In high-pressure incubation experiments we could show, the antimicrobial effect of the tubeworm’s trophosome. Mainly Gram-positive bacterial strains were inhibited in growth. We could identify lysophospholipids and free fatty acids, well known antimicrobial and antifouling substances by a liquid chromatography-mass spectrometric analysis. As a result of tissue autolysis, the abundance of the free fatty acids increased with time and correlated with an increased growth inhibition of two bacterial strains. After death, the host cannot provide nutrients to the chemoautotrophic symbiont. Therefore, it is tempting to speculate that under post mortem host conditions, Endoriftia switches to a heterotrophic life style to feed on the dead host until it escapes.

 
New paper in Proceedings of the National Academy of Sciences

We published a new paper on the escape of endosymbionts from the giant tubeworm host Riftia pachyptila in the deep-sea.

Julia Klose, Martin F. Polz, Michael Wagner, Mario P. Schimak, Sabine Gollner, Monika Bright

Endosymbionts escape dead hydrothermal vent tubeworms to enrich the free-living population. Proceedings of the National Academy of Sciences, Aug, 17, 2015; published ahead of print doi:10.1073/pnas.1501160112

Maintaining the mutualism of Riftia pachyptila and its horizontally transmitted bacterial symbionts requires the symbionts to be able to escape from their hosts and replenish the free-living bacterial population. We could show, that high amounts of symbionts are released from dead host tissue under simulated deep-sea and hydrothermal vent conditions in high-pressure aquaria in the laboratory. The escaped bacteria settled on surfaces where they proliferated. Monitoring of tubeworm clumps at a hydrothermal vent field at the East Pacific Rise following a volcanic eruption exhibited rapid turnover of tubeworm clumps within two years, suggesting that large numbers of bacteria could be released over a relatively short time. The connection between the host-associated and free-living bacterial populations might explain how the symbiotic relationship between tubeworms and bacteria has remained stable over evolutionary time scales.

 
Workshop on Symbiosis April 2015

WORKSHOP ON SYMBIOSIS

The Research Focus Symbiosis of the Faculty of Life Sciences will be holding the next "Let's talk about symbiosis"- workshop on Friday the 17th of April. To register, please send an e-mail to Andrea Nussbaumer  ( This e-mail address is being protected from spambots. You need JavaScript enabled to view it ) and let her know if you want to give a presentation or just to participate. The deadline for the registration is March 27th. For the presentation, you only need to submit a title. Non-presenting participants are also required to register, so we can organize accordingly.

Please circulate this information to anyone who might be interested: Colleagues, Post-docs, PhD students, master students, etc...

 
Conference and Workshop Autumn 2014

 

Julia and Monika attended the Symbiomics Conference and 4th Annual Meeting in Palma de Mallorca, 12th to 14th November 2014. Several invited scientific leaders in symbiosis presented their work and provided valuable comments and suggestions for the PhD students of this program. All students presented their work and Julia gave a talk on her PhD thesis project: “Ecological and evolutionary role of horizontal transmission in the model system Riftia pachyptila” Little time was left in this excellent meeting for discovering Palma de Mallorca. Nevertheless, we managed to get our feet wet when taking a selfie at the beach.

 
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