Anders Meibom

Biography

Anders Meibom obtained his PhD in physics from the University of Southern Denmark in 1997. This was followed by two and a half years of PostDoc work at the Hawaii Institute for Geophysics and Planetology, where he conducted mineralogical studies of primitive chondritic meteorites. From 2000 to 2005, he was Research Associate in the Geological & Environmental Sciences, Stanford University, where he represented Stanford in the USGS-Stanford ion microprobe laboratory. In 2005, he became proifessor at the Muséum National dHistoire Naturelle in Paris. From 2006 to 2011 he was the director of the French national NanoSIMS laboratory. Since January 2012, he is professor at the EPFL in the School of Architecture, Civil and Environmental Engineering (ENAC). From April 2014, he is professor ad personam at the Institute of Earth Sciences, University of Lausanne.

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Data for "Host starvation and in hospite degradation of algal symbionts shape the heat stress response of the Cassiopea-Symbiodiniaceae symbiosis"

Stéphane Laurent Escrig, Cristina Martin Olmos, Anders Meibom, Nils Rädecker, Gaëlle Delphine Toullec

Raw data associated with the publication "Host starvation and in hospite degradation of algal symbionts shape the heat stress response of the Cassiopea-Symbiodiniaceae symbiosis". Temperature profile, daily measurements, physiological measurements, elemental analysis, NanoSIMS data, and cell density data are included as individual tabs in the Excel file.

EPFL Infoscience2023

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Global warming is causing large-scale disruption of cnidarian-Symbiodiniaceae symbioses fundamental to major marine ecosystems, such as coral reefs. However, the mechanisms by which heat stress perturbs these symbiotic partnerships remain poorly understood. In this context, the upside-down jellyfish Cassiopea has emerged as a powerful experimental model system. We combined a controlled heat stress experiment with isotope labeling and correlative SEM–NanoSIMS imaging to show that host starvation is a central component in the chain of events that ultimately leads to the collapse of the Cassiopea holobiont. Heat stress caused an increase in catabolic activity and a depletion of carbon reserves in the unfed host, concurrent with a reduction in the supply of photosynthates from its algal symbionts. This state of host starvation was accompanied by pronounced in hospite degradation of algal symbionts, which may be a distinct feature of the heat stress response of Cassiopea. Interestingly, this loss of symbionts by degradation was to a large extent concealed by body shrinkage of the starving animals, resulting in what could be referred to as ’invisible’ bleaching. Overall, our study highlights the importance of the nutritional status in the heat stress response of the Cassiopea holobiont. Compared with other symbiotic cnidarians, the large mesoglea of Cassiopea, with its structural sugar and protein content, may constitute an energy reservoir capable of delaying starvation. It seems plausible that this anatomical feature at least partly contributes to the relatively high stress tolerance of these animals in our warming oceans.

2023

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The paleoseawater temperature record from the oxygen isotope compositions of fossil foraminifera tests may be biased by up to about 1 degrees C due to grain-boundary diffusion alone, according to isotope exchange experiments on foraminifera tests. The oxygen isotopic compositions of fossil foraminifera tests constitute a continuous proxy record of deep-ocean and sea-surface temperatures spanning the last 120 million years. Here, by incubating foraminifera tests in O-18-enriched artificial seawater analogues, we demonstrate that the oxygen isotopic composition of optically translucent, i.e., glassy, fossil foraminifera calcite tests can be measurably altered at low temperatures through rapid oxygen grain-boundary diffusion without any visible ultrastructural changes. Oxygen grain boundary diffusion occurs sufficiently fast in foraminifera tests that, under normal upper oceanic sediment conditions, their grain boundaries will be in oxygen isotopic equilibrium with the surrounding pore fluids on a time scale of

SPRINGERNATURE2023