Phaeocystis globosa is an alga forming harmful blooms in the coastal waters of the North Sea. The decay of algal biomass at the end of the bloom leads to massive release of organic matter, which in turn stimulates the growth of a variety of heterotrophic gamma- and alpha-proteobacteria.
Formation of filamentous star-like structures here visualized with atomic force microscopy.
Max Planck Institute for Marine Microbiology
Formation of filamentous star-like structures here visualized with nanoSIMS
Max Planck Institute for Marine Microbiology
‘An important source of mortality for these algae are lytic P. globosa viruses. We therefore investigated how algal viral infection and subsequent lysis affects the community structure of the associated bacteria,’ explains Dr. Abdul R. Sheik, the lead author of this study.
In control experiments they showed that the bacterial composition of infected algal cultures differed from non-infected cultures after 5 hours. In order to understand the underlying mechanism Dr. Sheik and colleagues monitored the uptake of the released organic material by the bacterioplankton using isotopically-labeled algal biomass (with isotopes of nitrogen and carbon).
Assimilation of the substrate was quantified in single bacterial cells using imaging secondary ion mass spectrometry (nanoSIMS) with a sub-micrometer spatial resolution. ‘Surprisingly, we saw colonization of algal cells and uptake of labeled carbon and nitrogen by Alteromonas cells long before the algal cells lysed’, explains Abdul Sheik. ‘This suggests that infected but still intact algae can already shape the microbial community composition by excretion or leakage of organic matter.’
The bacterial turnover of algal products was so rapid that ca. 40% of the particulate organic carbon was re-mineralized to CO2 within one week after infection, leaving behind refractive material in the form of cellular star-like structures (see Figure).
These results reveal a new pathway in the transfer of algal biomass to the bacterioplankton and, in a larger picture, new mechanism of retaining carbon in the euphotic zone.
Dr. Manfred Schloesser | Max-Planck-Institut
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22.09.2017 | DFG-Forschungszentrum für Regenerative Therapien TU Dresden
The pyrenoid is a carbon-fixing liquid droplet
22.09.2017 | Max-Planck-Institut für Biochemie
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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