Certain bacteria can build such complex membrane structures that, in terms of complexity and dynamics, look like eukaryotes, i.e., organisms with a distinct membrane-bound nucleus. Scientists from Heidelberg University and the European Molecular Biology Laboratory (EMBL) made this discovery employing new methods in electron microscopy.
The research team succeeded in building a three-dimensional model of the Gemmata obscuriglobus bacterium, including the structure of its membrane system. Their studies proved, however, that the G. obscuriglobus does not have a “true” nucleus. Despite this outlier characteristic, it remains classified as a bacterium and thus a so-called prokaryote. The results of their research were published in “PloS Biology”.
“Since the beginning of microscopy, cells of living organisms have been classified into one of two categories,” explains Dr. Damien Devos, a researcher at the Centre for Organismal Studies (COS) at Heidelberg University. Eukaryotes “pack” their genetic material, their DNA, in an area enclosed in a membrane, the nucleus. Prokaryotes, however, which also include bacteria, do not have that type of cell nucleus. Several years ago, analyses using new techniques of two-dimensional imaging had suggested that the genetic material of G. obscuriglobus was surrounded by a double membrane – this and other unique characteristics of membrane structure called into question the differentiation between prokaryotes and eukaryotes.
“The possibility that a bacterium could have a structure similar to a cell nucleus threatened to unhinge one of the central assumptions of biology on which countless other analyses and interpretations were based,” explains Damien Devos. To study the unique features of the membrane structure in the G. obscuriglobus more closely, the Heidelberg researchers divided the bacterium into thin slices and examined them using an electron microscope. The slices were used to detect the membranes, track their course throughout the entire bacterium and reconstruct their organisation on the computer. This created a virtual model of G. obscuriglobus, which enabled the researchers to visualise the membrane organisation in three-dimensional space and analyse how the membranes were structured within the cell.
The studies demonstrated that the membranes within the G. obscuriglobus are only one part of the interior membrane that is present in all bacteria and that surrounds the cytoplasm. “G. obscuriglobus also evidenced additional characteristics that are found in other bacteria,” explains Damien Devos. According to the researcher, these results disprove the assumption of the existence of a bacterial cell nucleus. “The cell structure and the membranes of the Gemmata obscuriglobus are simply more complex than in ‘classic’ bacteria. Therefore, G. obscuriglobus does not constitute a new, separate group of organisms, and it cannot be classified a eukaryote,” says Dr. Devos, who collaborated with Rachel Santarella-Mellwig of the European Molecular Biology Laboratory.Film material on the Internet: http://www.bork.embl.de/~devos/project/apache/htdocs/plancto/g3d/
Other information on the Internet: http://www.cos.uni-heidelberg.de/index.php/j.wittbrodt/d.devosOriginal publication:
Marietta Fuhrmann-Koch | idw
World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
17.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering