by Staff Writers
Zurich, Switzerland (SPX) Jan 22, 2013
Cyanobacteria belong to the Earth's oldest organisms. They are still present today in oceans and waters and even in hot springs. By producing oxygen and evolving into multicellular forms, they played a key role in the emergence of organisms that breathe oxygen. This has, now, been demonstrated by a team of scientists under the supervision and instruction of evolutionary biologists from the University of Zurich.
According to their studies, cyanobacteria developed multicellularity around one billion years earlier than eukaryotes - cells with one true nucleus. At almost the same time as multicellular cyanobacteria appeared, a process of oxygenation began in the oceans and in the Earth's atmosphere.
Multicellularity as early as 2.3 billion years ago
"Multicellularity developed relatively early in the history of cyanobacteria, more than 2.3 billion years ago", Schirrmeister explains in her doctoral thesis, written at the University of Zurich.
Link between multicellularity and the Great Oxidation Event
Based on their data, Schirrmeister and her doctoral supervisor Homayoun Bagheri believe that there is a link between the emergence of multicellularity and the event.
According to Bagheri, multicellular life forms often have a more efficient metabolism than unicellular forms. The researchers are thus proposing the theory that the newly developed multicellularity of the cyanobacteria played a role in triggering the Great Oxidation Event.
Cyanobacteria occupied free niches
The researchers have determined the existence of many new types of multicellular cyanobacteria subsequent to the fundamental climatic event, and are deducing that these occupied the newly developed habitats. "Morphological changes in microorganisms such as bacteria were able to impact the environment fundamentally and to an extent scarcely imaginable", concludes Schirrmeister.
Great Oxidation Event
Previously, in the Earth's early atmosphere, there were only traces of free oxygen. All life was based exclusively on anaerobic processes - chemical reactions that did not require oxygen. With the emergence of cyanobacteria that oxidized water with the help of light and produced oxygen as a by-product, the conditions for life on Earth gradually began to transform.
Bettina E. Schirrmeister, Jurriaan M. de Vos, Alexandre Antonelli, Homayoun C. Bagheri. Evolution of multicellularity coincided with increased diversification of cyanobacteria and the Great Oxidation Event. PNAS Early Edition. January 14, 2013. doi: 10:1072/pnas.1209927110/-/DCSupplemental
University of Zurich
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