Oldest known evidence of photosynthetic structures identified in a collection of mysterious cylindrical microfossils Nabyfusa magensis It was discovered in the 1.75 billion year old McDermott Formation in Australia.
Nabyfusa magensis Microfossil: (a) Nabyfusa magensis From the McDermott Formation of the Tawala Supergroup, northern Australia. (b) Nabyfusa magensis From the Grassy Bay Formation of the Shaler Supergroup in the Canadian Arctic. (c) Nabyfusa magensis From the Mbujimai supergroup BIIc6 formation in the Democratic Republic of the Congo. Scale bar – 50 μm. Image credit: Demoulin other., doi: 10.1038/s41586-023-06896-7.
Oxygenic photosynthesis, in which sunlight catalyzes the conversion of water and carbon dioxide to glucose and oxygen, is unique to cyanobacteria and related organelles within eukaryotes.
Cyanobacteria played an important role in the evolution of early life and were active before the B.C. big oxidation event Approximately 2.4 billion years ago, the timing of the origin of oxygenic photosynthesis is debated due to limited evidence.
“Today, oxygenic photosynthesis is unique to cyanobacteria and their plastid relatives within eukaryotes,” said the paleontologist at the University of Liege. Catherine Dumoulin And her colleagues.
“Although its origins before the Great Oxidation Event are still debated, the accumulation of oxygen profoundly altered Earth's redox chemistry and the evolution of the biosphere, which contains complex life.”
“Understanding the diversification of cyanobacteria is therefore critical to understanding the coevolution of our planet and life, but their early fossil record remains equivocal.”
In their research, Demoulin and his co-authors discovered fossilized photosynthetic structures. Nabyfusa magensis Microfossil.
The microstructure is thylakoid. A membrane-bound structure found inside the chloroplasts of plants and some modern cyanobacteria.
Researchers identified them from fossils taken from three different locations, the oldest of which is from Australia's McDermott Formation and dates to 1.75 billion years ago (Paleoproterozoic era).
Nabyfusa magensis It is thought to be a cyanobacterium. The discovery of thylakoids in specimens from this period suggests that photosynthesis may have evolved at some point 1.75 billion years ago.
However, the mystery of whether photosynthesis evolved before or after the Great Oxidation Event remains unsolved.
Similar ultrastructural analyzes of older microfossils could help answer this question and determine whether the evolution of thylakoids contributed to elevated oxygen levels during the Great Oxidation Event.
“This discovery extends the thylakoid fossil record by at least 1.2 billion years and establishes a minimum age for the divergence of thylakoid cyanobacteria to be about 1.75 billion years ago,” the authors said. .
“This allows for the unambiguous identification of early oxygenic photosynthetic substances and new redox substances for investigating early Earth ecosystems, and for deciphering the paleontology and early evolution of fossil cells. This highlights the importance of examining the ultrastructure of cells.”
team's paper Published in today's magazine Nature.
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CF Dumoulin other. The oldest known fossil cells, thylakoids, provide direct evidence of oxygenic photosynthesis. Nature, published online on January 3, 2024. doi: 10.1038/s41586-023-06896-7
Source: www.sci.news
