Researchers at the University of Liège (ULiège) have identified the ultrastructure of a 1.75 billion-year-old fossil cell.
These structures, called thylakoid membranes, are the oldest ever discovered. They push back the thylakoid fossil record by 1.2 billion years and provide new information about the evolution of cyanobacteria, which played a key role in early Earth’s oxygen accumulation. This significant discovery was published in the journal Nature.
Catherine Dumoulin, Yannick Lara, Alexandre Lambion, and Emmanuel Javeau of the Early Life Signs and Evolution Laboratory of the Astrobiology Research Unit in Uliège have discovered Nabyfusa magensis (N. We investigated a mysterious microfossil called A. majensis. The same goes for his billion-year-old geological formations in the Democratic Republic of Congo and Arctic Canada. Ultrastructural analysis of fossil cells from two geological formations (Australia and Canada) revealed the presence of an internal membrane with an arrangement, microstructure, and dimensions that clearly interpret it as a thylakoid membrane in which oxygenic photosynthesis occurs. These observations confirmed that N majensis is a fossil cyanobacterium.
This discovery reveals the role of cyanobacteria with thylakoid membranes in early Earth oxygenation. They played an important role in the early evolution of life and were active during the Great Oxygenation Event (GOE) about 2.4 billion years ago. However, the date of the origin of oxygenic photosynthesis and the type of cyanobacteria involved (protocyanobacteria? With or without thylakoids?) are still debated, and the ULiège researchers’ findings may help clarify these questions. provides a new approach to
Image of a microfossil specimen of Navifusa majensis. (Demoulin et al., Nature, 2024) [L] One of the microfossils with a stack of thylakoids highlighted with yellow bars [R] Enlarged view of the edge of the cell.
“The oldest known fossil thylakoids date back about 550 million years, so what we’ve identified extends the fossil record by 1.2 billion years,” says paleontologist Dr. explains Professor Emmanuel Javeau, astrobiologist and director of Uriege’s Early Life Signs and Evolution Laboratory.
“The discovery of conserved thylakoids in N. magensis provides direct evidence that the minimum age of the divergence of cyanobacteria with and without thylakoids is approximately 1.75 billion years.”
But the ULiège team’s discovery, which uncovered thylakoids in even older cyanobacteria fossils, suggests that the appearance of thylakoids may have played a major role in the large-scale oxygenation of the early Earth some 2.4 billion years ago. This increases the possibility of testing the hypothesis. This approach also allows investigating the role of dioxygen in the evolution of complex life on Earth (eukaryotes), including the origin and early diversification of algae hosted by cyanobacteria-derived chloroplasts. Masu.
“Subtle life is beautiful and the most diverse life form on Earth since the beginning of life. Using new approaches to study its fossil record, we are discovering how life has evolved over at least 3.5 billion years. Part of this research will also tell us how to look for signs of extraterrestrial life!” concludes Emmanuel Javeau.
Image of a microfossil specimen of Navifusa majensis. (Demoulin et al., Nature, 2024)