Revolutionary discovery: This is how complex eukaryotes emerged!

Revolutionary discovery: This is how complex eukaryotes emerged!

In a groundbreaking study, researchers from Mainz, Valencia, Madrid and Zurich have gained important insights into the formation of eukaryotes. How presse.uni-mainz.de reported, scientists focused on understanding the evolution of complex cells that form the basis of species such as fungi, plants and animals.

Early life forms were limited to prokaryotic cells that had genetic material floating around in the cytoplasm. In contrast, eukaryotes have a cell nucleus and numerous organelles that enable a complex cell structure. The formation of these complex cells is explained by the endosymbiont theory, which postulates that eukaryotes arose through a symbiosis between bacteria and archaea.

Evolutionary transitions and gene growth

A central aspect of the research is the lack of evolutionary intermediates between prokaryotes and eukaryotes. The results were published in the renowned scientific journal PNAS, with the researchers using quantitative methods to analyze the growth and evolution of genes.

They initially observed uniform growth of the protein-coding genes, followed by tensions that emerged as the genes continued to grow. It turns out that evolution integrated non-coding regions into the gene blueprint to support the growth of genes. Interestingly, the average protein length stagnated at around 500 amino acids, while the genes were still able to grow exponentially. A critical evolutionary transition is dated to 2.6 billion years ago.

These findings about the growth of genes are not only important for biology, but also have relevance for other scientific disciplines. The development of the eukaryotic cell laid the foundation for the development of multicellular organisms and sexuality.

The role of endosymbiosis

In addition to evolutionary development, it is important to consider the role of endosymbiosis. How bio.libretexts.org /20%3A_Phylogenies_and_the_History_of_Life/20.03%3A_Perspectives_on_the_Phylogenetic_Tree/20.3C%3A_Endosymbiotic_Theory_and_the_Evolution_of_Eukaryotes), horizontal gene transfer (HGT) can occur through genome fusion during endosymbiosis between different species. This process led to the creation of cells with genes from both organisms, which could explain the acquisition of mitochondria and chloroplasts.

However, there are still debates among scientists about the origin of the cell nucleus. Mitochondrial DNA comes from circular genomes of so-called “captured” bacteria and is only inherited maternally. Several hypotheses about the origin of eukaryotes and the cell nucleus compete, including the hypothesis that prokaryotes produced an additional membrane around bacterial chromosomes.

The question of whether the cell nucleus emerged first or only after fusion with bacteria remains open and requires further research. All hypotheses are testable and require further experimentation to determine which one is best supported by data.

Given the complementary approaches of evolutionary biologists, computational biologists and physicists, the study shows the potential of interdisciplinary collaboration in science and highlights the complexity of the evolution of life on Earth.