Energy is essential, even in the realm of evolutionary inventions: the aliens would also need the mitochondria.
Researchers in Germany and the United Kingdom presented a completely new theory for the evolution of complex life, suggesting that it depends on the mitochondria, the small power plants that are found in cells known as eukaryotes, which include all forms of complex life on Our planet, like animals, plants, fungi and algae. The research, funded in part by the EU, was presented recently in the journal Nature.
Scientists had long believed that the evolution of the core was the key to complex life. However, Dr. Nick Lane at University College London (UCL) in the United Kingdom and Dr. William Martin of the University of Dusseldorf in Germany, believe that mitochondria, the powerhouses of their function in the cell, who played a key role in the development of complex innovations such as the nucleus.
“The basic principles are universal,” said Dr. Lane Department of Genetics, evolution and environment of the UCL. “Energy is essential, even in the realm of evolutionary inventions. Even the aliens would need the mitochondria.”
According to Dr. Lane, their discovery overturns the traditional view that the transition to complex eukaryotic cells require just the right kind of changes, “pointing out that evolution from simple prokaryotes, like bacteria,” in reality would require a kind of industrial revolution in terms of energy production. ”
Dr. Lane said that at the level of our cells, humans have more in common with fungi, magnolias and carnations with bacteria, complex cells, since we share with specialized compartments that include an information center, the nucleus, and mitochondria. All of these eukaryotes share a common ancestor that appeared only once in four billion years of evolution.
The researchers demonstrated how eukaryotes accumulate additional genes and proteins, while the bacteria do not bother to do so. Focusing on energy available for each gene, the researchers showed that a typical eukaryotic cell can support a number of genes compared to 200,000 times more bacteria.
“This provides the eukaryote genetic raw materials that allow them to accumulate new genes, large gene families and control systems on a scale completely outside the scope of the bacteria,” said Dr. Lane. “This is the basis of complexity, even if it is not always used.” He also stressed that “bacteria can be found at the bottom of a deep chasm in the energy landscape, and have never found a way out,” adding that “most eukaryotes the mitochondria provide the energy for each gene in four orders of magnitude or five times higher, and this has put them in a position to dig a tunnel directly through the walls of the abyss. ”
The researchers also found that bacteria are not able to be divided into compartments to capture the benefits arising from the possession of mitochondria. The answer lies, in their view, small mitochondrial genome, adding that these genes are necessary for cellular respiration, and that without them dying eukaryotic cells. If the cells get bigger and stronger, they need multiple copies of mitochondrial genes to stay alive.
The bacteria are faced with exactly the same problem. They can handle the making thousands of copies of the whole genome, but all of that DNA (deoxyribonucleic acid) has a high cost of energy that paralyzes even the giant bacteria and prevents their transformation into more complex eukaryotes.
“The only way out is whether a cell somehow breaks into another, a endosymbiosis,” said Dr. Lane. However, while the cells within other cells are common among eukaryotes, which often engulf other cells, they are extremely rare in the more stringent bacteria. And this – the researchers conclude – may well explain why complex life evolved only once during the entire history of Earth.
