Have rocky microfailles hosted the first “living cells” without membrane?

On Earth. In addition, if it is a characteristic shared by all living beings, it is that they are made of cells. Meanwhile, These elementary bricks of life house a complex machinery that produces the molecules necessary for their operation. Moreover, A membrane encapsulates all the content of a cell. Therefore, but it remains permeable in order to guarantee the passage of certain compounds, to bring nutrients or evacuate waste, for example. Moreover, These exchanges with the external environment are essential for the life of a cell. For example, but its porosity is only possible through certain proteins, which are produced by cell machinery. However, These proteins are part of the membrane and play the role of doors. Consequently, This universal structure in living beings. however, raises a question of size: if a cell cannot survive without membrane protein, but that these are have rocky microfailles hosted first produced by cell machinery, how did the first cells appear well? In the search for the origins of life. a certain number of tracks are studied, considering protocellules with or without membrane. Dieter Braun. professor at the University of Munich, and his colleagues offer a new approach: in close cavities subject to high temperature gradients, complex molecules are grouped spontaneously until triggering the transcription of DNA.

The team highlighted this laboratory mechanism in a vertical cavity of 170 micrometers in diameter filled with water. and maintained at constant temperature. This space, which resembles a microscopic well, is pierced with an input and an output in its upper part. There circulates a flow of water containing all the molecules of the cellular machinery of the bacteria They exhibited chill. a DNA sequence coding a fluorescent protein.

As it stands, have rocky microfailles hosted first nothing happens, the different molecules are too scattered to interact with each other. But when the researchers impose a temperature difference between the side walls of the cavity. 40 ° C on one side and 27 ° C on the other, two mechanisms are put in place. On the one hand. molecules derive towards the cold side by a thermodiffusion effect and, on the other hand, the temperature difference triggers a convection phenomenon. The hot water goes back to the top. cold water flows towards the bottom, all forming a loop over the entire height of the well.

Under the effect of these two processes. a light zone forms at the bottom of the cavity. Cellular machinery of the bacteria has gathered there. started the transcription of the gene and formed fluorescent proteins, without the need for membrane. Furthermore. the have rocky microfailles hosted first researchers observed exchanges of this “thermally assembled protocellule” with the external environment, suggesting the possibility of providing nutrients and eliminating waste.

Cavities of this type. for example are found in volcanic areas or in the cracks of black smokers, these chimneys of the ocean funds where the temperature gradients are precisely very important. Smokers were proposed as an environment conducive to the emergence of life in the 1980s. and the idea has remained since one of the privileged tracks.

If the assembly of this protocellule does not describe the formation of a living being as such. compatibility with the natural environment suggests that this physico-chemical mechanism may have played a role in the formation of the first cells. But “Even if we found a sufficient mechanism to reproduce complete cells in a natural environment. which would already be great, we will never really know if life is, indeed, appeared in have rocky microfailles hosted first this way”, Temperates Thomas Matreux, researcher at ESPCI Paris and co -author of the study.