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A step towards synthetic cell synthesis

A U.S. research team led by Jack Szostak, the Nobel Price for medicine in 2009 and theacher of genetic at Massachussetts General Hospital(MGH), was able to obtain in laboratory a RNA replication through non-enzymatic way, inside fatty acid vescicles. It is a result that represent the major step towards the constructon of synthetic protocell, that is the first example of spontaneous cellular organizzation from the well known primordial soup.

A nucleic acid molecule within a vescicle, enclosed by a membrane of fatty acids: this may be the first cellular type and life organizzation. Understanding how life had started its existence has always been the fundamental question of biology. Untill now, what you can claim is that there was an appearance of a molecule (DNA) capable to recording genetic information and replication for all living organisms, enclosed insde a vescicle which separed this long molecule from the external environment.

That the first cell membrane was composed of fatty acids is an established fact by the same Szostak: a study published in "Science" in 2004, for example, made clear that the single presence of nucleic acid within a fatty acid vescicle gives benefit to the growth of membrane vescicle.

In another study in 2008, published on "Nature", scientists showed that fatty acids in water compose spontaneously vescicles above a certain concentration. These vescicles can bring to their internal place chemical compounds, including nucleic acids, without the help of proteins.

For this motive that Szostak with Katarzyna Adamala, researcher of Biology Department at Roma Tre University ( Rome, Italy), have studied the possibility that RNA replication was connected with different chemical compounds, such as Mg ions, athough they have a destabilizing effect on the membranes of fatty acids.

Researchers have been tested various chelating chemical agents, small molecules able to bind strongly metal ions, such as Mg ions, and prevent the destructive action. They have added in some vescicles of fatty acids pair of RNA strands, joined together in orfer to that strands longer acts as "copy" composed of only cytosine, and the second one, shorter, acts as primer for subsequent nucleotides addition in the sequence.

Finally, scientists added at the longer filament a sequence of guanine, the only nucleotide which can pair with the cytosine.

In the presence of Mg ions and citrate, the reaction has been documented: guanine has completed the chain, by extending the primer. Other two chelants have had opposite effects, preventing the filament growth.

 

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