Alain Blanchard - Lundi 15 mars à 12h Title: From the question "what is life?" to the building of minimal cells. Abstract: For many centuries, the question about the meaning and nature of life has been central in philosophy and science. We have now gathered, through experimental approaches, a large body of knowledge about the organization of living organisms at different levels, but the question “what is life?” remains the object of debates. In fact, this question is in the spotlight for at least three reasons. The first one comes from the need to recognize life in extra-terrestrial systems, the second one is related to the understanding of the origin of life itself and the third one is linked to the development of cellular chassis using synthetic biology. Indeed, one of the goals of synthetic biology is to build novel living entities that would fulfill some of our needs. One of the pursued approaches aims at creating cellular chassis that would be close to the concept of a minimal cell. To reach that goal, one first needs to define the minimal information (i.e. essential genes) that is necessary and sufficient to support life, at least in the laboratory. The next step is to find a method to produce a cellular system that would use this set of essential genes as its genome. The type of resulting organism does not exist in Nature and is not the product of Evolution. This brings us back to the definition of a living organism because these entities are obviously not autonomous. I will briefly present some of the work that we are doing with mycoplasmas that are considered as models of natural and minimal cells and I will discuss the implications of this work in the context of the development of synthetic biology. Références spécialisées : – Szostak JW, Bartel DP, Luisi PL. Synthesizing life. Nature. 2001 Jan 18;409(6818):387-90. – Danchin A. Scaling up synthetic biology: Do not forget the chassis. FEBS Lett. 2012 Jul 16;586(15):2129-37. – Grosjean H, Breton M, Sirand-Pugnet P, Tardy F, Thiaucourt F, Citti C, Barré A, Yoshizawa S, Fourmy D, de Crécy-Lagard V, Blanchard A. Predicting the minimal translation apparatus: lessons from the reductive evolution of mollicutes. PLoS Genet. 2014 May 8;10(5):e1004363. – Gibson DG, Glass JI, Lartigue C, Noskov VN, Chuang RY, Algire MA, Benders GA, Montague MG, Ma L, Moodie MM, Merryman C, Vashee S, Krishnakumar R, Assad-Garcia N, Andrews-Pfannkoch C, Denisova EA, Young L, Qi ZQ, Segall-Shapiro TH, Calvey CH, Parmar PP, Hutchison CA 3rd, Smith HO, Venter JC. Creation of a bacterial cell controlled by a chemically synthesized genome. Science. 2010 Jul 2;329(5987):52-6. Références grand public : – Une vidéo de François Jacob en 2000 : http://www.canal-u.tv/video/universite_de_tous_les_savoirs/qu_est_ce_que_la_vie.880 – Une vidéo de Craig Venter sur « What is life ? » en 2012 enregistrée au Trinity College of Dublin : https://www.youtube.com/watch?v=qi2MhsUSu0U - Une vidéo TED : Martin Hanczyc: The line between life and not-life :https://www.ted.com/talks/martin_hanczyc_the_line_between_life_and_not_life – What Is Life?. (2015, December 24). In Wikipedia, The Free Encyclopedia. Retrieved 16:02, January 14, 2016, from https://en.wikipedia.org/w/index.php?title=What_Is_Life%3F&oldid=696596560 – Dossier spécial La Recherche :http://www.larecherche.fr/savoirs/dossier-special/2-est-ce-vie-01-10-2005-70772