création de la vie en laboratoire

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Lensman
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création de la vie en laboratoire

Message par Lensman » ven. mai 21, 2010 2:11 pm

J'apprends ça. Est-ce vraiment de la vie entièrement synthétique? ça me ferait plaisir, mais je suis méfiant...
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Sciences 21/05/2010 à 13h11 (site de Libération)

Des chercheurs ont créé une cellule vivante

Des chercheurs américains sont parvenus à créer une cellule bactérienne vivante dont le génome est synthétique, une avancée aux multiples applications potentielles devant permettre de mieux comprendre les mécanismes de la vie, selon leurs travaux publiés jeudi.

«Il s’agit de la création de la première cellule vivante synthétique au sens où celle-ci est entièrement dérivée d’un chromosome synthétique», explique Craig Venter, créateur de l’Institut du même nom et co-auteur du premier séquençage du génome humain dévoilé en 2000.

«Ce chromosome -- élément porteur de l’information génétique contenant un groupe de gènes de l’organisme, ndlr-- a été produit à partir de quatre flacons de substances chimiques et d’un synthétiseur, le tout ayant commencé avec des informations dans un ordinateur», poursuit-il, qualifiant ce succès «d’étape importante scientifiquement et philosophiquement».

Cette percée «change certainement ma vision de la définition de la vie et de son fonctionnement», ajoute ce chercheur dont les travaux paraissent dans la revue américaine Science du 21 mai.

«Cette approche est en effet un très puissant instrument pour tenter de concevoir ce que nous attendons de la biologie et nous pensons à cet égard à une gamme étendue d’applications», précise-t-il.

Craig Venter avait annoncé en 2008 être parvenu avec son équipe à fabriquer un génome bactérien 100% synthétique en collant des séquences d’ADN synthétisées bout à bout afin de reconstituer le génome complet de la bactérie Mycoplasma genitalium.

L’avancée annoncée jeudi découle de ces travaux antérieurs et ouvre effectivement la voie à des applications environnementales et énergétiques.

C’est ainsi que ces chercheurs vont tenter de concevoir des algues capables de capturer le dioxyde de carbone (CO2), principal gaz à effet de serre, et de produire de nouveaux hydrocarbures propres.

Ces scientifiques travaillent aussi sur des techniques capables d’accélérer la production de vaccins et de fabriquer de nouveaux ingrédients alimentaires et substances chimiques.

(Source AFP)
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Oncle Joe

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Message par Bull » ven. mai 21, 2010 4:58 pm

C'est amusant, je reçois en ce moment plusieurs mels me demandant ce que j'en pense.
Visiblement ce papier a "touché" le grand publique.

Oncle Joe, nous avions déjà eu cette discussion en Août dernier

(http://www.actusf.com/forum/viewtopic.p ... sc&start=0).

Et j'avais justement pris comme exemple Craig Venter et ses travaux.


Oui, un pas de plus a bien été franchi dans la création de la vie...

L'abstract du papier de cette semaine dans Science :
Published Online May 20, 2010 Science DOI: 10.1126/science.1190719


Creation of a Bacterial Cell Controlled by a Chemically Synthesized Genome

Daniel G. Gibson,1 John I. Glass,1 Carole Lartigue,1 Vladimir N. Noskov,1 Ray-Yuan Chuang,1 Mikkel A. Algire,1 Gwynedd A. Benders,2 Michael G. Montague,1 Li Ma,1 Monzia M. Moodie,1 Chuck Merryman,1 Sanjay Vashee,1 Radha Krishnakumar,1 Nacyra Assad-Garcia,1 Cynthia Andrews-Pfannkoch,1 Evgeniya A. Denisova,1 Lei Young,1 Zhi-Qing Qi,1 Thomas H. Segall-Shapiro,1 Christopher H. Calvey,1 Prashanth P. Parmar,1 Clyde A. Hutchison, III,2 Hamilton O. Smith,2 J. Craig Venter1,2,*

We report the design, synthesis, and assembly of the 1.08-Mbp Mycoplasma mycoides JCVI-syn1.0 genome starting from digitized genome sequence information and its transplantation into a Mycoplasma capricolum recipient cell to create new Mycoplasma mycoides cells that are controlled only by the synthetic chromosome. The only DNA in the cells is the designed synthetic DNA sequence, including "watermark" sequences and other designed gene deletions and polymorphisms, and mutations acquired during the building process. The new cells have expected phenotypic properties and are capable of continuous self-replication.

1 The J. Craig Venter Institute, 9704 Medical Center Drive, Rockville, MD 20850, USA.
2 The J. Craig Venter Institute, 10355 Science Center Drive, San Diego, CA 92121, USA.

* To whom correspondence should be addressed. E-mail: jcventer@jcvi.org

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Message par MF » ven. mai 21, 2010 5:13 pm

le Mycoplasma capricolum recipient réceptacle est-il naturel ou synthétique ?
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Message par Bull » ven. mai 21, 2010 5:25 pm

Naturel.

Toute l'histoire de cette "création de la vie en laboratoire" et les différentes étapes clefs qui l'ont emaillé ces dernières années ci-dessous.

C'est en anglais desolé. Pas le temps de le traduire.
Science 21 May 2010:
Vol. 328. no. 5981, pp. 958 - 959
DOI: 10.1126/science.328.5981.958

Synthetic Genome Brings New Life to Bacterium

Elizabeth Pennisi

For 15 years, J. Craig Venter has chased a dream: to build a genome from scratch and use it to make synthetic life. Now, he and his team at the J. Craig Venter Institute (JCVI) in Rockville, Maryland, and San Diego, California, say they have realized that dream. In this week's Science Express (www.sciencemag.org/cgi/content/abstract/science.1190719), they describe the stepwise creation of a bacterial chromosome and the successful transfer of it into a bacterium, where it replaced the native DNA. Powered by the synthetic genome, that microbial cell began replicating and making a new set of proteins.

This is "a defining moment in the history of biology and biotechnology," says Mark Bedau, a philosopher at Reed College in Portland, Oregon, and editor of the scientific journal Artificial Life. "It represents an important technical milestone in the new field of synthetic genomics," says yeast biologist Jef Boeke of Johns Hopkins University School of Medicine in Baltimore, Maryland.

The synthetic genome created by Venter's team is almost identical to that of a natural bacterium. It was achieved at great expense, an estimated $40 million, and effort, 20 people working for more than a decade. Despite this success, creating heavily customized genomes, such as ones that make fuels or pharmaceuticals, and getting them to "boot" up the same way in a cell is not yet a reality. "There are great challenges ahead before genetic engineers can mix, match, and fully design an organism's genome from scratch," notes Paul Keim, a molecular geneticist at Northern Arizona University in Flagstaff.

The "synthetic" bacteria unveiled this week have their origins in a project headed by Venter and JCVI colleagues Clyde Hutchison III and Hamilton Smith to determine the minimal instructions needed for microbial life and from there add genes that could turn a bacterium into a factory producing compounds useful for humankind. In 1995, a team led by the trio sequenced the 600,000-base chromosome of a bacterium called Mycoplasma genitalium, the smallest genome of a free-living organism. The microbe has about 500 genes, and researchers found they could delete 100 individual genes without ill effect (Science, 14 February 2003, p. 1006).

But confirming the minimal genome suggested by those experiments required synthesizing a full bacterial chromosome and getting it to work in a recipient cell, two steps that have taken years because the technology to make and manipulate whole chromosomes did not exist. In 2007, Venter, Smith, Hutchison, and colleagues finally demonstrated that they could transplant natural chromosomes from one microbial species to another (Science, 3 August 2007, p. 632). By 2008, they showed that they could make an artificial chromosome that matched M. genitalium's but also contained "watermark" DNA sequences that would enable them to tell the synthetic genome from the natural one (Science, 29 February 2008, p. 1215).


But combining those steps became bogged down, in part because M. genitalium grows so slowly that one experiment can take weeks to complete. The team decided to change microbes in midstream, sequencing the 1-million-base genome of the faster-growing M. mycoides and beginning to build a synthetic copy of its chromosome. Last year, they showed they could extract the M. mycoides natural chromosome, place it into yeast, modify the bacterial genome, and then transfer it to M. capricolum, a close microbial relative (Science, 21 August 2009, p. 928; 25 September 2009, p. 1693). The next step was to show that the synthetic copy of the bacterial DNA could be handled the same way.

The researchers started building their synthetic chromosome by going DNA shopping. They bought from a company more than 1000 1080-base sequences that covered the whole M. mycoides genome; to facilitate their assembly in the correct order, the ends of each sequence had 80 bases that overlapped with its neighbors. So that the assembled genome would be recognizable as synthetic, four of the ordered DNA sequences contained strings of bases that, in code, spell out an e-mail address, the names of many of the people involved in the project, and a few famous quotations.

Using yeast to assemble the synthetic DNA in stages, the researchers first stitched together 10,000-base sequences, then 100,000-base sequences, and finally the complete genome. However, when they initially put the synthetic genome into M. capricolum, nothing happened. Like computer programmers debugging faulty software, they systematically transplanted combinations of synthetic and natural DNA, finally homing in on a single-base mistake in the synthetic genome. The error delayed the project 3 months.

After months of unsuccessfully transplanting these various genome combinations, the team's fortune changed about a month ago when the biologists found a blue colony of bacteria had rapidly grown on a lab plate over the weekend. (Blue showed the cells were using the new genome). Project leader Daniel Gibson sent Venter a text message declaring success. "I took my video camera in and filmed [the plate]," says Venter.

They sequenced the DNA in this colony, confirming that the bacteria had the synthetic genome, and checked that the microbes were indeed making proteins characteristic of M. mycoides rather than M capricolum. The colony grew like a typical M. mycoides as well. "We clearly transformed one cell into another," says Venter.

"That's a pretty amazing accomplishment," says Anthony Forster, a molecular biologist at Vanderbilt University in Nashville, Tennessee. Still, he and others emphasize that this work didn't create a truly synthetic life form, because the genome was put into an existing cell.

At the moment, the techniques employed by Venter's team are too difficult to appeal to any potential bioterrorists, researchers stress. Nonetheless, "this experiment will certainly reconfigure the ethical imagination," says Paul Rabinow, an anthropologist at the University of California, Berkeley, who studies synthetic biology. "Over the long term, the approach will be used to synthesize increasingly novel designed genomes," says Kenneth Oye, a social scientist at the Massachusetts Institute of Technology in Cambridge. "Right now, we are shooting in the dark as to what the long-term benefits and long-term risks will be."

As ever more "artificial" life comes into reach, regulatory agencies will need to establish the proper regulations in a timely fashion, adds Oye. "The possibility of misuse unfortunately exists," says Eckard Wimmer of Stony Brook University in New York state, who led a team that in 2002 created the first synthetic virus (Science, 9 August 2002, p. 1016).

Venter says that JCVI has applied for several patents covering the work, assigning them to his company, Synthetic Genomics, which provided much of the funding for the project. A technology watchdog group, ETC Group in Ottawa, has argued that these actions could result in a monopoly on synthesized life (Science, 15 June 2007, p. 1557), but others are not worried. Given the current climate for granting and upholding patents of this type, says Oye, "it is unlikely that Synthetic Genomics will become the Microsoft of synthetic biology."

"One thing is sure," Boeke says. "Interesting creatures will be bubbling out of the Venter Institute's labs."

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Message par MF » ven. mai 21, 2010 5:31 pm

Bull a écrit :Naturel.

Toute l'histoire de cette "création de la vie en laboratoire" et les différentes étapes clefs qui l'ont emaillé ces dernières années ci-dessous.
Merci Bull.

Donc, si je comprends bien, on fabrique un ADN totalement synthétique et l'on remplace l'ADN d'un cellule vivante, qui continue à fonctionner comme si de rien n'était en suivant les instructions de l'ADN synthétique.

Il ne reste donc plus qu'à passer à la phase suivante : un test en grandeur réelle sur Paris Hilton !
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Message par Lensman » ven. mai 21, 2010 6:48 pm

C'est encore un peu hybride, mais ça avance!
Oncle Joe

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