"Jurassic Park" : everybody remembers the film of Steven Spielberg. Scientists succeed in extracting dinosaurs 1 ADN by taking a sample in a prisoner mosquito of a block of amber of the blood globules of the big reptile whom it had pricked millions of years ago. The DNA REPAIRED AND SUPPLEMENTED is transplanted in an ovule not fertilised by crocodile and the dinosaurs come back to life in the XXth century!

 This invention, will say to you the geneticists, draws inspiration in the main lines of the principle of cloning (to see farther) but is completely unachievable, because l DNA is fragile, and, although locked up in the amber, it would have completely degraded in the course of time! 

On the other hand and there it is not any more the cinema! - they can manipulate genetically various organisms today, in various purposes: for example, it is possible to slip a gene of fish living in cold waters in strawberries to make them resistant to the low temperatures, or to transfer a gene of bacterium (cholera) in the alfalfa to produce a vaccine against the cholera

But what are techniques used to come to this?
The secret code of life
First, what 1 ADN? The DNA, or the acid d soxyribonucl ique, is a molecule with the particular faculty to retort in identity. What makes naturally the support of heredity. And where is the DNA? In each of our cells.

The molecule of DNA comes under the aspect of a long  necklace>> forming a double aircraft propeller. This " necklace  is composed of four bases ( " pearls>> of the necklace), called nucl otides. Their scheduling throughout the "necklace" of DNA constitutes the genetic code, which is peculiar to every individual.

According to organisms, the "necklace" is more or less long: for example, the unwound human DNA would measure about 1,8m, while the DNA of a bacterium would measure 1,3 mm.

Every group of "pearls" constitutes a gene. Every gene has as mission to fabricate or to transmit order to fabricate a protein necessary to the functioning of organism.

But it happens that bases inside one or several genes  are badly lined up  . An inversion in their order can procreate a hereditary illness.

In search of  genes has risk 
The discovery of deficient genes at the origin of hereditary monog niques diseases (owed for lack of the single gene) is already well moved forward thanks to the programme genome led in a thousand laboratories of the whole world: 1500 were identified at present on 6 000 hereditary monog niques listed diseases.  This knowledge of genes and of their mechanism of clean action is going to bring indisputable benefits in terms of predictive and preventive medicine and of therapeutics >, underlines the Pr Claudine Junien, geneticist in the hospital Necker of Paris. In practice, they accomplish genetic tests today searching  genes at risk  . The most knowing is the test of prenatal diagnosis at the pregnant woman being more than 38 years old and to those who have a  heavy heredity  . From cells of the foetus, this test discerns, besides chromosome aberrations portray trisomy 21, responsible for the mongolism - a lot of hereditary monog niques diseases.  In case of genetic anomaly drawing away in an ineluctable way a serious illness at the child>> it allows the abortion, leaving naturally to the parents any freedom of decision in the field.

The genetic tests practiced before the appearance of the signs of a serious illness are useful when it exists in a family of the antecedents of this illness. Some hereditary cancers (of the colon, the breast, for example), can so, thanks to early detections, benefit from a preventive surgery stopping evolution towards lethal cancers.

Soon  biological plants  ?
And if genes undamaged were used to treat on diseases? By transferring "healthy human genes  in animal organisms formed by the single cell and which increase by sexless reproduction, the researchers succeeded in creating biological plants of medicinal substances.

As for introducing genes undamaged into human organism to make them work faulty genes in loco, we are only at the very beginning of clinical trials on about fifteen hereditary diseases, of which the mucoviscidose. Results are for the moment disappointing, because they still do not manage to make sure that "refreshing" gene  fabricates the molecule code of which it keeps. But researches go on.

On the other hand, there is a border in these "repairs" : the "refreshing" genes  introduced into cells of the body will not stay in hereditary heritage and will not therefore be transmissible

Animal milk to fabricate medicaments?
Are we going to see the appearance of   animals plants  specialised in the production of medicaments? It is possible: cows, ewes or goats will be able to produce human proteins in their milk having accepted a human gene.  Less than a dozen years after the first trials, technology passes to the industrial ladder  , says the professor of medicine G rard Tobelen in its book  Biotechnologies: the right of knowledge  , appeared in June, 1998. <Three so produced proteins are mime in clinical development at the man (.) extracted from goat's milk, of brehis and from doe ( ) they treat respectively vascular embolisms, pulmonary I' emphysema and hepatic complications of the sick genetically showing a deficit in these proteins. 

Other experiments succeeded: transplant on cows, ewes, pigs, genes ordering the training of useful elements in the care of h mophiles and particular antibodies intended to destroy s lectivement the cancerous cells.

The first steps of animal cloning
We all heard about the first cloned ewe, Dolly Comment the British researchers could they get this ewe's certified copy without passing by natural procreation?  Principle is simple, explains the Pr Axel Kahn. To the left, you have ewe's ovule core of which was taken away. To the right, you take a cell of an ewe Finn Dorset which you want to clone (to copy out). This one contains in the core two games of chromosomes: an existent of his father and one of his mother. You put both cells in touch and, thanks to an electric shock, you operate on fusion between the big ovule emptied of its core and the small cell and the activation of embryonic development. You get, after establishment of the embryo in an ewe  mother holder  , Dolly with two same chromosomal games as with Finn Dorset and who resembles him therefore in every way. It is a reproduction in the identity which, in different from sexual reproduction, does not blend characters 

Cloning walks even better since it is made from a young organism in undamaged genes. The first experiments on mammals are currently studied from too close distance: some signs and premature deceases ask question.

After cloning of the animals, human cloning?
Fortunately, it is not for tomorrow. Because if the scientific community admits the interest of the cloning of some animals to produce in big quantities of the medicinal molecules difficult to get in another way, she rises up in most against the possible drift of this practice, as notably human cloning for reproductive aims.

Transg niques plants, food of future?

On the side of plants, several ways open in genetic engineering.
Since plants can decipher our genetic code, is it possible to use them to fabricate useful proteins to the man? It is principle of " molecular pharming " , already at the experimental stadium: they succeeded in making produce some haemoglobin and some albumin human in the tobacco, and vaccines against influenza and rage will be able to be fabricated by some rape, against hepatitis B by potatoes or tomatoes

They think to be also possible, thanks to the transfer of genes, to improve the nutritional quality of plants to get food  in added value>>, food less allergisants, or else capable of protecting us against some diseases (alicaments).

Finally, the way most known of genetic engineering aims at improving plants genetically so that they less need manure and insecticides. So, the corn transg nique has a gene which fabricates a toxin destroying the pyrale, parasite of the plant.

Currently, they count several dozens genetically modified vegetables cultivated in the world. Do this GMO introduce a danger for health? Some people think of it or fear it, and the authorities of some countries asked to postpone the industrialisation of their culture so that we have more detachment on consequences of their use. And it in spite of the affirmations of many scientists. The professor Berche, for example, argues:  GMO products under high surveillance are. As for the fears of acquiring resistance to antibiotics by absorbing them (because some genes of resistance fighter in antibiotics are used as  markers  in their manufacture), they are groundless, given that the ingested DNA is fast destroyed in the alimentary canal. Besides, mimes genes of resistance to antibiotics are already present in the intestine many people.

However, it is necessary to stress the fact that every GMO can pose a particular problem, which owes tre examined case by case.  According to this principle of precaution, all rapes and Transg niques beetroots (made resistant to weed killers) are currently forbidden to culture, marriage of their seeds with some grasses that can pose problem.

The workmanship of the living being, which is only beginning, gives therefore a source of unhoped potential applications, the men of which will be able to draw the best, if they can avoid the worst there.