Reverted Evolution.

Photo.Petr Tvrdik, Utah Courtesy.: Mouse top right, have facial paralysis (without gen Hoxb1). Right bottom, with rebuilt ancestral gen, without facial paralysis, blink eyes and put ears back in response to blow of air.

According to Rensch (Bernhard, 1980:60-100. Homo Sapiens, from animal to DemiGod. MappleHillsBooks.Ks,USA), once the species are differentiated (achieve specializations or determined complexities), the possibilities to come back to primitive forms or, to be directed in another sense are hopeless, in reason of to have exhausted all their evolutionary potential. This position is a biological dogma, as was it, the advanced (Crick,1958), that established that information is alone capable of flowing from DNA to RNA. Dogma placed in doubt in 1970, when it was discovered that some retrovirus, were capable of transmit information from RNA to DNA (Brown, T. A. Genetics. A molecular approach. Chapman and Hall, London. 1992:52). It was put again in doubt, mercy to recent experiments, sponsored by the Howard Hughes Medical Institut and carried out in the University of Utah (Petr Turdik and Mario Capecchi. Developmental Cell), in which code genetic combining regions (genetic regulatory sequences), of 2 modern genes originated in embryos of mice (gen: Hoxa1: controls development of mouse embryonic cerebral stem and gen: Hoxb1, orders formation of nervous cells, that control animal facial expression), has managed to be combined and reconstruct the functions of the ancient gene (Hox, 530 million years), that originated both of them and capable to carry out alone, the functions of both genes: Hoxa1-Hoxb1.

In the experiment the gene Hoxb1, of 2 mice are fuctionally disabled. The first one mouse is born with facial paralysis. To the second mouse is inserted code genetic portions of the gen Hoxa1, being born without paralisis facial -See pictures-. The reconstructed gen (Hoxa1-Hoxb1), equals functionally to the ancient gene, since it is capable of carrying out the functions of the 2 modern genes. These experiments are given information related to the form in which the nature promotes the evolution. Today, we know that each ancient gen, is divided into 2. Of the 4 resultants, 2 continue carrying out the initial work, in the meantime the 2 new, can be specialized, to change or to mutate. The mutated genes disappear or carry out protective functions of the health of the individual. It does: 530 -480 million years, the ancient gene (Hox), comprised 13 initial genes (it does 75 million –with the emergency of jaw fishes-, that become : 52). For some reason – natural rule out or, disuse- the present mammals (included the humans), alone have 39 Hox genes. With these experiments, the doors of new genetic therapies are opened. It is to suppose that the faulty gene of the Hemophilia A, should have a twin gene in some part of the body (liver, brain, etc). Identifying it, we could combine the code areas of the faulty hemophilic gen, with that of its modern twin gen, building the ancient gen that originated them and curing the sick patient. A short time before, David Haussler (Genome Resarch), of the University McGill of Canada, assembled 10 ancient genes (CFTR, locus), belonging to a small placental mammal that existed 75 million years ago jointly with dinosaurs. The novel thing of this experiment is that it was preceded and predicted with great accuracy mercy to simulations carried out with computers and comparative genomic (between humans and animal related species: hog, horse, mouse, orangutan, chimp, etc.).

Evolución revertida.

Según Rensch (Bernhard,1980:60-100. Homo Sapiens, de animal a semiDios. Alianza Editorial, Madrid), una vez que las especies se diferencian (logran especializaciones o determinadas complejidades), las posibilidades de regresionar a formas primitivas o, direccionarse en otro sentido son nulas, en razón de haber agotado todo su potencial evolutivo. Esta posición es un dogma biológico, como lo fué, el postulado (Crick,1958), que establecia que la información solo es capaz de fluir del DNA al RNA. Dogma puesto en duda en 1970, al descubrirse que algunos retrovirus, pueden trasmitir informacion del RNA al DNA (Brown, T.A. Genetics. A molecular approach. Chapman and Hall, London. 1992:52). Vuelto a poner en duda, merced a recientes experimentos, patrocinados por el Howard Hughes Medical Institut, realizados en la Universidad de Utah (Petr Turdik and Mario Capecchi. Developmental Cell, August, 2006), en los que combinando regiones codificadoras (secuencias regulatorias genéeticas), de 2 genes modernos procedentes de embriones de ratón (gen: Hoxa1 : controla desarrollo del tallo cerebral embrionario y gen: Hoxb1, ordena formación de celulas nerviosas, que controlan expresión facial animal), se ha logrado reconstruir las funciones del gen ancestral que los originó (Hox, 530 millones, capaz de realizar por si solo, las funciones de ambos genes : Hoxa1-Hoxb1).

En el experimento se inhabilita funcionalmente al gen Hoxb1, de 2 ratones. El primer ratón sin tratamiento, nace con paralisis facial. Al embrión del segundo ratón, se le inserta porciones codificadoras especificas del gen Hoxa1, naciendo sin paralisis facial -Ver fotos-. El gen reconstruido (Hoxa1-Hoxb1), equivale funcionalmente al gen ancestral, ya que es capaz de realizar las funciones de los 2 genes modernos. Estos experimentos estan proporciondo información relacionada con la forma en que la naturaleza promueve la evolucion. Hoy, sabemos que cada gen ancestral, se divide en 2. De los 4 resultantes, 2 continuan realizando el trabajo inicial, en tanto los 2 nuevos pueden especializarse, cambiar o mutar. Los genes mutados desaparecen o realizan funciones protectoras de la salud del individuo. Hace : 530 -480 millones de años, el gen ancestral (Hox), comprendia 13 genes iniciales (tornados hace 75 millones –con la emergencia de peces con mandibula-, en 52). Por alguna razon -descarte natural o, desuso- los mamiferos actuales (incluido los humanos), solo disponen de 39 genes Hox. Con estos experimentos, se abren las puertas de nuevas terapias génicas. Es de suponer que el gen defectuoso de la Hemofilia A, debe tener un gen gemelo en alguna parte del organismo (higado, cerebro,etc). Identificándolo, se podrian combinar las areas codificadoras del gen hemofilico defectuoso, con el de su gen gemelo moderno, recreando al gen ancestral que los originó y curando al paciente enfermo. Un poco antes, David Haussler (Genome Resarch), de la Universidad McGill de Canada, logró recontruir un conjunto de 10 genes ancestrales (CFTR, locus), pertenecientes a un pequeño mamifero placentario que existió hace 75 millones de años conjuntamente con los dinosaurios. Lo novedoso de este experimento es que fué precedido y predicho con gran exactitud merced a simulaciones realizadas con ordenadores y genomica comparativa (entre humanos y especies animales relacionadas :cerdo, caballo, raton, orangután, chimpancé, etc).